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Calculation of the Transition Temperature for Partitioned Growth of Proeutectoid Ferrite in Fe-C Base Multicomponent Alloys

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Journal of Iron and Steel Research International 2011年第S1期18卷 530-534页

作者： suh dong-woo Graduate Institute of Ferrous Technology Pohang University of Science and TechnologyPohang 790-784Republic of Korea

According to the local equilibrium theory,the ferrite growth from alloyed austenite could be divided into the partition local equilibrium (PLE) mode and negligible partition local equilibrium (NPLE) mode.A graphical construction method proposed earlier by Hillert using in Fe-C-X ternary alloys was extended into Fe-C base multicomponent alloys to calculate the PLE/NPLE transition *** method utilize the carbon component ray,in which the substitutional alloy elements content is constant,to determine PLE/NPLE transition *** the method,the PLE/NPLE transition temperature in several alloy systems are calculated and compared with the formerly reported results.

关键词： phase transformation local equilibrium kinetics ferrite PLE/NPLE transition

Embedded Surfaces for Symplectic Circle Actions

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Chinese Annals of Mathematics,Series B 2017年第6期38卷 1197-1212页

作者： Yunhyung CHO Min Kyu KIM dong Youp suh Department of Mathematics Education Sungkyunkwan UniversitySeoulRepublic of Korea. Department of Mathematics Education Gyeongin National University of EducationSan 59-12Gyesan-dongGyeyang-guIncheon 407-753Republic of Korea. Department of IVIathematieal Sciences KAIST335 GwahangnoYu-sung GuDaejeon 305-701Republic of Korea.

The purpose of this article is to characterize symplectic and Hamiltonian circle actions on symplectic manifolds in terms of symplectic embeddings of Riemann *** precisely, it is shown that(1) if(M, ω) admits a Hamiltonian S^1-action, then there exists a two-sphere S in M with positive symplectic area satisfying c1(M, ω), [S] > 0,and(2) if the action is non-Hamiltonian, then there exists an S^1-invariant symplectic2-torus T in(M, ω) such that c1(M, ω), [T] = 0. As applications, the authors give a very simple proof of the following well-known theorem which was proved by Atiyah-Bott,Lupton-Oprea, and Ono: Suppose that(M, ω) is a smooth closed symplectic manifold satisfying c1(M, ω) = λ· [ω] for some λ∈ R and G is a compact connected Lie group acting effectively on M preserving ω. Then(1) if λ 0, then the G-action is Hamiltonian.

关键词： Symplectic geometry Hamiltonian action

Effect of Al addition on corrosion behavior of high-purity Mg in terms of processing history

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Journal of Magnesium and Alloys 2023年第3期11卷 851-868页

作者： Sang Kyu Woo Byeong-Chan suh Ha Sik Kim Chang dong Yim Helmholtz Zentrum Hereon Max-Planck-Straße 1Geesthacht D-21502Germany Korea Institute of Materials Science 797 Changwondae-roSeongsan-guChangwonGyeongnam 51508Republic of Korea University of Science and Technology 217 Gajeong-roYuseong-guDaejeon 34113Republic of Korea

In this study,the effects of Al addition on the corrosion behavior of pure Mg with controlled impurity contents were systematically analyzed according to the processing *** results revealed that the corrosion behavior of high-purity Mg-Al alloys is strongly related to changes in the microstructure,including theβphase and Al-Mn or Al-Fe phases,and the protectiveness of the surface film according to the Al content and processing *** the as-cast alloys,the corrosion rate increased due to the increase ofβphase as the Al content increased,but in the as-extruded alloys,the corrosion rate,which was high due to intermetallic compounds caused by impurities in the low Al alloy,decreased as the Al content increased,and then increased *** is due to the combined effect of the increase of theβphase and decrease of the impurity effect,and the increase of the dissolved Al *** results suggest that it is necessary to analyze the effect of alloying elements on the corrosion behavior of pure Mg with information concerning the impurity content and processing history.

关键词： Mg High purity Mg-Al alloys Processing history Micro-galvanic Surface film

Numerical analysis of three-dimensional thermo-elastic rolling contact under steady-state conditions

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Friction 2022年第4期10卷 630-644页

作者： Yonghun YU Junho suh Department of Mechanical Engineering Pusan National UniversityBusan SW72AZRepublic of Korea

In this study,a three-dimensional thermo-elastic model that considers the interaction of mechanical and thermal deformation is developed using a semi-analytic method for steady-state rolling *** types in all directions are considered in this *** verification,the numerical analysis results of shear traction and temperature increase are compared separately with existing numerical results,and the consistency is *** analysis results include heat flux,temperature increase,contact pressure,and shear *** severe rolling conditions,the thermal effect changes the behavior of the contact interface ***,the effects of creepage,rolling speed,and conformity under different rolling and creep conditions are investigated.

