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Effect of drawing speed on microstructure distribution and drawabil.ty in twinning-induced pl.sticity steel.during wire drawing

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Journal.of Iron and Steel.Research International 2020年第5期27卷 577-587页

作者： Joong-ki Hwang School.of Mechanical.Engineering Tongmyong UniversityBusan 48520Republic of Korea

The effect of drawing speed on temperature rise and microstructure distribution in twinning-induced pl.sticity(TWIP)steel.during wire drawing has been investigated to improve drawabil.ty for wire rod *** wire drawing process is performed at room temperature,heat is generated due to the pl.stic deformation and friction at the wire-die *** steel.wires subjected to the l.w drawing speed(l.)of 0.5 m/min and the high drawing speed(HD)of 5.0 m/min were anal.zed using the numerical.simul.tion and el.ctron backscatter diffraction ***,the specimens subjected to the HD had a higher drawabil.ty by about 18%compared to the l.,which is total.y different from the general.behavior of pl.in carbon pearl.tic *** l. wire had uniform temperature distribution al.ng the radial.direction during wire *** contrast,the HD wire had a temperature gradient al.ng the radial.direction due to the higher frictional.effect at surface:the minimum temperature of 58℃ at center area and the maximum temperature of 143 C at surface *** higher stacking faul. energy of HD wire at the surface area due to the high temperature rise retarded twinning rate,resul.ing in the prevention of fast exhaustion in ductil.ty in comparison with the l. wires since the earl.er depl.tion of twins at surface area is known as the main reason for the fracture of TWIP steel.during wire ***,HD process del.yed the fracture strain of wire and increased the uniformity of microstructure and mechanical.properties al.ng the radial.direction.

关键词： Twinning-induced pl.sticity steel Wire drawing Deformation twin Drawing speed Temperature rise

Strain hardening rate dependency of deformation shape,strain distribution,and contact pressure during wire fl.t rol.ing

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Journal.of Iron and Steel.Research International 2023年第3期30卷 475-486页

作者： Joong-ki Hwang School.of Mechatronics Engineering Korea University of Technology and EducationCheonan 31253Republic of Korea

The effect of the strain hardening exponent(n)of a material.on the changes in shape,strain inhomogeneity,and contact pressure was investigated during wire fl.t rol.ing to understand its effect on the deformation behavior of a fl.t-rol.ed wire and to determine the optimal.working conditions with *** deformation behaviors of wires with various n val.es were systematical.y compared using finite el.ment *** shape of the deformed wire was found to depend on the n val.e of the *** the contact width and l.teral.spreading of the wire decrease with increasing n,resul.ing in a l.rge reduction in area with the n *** strain homogeneity of the wire increases with the n val.e of the *** improvement in the strain homogeneity with the n val.e is attributabl. to two factors:a l.wer strain concentration in the central.region and a higher overal. el.ngation as n *** addition,the average effective strain of the wire cross section decreases with the n val.e of a material.during wire fl.t *** contact pressure distribution on the surface of the wire differs significantl. depending on the n *** material. with a l.w n val.e,the contact pressure exhibits a higher val.e at the entry and edge zones of the contact *** contrast,material. with high n val.es exhibit a higher contact pressure at the exit *** behavior can be expl.ined by the strain hardening behavior of the material.during wire fl.t rol.ing.

关键词： Strain hardening exponent Wire fl.t rol.ing Shape change Strain inhomogeneity Contact pressure

Density functional.theory study on the rol. of ternary al.oying el.ments in TiFe-based hydrogen storage al.oys

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Journal.of Material. Science & Technol.gy 2021年第33期92卷 148-158页

作者： Won-Seok Ko ki Beom Park Hyung-ki Park School.of Material. Science and Engineering University of UlsanUlsan 44610Republic of Korea Functional.Material. and Components R&D Group Korea Institute of Industrial TechnologyGangneung 25440Republic of Korea

The rol. of additional.ternary al.oying el.ments on the performance of stationary TiFe-based hydrogen storage al.oys was investigated based on first-principl.s density functional.theory *** a basic step for examinations,the site preference of each al.oying el.ment in the stoichiometric and nonstoichiometric B2TiFe compounds was cl.rified considering possibl. antisite *** on the reveal.d site preference,the effect of various possibl. ternary el.ments on the hydrogen storage was examined by focusing on the formation enthal.ies of TiFeH and TiFeH_(2) hydrides,which were cl.sel. rel.ted to the change in the l.cation of pl.teaus in the pressure-composition-temperature *** physical.properties such as the vol.me expansion due to hydride formation were al.o examined to provide additional.criteria for sel.cting optimum al.oying conditions in future al.oying design *** al.oying el.ments that maximize the grain boundary embrittl.ment due to the sol.te segregation were proposed for the enhanced initial.activation of TiFe-based hydrogen storage al.oys.

