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Optimal design of auxiliary-teeth to solve circulation current reduction of permanent magnet linear synchronous motor

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Journal of Central South University 2011年第3期18卷 690-696页

作者： JANG Ki-bong kim Jee-hyun AN Ho-jin kim gyu-tak School of Mechatronics Changwon National University

A discontinuity of magnetic circuits according to the end effect is generated in the permanent magnet linear synchronous motor （PMLSM）. Due to the unbalanced back electro-motive force （EMF） and impedance produced, unbalanced current is generated. The cireulatin8 current, which is caused by a decrease in the thrust, is generated by the unbalanced current. The optimal design of auxiliary-teeth at the end of the mover was carried out to solve the unbalance of phase by using design of experiment （DOE）, and compared with the basic model through finite element analysis （FEA）. As a result, the auxiliary-teeth model compensates for the decrease of thrust caused by the unbalanced phase. Also, this model is proven to reduce the detent force by the vibration and noise of the PMLSM and copper loss caused by the circulating current.

关键词： permanent magnet linear synchronous motor auxiliary-teeth circulation current end effect thrust reduction

Optimal design of FRMSM to decrease detent force

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Journal of Central South University 2011年第2期18卷 458-464页

作者： JANG Ki-Bong PYO Se-Ho AN Ho-Jin kim gyu-tak School of Mechatronics Changwon National University

An optimal configuration of the flux-reversal linear synchronous motor (FRLSM) with the optimal number of attachment permanent magnets (PMs) was presented. The optimal model of 2 000 N was designed to reduce the detent force by redesigning the air-gap structure and skewing. The design parameters,mover PMs and stator core,were selected for optimal design by DOE. The thrust and the detent force of the designed optimal models were compared by finite element analysis (FEA). As a result,the thrust of the optimal model is slightly decreased by 1.97% compared with the basic model,and the detent force of the optimal model is greatly decreased by 88.47% compared with the basic model.

关键词： flux-reversal linear synchronous motor detent force thrust design of experiment skew and overhang

Optimization of rotor shape for constant torque improvement and radial magnetic force minimization

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Journal of Central South University 2012年第2期19卷 357-364页

作者： CHO gyu-won WOO Seok-hyun JI Seung-hun PARK Kyoung-won JANG Ki-bong kim gyu-tak School of Mechatronics Changwon National University

The design of notch and barrier was optimized in order to improve the characteristics of constant torque while minimizing the cogging torque that occurs as a result of teeth and slot structure. The barrier was installed in order to minimize the cogging torque and torque ripple by finite element method (FEM) with a reduced barrier width toward the center of magnetic pole. The position and width of notch, which can offset cogging torque, can be calculated with energy distribution of air-gap using Fourier series. The optimized model demonstrates a 60% decrease in the cogging torque, a 75.3% decrease in the torque ripple and a 3% increase in the operating torque when compared with the basic model.

关键词： permanent magnet synchronous motor barrier notch radial magnetic force cogging torque

Postmortem ^(7)Li NMR analysis for assessing the reversibility of lithium metal electrodes in lithium metal batteries

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Journal of Energy Chemistry 2024年第7期94卷 430-440页

作者： Jaewon Baek Sunha kim Hee-tak kim Oc Hee Han Department of Chemical&Biomolecular Engineering KAISTDaejeon 34141Republic of Korea Metropolitan Seoul Center Korea Basic Science InstituteSeoul 03759Republic of Korea Graduate School of Analytical Science&Technology Chungnam National UniversityDaejeon 34134Republic of Korea

Despite the proficiency of lithium(Li)-7 NMR spectroscopy in delineating the physical and chemical states of Li metal electrodes,challenges in specimen preparation and interpretation impede its *** this study,we conducted a comprehensive postmortem analysis utilizing ^(7)Li NMR,employing a stan-dard magic angle spinning probe to examine protective-layer coated Li metal electrodes and LiAg alloy electrodes against bare Li metal electrodes within Li metal batteries(LMBs).Our investigation explores the effects of sample burrs,alignment with the magnetic field,the existence of liquid electrolytes,and precycling on the ^(7)Li NMR *** contrasting NMR spectra before and after cycling,we identi-fied alterations in Li^(0) and Li^(+) signals attributable to the degradation of the Li metal *** NMR analyses decisively demonstrate the efficacy of the protective layer in mitigating dendrite and solid elec-trolyte interphase ***,we noted that Li*ions near the Li metal surface exhibit magnetic susceptibility anisotropy,revealing a novel approach to studying diamagnetic species on Li metal elec-trodes in *** study provides valuable insights and practical guidelines for characterizing distinct lithium states within LMBs.

