• 전산구조공학
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• 제5권1호
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• pp.133-142
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• 1992

본 논문은 수식화의 특이성 때문에 구조 최적화 문제에 거의 사용되지 않고 있는 선형 goal programming을 대규모 비선형 구조 최적화에 응용하는 방법을 제시한다. 이 방법은 다기준 최적화의 도구로 사용되는데 그 까닭은 goal programming이 목적함수와 제한조건등을 정의하는데 있어서 발생하는 난점들을 제거해 주기 때문이다. 이 방법은 비선형 goal 최적화 문제들의 해를 얻기 위해서 유한요소해석, 선형 goal programming기법, 그리고 계속적인 선형화 기법을 이용한다. 즉, 대규모 비선형 구조 최적화 문제를 비선형 goal programming형태로 전환시키는 일반적인 수식화 방법을 제시하고, 얻어진 비선형 goal 최적화 문제를 풀기 위한 계속적인 선형화 방법에 대해서도 논의한다. 설계도구로서 이 방법의 유효성을 논증하기 위하여 10, 25 및 200트러스의 사례를 가지고 응력제한조건들의 최소무게 구조 최적화 문제에 대한 해를 모색하며 이를 다른 연구결과와 비교검토한다.

• Structural Engineering and Mechanics
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• 제15권6호
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• pp.669-683
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• 2003

The stochastic optimal nonlinear control of coupled adjacent building structures is studied based on the stochastic dynamical programming principle and the stochastic averaging method. The coupled structures with control devices under random seismic excitation are first condensed to form a reduced-order structural model for the control analysis. The stochastic averaging method is applied to the reduced model to yield stochastic differential equations for structural modal energies as controlled diffusion processes. Then a dynamical programming equation for the energy processes is established based on the stochastic dynamical programming principle, and solved to determine the optimal nonlinear control law. The seismic response mitigation of the coupled structures is achieved through the structural energy control and the dimension of the optimal control problem is reduced. The seismic excitation spectrum is taken into account according to the stochastic dynamical programming principle. Finally, the nonlinear controlled structural response is predicted by using the stochastic averaging method and compared with the uncontrolled structural response to evaluate the control efficacy. Numerical results are given to demonstrate the response mitigation capabilities of the proposed stochastic optimal control method for coupled adjacent building structures.

• 국제학술발표논문집
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• The 8th International Conference on Construction Engineering and Project Management
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• pp.225-234
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• 2020

Reliability-based structural optimization usually requires designers or engineers model different designs manually, which is considered very time consuming and all possibilities cannot be fully explored. Otherwise, a lot of time are needed for designers or engineers to learn mathematical modeling and programming skills. Therefore, a framework that integrates generative design, structural simulation and reliability theory is proposed. With the proposed framework, various designs are generated based on a set of rules and parameters defined based on visual programming, and their structural performance are simulated by OpenSees. Then, reliability of each design is evaluated based on the simulation results, and an optimal design can be found. The proposed framework and prototype are tested in the optimization of a steel frame structure, and results illustrate that generative design based on visual programming is user friendly and different design possibilities can be explored in an efficient way. It is also reported that structural reliability can be assessed in an automatic way by integrating Dynamo and OpenSees. This research contributes to the body of knowledge by providing a novel framework for automatic reliability evaluation and structural optimization.

• Structural Engineering and Mechanics
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• 제26권1호
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• pp.15-30
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• 2007

In the paper, one focuses on the problem of duality in non-linear programming, applied to the solution of no-tension problems by means of Limit Analysis (LA) theorems for Not Resisting Tension (NRT) models. In details, one demonstrates that, starting from the application of the duality theory to the non-linear program defined by the static theorem approach for a discrete NRT model, this procedure results in the definition of a dual problem that has a significant physical meaning: the formulation of the kinematic theorem.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1992년도 가을 학술발표회 논문집
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• pp.105-111
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• 1992

A computer program for matrix structural analysis by object-oriented programming technique using $C^{++}$ language has been developed. Object, class, method and inheritance which are used in object-oriented programming are illustrated using a graphical representation. The matrix operations and the structural analysis by matrix displacement method were satisfactorily performed by the proposed program. Numerical tests demonstrate that this proposed program can be widely used for the matrix structural analysis for personal computers.s.

