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Effects of Heterogeneous Condensation on the Transonic Flow Fields on a Bump Model

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Journal of Thermal Science 2005年第1期14卷 34-40页

作者： Masanori TANAKA Shigeru MATSUO Toshiaki SETOGUCHI Heuy-dong kim Department of Mechanical Engineering Saga University 1 Honjo-machiSaga shiSaga 840-8502JapanDepartment of Mechanical Engineering Saga University1 Honjo-machiSaga shiSaga 840-8502JapanDepartment of Mechanical Engineering Saga University1 Honjo-machiSaga shiSaga 840-8502JapanSchool of Mechanical Engineering College of Natural ScienceAndong National University388Song Cheon DongAndongKyung PookKorea

In the present study, effect of the heterogeneous condensation on the characteristics of shock wave generated on the bump model in the transonic flow field was investigated numerically. As a result, it was found that, for the flow field with steady adiabatic shock wave on the bump model, the condensation with heterogeneous nucleation has a strong effect on the whole flow field, and it reduced the strength of the shock. Furthermore, the total pressure loss was dependent on the concentration of the solid particles per unit volume.

关键词： compressible flow transonic flow heterogeneous condensation simulation.

Numerical Study of Shock Tube Flows with Homogeneous and Heterogeneous Condensations in Rarefaction Wave

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Journal of Thermal Science 2010年第4期19卷 326-331页

作者： Junji Nagao Shigeru Matsuo Toshiaki Setoguchi Heuy dong kim Graduate School of Science & Engineering Saga University1 Honjo-machiSaga-shiSaga840-8502Japan Department of Advanced Technology Fusion Saga University1 Honjo-machiSaga-shiSaga 840-8502Japan Institute of Ocean Energy Saga University1 Honjo-machiSaga-shiSaga 840-8502Japan. School of Mechanical Engineering Andong National University388Songcheon-dongAndong 760-749Korea

Shock tubes are devices in which the state of a gas is changed suddenly from one uniform state to another by the passage of shock and expansion *** the theory of ideal shock tube flow,it is customarily assumed that the unsteady expansion and shock waves generated by diaphragm rupture are a perfectly centered plane ***, such waves are generally not centered,or may not even by plane in *** the present research,the time-dependent behavior of homogeneous and heterogeneous condensation of moist air in the shock tube is investigated by using a computational fluid dynamics ***,the numerical and experimental studies were carried out in order to investigate the effect of the diaphragm rupture process on the flow characteristics of expansion and shock waves generated near the diaphragm.

关键词： shock tube homogeneous condensation heterogeneous condensation diaphragm rupture

Supersonic Cavity Flows over Concave and Convex Walls

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Journal of Thermal Science 2016年第2期25卷 145-152页

作者： A Ran Ye Rajarshi Das Toshiaki Setoguchi Heuy dong kim Department of Mechanical Engineering Andong National University Institute of Ocean Engineering Saga University

Supersonic cavity flows are characterized by compression and expansion waves, shear layer, and oscillations inside the cavity. For decades, investigations into cavity flows have been conducted, mostly with flows at zero pressure gradient entering the cavity in straight walls. Since cavity flows on curved walls exert centrifugal force, the features of these flows are likely to differ from those of straight wall flows. The aim of the present work is to study the flow physics of a cavity that is cut out on a curved wall. Steady and unsteady numerical simulations were carried out for supersonic flow through curved channels over the cavity with L/H = 1. A straight channel flow was also analyzed which serves as the base model. The velocity gradient along the width of the channel was observed to increase with increasing the channel curvature for both concave and convex channels. The pressure on the cavity floor increases with the increase in channel curvature for concave channels and decreases for convex channels. Moreover, unsteady flow characteristics are more dependent on channel curvature under supersonic free stream conditions.

