start-ver=1.4 cd-journal=joma no-vol=74 cd-vols= no-issue= article-no= start-page=6009610 end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2025 dt-pub=2025 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Small Distance Increment Method for Measuring Complex Permittivity With mmWave Radar en-subtitle= kn-subtitle= en-abstract= kn-abstract=Measuring the complex permittivity of material is essential in many scenarios, such as quality checks in material manufacturing. Generally, measurement methods for characterizing the material are based on the use of a vector network analyzer (VNA), which is large and not easy for on-site measurement, especially in high-frequency range such as millimeter wave (mmWave). In addition, some measurement methods require the destruction of samples, which is not suitable for nondestructive inspection. In this work, a small distance increment (SDI) method is proposed to nondestructively measure the complex permittivity of a material. In SDI, the transmitter and receiver are formed as a monostatic radar, which is facing toward the material under test (MUT). During the measurement, the distance between the radar and the MUT changes with small increments, and the signals are recorded at each position. A mathematical model is formulated to depict the relationship among the complex permittivity, distance increment, and measured signals. By fitting the model, the complex permittivity of MUT is estimated. To implement and evaluate the proposed SDI method, a commercial off-the-shelf (COTS) mmWave radar is utilized, and the measurement system is developed. Then, the evaluation was carried out on the acrylic plate. With the proposed method, the estimated complex permittivity of the acrylic plate shows good agreement with the literature values, demonstrating the efficacy of the SDI method for characterizing the complex permittivity of the material. en-copyright= kn-copyright= en-aut-name=SongHang en-aut-sei=Song en-aut-mei=Hang kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=KimHyun Joon en-aut-sei=Kim en-aut-mei=Hyun Joon kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=WanMingxia en-aut-sei=Wan en-aut-mei=Mingxia kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=WeiBo en-aut-sei=Wei en-aut-mei=Bo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=KikkawaTakamaro en-aut-sei=Kikkawa en-aut-mei=Takamaro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=TakadaJun-Ichi en-aut-sei=Takada en-aut-mei=Jun-Ichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= affil-num=1 en-affil=Research Institute for Semiconductor Engineering, Hiroshima University kn-affil= affil-num=2 en-affil=Department of Transdisciplinary Science and Engineering, Institute of Science Tokyo kn-affil= affil-num=3 en-affil=Department of Transdisciplinary Science and Engineering, Institute of Science Tokyo kn-affil= affil-num=4 en-affil=Faculty of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=5 en-affil=Research Institute for Semiconductor Engineering, Hiroshima University kn-affil= affil-num=6 en-affil=Department of Transdisciplinary Science and Engineering, Institute of Science Tokyo kn-affil= en-keyword=Complex permittivity measurement kn-keyword=Complex permittivity measurement en-keyword=material characterization kn-keyword=material characterization en-keyword=millimeter wave (mmWave) radar kn-keyword=millimeter wave (mmWave) radar en-keyword=nondestructive inspection kn-keyword=nondestructive inspection en-keyword=small distance increment (SDI) method kn-keyword=small distance increment (SDI) method END start-ver=1.4 cd-journal=joma no-vol=13 cd-vols= no-issue= article-no= start-page= end-page= dt-received= dt-revised= dt-accepted= dt-pub-year=2025 dt-pub=2025 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Adaptive Topological Mapping With Free Area-Based Node Deletion for Autonomous Mobile Robots en-subtitle= kn-subtitle= en-abstract= kn-abstract=This paper proposes an adaptive topological map building method, called Adaptive Resonance Theory-based Topological Clustering with Different Topologies (ATC-DT), for autonomous mobile robots using 3D point cloud data. ATC-DT framework integrates a novel node deletion mechanism that detects layout changes through free area detection. This allows the robot to update topological maps dynamically, removing outdated nodes caused by environmental changes. Experiments in real environments validate the ability of the method to perform global path planning, free area estimation, and adaptive navigation. The approach significantly improves navigation performance by improving map relevance and reducing redundancy of paths. en-copyright= kn-copyright= en-aut-name=OzakiHaruka en-aut-sei=Ozaki en-aut-mei=Haruka kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=TodaYuichiro en-aut-sei=Toda en-aut-mei=Yuichiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=MasuyamaNaoki en-aut-sei=Masuyama en-aut-mei=Naoki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=FujiKai en-aut-sei=Fuji en-aut-mei=Kai kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=MatsunoTakayuki en-aut-sei=Matsuno en-aut-mei=Takayuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= affil-num=1 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Informatics, Osaka Metropolitan University kn-affil= affil-num=4 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=5 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= en-keyword=Topological map building kn-keyword=Topological map building en-keyword=navigation system kn-keyword=navigation system en-keyword=autonomous mobile robot kn-keyword=autonomous mobile robot END start-ver=1.4 cd-journal=joma no-vol=13 cd-vols= no-issue= article-no= start-page=185111 end-page=185124 dt-received= dt-revised= dt-accepted= dt-pub-year=2025 dt-pub=2025 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Enhancing Protection Against Code Reuse Attacks on IoT Devices by Randomizing Function Addresses en-subtitle= kn-subtitle= en-abstract= kn-abstract=Most Internet of Things (IoT) devices currently in use are vulnerable to code reuse attacks because manufacturers typically deploy the same firmware across all devices. This uniformity enables attackers to craft a single exploit that can compromise multiple devices. To mitigate this risk, we propose a firmware diversification approach that creates multiple executable files with varying software compositions. Our approach introduces two complementary techniques: Function Address Reordering (FAR), which