• Structural Engineering and Mechanics
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• 제86권2호
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• pp.249-260
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• 2023

The uncertainties involved in structural performances are of importance when the optimum number and property of seismic retrofit devices are determined. This paper proposes a seismic retrofit design framework for asymmetric soft-first-story buildings, considering uncertainties in the soil condition and seismic retrofit device. The effect of the uncertain parameters on the structural performance is used to find a robust and optimal seismic retrofit solution. The framework finds a robust and optimal seismic retrofit solution by finding the optimal locations and mechanical properties of the seismic retrofit device for different realizations of the uncertain parameters. The structural performance for each realization is computed to evaluate the effect of the uncertainty parameters on the seismic performance. The framework utilizes parallel processing to decrease the computationally intensive nonlinear dynamic analysis time. The framework returns a robust design solution that satisfies the given limit state for every realization of the uncertain parameters. The proposed framework is applied to the seismic retrofit design of a five-story asymmetric soft-first-story case study structure retrofitted with a viscoelastic damper. Robust optimal parameters for retrofitting a structure to satisfy the limit state for the different realizations of the uncertain parameter are found using the proposed framework. According to the performance evaluation results of the retrofitted structure, the developed framework is proved effective in the seismic retrofit of the asymmetric structure with inherent uncertainties.

• 한국구조물진단유지관리공학회 논문집
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• 제19권2호
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• pp.22-32
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• 2015

본 연구는 MIDAS-Gen을 사용하여 초고층건물에서 단일 아웃리거 구조의 최적위치에 미치는 구조요소의 영향에 대하여 비교분석하고자 하였다. 본 연구에서는 구조해석의 변수로 아웃리거 위치와 전단벽, 아웃리거, 아웃리거와 연결된 외곽기둥, 아웃리거에 연결되지 않은 프레임과 같은 주요한 구조요소의 강성을 설정하였다. 초고층건물에서 단일 아웃리거 구조의 최적위치를 탐색하기 위하여 80층 건물의 최상층에 발생한 수평변위를 고찰하였다. 본 연구 결과로부터 아웃리거의 위치, 전단벽, 아웃리거, 아웃리거와 연결된 외곽기둥, 아웃리거와 연결되지 않은 프레임과 같은 주요한 구조요소의 강성은 단일의 아웃리거 최적 위치에 영향을 주는 것으로 나타났다. 그리고 본 연구 결과는 초고층건물에서 단일의 아웃리거 최적위치를 탐색하기 위한 구조설계 데이터를 취득하는 데 매우 유용할 것으로 기대된다.

• 한국정밀공학회지
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• 제14권2호
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• pp.66-73
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• 1997

In many optimal methods for the structural design, the structural analysis is performed with the given design parameters. Then the design sensitivity is calculated based on its structural anaysis results. There-after, the design parameters are changed iteratively. But genetic algorithm is a optimal searching technique which is not depend on design sensitivity. This method uses for many design para- meter groups which are generated by a designer. The generated design parameter groups are become initial population, and then the fitness of the all design parameters are calculated. According to the fitness of each parameter, the design parameters are optimized through the calculation of reproduction process, degradation and interchange, and mutation. Those are the basic operation of the genetic algorithm. The changing process of population is called a generation. The basic calculation process of genetic algorithm is repeatly accepted to every generation. Then the fitness value of the element of a generation becomes maximum. Therefore, the design parameters converge to the optimal. In this study, the optimal design pro- cess of a machine tool structure for static loading is presented to determine the optimal base supporting points and structure thickness using a genetic algorithm.

• Steel and Composite Structures
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• 제3권4호
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• pp.277-287
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• 2003

The low boundary of load carrying capacity of the elastic-plastic spatial grid structures depend on numerous values and their variability assumed in designing process. Analysed influence all this values in searching for optimal variant of the structure lead to too great problem even taking into consideration actual computational power we have in disposal. Therefore one can take only a few values which have greatest influence on the optimal choice. In optimal analysis of the elastic-plastic spatial grid structures the previously proposed method with subsequent modification (Karczewski 1980), (Karczewski, Barszcz and Donten 1996), (Karczewski and Donten 2001) as well as computer program which was worked out by Donten K. to make possible practical utilisation this method was employed. The paper deal with evaluation of influence dimensions of particular values for choice of optimal variant of the structure. One among this values is distribution of the struts in the structure.

