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Origin of superior low-cycle fatigue resistance of an interstitial metastable high-entropy alloy

Journal of Materials Science & Technology 2022年第20期115卷 115-128页

作者： Seyed Amir Arsalan Shams jae Wung Bae jae Nam Kim Hyoung Seop Kim Taekyung lee Chong Soo lee Graduate Institute of Ferrous Technology Pohang University of Science and TechnologyPohang 37673Republic of Korea Department of Materials Science and Engineering Pohang University of Science and TechnologyPohang 37673Republic of Korea School of Mechanical Engineering Pusan National UniversityBusan 46241Republic of Korea

In this study, the deformation behaviors and related microstructural evolutions were investigated in either monotonic or cyclic deformation modes in an interstitial metastable high-entropy alloy. These investigations aimed to reveal the mechanisms underlying the superior low-cycle fatigue(LCF) life of this alloy.A thermomechanical process was applied to induce fine-grained(FG) and coarse-grained(CG) microstructures in Fe–30Mn–10Co–10Cr–0.4C(atomic percentage) alloy. Their superior combination of strength and ductility was attributed to the appearance of deformation-induced ε-martensite and the presence of carbon. The CG alloy showed a greater volume fraction of ε-martensite than the FG alloy in the monotonic deformation mode, and vice versa in the cyclic mode. Such a disparity was interpreted in light of the back-stress effect of the relaxed γ-grain boundaries in the latter mode. Meanwhile, the γ-to-ε phase transformation under cyclic loading at low strain amplitudes(0.4%) barely led to an improved fatigue life as compared with that at higher strain amplitudes(≥ 0.55%). The high reversibility of partial dislocation motions under cyclic loading and delaying the formation of dislocation cells through the martensitic transformation could explain why the alloys investigated in this study exhibited a superior LCF life compared with high-entropy alloys reported in previous studies.

关键词： High-entropy alloy Transformation-induced plasticity Monotonic deformation Cyclic deformation Low-cycle fatigue Stacking faults

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Development of Non-Dissipative Direct Time Integration Method for Structural Dynamics Application

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Computer Modeling in Engineering & Sciences 2019年第1期118卷 41-89页

作者： Sun-Beom Kwon jae-Myung lee Department of Naval Architecture and Ocean Engineering Pusan National UniversityJangjeon-DongGeumjeong-GuBusan 609-735Korea.

A direct time integration scheme based on Gauss-Legendre quadrature is proposed to solve problems in linear structural *** proposed method is a oneparameter non-dissipative *** stability,accuracy,and dispersion characteristics are achieved using appropriate values of the *** proposed scheme has second-order accuracy with and without physical ***,its stability,accuracy,and dispersion are *** addition,its performance is demonstrated by the two-dimensional scalar wave problem,the single-degree-of-freedom problem,two degrees-of-freedom spring system,and beam with boundary *** wave propagation problem is solved in the high frequency wave regime to demonstrate the advantage of the proposed *** the proposed scheme is applied to solve the wave problem,more accurate solutions than those of other methods are obtained by using the appropriate value of the *** the single-degree-offreedom system,two degrees-of-freedom system,and the time responses of beam,the proposed scheme can be used effectively owing to its high accuracy and lower computational cost.

关键词： Structural dynamics finite elements direct time integration Gauss-Legendre quadrature non-dissipative scheme.

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Development of two-axis control index table driven by direct drive motors

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Journal of Central South University 2011年第6期18卷 1962-1968页

作者： KIM jae-hyun lee Choon-man School of Mechatronics Changwon National University

The stability and reliability of a tilting index table should be considered at the design stage. A design method for the lightweight and improvement of the stability of the structure in a tilting index table was proposed using a commercial analysis program, ANSYS Workbench 12, by analyzing the static-thermal characteristics of the developed high-accuracy tilting index table at its design stage. The results of the performed structural analysis show that the maximum stress is generated at the stock tail part. An optimum design for the stock tail part was carried out to reduce the maximum stress and deformation. Also, the design variables were determined by considering the support of the stock tail part for the C-axis body. In the comparison of the results before and after the optimization, the maximum deformation and stress are improved by 2.8% and 8%, respectively.

