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Numerical Visualization of Air Intake Induced by Free Surface Vortex

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Journal of Thermal Science 2017年第6期26卷 540-544页

作者： Young Kyu Park Mohan Kumar Dey Yoon Hwan Choi yeon won lee Research Institute of Industrial Science & Technology Pukyong National University Busan Korea Interdisciplinary Program of Biomedical Mechanical and Electrical Engineering Pukyong National University Busan Korea Department of Mechanical Design Engineering Pukyong National University Busan Korea

Free surface vortex control is vital in a pump sump system because the air absorbed by free surface vortex induc- es noise, vibration, and cavitation corrosion on the pumping system. In this study, the change of free surface vor- tex and air absorption in a pump intake has been investigated by the Volume of Fraction （VOF） method with steady multiphase flow model in order to represent the behavior of the free surface vortex exactly. The homoge- neous free surface model is used to apply interactions of air and water. The results show that air intake by the free surface vortex motion can be visualized using the iso-surface of air volume fraction. The vortices make an air column from the free surface to the pump intake. Also, it was found that the flee surface vortex can be controlled by installing curtain walls.

关键词： free surface vortex numerical visualization curtain wall air intake

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

Temperature Distribution and Thermal Stresses in Various Conditions of Moving Heating Source during Line Heating Process

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Journal of Thermal Science 2012年第1期21卷 82-87页

作者： Yoon Hwan Choi yeon won lee Kwang Choi Deog Hee Doh Kyoung Joon Kim Department of Mechanical and Automotive Engineering Pukyong National University Steel Structure Research Division Research Institute of Industrial Science & Technology Division of Mechanical and information Engineering Korea Maritime University

Line heating method is widely used to manufacture curved surfaces in ship building. The main factors governing the quality of the manufactured products are the moving velocity of the heating source, heating strength, and heating ways. In this study, the temperature distributions of the heated plate were investigated with the condition that the line heating process was automatic. The temperature variations were also investigated with the changes of those three variables. The numerical results showed that the peak temperature decreased as the moving velocity of the heating source increased. It also revealed that the peak temperatures changed linearly with the changes of the heating source.

关键词： Moving heat source Line heating Thermal stress Residual deformation Conductive heat transfer

Performance Analyses for a Cyclone Type Filter

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Journal of Thermal Science 2015年第3期24卷 290-294页

作者： Hyoung-June Kim Masahiro Takei Hyun Jin lee yeon won lee Yoon Hwan Choi Deog-Hee Doh School of Mechanical Engineering Artificial Science Division Chiba University Division of Mech. and Energy Systems Eng. Korea Maritime University Dept. of Mechanical and Automotive Engineering Pukyong National University

Flow characteristics inside a cyclone filter were investigated by the use of computational fluid dynamics(CFD). For computations, SST model was adopted. Parametric study was carried out considering the filtering performance. Revolution speeds were changed from 100 to 550 with 50 increments. A skirt is the driving source for cyclone operation. The influence of several design factors, such as the skirt length, the skirt gap and the return length to filtering performance was investigated under the particle diameter 100μm of debris material(Al, s.g.=2.7). The filtering performance was also investigated with the skirt length 28 mm changing the debris diameters from 1μm to 50μm. The flow rate of the working fluid was maintained at 0.55kg/s. It has been verified that the most influential factors to the filtering efficiencies was the skirt gap between the cyclone generator and the cyclone vessel.

关键词： CFD cyclone filter design factors filtering performances

Heat Transfer Enhancement of Cu-H<sub>2</sub>O Nanofluid with Internal Heat Generation Using LBM

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Open Journal of Fluid Dynamics 2013年第2期3卷 92-99页

作者： Mohammad Abu Taher yeon won lee Heuy Dong Kim School of Mechanical Engineering Andong National University Andong South Korea School of Mechanical Engineering Pukyong National University Busan South Korea

Fluid flow and heat transfer analysis of Cu-H2O nanofluid in a square cavity using a Thermal Lattice Boltzmann Method (TLBM) have been studied in the present work. The LBM has built up on the D2Q9 model and the single relaxation time method called the Lattice-BGK (Bhatnagar-Gross-Krook) model. The effect of suspended nanoparticles on the fluid flow and heat transfer analysis have been investigated for different non dimensional parameters such as particle volume fraction (φ) and particle diameters (dp) in presence of internal heat generation (q) of nanoparticles. It is seen that flow behaviors and the average rate of heat transfer in terms of the Nusselt number (Nu) as well as the thermal conductivity of nanofluid are effectively changed with the different controlling parameters such as particle volume fraction (2% ≤ φ ≤ 10%), particle diameter (dp = 5 nm to 40 nm) with fixed Rayleigh number, Ra = 105. The present results of the analysis are compared with the previous experimental and numerical results for both pure and nanofluid and it is seen that the agreement is good indeed among the results.

关键词： Nanofluid Lattice-Boltzmann Volume Fractions Particle Diameter Heat Generation

Efficient photovoltaic effect in graphene/h-BN/silicon heterostructure self-powered photodetector

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Nano Research 2021年第6期14卷 1967-1972页

作者： Ui yeon won Boo Heung lee Young Rae Kim won Tae Kang Ilmin lee Ji Eun Kim Young Hee lee Woo Jong Yu Department of Electrical and Computer Engineering Sungkyunkwan UniversitySuwon16419Republic of Korea Center for Integrated Nanostructure Physics Institute for Basic Science(IBS)Suwon16419Republic of Korea