关键词： NMR spectroscopy Lithium-7 Lithium metal battery Electrolyte Electrode-protective layer Solid electrolyte interface Magnetic susceptibility anisotropy Lithium-metal NMR signal Diamagnetic^(7)Li NMR signal

Anomaly Detection in Imbalanced Encrypted Traffic with Few Packet Metadata-Based Feature Extraction

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Computer Modeling in Engineering & Sciences 2024年第10期141卷 585-607页

作者： Min-gyu kim Hwankuk kim Department of Financial Information Security Kookmin UniversitySeoul02707Republic of Korea Department of Information Security Cryptography Mathematics Kookmin UniversitySeoul02707Republic of Korea

In the IoT(Internet of Things)domain,the increased use of encryption protocols such as SSL/TLS,VPN(Virtual Private Network),and Tor has led to a rise in attacks leveraging encrypted *** research on anomaly detection using AI(Artificial Intelligence)is actively progressing,the encrypted nature of the data poses challenges for labeling,resulting in data imbalance and biased feature extraction toward specific *** study proposes a reconstruction error-based anomaly detection method using an autoencoder(AE)that utilizes packet metadata excluding specific node *** proposed method omits biased packet metadata such as IP and Port and trains the detection model using only normal data,leveraging a small amount of packet *** makes it well-suited for direct application in IoT environments due to its low resource *** experiments comparing feature extraction methods for AE-based anomaly detection,we found that using flowbased features significantly improves accuracy,precision,F1 score,and AUC(Area Under the Receiver Operating Characteristic Curve)score compared to packet-based ***,for flow-based features,the proposed method showed a 30.17%increase in F1 score and improved false positive rates compared to Isolation Forest and ***,the proposedmethod demonstrated a 32.43%higherAUCwhen using packet features and a 111.39%higher AUC when using flow features,compared to previously proposed oversampling *** study highlights the impact of feature extraction methods on attack detection in imbalanced,encrypted traffic environments and emphasizes that the one-class method using AE is more effective for attack detection and reducing false positives compared to traditional oversampling methods.

关键词： One-class anomaly detection feature extraction auto-encoder encrypted traffic CICIoT2023

Defect Detection Model Using Time Series Data Augmentation and Transformation

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Computers, Materials & Continua 2024年第2期78卷 1713-1730页

作者： gyu-Il kim Hyun Yoo Han-Jin Cho Kyungyong Chung Department of Computer Science Kyonggi UniversitySuwon-si16227Korea Contents Convergence Software Research Institue Kyonggi UniversitySuwon-si16227Korea Department of Energy IT Engineering Far East UniversityEumsung-gun27601Korea Division of AI Computer Science and Engineering Kyonggi UniversitySuwon-si16227Korea

Time-series data provide important information in many fields,and their processing and analysis have been the focus of much ***,detecting anomalies is very difficult due to data imbalance,temporal dependence,and ***,methodologies for data augmentation and conversion of time series data into images for analysis have been *** paper proposes a fault detection model that uses time series data augmentation and transformation to address the problems of data imbalance,temporal dependence,and robustness to *** method of data augmentation is set as the addition of *** involves adding Gaussian noise,with the noise level set to 0.002,to maximize the generalization performance of the *** addition,we use the Markov Transition Field(MTF)method to effectively visualize the dynamic transitions of the data while converting the time series data into *** enables the identification of patterns in time series data and assists in capturing the sequential dependencies of the *** anomaly detection,the PatchCore model is applied to show excellent performance,and the detected anomaly areas are represented as heat *** allows for the detection of anomalies,and by applying an anomaly map to the original image,it is possible to capture the areas where anomalies *** performance evaluation shows that both F1-score and Accuracy are high when time series data is converted to ***,when processed as images rather than as time series data,there was a significant reduction in both the size of the data and the training *** proposed method can provide an important springboard for research in the field of anomaly detection using time series ***,it helps solve problems such as analyzing complex patterns in data lightweight.

关键词： Defect detection time series deep learning data augmentation data transformation

Tuning electronic structure of RuO_(2)by single atom Zn and oxygen vacancies to boost oxygen evolution reaction in acidic medium

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Journal of Energy Chemistry 2024年第1期88卷 94-102,I0003页

作者： Qing Qin Tiantian Wang Zijian Li Guolin Zhang Haeseong Jang Liqiang Hou Yu Wang Min gyu kim Shangguo Liu Xien Liu College of Chemical Engineering Qingdao University of Science and TechnologyQingdao 266042ShandongChina Department of Chemistry City University of Hong KongHong Kong 999077China Department of Advanced Materials Engineering Chung-Ang UniversityAnseong-siGyeonggi-do 17546SeoulRepublic of Korea Beamline Research Division Pohang Accelerator Laboratory(PAL)Pohang 37673Gyeongsangbuk-doRepublic of Korea

