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Additive manufacturing of flexible 3D surface electrodes for electrostatic adhesion control and smart robotic gripping

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Friction 2023年第11期11卷 1974-1986页

作者： dong Geun kim Hyeongmin JE AJohn HART Sanha kim Department of Mechanical Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea Department of Mechanical Engineering Massachusetts Institute of TechnologyCambridgeMA 02139USA

Mechanically flexible surface structures with embedded conductive electrodes are attractive in contact-based devices,such as those used in reversible dry/adhesion and tactile *** shapes of the surface structures strongly determine the contact behavior and therefore the resulting adhesion and sensing functionalities;however,available features are often restricted by fabrication ***,we additively manufacture elastomeric structure arrays with diverse angles,shapes,and sizes;this is followed by integration of conductive nanowire *** fabricated flexible three-dimensional(3D)surface electrodes are mechanically compliant and electrically conductive,providing multifunctional ability to sense touch and to switch adhesion via a combined effect of shear-and electro *** designed soft,anisotropic flexible structures to mimic the gecko’s reversible adhesion,which is governed by van der Waals forces;we integrated nanowires to further manipulate the localized electric field among the adjacent flexible 3D surface electrodes to provide additional means to digitally tune the electrostatic attraction at the contact *** addition,the composite surface can sense the contact force via capacitive *** our flexible 3D surface electrodes,we demonstrate a complete soft gripper that can grasp diverse convex objects,including metal,ceramic,and plastic products,as well as fresh fruits,and that exhibits 72%greater electroadhesive gripping force when voltage is applied.

关键词： electroadhesion tactile sensing robotic gripper additive manufacturing dry adhesive

Dynamic soil-structure interaction analysis in time domain based on a modified version of perfectly matched discrete layers

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第1期12卷 168-179页

作者： dong Van Nguyen Dookie kim Department of Civil Engineering Kunsan National University558 Daehak-roGunsan-si54150Republic of Korea

Analysis of soil-structure interaction is commonly conducted by dividing the infinite domain of the soil into two domains:interior and exterior *** interior domain is bounded in a small region,while the exterior domain is replaced by artificial boundary *** choice of artificial boundary conditions is a critical issue in the analysis of soil-structure interaction *** matched discrete layer(PMDL)has been proved as a good approach for modeling the exterior *** this study,a modified version of the PMDLs,*** with analytical wavelengths(AW-PMDLs),is used in the soil-structure interaction analysis in time domain,which essentially can be regarded as an extension of the analysis in frequency domain,being previously proven to be *** verifications are *** results demonstrate that the proposed method performs well in the analysis of soilstructure interaction problems in time domain.

关键词： Soil-structure interaction Time domain Wave propagation Wavelength Infinite domain Perfectly matched discrete layer(PMDL)

Combination of cell signaling molecules can facilitate MYOD1-mediated myogenic transdifferentiation of pig fibroblasts

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Journal of Animal Science and Biotechnology 2021年第4期12卷 1662-1674页

作者： Jinsol Jeong Kwang-Hwan Choi Seung-hun kim dong-Kyung Lee Jong-Nam Oh Mingyun Lee Gyung Cheol Choe Chang-Kyu Lee Department of Agricultural Biotechnology Animal Biotechnology Majorand Research Institute of Agriculture and Life ScienceSeoul National UniversitySeoul 08826South Korea Present address:Research and Development Center Space F corporationHwasung-siGyeonggi-do 18471South Korea Institute of Green Bio Science and Technology Seoul National UniversityPyeong ChangKangwon-do 25354South Korea

