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An Experimental Study on the Behavior of Square Concrete-Filled High Strength Steel Tube Columns

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Journal of Iron and Steel Research International 2011年第S1期18卷 878-882页

作者： Hyung-suk Jung chang-sik choi Department of sustainable architectural engineering Hanyang UniversitySeoulKorea Department of architectural engineering Hanyang UniversitySeoulKorea

The paper presents an experimental study on the behavior of square concrete-filled high strength steel tube columns until *** specimens were tested to investigate the effect of high strength steel and plain strength concrete on the load carrying capacity of the square concrete-filled steel tube *** effect of the concrete which filled in the steel tube was also ***,the effect of high strength steel and the presence of concrete were also *** main parameters in the tests were:(1) the ultimate strength of steel (800 Mpa),(2) the presence of concrete in steel tube (hollow steel tube and concrete-filled steel tube),and (3) slender *** main objectives of these tests were three-step:(1) to describe a series of tests on composite columns,(2) to analyze the influence of several parameters,and (3) to compare the accuracy of the predictions by using the specifications in the code (AISC-LRFD,EC4 and AIJ etc.) for the design of high-strength composite *** results indicate that the ultimate strength of steel and presence of concrete had significant influence on both the axial compressive load capacity and the ductile of the square steel tube.

关键词： square concrete-filled steel tubes high strength steel axial compression

Microstructure of fast tool servo machining on copper alloy

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中国有色金属学会会刊：英文版 2012年第S3期22卷 820-824页

作者： Hong LU Soo-chang choi Sang-min LEE Deug-woo LEE Department of Nano Fusion Technology Pusan National University Korea Institute of Machinery & Materials Department of Nano Mechatronics Engineering Pusan National University

The development of the fast tool servo (FTS) for precision machining was *** micron machining performance of a piezoelectric-assisted FTS on copper alloy was *** results indicate that the quality of the microstructure depends mainly on two important factors:the cutting speed (or spindle speed) and the driving frequency of the *** excessive driving frequency increases the formation of *** effect of the clearance angle of the diamond tool on the microstructure machining precision was also investigated.

关键词： fast tool servo microstructure piezoelectric diamond machining copper alloy

Portable nano probe for micro/nano mechanical scratching and measuring

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Transactions of Nonferrous Metals Society of China 2011年第A01期21卷 205-209页

作者： Woo-Park JEONG chang-choi SOO Cho HYUN Woo-Lee DEUG Department of Mechanical Design Engineering Chosun University Department of Nano Fusion Technology Pusan National University Department of Nano-mechatronics Engineering Pusan National University

A nano probe system which can measure precise contact force in mN scale was demonstrated. The nano probe micro parts or optical parts in nanometer range resolution and scratch was originally designed for on-machine measuring applications and one kind of contact type measuring probes was designed for miniaturized or microfactory system. It ideally should be of small size and able to measure surface topography in nanometer scale. A commercial capacitive displacement sensor was proposed. It was a new concept in nano probe systems which can measure the displacement of shaft driven by the variation of surface topography. The nano probe mainly consisted of three parts： a capacitive displacement sensor, a porous type air slide and a contact probe part with various tip radiuses. The porous type air slide assured the shaft slided smoothly with controllable normal force in mN scale and had high positioning accuracy. The probe part which was directly in contact with target surface, can be applied to micro/nanoscale scratching as well as the measurement of sample topography by a simple tip change.

关键词： nano probe displacement sensor air slide PCD tip

Characteristics of machined surface controlled by cutting tools and conditions in machining of brittle material

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中国有色金属学会会刊：英文版 2009年第B09期19卷 194-201页

作者： Yong-Woo KIM Soo-chang choi Jeung-Woo PARK Deug-Woo LEE Department of Nano Fusion Technology Pusan National University Department of Mechanical Design Engineering Chosun University Department of Nanosystem and Nanoprocess Engineering Pusan National University

One of the ultra-precision machining methods was adapted for brittle material as well as soft material by using multi-arrayed diamond tips and high speed spindle. Conventional machining method is too hard to control surface roughness and surface texture against brittle material because the particles of grinding tools are irregular size and material can be fragile. Therefore, we were able to design tool paths and machine controlled pattern on surface by multi-arrayed diamond tips with uniform size made in MEMS fabrication and high speed spindle, and the maximum speed was about 3×105 r/min. We defined several parameters that can affect the machining surface. Those were multi-array of diamond tips (n×n), speed of air spindle and feeding rate. The surface roughness and surface texture can be controlled by those parameters for micro machining.

