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Influence of Ti^(4+) doping on hyperfine field parameters of Mg_(0.95)Mn_(0.05)Fe_(2-2x)Ti_(2x)O_4(0≤x≤0.7)

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Journal of Central South University 2010年第6期17卷 1139-1143页

作者： kUMAR S PRAkASh R ALIMUDDIN choi h k kOO B h SONG J I ChUNG h JEONG h LEE C G School of Nano and Advanced Materials Engineering Changwon National UniversityChangwon 641773Korea Department of Mechanical Engineering Changwon National UniversityChangwon 641773Korea Department of Applied Physics Aligarh Muslim UniversityAligarh 202002India Department of Precision & Mechanical Engineering and Bk21 Eco-Friendly heat & Cooling Energy Mechanical Research Team Gyeongsang National U niversityTongyeong 650160Korea

The mixed spinel ferrite system Mg0.95Mn0.05Fe2-2xTizxO4 （0 ≤x ≤ 0.7） was synthesized by the conventional solid-state reaction technique. The effect of Ti^4＋ doping was studied by using the Moessbauer spectroscopy measurements at room temperature. From the analysis of the Moessbauer spectra, it is observed that s-electron density, electric field gradient （EFG）, quadrupole coupling constant （QCC） and the net hyperfine magnetic fields acting on the Moessbauer nuclei-FeA^3＋ and FeB^3＋ change with the increase of Ti^4＋ doping in Mg0.95Mn0.05Fe2O4. The hyperfine magnetic field decreases with the increase of Ti^4＋ doping.

关键词： spinel ferrite Moessbauer spectroscopy hyperfine magnetic field isomer shift Ti^4+ doping

Characterization of response behaviors of chironomid larvae in different concentrations of toxic chemicals

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Characterization of response behaviors of chironomid larvae ...

Numerical modelling of a low power non-transferred arc plasma reactor for methane conversion

第三世界生态高峰会

作者： choi k.h. Lec S.h. Park Y.S. Chon T.-S. Division of Biological Sciences.Pusan National University.Busan(Pusan)609-735.Republic of korea Depatrtment of Physics Pusan National University Busan(Pusan)609-735. Republic of korea Department of Biology kyung hee University.hoegi-dong Dongdaemum-gu.seou 130-701 Republic of korea.

Although behavioral data are useful for detecting presence of toxic chemicals in environment,the data are usually complex and are difficult to *** the use of artificial neural networks has been reported to be useful for detecting toxic chemicals through pattern recognition of the movement *** this study,we demonstrated that computational methods based on the Self-Organizing Map could be used for characterizing response behaviors of indicator specimens at different levels of toxic *** 2-D movement tracks of chironmid(Chironomus riparius)larvae were continuously recorded before and after the treatments of Diazinon at the concentrations of 0.001 mg/L and 0.01 mg/*** parametcrs such as speed,acceleration, stop number,***,locomotory rate and meander were selected and were used as input data for training with the Self-Organizing Map (SOM).The movement tracks were accordingly grouped according to different levels of the *** results suggested that patterning by SOM could be useful for detecting different levels of toxic chemicals in semi-natural conditions.

关键词： Characterization of response behaviors of chironomid larvae in different concentrations of toxic chemicals

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Plasma Science and Technology 2019年第6期21卷 29-37页

作者： B I MIN D k DINh D h LEE T h kIM S choi Institute for Nuclear Science and Technology Jeju National University 102 Jejudaehak-ro Jeju 63243Republic of Korea University of Science and Technology(UST) 217 Gajeong-ro Yuseong-gu Daejeon 34113 Republic of Korea korea Institute of Machinery and Materials 156 Gajeongbuk-ro Yuseong-gu Daejeon 34103 Republic of Korea Department of Nuclear and Energy Engineering Jeju National University 102 Jejudaehak-ro Jeju 63243Republic of Korea

Thermal flow characteristics and the methane conversion reaction in a low power arc plasma reactor for efficient storage and transport of methane,which is the main component of shale gas,were *** temperature and velocity distributions were calculated according to the type of discharge gases and arc current level by a self-developed magnetohydrodynamics (MhD)code and a commercial ANSYS-FLUENT code;the transport of chemical species was analyzed as including the chemical reactions of methane *** simulated results were verified by the comparison of calculated and measured arc voltages with permissible low error as under 4%.Three C2 hydrocarbon gases with ethane (C2h6),ethylene (C2h4),and acetylene (C2h2)were selected as the converted species of methane from experimental *** mass fraction of C2 hydrocarbons and hydrogen as the product of the conversion reaction at the reactor was also *** values show good agreement with the actual experimental results in that the major conversion reaction occurred in C2h2 and hydrogen,and the conversions to C2h6,C2h4,and hydrogen were minor reactions of methane pyrolysis conversion.