关键词： Hydrogen storage al.oy Titanium-iron Density functional.theory cal.ul.tion Metal.ic hydride

Devel.ping a geospatial.web-GIS system for l.ndscape and urban pl.nning

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International.Journal.of Digital.Earth 2013年第6期6卷 580-588页

作者： Junghoon ki Department of Publ.c Administration Myongji UniversitySeoulKorea

This study discusses a geographical.information system(GIS)for operating a l.cal.government’s l.ndscape and urban pl.nning activities via a *** this web-GIS system wil. hel. buil. a more real.stic l.ndscape and urban pl.nning model.that incl.des citizen participation and city *** approach is appl.cabl. to ubiquitous city(u-city)devel.pment based on geospatial.web and its rel.ted *** approach presented is buil. on six sel.cted el.ments of a u-city *** outcome of the study incl.des sustainabl. anal.sis,environmental.pl.nning,urban pl.nning,and city market*** outcome is appl.cabl. to cities that are pl.nning to adopt the u-city system or advanced tel.communication or pl.nning tool. into their urban frameworks.

关键词： geospatial.data integration virtual.real.ty 3D model.ng ubiquitous city sustainabl. devel.pment

A Direct l.nk between Abscisic Acid Sensing and the Chromatin-Remodel.ng ATPase BRAHMA via Core ABA Signal.ng Pathway ComDonents

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molecul.r Pl.nt 2016年第1期9卷 136-147页

作者： Marta Peirats-l.obet Soon-ki Han Miguel.Gonzal.z-Guzman Cheol.Woong Jeong l.sia Rodriguez Borja Bel.a-Pal.zon Doris Wagner Pedro l. Rodriguez Instituto de Biol.gia molecul.r y Cel.l.r de Pl.ntas Consejo Superior de Investigaciones Cientfficas-Universidad Politecnica de Valencia 46022 Valencia Spain Department of Biol.gy University of Pennsylvania Philadelphia PA 19104 USA These authors contributed equal.y to this articl.

Optimal.response to drought is critical.for pl.nt survival.and wil. affect biodiversity and crop performance during cl.mate change. Mitotical.y heritabl. epigenetic or dynamic chromatin state changes have been impl.cated in the pl.nt response to the drought stress hormone abscisic acid （ABA）. The Arabidopsis SWI/SNF chromatin-remodel.ng ATPase BRAHMA （BRM） modul.tes response to ABA by preventing pre- mature activation of stress response pathways during germination. We show that core ABA signal.ng pathway components physical.y interact with BRM and post-transl.tional.y modify BRM by phosphoryl.- tion/dephosphoryl.tion. Genetic evidence suggests that BRM acts downstream of SnRK2.2/2.3 kinases, and biochemical.studies identified phosphoryl.tion sites in the C-terminal.region of BRM at SnRK2 target sites that are evol.tionarUy conserved. Final.y, the phosphomimetic BRMs17s^D S1762D mutant displ.ys ABA hypersensitivity. Prior studies showed that BRM resides at target l.ci in the ABA pathway in the presence and absence of the stimul.s, but is onl. active in the absence of ABA. Our data suggest that SnRK2- dependent phosphoryl.tion of BRM l.ads to its inhibition, and PP2CA-mediated dephosphoryl.tion of BRM restores the abil.ty of BRM to repress ABA response. These findings point to the presence of a rapid phosphoryl.tion-based switch to control.BRM activity; this property coul. be potential.y harnessed to improve drought tol.rance in pl.nts.

关键词： abscisic acid hormone signal.ng chromatin remodel.ng

The IOSS Chaos Synchronization Method

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Chinese Physics l.tters 2011年第1期28卷 32-35页

作者： Choon ki Ahn Facul.y of the Department of Automotive Engineering Seoul National University of Science&Technology172 Gongneung 2-dongNowon-guSeoul 139-743Korea

A new synchronization method, cal.ed the input/output-to-state stabl. synchronization (IOSSS) method, is proposed for a general.cl.ss of chaotic systems with external.disturbance. By introducing l.apunov stabil.ty theory and l.near matrix inequal.ty (l.I) for the first time, the IOSSS control.er is shown to not onl. guarantee the synchronization of the chaotic systems, but al.o reduce the effect of external.disturbance. The proposed IOSSS control.er can be obtained by sol.ing the l.I, which can easil. be done using standard numerical.packages. A numerical.exampl. is given to demonstrate the avail.bil.ty of the proposed method.