• 전산구조공학
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• 제5권4호
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• pp.125-132
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• 1992

본 연구에서는 C++언어를 이용한 객체지향 프로그래밍 기법으로 매트릭스 연산과 평면뼈대 구조물의 해석이 가능한 PC용 구조해석 프로그램을 개발하였다. 객체지향 프로그래밍에서의 주요 개념인 객체, 클래스, 처리방식, 상속성 및 다형성을 도식화하여 설명하였으며, 매트릭스 연산과 평면뼈대 구조해석에 대한 예제 해석 결과는 이 프로그램의 효율성과 타당성을 보여 주었다. 따라서 본 연구는 객체지향 프로그래밍기법의 특징인 프로그램의 확장성과 재사용성 및 다양한 GUI의 구현가능성을 이용하여 앞으로의 객체지향 유한요소 프로그램 개발에 활용될 것이다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1993년도 봄 학술발표회논문집
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• pp.135-140
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• 1993

The optimum weight design of structure is to determine the combination of structural members which minimize the weight of structures and satisfy design conditions as well. Since most of loads and design variables considered in structural design have uncertain natures, the reliability-based optimization techniques need to be developed. The aim of this study is to estabilish the general algorithm for the minimum weight design of transmission tower structure system with reliability constraints. The sequential linear programming method is used to solve non-linear minimization problems, which converts original non-linear programming problems to sequential linear programming problems. The optimal solutions are produced for various reliability levels such as reliability levels inherent in current standard transmission tower cross-section and optimal transmission tower cross-section obtained with constraints of current design criteria as well as selected target reliability index. The optimal transmission towers satisfying reliability constraints sustain consistent reliability levels on all members. Consequently, more balanced optimum designs are accomplished with less structural weight than traditional designs dealing with deterministic design criteria.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.497-504
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• 2003

An optimal design method for hybrid structural control system of building structures subject to earthquake excitation is presented in this paper. Designing a hybrid structural control system nay be defined as a process that optimizes the capacities and configuration of passive and active control systems as well as structural members. The optimal design proceeds by formulating the optimization problem via a multi-stage goal programming technique and, then, by finding reasonable solution to the optimization problem by means of a goal-updating genetic algorithm. The process of the integrated optimization design is illustrated by a numerical simulation of a nine-story building structure subject to earthquake excitation. The effectiveness of the proposed method is demonstrated by comparing the optimally designed results with those of a hybrid structural control system where structural members, passive and active control systems are uniformly distributed.

• Smart Structures and Systems
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• 제5권1호
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• pp.69-79
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• 2009

A non-clipped semi-active stochastic optimal control strategy for nonlinear structural systems with MR dampers is developed based on the stochastic averaging method and stochastic dynamical programming principle. A nonlinear stochastic control structure is first modeled as a semi-actively controlled, stochastically excited and dissipated Hamiltonian system. The control force of an MR damper is separated into passive and semi-active parts. The passive control force components, coupled in structural mode space, are incorporated in the drift coefficients by directly using the stochastic averaging method. Then the stochastic dynamical programming principle is applied to establish a dynamical programming equation, from which the semi-active optimal control law is determined and implementable by MR dampers without clipping in terms of the Bingham model. Under the condition on the control performance function given in section 3, the expressions of nonlinear and linear non-clipped semi-active optimal control force components are obtained as well as the non-clipped semi-active LQG control force, and thus the value function and semi-active nonlinear optimal control force are actually existent according to the developed strategy. An example of the controlled stochastic hysteretic column is given to illustrate the application and effectiveness of the developed semi-active optimal control strategy.

• Structural Engineering and Mechanics
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• 제7권5호
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• pp.485-502
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• 1999

Using the continuous Hopfield network model as the basis to solve the general crisp and fuzzy constrained optimization problem is presented and examined. The model lies in its transformation to a parallel algorithm which distributes the work of numerical optimization to several simultaneously computing processors. The method is applied to different structural engineering design problems that demonstrate this usefulness, satisfaction or potential. The computing algorithm has been given and discussed for a designer who can program it without difficulty.