关键词： creep frictional heat rolling contact spin thermal deformation

Enhancement of ballistic performance enabled by transformation-induced plasticity in high-strength bainitic steel

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Journal of Materials Science & Technology 2021年第25期84卷 219-229页

作者： Min Cheoljo Selim Kim dong Woo suh Hong Kyu Kim Yongjin Kim Seok Su Sohn Sunghak Lee Center for Advanced Aerospace Materials Pohang University of Science and TechnologyPohang37673South Korea Graduate Institute of Ferrous Technology Pohang University of Science and TechnologyPohang37673South Korea Materials Directorate Agency for Defense DevelopmentDaejeon305-600South Korea Department of Materials Science and Engineering Korea UniversitySeoul02841South Korea

High-strength bainitic steels have created a lot of interest in recent times because of their excellent combination of strength,ductility,toughness,and high ballistic mass *** steels have great potential in the fabrication of steel armor *** various approaches and methods have been conducted to utilize the retained austenite(RA)in the bainitic matrix to control mechanical properties,very few attempts have been conducted to improve ballistic performance utilizing transformationinduced plasticity(TRIP)*** this study,high-strength bainitic steels were designed by controlling the time of austempering process to have various volume fractions and stability of RA while maintaining high *** dynamic compressive and ballistic impact tests were conducted,and the relation between the effects of TRIP on ballistic performance and the adiabatic shear band(ASB)formation was *** results show for the first time that an active TRIP mechanism achieved from a large quantity of metastable RA can significantly enhance the ballistic performance of high-strength bainitic steels because of the improved resistance to ASB ***,the ballistic performance can be effectively improved by a very short austempering time,which suggests that the utilization of active TRIP behavior via tuning RA acts as a primary mechanism for significantly enhancing the ballistic performance of high-strength bainitic steels.

关键词： High-strength bainitic steel Ballistic performance Split Hopkinson pressure bar(SHPB) Adiabatic shear band(ASB) Retained austenite(RA) Transformation-induced plasticity(TRIP)

An investigation of the microstructural effects on the mechanical and electrochemical properties of a friction stir processed equiatomic CrMnFeCoNi high entropy alloy

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Journal of Materials Science & Technology 2021年第28期87卷 60-73页

作者： sam Yaw Anaman Solomon Ansah Hoon-Hwe Cho Min-Gu Jo Jin-Yoo suh Minjung Kang Jong-Sook Lee Sung-Tae Hong Heung Nam Han Department of Materials Science and Engineering Hanbat National University125 Dongseodae-roYuseong-GuDaejeonRepublic of Korea Center for Energy Materials Research Clean Energy InstituteKorea Institute of Science and TechnologySeoul02792Republic of Korea Department of Materials Science and Engineering&Research Institute of Advanced Materials Seoul National University1Gwanak-roGwanak-guSeoul08826Republic of Korea Advanced Functional Technology R&D Department Korea Institute of Industrial TechnologyIncheon21999Republic of Korea School of Materials Science and Engineering Chonnam National UniversityGwangju61186Republic of Korea School of Mechanical Engineering University of UlsanUlsan680-749Republic of Korea

The electrochemical properties of a friction stir processed(FSPed)equiatomic CrMnFeCoNi high-entropy alloy(HEA)was investigated in an aerated 0.5 M Na_(2)SO_(4) electrolyte solution at room *** microstructural analysis reveals a highly refined stir zone(SZ)with an average grain size that decreases from the top region of the SZ to the bottom region of the SZ(also known as shear-processed zone;SPZ).However,the region below the SPZ,(*** the plunge depth)experienced an increase in average grain size and dislocation densities compared to the other *** is no secondary phase observed in the FSPed region,however,the microstructural evolution in the FSPed region affects the electrochemical behavior of the ***_(2)O_(3) passive layer was observed to form on the FSPed HEA,leading to excellent corrosion properties from the polarization corrosion *** refinement in the SZ enhances the rapid formation of the passive layer,thus,leading to better corrosion properties in the front surface of the FSPed *** localized corrosion behavior of the FSPed HEA was predicted to be caused by the micro-galvanic nature of the HEA,which leads to an increase in polarization at the anodic sites(pits).A numerical model was established using the corrosion parameters from the experiment to simulate the localized corrosion behavior on the surface of the FSPed HEA in a neutral *** predicted initial pitting potential and corresponding current density agree well with the experimental *** model is also capable of tracking the dissolution of the pits over longer periods.