randomizes the order of functions within object files during compilation, and Object Address Reordering (OAR), which permutes the linking order of object files in the final executable. These techniques collectively diversify firmware instances without altering runtime behavior, making executing code reuse attacks significantly more difficult. By deploying firmware with diverse executable files, it is possible to enhance security without altering device behavior. We evaluate the effectiveness and limitations of the proposed methods when integrated into actual IoT firmware, assessing their resilience to code reuse attacks, impact on runtime behavior, and compilation overhead. Experimental results demonstrate that FAR and OAR significantly reduce the success rate of return-oriented programming attacks while incurring minimal performance overhead. This study offers a scalable, hardware-independent defense against code reuse attacks that increases resilience without a significant performance overhead, rendering it practical for widespread adoption in various IoT applications. en-copyright= kn-copyright= en-aut-name=SajiKazuma en-aut-sei=Saji en-aut-mei=Kazuma kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=YamauchiToshihiro en-aut-sei=Yamauchi en-aut-mei=Toshihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=KobayashiSatoru en-aut-sei=Kobayashi en-aut-mei=Satoru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=TaniguchiHideo en-aut-sei=Taniguchi en-aut-mei=Hideo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Faculty of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Faculty of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= en-keyword=Code reuse attack kn-keyword=Code reuse attack en-keyword=IoT firmware kn-keyword=IoT firmware en-keyword=software diversity kn-keyword=software diversity en-keyword=function reordering kn-keyword=function reordering en-keyword=LLVM kn-keyword=LLVM END start-ver=1.4 cd-journal=joma no-vol=22 cd-vols= no-issue=5 article-no= start-page=3933 end-page=3946 dt-received= dt-revised= dt-accepted= dt-pub-year=2025 dt-pub=202510 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Topology-Driven Configuration of Emulation Networks With Deterministic Templating en-subtitle= kn-subtitle= en-abstract= kn-abstract=Network emulation is an important component of a digital twin for verifying network behavior without impacting on the service systems. Although we need to repeatedly change network topologies and configuration settings as a part of trial and error for verification, it is not easy to reflect the change without failures because the change affects multiple devices, even if it is as simple as adding a device. We present topology-driven configuration, an idea to separate network topology and generalized configuration to make it easy to change them. Based on this idea, we aim to realize a scalable, simple, and effective configuration platform for emulation networks. We design a configuration generation method using simple and deterministic config templates with a new network parameter data model, and implement it as dot2net. We evaluate three perspectives, scalability, simplicity, and efficacy, of the proposed method using dot2net through measurement and user experiments on existing test network scenarios. en-copyright= kn-copyright= en-aut-name=KobayashiSatoru en-aut-sei=Kobayashi en-aut-mei=Satoru kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=ShiibaRyusei en-aut-sei=Shiiba en-aut-mei=Ryusei kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=MiwaShinsuke en-aut-sei=Miwa en-aut-mei=Shinsuke kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=MiyachiToshiyuki en-aut-sei=Miyachi en-aut-mei=Toshiyuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=FukudaKensuke en-aut-sei=Fukuda en-aut-mei=Kensuke kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= affil-num=1 en-affil=Faculty of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Department of Informatics, School of Multidisciplinary Sciences, The Graduate University of Advanced Studies, Sokendai kn-affil= affil-num=3 en-affil=StarBED Technology Center, Testbed Research, Development and Operations Laboratory, National Institute of Information and Communications Technology kn-affil= affil-num=4 en-affil=Strategic Planning Department, Strategic Planning Office, National Institute of Information and Communications Technology kn-affil= affil-num=5 en-affil=Department of Informatics, School of Multidisciplinary Sciences, The Graduate University of Advanced Studies, Sokendai kn-affil= en-keyword=Configuration management kn-keyword=Configuration management en-keyword=template kn-keyword=template en-keyword=emulation network kn-keyword=emulation network en-keyword=topology graph kn-keyword=topology graph END start-ver=1.4 cd-journal=joma no-vol=61 cd-vols= no-issue=5 article-no= start-page=6848 end-page=6860 dt-received= dt-revised= dt-accepted= dt-pub-year=2025 dt-pub=20250401 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Impact of SMC Property on Axial-Flux Permanent Magnet Machine in Traction Applications en-subtitle= kn-subtitle= en-abstract= kn-abstract=This paper investigates the impact of soft magnetic composite (SMC) properties on an axial flux permanent magnet machine (AFPM) employing ferrite permanent magnet (PM) in traction applications. In general, the efficiency of an AFPM increases as the iron loss of the SMC decreases. However, the torque and output power of the AFPM also decrease at higher speed above the base speed due to the decrease in magnetic permeability because, typically, when the iron loss of an SMC decreases, the permeability also decreases. In this paper, many virtual SMC materials with different iron loss and permeability are used for finite element analysis of the proposed AFPM in order to clarify the sensitivity to SMC characteristics. First, the impact of the permeability on the torque and output power is investigated because the output power is very important in traction applications. Additionally, the total energy loss of AFPMs employing various SMCs is evaluated using the WLTC driving cycle. Furthermore, accuracy of simulation is evaluated using experiments of downscaled and actual size prototypes employing some SMC materials. Finally, this paper shows the newly developed SMC materials and discusses suitable SMC properties from the perspective of efficiency and output power in traction applications. en-copyright= kn-copyright= en-aut-name=TsunataRen en-aut-sei=Tsunata en-aut-mei=Ren kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=TakemotoMasatsugu en-aut-sei=Takemoto en-aut-mei=Masatsugu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=ImaiJun en-aut-sei=Imai en-aut-mei=Jun kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=SaitoTatsuya en-aut-sei=Saito en-aut-mei=Tatsuya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=UenoTomoyuki en-aut-sei=Ueno en-aut-mei=Tomoyuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= affil-num=1 en-affil=Division of Industrial Innovation Sciences Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Division of Industrial Innovation Sciences Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Division of Industrial Innovation Sciences Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Sumitomo Electric Industries Ltd. kn-affil= affil-num=5 en-affil=Sumitomo Electric Industries Ltd. kn-affil= en-keyword=Axial gap electrical machine kn-keyword=Axial gap electrical machine en-keyword=axial flux electrical machine kn-keyword=axial flux electrical machine en-keyword=traction applications kn-keyword=traction applications en-keyword=soft magnetic composite (SMC) kn-keyword=soft magnetic composite (SMC) en-keyword=WLTC cycle kn-keyword=WLTC cycle en-keyword=ferrite magnet kn-keyword=ferrite magnet en-keyword=carbon fiber rotor kn-keyword=carbon fiber rotor en-keyword=output power kn-keyword=output power en-keyword=permanent magnet kn-keyword=permanent magnet END start-ver=1.4 cd-journal=joma no-vol=6 cd-vols= no-issue= article-no= start-page=1370 end-page=1386 dt-received= dt-revised= dt-accepted= dt-pub-year=2025 dt-pub=20250815 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Time-Efficient and Practical Design Method for Skewed PMSMs: Integrating Numerical Calculations With Limited 3-D-FEA en-subtitle= kn-subtitle= en-abstract= kn-abstract=This article proposes a time-efficient and practical design method for determining appropriate skew structures for permanent magnet synchronous motors (PMSMs). Various PMSMs use skew to suppress torque ripple, but 3-D finite element analysis (3-D-FEA) is required in order to accurately determine an appropriate structure for skewed PMSMs, resulting in a long analysis time. Therefore, this article constructs a hybrid analysis method that combines numerical calculations and minimal 3-D-FEA. The aim of this method is to be practical and easy to use, even for novice designers, and to accurately and quickly design skewed PMSMs. In this article, the effectiveness of the proposed method is clarified through several case studies, and then, a skewed PMSM designed using the proposed method is verified experimentally. It is also revealed that suppression of voltage harmonics contributes to improving the performance of PMSMs in experiments. en-copyright= kn-copyright= en-aut-name=TsunataRen en-aut-sei=Tsunata en-aut-mei=Ren kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=IchimuraYu en-aut-sei=Ichimura en-aut-mei=Yu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=TakemotoMasatsugu en-aut-sei=Takemoto en-aut-mei=Masatsugu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=ImaiJun en-aut-sei=Imai en-aut-mei=Jun kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= en-keyword=Design method kn-keyword=Design method en-keyword=efficiency kn-keyword=efficiency en-keyword=field weakening control kn-keyword=field weakening control en-keyword=interior permanent magnet synchronous motor (IPMSM) kn-keyword=interior permanent magnet synchronous motor (IPMSM) en-keyword=PMSMs kn-keyword=PMSMs en-keyword=skew kn-keyword=skew en-keyword=torque ripple kn-keyword=torque ripple en-keyword=voltage harmonics kn-keyword=voltage harmonics END start-ver=1.4 cd-journal=joma no-vol=13 cd-vols= no-issue= article-no= start-page=113544 end-page=113556 dt-received= dt-revised= dt-accepted= dt-pub-year=2025 dt-pub=20250630 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Optimized Ensemble Deep Learning for Real-Time Intrusion Detection on Resource-Constrained Raspberry Pi Devices en-subtitle= kn-subtitle= en-abstract= kn-abstract=The rapid growth of Internet of Things (IoT) networks has increased security risks, making it essential to have effective Intrusion Detection Systems (IDS) for real-time threat detection. Deep learning techniques offer promising solutions for such detection due to their superior complex pattern recognition and anomaly detection capabilities in large datasets. This paper proposes an optimized ensemble-based IDS designed specifically for efficient deployment on edge hardware. However, deploying such computationally intensive models on resource-limited edge devices remains a significant challenge due to model size and computational overhead on devices with limited processing capabilities. Building upon our previously developed stacked Long Short-Term Memory (LSTM) model integrated with ANOVA feature selection, we optimize it by integrating dual-stage model compression: pruning and quantization to create a lightweight model suitable for real-time inference on Raspberry Pi devices. To evaluate the system under realistic conditions, we combined with a Kafka-based testbed to simulate dynamic IoT environments with variable traffic loads, delays, and multiple simultaneous attack sources. This enables the assessment of detection performance under varying traffic volumes, latency, and overlapping attack scenarios. The proposed system maintains high detection performance with accuracy of 97.3% across all test scenarios, while efficiently leveraging multi-core processing with peak CPU usage reaching 111.8%. These results demonstrate the systemfs practical viability for real-time IoT security at the edge. en-copyright= kn-copyright= en-aut-name=MusthafaMuhammad Bisri en-aut-sei=Musthafa en-aut-mei=Muhammad Bisri kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=HudaSamsul en-aut-sei=Huda en-aut-mei=Samsul kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=NguyenTuy Tan en-aut-sei=Nguyen en-aut-mei=Tuy Tan kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=KoderaYuta en-aut-sei=Kodera en-aut-mei=Yuta kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=NogamiYasuyuki en-aut-sei=Nogami en-aut-mei=Yasuyuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= affil-num=1 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Interdisciplinary Education and Research Field, Okayama University kn-affil= affil-num=3 en-affil=School of Informatics, Computing, and Cyber Systems, Northern Arizona University kn-affil= affil-num=4 