关键词： numerical modelling non-transferred arc plasma methane chemical reaction

Relation between etching profile and voltage-current shape of sintered SiC etching by atmospheric pressure plasma

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Plasma Science and Technology 2019年第4期21卷 137-144页

作者： D C SEOk S R YOO k I LEE Y S choi Y h JUNG Plasma Technology Research Center National Fusion Research InstituteGunsan City 54004Republic of Korea

Sintered silicon carbide(SiC)was etched by a dielectric barrier discharge source.A high voltage bipolar pulse was used with helium gas for the plasma *** stable filament plasma was generated and could be used for SiC *** the processing gas(NF3)mixing rate increased,the width and depth of the etching profile became narrower and *** differentiated V-Q Lissajous method was used for measuring the capacitances(Ceq)of the electrode after the plasma turned *** width of the etching profile was proportional to *** the current peak value/smx of the substrate current in creased,the volume removal rate of SiC *** etch depth was proportional to the ratio of/smx to ***,because of the different characteristics of the plasma disks on SiC substrate by the voltage polarity,the etching profile was ***,in high NF3 mixing process,the etching profile became stable and deeper.

关键词： dielectric barrier discharge silicon carbide plasma etching、filament discharge,surface charge

Numerical analysis of thermal plasma scrubber for CF4 decomposition

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Plasma Science and Technology 2019年第6期21卷 9-14页

作者： J kO T h kIM S choi Department of Nuclear and Energy Engineering Jeju National University Jeju 63243 Republic of Korea Institute for Nuclear Science and Technology Jeju National University Jeju 63243 Republic of Korea

CF4 gas emitted in the semiconductor and display manufacturing process is a very harmful greenhouse *** must be removed or converted safely due to its extreme *** a CF4 decomposition system using a thermal plasma scrubber was commercialized,its removal efficiency is *** this work,a numerical analysis of CF4 decomposition in the thermal plasma scrubber was carried out in order to propose an efficient decomposition *** decomposition and recombination temperatures of CF4 were analyzed using thermodynamic equilibrium *** chemical reaction of CF4 decomposition into carbon and fluorine gas was considered in this numerical *** injection position and angle of the CF4 were controlled in order to enhance the decomposition *** vertical injection of CF4 near the torch exit improved the mixing of the CF4 with the thermal plasma *** addition,it was confirmed that the high temperature region expanded due to a vortex generated by strong turbulence in the bottleneck-shaped *** a result,it is revealed that the CF4 injection location and the reactor configuration are the most important factors in improving the decomposition rate.

关键词： numerical simulation decomposition CF4 thermal plasma scrubber

A comprehensive study on butanolysis of furfuryl alcohol to butyl levulinate using tungstated zirconia and sulfonated carbon catalysts

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Carbon Resources Conversion 2021年第1期4卷 111-121页

作者： Upender Rao Thuppati C.choi h.Machida k.Norinaga Department of Chemical Systems Engineering Graduate School of EngineeringNagoya UniversityAichi 464-8603Japan

This work presents the formation of butyl levulinate,a potential fuel additive,and an excellent renewable chemical obtained by the butanolysis of furfuryl alcohol(FAL)over a solid acid *** butanolysis of furfuryl alcohol reaction is a strong function of acidity for which tungstated zirconia(WO_(3)-ZrO_(2)),a robust solid acid catalyst,and a sulfonated carbon catalyst were employed to produce high yields of butyl levulinate targeting a lower initial molar ratio of butanol to FAL.A maximum of 28 mol%yield of butyl levulinate was obtained with tungstated zirconia *** prepared sulfonated carbon catalyst at high reaction temperatures facilitated the complete conversion of reaction intermediate,2-butoxymethylfuran(2-BMF)through which butyl levulinate was formed,and as high as 80 mol%of butyl levulinate yield was produced at an initial mole ratio of 8.5:1 of butanol to *** better results of sulfonated carbon catalyst could be attributed to the presence of-SO3h,carboxylic acid,and phenolic Oh groups on the carbon surface.