关键词： tilting index table structural analysis modal analysis thermal analysis optimum design

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Generation of double knockout cattle via CRISPR-Cas9 ribonucleoprotein(RNP)electroporation

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Journal of Animal Science and Biotechnology 2024年第1期15卷 456-462页

作者： Gyeong-Min Gim Kyeong-Hyeon Eom Dong-Hyeok Kwon Dae-Jin Jung Dae-Hyun Kim Jun-Koo Yi jae-Jung Ha Ji-Hyun lee Seong-Beom lee Woo-jae Son Soo-Young Yum won-Wu lee Goo Jang Laboratory of Theriogenology and Biotechnology Department of Veterinary Clinical ScienceCollege of Veterinary Medicine and the Research Institute of Veterinary ScienceSeoul National UniversitySeoulRepublic of Korea LARTBio Co. Ltd.SeoulRepublic of Korea Gyeongsangbukdo Livestock Research Institute YeongjuRepublic of Korea Comparative Medicine Disease Research Center Seoul National UniversitySeoulRepublic of Korea

Background Genome editing has been considered as powerful tool in agricultural ***,genome editing progress in cattle has not been fast as in other mammal species,for some disadvantages including long gestational periods,single pregnancy,and high raising ***,technically demanding methods such as microinjection and somatic cell nuclear transfer(SCNT)are needed for gene editing in *** this point of view,electroporation in embryos has been risen as an *** First,editing efficiency of our electroporation methods were tested for *** of mutation on embryo was confirmed by T7E1 *** first combination,mutation rates for MSTN and PRNP were 57.6%±13.7%and 54.6%±13.5%,*** case of MSTN/BLG,mutation rates were 83.9%±23.6%for MSTN,84.5%±18.0%for ***,the double-KO embryos were transferred to surrogates and mutation rate was identified in resultant calves by targeted deep *** recipients were transferred for MSTN/PRNP,4 calves were delivered,and one calf underwent an induction for double *** surrogates were given double-KO embryos for MSTN/BLG,and four of the six calves that were born had mutations in both *** These data demonstrated that production of genome edited cattle via electroporation of RNP could be effectively ***,MSTN and PRNP from beef cattle and MSTN and BLG from dairy cattle have been born and they will be valuable resources for future precision breeding.

关键词： Beta-lactoglobulin Cattle CRISPR-Cas9 Electroporation Knockout MSTN PRNP

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Prothrombin kringle-2, a mediator of microglial activation: new insight in Alzheimer’s disease pathogenesis

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Neural Regeneration Research 2022年第12期17卷 2675-2676页

作者： jae Man lee Sang Ryong Kim Department of Biochemistry and Cell Biology Cell and Matrix Research InstituteSchool of MedicineKyungpook National UniversityDaeguKorea Brain Science and Engineering Institute Kyungpook National UniversityDaeguKorea School of Life Sciences BK21 FOUR KNU Creative BioResearch GroupInstitute of Life Science and BiotechnologyKyungpook National UniversityDaeguKorea

Microglial activation in Alzheimer’s disease(AD):In 1907,*** Alzheimer,a Bavarian-born German psychiatrist and neuropathologist,published an article describing the clinical and neuropathological features of an unclassified psychiatric *** disorder was later named AD and is currently the most common brain disorder(Takata et al.,2021).AD involves the accumulation of amyloid-β(Aβ)and hyperphosphorylated tau proteins in the brain,which are associated with senile plaques and neurofibrillary tangles,respectively(Vergara et al.,2019;Takata et al.,2021).AD is characterized by cognitive impairment and memory loss with hippocampal neurodegeneration(Kim et al.,2021).