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=5 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= en-keyword=Internet of things kn-keyword=Internet of things en-keyword=intrusion detection system kn-keyword=intrusion detection system en-keyword=stacked lstm kn-keyword=stacked lstm en-keyword=pruning model kn-keyword=pruning model en-keyword=optimizing model kn-keyword=optimizing model en-keyword=quantization model kn-keyword=quantization model en-keyword=raspberry pi kn-keyword=raspberry pi en-keyword=real-time detection kn-keyword=real-time detection en-keyword=apache kafka kn-keyword=apache kafka END start-ver=1.4 cd-journal=joma no-vol=13 cd-vols= no-issue= article-no= start-page=89003 end-page=89024 dt-received= dt-revised= dt-accepted= dt-pub-year=2025 dt-pub=20250519 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Security in Post-Quantum Era: A Comprehensive Survey on Lattice-Based Algorithms en-subtitle= kn-subtitle= en-abstract= kn-abstract=Lattice-based post-quantum cryptography (PQC) has attracted significant attention as a promising solution to the security challenges posed by quantum computing. Unlike traditional cryptographic algorithms, lattice-based schemes are expected to remain secure even in the presence of quantum attacks, making them essential for securing future data. Despite their strong theoretical foundations, lattice-based schemes face several practical challenges, particularly in optimizing performance and scalability for real-world applications. This survey provides a novel taxonomy that categorizes lattice-based PQC designs, with an emphasis on computational paradigms and security considerations. We systematically evaluate lattice-based PQC implementations across both software platforms, including central processing units and graphics processing units, as well as hardware platforms like field-programmable gate arrays and application-specific integrated circuits, highlighting their strengths and limitations. In addition, we explore the practical applications of lattice-based cryptography in fields such as secure communication, critical infrastructure, privacy-preserving data analytics, artificial intelligence, and trust and authentication systems. By offering a comprehensive overview of the current state of lattice-based PQC, this survey aims to provide valuable insights into the ongoing advancements and future research directions in the field as we transition to a post-quantum era. en-copyright= kn-copyright= en-aut-name=NguyenHien en-aut-sei=Nguyen en-aut-mei=Hien kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=HudaSamsul en-aut-sei=Huda en-aut-mei=Samsul kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=NogamiYasuyuki en-aut-sei=Nogami en-aut-mei=Yasuyuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=NguyenTuy Tan en-aut-sei=Nguyen en-aut-mei=Tuy Tan kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=School of Informatics, Computing, and Cyber Systems, Northern Arizona University kn-affil= affil-num=2 en-affil=Interdisciplinary Education and Research Field, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=School of Informatics, Computing, and Cyber Systems, Northern Arizona University kn-affil= en-keyword=Post-quantum cryptography kn-keyword=Post-quantum cryptography en-keyword=lattice-based cryptography kn-keyword=lattice-based cryptography en-keyword=number theoretic transform kn-keyword=number theoretic transform en-keyword=hardware and software implementation kn-keyword=hardware and software implementation END start-ver=1.4 cd-journal=joma no-vol=E108-B cd-vols= no-issue=1 article-no= start-page=1 end-page=13 dt-received= dt-revised= dt-accepted= dt-pub-year=2024 dt-pub=20240801 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Overloaded MIMO Spatial Multiplexing Independent of Antenna Setups en-subtitle= kn-subtitle= en-abstract= kn-abstract=This paper proposes overloaded MIMO spatial multiplexing that can increase the number of spatially multiplexed signal streams despite of the number of antennas on a terminal and that on a receiver. We propose extension of the channel matrix for the spatial multiplexing to achieve the superb multiplexing performance. Precoding based on the extended channel matrix plays a crucial role in carrying out such spatial multiplexing. We consider three types of QR-decomposition techniques for the proposed spatial multiplexing to improve the transmission performance. The transmission performance of the proposed spatial multiplexing is evaluated by computer simulation. The simulation reveals that the proposed overloaded MIMO spatial multiplexing can implement 6 stream-spatial multiplexing in a 2~2 MIMO system, i.e., the overloading ratio of 3.0. The superior transmission performance is achieved by the proposed overloaded MIMO spatial multiplexing with one of the QR-decomposition techniques. en-copyright= kn-copyright= en-aut-name=DennoSatoshi en-aut-sei=Denno en-aut-mei=Satoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=SugimotoTakumi en-aut-sei=Sugimoto en-aut-mei=Takumi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=MatobaKoki en-aut-sei=Matoba en-aut-mei=Koki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=HouYafei en-aut-sei=Hou en-aut-mei=Yafei kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=Faculty of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Faculty of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= en-keyword=overloaded MIMO kn-keyword=overloaded MIMO en-keyword=spatial multiplexing kn-keyword=spatial multiplexing en-keyword=QR-decomposition kn-keyword=QR-decomposition en-keyword=precoding kn-keyword=precoding en-keyword=overloading ratio kn-keyword=overloading ratio END start-ver=1.4 cd-journal=joma no-vol=12 cd-vols= no-issue= article-no= start-page=78366 end-page=78378 dt-received= dt-revised= dt-accepted= dt-pub-year=2024 dt-pub=2024 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Aromug: A Mug-Type Olfactory Interface to Enhance the Sweetness Perception of Beverages en-subtitle= kn-subtitle= en-abstract= kn-abstract=Sugary beverages are a significant contributor to sugar consumption, and their excessive consumption is associated with increased risks of elevated blood glucose levels and diabetes. Many individuals have a strong preference for sugary beverages and often find beverages with lower sugar content to be less satisfying. Attempts to switch to less sugary options are frequently short-lived, leading to a return to higher-sugar beverages. Recognizing that 75 ? 