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Synthesis of tin nanoparticles through modified polyol process and effects of centrifuging and drying on nanoparticles

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中国有色金属学会会刊：英文版 2012年第S3期22卷 707-711页

作者： Sang-Soo CHEE jong-Hyun lee Department of Materials Science and Engineering Seoul National University of Science and Technology

Sn nanoparticles with average diameter of 13.1 nm were synthesized by modified polyol process,and their melting point was observed to be about 40 °C less than that of bulk *** though Sn nanoparticles are solid and covered with thin PVP capping and oxide layer,Sn nanoparticles in solution agglomerate upon centrifugation,resulting in a melting point *** to stickiness of the PVP capping layer,extensive aggregation between Sn nanoparticles was observed after ***,the aggregation behavior did not further influence the melting point,because actual agglomeration did not occur in the aggregates.

关键词： tin nanoparticle melting point centrifugation agglomeration aggregation

Nielsen coincidence theory on infra-solvmanifolds of Sol

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Science China Mathematics 2021年第8期64卷 1861-1884页

作者： jong Bum lee Karen Regina Panzarin Department of Mathematics Sogang UniversitySeoul 121-742Korea Departamento de Matematica Universidade Federal de Sao CarlosSao CarlosSP 13565-905Brazil

We derive averaging formulas for the Lefschetz coincidence numbers,the Nielsen coincidence numbers and the Reidemeister coincidence numbers of maps on infra-solvmanifolds modeled on a connected and simply connected solvable Lie group of type(R).As an application,we compare our formula for the Nielsen coincidence numbers with a result of Jezierski(1992)for pairs of maps on some infra-solvmanifolds of *** all the pairs of self-maps of a nonorientable infra-solvmanifold of Sol,we determine the sets of all the possible values of the Nielsen coincidence numbers and the Reidemeister coincidence numbers.

关键词： averaging formula infra-solvmanifold Lefschetz coincidence number Nielsen coincidence number Reidemeister coincidence number Sol-geometry

Assessment criteria for nonverbal interaction contents in r-learning

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Journal of Central South University 2013年第9期20卷 2388-2398页

作者： CHOI jong-hong lee jong-yun YOON Heung-seob Department of Computer Education Chungbuk National University Department of English Education Chungbuk National University

r-learning,which is based on e-learning and u-learning,is defined as a learning support system that intelligent robots serve verbal and nonverbal interactions on ubiquitous computing *** order to guarantee the advantages of r-learning contents with no limits of timc and place and with nonverbal interaction which are not in e-learning contents,in recent years,assessment criteria for r-learning contents are urgently ***,the reliable and valid assessment criteria were developed for nonverbal interaction contents in r-learning,and its detailed research content is as ***,assessment criteria for nonverbal interaction in r-learning contents will be specified into gesture,facial expression,semi-verbal message,distance,physical contact and ***,the validity of the developed assessment criteria will be proved by ***,the assessment criteria for nonverbal interaction contents will be helpful when choosing the better r-learning content and producing the better r-learning content,and the reliability of school education is improved ultimately.

关键词： r-learning, r-learning contents assessment criteria nonverbal interaction contents confirmatory factor analysis construct validity

Effect of Fe_2P in LiFePO_4/Fe_2P composite on electrochemical properties synthesized by MA and control of heat condition

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Rare Metals 2006年第Z2期25卷 179-183页

作者： PARK jong Suk lee Kyung Tae lee Kyung Sub Department of Material Science and Engineering Hanyang University Seoul 133-731 Korea

In order to control the size and distribution of the high conductive Fe2P in LiFePO4/Fe2P composite, two different cooling rates (Fast: 15 ℃·min-1, Slow: 2 ℃·min-1) were employed after mechanical alloying. The discharge capacity of the fast cooled was 83 mAh·g-1 and the slow cooled 121 mAh·g-1. The particle size of the synthesized powder was examined by transmission electron microscopy and distribution of Fe2P was characterized using scanning electron microscopy (SEM). In addition, two-step heat treatment was carried out for better distribution of Fe2P. X-ray diffraction (XRD) and Rietveld refinement reveal that LiFePO4/Fe2P composite consists of 95.77% LiFePO4 and 4.33% of Fe2P.

