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Fabrication of two-layer flexible copper clad laminate by electroless-Cu plating on surface modified polyimide

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中国有色金属学会会刊：英文版 2009年第4期19卷 970-974页

作者： Soo-Min HWANG Jun-Hyung LIM Chang-Min LEE eui-cheol park Jun-Hyuk CHOI Jinho JOO Hoo-Jeong LEE Seung-Boo JUNG School of Advanced Materials Science and Engineering Sungkyunkwan University

A flexible copper clad laminate(FCCL) was fabricated using electroless-and electro-Cu plating processes and the effects of pre-treatment time on the adhesion strength of the FCCL were evaluated based on interfacial *** neutralization and catalyst time were varied in the range of 0-20 min and 0.1-10 min,respectively,and the interfacial condition of the FCCL was characterized by atomic force microscopy(AFM) and X-ray photoelectron spectroscopy(XPS).It is observed that the peel strength increases significantly as the neutralization and catalyst time *** strength as high as 7.2-7.3 N/cm is obtained as the neutralization and catalyst time increase up to 20 min and 10 min,respectively,which is comparable to the strength achieved by the conventional laminating and sputtering *** improvements are probably due to an increase in the surface roughness of polyimide(PI),the activated surface condition,and the adsorption of palladium ions/atoms(Pd) on the PI surface which act as nucleation sites for Cu.

关键词：聚酰亚胺表面改性化学制备层压板铜电镀铜箔软性 X射线光电子能谱

Roles of humidity and heat treatment temperatures on YBa_2Cu_3O_(7-x) coated conductors by trifluoroacetic acid-metal organic deposition process

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中国有色金属学会会刊：英文版 2009年第4期19卷 956-960页

作者： Seok-Hern JANG Jun-Hyung LIM Chang-Min LEE eui-cheol park Soo-Min HWANG Jun-Hyuk CHOI Jong-Hyun SHIM Jin-Hyun park Won KIM Jinho JOO School of Advanced Materials Science and Engineering Sungkyunkwan University

YBa2Cu3O7-x(YBCO) films were fabricated on an LAO substrate using the trifluoroacetic acid-metal organic deposition(TFA-MOD) method and the effects of the humidity and heat treatment temperatures on the microstructure,degree of texture and critical properties of the films were *** order to understand the combined effects of the humidity and the calcining and firing temperatures on critical properties,heat-treatment was performed at various temperatures with the other processing variables *** films were calcined at 400-430 ℃ and fired at 750-800 ℃ in a 0-12.1% humidified Ar-O2 *** texture was determined by pole-figure *** amount of the BaF2 phase was effectively reduced and a sharp and strong biaxial texture was formed under a humidified atmosphere,which led to increased critical *** addition,the microstructure varied significantly with firing temperature but changed little with calcining *** highest IC of 40 A/cm-width,which corresponds to JC value of 1.8 MA/cm2,was obtained for the films fired at 775 ℃(in 12.1% humidity) after calcining at 400-430 ℃.It is likely that the highest IC value is due to the formation of a more pure YBCO phase,c-axis grains,and a denser microstructure.

关键词： YBa2Cu3O7 热处理温度三氟乙酸沉积过程湿度涂层导体有机金属微观结构变化

Parameter estimation for building energy models using GRcGAN

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Building Simulation 2023年第4期16卷 629-639页

作者： Hansol Shin cheol-Soo park Department of Architecture and Architectural Engineering College of EngineeringSeoul National UniversitySeoul08826R.O.Korea Institute of Construction and Environmental Engineering Institute of Engineering ResearchCollege of EngineeringSeoul National UniversitySeoul08826R.O.Korea

Parameter estimation methods can be classified into(1)manual(trial-and-error),(2)numerical optimization(optimization,sampling),(3)Bayesian inference(Bayes filter,Bayesian calibration),and(4)machine learning(generative model).Bayesian calibration has been widely used because it can capture stochastic nature of uncertain ***,the results of Bayesian calibration could be biased by(1)the prior distribution assumed by the expert’s subjective judgment;(2)the likelihood function that cannot always describe the true likelihood;and(3)the posterior distribution approximation method,such as the Markov Chain Monte Carlo,which requires significant computation *** overcome this,a new approach using a generator-regularized continuous conditional generative adversarial network(GRcGAN)is presented in this *** target parameters of the DOE reference building model were *** was trained to estimate uncertain parameters using simulated monthly electricity and gas *** can successfully estimate five uncertain parameters based on 1,000 training data *** proposed approach presents a potential for stochastic parameter estimation.