95% of taste perception is influenced by scent, we investigated a scent-based approach to reduce sugar intake while preserving the perception of sweetness. This study introduces an olfactory interface in the form of a mug named gAromug,h designed to emit a sweet scent in sync with the drinking action. Aromug incorporates motion sensing and scent presentation functions to enhance the perceived sweetness of a beverage, thereby encouraging a gradual reduction in sugar intake. Our experiments, involving 33 participants, demonstrated that the combined scents of sugar-free coffee and chocolate increased the perception of sweetness (p =1.641~10?2 ). The study also found that the simultaneous presentation of scent and visual cues improved taste satisfaction and sweetness perception. Additionally, we observed variations in sweetness preference related to age and frequency of coffee consumption. It was particularly observed that people in their 20s and those who frequently drink coffee tend to perceive the taste of beverages as sweeter. This suggests a potential for Aromug to customize the scent experience based on individual preferences, offering a novel way to encourage healthier beverage choices. en-copyright= kn-copyright= en-aut-name=MayumiDaiki en-aut-sei=Mayumi en-aut-mei=Daiki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=NakamuraYugo en-aut-sei=Nakamura en-aut-mei=Yugo kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=MatsudaYuki en-aut-sei=Matsuda en-aut-mei=Yuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=MisakiShinya en-aut-sei=Misaki en-aut-mei=Shinya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=YasumotoKeiichi en-aut-sei=Yasumoto en-aut-mei=Keiichi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= affil-num=1 en-affil=Graduate School of Science and Technology, Nara Institute of Science and Technology kn-affil= affil-num=2 en-affil=Faculty of Information Science and Electrical Engineering, Kyushu University kn-affil= affil-num=3 en-affil=Faculty of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Graduate School of Science and Technology, Nara Institute of Science and Technology kn-affil= affil-num=5 en-affil=Graduate School of Science and Technology, Nara Institute of Science and Technology kn-affil= en-keyword=Olfaction kn-keyword=Olfaction en-keyword=olfactory interfaces kn-keyword=olfactory interfaces en-keyword=olfactory display kn-keyword=olfactory display en-keyword=scents kn-keyword=scents en-keyword=taste evaluation kn-keyword=taste evaluation en-keyword=smell kn-keyword=smell en-keyword=olfactory perception kn-keyword=olfactory perception en-keyword=behavior change support kn-keyword=behavior change support END start-ver=1.4 cd-journal=joma no-vol=60 cd-vols= no-issue=5 article-no= start-page=6736 end-page=6751 dt-received= dt-revised= dt-accepted= dt-pub-year=2024 dt-pub=202409 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Superior Efficiency Under PWM Harmonic Current in an Axial-Flux PM Machine for HEV/EV Traction: Comparison With a Radial-Flux PM Machine en-subtitle= kn-subtitle= en-abstract= kn-abstract=This paper evaluates the harmonic current caused by a pulse width modulation (PWM) inverter and how it affects the efficiency of a novel axial-flux permanent-magnet machine using a ferrite permanent magnet (AF-FePM) in traction applications. First, differences between the finite element analysis (FEA) and experimental results are discussed using a prototype of the proposed AF-FePM. Second, the AF-FePM is compared with a commercially available radial-flux permanent-magnet machine using a Nd-sintered magnet (RF-NdPM). For both machines, the efficiency and loss are calculated using FEA when applying the sinusoidal and harmonic currents. Additionally, we present the superior efficiency of the AF-FePM under the PWM harmonic current during a WLTC driving cycle because the designed model employs the ferrite magnet and a round copper wire, unlike the RF-NdPM. Finally, motor and inverter losses at different switching frequencies are also evaluated. This paper eventually shows that the proposed AF-FePM would be one of the suitable candidates to enhance high efficiency under PWM harmonic current condition based on comprehensive discussion. en-copyright= kn-copyright= en-aut-name=TsunataRen en-aut-sei=Tsunata en-aut-mei=Ren kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=TakemotoMasatsugu en-aut-sei=Takemoto en-aut-mei=Masatsugu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=ImaiJun en-aut-sei=Imai en-aut-mei=Jun kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=SaitoTatsuya en-aut-sei=Saito en-aut-mei=Tatsuya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=UenoTomoyuki en-aut-sei=Ueno en-aut-mei=Tomoyuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= affil-num=1 en-affil=Division of Industrial Innovation Sciences Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Division of Industrial Innovation Sciences Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Division of Industrial Innovation Sciences Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Sumitomo Electric Industries Ltd. kn-affil= affil-num=5 en-affil=Sumitomo Electric Industries Ltd. kn-affil= en-keyword=Axial gap motor kn-keyword=Axial gap motor en-keyword=axial-flux machine kn-keyword=axial-flux machine en-keyword=carbon-fiber-reinforced plastic kn-keyword=carbon-fiber-reinforced plastic en-keyword=ferrite magnet kn-keyword=ferrite magnet en-keyword=iron loss kn-keyword=iron loss en-keyword=PWM drive kn-keyword=PWM drive en-keyword=PWM harmonic current kn-keyword=PWM harmonic current en-keyword=radial-flux machine kn-keyword=radial-flux machine en-keyword=soft magnetic composite kn-keyword=soft magnetic composite en-keyword=switching frequency kn-keyword=switching frequency en-keyword=WLTC drive kn-keyword=WLTC drive END start-ver=1.4 cd-journal=joma no-vol=60 cd-vols= no-issue=3 article-no= start-page=3934 end-page=3949 dt-received= dt-revised= dt-accepted= dt-pub-year=2024 dt-pub=20240301 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Designing and Prototyping an Axial-Flux Machine Using Ferrite PM and Round Wire for Traction Applications: Comparison With a Radial-Flux Machine Using Nd-Fe-B PM and Rectangular Wire en-subtitle= kn-subtitle= en-abstract= kn-abstract=This paper proposes a novel axial-flux permanent magnet machine (AFPM) employing ferrite permanent magnets (PMs) and round copper wire. The proposed AFPM adopts a novel rotor structure and uses tooth-tips with a