关键词： LiFePO4/Fe2P composite mechanical alloying heat treatment discharge capacity

Response of phenology- and yield-related traits of maize to elevated temperature in a temperate region

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The Crop Journal 2017年第4期5卷 305-316页

作者： Dana Shim Kyu-jong lee Byun-Woo lee Department of Plant Science Seoul National University Seoul 151-921 Republic of Korea Research Institute for Agriculture and Life Sciences Seoul National University Seoul 151-921 Republic of Korea

Extreme high temperatures detrimental to maize production are projected to occur more frequently with future climate *** and yield-related traits were investigated under several levels of elevated temperature in two early-maturing hybrid cultivars:Junda 6(grown in northeastern China)and Chalok 1(grown in South Korea).They were cultivated in plastic houses in Suwon,Korea(37.27°N,126.99°E)held at target temperatures of ambient(AT),AT+1.5°C,AT+3°C,and AT+5°C at one sowing date in 2013 and three different sowing dates in *** and reproductive growth durations showed variation depending on sowing date,experimental year,and *** duration tended to decrease,but not necessarily,with temperature elevation,but somewhat increased again above a certain *** temperature-dependent variation was greater during grain filling than in the vegetative period before *** temperature showed no significant effects on duration or peak dates of silking and anthesis,and thus on anthesis–silking *** yield tended to decrease with temperature elevation above ambient,showing a sharper linear decrease with mean growing season temperature increase in Junda 6 than in Chalok *** decrease in kernel number accounted for a much greater contribution to the yield reductions due to temperature elevation than did the decrease in individual kernel weight in both *** harvestable kernel weight was not significantly affected by temperature elevation *** number showed a linear decrease with mean growth temperature from early ear formation to early grain-filling stage,with Junda 6 showing a much severer decrease than Chalok *** number reduction due to temperature elevation was attributable more to the decrease in differentiated ovule number than to the decrease in kernel set in Chalok 1,but largely to the decrease of kernel set in Junda 6.

关键词： Maize Elevated temperature Phenology Yield Yield-related traits

ENERGY ABSORPTION CONTROL CHARACTERISTICS OF AL THIN-WALLED TUBES UNDER IMPACT LOAD

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Acta Mechanica Solida Sinica 2008年第4期21卷 383-388页

作者： kil-Stmg lee Yong-Jun Yang Sun-Kyu Kim In-Young Yang Department of Mechanical Design Engineering Chostrn University 375 Seosuk-dong Dong-gu Gwangju 501-759 Korea Department of Advanced Parts and Materials Engineering Graduate School Chosun University 375 Seosuk-dong Dong-gu Gwangju 501-759 Korea Department of Automobile Engineering Iksan National College 194-5 Ma-dong Iksan Chonbuk 570-752 Korea

An experimental investigation was carried out to study the energy absorption characteristics of thin-walled square tubes subjected to dynamic crushing by impact loading to develop the optimum structural members. Here, the controller is introduced to improve and control the absorbed energy of thin-walled square tubes in this paper. When the controller were used, the experimental results of crushing of square tubes controlled by the controller＇s elements showed a good candidate for a controllable energy absorption capability in impact crushing.

关键词： impact load Al thin-walled tubes energy absorption controller

Preparation of TiAlN/ZrN and TiCrN/ZrN multilayers by RF magnetron sputtering

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中国有色金属学会会刊：英文版 2009年第4期19卷 795-799页

作者： jong-Kook lee G won-Seung YANG Department of Advanced Materials Engineering Chosun University BK21 Education Center of Mould Technology for Advanced Materials and Parts Chosun University

Titanium-based nitride coatings on cutting tools,press molds and dies can be used to prolong their life cycle because of their superior corrosion and oxidation ***/ZrN and TiCrN/ZrN multilayer coatings were prepared by RF magnetron sputtering,and their microstructural evolution and corrosion resistance during heat treatment were *** TiAlN/ZrN and TiCrN/ZrN multilayer coatings are degraded by heating up to 600 ℃ with the formation of oxides particles on the *** the heat treatment,the TiCrN/ZrN and TiAlN/ZrN multilayer coatings show the lowest corrosion current density and the highest polarization resistance at temperature range of 400-500 ℃.Consequently,the TiAlN/ZrN and TiCrN/ZrN multilayer coatings show good corrosion resistance at temperature range of 400-500 ℃ during heating.

