• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.30 no.4
• /
• pp.313-318
• /
• 2017

This study performs the structural analysis and the optimum design of a vibrating metal damper to absorb vibration energy. Unlike other dampers such as rubber bearing, friction or viscose dampers, the present vibrating metal damper utilizes the plastic deformation of a steel and its associated hysteresis phenomenon to reduce vibrations of structures. To optimize this vibrating metal damper, it is important to obtain plastic deformation through the damper. To achieve this, the shape optimization method is developed and applied to find out optimal envelopes of the metal damper. Depending on the parameterization scheme, some novel optimal shapes can be found.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2003.04a
• /
• pp.335-347
• /
• 2003

본 논문에서는 설계 하중에 지배되는 구조물에 있어서, 입력 파라미터들의 불확실성을 표준편차와 패턴의 변동, 두 차원에서 접근, 처리할 수 있는 방안을 제시하기 위해서 구조물에 입력으로 작용하는 하중 패턴의 결정과 구조물의 형상의 진화를 동시에 고려할 수 있는 Co-Evolutionary Structural Design framework라 명명한 새로운 구조 설계 방식을 개발하였다. 공학자의 직관과 경험 의존적인 하중을 대상으로 최적화된 구조물은, 성능에 완벽한 안전을 보장해 줄 수 없으며, 이에 관한 문제를 해결하기 위해서 주어진 상황 속에서 다양한 하중이 작용하더라도 안전할 수 있는 구조물의 설계 방식에 관해서 설명한다. 본 프레임워크는 연성을 가지는 두 Disciplinary Modules, 즉 구조 형상설계와 하중설계로 이루어지며 하중에 관한 DB로 연결되어 순차적인 MDO 설계과정을 거치게 된다. 두 Discipline은 설계과정을 거치면서 상호 견제의 틀 속에서 진화하며 기존 방식과 달리 극한 하중 패턴을 스스로 찾아서 설계 반영하는 특징을 가진다. 본 접근 방식의 유용성을 평가하기 위해서 10-bar truss 구조물과 Jacket-Type 구조물로 테스트해 보았다.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.34 no.4
• /
• pp.1053-1063
• /
• 2014

This study presents a sustainable design method that optimizes the embodied energy of concrete beam based on the concept of sustainable development that effectively utilizes natural resource and energy within the range that our succeeding generation can afford to utilize. In order to get the flexural strength carrying the ultimate load, concrete beam sections are designed by optimization that consists of the embodied energy as a objective function and the requirements of design code as constrained conditions. The sustainable design can be used to minimize the embodied energy consumed in material production, construction, operation, demolition of the infrastructure. As a result of comparison of the cost and the embodied energy optimizations based on practical beam sections, it is shown that 20% embodied energy saving and 35% $CO_2$ emission saving are achieved by sacrificing 10% cost increase. The sustainable design method provides a new effective methodology that manages the strength design concept based on cost minimization together with economic feasibility and sustainability. In addition, the method is expected to be applied to more various structural design practices.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.35 no.11
• /
• pp.973-982
• /
• 2007

In this paper, optimal design framework is developed by automatic mesh generation and PSO(Particle Swarm Optimization) algorithm based on parallel computing environment and applied to structural optimal design of satellite adapter module. By applying automatic mesh generation, it became possible to change the structural shape of adapter module. PSO algorithm was merged with parallel computing environment and for maximizing a computing performance, asynchronous PSO algorithm was developed and could reduce the computing time of optimization process. As constraint conditions, eigen-frequency and maximum stress was considered. Finally using optimal design framework, weight reduction of satellite adapter module is derived with satisfaction of structural safety.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.3
• /
• pp.229-237
• /
• 2008

In this research, a MDO(multi-disciplinary design optimization) framework, which integrates aerodynamic and structural analysis to design an aircraft wing, is constructed. Whole optimization process is automated by a parametric-modeling approach. A CFD mesh is generated automatically from parametric modeling of CATIA and Gridgen followed by automatic flow analysis using Fluent. Finite element mesh is generated automatically by parametric method of MSC.Patran PCL. Aerodynamic load is transferred to Finite element model by the volume spline method. RSM(Response Surface Method) is applied for optimization, which helps to achieve global optimum. As the design problem to test the current MDO framework, a wing weight minimization with constraints of lift-drag ratio and deflection of the wing is selected. Aspect ratio, taper ratio and sweepback angle are defined as design variables. The optimization result demonstrates the successful construction of the MDO framework.