关键词：加工表面脆性材料条件控制刀具路径表面粗糙度特征高速主轴加工方法

EFFECT OF FABRICATION ON HIGH CYCLE FATIGUE PROPERTIES OF COPPER THIN FILMS

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Acta Mechanica Solida Sinica 2008年第4期21卷 318-326页

作者： Jun-Hyub Park Joong-Hyok An Yun-Jae Kim Hyeon-chang choi Department of Mechatronics Engineering College of EngineeringTongmyong University535Yongdang-DongNam-GuBusan608-711Korea Department of Mechanical Engineering College of EngineeringKorea UniversityAnam-dong Seongbuk-GuSeoul136-701Korea

The influence of fabrication on the tensile and fatigue behavior of copper films manufactured by 3 kinds of fabrication methods was investigated. The tensile and high cycle fatigue tests were performed using the test machine developed by authors. Young＇s moduli （72, 71 and 69 GPa, respectively） are lower than the literature values （108-145 GPa）, while the yield strengths were as high as 358, 350 and 346 MPa, respectively and the ultimate strengths as 462, 456 and 446 MPa, respectively. There is not much difference in the tensile properties of the 3 kinds of films. There is little difference in the fatigue properties of the 3 kinds of films but one of them has shorter fatigue life than others in high cycle region and longer fatigue life than others in low cycle region.

关键词： mechanical properties thin film copper high cycle fatigue test

A conformal titanyl phosphate amorphous overlayer for enhancing photoelectrochemical hydrogen peroxide production

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Journal of Energy Chemistry 2023年第11期86卷 399-408,I0009页

作者： Jaekyum Kim Young Eun Kim Minyeong Je Won Tae Hong chang-Lyoul Lee Tae-Hoon Kim Sung Min Cho chang Hyuck choi Heechae choi Woo-Seok Choe Jung Kyu Kim School of Chemical Engineering Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea SKKU Advanced Institute of Nano Technology(SAINT) Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea Theoretical Materials&Chemistry Group Institute of Inorganic ChemistryUniversity of CologneGreinstr.650939CologneGermany Advanced Photonics Research Institute(APRI) Gwangju Institute of Science and Technology(GIST)Gwangju 61005Republic of Korea Department of Materials Science and Engineering Chonnam National UniversityGwangju 61186Republic of Korea Department of Chemistry Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea Institute for Convergence Research and Education in Advanced Technology(I-CREATE) Yonsei UniversitySeoul 03722Republic of Korea Department of Chemistry Xi’an Jiaotong-Liverpool UniversitySuzhou 215123JiangsuChina

Photoelectrochemical(PEC)H_(2)O_(2)production through water oxidation reaction(WOR)is a promising strategy,however,designing highly efficient and selective photoanode materials remains challenging due to competitive reaction ***,for highly enhanced PEC H_(2)O_(2)production,we present a conformal amorphous titanyl phosphate(a-TP)overlayer on nanoparticulate TiO_(2)surfaces,achieved via lysozyme-molded in-situ surface *** a-TP overlayer modulates surface adsorption energies for reaction intermediates,favoring WOR for H_(2)O_(2)production over the competing O_(2)evolution *** density functional theory calculations reveal that a-TP/TiO_(2)exhibits a substantial energy uphill for the O·*formation pathway,which disfavors O_(2)evolution but promotes H_(2)O_(2)***,the a-TP overlayer strengthens the built-in electric field,resulting in favorable ***,a-TP/TiO_(2)exhibits 3.7-fold higher Faraday efficiency(FE)of 63%at 1.76 V *** hydrogen electrode(RHE)under 1 sun illumination,compared to bare TiO_(2)(17%),representing the highest FE among TiO_(2)-based WOR H_(2)O_(2)production *** the a-TP overlayer constitutes a promising strategy for controlling reaction pathways and achieving efficient solar-to-chemical energy conversion.

关键词： Solar H_(2)O_(2) production In-situ surface reforming Titanyl phosphate Amorphous overlayer Reaction pathway control

Accelerating temporal action proposal generation via high performance computing

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Frontiers of Computer Science 2022年第4期16卷 59-68页

作者： Tian Wang Shiye Lei Youyou Jiang choi chang Hichem Snoussi Guangcun Shan Yao Fu Institute of Artificial Intelligence Beihang UniversityBeijing100191China School of Automation Science and Electrical Engineering Beihang UniversityBeijing100191China School of Software Tsinghua UniversityBeijing100084China Department of Computer Engineering Gachon UniversitySeongnam13120South Korea Institute Charles Delaunay-LM2S FRE CNRS 2019 University of Technology of TroyesTroyes10010France School of Instrumentation Science and Opto-electronics Engineering Beihang UniversityBeijing100191China changchun Institute of Optics Fine Mechanics and PhysicsChinese Academy of SciencesChangchun130033China

Temporal action proposal generation aims to output the starting and ending times of each potential action for long videos and often suffers from high computation *** address the issue,we propose a new temporal convolution network called Multipath Temporal ConvNet(MTCN).In our work,one novel high performance ring parallel architecture based is further introduced into temporal action proposal generation in order to respond to the requirements of large memory occupation and a large number of ***,the total data transmission is reduced by adding a connection between multiple-computing load in the newly developed *** to the traditional Parameter Server architecture,our parallel architecture has higher efficiency on temporal action detection tasks with multiple *** conduct experiments on ActivityNet-1.3 and THUMOS14,where our method outperforms-other state-of-art temporal action detection methods with high recall and high temporal *** addition,a time metric is further proposed here to evaluate the speed performancein the distributed training process.

