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Development of vehicle-recognition method on water surfaces using LiDAR data:SPD^(2)(spherically stratified point projection with diameter and distance)

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Defence Technology（防务技术） 2024年第6期36卷 95-104页

作者： Eon-ho Lee Hyeon Jun Jeon Jinwoo choi Hyun-Taek choi Sejin Lee The Department of Mechanical Engineering Kongju National University1223-24 Cheonan-daeroCheonan 31080Republic of Korea Ocean System Engineering Research Division Korea Research Institute of Ships and Ocean Engineering(KRISO)Daejeon 34103Republic of Korea The Division of Mechanical&Automotive Engineering Kongju National University1223-24 Cheonan-daeroCheonan 31080Republic of Korea

Swarm robot systems are an important application of autonomous unmanned surface vehicles on water *** monitoring natural environments and conducting security activities within a certain range using a surface vehicle,the swarm robot system is more efficient than the operation of a single object as the former can reduce cost and save *** is necessary to detect adjacent surface obstacles robustly to operate a cluster of unmanned surface *** this purpose,a LiDAR(light detection and ranging)sensor is used as it can simultaneously obtain 3D information for all directions,relatively robustly and accurately,irrespective of the surrounding environmental *** the GPS(global-positioning-system)error range exists,obtaining measurements of the surface-vessel position can still ensure stability during platoon *** this study,a three-layer convolutional neural network is applied to classify types of surface *** aim of this approach is to redefine the sparse 3D point cloud data as 2D image data with a connotative meaning and subsequently utilize this transformed data for object classification ***,we have proposed a descriptor that converts the 3D point cloud data into 2D image *** use this descriptor effectively,it is necessary to perform a clustering operation that separates the point clouds for each *** developed voxel-based clustering for the point cloud ***,using the descriptor,3D point cloud data can be converted into a 2D feature image,and the converted 2D image is provided as an input value to the *** intend to verify the validity of the proposed 3D point cloud feature descriptor by using experimental data in the ***,we explore the feasibility of real-time object classification within this framework.

关键词： Object classification Clustering 3D point cloud data LiDAR(light detection and ranging) Surface vehicle

Real Time Simulation of Distribution System with Distributed Energy Resources

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Real Time Simulation of Distribution System with Distributed...

Data driven computational design of stable oxygen evolution catalysts by DFT and machine learning:Promising electrocatalysts

作者： Tran Thai Trung Seon-Ju Ahn joon-ho choi Dept. of Electrical Engineering Chonnam National University

This paper presents a real–time simulation of distribution system with distributed generation–DGs,Step voltage regulation(SVR) and battery energy storage systems(BESSs) using Real Time Digital Simulation(RTDS).The simulation models of a DG and a Nickel–Metal Hydride battery are developed as RSCAD user defined *** control schemes of DGs and BESSs to show the impacts of DGs to local voltages and BESS to accommodate the variation of DG power output are proposed and implemented as a function block in the RSCAD *** of the system implementation in RTDS are also discussed and solutions are ***,the simulation results are given out to verify the correctness of the control schemes.

关键词： RTDS distributed energy resource battery energy resource voltage control user defined model

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Journal of Energy Chemistry 2024年第4期91卷 645-655页

作者： Hwanyeol Park Yunseok Kim Seulwon choi ho Jun Kim Department of Display Materials Engineering Soonchunhyang UniversityAsanChung-nam 31538Republic of Korea Department of Electronic Materials Devicesand Equipment EngineeringSoonchunhyang Uni-versityAsanChungnam 31538Republic of Korea Department of Mechanical Engineering Hanyang University ERICA Campus55 Hanyangdaehak-roSangnok-guAnsanGyeonggi-do 15588Republic of Korea

The revolutionary development of machine learning(ML),data science,and analytics,coupled with its application in material science,stands as a significant milestone of the scientific community over the last *** active,stable,and cost-efficient catalysts is crucial for oxygen evolution reaction owing to the significance in a range of electrochemical energy co nversion *** this work,we have demonstrated an efficient approach of high-throughput screening to find stable transition metal oxides under acid condition for high-performance oxygen evolution reaction(OER)catalysts through density functional theory(DFT)calculation and a machine learning algorithm.A methodology utilizing both the Materials Project database and DFT calculations was introduced to assess the acid stability under specific reaction *** upon this,OER catalytic activity of acid-stable materials was examined,highlighting potential OER catalysts that meet the required *** identified IrO_(2),Fe(SbO_(3))_(2),Co(SbO_(3))_(2),Ni(SbO_(3))_(2),FeSbO_(4),Fe(SbO_(3))4,MoWO_(6),TiSnO_(4),CoSbO_(4),and Ti(WO_(4))_(2)as promising catalysts,several of which have already been experimentally discovered for their robust OER performance,while others are novel for experimental exploration,thereby broadening the chemical scope for efficient OER *** of the bond length of TM-O and the first ionization energy were used to unveil the OER activity *** the calculated results,guidance has been derived to effectively execute advanced high-throughput screenings for the discovery of catalysts with favorable ***,the intrinsic correlation between catalytic performance and various atomic and structural factors was elucidated using the ML *** these approaches,we not only streamline the choice of the promising electrocatalysts but also offer insights for the design of varied catalyst models and the discovery of superior c

