• Proceeding of EDISON Challenge
• /
• 2017.03a
• /
• pp.216-225
• /
• 2017

제조 기술의 고도화가 이루어진 현 시점에서, 제품의 설계방식도 단순구조설계가 아닌 최적설계를 통해 제품의 경제성과 안정성을 동시에 획득하고 있다. 본 논문에서는 인장, 압축, 비틀림과 같은 다양한 힘을 받는 자전거의 크랭크 암에 대해 최적 설계를 진행하였고, EDISON의 Plastic Deformation with Damage Mechanism Analysis SW 프로그램을 통해 유한 요소 해석을 수행했다. 해석은 크랭크암 내부에 응력 값이 가장 높은 $90^{\circ}$를 경계조건으로 표면 응력을 고려한 구조, 내부 응력을 고려한 구조, 트러스를 적용한 구조와 MATLAB을 통해 위상최적화 후 추가적으로 형상을 최적화한 구조를 설계했다. 끝으로 경제성과 안정성을 판단하는 기준으로 각각의 질량 대비 강성을 확인하여 최적의 형상을 제시하였다.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.28 no.4
• /
• pp.425-431
• /
• 2015

Based on a bond-based peridynamics theory for dynamic crack propagation problems, this paper presents a design sensitivity analysis and optimization method. Peridynamics has a peculiar advantage over the existing continuum theory in the mathematical modelling of problems where discontinuities arise. For the design optimization of the crack propagation problems, a non-shape design sensitivity is derived using the adjoint variable method. The obtained adjoint sensitivity of displacement and strain energy turns out to be very accurate and efficient compared to the finite different sensitivity. The obtained design sensitivities are futher utilized to optimally control the position of bifurcation point in the design optimization of crack propagation in a plate under tension. A numerical experiment demonstrates that the optimal distribution of material density could delay the position of bifurcation.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2010.04a
• /
• pp.508-511
• /
• 2010

본 논문에서는 정상상태 유체-구조 연성문제를 연속체 기반으로 정식화하고 유한요소법을 이용하여 완전 연성된 해를 구하였다. 대 변형을 고려하기 위하여 토탈 라그란지안 정식화를 사용하였으며 유체 및 구조의 비선형성이 고려되었다. 유체와 구조 영역의 형상을 NURBS 곡면을 이용하여 매개화하여 표현하였으며, 형상 최적화를 위해 효율적인 설계민감도 해석법인 애조인 기법을 이용하여 압력, 속도, 변위 등에 대한 설계민감도를 구하였다. 이를 이용하여 최소 컴플라이언스를 갖게 하는 구조물 내부의 유체영역의 설계 등의 수치예제를 통하여 개발된 방법론의 타당성을 확인하였다.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.32 no.6
• /
• pp.383-390
• /
• 2019

A helideck is one of the essential structures in offshore platforms for the transportation of goods and operating personnel between land and offshore sites. As such, it should be carefully designed and installed for the safety of the offshore platform. In this study, a structural design optimization method for a lightweight offshore helideck is developed based on a genetic algorithm and an attainable design set concept. A helideck consists of several types of structural members such as plates, girders, stiffeners, trusses, and support elements, and the dimensions of these members are typically pre-defined by manufacturers. Therefore, design sets are defined by collecting the standard section data for these members from the American Institute of Steel Construction (AISC), and integer section labels are assigned as design variables in the genetic algorithm. The objective is to minimize the total weight of the offshore helideck while satisfying the maximum allowable stress criterion under various loading conditions including self-weight, wind direction, landing position, and landing condition. In addition, the unity check process is also utilized for additional verification of structural safety against buckling failure of the helideck.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.9 no.1
• /
• pp.111-119
• /
• 2005

This study presents continuous and discrete optimum design algorithm and computer programs for unbraced and braced steel frame structures under earthquake loads. The program, which is avaliable to perform structural analysis and optimum design, continuous and discrete, simultaneously is developed. And the program adopts various braced types, Untraced, Z-braced(V), Z-braced(inverse-V), X-braced(A), X-braced(B), X-braced(C) and K-braced, in steel structures with static loads and seismic effects. The objectives in this optimization are to minimize the total weight of steel, and design variables, based on the ultimate strength requirements of AISC-ASD specifications, the serviceability requirements and allowable story drift requirements of ATC-3-06, and various constraints. The purpose is to present proper braced type for seismic effects by comparing and analysing results of various cases.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2009.04a
• /
• pp.404-407
• /
• 2009