• 한국농공학회지
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• 제27권4호
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• pp.61-67
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• 1985

This study is concerned with the optimum design of reinforced concrete frame structure with multi-stories and multi-bays by Limit State Design Method aimed to establish a synthetical optimal method that can simultaneously acomplish structural analysis and sectional desig. For optimum solution, the Successive Linear Programming known as effective to nonlinear optimization problem: including both multi-design variables and mulit-constrained condition was applied. The developed algorithm was applied to an actual structure and reached following results. 1)The developed algorithm was rvey effective converging to an optimal solution with 3 to 5 iteration. 2)An optimal solution was showed when bending moment redistribution factor a was 0.80. 3)The column was, regardless of story, controlled by the long column when unbraced, while in case of braced column, it is designed with 3 short column controlled by thrust and bending moment, and the supporting condition had little effect on the optimization results.

• 전자공학회논문지B
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• 제32B권12호
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• pp.1670-1679
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• 1995

In this paper, an optimal variable structure controller with a multilayer neural inverse identifier is proposed. A multilayer neural network with error back propagation learning algorithm is used for construction the neural inverse identifier which is an observer of the external disturbances and the parameter variations of the system. The variable structure controller with the multilayer neural inverse identifier not only needs a small part of a priori knowledge of the bounds of external disturbances and parameter variations but also alleviates the chattering magnitude of the control input. Also, an optimal sliding line is designed by the optimal linear regulator technique and an integrator is introduced for solving the reaching phase problem. Computer simulation results show that the proposed approach gives the effective control results by reducing the chattering magnitude of control input.

• 노동경제논집
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• 제23권2호
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• pp.39-59
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• 2000

본 논문에서는 현실적으로 실업보험급여가 수급기간별로 차등지급되기 어렵다는 전제하에 가장 바람직한 실업급여체계가 어떠한 것인가를 분석하고 있다. 특히 법정수급기간과 소득대체율이 실업자들의 구직유인과 소득안정에 대해 미치는 영향을 파악하고, 이에 따라 사회후생을 극대화시킬 수 있는 법정 수급기간 및 소득대체율의 조합을 분석하고 있다. 아울러 본 모형을 통해 적정 실업급여체계를 결정하는 여러 가지 요인들을 도출하고, 그에 의거하여 앞으로 우리나라의 고용보험제도의 개혁 방향을 제시하고 있다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.936-941
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• 2004

An Optimal Feedforward Integral Variable Structure or FIVSC approach for an electrohydraulic position servo control system is presented in this paper. The FIVSC algorithm combines feedforward strategy and integral in the conventional Variable Structure Control (VSC) and calculating the control function to guarantee the existence of a sliding mode. Furthermore, the chattering in the control signal is suppressed by replacing the sign function in the control function with a smoothing function. The simulation results illustrate that the purposed approach gives a significant improvement on the tracking performances when compared with some existing control methods, like the IVSC and MIVSC strategies. Simulation results illustrate that the purposed approach can achieve a zero steady state error for ramp input and has an optimal motion with respect to a quadratic performance index. Moreover, Its can achieve accurate servo tracking in the presence of plant parameter variation and external load disturbances.

• Journal of electromagnetic engineering and science
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• 제3권1호
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• pp.17-21
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• 2003

In this paper, we design an optimal planar array geometry for maximum side-lobe reduction. The concept of thinned array is applied to obtain an optimal two dimensional(2-D) planar array structure. First, a 2-D rectangular array with uniform spacing is used as an initial planar array structure. Next, we modify the initial planar array geometry with the aid of thinned array theory in order to reduce the maximum side-lobe level. This is implemented by a genetic algorithm under some constraint, minimizing the maximum side-lobe level of the 2-D planar array. It is shown that the optimized planar array structure can achieve low side-lobe level without optimizing the excitations of the array antennas.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1999년도 봄 학술발표회 논문집
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• pp.287-294
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• 1999

The tensegrity structure by prestressed cable, which may have large freedom in scale and form and therefore are received much attention from the view points of their light weight and aesthetics, is a very flexible and geometrically unstable structure because the cable material has little initial rigidity. For the stable self-equilibrated state of the usually very deformable structure, the method to find the optimal initial stress by the shape analysis is proposed in this paper. The proposed procedure is to derive the nonlinear finite element formula of cable and truss members considering geometric nonlinearity and used to modified load incremental method adding to Newton-Raphson method with the proposed condition for optimal initial stress. The result of the shape analysis for the tensegrity structure with the radius of 30m is shown the almost approximated shape to architectural shape and the changed procedure of initial stress