关键词： Transition metal oxides Oxygen evolution reaction High-throughput screening First-principles calculation Machine learning

Correlation between hydration properties and electrochemical performances on Ln cation size effect in layered perovskite for protonic ceramic fuel cells

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Journal of Energy Chemistry 2024年第1期88卷 1-9,I0001页

作者： Inhyeok Cho Jiwon Yun Boseok Seong Junseok Kim Sun Hee choi ho-Il Ji Sihyuk choi Department of Mechanical Engineering Kumoh National Institute of TechnologyGumi 39177GyeongbukRepublic of Korea Department of Aeronautics Mechanical and Electronic Convergence EngineeringKumoh National Institute of TechnologyGumi 39177GyeongbukRepublic of Korea Center for Energy Materials Research Korea Institute of Science and Technology(KIST)Seoul 02792Republic of Korea Center for Hydrogen and Fuel Cell Research Clean Technology Research DivisionKorea Institute of Science and Technology(KIST)Seoul 02792Republic of Korea Department of Energy and Environmental Engineering University of Science and TechnologySeoul 02792Republic of Korea Nanomaterials Science and Engineering Korea University of Science and Technology(UST)KIST CampusSeoul 02792Republic of Korea

PrBa_(0.5)Sr_(0.5)Co_(1.5)Fe_(0.5)O_(5+δ)(PrBSCF) has attracted much research interest as a potential triple ionic and electronic conductor(TIEC) electrode for protonic ceramic fuel cells(PCFCs). The chemical formula for Pr BSCF is AA'B_(2)O_(5+δ), with Pr(A-site) and Ba/Sr(A'-site) alternately stacked along the c-axis. Due to these structural features, the bulk oxygen ion diffusivity is significantly enhanced through the disorder-free channels in the PrO layer;thus, the A site cations(lanthanide ions) play a pivotal role in determining the overall electrochemical properties of layered perovskites. Consequently, previous research has predominantly focused on the electrical properties and oxygen bulk/surface kinetics of Ln cation effects,whereas the hydration properties for PCFC systems remain unidentified. Here, we thoroughly examined the proton uptake behavior and thermodynamic parameters for the hydration reaction to conclusively determine the changes in the electrochemical performances depending on LnBa_(0.5)Sr_(0.5)Co_(1.5)Fe_(0.5)O_(5+δ)(LnBSCF,Ln=Pr, Nd, and Gd) cathodes. At 500 ℃, the quantitative proton concentration of PrBSCF was 2.04 mol% and progressively decreased as the Ln cation size decreased. Similarly, the Gibbs free energy indicated that less energy was required for the formation of protonic defects in the order of Pr BSCF hodes, PCFC single cell measurements and analysis of the distribution of relaxation time were further investigated.

关键词： Protonic ceramic fuel cell Cathode Triple ionic and electronic conductor Hydration property Proton uptake Gibbs free energy

Enhancing BiVO_(4)photoanode performance by insertion of an epitaxial BiFeO_(3)ferroelectric layer

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Journal of Energy Chemistry 2024年第2期89卷 71-78,I0003页

作者： Haejin Jang Yejoon Kim hojoong choi Jiwoong Yang Yoonsung Jung Sungkyun choi Donghyeon Lee ho Won Jang Sanghan Lee School of Materials Science and Engineering Gwangju Institute of Science and TechnologyGwangju 61005Republic of Korea Department of Materials Science and Engineering Seoul National UniversitySeoul 08826Republic of Korea

BiVO_(4)(BVO)is a promising material as the photoanode for use in photoelectrochemical ***,the high charge recombination and slow charge transfer of the BVO have been obstacles to achieving satisfactory photoelectrochemical *** address this,various modifications have been attempted,including the use of ferroelectric *** materials can form a permanent polarization within the layer,enhancing the separation and transport of photo-excited electron-hole *** this study,we propose a novel approach by depositing an epitaxial BiFeO_(3)(BFO)thin film underneath the BVO thin film(BVO/BFO)to harness the ferroelectric property of *** self-polarization of the inserted BFO thin film simultaneously functions as a buffer layer to enhance charge transport and a hole-blocking layer to reduce charge *** a result,the BVO/BFO photoanodes showed more than 3.5 times higher photocurrent density(0.65 mA cm^(-2))at 1.23 V_(RHE)under the illumination compared to the bare BVO photoanodes(0.18 m A cm^(-2)),which is consistent with the increase of the applied bias photon-to-current conversion efficiencies(ABPE)and the result of electrochemical impedance spectroscopy(EIS)*** results can be attributed to the self-polarization exhibited by the inserted BFO thin film,which promoted the charge separation and transfer efficiency of the BVO photoanodes.

