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journal of Materials Science & Technology 2023年第12期143卷 242-252页

作者： H.T.jeong W.j.kim Department of Materials Science and Engineering Hongik UniversityMapo-guSangsu-dong 72-1Seoul121-791Republic of Korea

The activation volume(V∗)and strain-rate sensitivity exponent(m)of cocrFeMnNi and Al_(0.5)cocrFeMnNi high entropy alloys(HEAs)with various grain sizes(ranging between 2.4 and 356μm)were measured at different strain rates and strain levels at room *** the strain rate decreased,the plastic strain decreased,and the grain size increased,V∗*** enhanced solid-solution strengthening by addition of aluminum decreased V∗.The Hassen plot was modified to capture the grain-size depen-dence of V∗by considering the grain-size dependence of the dislocation *** the plastic strain increased,the strain rate decreased,and the grain size decreased,m *** behavior of m could be quantitatively predicted by using equations derived for the grain-size-dependent V∗and flow *** difference in the grain-size dependence of m between conventional face centered cubic(Fcc)metals and Fcc HEAs over the nanograin size range could not be explained in terms of a relatively large Hall-Petch slope of the Fcc HEAs compared with that of the Fcc conventional metals,but was explainable in terms of a substantially higher probability of activation of grain-boundary diffusion-controlled grain-boundary-sliding mechanism at nanograin sizes in the Fcc conventional metals than in the Fcc HEAs.

关键词： Grain size High entropy alloys Activation volume Strain-rate sensitivity Solid solution

A Hybrid joining Technology for Aluminum/Zinc coated Steels in Vehicles

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journal of Materials Science & Technology 2010年第9期26卷 858-864页

作者： c.Y.choi D.c.kim D.G.Nam Y.D.kim Y.D.Park School of Materials Science and Engineering Pusan National UniversityBusan Advanced Welding & joining R&D Division Institute of Industrial Technology Incheon Dongnam Technology Service Division Korea Institute of Industrial TechnologyBusan Department of Advanced Materials Engineering Dong-Eui UniversityBusan

currently,in the automotive industry,joining of the aluminum alloys with the steel is a crucial problem to be *** joining techniques including resistance spot and gas metal arc welding are not acceptable for those applications due to a number of metallurgical *** investigation was carried out to develop the hybrid joining process combining the resistance spot welding and *** this study,an attempt was made to apply hybrid process to the joining of dissimilar sheet metals,Al-Mg-Si（6000 series） alloy and low carbon steel *** process（resistance spot weld/brazing） using filler metal was found to be effective to overcome the incompatibility between aluminum alloy and *** hybrid joining process of Al alloy sheet and steel sheet did not produce acceptable bond strength,it was proved to have reasonable interfacial bond layer if the optimal process condition was applied.

关键词： Hybrid joining Aluminum alloy Steel Resistance welding Brazing

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

Multiple linear regression models of urban runoff pollutant load and event mean concentration considering rainfall variables

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journal of Environmental Sciences 2010年第6期22卷 946-952页

作者： Marla c.Maniquiz Soyoung Lee Lee-Hyung kim Department of civil & Environmental Engineering Kongju National University

Rainfall is an important factor in estimating the event mean concentration （EMc） which is used to quantify the washed-off pollutant concentrations from non-point sources （NPSs）. Pollutant loads could also be calculated using rainfall, catchment area and runoff coefficient. In this study, runoff quantity and quality data gathered from a 28-month monitoring conducted on the road and parking lot sites in Korea were evaluated using multiple linear regression （MLR） to develop equations for estimating pollutant loads and EMcs as a function of rainfall variables. The results revealed that total event rainfall and average rainfall intensity are possible predictors of pollutant loads. Overall, the models are indicators of the high uncertainties of NPSs; perhaps estimation of EMcs and loads could be accurately obtained by means of water quality sampling or a long term monitoring is needed to gather more data that can be used for the development of estimation models.

