• 한국진공학회:학술대회논문집
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• 한국진공학회 1998년도 제14회 학술발표회 논문개요집
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• pp.18-18
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• 1998

F First I will introduce our works how to improve the crystal growth t technique for Rare earth pnictides and chalcogenides. All these substances h have hi양1 vapor pressure and high melting print up to 3$\alpha$)()C. 까len we employ m the tungsten or molybden crucibles and enclose the sample by 빼e welding of m the lid with high current electron beam. We cannot elevate the temperature up t to 3$\alpha$)()C without suitable radiation shield because rate of radiation loss r rapidly increase in such a high temperature regions. There were no good r radiation shield but we discovered that the p-BN could work as an excellent r radiation shield after checking of the many substances. S Secondly I will show several interesting and unusual 뻐ysical properties of obtained crystals under high magnetic field, hi양1 pressure and also i including angle resolve photoemission spectroscopy. I will stress the p properties of the low carrier concentration with strong correlation on C댐, U USb and Yb4As3

• 동의생리병리학회지
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• 제18권1호
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• pp.167-171
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• 2004

This study investigated a HSP70 expression of Puerariae Radix in cerebral ischemia. The global cerebral ischemia was induced by bilateral common carotid arteries occlusion under hypotension (40 mmHg) in Sprague-Dawley rats. After the treatment of Puerariae Radix extract, the heat shock protein 70 (HSP70) expressions were measured immunohistochemically. The upregulation of HSP70 expression in hippocampal regions resulted by cerebral ischemia. Then Puerariae Radix treatment demonstrated significant decrease of HSP70 expressions in CA1 region and dentate gyrus of the hippocampus as compared with control group. These results suggested that Puerariae Radix reveals the neuroprotective effect through the control of noxious stress stimulations to neurons.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.405-410
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• 2007

We present a new global/local analysis with the aid of MLS(Moving Least Square)-based finite elements which can handle an arbitrary number of nodes on every element side. It give a great flexibility in constructing finite element meshes at the specified local regions without remeshing. Compared to other type global/local analysis, it does not require any superimposed mesh or need not solve the equilibrium equation twice as well as shows an excellent accuracy. To demonstrate the performance of proposed scheme, we will show several examples in relation to capturing highly local stress field.

• 한국철도학회논문집
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• 제6권1호
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• pp.21-28
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• 2003

Environment-dependent fatigue life of Cu-Cd alloy wires used as messenger wires was investigated. Tensile test results showed the decrease of tensile strength and elongation of messenger wires by 3.7% and 16.8%, respectively, in used specimens when compared to new ones. Messenger wires used at industrial region for 26 yeras showed 35∼50% decrease in fatigue life, which is partly due to the in stress concentrations by formation of corrosion products at the surface. Single wires showed better fatigue properties than stranded wires, especially at low cycle regions with higher stresses. Stranded wires showed shorter fatigue lives than single wires because of friction between wires by surface contact. Service life of messenger wires was dependent upon the environments which they were exposed to. SO$_2$ and humidity deteriorated the fatigue properties by environmental degradation.

• 한국유체기계학회 논문집
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• 제13권1호
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• pp.17-22
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• 2010

In this paper, numerical study on a mixed-flow pump for irrigation and drainage has been performed based on three-dimensional viscous flow analysis. Reynolds-averaged Navier-Stokes equations with shear stress transport turbulence model are discretized by finite volume approximations and solved by the commercial CFD code ANSYS CFX-11.0. A structured grid system is constructed in the computational domain, which has O-type grids near the blade surfaces and H/J-type grids in other regions. The numerical results were validated with experimental data for the heads and efficiencies at different flow coefficients. The efficiency at the design flow coefficient is evaluated with the variation of two geometric variables related to area of discharge and length of the vane in the diffuser. The results show that efficiency of the mixed-flow pump at the design flow coefficient is improved by the modifications of the geometry.

• 한국안전학회지
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• 제26권6호
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• pp.7-12
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• 2011

In recent years, environmental concerns have been raised on the use of poorly biodegradable fluids in electrical apparatus in regions where spills from leaks and equipment failure could contaminate the surroundings. The newly invented vegetable insulating oil is highly biodegradable and have negligible impact on the environment, human health and the ecosystem. For development of the environmental-friendly pole transformer using vegetable insulating oil, the dielectric constructions of the pole transformer were discussed in this paper. Depending on the dielectric constructions, the AC breakdown characteristics of the Nomex insulating papers and the vegetable insulating oil were studied by simulated electrode systems. Based on the experimental results, the maximum design stress($E_{max}$) for insulation design of the environmental-friendly pole transformer were suggested.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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• pp.279-283
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• 2004

Thermal postbuckling and vibration analyses of functionally graded plates (FG plates) are performed. The nonlinear finite element equation based on the first-order shear deformation plate theory is formulated for the FG plate. The von Karman strain-displacement relation is used to account for the thermal large deflection. The incremental method considering the effect of the initial deflection and the initial stress is adopted for temperature-dependent material properties of functionally graded materials. The numerical result shows characteristics of the thermal postbuckling and vibration of FG plates in the pre- and post- buckled regions.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.256-266
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• 1999

The angled crack which is the simplest and representative case in the mixed mode crack analysis has stimulated the interests of many investigators during past 20 years. In this study the conventional quadratic isoparametric elements were used in all regions except the crack tip zone where triangular singularity elements with 6 nodes were used. The stress intensity factor of K1 and KII were determined respectively by the displacement correlation method. The finite element analysis program in this paper based on maximum energy release rate criteria and the results obtaiend by this program were compared with those calculated from the maximum circumferential tensile criteria and those by Jenq and Shah's experiments of the same geometry and material properties

• 한국표면공학회지
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• 제34권4호
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• pp.289-296
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• 2001

Ni-P electroformed layers were investigated for developing a steam generator tube repair technology in PWRs. The effects of an additive, RPP (Reagent over Pitting Protection) and agitation on mechanical properties and microstructure of the layer were evaluated. The addition of the RPP showed to inhibit the formation of pores, to refine the grain size, and to increase the residual stress in the layer. However, the agitation of the solution during electroforming was observed to increase pores in local regions of the electroformed layer, resulting in decreasing its mechanical properties. The heat treatment of the layer at $343^{\circ}C$ for 1 hr. precipitated the very fine particles of Ni3P in the layer, which inhibited grain growth and increased microhardness.

• Structural Engineering and Mechanics
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• 제83권1호
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• pp.67-77
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• 2022

In this study, frictionless continuous and discontinuous contact problems of a magneto-electro-elastic layer in the presence of the body force were discussed. The layer was indented by a rigid cylindrical insulating punch and supported by a rigid substrate without bond. Applying the Fourier integral transform technique, the general expressions of the problem were derived in the presence of body force. Thanks to the boundary conditions, the singular integral equations were obtained for both the continuous and the discontinuous contact cases. Gauss-Chebyshev integration formulas were used to transform the singular integral equations into a set of nonlinear equations. Contact width under the punch, initial separation distance, critical load, separation regions and contact stress under the punch and between the layer, and substrate were given as a result.