关键词： Photoelectrochemical Photoanode BiVO_(4) Ferroelectric materials BiFeO_(3)

Inclusive quasielastic neutrino-nucleus scattering with energy density functional nuclear models

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Chinese Physics C 2024年第8期48卷 153-158页

作者： K.S.Kim Soonchul choi Hana Gil Chang ho Hyun School of liberal arts and science korea aerospace universitygoyang 10540korea Center for exotic nuclear studies institute for basic sciencedaejeon 34126korea Center for extreme nuclear matters korea universityseoul 02841korea Department of physics education daegu universitygyeongsan 38453korea

In this study,we calculated the inclusive charged-current neutrino-nucleus scattering from ^(40)Ar in the quasielastic *** explore the effect of uncertainties stemming from the nuclear structure,we used the KIDS(Korea-IBS-Daegu-SKKU)nuclear energy density functional and Skyrme force models,namely SLy4,SkI3,and *** models were selected to have distinct behavior in terms of the density dependence of the symmetry energy and the effective mass of the *** the charged-current neutrino scattering,the single-and double-differential cross sections were calculated for various *** cross sections are reported as a function of the incident neutrino *** theoretical cross sections were compared with experimental data,and the roles of the effective mass and symmetry energy were investigated in terms of charged-current neutrino-nucleus scattering.

关键词： energy density functional neutrino-nucleus scattering symmetry energy effective mass of the nucleon

Dynamic Modeling of DFIG Wind Farms and HVDC for the Power System in Jeju Island

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Dynamic Modeling of DFIG Wind Farms and HVDC for the Power S...

The Cause of Institutionalized Private Tutoring in Korea:Defective Public Schooling or a Universal Desire for Family Reproduction?

2011 International Conference on Advanced Power System Automation and Protection(APAP 2011)

作者： Soon-Ryul Nam Sang-Hee Kang Hae-Kon Nam joon-ho choi Myongji University Yongin South Korea Chonnam National University Gwangju South Korea

In Jeju Island, which is the largest island in South Korea, main portion of the required electric power is provided from the mainland through two HVDC lines. Since Jeju HVDC is operated on frequency control mode and it covers entire power variations in Jeju Island, it has a most significant impact on the power system in Jeju Island. The large-scale wind generation also could have significant impacts on the power system in Jeju Island. This is because the total capacity of wind power is considerable large compared to the load in Jeju Island and it can threaten the stable operation of the power system. In this paper, dynamic modeling of wind farms and Jeju HVDC is developed using PSS/E. Wind farms are composed of doubly fed induction generators （DFIGs）. Model writing technique is used to develop user-defined models for controlling HVDC frequency and imposing maximum penetration limit. The simulation results indicate the effectiveness of the dynamic modeling for stability studies of the power system in Jeju Island.

关键词： Doubly fed induction generator Dynamic modeling HVDC Jeju Island Model writing PSSE Wind farm

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ECNU Review of Education 2024年第1期7卷 12-41页

作者： Sang hoon Bae Kee ho choi Sungkyunkwan University Seoul National University

Purpose:In Korea,private tutoring is considered a social evil that damages the capacity of public schooling and undermines social *** the government has implemented various policies to reduce private tutoring,ranging from improving the quality of education to providing"quasi-private tutoring"programs and regulating the shadow education market,total spending on private tutoring has continued to *** study examines a little noticed but important cause of institutionalized private tutoring in ***/Approach/Methods:The study employed a socio-ecological perspective to analyze both education and socio-structural *** extensive review of the government's private tutoring reduction policies and related literature was ***:Private tutoring functions as a means by which parents can help their children compete for admission to prestigious universities and pass on wealth and social status to their *** in private tutoring has become a social norm that is taken for *** root causes of institutionalized private tutoring lie in both educational and socio-structural ***/Nalue:The study suggests that government policies,when ignoring the long-established"grammar"of parents about children's education,may either end in failure or produce unintended consequences.

关键词： Private tutoring social reproduction unintended consequences upward mobility

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国外健康建筑评价体系探索性进程评析

建筑技术 2019年第1期50卷 30-33页

作者：郑锐锋 joon-ho choi 浙江科技学院土木与建筑工程学院杭州310005 美国南加州大学建筑学院美国洛杉矶90089

介绍国外在健康建筑道路上的探索、发展历程及各自关注的重点理念,比较美国和德国的健康建筑评价体系、评价方法及特点,可供我国建立健康建筑评价体系时参考。

关键词：健康建筑健康建筑评价体系健康建筑认证