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Non-Local Analysis of Forming Limits of Ductile material Considering Void Growth

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Journal of materials Science & Technology 2003年第4期19卷 294-299页

作者： Youngsuk kim School of mechanical Engineering Kyungpook National University702-701DaeguSouth Korea

The current study performed a finite element analysis of the strain localization behavior of a voided ductile material using a non-local plasticity formulation in which the yield strength depends on both an equivalent plastic strain measurement (hardening parameter) and Laplacian equivalent. The introduction of gradient terms to the yield function was found to play an important role in simulating the strain localization behavior of the voided ductile material. The effect of the mesh size and characteristic length on the strain localization were also investigated. An FEm simulation based on the proposed non-local plasticity revealed that the load-strain curves of the voided ductile material subjected to plane strain tension converged to one curve, regardless of the mesh size. In addition, the results using non-local plasticity also exhibited that the dependence of the deformation behavior of the material on the mesh size was much less sensitive than that with classical local plasticity and could be successfully eliminated through the introduction of a large value for the characteristic length.

关键词： Non-local Characteristic length Vbid Damage growth Gradient-dependent plasticity Forming limit Strain localization

Acute and chronic toxicity of nickel to nitrifiers at different temperatures

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Journal of Environmental Sciences 2019年第8期31卷 169-178页

作者： Xiaoguang Liu mohammad m.I.Chowdhury masuduz Zaman mingu kim George Nakhla Department of Civil and Environmental Engineering University of Western Ontario Department of Chemical and Biochemical Engineering University of Western Ontario

This study investigated the acute nickel toxicity on nitrification of low ammonia synthetic wastewater at 10, 23, and 35°C. The nickel inhibition half-velocity constants(K_(I,Ni)) for ammonia oxidizing bacteria(AOB) and nitrite oxidizing bacteria(NOB) based on Ni/mLSS ratio at 10, 23, and 35°C were 5.4 and 5.6 mg Ni/g mLSS, 4.6 and 3.5 mg Ni/g mLSS, and 9.1 and 2.7 mg Ni/g mLSS, respectively. In addition, chronic toxicity of nickel to nitrification of low ammonia synthetic wastewater was investigated at 10°C in two sequencing batch reactors(SBRs). Long-term SBRs operation and short-term batch tests were comparable with respect to the extent of inhibition and corresponding Ni/mLSS ratio. The μ_(max), b, and K_o of AOB were 0.16 day^(-1), 0.098 day^(-1) and 2.08 mg O_2/L after long-term acclimatization to nickel of 1 mg/L at 10°C, high dissolved oxygen(DO)(7 mg/L) and long solids retention time(SRT) of 63–70 days. Acute nickel toxicity of nitrifying bacteria was completely reversible.

关键词： Nickel inhibition Temperature Nitrifying culture Activated sludge Toxicity

Variable selection-based SPC procedures for high-dimensional multistage processes

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Journal of Systems Engineering and Electronics 2019年第1期30卷 144-153页

作者： kim Sangahn Department of Business Analytics and Acturial Science Siena College

monitoring high-dimensional multistage processes becomes crucial to ensure the quality of the final product in modern industry environments. Few statistical process monitoring(SPC) approaches for monitoring and controlling quality in highdimensional multistage processes are studied. We propose a deviance residual-based multivariate exponentially weighted moving average(mEWmA) control chart with a variable selection procedure. We demonstrate that it outperforms the existing multivariate SPC charts in terms of out-of-control average run length(ARL) for the detection of process mean shift.

关键词： diagnosis procedure deviance residual fault identification model-based control chart multistage process monitoring variable selection.

mapping of ground motion amplifications for the Fraser River delta in Greater Vancouver, Canada

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Earthquake Engineering and Engineering Vibration 2019年第4期18卷 703-717页

作者： Byungmin kim Ulsan National Institute of Science and Technology

The Fraser River delta in Greater Vancouver, Canada consists of deep soft deposits of silts and clays, and it is well known that the deep soil deposits can amplify the low frequency contents of ground motions. This study aims to investigate the eff ects of deep soil deposits in the delta on ground motion amplifi cations by using thorough site response simulations that account for the full soil profi les and a suite of recorded ground motions that covers a wide range of intensity levels. Based on both equivalent-linear and nonlinear site response simulations, the eff ects of soil depth (represented by natural period of the soil, TS) on ground motion amplifi cations for various spectral periods are clearly demonstrated. The ground motion amplifi cation maps for various spectral periods and rock ground motion intensity levels are also generated to be used in the regional seismic hazard assessment for infrastructure. It is found that ground motions for long periods are substantially amplifi ed in the center of the delta, while those for short periods are de-amplifi ed when input rock motions are large.

