• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.1919-1932
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• 1991

Experimental studies are conducted to investigate the Flow-Induced Vibration mechanism for cantilever plate model with the angle of attack (.alpha.=10.deg., 20.deg., 30.deg.). Research is divided into two parts. First, the flow fields around two dimensional flat plate model are investigated using LDV system. Second, the vortex shedding frequency and response spectra of cantilever plate are obtained experimentally using gap sensor and hot wire anemometer. Finite element method program was used in order to predict the flow field and pressure field around thin flat plate. And some predicted results were compared with the experimental data. The aspect ration of test model is d/t=25 (d; width, t; thickness). From the measurement of the flow field it was found that in the case of small inclined (.alpha.=10.deg., 20.deg.) relatively, the separated boundary layer at sharp leading edge developed smoothly downstream. With increasing the angle of attack of the plate, stagnation region was appeared on the back side of the plate and separated boundary layer was extended downstream. These trends are a good agreement with the computational results. It was found by analysis of response spectra of cantilever plate that the influences of vortex shedding frequency were important at the large of attack (.alpha.=30.deg.), and two peak values appear in entire test model at 24Hz, 150Hz.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.8
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• pp.12-19
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• 2004

Low-speed gas flows around a micro-scale flat plate are investigated using a kinetic theory analysis. The Boltzmann equation simplified by a collision model is solved by means of a finite difference approximation with the Discrete Ordinate method. Calculations are made for flows around a 5% flat plate with a finite length of 20 microns. The results are compared with those from the Information Preservation method and a continuum approach with slip boundary conditions. It is shown that three different approaches predict a similar basic flow patterns, while the results from the present method are more accurate than those from the other two methods in details.

• Journal of the Korean Vacuum Society
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• v.17 no.6
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• pp.487-494
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• 2008

The numerical simulation of point-to-plane discharge of nitrogen at medium pressure has been achieved by a quasi-2d numerical model. In the model, we calculate the distributions of electric charges which are varying as temporal and space and determine the electric field depending on space charge distribution by solving Poisson's equation. The continuity equations are treated numerically by using FCT (Flux-Corrected Transport) Algorithm and FEM (Finite Element Method). The numerical simulation results make us to understand the physical characteristics of nitrogen discharge at 50 torr. The comparison with experimental results[1] shows a good qualitative agreement.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1475_1476
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• 2009

본 논문에서는 스트리머 방전에 대한 연구의 일환으로 전자사태의 발생과정 및 절연파괴현상을 2차원 유한요소법을 이용하여 해석하였다. 평행 평판 전극을 모델로 도입하고 전자밀도에 대한 경계조건을 변화시켜 각각 시뮬레이션을 통하여 신뢰성 있는 결과를 도출하였다.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2006.10a
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• pp.126-131
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• 2006

광학적으로 우수한 특성을 지닌 유리는 온도에 민감한 대표적 점탄성 재료로서 역학적 열적 거동에 대한 충분한 이해와 해석이 평판 영상장치 제조공정에서 불량의 원인을 제거하고 공정 최적화를 하는데 중요하다. 본 연구에서는 평판 영상장치 제조공정에서 발생하는 문제들 중 하나인 열수축 현상(열처리 공정 전후 유리의 치수가 변하는 현상)을 소다라임 유리에 대해서 전산모사 하였으며, 유리의 구성방정식으로 구조이완 모델을 이용하였다.

• Computational Structural Engineering
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• v.9 no.3
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• pp.199-207
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• 1996

When an initially straight thin cylinder is bent, there is a tendency for the cross section to flatten. This phenomenon was investigated by L.G. Brazier in 1927 and is called "Brazier Effect" or "Brazier Theory". The main characteristic is the reduction of carrying capacity due to the decrease of bending stiffness by shortening of thickness with the increase of external load. And the relationship of curvature-bending moment becomes a soft spring type as shown in Fig.2. In this paper, the Brazier theory on plate type structures is investigated from the following view points : (1) What is the Brazier effect? (2) the reason of the occurrence of the Brazier effect in plate type structures by using beam model and (3) factors which cause the brazier effect.

• Journal of Korean Association for Spatial Structures
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• v.5 no.3 s.17
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• pp.65-74
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• 2005

An analytical model was developed to investigate the flexural behavior of a pultruded fiber-reinforced plastic deck of rectangular unit module. The model is based on first-order shea. deformable plate theory (FSDT), and capable of predicting deflection of the deck of arbitrary laminate stacking sequences. To formulate tile problem, two-dimensional plate finite element method is employed. Numerical results are obtained for FRP decks under uniformly-distributed loading, addressing the effects of fiber angle and span-to-height ratio. It is found that the present analytical model is accurate and efficient for solving flexural behavior of FRP decks. Also, as the height of FRP deck plate is higher, the necessity of higher order Shear deformable plate theory(HSDT) is announced, not the FSDT in the plate analysis theory.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.5
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• pp.56-61
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• 2002

Experimental flutter test for a flat plate wing is performed and the flutter analysis methods are verified by comparing with the experimental results. Wing model and experimental equipment are established in the subsonic wind-tunnel. From the response of the wing, the flutter speed is estimated by using the system identification technique. MSC/NASTRAN, V-g method and root-locus method are used for the flutter analysis of the wing. The computed flutter speed is compared with the estimated one from the experiment, and they show good agreement. Wing model in the present study can be used as a benchmark model for the flutter analysis.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.3
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• pp.610-616
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• 1990

The fracture mechanics analysis of surface cracks in plates and cylindrical geometries is important in the integrity evaluation of flawed structural components. The objective of this paper is, thus, to numerically investigate an interaction effect of two surface cracks in plate and cylindrical geometries. The effect of crack spacing on the magnitude of the stress intensity factor(K) is investigated using the line-spring model. For the case of a finite plate under uniaxial loading, the effect of crack spacing on the K values is negligible. However, for the case of a cylinder under moderate internal pressure, a significant increase in K values is observed at the deepest point of the surface crack.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.5
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• pp.453-460
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• 2013

The surface roughness and heat transfer enhancement devices are known to increase the performance of a flat plate soar collector. This study includes the experiments on the effect of the several heat transfer enhancement devices inserted in duct to simulate the flat-plate solar collector. Experiment was basically at a constant heat flux on the upper duct wall. Inserted heat transfer enhancement devices are Chamfered rib $10^{\circ}$, Chamfered rib $20^{\circ}$, Rib & Groove and Rib & Dimple. Reynolds number is in the range of 2,300 to 22,000 which corresponds to turbulent regime. With the heat transfer enhancement devices, heat transfer would increase by the secondary flow and the increase of the heat transfer area. Pressure drop also increases with the insertion of the enhancement devices. Rib & Dimple model is the best in heat transfer enhancement, however, Chamfered rib $10^{\circ}$ model is the lowest in the pressure drop. Considering the heat transfer enhancement simultaneously with low pressure drop increase, performance factor was the best for the Chamfered rib $10^{\circ}$.