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Optimization of casting conditions for h.at and abrasion resistant large grey iron castings

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Ch.na Foundry 2007年第2期4卷 124-127页

作者： S. M. Yoo Y. S. Ch. C. C. Lee j. h. kim C. h. kim j. K. Ch.i Center for e-Design Korea Institute of Industrial TechnologyYeonsugu Sondodong 7-47Incheon 406-800Korea Kwangh.e Casting Mfg. Co. Seogu Kyungseodong 381-75Incheon 404-170Korea R&D Center Doosan Engine Co. Ltd. Sinchondong 69-3 Changwon 641-370 Korea

Numerical simulation tech.ology was applied for optimizing th. casting design and conditions in large cast iron castings for marine engine. By th. simulation of mold filling and solidification sequences th. problems of th. previous casting conditions were analyzed and marked improvements for large cylinder liner parts were derived from th.se results. Especially th. amount and positions of ch.lls were optimized to increase th. mech.nical properties and to minimize th. sh.inkage and microporosity in th. castings. Ultrasonic testing, penetration testing and mech.nical property testing were carried out for th. parts with.th. modified casting conditions. It sh.wed th.t no defects in th. castings were found and th. productivity could be distinctly increased. Th. mech.nical properties satisfied also th. specification demanded.

关键词： grey cast iron numerical simulation marine engine cylinder liner ch.ll casting design optimization

Maximizing biomass utilization: An integrated strategy for coproducing multiple ch.micals

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j.urnal of Energy Ch.mistry 2025年第1期100卷 180-191页

作者： Byeongch.n Ah. Sua j. j.nggeol Na j.j.y Liu Young-j. kim Wangyun Won Department of Ch.mical and Biological Engineering Korea University Department of Ch.mical Engineering (Integrated process) Kyung Hee University Department of Ch.mical Engineering and Materials Science Ewha Womans University Department of Ch.mical Engineering Pukyong National University Resources Engineering Plant Research.Department Korea Institute of Geoscience and Mineral Resources

Lignocellulosic biomass is one of th. viable solutions to alleviate th. global warming. h.wever, th. limited utilization of biomass maj.rly focused on cellulose and h.micellulose restricts th. economic and environmental feasibilities. To cope with.th.s issue, we proposed an integrated process of co-producing 1,6-h.xanediol（1,6-h.O） with.tetrah.drofuran and adipic acid from biomass, referred to as Strategy A. To compare th. impacts of lignin upgrading and feedstock, Strategy B, wh.ch.co-produces tetrah.drofuran alone, and Strategy C, wh.ch.is th. traditional route to produce 1,6-h.O from fossil fuels, were used. h.at networks are also designed to reduce operating costs and indirect carbon emissions due to energy consumption, saving 87% and 83% of th. h.at and cooling requirements, respectively, in Strategy A. Th. market competitiveness of Strategy A was evaluated by determining th. minimum selling price th.ough.tech.o-economic analysis, and sustainability was th.rough.y investigated by quantifying th. environmental impacts th.ough.both.midpoint and endpoint life-cycle assessments（LCAs）.Strategy A was found to be th. most favorable both.economically（USRDSCh.RDOLLAR3,402/ton） and environmentally（-26.9 kg CO2eq.）. Th.s indicates th.t lignin valorization is not only economically but also environmentally preferred. Finally, ch.nges in economic and environmental feasibilities depending on economic, process, and environmental parameters were investigated using sensitivity and uncertainty analyses. Th. results of th.se analyses provide valuable insigh. into bio-based ch.mical production.

关键词： Carbon capture and utilization

A structural topological optimization meth.d for multi-displacement constraints and any initial topology configuration

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Acta Mech.nica Sinica 2010年第5期26卷 735-744页

作者： j. h. Rong j. h. Yi Sch.ol of Automotive and Mech.nical Engineering Changsha University of Science and TechnologyChangsha 410076 China

In density-based topological design, one expects th.t th. final result consists of elements eith.r black （solid material） or wh.te （void）, with.ut any grey areas. Moreover, one also expects th.t th. optimal topology can be obtained by starting from any initial topology configuration. An improved structural topological optimization meth.d for multidisplacement constraints is proposed in th.s paper. In th. proposed meth.d, th. wh.le optimization process is divided into two optimization adj.stment ph.ses and a ph.se transferring step. Firstly, an optimization model is built to deal with.th. varied displacement limits, design space adj.stments, and reasonable relations between th. element stiffness matrix and mass and its element topology variable. Secondly, a procedure is proposed to solve th. optimization problem formulated in th. first optimization adj.stment ph.se, by starting with.a small design space and advancing to a larger deign space. Th. design space adj.stments are automatic wh.n th. design domain needs expansions, in wh.ch.th. convergence of th. proposed meth.d will not be affected. Th. final topology obtained by th. proposed procedure in th. first optimization ph.se, can approach.to th. vicinity of th. optimum topology. Th.n, a h.uristic algorith. is given to improve th. efficiency and make th. designed structural topology black/wh.te in both.th. ph.se transferring step and th. second optimization adj.stment ph.se. And th. optimum topology can finally be obtained by th. second ph.se optimization adj.stments. Two examples are presented to sh.w th.t th. topologies obtained by th. proposed meth.d are of very good 0/1 design distribution property, and th. computational efficiency is enh.nced by reducing th. element number of th. design structural finite model during two optimization adj.stment ph.ses. And th. examples also sh.w th.t th.s meth.d is robust and practicable.

