• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.2 s.72
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• pp.195-202
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• 2006

Thin-walled structures are efficiently utilized an automobiles, aircraft, satellite and ship as well as needed light weight simultaneously. This paper presents new shape of automobile hood reinforcement that rotating parts as engine, transmission are protected by thin-walled structures. The automobile hood is concerned about the resonance occurs due to the frequency of the rotating parts. The hood must be designed by supporting the stiffness of design loads and considering the natural frequencies. Hence, it is sustained the stiffness and considered the vibration by resonance. It is deep related to ride. Therefore, the topology, shape and size optimization methods are used to design the automobile hood. Topology technique is applied to determine the layout of a structural component optimum size with maximized natural frequency by volume reduction. In this research, The optimal structure layout of an inner reinforcement of an automobile hood for the natural frequency of a designated mode is obtained by using topology optimization method. The optimum size and the optimum shape are determined by PLBA(Pshenichny-Lim-Belegundu-Arora) algorithm.

• Journal of Korean Association for Spatial Structures
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• v.7 no.3 s.25
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• pp.153-165
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• 2007

Flexible structure uses a material with strong axial stiffness and small bending stiffness as its major structural material so it is very sensitive to initial stiffness. Therefore, the self-formation process which accomplishes a form in the natural world is grasped and it is as well investigated and classified the type of modeling techniques which are available to find the shapes of soft structures. Accordingly, for analysis and design of flexible structure, three-step analysis such as shape analysis, stress-deformation analysis, cutting pattern generation and constructional analysis is required unlike the existing stiff structure. In this study, suggest that minimize the error of side curvatures by the triangle Re-mesh pattern and draw the cutting pattern generation.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.103-107
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• 2005

This study was carried out to examine the prediction of ship's manoeuvrability in initial design stage. New parameter representing basic hull form and stern shape were proposed. Captive model test were carried out to investigate the correlation coefficient between hydrodynamic coefficient and hull parameter. The results showed which parameter are positive correlation with hydrodynamic coefficient. Moreover correlation was examined between sternhull shape and ship's manoeuvrability. These results can be used to predict a ship's manoeuvrability in initial design stage.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6521-6526
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• 2013

Elastic and nonlinear ultimate strength analyses were conducted to examine the effects of the stiffness and slenderness of flat-type stiffeners on ultimate in-plane strengths of a stiffened plate system. Although it is not feasible to consider local buckling in the stiffeners in elastic analysis, it was confirmed that the in-plane strengths of the stiffened plate system can be achieved by antisymmetric buckling mode when a certain level of stiffness in the stiffeners is provided. Nonlinear ultimate strength analysis, in which initial imperfection and residual stress are incorporated, showed that the ultimate strengths are sensitively affected by the mode shapes for initial imperfections. The slenderness limit for flat-type stiffeners in KHBDC (Korean Highway Bridge Design Code) was evaluated as conservative compared to the analysis results.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.306-306
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• 2021

현재 도시침수는 외수에 의한 침수보다 국지성 호우 등 홍수방어 시설의 설계빈도 이상의 강우 발생으로 내수에 의한 침수피해가 증가하고 있다. 국지성 호우의 증가로 하천지대 및 저지대로의 유출량이 증가하고 있으며, 우수관거의 노후화 및 통수능 부족으로 침수피해가 증가하는 실정이다. 따라서 홍수방어를 위한 다양한 대책들이 이루어지고 있으나 하수관거 교체 및 대규모의 우수유출저감시설은 막대한 예산과 부지가 소모되므로 대도시에서는 이러한 홍수방어 대책들이 시행되기 어려운 실정이다. 따라서 본 연구에서는 기존의 도로 배수시설에서 도로 표면 유출수의 수로역할을 하던 측구부를 저류시설로 활용하여 대규모의 부지와 큰 예산이 소요되지 않는 측구 저류시스템을 개발하였다. 측구 저류시설의 관련 특성인자 분석을 위하여 세장형, 중간형, 집중형 등 3가지 형상의 가상유역을 대상유역으로 선정하여 측구 저류시설 설치 및 유역 특성인자의 변화에 따른 관계를 분석하였다. 측구 저류시설 설치 위치에 따른 유출저감효과 분석을 위하여 전체 유역면적에 대한 저류시설 상류부 면적의 비를 변화시키면서 분석을 수행하였으며, 매개변수 분석 및 관계식을 도출하였다. 또한 유역형상에 따른 유출구 첨두유량을 분석하였으며, 그 결과를 바탕으로 유역 특성인자 변화에 따른 민감도를 분석하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.10
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• pp.969-978
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• 2008

