• Advances in Computational Design
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• 제7권1호
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• pp.1-17
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• 2022

In this study, a new strategy is presented to transmit the fundamental elastic beam problem into the modern optimization platform and solve it by using artificial intelligence (AI) tools. As a practical example, deflection of Euler-Bernoulli beam is mathematically formulated by 2nd-order ordinary differential equations (ODEs) in accordance to the classical beam theory. This fundamental engineer problem is then transmitted from classic formulation to its artificial-intelligence presentation where the behavior of the beam is simulated by using neural networks (NNs). The supervised training strategy is employed in the developed NNs implemented in the heuristic optimization algorithms as the fitness function. Different evolutionary optimization tools such as genetic algorithm (GA) and particle swarm optimization (PSO) are used to solve this non-linear optimization problem. The step-by-step procedure of the proposed method is presented in the form of a practical flowchart. The results indicate that the proposed method of using AI toolsin solving beam ODEs can efficiently lead to accurate solutions with low computational costs, and should prove useful to solve more complex practical applications.

• Earthquakes and Structures
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• 제1권3호
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• pp.289-306
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• 2010

A gradient-based evolutionary optimization methodology is presented for finding the optimal design of viscous dampers to minimize an objective function defined for a linear multi-storey structure. The maximum value along height of the transfer function amplitudes for the interstorey drifts is taken as the objective function. Since the ground motion includes various uncertainties, the optimal damper placement may be different depending on the ground motion used for design. Furthermore, the transfer function treated as the objective function depends on the properties of structural parameters and added dampers. This implies that a more robust damper design is desired. A reliable and robust damping design system against any unpredictable ground motions can be provided by minimizing the maximum transfer function. Such design system is proposed in this paper.

• 한국생산제조학회지
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• 제20권4호
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• pp.412-418
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• 2011

Reliability-based Topology optimization(RBTO) is to get an optimal design satisfying uncertainties of design variables. Although RBTO based on homogenization and density distribution method has been done, RBTO based on BESO has not been reported yet. This study presents a reliability-based topology optimization(RBTO) using bi-directional evolutionary structural optimization(BESO). Topology optimization is formulated as volume minimization problem with probabilistic displacement constraint. Young's modulus, external load and thickness are considered as uncertain variables. In order to compute reliability index, four methods, i.e., RIA, PMA, SLSV and ADL(adaptive-loop), are used. Reliability-based topology optimization design process is conducted to obtain optimal topology satisfying allowable displacement and target reliability index with the above four methods, and then each result is compared with respect to numerical stability and computing time. The results of this study show that the RBTO based on BESO using the four methods can effectively be applied for topology optimization. And it was confirmed that DLSV and ADL had better numerical efficiency than SLSV. ADL and SLSV had better time cost than DLSV. Consequently, ADL method showed the best time efficiency and good numerical stability.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.818-823
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• 2002

Addition of point supports results in increasing the fundamental frequency of a structure, generally. In this paper, searching more effective location of point supports is a major object to maximize a fundamental frequency of various cantilever plates. Results are presented by aspect ratio of the plate, by design domain within which point supports generate, and by mass location equipped on the plate. Optimization method is applied due to expand the ESO(Evolutionary Structural Optimization) method.

• 한국공작기계학회논문집
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• 제12권4호
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• pp.50-56
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• 2003

Most engineering products contain more than one component. Failure occurs either at the connection itself or in the component at the point of attachment of the connection in many engineering structures. The allocation and design of connections such as bolts, spot-welds, adhesive etc. usually play an important role in the structure of multi-components. Topology optimization of connection component provides more practical solution in design of multi-component connection system. In this study, a topology optimization based on density distribution approach has been applied to optimal location of fasteners such as T-shape, L-shape and multi-component connection system. From the results, it was verified that the number of iteration was reduced, and the optimal topology was obtained very similarly comparing with ESO method. Therefore, it can be concluded that the density distribution method is very suitable for topology optimization of multi-component structures.