关键词： Cavity flow Supersonic Flow Compressible Flow Unsteady flow Pressure Oscillation

Optimization of post-warranty sequential inspection for second-hand products

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Journal of Systems Engineering and Electronics 2017年第4期28卷 793-800页

作者： Dae-Kyung kim Jae-Hak Lim dong Ho Park Department of Statistics Chonbuk National University Department of Management & Accounting Hanbat National University Industry Academic Cooperation Foundation Hallym University

This paper considers an optimal sequential inspection schedule for a second-hand product after that the free nonrenewable warranty is expired. The length of warranty is prespecified and during the warranty period, the product is minimally repaired by the dealer when it fails. Following the expiration of the non-renewing warranty, the product is inspected and upgraded sequentially a fixed number of times at the expenses of the *** each inspection, the failure rate of the product is reduced proportionally so that the product is upgraded. The product is assumed to deteriorate as it ages and the replacement of the product occurs when a fixed number of inspections are rendered. In addition,the intervals between two successive inspections are assumed to decrease monotonically. The main objective of this paper is to determine the optimal improvement level to upgrade the product at each inspection so that the expected maintenance cost during the life cycle of the product is minimized from the perspective of the customer. Under the given cost structures, we derive an explicit formula to obtain the expected maintenance cost incurred during the life cycle of the product and discuss the method to find the optimal level of the improvement analytically in case the failure times follow the Weibull distribution. Numerical results are analyzed to observe the impact of relevant parameters on the optimal solution.

关键词： second-hand product sequential inspection upgrade action life cycle of the product expected maintenance cost free non-renewable warranty

Caulerpa okamurae extract attenuates inflammatory interaction,regulates glucose metabolism and increases insulin sensitivity in 3T3-L1 adipocytes and RAW 264.7 macrophages

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Journal of Integrative Medicine 2020年第3期18卷 253-264页

作者： Bikash Manandhar Hyun Jung kim dong Young Rhyu Department of Oriental Medicine Resources and Institute of Korean Herbal Medicine Industry Mokpo National UniversityJeonnam 58554South Korea College of Pharmacy Mokpo National UniversityJeonnam 58554South Korea

Objective: To examine whether Caulerpa okamurae ethanolic extract(COE) could inhibit obesitymediated inflammation, improve glucose metabolism and increase insulin sensitivity, using in vitro cell models of RAW 264.7 macrophages and 3 T3-L1 ***: We cocultured 3 T3-L1 adipocytes in direct contact with lipopolysaccharide-stimulated RAW264.7 macrophages and induced insulin resistance in 3 T3-L1 adipocytes with tumor necrosis factor-a(TNF-a) in the presence or absence of 250 mg/m L of COE. We investigated various markers of inflammation, glucose regulation and insulin sensitivity in these models using Griess reagent to measure nitric oxide(NO) production, 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxyglucose to measure glucose uptake, Western blot analysis to quantify protein expression and reverse transcriptasepolymerase chain reaction to evaluate m RNA ***: We found that COE(250 mg/m L) significantly inhibited the lipopolysaccharide-induced inflammatory response in RAW 264.7 macrophages by downregulating NO production, nitric oxide synthase 2 expression and nuclear translocation of nuclear factor-j B. COE also showed similar anti-inflammatory activity in coculture, along with decreased TNF-a, interleukin-6 and monocyte chemoattractant protein m RNA expression. In addition, COE also improved glucose uptake in coculture by upregulating glucose transporter-4(GLUT-4) and adiponectin and reducing serine phosphorylation of insulin receptor substrate-1(IRS1). In the TNF-a-induced insulin resistance model of 3 T3-L1 adipocytes, COE significantly improved both basal and insulin-stimulated glucose uptake, accompanied by phosphorylation of IRS1 at tyrosine 632, phospho-50 adenosine monophosphate-activated protein kinase a and glycogen synthase kinase-3 b(Ser9) as well as upregulation of ***: Together, these findings suggest that COE has potential to treat or prevent obesity-induced metabolic disorders.

关键词： Caulerpa okamurae RAW 264.7 macrophages 3T3-L1 adipocytes Coculture Metabolic disorder

Effect of Nozzle Geometry on the Flow Characteristics of Spiral Flow Generated through an Annular Slit

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Journal of Thermal Science 2007年第2期16卷 149-154页

作者： Shigeru MATSUO Tae-Hun kim Toshiaki SETOGUCHI Heuy dong kim Yeon-Won LEE Department of Mechanical Engineering Saga University1Honjo-machiSaga-shiSaga 840-8502Japan Graduate school of Science and Technology Saga University1Honjo-machiSaga shiSaga 840-8502Japan School of Mechanical Engineering Andong National University388Songchun-dongAndong 760749Korea School of Mechanical Engineering College of EngineeringPukyong National UniversitySan 100Young-Dang DongBusanKorea

In comparison with previous researches of swirling flow, spiral flow generated in the spiral nozzle has some different flow characteristics. It does not need a forced tangential momentum to generate its velocity and has some different merits from the swirling flow such as long potential core and low tangential velocity. In this study, the effect of nozzle geometry on the flow characteristics in spiral nozzle was investigated by experiment and computation. As a result, the flow characteristics obtained by experiment has a satisfactory agreement with computational results, quantitatively and qualitatively.