Graphene(Gr)/Si-based optoelectronic devices have attracted a lot of academic attention due to the simpler fabrication processes,low costs,and higher performance of their two-dimensional(2D)/three-dimensional(3D)hybrid interfaces in Schottky junction that promotes electron-hole ***,due to the built-in potential of Gr/Si as a photodetector,the Iph/Idark ratio is often hindered near zero-bias at relatively low illumination *** is a major drawback in self-powered *** this study,we have demonstrated a self-powered van der Waals heterostructure photodetector in the visible range using a Gr/hexagonal boron nitride(h-BN)/Si structure and clarified that the thin h-BN insertion can engineer asymmetric carrier transport and avoid interlayer coupling at the *** dark current was able to be suppressed by inserting an h-BN insulator layer,while maintaining the photocurrent with minimal decrease at near *** a result,the normalized photocurrent-to-dark ratio(NPDR)is improved more than 104 ***,both Iph/Idark ratio and detectivity,increase by more than 104 times at−0.03 V drain *** proposed Gr/h-BN/Si heterostructure is able to contribute to the introduction of next-generation photodetectors and photovoltaic devices based on graphene or silicon.

关键词： graphene hexagonal boron nitride van der Waals heterostructure self-powered Research

Treatment of syringomyelia using uncultured umbilical cord mesenchymal stem cells: A case report and review of literature

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World Journal of Stem Cells 2022年第4期14卷 303-309页

作者： Hyunjun Ahn Sang yeon lee won-Ju Jung Kye-Ho lee Stem Cell Treatment and Research Institute(STRI) bio Beauty and Health Company(bBHC)Seoul 04420South Korea Stem Cell Treatment 97.7 Beauty and Health ClinicSeoul 04420South Korea

BACKGROUND Syringomyelia is a disease caused by the formation of a cavity inside the spinal cord and is accompanied by such symptoms as pain,paresthesia,and urination and defecation disorders,and in severe cases causes various ***,there are only surgical methods for the treatment of syringomyelia,but these methods carry the possibility of failure,recurrence,and side *** SUMMARY The patient was a 59-year-old woman who suffered from pain due to *** treatment,the patient received transplant of uncultured umbilical cord-derived mesenchymal stem *** intended,the patient's pain was relieved after ***,an additional benefit was found in that the size of the cavity also *** 2 years from the last treatment,the patient's cavity had almost completely disappeared and her syringomyelia was deemed *** Using uncultured umbilical cord-derived mesenchymal stem cells may be a new treatment alternative for syringomyelia.

关键词： Syringomyelia Umbilical cord mesenchymal stem cells Cell therapy Allogenic stem cells Chiari malformations Case report

Treatment of acute ischemic stroke by minimally manipulated umbilical cord-derived mesenchymal stem cells transplantation:A case report

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World Journal of Stem Cells 2021年第8期13卷 1151-1159页

作者： Hyunjun Ahn Sang yeon lee won Ju Jung Kye-Ho lee bio Beauty&Health Company(bBHC)-Stem Cell Treatment&Research Institute(STRI) Seoul 04420South Korea 97.7 Beauty&Health(B&H)Clinics Seoul 04420South Korea

BACKGROUND Stroke is one of the major causes of disability and death *** treatments for stroke exist,but existing treatment methods have limitations such as difficulty in the regeneration of damaged neuronal cells of the ***,mesenchymal stem cells(MSCs)have been studied as a therapeutic alternative for stroke,and various preclinical and case studies have been *** SUMMARY A 55-year-old man suffered an acute stroke,causing paralysis in the left upper and lower *** intravenously transplanted the minimally manipulated human umbilical cord-derived MSCs(MM-UC-MSCs)twice with an 8-d *** 65 wk after transplantation,the patient returned to his previous occupation as a veterinarian with no adverse *** MM-UC-MSCs transplantation potentially treats patients who suffer from acute ischemic stroke.

关键词： Acute ischemic stroke Behavioral disorder Umbilical cord-derived mesenchymal stem cells Allogenic Cell therapy Minimal manipulation Case report

Alopecia treatment using minimally manipulated human umbilical cord-derived mesenchymal stem cells:Three case reports and review of literature

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World Journal of Clinical Cases 2021年第15期9卷 3741-3751页

作者： Hyunjun Ahn Sang yeon lee won Ju Jung Kye-Ho lee bio Beauty&Health Company(bBHC)-Stem Cell Treatment&Research Institute(STRI) Seoul 04420South Korea Department of Functional Genomics University of Science and Technology KRIBB SchoolDeajeon 34113South Korea 97.7 Beauty&Health(B&H)Clinics Seoul 04420South Korea

BACKGROUND Alopecia areata(AA)is a common autoimmune disease characterized by hair *** appears in extensive forms,such as progressive and diffusing hair loss(diffuse AA),a total loss of scalp hair(alopecia totalis),and complete loss of hair over the entire body(alopecia universalis).Recently,mesenchymal stem cells(MSCs)have been identified as a therapeutic alternative for autoimmune *** this reason,preclinical and case studies of AA and related diseases using MSCs have been *** SUMMARY Case 1:A 55-year-old woman suffered from AA in two areas of the *** was given 15 rounds of minimally manipulated umbilical cord-MSCs(MM-UC-MSCs)over 6 *** AA gradually improved 3 mo after the first *** patient was cured,and AA did not *** 2:A 30-year-old woman,with history of local steroid hormone injections,suffered from AA in one area on the *** was given two rounds of MM-UC-MSCs over 1 *** AA immediately improved after the first *** patient was cured,and AA did not *** 3:A 20-year-old woman,who was diagnosed with alopecia universalis at the age of 12,was given 14 rounds of MM-UC-MSCs over 12 *** hair began to grow about 3 mo after the first *** patient was cured,and alopecia universalis did not *** MM-UC-MSC transplantation potentially treats patients who suffer from AA and related diseases.

关键词： Alopecia areata Umbilical cord-derived mesenchymal stem cells Allogenic Cell therapy Minimal manipulation Case report