The poor stability of RuO_(2)electrocatalysts has been the primary obstacles for their practical application in polymer electrolyte membrane *** dramatically enhance the durability of RuO_(2)to construct activity-stability trade-off model is full of significance but ***,a single atom Zn stabilized RuO_(2)with enriched oxygen vacancies(SA Zn-RuO_(2))is developed as a promising alternative to iridium oxide for acidic oxygen evolution reaction(OER).Compared with commercial RuO_(2),the enhanced Ru–O bond strength of SA Zn-RuO_(2)by forming Zn-O-Ru local structure motif is favorable to stabilize surface Ru,while the electrons transferred from Zn single atoms to adjacent Ru atoms protects the Ru active sites from ***,the optimized surrounding electronic structure of Ru sites in SA ZnRuO_(2)decreases the adsorption energies of OER intermediates to reduce the reaction *** a result,the representative SA Zn-RuO_(2)exhibits a low overpotential of 210 mV to achieve 10 mA cm^(-2)and a greatly enhanced durability than commercial RuO_(2).This work provides a promising dual-engineering strategy by coupling single atom doping and vacancy for the tradeoff of high activity and catalytic stability toward acidic OER.

关键词： Electrocatalyst Acidic oxygen evolution reaction Electronic structure engineering Durability Reaction barrier

Electron-deficient ZnO induced by heterointerface engineering as the dominant active component to boost CO_(2)-to-formate conversion

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Carbon Energy 2024年第5期6卷 127-136页

作者： Qing Qin Zijian Li Yingzheng Zhang Haeseong Jang Li Zhai Liqiang Hou Xiaoqian Wei Zhe Wang Min gyu kim Shangguo Liu Xien Liu College of Chemical Engineering Qingdao University of Science and TechnologyQingdaoChina Department of Chemistry City University of Hong KongHong Kong SARChina Department of Advanced Materials Engineering Chung-Ang UniversityAnseong-siGyeonggi-doRepublic of Korea Beamline Research Division Pohang Accelerator Laboratory(PAL)PohangRepublic of Korea

Electrocatalytic CO_(2)-to-formate conversion is considered an economically viable *** general,Zn-based nanomaterials are well-known to be highly efficient electrocatalysts for the conversion of CO_(2) to CO,but seldom do they exhibit excellent selectivity toward *** this article,we demonstrate that a heterointerface catalyst ZnO/ZnSnO3 with nanosheet morphology shows enhanced selectivity with a maximum Faradaic efficiency(FE)of 86%at−0.9 V versus reversible hydrogen electrode and larger current density for the conversion of CO_(2) to formate than pristine ZnO and *** particular,the FEs of the C1 products(CO+HCOO−)exceed 98%over the potential *** experimental measurements combined with theoretical calculations revealed that the ZnO in ZnO/ZnSnO3 heterojunction delivers the valence electron depletion and accordingly optimizes Zn d-band center,which results in moderate Zn-O hybridization of HCOO*and weakened Zn-C hybridization of competing COOH*,thus greatly boosting the HCOOH *** study highlights the importance of charge redistribution in catalysts on the selectivity of electrochemical CO_(2) reduction.

关键词： charge redistribution CO_(2)reduction reaction electrocatalyst heterointerfaces selectivity

Stable operation of highly loaded pure Si-Fe anode under ambient pressure via carboxy silane-directed robust solid electrolyte interphase

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Journal of Energy Chemistry 2024年第7期94卷 568-576页

作者： Guntae Lim Dong Guk Kang Hyeon gyu Lee Yen Hai Thi Tran Kihun An Junghyun Choi Kwang Chul Roh Do Youb kim Seung-Wan Song Department of Chemical Engineering&Applied Chemistry Chungnam National University Daejeon 34134Republic of Korea Energy Storage Materials Center Korea Institute of Ceramic Engineering&TechnologyJinju 52851Republic of Korea Advanced Energy Materials Research Center Korea Research Institute of Chemical TechnologyDaejeon 34114Republic of Korea

Incorporation of higher content Si anode material beyond 5 wt% to Li-ion batteries(LIBs)is challenging,owing to large volume change,swelling,and solid electrolyte interphase(SEI)instability ***,a strategy of diacetoxydimethylsilane(DAMS)additive-directed SEI stabilization is proposed for a stable operation of Si-0.33FeSi_(2)(named as Si-Fe)anode without graphite,which provides siloxane inorganics and organics enrichment that compensate insufficient passivation of fluoroethylene carbonate(FEC)additive and reduce a dependence on *** stable cycling performance of highly loaded(3.5 mA h cm^(-2))pure Si-Fe anode is achieved with 2 wt%DAMS combined with 9 wt%FEC additives under ambient pressure,yielding high capacity 1270 mA h g^(-1)at 0.5 C and significantly improved capacity retention of 81% after 100 cycles,whereas short circuit and rapid capacity fade occur with FEC only ***-directed robust SEI layer dramatically suppresses swelling and particles crossover through separator,and therefore prevents short circuit,demonstrating a possible operation of pure Si or Sidominant anodes in the next-generation high-energy-density and safe LIBs.

关键词： High-energy Li-ion battery Pure Si-Fe anode without graphite Silane additive SEI layer Suppressed swelling