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Supersonic Cavity Based Combustion with Kerosene/Hydrogen Fuel

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Journal of Thermal Science 2015年第2期24卷 164-172页

作者： Rajarshi Das Jeong Soo kim Heuy dong kim Department of Mechanical Engineering Andong National University School of Mechanical Engineering Pukyong National University

A comparative study with kerosene and hydrogen fuel in a model scramjet combustor has been carried out nu- merically. The effect of fuel-air equivalence ratio on the flow field properties in a cavity based mixing mechanism at a freestream Math number of 2.08 has been probed. The investigation has been carried out in a two dimension- al numerical model where a cavity of length to depth ratio of 2 is mounted on one of the walls of the flow channel The flow field shock structure is observed to change with the change in fuel-air equivalence ratio. Total pressure loss is observed to depend both on fuel air equivalence ratio and the fuel type. The spread of fuel in the test sec- tion shows marked variation with the equivalence ratio. Performance of injector location on the fuel-air mixing is also probed during the course of the investigation.

关键词： Scramjet fuel-air mixing kerosene hydrogen equivalence ratio

Nitric oxide synthase 2 gene polymorphisms are associated with prostatic volume in Korean men with benign prostatic hyperplasia

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Asian Journal of Andrology 2010年第5期12卷 690-696页

作者： Koo Han Yoo Su Kang kim Joo-Ho Chung Sung-goo Chang Department of Urology School of Medicine Kyung Hee University Seou1130-702 Korea Kohwang Medical Research Institute School of Medicine Kyung Hee University Seoul 130-702 Korea

The precise aetiology of benign prostatic hyperplasia （BPH） remains unclear; however, it is known that immunological inflammatory processes have a role in the pathogenesis of BPH initiation and progression. Nitric oxide synthase 2 （NOS2） inducible expression is closely correlated with prostatic disease, including prostate cancer and BPH. The aim of this study was to investigate the relationship between NOS2 polymorphisms and BPH. With a cohort of 205 controls and 229 BPH subjects, we genotyped three single nucleotide polymorphisms （SNPs） in the NOS2 gene, including rs2779248 （promoter, -278 T/C）, rs 10459953 （5＇-untranslated region） and rs2297518 （exon 16, missense, Ser608Leu）, using direct sequencing and restriction fragment length polymorphism. The genotypic and allelic frequencies between control and BPH subjects were compared, and the associations among the BPH subjects were analyzed. SNPStats, SNPAnalyzer and HelixTree programmes were used to analyze SNPs. There was no association on SNPs between control and BPH subjects. When BPH subjects were analyzed, there was no association on SNPs between the low and high prostate-specific antigen groups. However, one SNP （rs 10459953, odds ratio [OR] = 0.44, 95% confidence interval [CI] = 0.29-0.65, P 〈 0.0001, in codominant model; OR = 0.23, 95% CI = 0.12-0.46, P 〈 0.0001, in dominant model; and OR = 0.46, 95% CI = 0.24-0.86, P = 0.015, in recessive model） was associated with prostatic volume in BPH. We detected a strong association in genotype frequencies of NOS2 SNP （rs10459953） between subjects with small and large prostatic volume in BPH. The result suggests that NOS2 may be associated with prostatic volume in BPH.

关键词： benign prostatic hyperplasia nitric oxide synthase 2 single nucleotide polymorphism

Poly-gamma-glutamic acid from Bacillus subtilis upregulates pro-inflammatory cytokines while inhibiting NLRP3, NLRC4 and AIM2 inflammasome activation

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Cellular & Molecular Immunology 2018年第2期15卷 111-119页

作者： Huijeong Ahn Seung goo Kang Sung-il Yoon Pyeung-Hyeun kim Doo kim Geun-Shik Lee College of Veterinary Medicine and Institute of Veterinary Science Kangwon National UniversityChuncheon24341GangwonRepublic of Korea Department of Systems Immunology College of Biomedical ScienceKangwon National UniversityChuncheon24341GangwonRepublic of Korea Department of Molecular Bioscience School of Biomedical ScienceKangwon National UniversityChuncheon24341GangwonRepublic of Korea

Poly-gamma-glutamic acid(γ-PGA)is a natural,edible and non-toxic polymer synthesized by Bacillus subtilis and is suggested as a safe biomaterial for the use in hydrogels and vaccine ***,the effect ofγ-PGA on inflammasome activation has not yet been studied in ***,which are intracellular multi-protein complexes,promote acute and chronic inflammation via interleukin-1βor interleukin-18 maturation,and they are known targets for metabolic syndromes and *** this study,we observed thatγ-PGA attenuated NLRP3,NLRC4 and AIM2 inflammasome activation,whereas it upregulated pro-inflammatory cytokine expression in human and murine ***γ-PGA had conflicting effects on cytokine production and maturation,it clearly alleviated the severity of lipopolysaccharide-induced endotoxin shock in an animal ***,we suggestγ-PGA as a candidate to control inflammasome-mediated disorders.

关键词： Cheonggukjang cytokines inflammasome macrophages poly-gamma-glutamate

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

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摩擦:英文版 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)

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

Study on the Wiping Gas Jet in Continuous Galvanizing Line

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Journal of Thermal Science 2011年第3期20卷 242-247页

作者： Yong-Hun Kweon Heuy-dong kim POSCO Technical Research Laboratories 699 Gumho-dong GwangyangJeonnam 545-090 Korea School of Mechanical Engineering Andong National UniversityAndong 760-749 Korea

In the continuous hot-dip galvanizing process, the gas-jet wiping is used to control the coating thickness of moving steel strip. The high speed gas-jet discharged from the nozzle slot impinges on the strip, and at this moment, wipes the liquid coating layer dragged by a moving strip. The coating thickness is generally influenced on the flow characteristics of wiping gas-jet such as the impinging pressure distribution, pressure gradient and shear stress distribution on the surface of strip. The flow characteristics of wiping gas-jet mentioned above depends upon considerably both the process operating conditions such as the nozzle pressure, nozzle-to-strip distance and line speed, and the geometry of gas-jet wiping apparatus such as the height of nozzle slot. In the present study, the effect of the geometry of nozzle on the coating thickness is investigated with the help of a computational fluid dynamics method. The height of nozzle slot is varied in the range of 0.6mm to 1.7mm. A finite volume method (FVM) is employed to solve two-dimensional, steady, compressible Navier-Stokes equations. Based upon the results obtained, the effect of the height of nozzle slot in the gas-jet wiping process is discussed in detail. The computational results show that for a given standoff distance between the nozzle to the strip, the effective height of nozzle slot exists in achieving thinner coating thickness.

关键词： Gas-Jet Wiping Hot-Dip Galvanizing Impact Pressure Coating Thickness

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.

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