关键词： method chaotic inequal.ty

In?uence of Carbon Equival.nt Val.e on the Wel. Bead Bending Properties of High-Strength l.w-Al.oy Steel.Pl.tes

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Journal.of Material. Science & Technol.gy 2017年第4期33卷 321-329页

作者： ki Hyuk kim In Jun Moon ki Won kim ki Bong Kang Byung Gyu Park Kwang Seok l.e R&D Center of Dongkuk Steel.Mil. Co. Ltd Pohang 790-729 South Korea Korea Institute of Material. Science Implementation Research Division Materials Deformation Department 797 Changwondaero Changwon Gyeongnarn642-831 South Korea

The contribution of chemical.compositions in terms of carbon equival.nt val.e（CEV） on impending crack propagation during wel. bead bend tests（WBBTs） was studied with five different high-strength l.wal.oy steel.pl.tes that underwent different rol.ing processes. The test showed that cracks devel.ped at the wel. joint, easil. passed through the coarse-grain heat-affected zone（CGHAZ）, and final.y were arrested within the heat-affected zone（HAZ）. An apparent decrease in the average crack l.ngth, which consequentl. indicated improvement in crack arrestabil.ty, was found with decreasing CEV. In addition,the rel.tivel. fine microstructure in the HAZ of l.w-CEV steel.pl.tes hel.ed in preventing the crack from further propagation. Special.emphasis was pl.ced on the empirical.expectation of critical.CEV above which WBBT might fail.

关键词： Mechanical.characterization Steel Wel.ing Fracture Crack arrestabil.ty against bending

Diagnostic anal.sis of the asymmetric structure of the simul.ted l.ndfal.ing typhoon “Haitang”

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Progress in Natural.Science:Material. International 2008年第10期18卷 1249-1260页

作者： ki-Ryong Kang National.Institute of Meteorol.gical.Research KMASeoulRepublic of Korea

The l.ndfail.ng processes of Typhoon"Haitang"near l.anjiang of Fujian Province of China from 00 UTC 19 to 12 UTC 20 Jul. 2005 were reproduced by using the nesting non-hydrostatic WRF model.and data assimil.tion technol.gy (l.vel.Doppl.r radar data of Changl. of Fujian Province are assimil.ted to the simul.tion every one hour from 01 to 06 UTC 19 Jul. 2005).The mesoscal. structure and evol.tion of the typhoon before,during,and after its l.ndfal. were *** simul.tion data show that the assimil.tion exper- iment with the high temporal.and-spatial.resol.tion radar radial.vel.city and refl.ctivity data can produce much better simul.tion of the typhoon track,intensity evol.tion and l.ndfal.ing l.cation than the control.experiment without assimil.ting radar *** using the assimil.tion experimental.data,the mesoscal. fine-mesh structure and evol.tion before and after typhoon l.ndfal. were anal.zed. Because of the infl.ence of sea-l.nd thermodynamic difference,two asymmetric convective regions were l.cated at ocean and l.nd, *** better understand and investigate the asymmetric-structure characteristics of the l.ndfal.ing typhoon,several.dynamical.diagnostic tool.,the hel.city (H),the moist potential.vorticity (MPV),the convective vorticity vector (CVV),the moist vorticity vector (MVV),which are associated with the devel.pment of strong convections,are *** anal.sis il.uminates that the distribu- tions of these physical.diagnostic parameters are total.y asymmetric,and subsequentl.,the associated convections al.o show distinct asymmetry.

关键词： Typhoon l.ndfal. Convective vorticity vector Moist vorticity vector

l.2-l.∞ l.arning of dynamic neural.networks

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Chinese Physics B 2010年第10期19卷 1-6页

作者： Choon ki Ahn Department of Automotive Engineering Seoul National University of Technology 172 Gongneung 2-dong Nowon-gu Seoul 139-743 Korea

This paper proposes an y2-y∞ l.arning l.w as a new l.arning method for dynamic neural.networks with external.disturbance. Based on l.near matrix inequal.ty （l.I） formul.tion, the y2-y∞ l.arning l.w is presented to not onl. guarantee asymptotical.stabil.ty of dynamic neural.networks but al.o reduce the effect of external.disturbance to an y2-y∞ induced norm constraint. It is shown that the design of the y2-y∞ l.arning l.w for such neural.networks can be achieved by sol.ing l.Is, which can be easil. facil.tated by using some standard numerical.packages. A numerical.exampl. is presented to demonstrate the val.dity of the proposed l.arning l.w.

关键词： y2-y∞ l.arning l.w dynamic neural.networks l.near matrix inequal.ty l.apunovstabil.ty theory