• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.6
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• pp.477-485
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• 2012

Geometric configurations such as hull shape, wall thickness, stiffener layout, and type of construction materials are the key factors influencing the structural performance of pressure hulls. Traditional theoretical approach provides quick and acceptable solutions for the design of pressure hulls within specific geometric configuration and material. In this paper, alternative approaches that can be used to obtain optimal geometric shape, wall thickness, construction material configuration and stiffener layout of a pressure hull are presented. CAE(Computer Aided Engineering) based design optimization tools are utilized in order to obtain the required structural responses and optimal design parameters. Optimal elliptical meridional profile is determined for a cylindrical pressure hull design using metamodel-based optimization technique implemented in a fully-integrated parametric modeler-CAE platform in ANSYS. While the optimal composite laminate layup and the design of ring stiffener for a thin-walled pressure hull are obtained using gradient-based optimization method in OptiStruct. It is noted that the proposed alternative approaches are potentially effective for pressure hull design.

• Composites Research
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• v.25 no.6
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• pp.224-229
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• 2012

The structural performance is degraded in case of embedding the array antenna for reconnaissance and surveillance into the wing skin structures. In this paper, the optimal design for the thickness of composite hat-shaped stiffener which is reinforced embedded array antenna on the simplified composite wing box was conducted. To select the basic shape of hat-shaped stiffener, structural analysis was carry out using the commercial finite element analysis program while changing the web slope and flange length of hat-shaped stiffener. The optimal thickness of the composite hat-shaped stiffeners was determined by using commercial optimization program such as VisualDOC and commercial FEA program with considering stresses and buckling constraints.

• Journal of the KSME
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• v.31 no.1
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• pp.34-42
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• 1991

복잡한 형상의 서지 탱크를 CAEDS의 GEOMOD를 이용하여 내부의 리보까지 포함한 용기를 모델링하였으며, 설계 부피를 검사하고 GEOMOD와 GFEM 사이의 직접 데이터 교환을 통하여 구조 해석에 필요한 유한요소를 만들었다. 유한요소법에 최적화 이론을 적용하여 서지탱크의 두께 변화에 따른 응력의 설계 민감도를 구하였으며, 민감도를 근거로 보강 위치 및 국부적인 용기의 두께를 결정하였다. 유한요소법 프로그램(IFES, GFEM)과 솔리드 모델러(GEOMOD), 그리고 최적화 기법(IFES-Optimization)을 모두 통합하여, 최적 설계를 수행함으로써 반복되는 실험에 의한 시간과 경비를 줄임과 동시에 신뢰성 있는 설계방법 및 방향을 제시하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.35-35
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• 1999

KSTAR NBI 장치의 진공용기와 Grid에 대하여 열 및 구조해석을 ANSYS 코드를 이용하여 수행하였다. 진공용기의 경우 진공용기 지지구조물을 최적화할 수 있는 구조형상에 관하여 연구하였고, Grid의 경우 Grid 형상 및 재료 특성에 중점을 두어 연구하였다. 또한 Electron Dump의 냉각수로의 위치 및 형상, 크기를 최적화시켰다. 이번 각 구조물의 최적화 연구에서 특히 중점을 둔 사항은 재료와 관련된 경제성이다. 진공용기에서 가장 문제가 되는 것은 용기의 크기에 따른 변형도이다. 진공용기의 Cryo-sorption 패널 배기속도는 30000 I/sec 이상이고, 진공 용기의 운전시 진공도는 5$\times$10-7Torr 이하이다. 구조해석의 결과로부터 폭 3m$\times$높이 4,m$\times$길이 5m, 두께 2cm인 진공용기는 대기압 하에서 7cm의 변형도를 갖는다. 변형을 최소화하기 위해 T형 보강구조물을 부착시켰을 때 변형도가 1cm 이하로 감소함을 볼 수 있었다. [그림1] 장시간 운전시 Grid에 미치는 열부하에 의한 영향을 연구하였다. 열해석 결과와 경제성, 가공성을 동시에 고려할 때 Grid의 재질로 무산소동이 적합함을 알 수 있었다. 한편, NBI 장치에서 열부하가 최대인 곳은 이온원의 Electron Dump 부분으로 중심부분에서 20MW/m2이다. 열부하를 효과적으로 소산시키기 위해 Electron dump 의 중심부분 모양을 깔대기 모양으로 만들어 Dump 뒷부분의 자석에 미치는 영향을 최소화 시켰다. 이 때 냉각수록의 냉각수 흐름속도 4.5m/sec이고, 자석의 최대 온도는 15$0^{\circ}C$로써 자석의 기본성질을 일어버리지 않는 허용범위 내에 들어옴을 알 수 있었다. 자석의 온도는 10초 동안 급격히 상승하였고, 100초 이후에 포항상태에 도달하였다 [그림2]

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.5
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• pp.501-507
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• 2009

By using topology and shape optimization, a theoretically optimum FRP deck was proposed. Firstly, a topologically optimal shape, truss-like structure without hinges, was found. A truss-shape frame is the most ideal structure when subjected to a concentrated force at the center of simply supported beam. An armature was found at the point joining horizontal chord and diagonal chord, which was used as a new design variable. Secondly, optimum value of each variable was decided through shape optimization using genetic algorithm. To compare it with existing commercial FRP decks, shape optimization was performed by fixing the height of FRP decks. To verify the performance of the FRP deck proposed in this study, a finite element analysis was performed. As a result, it satisfies serviceability and safety guide lines of FRP decks.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.3
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• pp.277-286
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• 2001

Among the ULSAB methods for the lightweight automobile body, Tailor Welded Blank(TWB) is adopted and the design process is developed for the existing component. Topology optimization conducted to find the distribution of the variable thickness. The number of parts and the welding lines are determined from it. In the detail design, size optimization is carried out to find the optimum thickness of each part and then, the final parting lines are tuned by shape optimization. A commercial optimization software GENESIS is utilized for the optimization processes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.230-236
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• 2020

A trash screen is installed in front of the inflow channel of a drainage pumping station, sewage treatment plant, and a power plant to block floating contaminants. The bottleneck phenomenon, which decreases the water inflow, causes damage to the damper as a result of clogging in between the screen if string type obstacles are not removed. In this paper, the apron was removed, and the screen was expanded, to prevent breakage of the bottleneck phenomenon and string type obstacles. This was designed using an extended rake by adding an inner rake in between the screen interspace to remove the bottleneck phenomenon and string type obstacles. To design the inner rake that satisfies the allowable stresses of the existing damper rake, the experiment points were determined according to the experimental design method using the inner rake vertical length and the thickness of the reinforced section as parameters. The use of the ANSYS static structural module and statistical analysis tool R software gives the optimized shape according to the response surface method. The relative error between the response surface analysis results and the simulation results was 1.63% of the determined optimal design-point rake length of 210.2 mm and the reinforcement section thickness of 2 mm. Through empirical experiments, a test rake was constructed to the actual size, and approximately 97% of the bottleneck phenomenon and string type obstacles could be removed.