• Structural Monitoring and Maintenance
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• 제1권4호
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• pp.427-449
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• 2014

A hybrid optimization method for the identification of state-space models is presented in this study. Hybridization is succeeded by combining the advantages of deterministic and stochastic algorithms in a superior scheme that promises faster convergence rate and reliability in the search for the global optimum. The proposed hybrid algorithm is developed by replacing the original stochastic mutation operator of Evolution Strategies (ES) by the Levenberg-Marquardt (LM) quasi-Newton algorithm. This substitution results in a scheme where the entire population cloud is involved in the search for the global optimum, while single individuals are involved in the local search, undertaken by the LM method. The novel hybrid identification framework is assessed through the Monte Carlo analysis of a simulated system and an experimental case study on a shear frame structure. Comparisons to subspace identification, as well as to conventional, self-adaptive ES provide significant indication of superior performance.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.15-20
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• 2003

Most engineering products contain more than one component. Failure occurs either at the connection itself or in the component at the point of attachment of the connection in many engineering structures. The allocation and design of connections such as bolts, spot-welds, adhesive etc. usually play an important role in the structure of multi-components. Topology optimization of connection component provides more practical solution in design of multi-component connection system. In this study, a topology optimization based on density distribution approach has been applied to optimal location of fasteners such as T-shape, L-shape and multi-component connection system. From the results, it was verified that the number of iteration was reduced, and the optimal topology was obtained very similarly comparing with ESO method. Therefore, it can be concluded that the density distribution method is very suitable for topology optimization of multi-component structures.

• 한국공작기계학회논문집
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• 제16권1호
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• pp.69-74
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• 2007

Topology optimization of the inner reinforcement for a vehicle's hood has been performed by evolutionary structural optimization(ESO) using a smoothing scheme. The purpose of this study is to obtain optimal topology of the inner reinforcement for a vehicle's hood considering the static stiffness of bending and torsion simultaneously. To do this, the multiobjective optimization technique was implemented. Optimal topologies were obtained by the ESO method. From several combinations of weighting factors, a Pareto-optimal solution was obtained. Also, a smoothing scheme was implemented to suppress the checkerboard pattern in the procedure of topology optimization. It is concluded that ESO method with a smoothing scheme is effectively applied to topology optimization of the inner reinforcement of a vehicle's hood considering the static stiffness of bending and torsion.

• 한국구조물진단유지관리공학회 논문집
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• 제18권4호
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• pp.1-9
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• 2014

최근 양자컴퓨터의 개발과 더불어 양자역학의 특성을 응용한 양자기반 탐색기법의 개발과 공학 문제에의 적용은 매우 흥미로운 연구주제 중 하나로 부각되고 있다. 이 알고리즘은 기본적으로 0과 1이 중첩되어진 양자비트를 이용하여 정보가 저장되고, 양자게이트 연산을 통해 해에 접근하게 된다. 이 과정에서 알고리즘은 탐사와 개척 두 가지 탐색 특성간의 균형이 자연스럽게 유지되며, 진화정보가 계속 누적된다는 장점으로 기존의 탐색법과 차별되어 새로운 알고리즘으로 평가되었다. 본 연구에서는 이와 같은 양자기반 진화알고리즘을 평면 트러스의 구조최적화에 적용하여 최소중량설계 기법을 제안하였다. 최적화 수리모형에서 비용함수는 최소중량이며, 제약함수는 변위와 응력에 관한 함수로 구성하였다. 진화정보의 누적과 수렴 과정을 알아보기 위해서 10부재 평면 트러스와 17부재 평면트러스 예제를 수치예제로 채택하여 결과를 분석하였다. 수치예제의 구조최적설계 결과에서 볼 때, 기존의 고전적 탐색기법의 연구결과와 비교해서 더 나은 최소중량 설계의 결과를 얻을 수 있었으며, 진화정보의 누적된 결과로 해의 정밀도를 관찰할 수 있었다. 또한 누적된 진화정보인 양자비트의 확률적 표현은 종료시점을 쉽게 판단할 수 있다.

• 한국지진공학회논문집
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• 제15권2호
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• pp.1-9
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• 2011

불확실성을 가지는 하중의 변동성을 고려한 구조제어시스템의 최적설계방법에 관하여 연구하였다. 일반적인 제어시스템의 설계 문제가 구조물과 제어시스템간의 상호작용 고려하여 구조-제어 시스템을 최적화이나, 이 연구에서는 하중-구조물-제어 시스템간의 상호작용에 대한 최적설계방법에 관하여 다루었다. 구조물의 응답을 최대화하는 하중과, 이를 최소화하는 구조제어시스템을 동시에 구하는 최대-최소문제(Min-max Problem)를 정식화하고, 최적설계변수를 효율적으로 찾는 방법으로 병렬진화 알고리즘을 이용하여 불확실성이 존재하는 선형구조제어시스템의 최적설계방법을 제시하였다. 지진하중을 받는 구조물의 제진시스템 설계 예 및 수치해석을 통하여 연구한 방법의 타당성을 검증하였다.