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Mechanical properties of graphene oxide?silk fibroin bionanofilms via nanoindentation experiments and finite element analysis

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Friction 2022年第2期10卷 282-295页

作者： hyeonho CHO Joonho LEE Hyundo hwang Woonbong hwang Jin-Gyun KIM Sunghan KIM School of Mechanical Engineering Chung-Ang UniversitySeoul 06974Republic of Korea Department of Mechanical Engineering(Integrated Engineering) Kyung Hee UniversityGyeonggi 17104Republic of Korea Department of Mechanical Engineering POSTECHPohang 37673Republic of Korea Department of Robotics&Mechatronics.Korea Institute of Machinery&Materials Daejeon 34103Republic of Korea

Understanding the mechanical properties of bionanofilms is important in terms of identifying their *** primary focus of this study is to examine the effect of water vapor annealed silk fibroin on the indentation modulus and hardness of graphene oxide-silk fibroin(GO-SF)bionanofilms through nanoindentation experiments and finite element analysis(FEA).The GO-SF bionanofilms were fabricated using the layer-by-layer *** water vapor annealing process was employed to enhance the interfacial properties between the GO and SF layers,and the mechanical properties of the GO-SF bionanofilms were found to be affected by this *** employing water vapor annealing,the indentation modulus and hardness of the GO-SF bionanofilms can be ***,the FEA models of the GO-SF bionanofilms were developed to simulate the details of the mechanical behaviors of the GO-SF *** difference in the stress and strain distribution inside the GO-SF bionanofilms before and after annealing was *** addition,the load-displacement curves that were obtained by the developed FEA model conformed well with the results from the nanoindentation *** summary,this study presents the mechanism of improving the indentation modulus and hardness of the GO-SF bionanofilms through the water vapor annealing process,which is established with the FEA simulation models.

关键词： graphene oxide silk fibroin layer-by-layer(LbL) nanoindentation finite element analysis(FEA)

Enhancement of GAO's Multiparty Quantum Secret Sharing

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Communications in Theoretical Physics 2011年第7期56卷 79-82页

作者： Cheng-Chieh hwang Tzonelih hwang Chuan-Ming Li Department of Computer Science and Information Engineering National Cheng Kung University Department of Information Management Shu-Zen College of Medicine and Management

A multiparty quantum secret sharing (MQSS) protocol with two-photon three-dimensional Bell states was proposed by Gao [Commun. Theor. Phys. 52 (2009) 421] recently. This study points out that the performance of Gao's protocol can be much improved by using the technique of decoy single photons and carefully modifying the protocol to remove some unnecessary unitary operations, devices, and transmissions.

关键词： quantum secret sharing Greenberger-Horne-Zeilinger state

Effect of reduction in area per pass on strain distribution and microstructure during caliber rolling in twinning-induced plasticity steel

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Journal of Iron and Steel Research International 2020年第1期27卷 62-74页

作者： Joong-ki hwang Sung Jin Kim School of Mechanical Engineering Tongmyong UniversityBusan 48520Republic of Korea Department of Advanced Materials Engineering Sunchon National UniversitySuncheon 57922Republic of Korea

The effects of reduction in area(RA)per pass during caliber rolling on microstructure and strain distribution of twinninginduced plasticity steel have been investigated to find solutions to make a more homogeneous material along the radial direction for wire rod *** steel wires subjected to an average RA per pass of 2.5%(skin pass caliber rolling)and 10.0%(conventional caliber rolling)were *** skin pass caliber-rolled wire was characterized as a duplex fiber texture of majorand minor.and the textures were almost same at/between center and surface area,which is totally different from those of conventional caliber rolling and wire *** skin pass caliber rolling led to more homogeneous microstructure and mechanical properties along the radial direction in comparison with the conventional caliber rolling and wire drawing due to the more homogeneous Hall-Petch hardening,dislocation hardening,and texture behavior with area,resulting in higher formability.

关键词： Twinning-induced plasticity steel Caliber rolling Deformation twin Reduction in area Skin pass

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

L^(p)Boundedness of Fourier Integral Operators in the Class S_(1,0)

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Acta Mathematica Sinica,English Series 2023年第1期39卷 37-98页

作者： Ing-Lung hwang Department of Mathematics “National Chung Cheng University of Taiwan”Chiayi County 621003China

We prove the following properties:(1)Let a∈Λ_(1,0,k,k’)^(m0)(R^(n)×R^(n))with m0=-1|1/p-1/2|(n-1),n≥2(1 n/p,k’>0;2≤p≤∞,k>n/2,k’>0 respectively).Suppose the phase function S is positively homogeneous inξ-variables,non-degenerate and satisfies certain *** the Fourier integral operator T is L^(p)-*** the method of(1),we can obtain the L^(p)-boundedness of the Fourier integral operator if(2)the symbol a∈Λ_(1,δ,k,k’)^(m0),0≤δ≤1,with m0,k,k’and S given as in(1).Also,the method of(1)gives:(3)a∈Λ_(1,δ,k,k’),0≤δ<1 and k,k’given as in(1),then the L^(p)-boundedness of the pseudo-differential operators holds,1

关键词： Fourier integral operator L^(p)-boundedness

Review on Tidal Energy Technologies and Research Subjects

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China Ocean Engineering 2020年第1期34卷 137-150页

作者： Chul Hee JO Su Jin hwang Department of Naval Architecture and Ocean Engineering Inha University

Tidal current power is one of the promising and reliable renewable energies with the advantage of continuous and predictable resource. It can make stable electricity regardless of weather conditions or seasons all year around. The required technologies for tidal current power in the ocean have been developed for years and now recognized that it could be commercialized after intensive field tests and successful demonstrations. There are several tidal farm development projects in the world, such as the MeyGen project in UK with its commercialization at hand. However, various research subjects in the tidal current energy field are seeking improvements and industrialization of tidal current power in terms of economy and technical reliability. This paper introduces the resource assessment procedure of tidal energy that has been applied in Korea coastal regions. The key research subjects for tidal current power together with the interaction effect of multi-arrangement is described. Also, this paper is to introduce the research output of each subject such as turbine design, experimental validation, turbine interaction and wake, multi-array module, FSI (fluid-structure interaction), and duct application.