关键词： nozzle flow characteristics momentum numerical simulation

Theoretical and Computational Analyses of LNG Evaporator

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Journal of Thermal Science 2017年第2期26卷 132-137页

作者： Palani Kumar Chidambaram Yang Myung Jo Heuy dong kim FMTRC Daejoo Machinery Co Ltd Department Mechanical Engineering Andong National University

Theoretical and numerical analysis on the fluid flow and heat transfer inside a LNG evaporator is conducted in this work. Methane is used instead of LNG as the operating fluid. This is because; methane constitutes over 80% of natural gas. The analytical calculations are performed using simple mass and energy balance equations. The analytical calculations are made to assess the pressure and temperature variations in the steam tube. Multiphase numerical simulations are performed by solving the governing equations(basic flow equations of continuity, momentum and energy equations) in a portion of the evaporator domain consisting of a single steam pipe. The flow equations are solved along with equations of species transport. Multiphase modeling is incorporated using VOF method. Liquid methane is the primary phase. It vaporizes into the secondary phase gaseous methane. Steam is another secondary phase which flows through the heating coils. Turbulence is modeled by a two equation turbulence model. Both the theoretical and numerical predictions are seen to match well with each other. Further parametric studies are planned based on the current research.

关键词： LNG Evaporator Analytical Calculation Numerical Simulation

Rotation characteristic and granular temperature analysis in a bubbling fluidized bed of binary particles

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Particuology 2015年第1期13卷 76-88页

作者： Tianyu Wang Yurong He Shengnan Yan dong Rip kim Department of Power Engineering Harbin Institute of Technology Department of Mechanical Engineering Hanyang University

In this work, a discrete particle model （DPM） was applied to investigate the dynamic characteristics in a gas-solid bubbling fluidized bed of binary solid particles. The solid phase was simulated by the hard- sphere discrete particle model. The large eddy simulation （LES） method was used to simulate the gas phase. To improve the accuracy of the simulation, an improved sub-grid scale （SGS） model in the LES method was also applied. The mutative Smagorinsky constant case was compared with the previously published experimental data. The simulation by the mutative Smagorinsky constant model exhibited better agreement with the experimental data than that by the common invariant Smagorinsky constant model. Various restitution coefficients and different compositions of binary solids were investigated to determine their influences on the rotation characteristics and granular temperatures of the particles. The particle translational and rotational characteristic distributions were related to certain simulation parameters.

关键词： Smagorinsky constant Rotational characteristics Binary mixture particles Large eddy simulation Discrete hard sphere mode

Passivation engineering via silica‐encapsulated quantum dots for highly sensitive photodetection

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Carbon Energy 2023年第9期5卷 49-62页

作者： Ji Yun Chun Byung Gi kim Jin Young kim Woongsik Jang dong Hwan Wang School of Integrative Engineering Chung‐Ang UniversitySeoulRepublic of Korea

Organometal halide perovskites are promising semiconducting materials for photodetectors because of their favorable optoelectrical *** nanoscale perovskite materials such as quantum dots(QDs)show novel behavior,they have intrinsic stability *** this study,an effectively silane barrier-capped quantum dot(QD@APDEMS)is thinly applied onto a bulk perovskite photosensitive layer for use in ***@APDEMS is synthesized with a silane ligand with hydrophobic CH_(3)-terminal groups,resulting in excellent dispersibility and durability to enable effective *** introduction of the QD@APDEMS layer results in the formation of a lowdefect perovskite film with enlarged *** is attributed to the grain boundary interconnection effect via interaction between the functional groups of QD@APDEMS and uncoordinated Pb^(2+)in grain *** passivating the grain boundaries,where various trap sites are distributed,hole chargecarrier injection and shunt leakage can be ***,from the energy point of view,the deep highest occupied molecular orbital(HOMO)level of QD@APDEMS can work as a hole charge injection *** charge dynamics(generation,transfer,and recombination properties)and reduced trap density of QD@APDEMS are *** this perovskite film is used in a photodetector,the device performance(especially the detectivity)stands out among existing perovskites evaluated for energy sensing device applications.

关键词： grain boundary passivation perovskite quantum dots photodetectors photosensitive layers trap