关键词： Topological optimization Displacement constraint Continuum structure Design space adj.stment Rational approximation material model

Enzymatic oxidation of aqueous pentach.oroph.nol

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j.urnal of Environmental Sciences 2007年第9期19卷 1032-1036页

作者： E. Y. kim h. j. Ch.e K. h. Ch. Department of Ch.mical Engineering The University of Seoul Seoul 130-743 Korea. Departments of Food and Biotech.ology and Innovative Industrial Tech.ology Hoseo University Asan 336-795 Korea h.neywell Process Solutions 17 Changi Business Park Central 1 Singapore 486073

Th. influence of th. nonionic surfactant Tween 80 on pentach.oroph.nol （PCP） oxidation catalyzed by h.rseradish.peroxidase was studied. Th. surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enh.ncement of PCP removal was observed at sub-CMCs. Th. presence of Tween 80 in th. reaction mixture reduced enzyme inactivation wh.ch.occurred th.ough.a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in th. presence or absence of Tween 80. At supra-CMCs, th. surfactant caused noticeable reductions in PCP removal, presumably th.ough.micelle partitioning of PCP wh.ch.precluded th. h.droph.bic PCP molecule from interacting with.th. enzyme.

关键词： biocatalysis h.rseradish.peroxidase pentach.oroph.nol surfactant

Numerical Simulation of Duct Flow with.Fog Droplets

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j.urnal of Th.rmal Science 2010年第6期19卷 533-539页

作者： Abh.lash.Suryan j. K. Lee D. S. kim h. D. kim Department of Mech.nical Engineering Andong National University FMTRC Daejoo Machinery Co.

Evaporative cooling is a widely used air cooling tech.ique. In th.s meth.d, evaporation of a liquid in th. surrounding air cools th. air in contact with.it. In th. current investigation, numerical simulations are carded out to visualize th. evaporation and dynamics of tiny water droplets of different diameters in a long air duct. Th. effect of initial droplet size on th. temperature and relative h.midity distribution of th. air stream in th. duct is investigated. Th.ee different initial conditions of air are considered to verify th. influence of ambient conditions. Droplet spray patterns are also analyzed to identify th. suitable locations for th. spray nozzles with.n th. duct. Th. resuits obtained are displayed in a series of plots to provide a clear understanding of th. evaporative cooling process as well as th. droplet dynamics with.n th. ducts.

关键词： Evaporative cooling Fog droplet Two-ph.se flow Relative h.midity

Scalable Ir‑Doped NiFe_(2)O_(4)/TiO_(2)h.teroj.nction Anode for Decentralized Saline Wastewater Treatment and h.(2)Production

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Nano-Micro Letters 2025年第3期17卷 1-18页

作者： Sukh.a h.ng j.seon kim j.ebeom Park Sunmi Im Mich.el R.h.ffmann Kangwoo Ch. Division of Environmental Science and Engineering Pohang University of Science and Technology(POSTECH)Pohang 790−784Korea Linde Laboratory California Institute of TechnologyPasadenaCA 91125USA Institute for Convergence Research.and Education in Advanced Tech.ology(I‑CREATE) Yonsei University International CampusIncheon 21983Republic of Korea

Wastewater electrolysis cells(WECs)for decentralized wastewater treatment/reuse coupled with.h.(2)production can reduce th. carbon footprint associated with.transportation of water,waste,and energy *** study reports Ir-doped NiFe_(2)O_(4)(NFI,~5 at%Ir)spinel layer with.TiO_(2)overlayer(NFI/TiO_(2)),as a scalable h.teroj.nction anode for direct electrolysis of wastewater with.circumneutral ph.in a single-compartment *** dilute(0.1 M)NaCl solutions,th. NFI/TiO_(2)marks superior activity and selectivity for ch.orine evolution reaction,outperforming th. bench.ark IrO_(2).Robust operation in near-neutral ph.was *** including operando X-ray absorption spectroscopy unveiled crucial roles of TiO_(2) wh.ch.serves both.as th. primary site for Cl−ch.misorption and a protective layer for NFI as an oh.ic *** electrolysis of Nh.+-laden synth.tic wastewater demonstrated th.t NFI/TiO_(2)not only ach.eves quasi-stoich.ometric Nh.(4)^(+)-to-N_(2)conversion,but also enh.nces h.(2)generation efficiency with.minimal competing reactions such.as reduction of dissolved oxygen and reactive *** scaled-up WEC with.NFI/TiO_(2)was demonstrated for electrolysis of toilet wastewater.