suitable trapezoidal shape. These structures compensate for the low magnetomotive force of the round copper wire and ferrite PMs, achieving high performance at low cost. Additionally, compared with an off-the-shelf radial-flux permanent magnet machine (RFPM) using Nd-sintered PMs and rectangular copper wire, the proposed AFPM achieves the same output power and higher efficiency, despite using ferrite PMs and the round copper wire. Finally, a prototype of the proposed AFPM was manufactured and evaluated experimentally. The prototype achieved a high efficiency of over 95% across a wide operating area while maintaining required maximum torque, suggesting its potential for traction applications. en-copyright= kn-copyright= en-aut-name=TsunataRen en-aut-sei=Tsunata en-aut-mei=Ren kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=IzumiyaKosuke en-aut-sei=Izumiya en-aut-mei=Kosuke kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=TakemotoMasatsugu en-aut-sei=Takemoto en-aut-mei=Masatsugu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=ImaiJun en-aut-sei=Imai en-aut-mei=Jun kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=SaitoTatsuya en-aut-sei=Saito en-aut-mei=Tatsuya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= en-aut-name=UenoTomoyuki en-aut-sei=Ueno en-aut-mei=Tomoyuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=6 ORCID= affil-num=1 en-affil=Division of Industrial Innovation Sciences Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Division of Industrial Innovation Sciences Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Division of Industrial Innovation Sciences Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Division of Industrial Innovation Sciences Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=5 en-affil=Sumitomo Electric Industries Ltd. kn-affil= affil-num=6 en-affil=Sumitomo Electric Industries Ltd. kn-affil= en-keyword=Axial gap motor kn-keyword=Axial gap motor en-keyword=axial-flux machine kn-keyword=axial-flux machine en-keyword=carbon fiber rotor kn-keyword=carbon fiber rotor en-keyword=carbon fiber-reinforced plastic kn-keyword=carbon fiber-reinforced plastic en-keyword=city commuter kn-keyword=city commuter en-keyword=ferrite magnet kn-keyword=ferrite magnet en-keyword=flat copper wire kn-keyword=flat copper wire en-keyword=high circumferential speed kn-keyword=high circumferential speed en-keyword=radial-flux machine kn-keyword=radial-flux machine END start-ver=1.4 cd-journal=joma no-vol=E107-B cd-vols= no-issue=3 article-no= start-page=339 end-page=348 dt-received= dt-revised= dt-accepted= dt-pub-year=2024 dt-pub=202403 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Low Complexity Overloaded MIMO Non-Linear Detector with Iterative LLR Estimation en-subtitle= kn-subtitle= en-abstract= kn-abstract=This paper proposes a non-linear overloaded MIMO detector that outperforms the conventional soft-input maximum likelihood detector (MLD) with less computational complexity. We propose iterative log-likelihood ratio (LLR) estimation and multi stage LLR estimation for the proposed detector to achieve such superior performance. While the iterative LLR estimation achieves better BER performance, the multi stage LLR estimation makes the detector less complex than the conventional soft-input maximum likelihood detector (MLD). The computer simulation reveals that the proposed detector achieves about 0.6 dB better BER performance than the soft-input MLD with about half of the soft-input MLD's complexity in a 6 ~ 3 overloaded MIMO OFDM system. en-copyright= kn-copyright= en-aut-name=DennoSatoshi en-aut-sei=Denno en-aut-mei=Satoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=MakabeShuhei en-aut-sei=Makabe en-aut-mei=Shuhei kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=HouYafei en-aut-sei=Hou en-aut-mei=Yafei kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= affil-num=1 en-affil=Faculty of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Faculty of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Faculty of Environmental, Life, Natural Science and Technology, Okayama University kn-affil= en-keyword=overloaded MIMO kn-keyword=overloaded MIMO en-keyword=non-linear detector kn-keyword=non-linear detector en-keyword=soft-input decoding kn-keyword=soft-input decoding en-keyword=noise cancellation kn-keyword=noise cancellation en-keyword=ordering kn-keyword=ordering en-keyword=complexity reduction kn-keyword=complexity reduction END start-ver=1.4 cd-journal=joma no-vol=59 cd-vols= no-issue=3 article-no= start-page=3353 end-page=3367 dt-received= dt-revised= dt-accepted= dt-pub-year=2023 dt-pub=20230313 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Comparison of Thermal Characteristics in Various Aspect Ratios for Radial-Flux and Axial-Flux Permanent Magnet Machines en-subtitle= kn-subtitle= en-abstract= kn-abstract=This paper proposes an axial-flux permanent magnet machine (AFPM) that uses a neodymium-bonded permanent magnet (Nd-bonded PM) and a coreless rotor structure and assesses how it performs in industrial applications requiring high efficiency and low cost. The AFPM is able to achieve high efficiency in high-speed regions because its Nd-bonded PM can restrain eddy current loss. Additionally, the AFPM can continuously function at the rated operating point without a cooling system, so the expenses for one can be eliminated. Hence, the AFPM can simultaneously achieve high efficiency and low-cost mass production. In this paper, a comprehensive comparison including the thermal characteristics of the proposed AFPM and a conventional radial-flux permanent magnet machine (RFPM) is shown. Furthermore, this paper also focuses on how the aspect ratio influences the thermal characteristics of both machines. Finally, the effectiveness of the proposed AFPM in industrial applications is assessed using 3D-FEA and experimental results. en-copyright= kn-copyright= en-aut-name=TsunataRen en-aut-sei=Tsunata en-aut-mei=Ren kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=TakemotoMasatsugu en-aut-sei=Takemoto en-aut-mei=Masatsugu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=ImaiJun en-aut-sei=Imai en-aut-mei=Jun kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=SaitoTatsuya en-aut-sei=Saito en-aut-mei=Tatsuya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=UenoTomoyuki en-aut-sei=Ueno en-aut-mei=Tomoyuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= affil-num=1 en-affil=Division of Industrial Innovation Sciences Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Division