• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.3
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• pp.259-265
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• 2009

This paper studies the Element Connectivity Parameterization Method(ECP method) for topology optimization considering dynamic compliance. The previous element density based topology optimization method interpolates Young's modulus with respect to design variables defined in each element for topology optimization. Despite its various applications, these element density based methods suffer from numerical instabilities for nonlinear structure and multiphysics systems. To resolve these instabilities, recently a new numerical method called the Element Connectivity Parameterization(ECP) Method was proposed. Unlike the existing design methods, the ECP method optimizes the connectivities among plane or solid elements and it shows some advantages in topology optimization for both nonlinear structure and multiphysics systems. In this study, the method was expanded for topology optimization for the dynamic compliance by developing a way to model the mass matrix in the framework of the ECP method.

• Computational Structural Engineering
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• v.9 no.3
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• pp.169-177
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• 1996

The focus of this study is on the problem of the design of structure of undetermined topology. This problem has been regarded as being the most challenging of structural optimization problems, because of the difficulty of allowing topology to change. Conventional approaches break down when element sizes approach to zero, due to stiffness matrix singularity. In this study, a novel nonlinear programming formulation of the topology problem is presented. Its main feature is the ability to account for topology variation through zero element sizes. Stiffness matrix singularity is avoided by embedding the equilibrium equations as equality constraints in the optimization problem. Although the formulation is general, two dimensional plane elasticity examples are presented. The design problem is to find minimum weight of a plane structure of fixed geometry but variable topology, subject to constraints on stress and displacement. Variables are thicknesses of finite elements, and are permitted to assume zero sizes. The examples demonstrate that the formulation is effective for finding at least a locally minimal weight.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.3
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• pp.339-348
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• 2001

More often a commercial package for the structural analysis is necessary in the structural optimum design. In this case the task of combining the package with an optimization program must be required, hut it is not so simple because interchanging some data between them is difficult. Sequential approximate optimization is currently used as a natural way to overcome the hard task. If sequential approximate optimization has wide side constraints that the lower limit of design variables is very small and their upper limit is very large, it is not so easy to obtain approximated functions accurately for the whole design domain. This paper proposes a sequential design domain method, which is very useful to carry out sequential approximate optimization in this case. In this paper, the response surface methodology is used to obtain approximated functions and the orthogonal array is used for design of experiments. The sequential approximate optimization of 3-bar and 10-bar trusses is demonstrated to verify the reliability of the sequential design domain method.

• Composites Research
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• v.21 no.1
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• pp.30-39
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• 2008

In this paper, a parallel micro genetic algorithm was utilized in the optimal design of composite structures instead of a conventional genetic algorithm(SGA). Micro genetic algorithm searches the optimal design variables with only 5 individuals. The diversities from the nominal convergence and the re-initialization processes make micro genetic algorithm to find out the optimums with such a small population size. Two different composite structure optimization problems were proposed to confirm the efficiency of micro genetic algorithm compared with SGA. The results showed that micro genetic algorithm can get the solutions of the same level of SGA while reducing the calculation costs up to 70% of SGA. The composite laminated structure optimization under the load uncertainty was conducted using micro genetic algorithm. The result revealed that the design variables regarding the load uncertainty are less sensitive to load variation than that of fixed applied load. From the above-mentioned results, we confirmed micro genetic algorithm as a optimization method of composite structures is efficient.

• The Transactions of the Korea Information Processing Society
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• v.7 no.1
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• pp.12-19
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• 2000

In the development of a production process scheduling system a collaboration method must be defined for the cooperation among submodules within the system. The blackboard architecture is exploited for solving the collaboration problem, which is one of the problem solving architecture that belongs to the distributed artificial intelligence. The dynamic states of the problem solving processes are presented in the hierarchically constructed shared working memory called as a blackboard. The communication for the collaboration is done through the blackboard. The problem solving steps are contained in the global controller, one of a component that consists the blackboard architecture, as knowledge. The global controller activates proper submodules based on the knowledge. By applying the blackboard architecture the collaboration problem among submodules in the grating production process scheduling system (GPSS) has been solved as well as the system became adaptable to the future modifications and expansions.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.4
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• pp.221-230
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• 2021

This paper proposes full waveform inversion (FWI) for estimating the physical properties of a layered half-space. An FWI solution is obtained using a genetic algorithm (GA), which is a well-known global optimization approach. The dynamic responses of a layered half-space subjected to a harmonic vertical disk load are measured and compared with those calculated using the estimated physical properties. The responses are calculated using the thin-layer method, which is accurate and efficient for layered media. Subsequently, a numerical model is constructed for a layered half-space using mid-point integrated finite elements and perfectly matched discrete layers. An objective function of the global optimization problem is defined as the L2-norm of the difference between the observed and estimated responses. A GA is used to minimize the objective function and obtain a solution for the FWI. The accuracy of the proposed approach is applied to various problems involving layered half-spaces. The results verify that the proposed FWI based on a GA is suitable for estimating the material properties of a layered half-space, even when the measured responses include measurement noise.