关键词： Fraser River delta ground motion amplifi cation deep soil deposits site response analysis basin depth

Suggestion of maintenance Criteria for Electric Railroad Facilities Based on Fuzzy TOPSIS

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Computers, materials & Continua 2022年第3期70卷 5453-5466页

作者： Sunwoo Hwang Joouk kim Hagseoung kim Hyungchul kim Youngmin kim Innovative Transportation and Logistics Research Center Korea Railroad Research InstituteUiwang16105Korea Smart Electrical&Signaling Division Korea Railroad Research InstituteUiwang16105Korea Department of Systems Engineering Ajou UniversitySuwon16499Korea

This paper is on the suggestion of maintenance items for electric railway facility *** the recent increase in the use of electric locomotives,the utilization and importance of railroad electrical facility systems are also increasing,but the railroad electrical facility system in Korea is rapidly *** solve this problem,various methodologies are applied to ensure operational reliability and stability for railroad electrical facility systems,but there is a lack of detailed evaluation criteria for railroad electrical facility system ***,maintenance items must be selected in a scientific and systematic ***,railroad electrical facility systems are selected for *** Structurematrix(DSm)is utilized to establish considerations tailored to the maintenance characteristics,and the Fuzzy-TOPSIS methodology is utilized for determining the maintenance detail evaluation item baseline weights,a multi-criteria decision-making *** show that degradation,insulation items have the highest weight of 14.63%,and capacity items have the lowest weight of 5.34%.The results of this may be contributed to the underlying research in carrying out maintenance activities to ensure the reliability and safety of railroad electrical facility systems.

关键词： Electrical facility system railroad maintenance fuzzy method

Utilization of the superior properties of highly mesoporous PVP modified NiCo_2O_4 with accessible 3D nanostructure and flower-like morphology towards electrochemical methanol oxidation reaction

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Journal of Energy Chemistry 2019年第2期28卷 136-146页

作者： Gracita m.Tomboc medhen W.Abebe Anteneh F.Baye Hern kim Department of Energy Science and Technology Smart Living Innovation Technology CenterMyongji University

Up to this date,researchers are still facing difficulties to expand the technology of direct methanol fuel cells(DmFCs) because of the high overpotential required to oxidize the methanol and its relatively poor performance due to CO poisoning of the leading-high cost anode *** line with this,we have successfully modified the morphological structure and composition of low cost cobalt based-metal oxides,mCo_2O_4(m = Zn and Ni),with the simple and noble use of polyvinyl pyrrolidone(PVP) as growth modifier and surface stabilizer during the synthesis of nanoparticles in our previous reports,which shown high electrocatalytic activity and strong *** to the good performance of our PVP modified mCo_2O_4 towards pseudocapacitor and oxygen evolution reaction applications,we decided to extend our research study to methanol oxidation ***,PVP modified Ni Co_2O_4 electrode directly grown on nickel foam substrate via a simple hydrothermal process exhibited better performance compared with PVP modified ZnCo_2O_4 and NiCo_2O_4 without *** had obtained a remarkably low onset potential of 0.285 V and high current density of 280 m A cm^(-2),and shown great stability and high poison tolerance during a continuous CV cycling and Chronoamperometry test,which attained high efficiency of 86.86%and 98.52%,*** positive results of PVP modified Ni Co_2O_4 electrode towards mOR might be attributed to its hierarchical 3 D nanostructures with highly mesoporous surface and large surface area which may have provided numerous electroactive sites,and the exceptional corrosion stability of Ni Co_2O_4 electrode in alkaline solution.