关键词： Butanolysis Tungstated zirconia Sulfonated carbon And butyl levulinate

Study on Ship Automatic Berthing System with Mooring Lines

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China Ocean Engineering 2017年第1期31卷 19-29页

作者： k.U.Yang J.G.hur M.S.choi D.J.Yeo J.h.Byun Department of Power System Engineering Chonnam National UniversityYeosu 550-749Korea College of Fisheries and Ocean Science Chonnam National UniversityYeosu 550-749Korea Departrnent of Maritime Police Science Chonnam National UniversityYeosu 550-749Korea

This study describes an automatic berthing system with mooring lines. It is designed to be berthed by using mooring device on the upper deck of a ship. It is to berth once maintaining parallel with the quay by controlling both forward and aft breast lines. Berthing method is used through length adjustment of mooring lines connected between ship and quay by controlling the angular velocity and the torque of hydraulic motor in mooring device. The study is conducted under three changing conditions of draft, such as even-keel, rise of the gravity center and trim to stern. Variables affecting berthing stability are determined based on the control performance of each condition. Bond graphs method is used to model the system. Controller is designed as PID control method of reference-model algorithm. The control program is composed of synchronous control system based on the equations derived with the numerical analysis. The tank test is conducted to verify the usefulness of the control program.

关键词： hydraulic maintain affecting berth torque adjustment draft attitude gravity verify

Current Status of the kSTAR Engineering

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Plasma Science and Technology 2004年第1期6卷 2159-2165页

作者： J.S.Bak k.kim C.h.choi Y.k.Oh B.C.kim N.I.her h.L.Yang G.S.Lee the kSTAR Team korea Basic Science Institute 52 Yeoeun-Dong Yusung-Ku Daejeon 305-333 KoreaKorea Basic Science Institute 52 Yeoeun-Dong Yusung-Ku Daejeon 305-333 KoreaKorea Basic Science Institute 52 Yeoeun-Dong Yusung-Ku Daejeon 305-333 KoreaKorea Basic Science Institute 52 Yeoeun-Dong Yusung-Ku Daejeon 305-333 KoreaKorea Basic Science Institute 52 Yeoeun-Dong Yusung-Ku Daejeon 305-333 KoreaKorea Basic Science Institute 52 Yeoeun-Dong Yusung-Ku Daejeon 305-333 KoreaKorea Basic Science Institute 52 Yeoeun-Dong Yusung-Ku Daejeon 305-333 KoreaKorea Basic Science Institute 52 Yeoeun-Dong Yusung-Ku Daejeon 305-333 KoreaKorea Basic Science Institute 52 Yeoeun-Dong Yusung-Ku Daejeon 305-333 Korea

As there is substantial progress in the kSTAR tokamak engineering, all themajor structures and sub-systems are under fabrication and in procurement phase. The vacuum vessel,port, cryostat cylinder, lid, and bellows are being rigorously fabricated in the factory. The lowerpart of the kSTAR such as cryostat base and gravity support has been almost finished in itsfabrication. There are also great progresses and significant results in manufacturing of thesuperconducting magnet, including four Toroidal Field (TF) coils, lower and upper PF7 coils whichare the largest Poloidal Field (PF) coils. The TFOO coil, which has been made for test and back-upof the TF magnet system, was successfully tested in the cool-down and current charging. As thefabrications and procurements of major structures have been actively proceeded, assembly works werealso launched from Aug. 2003. More detailed description on these status, results, and plans will bedescribed in this paper.

关键词： kSTAR tokamak vacuum vessel magnet cryostat tokamak assembly

Empirical Evidence for the Look-Ahead Behavior of Pedestrians in Bi-directional Flows

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Chinese Physics Letters 2012年第6期29卷 299-302页

作者： GUO Ren-Yong WONG SC XIA Yin-hua hUANG hai-Jun LAM William h.k. choi keechoo College of Computer Science Inner Mongolia UniversityHohhot 010021 Department of Civil Engineering The University of Hong KongPokfulam RoadHong Kong Department of Mathematics University of Science and Technology of ChinaHefei 230026 School of Economics and Management Beijing University of Aeronautics and AstronauticsBeijing 100191 Department of Civil and Structural Engineering The Hong Kong Polytechnic UniversityHong Kong Department of Transportation Engineering Ajou UniversitySan 5 Woncheon-DongYeongtong-KuSuwon442-749 Korea

Using the sample data obtained from a group of pedestrian experiments,a function formulating the velocitydensity relationship of pedestrians and linear regression is proposed to provide empirical evidence for the lookahead behavior of pedestrians in bi-directional *** find that the velocity of pedestrians is negatively correlated with not only the densities of the opposite-direction and the identical-direction pedestrians around them but also the densities of the same-direction pedestrians ahead of ***,the movement of pedestrians is most affected by other pedestrians moving in the same direction about 1 m ahead.

关键词： directional identical ahead