关键词： High entropy alloys Friction stir processing Grain refinement Passive film Pitting Simulation

Pseudo-anti commuting Ricci tensor for real hypersurfaces in the complex hyperbolic quadric

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Science China Mathematics 2019年第4期62卷 679-698页

作者： Young Jin suh Department of Mathematics & Research Institute of Real and Complex Manifolds College of Natural SciencesKyungpook National University

We introduce a new notion of pseudo-anti commuting Ricci tensor for real hypersurfaces in the noncompact complex hyperbolic quadric Q^(m?)= SO_2~0,_m/SO_2SO_m and give a complete classi?cation of these hypersurfaces.

关键词： pseudo-anti commuting Ricci tensor pseudo-Einstein A-isotropic A-principal complex conjugation complex hyperbolic quadric

TT virus and hepatitis G virus infections in Korean blood donors and patients with chronic liver disease

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World Journal of Gastroenterology 2003年第4期9卷 741-744页

作者： Mee Juhng Jeon Jong Hee Shin Soon Pal suh Young Chai Lim dong Wook Ryang Division of Medical Research Kwangju-Chonnan Red Cross Blood CenterChonnam National UniversityKwangju Republic of Korea Department of Clinical Pathology Chonnam National UniversityKwangju Republic of Korea Research Institute of Medical SciencesChonnam Nationa UniversityKwangjuRepublic of Korea Department of Pharmacology Medical SchoolChonnam National UniversityKwangjuRepublic of Korea Research Institute of Medical SciencesChonnam National UniversityKwangjuRepublic of Korea Department of Clinical Pathology Chonnam National UniversityKwangjuRepublic of Korea Research Institute of Medical Scienceschonnam National UniversityKwangjuRepublic of Korea

AIM:To determine the prevalences of TTV and HGV infections among blood donors and patients with chronic liver disease in Korea,to investigate the association of TTV and HGV infections with blood transfusion,and to assess the correlation between TTV and HGV viremia and hepatic damage. METHODS:A total of 391 serum samples were examined in this *** were obtained from healthy blood donors(n=110),hepatitis B surface antigen(HBsAg)-positive donors(n=112),anti-hepatitis C virus(anti-HCV)-positive donors(n=69),patients with type B chronic liver disease (n=81),and patients with type C chronic liver disease(n=19). Trv DNA was detected using the hemi-nested *** RNA was tested using RT-PCR.A history of blood transfusion and serum levels of alanine aminotransferase(ALT)and aspartate aminotransferase(AST)were also determined. RESULTS:TTV DNA was detected in 8.2%of healthy blood donors,16.1%of HBsAg-positive donors,20.3%of anti- HCV-positive donors,21.0%of patients with type B chronic liver disease,and 21.1%of patients with type C chronic liver *** RNA was detected in 1.8%of healthy blood donors,1.8%of HBsAg-positive donors,17.4%of anti-HCV-positive donors,13.6%of patients with type B chronic liver disease,and 10.5%of patients with type C chronic liver *** prevalence of TTV and HGV infections in HBV- or HCV-positive donors and patients was significantly higher than in healthy blood donors(Psame as for healthy *** was a history of transfusion in 66.7%of TTV DNA-positive patients and 76.9%of HGV RNA-positive patients(P<0.05).No significant increase in serum ALT and AST was detected in the TTV or HGV-positive donors and patients. CONCLUSION:TTV and HGV infections are more frequently found in donors and patients infected with HBV or HCV than in healthy blood ***,there is no significant association between TTV or HGV infections and liver injury.

关键词： Blood Donors Blood Transfusion Chronic Disease DNA Virus Infections DNA, Viral Flaviviridae Infections GB virus C purification Hepatitis B Surface Antigens Hepatitis, Viral, Human Korea Liver Diseases Polymerase Chain Reaction Reference Values Reverse Transcriptase Polymerase Chain Reaction Torque teno virus

Equivariant Cobordism of Torus Orbifolds

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Chinese Annals of Mathematics,Series B 2021年第6期42卷 861-890页

作者： Soumen SARKAR dongYoup suh Department of Mathematics Indian Institute of Technology MadrasChennai 600036India Department of Mathematical Sciences KAISTDaejeon 305701Republic of Korea

Torus orbifolds are topological generalizations of symplectic toric *** authours give a construction of smooth orbifolds with torus actions whose boundary is a disjoint union of torus orbifolds using a toric topological *** a result,they show that any orientable locally standard torus orbifold is equivariantly cobordant to some copies of orbifold complex projective *** also discuss some further equivariant cobordism results including the cases when torus orbifolds are actually torus manifolds.

关键词： Manifold with corners Torus action Torus orbifolds Equivariant cobordism