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高频软开关谐振整流器及受控系统特性

大功率变流技术 1997年第5期 1-13页

作者： h.c.choi 刘连根韩

提出一种可获得正弦形交流电网电流、应用串联型谐振电路的高频软开关交/直整流器。采用这种整流器,交流电网功率因数高且谐波电流小。除此之外,它还有诸如功率密度高和输出电压范围宽等一些优点。输出电压由数字比例积分(PI)控制器调节... 详细信息

提出一种可获得正弦形交流电网电流、应用串联型谐振电路的高频软开关交/直整流器。采用这种整流器,交流电网功率因数高且谐波电流小。除此之外,它还有诸如功率密度高和输出电压范围宽等一些优点。输出电压由数字比例积分(PI)控制器调节,采样时间对应于交流网压过零点。为检查其稳定性和动态特性,推导包括此控制器在内的闭环系统模型。通过极点配置技术决定PI控制器的增益且由根轨迹图考察闭环系统的动态性能。仿真和试验结果非常吻合。

关键词：高频软开关整流器原理特性数学模型仿真实验结论

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共面转换型42英寸液晶电视的发展

现代显示 2004年第4期 7-10页

作者： I.J.chung c.h.Oh h.c.choi 孙玉宝 LG.菲力浦液晶显示器公司研发中心河北工业大学应用物理系

我们通过使用超级共面转换(SuperIn-Plane-Switching)模式和过驱动(Over-Driving)电路技术,开发出具有宽视角和快速响应的42英寸(1280×768,159)大尺寸液晶电视(LcD-TV)。通过使用膜超级共面转换技术获得了在任意方向的宽视角,通过优化... 详细信息

我们通过使用超级共面转换(SuperIn-Plane-Switching)模式和过驱动(Over-Driving)电路技术,开发出具有宽视角和快速响应的42英寸(1280×768,159)大尺寸液晶电视(LcD-TV)。通过使用膜超级共面转换技术获得了在任意方向的宽视角,通过优化液晶材料和液晶盒的设计,获得了更快的响应时间(12ms)。

关键词：液晶电视超级共面转换模式平板电视

Mathematical modeling and simulations of stress mitigation by coating polycrystalline particles in lithium-ion batteries

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Applied Mathematics and Mechanics(English Edition) 2024年第6期45卷 947-962页

作者： N.IQBAL J.choi S.F.ShAh c.LEE S.LEE Department of Mechanical Roboticsand Energy EngineeringDongguk University-SeoulSeoul 04620Republic of Korea

A chemo-mechanical model is developed to investigate the effects on the stress development of the coating of polycrystalline Ni-rich LiNixMnyco_(z)O_(2)(x≥0.8)(NMc)particles with poly(3,4-ethylenedioxythiophene)(PEDOT).The simulation results show that the coating of primary NMc particles significantly reduces the stress generation by efficiently accommodating the volume change associated with the lithium diffusion,and the coating layer plays roles both as a cushion against the volume change and a channel for the lithium transport,promoting the lithium distribution across the secondary particles more ***,the lower stiffness,higher ionic conductivity,and larger thickness of the coating layer improve the stress *** paper provides a mathematical framework for calculating the chemo-mechanical responses of anisotropic electrode materials and fundamental insights into how the coating of NMc active particles mitigates stress levels.

关键词： lithium-ion battery(LIB) polycrystalline particle coating finite element simulation Ni-rich LiNixMnyco_(z)O_(2)(x>0.8)(NMc)

Anti-obesity effects of fucoidan from Sargassum thunbergii in adipocytes and high fat diet induced obese mice through inhibiting adipogenic specific transcription factor

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Food Science and human Wellness 2024年第3期13卷 1608-1616页

作者： hyo-Geun Lee h.h.A.c.K.Jayawardhana Fengqi Yang D.P.Nagahawaththa N.M.Liyanage Kyung-Mo Song Yun-Sang choi Seung-hong Lee You-Jin Jeon Min-cheol Kang Department of Marine Life Sciences Jeju National UniversityJeju 63243Republic of Korea Marine Science Institute Jeju National UniversityJeju 63333Republic of Korea Research Group of Food Processing Korea Food Research InstituteWanju 55365Republic of Korea Department of Pharmoceutical Engineering Soonchunhyang UniversityAsan 31538Republic of Korea

