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Neural Regeneration Research 2025年第1期20卷 195-196页

作者： hyun sung Department of Neurology Johns Hopkins University School of MedicineBaltimoreMDUSA Medical Research Institute and Department of PharmacologyPusan National University School of MedicineYangsanRepublic of Korea

Neurons are highly polarized,morphologically asymmetric,and functionally compartmentalized cells that contain long axons extending from the cell *** this reason,their maintenance relies on spatiotemporal regulation of organelle distribution between the somatodendritic and axonal *** some organelles,such as mitochondria and smooth endoplasmic reticulum,are widely distributed throughout the neuron,others are segregated to either the somatodendritic or axonal *** example,Golgi outposts and acidified lysosomes are predominantly present in the somatodendritic domain and rarely distributed along the axon,whereas newly formed autophagosomes and synaptic vesicles are mainly distributed in the distal axon(Britt et al.,2016).

关键词： organelle regulation distribution

The Heart Disorders with Survey Study in Oriental Medicine: Using the Magnetocardiography (MCG)

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Flow Characteristics in Compact Thermal Spray Coating Systems with Minimum Length Nozzle

第三届国际传统医药大会

作者： Sun Mi Choi Yeon Hee Ryu Jin Suk Moon Joung Yeol Kim Kyung Mo Park Young Huh Chan Gil Jeung hyun jea sung Yoo sik Yoon Kyoo Seok Ahn Medical Research & Development Team Korea Institute of Oriental Medicine Department of biomedical Engineering Kyunghee University Korea Electrotechnology Research Institute College of Oriental Medicine Semyung University Kyunghee University Oriental Medical College Pathology Laboratory

Objective:This study was to determine the standard of criteria for each different diagnosis of signs and symptoms. Methods: Eleven experts were asked to evaluate the adequateness of criteria that was developed by Korea Institute of Oriental Medicine (KIOM) and suggested the amendment of them. To perform the study, we used the questionnaire which asks about the diagnosis criteria for an insufficiency of the heart-qi (心气虚证), deficiency of the heart blood (心血虚证), deficiency of the heart-yin (心阴虚证), insuffi-

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Plasma Science and Technology 2009年第5期11卷 550-554页

作者： Seung-hyun KIM Youn-jea KIM School of Mechanical Engineering Sungkyunkwan University

In this study, numerical analysis is performed to adopt the equivalence ratio on the high velocity oxygen fuel （HVOF） thermal spray coating systems equipped with a minimum length nozzle. The analysis is applied to investigate the axisymmetric, steady-state, turbulent, and chemically combusting flow both within the torch and in a free jet region between the torch and the substrate to be coated. The combustion is modeled using a single-step and eddy-dissipation model which assumes that the reaction rate is limited by the turbulent mixing rate of the fuel and oxidant. As the diameter of the nozzle throat is increased, the location of the Mach shock disc moves backward from the nozzle exit. As the throat diameter and the divergent portion are 6 mm and 8 mm, respectively, the pressure in the HVOF system is the lowest at the chamber and the expanding gas is steadily maintained with both high velocity and high temperature for different equivalence ratios. Thus, relatively minor amendments of the equivalence ratio and the geometry of HVOF can lead to improved control over coating characteristics.

关键词： minimum length nozzle HVOF equivalence ratio

Numerical study on the heat dissipation characteristics of high-power LED module

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Science China(Technological Sciences) 2013年第9期56卷 2150-2155页

作者： LEE DaeWoo CHO sung-Wook KIM Youn-jea Graduate School of Mechanical Engineering Sungkyunkwan University School of Mechanical Engineering Sungkyunkwan University

LED lighting has problems such as short life span, power reduction due to the LED chip's heat, and decreased luminance efficiency etc. Many studies on the optimization of the thermal performance of LEDs have been conducted actively to solve these problems. The present study changes the fin shape and intervals of various heat sink designs so that LED can effectively produce a thermal effect. The water-cooling heat release system and the heat pipe methods show higher thermal performance results than the existing systems; however, the system is of high cost and requires a large-scale apparatus. This study carried out a numerical analysis of the thermal control system by applying heat flux and heat sink properties as an active heat release system using the commercial code ANSYS ver. 13.0 and verified the validity of the new heat sink design for temperature distribution analysis.

