• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.731-734
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• 1997

In this study, a shape optimization is performed for circular and elliptical holes to reduce weight of a plate. It is accomplished in reference to the results of topology optimization of the square plate with circular hole. From the results. it is concluded that the stress values of shape optimization of them are satisfied with 100MPa of constraint condition.

• Journal of the Korean Statistical Society
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• 제22권1호
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• pp.1-12
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• 1993

An approach to make the information bound sharper in median-unbiased estimation, based on an analogue of the Cramer-Rao inequality developed by Sung et al. (1990), is introduced for continuous densities with a nuisance parameter by considering information quantities contained both in the parametric function of interest and in the nuisance parameter in a linear fashion. This approach is comparable to that of improving the information bound in mean-unbiased estimation for the case of two unknown parameters. Computation of an optimal weight corresponding to the nuisance parameter is also considered.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 봄 학술발표회 논문집
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• pp.173-180
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• 2001

In this study steel box girders used as main members of a two span continuous steel bridge, are optimally designed by a Load and Resistance Factor Design method(LRFD) using an numerical optimization method. The width, height, web thickness and flange thickness of the main girder are set as design variables, and light weight design is attempted by choosing the cross-sectional area as an object function. We studied the results of steel box girders and compared with those of 1-type girders. The main program is coded with C++ and connected with optimization modul ADS. which is coded with FORTRAN.

• 한국강구조학회 논문집
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• 제17권1호통권74호
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• pp.13-21
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• 2005

본 논문에서는 강아치교의 고등해석과 최적설계를 수행하였다. 고등해석은 해석시에 구조계와 그에 속한 부재의 강도와 안정을 직접 고려함으로서, 해석후 개별부재의 강도검토가 필요없는 설계방법을 지칭한다. 기하학적 비선형 효과를 고려하기 위하여 안정함수를 사용하였다. 잔류응력으로 인한 점진적인 소성화를 고려하기 위하여 CRC 접선 탄성계수를 사용하였다. 탄성강성에서 완전소성강성까지 점진적인 소성화를 나타내기 위하여 포물선 함수를 사용하였다. 최적화 기법으로는 수정된 단면점증법을 사용하였다. 수정된 단면점증법은 AASHTO-LRFD의 상관방정식으로 계산된 값중에서 최대값을 가지는 부재의 크기를 단계별로 증가시키는 방법이다. 목적함수는 구조물의 중량을 사용하였으며, 제약조건식은 구조시스템의 하중-저항능력 및 처짐 조건을 고려하였다. 제안된 방법에 의한 설계결과를 기존의 연구결과와 비교하였다.

• 대한전자공학회논문지TC
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• 제41권8호
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• pp.1-7
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• 2004

주파수 비선택적 Rayleigh 페이딩 채널에서 준 최적 빔 형성과 페이딩 상관이 폐루프 송신 안테나 다이버시티(CTD) 시스템에 주는 영향을 분석하였다. 이동국에서 채널을 완벽하게 예측하는 것은 빠르게 변하는 채널의 페이딩으로 매우 어렵기 때문에 각각의 송신 안테나에 불완전한 가중치를 곱하게 된다. 이 불완전한 가중치는 준 최적의 빔을 형성하게 되고, CTD 시스템의 성능을 저하시킨다. 무선 채널의 페이딩 상관 역시 다이버시티 이득을 감소시키는 하나의 요소이다. CTD 시스템의 비트오율을 채널 예측 에러, 채널 상관계수, 궤환지연, 그리고 페이딩 지수의 함수로 해석적으로 유도하였다. 해석 결과 채널 예측에러가 채널상관보다 시스템성능에 더 많은 영향을 주는 것을 알 수 있었다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.321-324
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• 2006

LMTT(Linear Motor based Transfer Technology) is a new type of transfer system used in the maritime container terminal for the port automation, and largely consists of a controller, shuttle car, and rail. The shuttle car is divided into the frame part, the driving part, and wheels. In order to design this system, various researches on each part of it must be conducted. In this study, we dealt with the optimum design for the mover of the shuttle car designed from previous studies on the strength of the frame with respect to the number of cross beams to minimize the weight of the shuttle car and to satisfy design criteria of cargo-handling systems in container terminal. For the optimization of the mover, thicknesses of each beam were adopted as design variables, the weight of the frame as objective function, and stress and deflection per unit length as constraint condition.

• 한국전산구조공학회논문집
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• 제16권1호
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• pp.105-111
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• 2003

승용차의 휠은 타이어와 차체 무게를 지지하며, 회전력과 정지력을 노면으로 전달한다. 휠의 경량화는 차량의 연료효율에 효과적이므로, 스틸휠이 무게를 최소화하도록 디스크 홀이 형상을 최적화 하였다. 설계모델은 Pro/ENGINEER를 사용하여 설정하고, 설계모델의 해석은 ANSYS를 이용하였다. 범용 소프트웨어간의 직접적인 자료의 전달이 어려우므로 두 프로그램을 병합 사용하기 위해, 반응표면법을 이용한 근사함수를 구하였다. 5수준의 요인배치법의 실험값을 사용하여 최대응력과 최대 변위를 추출하였다. 초기 모델은 14인치 승용차용 스틸휠을 사용하였고, 디스크 홀의 폭을 설계변수로 선택하였다. 순차이차계획법과 활성화제약조건을 사용하는 PLBA(Pahenichny-Lim-Belegundu-Arora) 알고르즘을 이용하여 최적해를 구하였다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.366-371
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• 2002

Because of the environmental problems, automotive companies are trying to reduce the weight of car body. Therefore, TRIP(TRansformation Induced Plasticity) steels, which have high strength and ductility have been developed. Welding process is a complex process; therefore deciding the optimal welding conditions on the basis of experimental data is an effective method. However, trial-and-error method to decide the optimal conditions requires too many experiments. To overcome these problems, response surface methodology was used. Response surface methodology is a collection of mathematical and statistical techniques that are used in the modeling and analysis of problems in which a response of interest is influenced by several variables and the objective is to optimize this response. This method was applied to the resistance spot welding process of the TRIP steel to optimize the welding parameters.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표대회 논문집(III)
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• pp.712-717
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• 1998

Represtressed preflex beams do not allow tensile stress under service load by introducing additional prestressing at the lower concrete of beams. In this study, optimal design of represetressed preflex beams are numerically investigated. Design variables are dimension of plate girder. Object function is the total weight of plate girder. Constraints of the stress of plate girder and upper and lower concrete flange and lower and upper bounds on the design variables are imposed. Structural analysis is performed by D.A.R.P.(Design and Analysis of Represtressed Preflex beams). For numerical optimization, ADS(Garret N. Vanderplaats) program is used. From result of application examples, optimum designs of different cases are successfully obtained. The design program developed in this study seems efficient and robust for the optimization of represtressed preflex beams.

• Structural Engineering and Mechanics
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• 제51권5호
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• pp.707-725
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• 2014

In order to improve the crane-hook's performance and service life, we formulate a multi-criteria shape design problem considering practical conditions. The structural weight, the displacement at specified points and the induced matrix norm of stiffness matrix are adopted as the evaluation items to be minimized. The heights and widths of cross-section are chosen as the design variables. The design variables are expressed in terms of shape functions based on the Gaussian function. For this multi-objective optimization problem with three items, we utilize a multi-objective evolutionary algorithm, that is, the multi-objective Particle Swarm Optimization (MOPSO). As a common feature of obtained solutions, the side views are tapered shapes similar to those of actual crane-hook designs. The evaluation item values of the obtained designs demonstrate importance of the present optimization as well as the feasibility of the proposed optimal design approach.