of Industrial Innovation Sciences Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Division of Industrial Innovation Sciences Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Sumitomo Electric Industries Ltd kn-affil= affil-num=5 en-affil=Sumitomo Electric Industries Ltd kn-affil= en-keyword=Aspect ratio kn-keyword=Aspect ratio en-keyword=axial-flux machine kn-keyword=axial-flux machine en-keyword=axial-gap motor kn-keyword=axial-gap motor en-keyword=cooling kn-keyword=cooling en-keyword=high efficiency kn-keyword=high efficiency en-keyword=mass production kn-keyword=mass production en-keyword=PMSM kn-keyword=PMSM en-keyword=radial-flux machine kn-keyword=radial-flux machine en-keyword=soft magnetic composite kn-keyword=soft magnetic composite en-keyword=thermal characteristic kn-keyword=thermal characteristic END start-ver=1.4 cd-journal=joma no-vol=11 cd-vols= no-issue= article-no= start-page=2848 end-page=2862 dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=20221228 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Novel Rotor Structure Employing Large Flux Barrier and Disproportional Airgap for Enhancing Efficiency of IPMSM Adopting Concentrated Winding Structure en-subtitle= kn-subtitle= en-abstract= kn-abstract=Interior permanent magnetic synchronous motors (IPMSMs) adopting concentrated windings have been widely used in industrial applications. To reduce operating costs, it is an important issue to enhance the efficiency of an IPMSM as much as possible while maintaining manufacturing costs. In general, an IPMSM used for an industrial application always operates in a specific operating area according to the required load. Therefore, this paper has two purposes. The first purpose is to propose a novel rotor structure which can enhance efficiency at the target wide-speed middle-torque operating area without additional manufacturing costs. The second purpose is to clarify the design method for a suitable rotor structure depending on its target operating area. Reducing losses is the key to enhancing efficiency. This paper first examines the effects of adopting large flux barriers and a disproportional airgap on copper and iron losses, and clarifies their merits and respective high-efficiency operating areas. Furthermore, to take advantage of the two rotor structures, a novel rotor structure which employs both large flux barriers and a disproportional airgap has been proposed. 2D-FEM (Finite-Element Method) is used for discussion first, and a prototype machine is manufactured to verify the 2D-FEM results. Both 2D-FEM and experimental results show that the proposed rotor structure can enhance the efficiency of an IPMSM most effectively at the target operating area. Moreover, for a low-speed high-torque operating area, adopting only large flux barriers is most suitable. And for a high-speed low-torque operating area, adopting only a disproportional airgap is most suitable. en-copyright= kn-copyright= en-aut-name=TaoXianji en-aut-sei=Tao en-aut-mei=Xianji kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=TakemotoMasatsugu en-aut-sei=Takemoto en-aut-mei=Masatsugu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=TsunataRen en-aut-sei=Tsunata en-aut-mei=Ren kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=OgasawaraSatoshi en-aut-sei=Ogasawara en-aut-mei=Satoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= affil-num=1 en-affil=Graduate School of Information and Technology, Hokkaido University kn-affil= affil-num=2 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=4 en-affil=Graduate School of Information and Technology, Hokkaido University kn-affil= en-keyword=Rotors kn-keyword=Rotors en-keyword=Magnetic flux kn-keyword=Magnetic flux en-keyword=Atmospheric modeling kn-keyword=Atmospheric modeling en-keyword=Torque kn-keyword=Torque en-keyword=Iron kn-keyword=Iron en-keyword=Copper kn-keyword=Copper en-keyword=Costs kn-keyword=Costs en-keyword=IPMSM kn-keyword=IPMSM en-keyword=concentrated winding structure kn-keyword=concentrated winding structure en-keyword=high efficiency kn-keyword=high efficiency en-keyword=flux barrier kn-keyword=flux barrier en-keyword=disproportional airgap kn-keyword=disproportional airgap END start-ver=1.4 cd-journal=joma no-vol=10 cd-vols= no-issue= article-no= start-page=134580 end-page=134591 dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=20221226 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Neg/pos-Normalized Accuracy Measures for Software Defect Prediction en-subtitle= kn-subtitle= en-abstract= kn-abstract=In evaluating the performance of software defect prediction models, accuracy measures such as precision and recall are commonly used. However, most of these measures are affected by neg/pos ratio of the data set being predicted, where neg is the number of negative cases (defect-free modules) and pos is the number of positive cases (defective modules). Thus, it is not fair to compare such values across different data sets with different neg/pos ratios and it may even lead to misleading or contradicting conclusions. The objective of this study is to address the class imbalance issue in assessing performance of defect prediction models. The proposed method relies on computation of expected values of accuracy measures based solely on the value of the neg and pos values of the data set. Based on the expected values, we derive the neg/pos-normalized accuracy measures, which are defined as their divergence from the expected value divided by the standard deviation of all possible prediction outcomes. The proposed measures enable us to provide a ranking of predictions across different data sets, which can distinguish between successful predictions and unsuccessful predictions. Our results derived from a case study of defect prediction based on 19 defect data sets indicate that ranking of predictions is significantly different than the ranking of conventional accuracy measures such as precision and recall as well as composite measures F1-value, AUC of ROC, MCC, G-mean and Balance. In addition, we conclude that MCC attains a better defect prediction accuracy than F1-value, AUC of ROC, G-mean and Balance. en-copyright= kn-copyright= en-aut-name=GanMaohua en-aut-sei=Gan en-aut-mei=Maohua kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=YucelZeynep en-aut-sei=Yucel en-aut-mei=Zeynep kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=MondenAkito en-aut-sei=Monden en-aut-mei=Akito kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= affil-num=1 