ILM(incremental launching method) 교량공법은 품질확보에 효과적인 프리스트레스 콘크리트 교량공법으로 인정받고 있다. 이 공법에 의해 시공되는 교량의 상부단면은 시공 중에 지간의 중앙부와 지점부에 일시적이나마 모두 위치하게 된다. 앞선 연구에서 압출 중인 ILM 교량의 상부단면에 발생하는 단면력의 변화를 간편하게 예측할 수 있는 해석식을 개발하였다. 그리고 개발된 해석식을 이용하여 매개변수들의 변화에 따른 상호작용의 영향을 분석하여 많은 대안들이 검토되는 초기 설계단계에 유용한 설계식도 제안하였다. 본 논문에서는 압출중인 ILM 교량의 상부단면에 발생하는 단면력을 효과적으로 제어위해 유도된 해석식을 이용하여 현재 국내 공용중인 ILM 교량의 설계수준을 검토하였고, 상부구조의 최적설계를 위한 방안을 제시하였다.

• Journal of Navigation and Port Research
• /
• v.30 no.1 s.107
• /
• pp.105-111
• /
• 2006

A LMTT (Linear Motor-based Transfer Technology) is a horizontal transfer system for the yard automation This system is based on PMLSM (Permanent Magnetic Linear Synchronous Motor) that consists of stator modules on the rail and shuttle car. In this research, the kriging interpolation method using sequential sampling is utilized to find the optimum design of a mover in LMTT. The design variables are considered as the transverse, longitudinal and wheel beam's thicknesses. The objective function is set up as weight, while the constant functions are set up as the stresses generated by four loading conditions. The optimum results obtained by the suggested method are compared with those determined by the GENESIS.

• Composites Research
• /
• v.25 no.2
• /
• pp.54-61
• /
• 2012

In this study, a specific structural design procedure for 2 MW class glass/epoxy composite wind turbine system towers is newly proposed through load case study, trade-off study, optimal structural design and structural analysis. Optimal tower design is very important because its cost is about 20% of the wind turbine system's cost. In the structural design of the tower, three kinds of loads such as wind load, blades, nacelle and tower weight and blade aerodynamic drag load should be considered. Initial structural design is carried out using the netting rule and the rule of mixture. Then the structural safety and stability are confirmed using a commercial finite element code, MSC NASTRAN/PATRAN. The finally proposed tower configuration meets the tower design requirements.

• The Journal of the Acoustical Society of Korea
• /
• v.17 no.4
• /
• pp.30-37
• /
• 1998

본 논문은 중공형 층상 복합체 멘드릴(mandrel)을 이용하여 기본 공진주파수가 15kHz이상이고, 우수한 감도 특성을 지닌 광섬유 하이드로폰의 최적 구조를 설계하는 것에 관한 것이다. 유한요소법을 이용하여 Al/foraming 및 Nylon/foaming층상 복합체의 공지주 파수를 분석하여 설계 변수의 범위를 결정하였고, 멘드릴 형상에 따른 광음향 감도 특성을 분석하여 최적구조를 결정하였다. 그 결과로 멘드릴의 외경이 감소할수록, 길이가 증가할수 록 감도가 향상되었다. AL 멘드릴의 경우, 내경/외경 비가 낮을수록, Nylon멘드릴의 경우 내경/외경 비가 높을수록 감도 증가를 위하여 효율적이다. 그리고 결정된 최적구조의 Al/foaming 및 Nylon/foaming멘드릴을 사용한 광섬유 하이드로폰의 감도는 각각 1rad./Pa 대비 약 82dB 및 85.7dB 정도 이었고, Al층상 복합체 보다는 Nylon층상 복합체를 이용하는 것이 고 감도의 광섬유 하이드로폰을 제조하는데 유리함을 알 수 있었다.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.14 no.4
• /
• pp.505-513
• /
• 2001

In this study, an optimum design algorithm using efficient reanalysis is proposed for seismic design of Reinforced Concrete (RC) piers. The proposed algorithm for optimization of RC piers is based on efficient reanalysis technique. Considering structural behavior of RC piers, the other approximation technique such as artificial constraint deletion is introduced to increase the efficiency of optimization. The efficiency and robustness of the proposed algorithm including the proposed reanalysis technique is demonstrated by comparing it with a conventional optimization algorithm. A few of design examples are optimized to show the applicability of the proposed algorithm.