关键词： tidal current power resource assessment turbine design experimental validation turbine interaction multi arrangement FSI(fluid-structure interaction)

Characterization of flexible copper laminates fabricated by Cu electro-plating 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 965-969页

作者： Chang-Min LEE Jun-Hyung LIM Soo-Min hwang Eui-Cheol PARK Jong-Hyun SHIM Jin-Hyun PARK Jinho JOO Seung-Boo jung School of Advanced Materials Science and Engineering Sungkyunkwan University

Flexible copper clad laminates(FCCLs) were fabricated using the electro-plating process and the combined effect of the current density and plating time on their surface morphology,texture,hardness,electrical resistivity and folding behavior was *** achieve Cu layers with similar thicknesses,the current density was varied in the range of 0.2-3 A/dm2 and the plating time was controlled in the range of 0.5-7.5 h to compensate for the variation of the current *** surface morphology,hardness,and folding behavior were characterized by atomic force microscopy,nanoindentation technique and Massachusett Institute of Technology folding endurance test,*** X-ray diffraction patterns indicated that the Cu phase was formed without any secondary phases;however,the preferred orientation changed from(220) to(111) as the current density increased over 1 A/*** addition,it was observed that the root-mean-square and hardness values decreased when the current density increased and the plating time decreased *** electrical resistivity was as low as approximately 21 nΩ·m and the number of cycles without failure in the folding test was over 15 000,which were comparable to those of commercial FCCLs.

关键词：电镀工艺层压板铜层制备表征电流密度原子力显微镜纳米压痕技术

A Method for Detecting Non-Mask Wearers Based on Regression Analysis

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Computers, Materials & Continua 2022年第9期72卷 4411-4431页

作者： Dokyung hwang hyeonmin Ro Naejoung Kwak Jinsang hwang Dongju Kim POSTECH Institute of Artificial Intelligence Pohang24257Korea Department of Information Security at Pai Chai University Daejeon35345Korea Department of Safety and Emergency Management at Kyungwoon University Gumi39160Korea

A novel practical and universal method of mask-wearing detection has been proposed to prevent viral respiratory *** proposed method quickly and accurately detects mask and facial regions using welltrained You Only Look Once(YOLO)detector,then applies image coordinates of the detected bounding box(bbox).First,the data that is used to train our model is collected under various circumstances such as light disturbances,distances,time variations,and different climate *** also contains various mask types to detect in general and universal application of the *** detect mask-wearing status,it is important to detect facial and mask region accurately and we created our own dataset by taking picture of ***,the Convolutional Neural Network(CNN)model is trained with both our own dataset and open dataset to detect under heavy foot-traffic(Indoors).To make the model robust and reliable in various environment and situations,we collected various sample data in different *** through the experiment,we found out that there is a particular gradient according to the mask-wearing *** proposed method searches the point where the distance between the gradient for each state and the coordinate information of the detected object is the *** it carry out the classification of mask-wearing status of detected ***,we defined and classified three different mask-wearing states according to the mask’s position(With mask,Wear a mask around chin and Without mask).The gradient according to the mask-wearing status,is analyzed through linear *** regression interpretation is based on coordinate information of mask-wearing status and the sample data collected in simulated environment that considering distances between objects and the camera in the World Coordinate *** the experiments,we found out that linear regression analysis is more suitable than logistic regression analysis for classification of people wea

关键词： Automatic quarantine process detection of improper mask wearers facial image coordinates convolution neural network

Experimental Investigation of Aerodynamic Performance due to Blade Tip Clearance in a Gas Turbine Rotor Cascade

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Journal of Thermal Science 2022年第1期31卷 173-178页

作者： CHUNG Jinmoo BAEK Seungchan hwang Wontae Department of Mechanical Engineering Seoul National UniversitySeoul 08826Republic of Korea Institute of Advanced Machines and Design Seoul National UniversitySeoul 08826Republic of Korea Institute of Engineering Research Seoul National UniversitySeoul 08826Republic of Korea

This study examines how the complex flow structure within a gas turbine rotor affects aerodynamic loss. An unshrouded linear turbine cascade was built, and velocity and pressure fields were measured using a 5-hole probe. In order to elucidate the effect of tip clearance, the overall aerodynamic loss was evaluated by varying the tip clearance and examining the total pressure field for each case. The tip clearance was varied from 0% to 4.2% of blade span and the chord length based Reynolds number was fixed at 2×10^(5). For the case without tip clearance, a wake downstream of the blade trailing edge is observed, along with hub and tip passage vortices. These flow structures result in profile loss at the center of the blade span, and passage vortex related losses towards the hub and tip. As the tip clearance increases, a tip leakage vortex is formed, and it becomes stronger and eventually alters the tip passage vortex. Because of the interference of the secondary tip leakage flow with the main flow, the streamwise velocity decreases while the total pressure loss increases significantly by tenfold in the last 30% blade span region towards the tip for the 4.2% tip clearance case. It was additionally observed that the overall aerodynamic loss increases linearly with tip clearance.

关键词： gas turbine turbine cascade aerodynamic loss tip clearance tip leakage