关键词： generative adversarial networks generative model parameter estimation inverse problem model calibration parameter uncertainty

The electronic structure and intervalley coupling of artificial and genuine graphene superlattices

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Nano Research 2016年第4期9卷 1101-1115页

作者： Pilkwang Kim cheol-Hwan park Department of Physics and Astronomy Seoul National University Seou108826 Republic of Korea

The so-called artificial graphene is an artificial material whose low-energy carriers are described by the massless Dirac equation. Applying a periodic potential with triangular symmetry to a two-dimensional electron gas is one approach to make such a material. According to recent experimental results, it is now possible to realize artificial graphene in the lab and to even apply an additional lateral, one-dimensional periodic potential to it. We name the latter system an artificial graphene superlattice in order to distinguish it from a genuine graphene superlaedce made from graphene. In this study, we investigate the electronic structure of artificial graphene superlattices, which exhibit the emergence of energy band gaps, merging and splitting of the Dirac points, etc. Then, from a similar investigation on genuine graphene superlattices, we show that many of these features originate from the coupling between Dirac fermions residing in two different valleys--the intervaUey coupling. Furthermore, contrary to previous studies, we find that the effects of intervalley coupling on the electronic structure cannot be ignored, irrespective of the length of the spatial period of the superlattice.

关键词： graphene artificial graphene graphene superlattice intervaUey coupling

Design and Demonstration of a Locust-Like Jumping Mechanism for Small-Scale Robots

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Journal of Bionic Engineering 2012年第3期9卷 271-281页

作者： Quoc-Viet Nguyen Hoon cheol park Department of Advanced Technology Fusion Konkuk University Seoul 143-701 Republic of Korea

A jumping mechanism can be an efficient mode of motion for small robots to overcome large obstacles on the ground and rough terrain. In this paper, we present a 7 g prototype of locust-inspired jumping mechanism that uses springs, wire, reduction gears, and a motor as the actuation components. The leg structure and muscles of a locust or grasshopper were mimicked using springs and wire, springs for passive extensor muscles, and a wire as a flexor muscle. A small motor was used to slowly charge the spring through a lever and gear system, and a cam with a special profile was used as a clicking mechanism for quick release of elastic energy stored in the springs to create a sudden kick for a quick jump. Performance analysis and experiments were conducted for comparison and performance estimation of the jumping mechanism prototype. Our prototype could produce standing jumps over obstacles that were about 14 times its own size （approximate to 71 cm） and a jumping distance of 20 times its own size （approximate to 100 cm）.

关键词： biomimetics locust jumping mechanism passive tibia extensor muscle

Generation of Control Moments in an Insect-like Tailless Flapping-wing Micro Air Vehicle by Changing the Stroke-plane Angle

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Journal of Bionic Engineering 2016年第3期13卷 449-457页

作者： Hoang Vu Phan Hoon cheol park Artificial Muscle Research Center Konkuk University Seoul 143-701 South Korea Deptment of Advanced Technology Fusion Konkuk University Seoul 143-701 South Korea

We propose a control moment generator to control the attitude of an insect-like tailless Flapping-wing Micro Air Vehicle （FW-MAV）, where the flapping wings simultaneously produce the flight force and control moments. The generator tilts the stroke plane of each wing independently to direct the resultant aerodynamic force in the desired direction to ultimately generate pitch and yaw moments. A roll moment is produced by an additional mechanism that shifts the trailing edge, which changes the wing rotation angles of the two flapping wings and produces an asymmetric thrust. Images of the flapping wings are captured with a high-speed camera and clearly show that the FW-MAV can independently change the stroke planes of its two wings. The measured force and moment data prove that the control moment generator produces reasonable pitch and yaw moments by tilting the stroke plane and realizes a roll moment by shifting the position of the trailing edge at the wing root.

关键词： insect-like Flapping-wing Micro Air Vehicle (FW-MAV) control mechanism stroke plane beetle flight

Influence of Center of Gravity Location on Flight Dynamic Stability in a Hovering Tailless FW-MAV: Lateral Motion

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Journal of Bionic Engineering 2020年第1期17卷 148-160页

作者： Loan Thi Kim Au Hoon cheol park Department of Smart Vehicle Engineering and Artificial Muscle Research Center Konkuk UniversitySeoul 05029Korea

