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Effective shape-controlled growth of monolayer MoS2 flakes by powder-based chemical vapor deposition

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Nano Research 2017年第1期10卷 255-262页

作者： Sang Yoon Yang Gi Woong shim seung-Bum Seo Sung-Yool Choi Graphene Research Center (GRC) Center for Advanced Materials Discovery for 3D Displays (CAMD3) School of Electrical EngineeringKorea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea

In the recent years, transition-metal dichalcogenides such as MoS2 have attracted considerable attention owing to their unique structure and electronic properties. Chemical vapor deposition （CVD） is a popular method for producing MoS2 flakes with different shapes. Here, we report an effective method for achieving a broad range of shape evolution in CVD-grown monolayer MoS2 flakes. By controlling the S and MoO3 temperatures, the shape of the monolayer MoS2 flakes was varied from hexagonal to triangular via intermediate shapes such as truncated and multi-apex triangles. The shape evolution of the MoS2 flakes can be explained by introducing the term “nominal Mo：S ratio”, which refers to the amount of loaded MoO3 and evaporated S powders. By using the nominal Mo：S ratio, we predicted the potential reaction atmosphere and effectively controlled the actual proportion of MoO3-x with respect to S in the growth region, along with the growth temperature. From the systematic investigation of the behavior of the shape evolution, we developed a shape-evolution diagram, which can be used as a practical guide for producing CVD-grown MoS2 flakes with desired shapes

关键词： molybdenum disulfide CVD growth shape evolution diagram growth condition

Early treadmill exercise increases macrophage migration inhibitory factor expression after cerebral ischemia/reperfusion

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Neural Regeneration Research 2019年第7期14卷 1230-1236页

作者： Min Cheol Chang Chae Ri Park seung Hwa Rhie Woo Hyun shim Dae Yul Kim Department of Rehabilitation Medicine College of MedicineYeungnam University Asan Institute for Life Sciences Asan Medical CenterUniversity of Ulsan College of Medicine Department of Rehabilitation Medicine Asan Medical CenterUniversity of Ulsan College of Medicine Department of Radiology Asan Medical CenterUniversity of Ulsan College of Medicine

The neuroprotective function of macrophage migration inhibitory factor(MIF) in ischemic stroke was rarely *** study aimed to investigate the effects of early treadmill exercise on recovery from ischemic stroke and to determine whether these effects are associated with the expression levels of MIF and brain-derived neurotrophic factor(BDNF) in the ischemic area.A total of 40 male Sprague-Dawley rats were randomly assigned to the ischemia and exercise group [middle cerebral artery occlusion(MCAO)-Ex,n = 10),ischemia and sedentary group(MCAO-St,n = 10),sham-surgery and exercise group(Sham-Ex,n= 10),or sham-surgery and sedentary group(Sham-St,n = 10).The MCAO-Ex and MCAO-St groups were subjected to MCAO for 60 minutes,whereas the Sham-Ex and Sham-St groups were subjected to an identical operation without *** in the MCAO-Ex and Sham-Ex groups then ran on a treadmill for 30 minutes once a day for 5 consecutive *** reperfusion,the hanging time tested by the wire hang test was longer and the relative fractional anisotropy determined by MRI was higher in the peri-infarct region of the MCAO-Ex group compared with the MCAO-St *** expression levels of MIF and BDNF in the peri-infarct region were upregulated in the MCAO-Ex *** MIF and BDNF levels were positively correlated with relative fractional anisotropy changes in the peri-infarct *** was no significant difference in the levels of MIF and BDNF in the peri-infarct region between the Sham-Ex and Sham-St *** study demonstrated that early exercise(initiated 48 hours after the MCAO) could improve motor and neuronal recovery after ischemic ***,the increased levels of MIF and BDNF in the peri-infarct region(penumbra) may be one of the mechanisms of enhanced neurological function *** experiments were approved by the Institutional Animal Care and Use Committee in Asan Medical Center in South Korea(2016-12-126).