关键词： Alzheimer Aβ tau

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Development of oxide dispersion strengthened ferritic steels with and without aluminum

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Frontiers in Energy 2012年第1期6卷 29-34页

作者： jae Hoon lee Sheet Products&Process Research Gr. POSCO Technical Research Laboratories 699Gumho-dongGwangyang-siJeonnam 545-090Republic of Korea

Pure Fe, Cr, AI, Ti elemental powders and prealloyed Y203 powder were processed by high energy mechanical milling. The compositions of the mixed powders are designed as Fe-18Cr-0.2Ti-0.35Y2O3 and Fe-18Cr-5Al-0.2Ti-0.35Y2O3 in weight percent. The asmilled powders were consolidated by hot extrusion at 1423 K. The dispersed oxide particles were identified to be titania ＋ yttria for Al-free oxide dispersion strengthened （ODS） steel and alumina ＋ yttria for Al-added ODS steel, respectively. The ultimate tensile strength of Al-free ODS steel was higher than that of Al-added ODS steel over the temperature range of 298-973 K, because of the difference in number density and size of thermally stable oxide particles dispersed in both steel matrices. The strength in the longitudinal direction was lower than that in the transverse direction, probably due to anisotropy of the microstructure with elongated grains in the hot-extrusion direction for the 18%Cr-ODS steels with and without 5% Al.

关键词： oxide dispersion strengthened (ODS) steel,milling extrusion aluminum yttria

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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

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Electrochemical characteristics of phosphorus doped Si-C composite for anode active material of lithium secondary batteries

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中国有色金属学会会刊：英文版 2009年第4期19卷 1018-1022页

作者： jae-Hyun NOH Kwan-Yo ung lee Joong-Kee lee Battery Research Center Korea Institute of Science and Technology Department of Chemical and Biological Engineering Korea University

Phosphorus doped silicon-carbon composite particles were synthesized through a DC arc plasma ***(SiH4) and methane(CH4) were introduced into the reaction chamber as the precursor of silicon and carbon,***(PH3) was used as a phosphorus dopant *** of synthesized particles were carried out by scanning electron microscopy(SEM),X-ray diffractometry(XRD),X-ray photoelectron spectroscopy(XPS) and bulk resistivity *** properties were investigated by cyclic test and electrochemical voltage spectroscopy(EVS).In the experimental range,phosphorus doped silicon-carbon composite electrode exhibits enhanced cycle performance than intrinsic silicon and phosphorus doped *** can be explained that incorporation of carbon into silicon acts as a buffer matrix and phosphorus doping plays an important role to enhance the conductivity of the electrode,which leads to the improvement of the cycle performance of the cell.

关键词：电化学特性磷掺杂负极活性材料磷硅电池材料锂离子 X射线光电子能谱扫描电子显微镜

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Smooth cutting pattern generation technique for membrane structures using geodesic line on subplane and spline interpolation

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Journal of Central South University 2013年第11期20卷 3131-3141页

作者： SHON Su-deok lee Seung-jae lee Kang-guk School of Architectural Engineering Korea University of Technology and Education Research Center for Building safety Kyungpook National University

Practical techniques for smooth geodesic patterning of membrane structures were *** the geodesic search,adjustment of the subplane of the extracted elements series was proposed,and various spline approximation methods were used to flatten the strip for the generation of a smooth *** search approach is very simple,and the geodesic line could be easily attained by the proposed method without the need for a difficult computation *** cutting patterning can also be generated by spline approximation without the noise in discrete nodal ***,the geodesic cutting pattern saved about 21%of the required area for the catenary model due to the reduction of the curvature of the planar pattern seam line.

关键词： membrane structures cutting pattern generation geodesic line spline interpolation triangular mesh sub-plane

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W-translated Schubert divisors and transversal intersections

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Science China Mathematics 2022年第10期65卷 1997-2018页

作者： DongSeon Hwang Hwayoung lee jae-Hyouk lee Changzheng Li Department of Mathematics Ajou UniversitySuwon 443-749Republic of Korea Department of Mathematics University of CaliforniaRiversideRiversideCA 92521USA Department of Mathematics Ewha Womans UniversitySeoul 120-750Republic of Korea School of Mathematics Sun Yat-sen UniversityGuangzhou 510275China

We study the toric degeneration of Weyl group translated Schubert divisors of a partial flag variety F?_(n1,...,nk;n) via Gelfand-Cetlin polytopes. We propose a conjecture that Schubert varieties of appropriate dimensions intersect transversally up to translation by Weyl group elements, and verify it in various cases,including the complex Grassmannian Gr(2, n) and the complete flag variety F?_(1,2,3;4).

关键词： W-translated Schubert varieties transversal intersection Gelfand-Cetlin polytope toric degeneration flag varieties

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