关键词： event mean concentration (EMc) multiple linear regression model load non-point sources rainfall urban runoff

characteristics of contaminants in water and sediment of a constructed wetland treating piggery wastewater effluent

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journal of Environmental Sciences 2010年第6期22卷 940-945页

作者： Soyoung Lee Marla c.Maniquiz Lee-Hyung kim Department of civil & Environment Engineering Kongju National University

constructed wetland （cW） is the preferred means of controlling water quality because of its natural treatment mechanisms and function as a secondary or tertiary treatment unit. cW is increasingly applied in Korea for secondary effluent of livestock wastewater treatment. This study was conducted to recognize the characteristics of contaminants in the accumulated sediment at the bottom soil layer and to reduce the phosphorus release from sediments of the free water surface cW for the treatment of secondary piggery wastewater effluent from a livestock wastewater treatment facility. The results revealed that the dominant phosphorus existence types at near the inlet of the cW were non-apatite phosphorus （59%） and residual phosphorus （32%） suggesting that most of the particles of the influent are made up of inorganic materials and dead cells. Sediment accumulation is important when determining the long-term maintenance requirements over the lifetime of cW. continuous monitoring will be performed for a further assessment of the cW system and design.

关键词： constructed free water surface wetland piggery wastewater phosphorus type secondary wastewater effluent sediment

FATIGUE LIVES FOR INDUcTION HARDENED SHAFTS MATERIALS AccORDING TO THE ENVIRONMENTAL TEMPERATURES

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Acta Metallurgica Sinica(English Letters) 2005年第5期18卷 585-593页

作者： D.G. Lee K.c. jang j.M. Kuk I.S. kim Korea Institute of Industrial Technology Gwangju 506-824 Korea Dept. of Mechanical Engineering Mokpo National University Mokpo 534-729 Korea

Rotary bending fatigue tests were carried out with two kinds of materials, S43c and S50c, using the front engine and front drive shaft （FF shaft） of vehicle. The specimens were induction hardened about 1.0mm depth from the specimen surface, and the hardness value on the surface was about HRc56-60. The tested environment temperatures were -30, 25 and 80℃ in order to look over effect of the induction hardening and the environmental temperatures on the fatigue characteristics. The fatigue limit of induction hardened specimens increased more about 45% than non-hardened specimens showing that the endurances of S43c and S50c were 98.1 and 107.9MPa in non-hardened samples, 147.1 and 156.9MPa in hardened samplesrespectably. The maximum tensile and compressive stress on the small circular defect was about ＋250 and -450MPa respectively when circular defect is situated on top and bottom. The fatigue life increased 80, 25 and -30℃ in order regardless of hardening. In comparison of the fatigue lives on the basis of tested result at 25℃, the fatigue lives of non-hardened specimens decreased about 35%, but that of hardened specimens decreased about only 5% at 80℃ more than at 25℃. And fatigue life of non-hardened and hardened specimens were about 110% and 120% higher at -30℃ than that of 25℃. Based on the result of stress distribution near the defect, the tensile and compressive stress repeatedly generated by load direction were the largest on the small circular defect due to the stress concentration.

关键词： induction hardening fatigue test front engine and front drive shaft,fatigue crack fatigue life fatigue life ratio

The Stanley Neuropathology consortium Integrative Database (SNcID) for Psychiatric Disorders

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Neuroscience Bulletin 2019年第2期35卷 277-282页

作者： Sanghyeon kim Maree j.Webster Stanley Brain Research Laboratory Stanley Medical Research Institute

The Stanley Medical Research Institute(SMRI)is a nonprofit organization with a primary mission to fund research on the cause and treatment of severe mental *** SMRI also supports a brain bank as part of the mission to facilitate research into mental *** SMRI brain bank distributes postmortem samples from individuals with serious mental illness,free of charge,to scientists around the *** SMRI brain bank is recognized for the unique way it is set up,organized,and *** of demographically-matched groups of patients with schizophrenia,bipolar disorder(BP),or major depression(DEP)and unaffected controls are organized such that all researchers applying for tissue received samples from the same cohort.

关键词： SNcID for Psychiatric Disorders DRD RNA

Aqueous-processable,naphthalene diimide-based polymers for eco-friendly fabrication of high-performance,n-type organic electrolyte-gated transistors

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Science china chemistry 2022年第5期65卷 973-978页

作者： Dahyun jeong Min je kim Seungjin Lee jin-Woo Lee Youngwoong kim Hyeong jun kim jeong Ho cho Bumjoon j.kim Department of chemical and Biomolecular Engineering Korea Advanced Institute of Science and Technology(KAIST)Daejeon 34141Republic of Korea Department of chemical and Biomolecular Engineering Yonsei UniversitySeoul 03722Republic of Korea Department of chemical and Biomolecular Engineering Sogang UniversitySeoul 04107Republic of Korea