关键词： ischemic stroke early exercise macrophage migration inhibitory factor brain-derived neurotrophic factor motor recovery neural regeneration

Surgical strategy of the treatment of atypical femoral fractures

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World Journal of Orthopedics 2023年第5期14卷 302-311页

作者： Bum-Jin shim Heejae Won Shin-Yoon Kim seung-Hoon Baek Department of Orthopedic Surgery Kyungpook National University Chilgok HospitalDaegu 41404South Korea Department of Orthopedic Surgery Kyungpook National UniversityCollege of MedincineDaegu 41944South Korea Department of Orthopedic Surgery Kyungpook National University HospitalKyungpook National UniversityCollege of MedincineDaegu 41944South Korea

The atypical femoral fracture(AFF)has been attracting significant attention because of its increasing incidence;additionally,its treatment is challenging from biological and mechanical *** surgery is often required to manage complete AFFs,clear guidelines for the surgical treatment of AFFs are currently *** reviewed and described the surgical treatment of AFFs and the surveillance of the contralateral *** complete AFFs,cephalomedullary intramedullary nailing spanning the entire length of the femur can be *** surgical techniques to overcome the femoral bowing common in AFFs include a lateral entry point,external rotation of the nail,and the use of a nail with a small radius of curvature,or a contralateral *** the case of a narrow medullary canal,severe femoral bowing,or pre-existing implants,plate fixation may be considered as an *** incomplete AFFs,prophylactic fixation depends on several risk factors,such as a subtrochanteric location,presence of a radiolucent line,functional pain,and condition of the contralateral femur;the same surgical principles as those in complete AFFs can be ***,once AFF is diagnosed,clinicians should recognize the increased risk of contralateral AFFs,and close surveillance of the contralateral femur is recommended.

关键词： Atypical femoral fracture Surgical treatment Surveillance Contralateral femur Femoral bowing

Guaranteeing almost fault-free tracking performance from transient to steady-state:a disturbance observer approach

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Science China(Information Sciences) 2018年第7期61卷 227-243页

作者： Gyunghoon PARK Hyungbo shim ASRI Department of Electrical and Computer Engineering Seoul National University

In this paper, we propose an output-feedback fault-tolerant controller(FTC) for a class of uncertain multi-input single-output systems under float and lock-in-place actuator faults. Of particular interest is to recover a fault-free tracking performance of a(pre-defined) nominal closed-loop system, during the entire time period including the transients due to abrupt actuator faults. As a key component, a highgain disturbance observer(DOB) is employed to rapidly compensate the lumped disturbance, a compressed expression of all the effect of actuator faults(as well as model uncertainty and disturbance) on the *** implement this high-gain approach, a fixed control allocation(CA) law is presented in order to keep an extended system with a virtual scalar input to remain of minimum phase under any patterns of faults. It is shown via the singular perturbation theory that the proposed FTC, consisting of the high-gain DOB and the CA law, resolves the problem in an approximate but arbitrarily accurate sense. Simulations with the linearized lateral model of Boeing 747 are performed to verify the validity of the proposed FTC scheme.

关键词： disturbance observer fault-tolerant control robust control performance recovery actuator fault

Estimation of vegetative mercury emissions in China

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Journal of Environmental Sciences 2008年第9期20卷 1070-1074页

作者： Shang Gyoo shim Korea Institute of Science and Technology

Vegetative mercury emissions were estimated within the framework of Biogenic Emission Inventory System (BEIS3 V3.11). In this estimation, the 19 categories of U.S. Geological Survey landcover data were incorporated to generate the vegetation-specific mercury emissions in a 81-km Lambert Conformal model grid covering the total Chinese continent. The surface temperature and cloud-corrected solar radiation from a Mesoscale Meteorological model (MM5) were retrieved and used for calculating the diurnal variation...