关键词： temporal convolution temporal action proposal generation deep learning

Sexual dimorphism and sex-differential migration of Little Buntings(Emberiza pusilla)at an East Asian stopover site

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Avian Research 2022年第1期13卷 87-93页

作者： Sook-Young Cho Hyun-Young Nam Se-Young Park chang-Yong choi Bird Research Center Korea National Park Research InstituteJeonnam58863Republic of Korea Division of Zoology Honam National Institute of Biological ResourcesMokpo58762Republic of Korea School of Biological Sciences College of Natural SciencesSeoul National UniversitySeoul08826Republic of Korea Department of Agriculture Forestry and BioresourcesCollege of Agriculture and Life SciencesSeoul National UniversitySeoul08826Republic of Korea

Sex differences in morphology provide key information for understanding a species'morphological adaptations in relation to the evolution of sexual *** migratory birds,morphological traits have adapted to long-distance travel,and sexual dimorphism is typically related to sex-differential migration *** Buntings(Emberiza pusilla)have one of the longest migrations and are the least dichromatic species among the Emberiza *** this study,we measured sexual size dimorphism and sexual dichromatism of Little Buntings in relation to the spring arrival dates at a stopover site in *** length was the most important predictor for identifying sex;the wings of males were longer than those of *** also had a significantly stronger chestnut color of the head feathers than females,but this color difference was more prominent in the spring than in the *** arrived earlier than females by four *** dates correlated with both size and color,but unlike other bunting species previously studied in the same area,there was no clear sex-differential trend in the relationship between arrival date and morphological *** differences in the degree of sexual dichromatism suggest that chestnut plumage coloration can be used as a social or sexual signal of males in the breeding *** correlation of size and color to early arrival regardless of sex may indicate that a preference for assortative mating exists or that a sex-differential migration strategy is not clearly defined in the early stages of northward *** findings on the sexual dimorphism of Little Buntings provide insight into the evolution of the sex-differential migration of buntings in the East Asian Flyway.

关键词： Digital photography Emberiza pusilla Little Bunting Protandrous migration Sexual dichromatism Sexual dimorphism

Nanocrystalline Iron Pyrophosphate-Regulated Amorphous Phosphate Overlayer for Enhancing Solar Water Oxidation

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Nano-Micro Letters 2022年第12期14卷 387-400页

作者： Chengkai Xia Yuankai Li Minyeong Je Jaekyum Kim Sung Min Cho chang Hyuck choi Heechae choi Tae-Hoon Kim Jung Kyu Kim School of Chemical Engineering Sungkyunkwan University(SKKU)2066 Seobu-roJangan-guSuwon 16419Republic of Korea Theoretical Materials and Chemistry Group Institute of Inorganic ChemistryUniversity of CologneGreinstr.650939 CologneGermany Department of Chemistry Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea Department of Materials Science and Engineering Engineering Research CenterChonnam National UniversityGwangju 61186Republic of Korea

A rational regulation of the solar water splitting reaction pathway by adjusting the surface composition and phase structure of catalysts is a substantial approach to ameliorate the sluggish reaction kinetics and improve the energy conversion *** this study,we demonstrate a nanocrystalline iron pyrophosphate(Fe_(4)(P_(2)O_(7))_(3),FePy)-regulated hybrid overlayer with amorphous iron phosphate(FePO_(4),FePi)on the surface of metal oxide nanostructure with boosted photoelectrochemical(PEC)water *** manipulating the facile electrochemical surface treatment followed by the phosphating process,nanocrystalline FePy is localized in the FePi amorphous overlayer to form a heterogeneous hybrid *** FePy-regulated hybrid overlayer(FePy@FePi)results in significantly enhanced PEC performance with long-term *** with the homogeneous FePi amorphous overlayer,FePy@FePi can improve the charge transfer efficiency more significantly,from 60% of FePi to 79%of FePy@*** density-functional theory calculations reveal that the coexistence of FePi and FePy phases on the surface of metal oxide results in much better oxygen evolution reaction kinetics,where the FePi was found to have a typical down-hill reaction for the conversion from OH*to O_(2),while FePy has a low free energy for the formation of OH*.

关键词： Water oxidation Photoelectrochemical cell Metal pyrophosphate Electrochemical surface treatment