关键词： LED lighting water-cooling heat release system heat loss

Benchmark Computations of the Phase Field Crystal and Functionalized Cahn-Hilliard Equations via Fully Implicit,Nesterov Accelerated Schemes

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Communications in Computational Physics 2023年第2期33卷 367-398页

作者： jea-hyun Park Abner J.Salgado Steven M.Wise Department of Mathematics University of California Santa BarbaraCA 93106USA Department of Mathematics University of Tennessee KnoxvilleTN 37996USA.

We introduce a fast solver for the phase field crystal(PFC)and functionalized Cahn-Hilliard(FCH)equations with periodic boundary conditions on a rectangular domain that features the preconditioned Nesterov’s accelerated gradient descent(PAGD)*** discretize these problems with a Fourier collocation method in space,and employ various second-order schemes in *** observe a significant speedup with this solver when compared to the preconditioned gradient descent(PGD)*** the PAGD solver,fully implicit,second-order-in-time schemes are not only feasible to solve the PFC and FCH equations,but also do so more efficiently than some semi-implicit schemes in some cases where accuracy issues are taken into *** computations of four different schemes for the PFC and FCH equations are conducted and the results indicate that,for the FCH experiments,the fully implicit schemes(midpoint rule and BDF2 equipped with the PAGD as a nonlinear time marching solver)perform better than their IMEX versions in terms of computational cost needed to achieve a certain *** the PFC,the results are not as conclusive as in the FCH experiments,which,we believe,is due to the fact that the nonlinearity in the PFC is milder nature compared to the FCH *** also discuss some practical matters in applying the *** introduce an averaged Newton preconditioner and a sweeping-friction strategy as heuristic ways to choose good preconditioner *** sweeping-friction strategy exhibits almost as good a performance as the case of the best manually tuned parameters.

关键词： Phase field crystal functionalized Cahn-Hilliard preconditioning Nesterov acceleration nonlinear solver.

Improved continuous precipitation kinetics and tensile properties of extruded AZ80 alloy through {10-12} twin formation

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Journal of Magnesium and Alloys 2023年第9期11卷 3323-3337页

作者： hyun Ji Kim Sumi Jo sung Hyuk Park Department of Materials Science and Metallurgical Engineering Kyungpook National UniversityDaegu 41566the Republic of Korea

This study investigates the effect of{10-12}deformation twins on the continuous precipitation behavior of an extruded Mg-8.0Al-0.5Zn-0.2Mn(AZ80)alloy during *** extruded AZ80 alloy is compressed along the transverse direction to introduce{10-12}twins,followed by an aging treatment at 300℃.The extruded material exhibits a twin-free microstructure with low internal strain energy,whereas the pre-twinned material possesses abundant{10-12}twins and has high internal strain *** aging results reveal that the peak-aging time of the pre-twinned material(1 h)is one-eighth of that of the extruded material(8 h).Although Mg_(17)Al_(12)continuous precipitates(CPs)are observed in both the peak-aged materials,these CPs are much smaller and more densely distributed in the pre-twinned material despite the significantly shorter aging *** CPs size in the peak-aged materials increases in the following order:twinned region in the pre-twinned material(0.47μm)

关键词： AZ80 alloy {10-12}twin Aging Continuous precipitation Tensile properties

Three-dimensional spongy nanographene-functionalized silicon anodes for lithium ion batteries with superior cycling stability

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Nano Research 2018年第1期11卷 233-245页

作者： Chunfei Zhang Tong-hyun Kang Jong-sung Yu Department of Energy Systems Engineering DGIST Daegu 42988 Republic of Korea

An innovative spongy nanographene （SG） shell for a silicon substrate was prepared by low-temperature chemical vapor deposition on a hierarchical nickel nanotemplate. The SG-functionalized silicon （Si@SG） composite shows outstanding properties, which may be helpful to overcome issues affecting current silicon anodes used in lithium ion batteries such as poor conductivity, large volume expansion and high mass transfer resistance. The hierarchical nanographene shell exhibits elastic, sponge-like features that allow it to self-adaptively change its volume to accommodate the volume expansion of silicon. In addition, the porous, spongy framework containing randomly stacked graphene nanosheets presents low diffusion barriers and provides sufficiently free and short-haul channel segments to allow the fast migration of Li and electrolyte ions. The unique properties of the present silicon anode result in excellent electrochemical performances in terms of long-term cycling stability （95% capacity retention after 510 cycles）, rate performance, and cycling behavior for high mass loadings at different current densities.