关键词： mercury emission Biogenic Emission Inventory System (BEIS3) natural source

Overlooked impact of precursor mixing:Implications in the electrochemical performance of battery electrode materials

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Journal of Energy Chemistry 2023年第7期82卷 56-65,I0003页

作者： JinHa shim Jin Ho Bang Department of Applied Chemistry Center for Bionano Intelligence Education and ResearchHanyang University55 Hanyangdaehak-roSangnok-guAnsanGyeonggi-do 15588Republic of Korea Department of Chemical and Molecular Engineering Hanyang University55 Hanyangdaehak-roSangnok-guAnsanGyeonggi-do 15588Republic of Korea

Solid-state reactions are an essential part of the synthesis of various cathode materials for lithium-ion batteries(LIBs).Despite the simplicity and effectiveness for mass production,a subtle variation in synthesis conditions can often give rise to unexpectedly different physical properties,significantly affecting the electrochemical performance of electrode ***,this aspect has long been overlooked in the LIB community,which should focus on advancement in understanding the influence of synthesis *** solid-state reactions occur only at the interface of precursor materials,maximizing the interfacial contact area between mixed precursor powders is *** milling and/or mixing are common practices that have been performed in both academia and industry for this *** the common belief that this pre-treatment before calcination would be of great benefit for the preparation of high-performance LIB materials,we revealed in this work that this practice is not always successful for this *** our case study of the preparation of LiCoO_(2),we demonstrated that mechanical mixing-a routinely implemented process for homogeneous mixing of precursors-can be harmful if it is performed without assuring optimal working conditions for *** underlying reasons for this surprising result are elucidated in this work,and we hope that this new insight can help avoid the potential pitfall of routine implementations performed for LIB materials.

关键词： LiCoO_(2) Solid-state reaction Mechanical mixing Cathode material Lithium-ion battery

Acceleration Workspace of Cooperating Multi-Finger Robot Systems

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Journal of Bionic Engineering 2008年第2期5卷 103-110页

作者： Hyungwon shim Jihong Lee BK21 Mechatronics Group Chungnam National University

We present a mathematical method for acceleration workspace analysis of cooperating multi-finger robot systems using a model of point-contact with friction. A new unified formulation from dynamic equations of cooperating multi-finger robots is derived considering the force and acceleration relationships between the fingers and the object to be handled. From the dynamic equation, maximum translational and rotational acceleration bounds of an object are calculated under given constraints of contact conditions, configurations of fingers, and bounds on the torques of joint actuators for each finger. Here, the rotational acceleration bounds can be applied as an important manipulability index when the multi-finger robot grasps an object. To verify the proposed method, we used a set of case studies with a simple multi-finger mechanism system. The achievable acceleration boundary in task space can be obtained successfully with the proposed method and the acceleration boundary depends on the configurations of fingers.

关键词： acceleration workspace multi-finger robots point-contact with friction model unified dynamic equation acceleration boundary

Multi-channel electromyography pattern classification using deep belief networks for enhanced user experience

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Journal of Central South University 2015年第5期22卷 1801-1808页

作者： shim Hyeon-min LEE Sangmin Institute for Information and Electronic Research Inha University 100 Inharo Incheon 402-751 Korea Department of Electronic Engineering Inha University 100 Inharo Incheon 402-751 Korea

An enhanced algorithm is proposed to recognize multi-channel electromyography(EMG) patterns using deep belief networks(DBNs). It is difficult to classify the EMG features because an EMG signal has nonlinear and time-varying ***, in several previous studies, various machine-learning methods have been applied. A DBN is a fast, greedy learning algorithm that can find a fairly good set of weights rapidly, even in deep networks with a large number of parameters and many hidden layers. To evaluate this model, we acquired EMG signals, extracted their features, and then compared the model with the DBN and other conventional classifiers. The accuracy of the DBN is higher than that of the other algorithms. The classification performance of the DBN model designed is approximately 88.60%. It is 7.55%(p=9.82×10-12) higher than linear discriminant analysis(LDA) and 2.89%(p=1.94×10-5) higher than support vector machine(SVM). Further, the DBN is better than shallow learning algorithms or back propagation(BP), and this model is effective for an EMG-based user-interfaced system.

关键词： electromyography(EMG) pattern classification feature extraction deep learning deep belief network(DBN)

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