关键词：射频磁控溅射溅射制备氮化锆多层膜钛铝耐腐蚀性腐蚀电流密度

The use of artificial nest boxes by Siberian flying squirrels (Pteromys volans) in South Korea

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Journal of Forestry Research 2019年第3期30卷 1131-1137页

作者： jong-U Kim Woo-shin lee Eun-Jae lee Department of Forest Sciences Seoul National University Seoul 08826Republic of Korea Urban Planning Research Division Daejeon Sejong Research InstituteDaejeon 34863Republic of Korea

In this study, we examined the use of artificial nest boxes by Siberian flying squirrels (Pteromys volans) in three coniferous and mixed forests in Gangwon Province, South Korea. Six hundred and twelve boxes with different sized entry holes (ranging from 3 to 7 cm in diameter) were placed in the forests between 2004 and 2009. Pteromys volans used nine boxes in the coniferous forests and two boxes in the mixed forests. The squirrels only used boxes with entrance holes measuring 3.5, 4, and 5 cm in diameter, showing a strong and moderate preference for boxes with 5 and 4-cm holes, respectively, and a strong avoidance for boxes with 3- and 7-cm holes. Therefore, we suggest placing artificial nest boxes with entrance holes 5 cm in diameter to encourage breeding activity. Most nests made in the artificial boxes were composed of fibrous materials from woody vines. We recommend placing artificial nest boxes with holes of 5-cm diameter in coniferous forests, which support dense populations of P. volans, to survey whether this approach would positively affect the breeding habits and population maintenance of this species.

关键词： Artificial nest box Coniferous forests Nest materials Siberian flying squirrel Woody vines

Porously Reduced 2-Dimensional Bi_(2)O_(2)CO_(3) Petals for Strain-Mediated Electrochemical CO_(2) Reduction to HCOOH

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Energy & Environmental Materials 2024年第1期7卷 215-221页

作者： Won Seok Cho Dae Myung Hong Wan Jae Dong Tae Hyung lee Chul jong Yoo Donghwa lee Ho Won Jang jong-Lam lee Department of Materials Science and Engineering Pohang University of Science and Technology(POSTECH)Pohang Gyungbuk 37673Korea Department of Materials Science and Engineering Research Institute of Advanced Materials Seoul National UniversitySeoul 08826Korea

Here we introduce bismuth-based catalysts for the efficient electrochemical reduction of CO_(2)to formic acid(HCOOH),which are composed of petal-shaped Bi_(2)O_(2)CO_(3)(BOC)that spontaneously formed from Bi thin film in aqueous carbonate solution at room *** the electrochemical reduction process,the BOC petals transform to reduced BOC(R-BOC)consisting of individual BOC and Bi *** mismatch between both domains induces biaxial strain at the *** functional theory calculations suggest that the tensile strain on the Bi domain stabilizes the*OCHO intermediate,reducing the thermodynamic barrier toward CO_(2)conversion to *** with the thermodynamic benefit and the unique nanoporous petal-shaped morphology,R-BOC petals have a superior Faradaic efficiency of 95.9%at-0.8 V_(RHE)for the electrochemical conversion of CO_(2)to *** work demonstrates that the spontaneously formed binary phases with desirable lattice strain can increase the activity of bismuth catalysts to the CO_(2)reduction reaction;such a strategy can be applicable in design of various electrocatalysts.

关键词： bismuth carbon dioxide reduction formic acid heterointerfaces strain