The prevalence of obesity has increased and is a health concern *** to the concerns regarding synthetic anti-obesity treatments,nowadays natural products become a *** studies proved that there is a potential to use marine algae as anti-obesity ***,in this study,the lipid inhibitory effect of crude polysaccharide of amyloglucosidase-assisted hydrolysate from Sargassum thunbergii(STAc)and its fucoidan fractions(STAFs)on 3T3-L1 cells and high-fat diet(hFD)-induced obese mice were *** to the results,the STAF3,showed the highest xylose content and exhibited significant inhibitory effects on lipid accumulation by downregulating adipogenic and lipogenic proteins in 3T3-L1 ***,oral supplementation with STAc significantly declined gain in body weight and fat weight,and serum lipid contents in an hFD-induced obesity mouse *** and chemical characterizations demonstrated that puritied STAF3 has consistent surface morphology and small particle size,with similar structural characteristics as commercial ***,these results indicate that STAc and purified STAF3 from Sargassum thunbergia is a potent source to develop as ananti-obesity agents or functional food products to counter obesity.

关键词： Sargassum thunbergii Fucoidan Anti-obesity Anti-steatosis

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

Synthetic brochosomes:Design,synthesis,and applications

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Nano Research 2024年第2期17卷 734-742页

作者： Lin Wang Jinsol choi Tak-Sing Wong Department of Mechanical Engineering The Pennsylvania State UniversityUniversity ParkPA 16802USA Materials Research Institute The Pennsylvania State UniversityUniversity ParkPA 16802USA Department of Biomedical Engineering The Pennsylvania State UniversityUniversity ParkPA 16802USA

Brochosomes,which are nanoscopic buckyball-shaped granules produced by leafhoppers,are one of the most intricate structures discovered in *** functions of brochosomes have been proposed but only a few have been experimentally validated due to the challenge of fabricating their synthetic *** in micro-and nanofabrication have recently led to the emergence of synthetic brochosomes,opening up new possibilities for innovative *** review explores the early discovery of natural brochosomes and their geometrical features,followed by the recent progress in fabricating synthetic brochosomes and their *** on future applications and challenges in the scalable manufacturing of synthetic brochosomes are discussed.

关键词： synthetic brochosomes leafhopper antireflection superhydrophobicity surface-enhanced Raman scattering photocatalyst energy harvesting

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 cF cF. To elucidate the close relationship between hydration properties and electrochemical performances in LnBScF cathodes, 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

钆塞酸二钠增强MRI T2 mapping成像：预测肝硬化病人失代偿和死亡

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国际医学放射学杂志 2022年第1期 118-118页

作者： W.Yang J.E.Kim h.c.choi M.J.Park h.Y.choi h.S.Shin 谢双双

摘要目的肝脏MRI T2mapping能否预测肝硬化病人的失代偿与死亡。方法回顾性纳入292例进行钆塞酸二钠增强MRI检查的肝硬化病人，在注射对比剂后10 min的肝

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Analysis and Modeling of Mobile Phone Activity Data Using Interactive cyber-Physical Social System

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computers, Materials & continua 2024年第9期80卷 3507-3521页

作者： Farhan Amin Gyu Sang choi School of computer Science and Engineering Yeungnam UniversityGyeongsan38541Republic of Korea

Mobile networks possess significant information and thus are considered a gold mine for the researcher’s *** call detail records(cDR)of a mobile network are used to identify the network’s efficacy and the mobile user’s *** is evident from the recent literature that cyber-physical systems(cPS)were used in the analytics and modeling of telecom *** addition,cPS is used to provide valuable services in smart *** general,a typical telecom company hasmillions of subscribers and thus generatesmassive amounts of *** this aspect,data storage,analysis,and processing are the key *** solve these issues,herein we propose a multilevel cyber-physical social system(cPSS)for the analysis and modeling of large internet *** proposed multilevel system has three levels and each level has a specific ***,raw call Detail Data(cDR)was collected at the first ***,the data preprocessing,cleaning,and error removal operations were *** the second level,data processing,cleaning,reduction,integration,processing,and storage were ***,suggested internet activity record measures were *** proposed system initially constructs a graph and then performs network *** proposed cPSS system accurately identifies different areas of internet peak usage in a city(Milan city).Our research is helpful for the network operators to plan effective network configuration,management,and optimization of resources.

关键词： cyber-physical social systems big data cyber-physical systems pervasive computing smart city big data management techniques