In a linear cascade experimental apparatus, when it adopts only few blades as well as satisfies the periodic condition between blades, it gives several advantages in experiment. In this study, wall design on a cascade experimental apparatus is conducted to obtain the periodic condition on two blades installed within a passage of which the width is double pitch. The Mach number difference on the blade surface obtained with the periodic and wall condition is chosen as an objective function, and twelve design variables which are related to the wall shape are selected. A wall shape is designed using a gradient-based optimization method. Adjustment of range and weighting function are applied to calculate the objective function to avoid unrealistic evaluation of the objective function. By applying these methods, the computed results show same flow structures obtained with the periodic condition.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.3
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• pp.173-180
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• 2007

Oscillating wave amplitude in a bottom-mounted OWC chamber designed for wave energy converter is investigated by applying characteristic wave conditions in Korean coastal water. The effects of shape parameters of OWC chamber in a view of wave energy absorbing capability are analyzed. Both experimental and numerical approaches are adopted and their results are compared to optimize the shape parameters which can result in a maximum power production under given wave distribution. The experiment was carried out in a wave flume under 2-D assumption of OWC chamber. The numerical scheme employed a hybrid Green integral equation which adopts the Rankine Green function inside chamber to take account of fluctuating air pressure, while it uses the Kelvin Green function in outer domain. Air duct diameter, chamber width, and submerged depths of front skirt and back wall of chamber changes the magnitude and peak frequency of wave absorption significantly.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2211-2219
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• 2000

Near net shape forming of 316L stainless steel powder was investigated under hot isostatic pressing. To simulate densification and deformation of a powder compact in a container during hot isostatic pressing, the constitutive model of Abouaf and co-workers was implemented into a finite element analysis. An optimal design technique based on the design sensitivity was applied to the container design during hot isostatic pressing. The optimal shape of the container was predicted from the desired final shape of a powder compact by iterative calculations. Experimental data of 316L stainless steel powder showed that the optimally designed container allowed precise forming of the desired powder compact during hot isostatic pressing.

• Journal of Korea Water Resources Association
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• v.37 no.4
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• pp.293-304
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• 2004

Sedimentation basin plays an important role in urban water treatment, and there are many complicated phenomena which need to be understood for efficient design and control of it. Especially, the study on the improvement of settling efficiency is required. In this study, commercial CFD (Computational Fluid Dynamics) program, FLUENT, and particle tracking method were used to simulate the flow in sedimentation basin, and to predict the settling efficiency. Computational domain of real scale was made, and detail factors such as porous wall, and outlet trough were considered instead of being simplified. The simulation results were compared with the experimental data to calibrate the parameters of particle tracking method. Sensitivity analysis showed that the particle diameter had more significant effects on settling efficiency than the particle density. The computation results gave the best agreements with the experimental data, when the value of particle diameter was 26.5 ${\mu}{\textrm}{m}$.

• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.15-18
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• 1990

In this paper, in order to optimize the shape of electrode to achieve prescribed electric field intensity distribution along the surface of electrode, sensitivity analysis based on finite element method is proposed. The objective function of this problem is the difference of calculated electric field intensity at given design and prescribed electric field intensity. So, the problem is to find the shape of electrode to minimize the objective function defined above. The result of numerical example shows that maximum electric field error is about 0.1% and the usefulness of this shape optimal design procedure.