关键词： spongy nanographene core-shell silicon lithium ion battery three-dimensionalstructure

Torsional vibration analysis of lathe spindle system with unbalanced workpiece

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Journal of Central South University 2011年第1期18卷 171-176页

作者：郭瑞 JANG sung-hyun CHOI Young-Hyu School of Mechatronics Changwon National University

For the purpose of analyzing the torsional vibration caused by the gravitational unbalance torque arisen in a spindle system when it is machining heavy work piece,a 10-DOF lumped parameter model was made for the machine tool spindle system with geared *** using the elementary method and Runge-Kutta method in Matlab,the eigenvalue problem was solved and the pure torsional vibration responses were obtained and *** results show that the spindle system cannot operate in the desired constant rotating speed as far as the gravitational unbalance torque is engaged,so it may cause bad effect on machining *** the torsional vibration increases infinitely near the resonant frequencies,so the spindle system cannot operate normally during these spindle speed ranges.

关键词： unbalanced work piece gravitational unbalance torque torsional vibration spindle system geared transmission

Counter-balancing effects of Si on C partitioning and stacking fault energy of austenite in 10Mn quenching and partitioning steel

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Journal of Materials Science & Technology 2022年第3期98卷 248-257页

作者： Dong Hwi Kim Jee-hyun Kang Hojun Gwon Joo hyun Ryu sung-Joon Kim Graduate Institute for Ferrous Technology Pohang University of Science and TechnologyPohang 37673Republic of Korea School of Materials Science and Engineering Institute of Materials TechnologyYeungnam UniversityGyeongsan 38541Republic of Korea POSCO Technical Research Laboratories POSCOGwangyang 57807Republic of Korea

Silicon is an essential alloying element in quenching and partitioning(Q&P)steels,because it is known to suppress carbide precipitation during partitioning step and promote carbon partitioning to stabilize *** 2 wt%Si was added to 10Mn-2Al-0.2C steel,the size and fraction of the carbides formed during partitioning became smaller than in the Si-free ***,the suppression of carbide formation promoted C partitioning into austenite as ***,austenite stability was always lower with Si under the equivalent partitioning condition because Si effectively decreased the stacking fault energy of *** partitioning progressed,the both yield and tensile strengths of the Si-added steel exceeded that of the Si-free steel with the similar ductility *** was because Si was an effective solid solution strengthener,and the austenite in the Si-added steel exhibited the appropriate stability to gradually transform into martensite throughout the *** resulting strengthening effect compensated for the softening caused by martensite ***,strain hardening rate decreased continuously throughout deformation,which resulted in high tensile strength and ductility.

关键词： Steels Q&P steel Silicon Austenite stability Tensile deformation Stacking fault energy Medium Mn steel

Acceleration of aging behavior and improvement of mechanical properties of extruded AZ80 alloy through(10–12) twinning

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Journal of Magnesium and Alloys 2023年第2期11卷 671-683页

作者： hyun Ji Kim Ye Jin Kim sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea

The effects of pre-existing {10–12} extension twins on the precipitation behavior of an extruded AZ80 material during aging and on its mechanical properties after peak aging are investigated. The material containing {10–12} twins-which are formed by compression before aging(twinned material)-has a finer grain size and higher dislocation density than the extruded material. Although the peak hardnesses of the twinned and extruded materials are almost the same, the time to reach the peak hardness is considerably shorter in the former material than in the latter(4 h and 24 h, respectively). In the twinned material, the high dislocation density of the {10–12} twins promotes continuous precipitation, which results in the formation of numerous fine Mg17Al12precipitates within the twins in the early stage of *** formation of these continuous precipitates reduces the driving force for discontinuous precipitation, which consequently suppresses the formation and growth of coarse Mg17Al12precipitates at the grain boundaries. Despite its shorter peak-aging time, the 4 h-peak-aged twinned material shows higher tensile strength and elongation than the 24 h-peak-aged extruded material. These higher mechanical properties of the former material are attributed primarily to the presence of more abundant fine continuous precipitates, which are effective in strengthening the material, and less abundant coarse discontinuous precipitates, which can act as crack initiation sites. These results demonstrate that the introduction of {10–12} twins into wrought Mg–Al-based alloys can accelerate the Mg17Al12precipitation kinetics considerably and improve the strength and ductility of the peak-aged alloys simultaneously.

关键词： AZ80 alloy Twin Aging Precipitation Tensile properties