Organic electrolyte-gated transistors(OEGTs) have the benefits of low power consumption and large current ***,the electrical performance of n-type OEGTs lags far behind that of p-type *** this study,we design a series of polymers,P(NDITEG-T) and P(NDIMTEG-T),comprising a naphthalene diimide backbone for n-type charge transport and oligo(ethylene glycol)(OEG) side chains for high ionic conductivity and eco-friendly solution *** incorporation of the OEG chain facilitates the electrochemical doping of the semiconductor by ions to realize high-performance,n-type ***,in OEGTs,P(NDITEG-T) achieves a high electron mobility of 1.0 × 10^(-1) cm^(2) V^(-1) s^(-1),which represents the highest value reported for solution-processed,n-type *** is noted that the fabrication of the OEGTs is achieved by solution processing with eco-friendly ethanol/water mixtures in virtue of the hydrophilic OEG *** work demonstrates the molecular design of the P(NDITEG-T) polymer and its significant ability to produce aqueous-processable,high-performance,and n-type OEGTs.

关键词： organic electrolyte-gated transistors n-type transistors oligo(ethylene glycol)polymers eco-friendly solution process high electron mobility

Difference in the Hot compressive Behavior and Processing Maps between the As-cast and Homogenized Al-Zn-Mg-cu(7075) Alloys

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journal of Materials Science & Technology 2016年第7期32卷 660-670页

作者： S.Y. Park W.j. kim Department of Materials Science and Engineering Hongik University 72-1 Sangsu-dong Mapo-gu Seoul 121-791 Republic of Korea Advanced Fusion Process R&D Group Korea Institute of Industrial Technology 994-32 Dongchun-dong Yeonsu-gu Incheon 406-130 Republic of Korea

The deformation mechanisms and processing maps of the as-cast Al-Zn-Mg-cu （？0？5） aluminum （AI） alloy were studied and compared with those of the homogenized 7075 Al alloy in the temperature range of 573-723 K and in the strain rate range of 10 3-10 s-1 to explore a possibility for directly using the as- cast 7075 Al alloy as a billet for hot working. The as-cast and homogenized 7075 A1 alloys had similar grain sizes and showed similar high-temperature deformation behaviors. The as-cast 7075 Al alloy, however, exhibited higher power efficiencies and smaller unstable flow regions compared to the homogenized 7075 AI alloy because of the presence of secondary phases （MgZn2） segregated at the dendritic interfaces in the as-cast microstructure, which were formed during non-equilibrium solidification. These segregated phases provided nucleation sites for dynamic recovery or continuous dynamic recrystallization, and as a result a fine and more homogeneous （sub）grain structure could be obtained from the as-cast micro- structure compared to the homogenized microstructure. The current work suggested the possibility and advantage of using as-cast microstructures for hot working of aluminum alloys with high content of solutes.

关键词： Al-based alloysProcessing mapHot compressionAs-cast microstructureSegregationRecrystallization

The hot compressive deformation behavior of cast Mg-Gd-Y-Zn-Zr alloys with and without LPSO phase in their initial microstructures

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journal of Magnesium and Alloys 2022年第10期10卷 2901-2917页

作者： H.T.jeong W.j.kim Departmentof Materials Science and Engineering Hongik UniversityMapo-guSangsu-dong 72-1Seoul 121-791Republic of Korea

Samples of Mg-8.2Gd-3.8Y-1.1Zn-0.4Zr alloy with and without an intragranular lamellae-shaped long period stacking ordered(LPSO)phase were prepared through heat treatment and a series of hot compression tests on these materials were conducted to examine and evaluate the influence of LPSO on the hot compressive deformation behavior and deformation mechanisms at a given alloy *** values of activation energy for plastic flow(Qc)of the solution treated(without LPSO phase)and annealed alloys(with intragranular LPSO phase)were larger than that for pure Mg,indicating that the presence of a high amount of rare earth(RE)elements and LPSO in the Mg matrix significantly increases *** Qcvalue of the annealed alloy was larger than that of the solution treated alloy at all the strain levels(223.3 vs.195.5 k j/mol in average)and the largest difference in Qcbetween the two alloys was recorded at the smallest strain of 0.1 where precipitation of LPSO during deformation was limited in the solution treated *** observations imply that the formation of LPSO phase out of the RE-rich solid solution matrix during deformation increases Qc,but the increment is not so *** of the hot compressive data of the alloys with LPSO phase and the alloys with RE-rich solid solution matrix in literatures indicates the similarity of the effect of the LPSO and RE-rich solid solution matrix phases on Qcand high-temperature strength.

关键词： Magnesium alloys LPSO Deformation mechanism Dynamic recrystallization Activation energy for plastic flow Processing maps