关键词： NiCo2O4 3D nanostructure Electrochemical methanol oxidation Current density

Engineered 3D liver-tissue model with minispheroids formed by a bioprinting process supported with in situ electrical stimulation

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Bioactive materials 2024年第5期35卷 382-400页

作者： WonJin kim GeunHyung kim Department of Precision medicine Sungkyunkwan University School of Medicine(SKKU-SOM)Suwon16419Republic of Korea Institute of Quantum Biophysics Department of BiophysicsSungkyunkwan UniversitySuwon16419Republic of Korea Biomedical Institute for Convergence at SKKU(BICS) Sungkyunkwan UniversitySuwon16419Republic of Korea

Three-dimensional(3D)bioprinting,an effective technique for building cell-laden structures providing native extracellular matrix environments,presents challenges,including inadequate cellular *** address these issues,cell spheroids offer a promising solution for improving their biological ***,minispheroids with 50-100μm diameters exhibit enhanced cellular *** propose a one-step minispheroid-forming bioprinting process incorporating electrical stimulation(E-mS-printing).By stimulating the cells,minispheroids with controlled diameters were generated by manipulating the bioink viscosity and stimulation *** validate its feasibility,E-mS-printing process was applied to fabricate an engineered liver model designed to mimic the hepatic lobule unit.E-mS-printing was employed to print the hepatocyte region,followed by bioprinting the central vein using a core-shell *** resulting constructs displayed native liver-mimetic structures containing minispheroids,which facilitated improved hepatic cell maturation,functional attributes,and vessel *** results demonstrate a new potential 3D liver model that can replicate native liver tissues.

关键词： Bioprinting In situ electric field minispheroids In vitro liver-tissue model Hepatic lobule

Wave solutions and numerical validation for the coupled reaction-advection-diffusion dynamical model in a porous medium

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Communications in Theoretical Physics 2022年第12期74卷 9-20页

作者： Ali m mubaraki Hwajoon kim R I Nuruddeen Urooj Akram Yasir Akbar Department of mathematics and Statistics Collage of ScienceTaif UniversityP O Box 11099Taif 21944Saudi Arabia Kyungdong University YangjuRepublic of Korea Department of mathematics Faculty of ScienceFederal University DutseP O Box 7156 DutseJigawa StateNigeria Department of mathematics COMSATS University IslamabadLahorePakistan Department of mathematics COMSATS University Islamabad44000 IslamabadPakistan

The current study examines the special class of a generalized reaction-advection-diffusion dynamical model that is called the system of coupled Burger’s *** system plays a vital role in the essential areas of physics,including fluid dynamics and ***,two promising analytical integration schemes are employed for the study;in addition to the deployment of an efficient variant of the eminent Adomian decomposition *** sets of analytical wave solutions are revealed,including exponential,periodic,and dark-singular wave solutions;while an amazed rapidly convergent approximate solution is acquired on the other *** the end,certain graphical illustrations and tables are provided to support the reported analytical and numerical *** doubt,the present study is set to bridge the existing gap between the analytical and numerical approaches with regard to the solution validity of various models of mathematical physics.

关键词： reaction-advection-diffusion model Burger’s equations mETEm Km NLDm

Three metabolites from an entomopathogenic bacterium, Xenorhabdus nematophila, inhibit larval development of Spodoptera exigua （Lepidoptera： Noctuidae） by inhibiting a digestive enzyme, phospholipase A2

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Insect Science 2011年第3期18卷 282-288页

作者： Jaehyun kim Yonggyun kim Department of Bioresource Sciences Andong National University Andong Korea

An entomopathogenic bacterium, Xenorhabdus nematophila, has been known to induce significant immunosuppression of target insects by inhibiting immune-associated phospholipase A2 （PLA2）, which subsequently shuts down biosynthesis of eicosanoids that are critical in immune mediation in insects. Some metabolites originated from the bacterial culture broth have been identified and include benzylideneacetone, proline-tyrosine and acetylated phenylalanine-glycine-valine, which are known to inhibit enzyme activity of PLA2 extracted from hemocyte and fat body. This study tested their effects on digestive PLA2 of the beet armyworm, Spodoptera exigua. Young larvae fed different concentrations of the three metabolites resulted in significant adverse effects on larval development even at doses below 100 #g/mL. In particular, they induced significant reduction in digestive efficiency of ingested food. All three metabolites significantly inhibited catalytic activity of digestive PLA2 extracted from midgut lumen of the fifth instar larvae at a low micromolar range. These results suggest that the inhibitory activities of the three bacterial metabolites on digestive PLA2 of S. exigua midgut may explain some of their oral toxic effects.

关键词： digestion midgut phospholipase A2 Spodoptera exigua Xenorhabdus nematophila