Background:Myogenic transdifferentiation can be accomplished through ectopic MYOD1 expression,which is facilitated by various signaling pathways associated with *** this study,we attempted to transdifferentiate pig embryonic fibroblasts(PEFs)myogenically into skeletal muscle through overexpression of the pig MYOD1 gene and modulation of the FGF,TGF-β,WNT,and cAMP signaling ***:The MYOD1 overexpression vector was constructed based on comparative sequence analysis,demonstrating that pig MYOD1 has evolutionarily conserved domains across various *** forced MYOD1 expression through these vectors triggered the expression of endogenous muscle markers,transdifferentiated muscle cells from fibroblasts were not ***,various signaling molecules,including FGF2,SB431542,CHIR99021,and forskolin,along with MYOD1 overexpression were applied to enhance the myogenic *** modified conditions led to the derivation of myotubes and activation of muscle markers in PEFs,as determined by qPCR and ***,a sarcomere-like structure was observed,indicating that terminally differentiated skeletal muscle could be obtained from transdifferentiated ***:In summary,we established a protocol for reprogramming MYOD1-overexpressing PEFs into the mature skeletal muscle using signaling *** myogenic reprogramming can be used as a cell source for muscle disease models in regenerative medicine and the production of cultured meat in cellular agriculture.

关键词： MYOD1 Pig Sequence analysis Skeletal muscle Transdifferentiation

Effects of Cr interlayer on mechanical and tribological properties of Cr-Al-Si-N nanocomposite coating

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Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 62-67页

作者： Young Su HONG Se hun KWON Tiegang WANG Doo-In kim Jihwan CHOI Kwang Ho kim School of Materials Science and Engineering Pusan National University National Core Research Center for Hybrid Materials Solution Pusan National University

Cr-A1-Si-N coatings were deposited on SUS 304 substrate by a hybrid coating system. A Cr interlayer was introduced between Cr-A1-Si-N coating and SUS 304 substrate to improve the coating adherence. The effects of Cr interlayer on the microhardness, adhesion, and tribological behavior of Cr-A1-Si-N coatings were systematically investigated. The results indicate that the microhardness of the Cr-A1-Si-N coatings gradually deceases with increasing thickness of Cr interlayers. The adhesion between Cr-A1-Si-N and SUS 304 substrate is improved by addition of the Cr interlayers. A peak critical load of-50 N is observed for the coating containing Cr interlayer of 60 nm as compared - 20 N for the coating without Cr interlayer. The thicker Cr interlayers result in reduced critical load values. Moreover, the wear resistance of the Cr-AI-Si-N coatings is greatly enhanced by introducing the Cr interlayer with thickness of 60 nm in spite of the decreased microhardness. The friction coefficient of the coating system is also moderately reduced.

关键词： Cr-A1-Si-N coating Cr interlayer hardness adhesion wear

Shear deformable finite beam elements for composite box beams

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Acta Mechanica Sinica 2014年第2期30卷 223-240页

作者： Nam-Il kim dong-Ho Choi Department of Architectural Engineering Sejong University Department of Civil and Environmental Engineering Hanyang University

The shear deformable thin-walled composite beams with closed cross-sections have been developed for coupled flexural, torsional, and buckling analyses. A theoretical model applicable to the thin-walled laminated composite box beams is presented by taking into account all the structural couplings coming from the material anisotropy and the shear deformation effects. The current composite beam includes the transverse shear and the restrained warping induced shear deformation by using the first-order shear deformation beam theory. Seven governing equations are derived for the coupled axial-flexural-torsional-shearing buckling based on the principle of minimum total potential energy. Based on the present analytical model, three different types of finite composite beam elements, namely, linear, quadratic and cubic elements are developed to analyze the flexural, torsional, and buckling problems. In order to demonstrate the accuracy and superiority of the beam theory and the finite beam elements developed by this study,numerical solutions are presented and compared with the results obtained by other researchers and the detailed threedimensional analysis results using the shell elements of ABAQUS. Especially, the influences of the modulus ratio and the simplified assumptions in stress-strain relations on the deflection, twisting angle, and critical buckling loads of composite box beams are investigated.

关键词： Thin-walled Composite box beam Deflection Twisting angle Buckling load Shear deformation

CHEBYSHEV WEIGHTED NORM LEAST-SQUARES SPECTRAL METHODS FOR THE ELLIPTIC PROBLEM

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Journal of Computational Mathematics 2006年第4期24卷 451-462页

作者： Sang dong kim Byeong Chun Shin Department of Mathematics Kyungpook National University Taegu 702-701 Korea Department of Mathematics Chonnam National University Kwangju 500-757 Korea

We develop and analyze a first-order system least-squares spectral method for the second-order elhptic boundary value problem with variable coefficients. We first analyze the Chebyshev weighted norm least-squares functional defined by the sum of the Lw^2- and Hw^-1- norm of the residual equations and then we eplace the negative norm by the discrete negative norm and analyze the discrete Chebyshev weighted least-squares method. The spectral convergence is derived for the proposed method. We also present various numerical experiments. The Legendre weighted least-squares method can be easily developed by following this paper.