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Natural Science and Technology, Okayama University kn-affil= en-keyword=Software defect kn-keyword=Software defect en-keyword=defect prediction model kn-keyword=defect prediction model en-keyword=accuracy measure kn-keyword=accuracy measure en-keyword=classification technology kn-keyword=classification technology en-keyword=empirical software engineering kn-keyword=empirical software engineering END start-ver=1.4 cd-journal=joma no-vol=58 cd-vols= no-issue=3 article-no= start-page=3470 end-page=3485 dt-received= dt-revised= dt-accepted= dt-pub-year=2022 dt-pub=20225 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=SMC Development Guidelines for Axial Flux PM Machines Employing Coreless Rotor Structure for Enhancing Efficiency Based on Experimental Results en-subtitle= kn-subtitle= en-abstract= kn-abstract=In recent years, there has been growing demand for flat electrical machines in order to minimize system size while also maintaining high efficiency. In general, axial flux machines (AFMs) are more suitable for flat form than radial flux machines (RFMs). AFMs usually employ a soft magnetic composite (SMC) for the stator core, and their efficiency can be improved by employing an SMC that has low iron loss. However, this reduces the average torque because there is generally a tradeoff relationship between iron loss and magnetic permeability in SMCs. This article, therefore, proposes an AFM with a coreless rotor structure in which the torque performance is not easily affected by the permeability of the SMC. This article aims to reveal the ideal SMC characteristics for high efficiency in AFMs. First, many virtual SMC materials with different iron loss and permeability are used for simulations of AFMs in order to investigate sensitivity to material properties. The simulations by virtual SMCs take into account the experimental increase in the iron loss. As a result, guidelines for developing SMCs are constructed based on the experimental results. Finally, prototype AFMs employing new SMCs developed by following the guidelines are shown, and it is found that they offer higher efficiency in all operating area than conventional AFMs. In particular, one prototype achieves an extremely high efficiency of over 96% at 6000 r/min, 0.8 Nm in experiments. en-copyright= kn-copyright= en-aut-name=TsunataRen en-aut-sei=Tsunata en-aut-mei=Ren kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=TakemotoMasatsugu en-aut-sei=Takemoto en-aut-mei=Masatsugu kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= en-aut-name=OgasawaraSatoshi en-aut-sei=Ogasawara en-aut-mei=Satoshi kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=3 ORCID= en-aut-name=SaitoTatsuya en-aut-sei=Saito en-aut-mei=Tatsuya kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=4 ORCID= en-aut-name=UenoTomoyuki en-aut-sei=Ueno en-aut-mei=Tomoyuki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=5 ORCID= affil-num=1 en-affil=Division of Industrial Innovation Sciences Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=2 en-affil=Division of Industrial Innovation Sciences Graduate School of Natural Science and Technology, Okayama University kn-affil= affil-num=3 en-affil=Graduate School of Information Science and Technology, Hokkaido University kn-affil= affil-num=4 en-affil=Sumitomo Electric Industries Ltd. kn-affil= affil-num=5 en-affil=Sumitomo Electric Industries Ltd. kn-affil= END start-ver=1.4 cd-journal=joma no-vol=9 cd-vols= no-issue= article-no= start-page=111651 end-page=111665 dt-received= dt-revised= dt-accepted= dt-pub-year=2021 dt-pub=2021 dt-online= en-article= kn-article= en-subject= kn-subject= en-title= kn-title=Mitigation of Kernel Memory Corruption Using Multiple Kernel Memory Mechanism en-subtitle= kn-subtitle= en-abstract= kn-abstract=Operating systems adopt kernel protection methods (e.g., mandatory access control, kernel address space layout randomization, control flow integrity, and kernel page table isolation) as essential countermeasures to reduce the likelihood of kernel vulnerability attacks. However, kernel memory corruption can still occur via the execution of malicious kernel code at the kernel layer. This is because the vulnerable kernel code and the attack target kernel code or kernel data are located in the same kernel address space. To gain complete control of a host, adversaries focus on kernel code invocations, such as function pointers that rely on the starting points of the kernel protection methods. To mitigate such subversion attacks, this paper presents multiple kernel memory (MKM), which employs an alternative design for kernel address space separation. The MKM mechanism focuses on the isolation granularity of the kernel address space during each execution of the kernel code. MKM provides two kernel address spaces, namely, i) the trampoline kernel address space, which acts as the gateway feature between user and kernel modes and ii) the security kernel address space, which utilizes the localization of the kernel protection methods (i.e., kernel observation). Additionally, MKM achieves the encapsulation of the vulnerable kernel code to prevent access to the kernel code invocations of the separated kernel address space. The evaluation results demonstrated that MKM can protect the kernel code and kernel data from a proof-of-concept kernel vulnerability that could lead to kernel memory corruption. In addition, the performance results of MKM indicate that the system call overhead latency ranges from 0.020 ƒĘs to 0.5445 ƒĘs, while the web application benchmark ranges from 196.27 ƒĘs to 6, 685.73 ƒĘs for each download access of 100,000 Hypertext Transfer Protocol sessions. MKM attained a 97.65% system benchmark score and a 99.76% kernel compilation time. en-copyright= kn-copyright= en-aut-name=KuzunoHiroki en-aut-sei=Kuzuno en-aut-mei=Hiroki kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=1 ORCID= en-aut-name=YamauchiToshihiro en-aut-sei=Yamauchi en-aut-mei=Toshihiro kn-aut-name= kn-aut-sei= kn-aut-mei= aut-affil-num=2 ORCID= affil-num=1 en-affil=1Intelligent Systems Laboratory, SECOM Company Ltd. kn-affil= affil-num=2 en-affil=2Graduate School of Natural Science and Technology, Okayama University kn-affil= en-keyword=Memory corruption kn-keyword=Memory corruption en-keyword=kernel vulnerability kn-keyword=kernel vulnerability en-keyword=system security kn-keyword=system security en-keyword=operating system kn-keyword=operating system END