• Proceedings of the Korea Association of Information Systems Conference
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• 1997.10a
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• pp.83-88
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• 1997

시스템 성능을 개선하고 변화하는 환경에 적응하기 위해서는 기존 시스템을 실험, 분석함으로써 정확한 이해를 획득하고 나아가 재사용 자원으로 활용할 수 있는 소프트웨어 역공학이 필요하다. 또한 설계 문제의 추상화와 특정 영역의 일반적인 해결책에 대한 정보 표현 및 그 관계는 패턴 형식을 통해 효과적으로 나타낼 수 있다. 즉, 시스템의 설계 구조 를 추출하여 시스템 분석과 설계를 향상시키고 표준화 된 설계 용어 및 컴퍼넌트 관계 구조 를 통해 재사용을 용이하게 하는 설계 패턴 추출을 위한 역공학은 중요하다. 따라서 본 논 문에서는 기존 코드에서 설계 패턴 추출을 위한 역공학 적용의 타당성과 설계 패턴 자동 추 출을 위한 몇 개의 알고리즘을 살펴보고 간단히 적용시켜 본다.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2000.11a
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• pp.82-87
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• 2000

최근 들어 산업설비 및 건축물의 대형화, 다 기능화 추세가 두드러지게 나타나고 있는 가운데 외부침입에 의한 재산상의 피해 및 기밀누설 등의 문제가 급증하고있는 추세이다. 이에 외부침입에 대한 근원적인 원인과 발생가능성을 미연에 방지하는 보안시스템의 개발이 무엇보다도 중요해지고 있다. 기존의 보안시스템은 인간이 직접 경계활동을 벌이는 구조 또는 장력, 광케이블을 이용한 보안망의 구조를 가지고 있다. 이들 시스템은 보안효과의 비능률성, 고가, 기계적강도의 떨어짐 등의 문제를 지니고 있다 이에 본 연구는 울타리로써의 역할만을 강조하는 기존의 펜스의 기능에 자기 판단능력을 부여함으로서 한 단계 진보된 성능의 보안시스템 개발에 그 목적을 두고 있다(중략)

• Computational Structural Engineering
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• v.3 no.3
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• pp.58-61
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• 1990

교량유지관리 업무는 교량의 건설(신설), 노후교량의 개축, 교통량 증가에 따른 교량의 확장, 보수를 통한 원상복구, 또한 보수기록의 보관문제, 기존교량의 계속적인 점검 및 조사 등으로 분류된다. 이러한 문제를 전산화 하는 것은 필요항목들을 특성별로 분류하여 각 항목 등에 대한 데이타베이스를 구축하고 교량의 점검 및 조사 등을 통하여 교량의 손상상태를 파악함은 물론 개축, 보수, 확장, 신설 등에 대한 판정 및 그 우선순위를 제시하여 주는 의사결정시스템 개발이다. 본 고에서는 교량관리업무를 전산화하기 위해 한국건설기술연구원에서 개발한 교량관리용 DB(DATA BASE)시스템에 대하여 간략히 소개하고자 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.100-102
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• 2004

예측할 수 없이 빈번하게 발생하는 인터럽트와 인터럽트 처리시간의 대부분을 차지하는 하반부 처리시간에 의해서 스케줄러는 사용자 프로세스에게 정상적으로 CPU를 할당해 줄 수 없는 이른바 “ 빼앗긴 시간 문제” 가 발생하게 된다. 본 논문에서는 이러한 문제를 해결하기 위해서, 하반부들이 사용할 수 있는 최대시간을 동적으로 계산하고, 처리시간을 제한하는 “하반부 스케줄링” 방범을 제안하고, 제안한 구조를 리눅스에서 구현하고 제안된 구조에 의해서 사용자 프로세스에게 할당된 CPU 시간을 안정화시킬 수 있음을 멀티미디어 응용을 사용한 실험을 통해서 보이고자 한다.