关键词： Least-squares methods Spectral method Negative norm.

Effect of focal laser photocoagulation in eyes with mild to moderate non-proliferative diabetic retinopathy

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International Journal of Ophthalmology(English edition) 2016年第10期9卷 1439-1443页

作者： Seong hun Jeong Jung Il Han Sung Won Cho dong Won Lee Chul Gu kim Tae Gon Lee Jong Woo kim Department of Ophthalmology Kim's Eye HospitalMyung-Gok Eye Research InstituteKonyang University College of Medicine

AIM：To report the effect of focal laser photocoagulation on both the severity of hard exudates（HEs） and the rate of disease progression in eyes with mild to moderate non-proliferative diabetic retinopathy（NPDR）.METHODS： We retrospectively reviewed the medical records of 33 patients（60 eyes） who had been diagnosed with mild to moderate NPDR between January 2006 and December *** patients were divided into 2 groups：Group A（38 eyes in 20 patients treated using focal laser photocoagulation） and Group B（treated without laser photocoagulation）.We also reviewed the best corrected visual acuity measurements,and the fundus photographs taken at both baseline and follow-up visits. RESULTS： In Group A,HE severity grade had decreased significantly from baseline to the final visit（P 〈0.05）,but this was not the case in Group B（P =0.662）.The cumulative probabilities of retinopathy progression at 5y were 26% in Group A and 30% in Group *** survival curves showed no significant difference between the groups with regard to retinopathy progression（P =0.805）.CONCLUSION： Focal laser photocoagulation reduced the levels of HEs in eyes with mild to moderate ***,the treatment was not able to decelerate the progression of DR.

关键词： focal laser diabetic retinopathy retina non-proliferative diabetic retinopathy

Weldability evaluation and tensile strength estimation model for aluminum alloy lap joint welding using hybrid system with laser and scanner head

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中国有色金属学会会刊：英文版 2012年第S3期22卷 596-604页

作者： dong-Yoon kim Young-Whan PARK Department of Mechanical Engineering Pukyong National University

Aluminum welding using a hybrid system with a laser and scanner welding head was performed under various welding conditions to verify the feasibility of applying an aluminum alloy to a car *** experimental material was 5J32 aluminum alloy,and the laser power,welding speed,and laser incidence angle were used as the control *** weld bead shape and the tensile shear strength were evaluated in order to understand the aluminum lap joint weld *** of variance (ANOVA) was conducted to identify the effect of the process variables on the tensile shear *** strength estimation models using three different regression models were also *** input variables were the laser power,welding speed,and laser incidence angle,and the output was the tensile shear *** the models,the second-order polynomial estimation model had the best estimation performance,and the average error rate of this model was 0.058.

关键词： laser welding scanner remote welding 5J32 aluminum alloy regression model

EXPLICIT BOUNDS OF EIGENVALUES FOR STIFFNESS MATRICES BY QUADRATIC HIERARCHICAL BASIS METHOD)

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Journal of Computational Mathematics 2003年第2期21卷 113-124页

作者： Sang dong kim Byeong Chun SHIN Department of Mathematics Kyungpook National UniversityTaegu 702-701KoreaDepartment of MathematicsChonnam National UniversityGwangju 500-757Korea

The bounds for the eigenvalues of the stiffness matrices in the finite element discretization corresponding to Lu := - u' with zero boundary conditions by quadratic hierarchical basis are shown explicitly. The condition number of the resulting system behaves like O(1/h) where h is the mesh size. We also analyze a main diagonal preconditioner of the stiffness matrix which reduces the condition number of the preconditioned system to O(1).

关键词： hierarchical basis multilevel