• 한국생산제조학회지
• /
• 제19권4호
• /
• pp.469-475
• /
• 2010

The objective of this study is to integrate reliability analysis into shape optimization problem using the evolutionary structural optimization (ESO) in the application example. Reliability-based shape optimization is formulated as volume minimization problem with probabilistic stress constraint under minimization max. von Mises stress and allow stress. Young's modulus, external load and thickness are considered as uncertain variables. In order to compute reliability index, four methods, i.e., reliability index approach (RIA), performance measure approach (PMA), single-loop singlevector (SLSV) and adaptive-loop (ADL), are used. Reliability-based shape optimization design process is conducted to obtain optimal shape satisfying max. von Mises stress and reliability index constraints with the above four methods, and then each result is compared with respect to numerical stability and computing time.

• 대한기계학회논문집A
• /
• 제30권8호
• /
• pp.889-896
• /
• 2006

The concept of reliability has been applied to the topology optimization based on a reliability index approach or a performance measure approach. Since these approaches, called double-loop single vector approach, require the nested optimization problem to obtain the most probable point in the probabilistic design domain, the time for the entire process makes the practical use infeasible. In this work, new reliability-based topology optimization method is proposed by utilizing single-loop single-vector approach, which approximates searching the most probable point analytically, to reduce the time cost. The results of design examples show that the proposed method provides efficiency curtailing the time for the optimization process and accuracy satisfying the specified reliability.

• 콘크리트학회지
• /
• 제2권2호
• /
• pp.63-72
• /
• 1990

In this study, an optimization design of reinforced concrete structures is performed by using the structural optimization techniques based on the LRFD criteria. The target reliability index is estimated by the optimal reliability index considering the expected cost which is taken as a sum of the structural cost and the expected costs due to failure of the structure. The load and resistance factors calculated by using level I reliability theory with the target reliability index are compared for each load combination (D+L, D+L+w). The results of this study show that the resistance factors are ${\phi}_{M}$=0.90, ${\phi}_{V}$==0.70, ${\phi}_{C}$==0.65 and the load factors are 1.20D + 1.70L, 1.07L + 0.07L + 1.10W. The optimization techinques used to this study are S.L.P. The optimization design based on the LRFD criteria is more economical and rational than other criteria.

• 한국지능정보시스템학회:학술대회논문집
• /
• 한국지능정보시스템학회 2001년도 춘계정기학술대회
• /
• pp.399-408
• /
• 2001

This paper presents a simultaneous optimization approach of case-based reasoning (CBR) using a genetic algorithm(GA) for the prediction of stock price index. Prior research suggested many hybrid models of CBR and the GA for selecting a relevant feature subset or optimizing feature weights. Most studies, however, used the GA for improving only a part of architectural factors for the CBR system. However, the performance of CBR may be enhanced when these factors are simultaneously considered. In this study, the GA simultaneously optimizes multiple factors of the CBR system. Experimental results show that a GA approach to simultaneous optimization of CBR outperforms other conventional approaches for the prediction of stock price index.

• 한국생산제조학회지
• /
• 제19권2호
• /
• pp.224-229
• /
• 2010

This paper presents a reliability-based topology optimization (RBTO) using bi-directional evolutionary structural optimization (BESO). An actual design involves uncertain conditions such as material property, operational load and dimensional variation. Deterministic topology optimization (DTO) is obtained without considering of uncertainties related to the uncertainty parameters. However, the RBTO can consider the uncertainty variables because it has the probabilistic constraints. In this paper, the reliability index approach (RIA) is adopted to evaluate the probabilistic constraint. RBTO based on BESO starting from various design domains produces a similar optimal topology each other. Numerical examples are presented to compare the DTO with the RBTO.

• 한국생산제조학회지
• /
• 제19권6호
• /
• pp.826-833
• /
• 2010

Electric-thermal-structural actuated compliant mechanisms are mechanisms onto which electric voltage drop is applied as input instead of force. This mechanism is based on thermal expansion of material while being heated. Compliant mechanisms are designed subjected to electric charge input using BESO(bi-directional evolutionary structural optimization) method. Reliability-based topology optimization (RBTO) is applied to the topology design of actuators. performance measure approach (PMA), which has probabilistic constraints that are formulated in terms of the reliability index, is adopted to evaluate the probabilistic constraints. In this study, BESO method is used to obtain optimal topology of compliant mechanisms from initial design domain. PMA approach is used to evaluate reliability index. The procedure has been tested in numerical applications and compared with the results obtained by other methods to validate these approaches.

• Structural Engineering and Mechanics
• /
• 제45권2호
• /
• pp.211-232
• /
• 2013

In this study a multi-objective optimization problem is solved. The objectives used here include simultaneous minimum construction cost in term of sections weight, minimum structural damage using a damage index, and minimum non-structural damage in term of inter-story drift under the applied ground motions. A high-speed and low-error neural network is trained and employed in the process of optimization to estimate the results of non-linear time history analysis. This approach can be utilized for all steel or concrete frame structures. In this study, the optimal design of a planar eccentric braced steel frame is performed with great detail, using the presented multi-objective algorithm with a discrete population and then a moment resisting frame is solved as a supplementary example.

• Structural Engineering and Mechanics
• /
• 제88권4호
• /
• pp.369-377
• /
• 2023

In this study, previously developed algorithm is used for Optimization of hybrid composite plates using Tsai-Wu criteria. For the stress-based Design Optimization problems, Von-Mises stress uses as design variable for isotropic materials. Maximum stress, maximum strain, Tsai Hill, and Tsai-Wu criteria are generally used to determine failure of composite materials. In this study, failure index value is used as design variable in the optimization algorithm and Tsai-Wu criteria is utilized to calculate this value. In the analyses, commonly used design domains according to different hybrid orientations are optimized and results are presented. When the optimization algorithm was applied, 50% material reduction was obtained without exceeding allowable failure index value.

• 한국정밀공학회지
• /
• 제32권2호
• /
• pp.179-184
• /
• 2015

In the recent field of Machining, with the improving efficiency of processing, the index table is a key unit according to the increase of parts in available processing when working with the three axes at the same time. As an essential product of MCT, the index tables effect an influence on product quality of machined parts. Therefore, it is necessary to design the shape of index table with stability, high stiffness, lightweight structure. In this study, the optimal shape of index table was proposed using by design of experiment. The maximum displacement and stress analysis were carried out by using FEM software. The optimized shape was verified by using the statistical software. The results of shape optimization were confirmed that both displacement and stress were reduced in comparison with initial model.

• 한국산학기술학회논문지
• /
• 제14권7호
• /
• pp.3528-3537
• /
• 2013

비정형 건축곡면의 패널분할 최적화 정도를 평가하기 위한 여러 가지 최적화 평가기법들이 개발되어 적용되고 있으나 이러한 평가기법과 평가지표들은 독립성, 보편성을 확보하고 있지 못하다. 그러므로 본 연구에서는 비정형곡면 패널분할 최적화 평가기법 및 평가지표에 관한 사례 및 선행연구 고찰을 통한 독립성 및 보편성이 확보되는 비정형 곡면 패널분할 최적화의 정량적 평가를 위한 평가항목 추출과 평가지표의 제안이 이루어진다. 제안된 세 가지 패널분할 최적화 평가항목은 원형 충실도, 생산 용이성, 연속성이며, 원형 충실도를 위한 평가지표로는 곡면 일치, 생산 용이성을 위한 평가지표로는 평면성, 평면 패널 비율, 연속성을 위한 평가지표로는 접선 연속성, 사이 간격이 제안되었으며 그 산출방법이 함께 제안되었다.