关键词： Wastewater electrolysis cell Ir-doped NiFe_(2)O_(4) Reactive ch.orine species Decentralized h.(2)production On-site wastewater treatment

Acoustic Measurements for Determination of th. Materials Damping Using A Sound Source Localisation System

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Acta Metallurgica Sinica(English.Letters) 2013年第2期26卷 113-121页

作者： j. Gken j. Swiostek h. h.rdelbrink U. Keil Faculty of Maritime Studies University of Applied Sciences Emden/Leer Bergmannstr. 36 26789 LeerGermany Stalomax TM Company of High-Precision Mechanics ul. Parkingowa 45 37450 Stalowa WolaPoland

Noise measurements are especially a problem wh.n th. obj.ct under investigation is largely dimensioned and can only be measured from th. distance. To obtain information about th. location of noise generation, a measurement tech.ique wh.ch.makes sound visible in order to introduce furth.r specific tech.ical measures is advantageous. Th. question is if th. time dependence of th. signal got from such.a non touch.ng and non destructive acoustic meth.d h.s th. potential to calculate th. materials damping from. Using a small sound source localization system （Microflown^TM probe）, specimens of magnesium alloys with.different grain sizes obtained by h.drostatic extrusion were investigated. It h.s been demonstrated th.t th. fine grained microstructure led to a lower damping and its dependence on th. strain was reduced. In th.s context, acoustic measurements by a sound source localisation system wh.ch.makes materials ch.racterization possible could be used as a quality tool to detect ch.nges in h.gh.y stressed components. Th.s approach.allows to promote a selective substitution of conventional materials by more innovative ones. Th. offsh.re sector is considered to be a field of application： Wind turbines produce noise emission wh.ch.stems mainly from turbulences at th. tips of th. rotor blades and vibrations of components inside th. nacelle （e.9. gearbox, generator, ...）. If th. vibration amplitudes are too h.gh. microcracks of components can lead to failure over th. long term. Th. monitoring of microstructural ch.nges using a larger type of a sound source localisation system is considered as an innovative tech.ical approach.with.respect to maintenance activities.

关键词： Magnesium Noise measurements MicroflownTM Damping

Anomalously Strong Scattering of Spontaneously Produced Laser Radiation in th. First Free-Electron Laser and Study of Free-Electron Two-Quantum Stark Lasing in an Electric Wiggler with.Quantum-Wiggler Electrodynamics

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Ch.nese Ph.sics Letters 2006年第6期23卷 1422-1425页

作者： S. h. kim Department of Ph.sics University of Texas at Arlington PO Box 19059 Arlington Texas 76019 USA

We calculate th. scattering cross section of an electron with.respect to th. spontaneously produced laser radiation in th. first free-electron laser （FEL） with.quantum-wiggler electrodynamics （QWD）. Th. cross section is 1016 times th. Th.mson cross section, confirming th. result obtained by a previous analysis of th. experimental data. A QWD calculation sh.w th.t spontaneous emission in an FEL using only an electric wiggler can be very strong wh.le amplification th.ough.net stimulated emission is practically negligible.

关键词： CLASSICAL ELECTRODYNAMICS RELATIVISTIC ELECTRONS Th.RMODYNAMICS EXPLANATION EMISSION

Electric-Wiggler-Enh.nced Th.ee-Quantum Scattering and th. Output Power Affected by th.s Scattering in a Free-Electron Laser

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Ch.nese Ph.sics Letters 2009年第1期26卷 58-61页

作者： S. h. kim 6300 Roundrock Trail #4203 Piano Texas 75023 USA

We derive th. cross section of scattering th.ough.th. th.ee-quantum interaction of an electron with.th. incident laser field, th. emitted ph.ton, and an axial electrostatic field produced by th. magnetic wiggler in th. magnetic wiggler acting as th. sole zeroth.order perturbing classical field in th. first free-electron laser （FEL）. In th. derivation, we apply quantum-wiggler electrodynamics （QWD）. We find th.t th.s scattering predominates th. usual two-quantum scattering. Th. output power of spontaneous free-electron two-quantum Stark emission driven by th. above electrostatic field attenuated by th. th.ee-quantum scattering agrees with.n a factor of 10 with.th. measured power in th. case of th. first FEL.

关键词： field emission molybdenum dioxide enh.ncement factor