This paper reports the effect of the Center of Gravity(CG)position on lateral flight dynamic stability of hovering KUBeetle,a tailless FW-MAV,providing further insights on the effects of asymmetries in body mass distribution and wing *** the current study,the standard linearized equations of motion were applied as in the previous work on longitudinal dynamic *** stability derivatives were acquired using the computational fluid dynamic methods via the commercial software of ANSYS *** exists a stable region for CG between 2.6%and 3.5%of the mean chord below the wing pivot point,in which the lateral motion of hovering KUBeetle is passively *** CG below the stable region,because of an unstable oscillatory mode,the lateral motion of the FW-MAV is unstable but can be stabilized using rolling rate *** CG above the stable region,because of a divergence mode,the system remains unstable even with the rolling rate *** with other works on an FW-MAV based on a quasi-steady aerodynamic model and on insect showed similar characteristics for flapping *** is also interesting to note that the asymmetries in body mass and wing kinematics can enlarge the stable region of the system by a non-zero Ixz which approaches the root square of√IxIz,a negative LrNp,and a positive Ix2(Ir+Np).Combining the current result with that of the previous work on longitudinal motion,the most beneficial region of the CG for full 6-DOF flight dynamic stability of hovering KUBeetle was suggested.

关键词： FW-MAV center of gravity flight dynamic stability lateral motion asymmetry computational fluid dynamics bioinspired flight

Influence of Center of Gravity Location on Flight Dynamic Stability in a Hovering Tailless FW-MAV:Longitudinal Motion

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Journal of Bionic Engineering 2019年第1期16卷 130-144页

作者： Loan Thi Kim Au Hoon cheol park Department of Smart Vehicle Engineering and Artificial Muscle Research Center Konkuk UniversitySeou105029Korea

The influence of Center of Gravity(CG)location on longitudinal dynamic stability of hovering KUBeetle,a tailless Flapping-Wing Micro Air Vehicle(FW-MAV),is reported in this *** rigid-body approximation was assumed,allowing application of the standard equations of motion used for fixed-wing *** each considered location of CG,stability derivatives were obtained using the computational fluid dynamics method via the commercial software of ANSYS *** dynamic stability was studied using technique of eigenvalue *** exists a narrow stable region for CG between 23%-24%of mean chord above the wing pivot point,where the longitudinal hovering of KUBeetle is passively *** CG is located below the stable region,the analysis identifies two subsidence modes and one unstable oscillatory mode,which makes the hovering of KUBeetle ***,it can be stabilized using pitching rate *** CG is located above the stable region,the system yields one stable oscillatory mode,one subsidence mode,and one divergence *** of the divergence mode,the system remains unstable even with the angular rate *** results share similar characteristics to another FW-MAV and *** study may provide a reference for FW-MAV developers.

关键词： center of gravity hovering longitudinal dynamic stability computational fluid dynamics flapping wings bioinspired flight

Expression of E-cadherin and α-catenin in a varicocele-induced infertility rat model

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Asian Journal of Andrology 2011年第3期13卷 470-475,514页

作者： Hong Koo Ha Hyun Jun park Nam cheol park Department of Urology Pusan National University School of Medicine Busan 602739 Korea Medical Research Institute Pusan National University Hospital Busan 602739 Korea

The roles of E-cadherin and α-catenin were evaluated in the development of varicocele-induced infertility. Analysis of the association between the expression of E-cadherinla-catenin and clinical/pathological parameters was performed. Thirty lO-week-old male rats （experimental group） were used for the experiments; the left renal vein was ligated to form a varicocele. The abdomen was incised in 30 rats （control group） and no procedure was performed on 10 rats （baseline group）. The weights of the left testis, serum reactive oxygen species （ROS）, testosterone, luteinizing hormone （LH）, follicle-stimulating hormone （FSH） and degenerative changes in the seminiferous tubules after 4 and 8 weeks were recorded. The expression of E-cadherin and α-catenin was evaluated by immunohistochemical （IHC） staining and Western blot analysis. The ROS increased in the 8-week experimental group, compared with the baseline and control groups （P〈0.001 for both）. Additionally, FSH significantly increased in the 4- and 8-week experimental group compared with the control groups （P= 0.013 and P= 0.032, respectively）. The ratio of degenerative changes in the seminiferous tubules of the experimental groups increased. The IHC staining showed that the expression of E-cadherin and a-catenin decreased in the 4- and 8-week experimental groups. Similar to the IHC staining, the experimental group had decreased reactivity on Western blot analysis. The expression of E-cadherin and a-catenin was significantly associated with the ROS and degenerative changes in the seminiferous tubules. The results of this study suggest that damage to the blood-testis barrier （BTB） is associated with varicocele-induced male infertility, and that ROS may cause damage to the BTB.

关键词： α-catenin blood-testis barrier E-cadherin varicocele infertility