• Computational Structural Engineering
• /
• v.11 no.3
• /
• pp.213-228
• /
• 1998

구조설계 과정에서 설계대안을 효율적으로 생성하여 평가하면서, 특히 다목적 환경 속에서 최적구조의 위상과 부재의 치수까지 동시에 결정할 수 있는 새로운 방식을 제시하고자 한다. 설계자가 설계대안을 생성하기 위해 설계자의 경험과 노하우를 체계적으로 구축해 놓고 이를 적절한 시기에 활용할 수 있게 하는 방법으로는 인공지능 기술의 하나인 사례기반 추론 기법을 사용하였다. 이와 더불어, 설계대안들 간의 효율적인 비교와 평가를 위해서 구조물의 계층적인 면을 고려한 새로운 유전적인 표현법을 개발하였다. 여기에 기존의 유전적 표현법을 변경시켜 생긴 여분의 효과와 계층적인 특징을 가지는 Structured Genetic Algorithm(StrGA)를 변형시켜서 사례기반 추론에 의해 생성된 설계대안들을 표현하였다. 일반적인 구조설계 과정에서는 구조물을 평가하는 기준이 여러 개가 존재하므로, 모든 대안들을 동시에 최적화 하는 과정에 Multicriteria Optimization for Genetic Algorithm(MOGA)를 병합하였다. 본 논문에서는 인공지능 기술을 이용하여 구조물의 위상설계를 할 수 있는 새로운 방법을 제안하여 그 유용성을 truss 설계문제에 대해 검토하였다.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.15 no.4
• /
• pp.591-598
• /
• 2002

In the ship structural design, the material cost of hull weight and the overall cost of construction processes should be minimized considering safety and reliability. In the past, minimum weight design has been mainly focused on reducing material cost and increasing dead weight reflect the interests of a ship's owner. But, in the past experience, the minimum weight design has been inevitably lead to increasing the construction cost. Therefore, it is necessary that the designer of ship structure should consider both structural weight and construction cost. In this point of view, multi-objective optimization technique is proposed to design the ship structure in this study. According to the proposed algorithm, the results of optimization were compared to the structural design of actual VLCC(Very Large Crude Oil Carrier). Objective functions were weight cost and construction cost of VLCC, and ES(Evolution Strategies), one of the stochastic search methods, was used as an optimization solver. For the scantlings of members and the estimations of objectives, classification rule was adopted for the longitudinal members, and the direct calculation method, GSDM(Generalized Slope Deflection Method), lot the transverse members. To choose the most economical design point among the results of Pareto optimal set, RFR(Required Freight Rate) was evaluated for each Pareto point, and compared to actual ship.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.6
• /
• pp.26-32
• /
• 2016

Usually, there are many uncertainties regarding the error of an assumed load, material properties, member size, and structure analysis in a structure, and it may have a direct influence on the qualities of optimal design of structures. Probabilistic analysis has developed rapidly into a desirable process and structural reliability analysis is an increasingly important tool that assists engineers to consider uncertainties during the design, construction and life of a structure to calculate its probability of failure. This study deals with the applications of two optimization techniques to solve the reliability-based optimization problem of structures. The reliability-based optimization problem was formulated as a minimization of the structural volume subject to the constraints on the values of componential reliability index determined by the AFOSM approach. This presented method may be a useful tool for the reliability-based design optimization of structures.

• Journal of Navigation and Port Research
• /
• v.32 no.3
• /
• pp.223-228
• /
• 2008

As most of small fishing boats made of FRP have been constructed by experience in Korea, some structural safety problems have been occurred occasionally. To improve the structural strength and reduce the costs for construction and operation, optimum design for small fishing boat was carried out in this study. The weight of fishing boat and the main dimensions of structural members are chosen as objective function and design variables, respectively. By the combination of global and local search methods, a hybrid optimization algorithm was developed to escape the local minima and reduce CPU time in analysis procedure, and finite element analysis was performed to determine the constraint parameters at each iteration step in optimization loop. Optimization results were compared with the real existing fishing boat, and the effects of optimum design were examined from points of view; structural strength, material cost, etc.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.11
• /
• pp.1603-1611
• /
• 2010

The comparative study of regression-model-based approximate optimization techniques used in the strength design of an automotive knuckle component that will be under bump and brake loading conditions is carried out. The design problem is formulated such that the cross-sectional sizing variables are determined by minimizing the weight of the knuckle component that is subjected to stresses, deformations, and vibration frequency constraints. The techniques used in the comparative study are sequential approximate optimization (SAO), sequential two-point diagonal quadratic approximate optimization (STDQAO), and approximate optimization based on enhanced moving least squares method (MLSM), such as CF (constraint feasible)-MLSM and Post-MLSM. Commercial process integration and design optimization (PIDO) tools are utilized for the application of SAO and STDQAO. The enhanced MLSM-based approximate optimization techniques are newly developed to ensure constraint feasibility. The results of the approximate optimization techniques are compared with those of actual non-approximate optimization to evaluate their numerical performances.