• 한국안전학회지
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• 제26권4호
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• pp.80-86
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• 2011

Structural optimization algorithm of steel box girder bridges using improved higher-order approximate reanalysis technique is proposed in this paper. The proposed approximation method is a generalization of the convex approximation method. The order of the approximate reanalysis for each function is analytically adjusted in the optimization process. This self-adjusted capability makes the approximate structural analysis values conservative enough to maintain the optimum design point of the approximate problem. The efficiency of proposed optimazation algorithm, compared with conventional algorithm, is successfully demonstrated in the steel box girder bridges. The efficiency and robustness of proposed algorithm is also demonstrated in practical steel box girder bridges.

• Journal of information and communication convergence engineering
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• 제9권4호
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• pp.471-474
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• 2011

In parallel job scheduling, each job can be executed simultaneously on multiple machines at a time. Thus in the input instance, a job $J_i$ requires the number $m_i$ of machines on which it shall be processed. The algorithm should determine not only the execution order of jobs but also the machines on which the jobs are executed. In this paper, when the jobs have deadlines, the problem is to maximize the total work of jobs which is completed by their deadlines. The problem is known to be strongly NP-hard [5] and we investigate the approximation algorithms for the problem. We consider a model in which the algorithm can have more machines than the adversary. With this advantage, the problem is how good solution the algorithm can produce against the optimal algorithm.

• 대한기계학회논문집A
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• 제35권3호
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• pp.259-266
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• 2011

본 논문에서는 SD-TDQAO (Sequential Dual - Two-point Diagonal Quadratic Approximate Optimization)라는 쌍대기법을 이용한 순차적 최적설계 알고리즘을 제안한다. 이 방법은 비선형 목적함수와 제한조건이 포함되어 있는 공학적인 문제를 효과적으로 풀 수 있도록 하는데 목적이 있다. 기존의 볼록성과 분리성이 만족되지 않는 eTDQA2 방법을 이용하여 쌍대기법에 이용할 수 있도록 이차 근사함수의 헤시언 대각요소에 이를 적용하여 쉽게 볼록성과 분리성을 보장할 수 있도록 하였다. 또한 이를 수학적 예제와 위상 최적설계문제를 통해 기존의 쌍대기법 알고리즘인 MMA 와의 비교로 그 성능을 입증하였다.

• Structural Engineering and Mechanics
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• 제76권6호
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• pp.799-821
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• 2020

The optimum design of truss structures is one of the significant categories in structural optimization that has widely been applied by researchers. In the present study, new mathematical programming called Consistent Approximation (CONAP) method is utilized for the simultaneous optimization of the size and shape of truss structures. The CONAP algorithm has already been introduced to optimize some structures and functions. In the CONAP algorithm, some important parameters are designed by employing design sensitivities to enhance the capability of the method and its consistency in various optimum design problems, especially structural optimization. The cross-sectional area of the bar elements and the nodal coordinates of the truss are assumed to be the size and shape design variables, respectively. The displacement, allowable stress and the Euler buckling stress are taken as the design constraints for the problem. In the proposed method, the primary optimization problem is replaced with a sequence of explicit sub-problems. Each sub-problem is efficiently solved using the sequential quadratic programming (SQP) algorithm. Several truss structures are designed by employing the CONAP method to illustrate the efficiency of the algorithm for simultaneous shape and size optimization. The optimal solutions are compared with some of the mathematical programming algorithms, the approximation methods and metaheuristic algorithms those reported in the literature. Results demonstrate that the accuracy of the optimization is improved and the convergence rate speeds up.

• 제어로봇시스템학회지
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• 제1권1호
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• pp.50-50
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• 1995

It has been pointed out in the literature that the Routh approximation method for order reduction has limitations in treating transfer functions with the denominator-numerator order difference not equal to one. The purpose of this paper is to present a new algorithm based on the Routh approximation method that can be applied to general rational transfer functions, yielding reduced models with arbitrary order.

• 지구물리와물리탐사
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• 제2권3호
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• pp.142-148
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• 1999

확장된 Born 근사법에 의한 반무한 공간에서의 전자탐사(EM) 3차원 모형반응 알고리듬을 개발하였다. 이 근사법의 정확성을 검토하기 위하여 수직 자기쌍극자(VMD, vertical magnetic dipole)원을 사용하여 자기장의 수평 및 수직성분에 대한 확장된 Born 근사법의 결과를 적분방정식법의 결과와 비교하였다. 그 결과 확장된 Born 근사법과 적분방정식법은 송신원의 주파수가 20 kHz보다 작고 전도도비가 1:10이하에서 정확한 결과를 보였다. 이보다 더 큰 전도도비를 갖는 경우 확장된 Born 근사법의 결과는 적분방정식법의 결과와 약간의 차이를 나타낸다. 따라서, 확장된 Born 근사법의 정확한 결과를 얻기 위해서는 전도도비가 1:10보다 작은 범위에 있어야 한다. 그러나 20 kHz부터 100 kHz의 송신원의 주파수 범위에서는 두 값의 차가 비교적 작기 때문에 확장된 Born 근사법은 EM 3차원 모형반응 알고리듬으로 사용 가능한 것으로 판단된다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
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• pp.177-181
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• 1999

This paper presents an algorithm for building detection from aerial image using segment measure function and line relation. In the detection algorithm proposed, edge detection, linear approximation and line linking are used and then line measure function is applied to each line segment in order to improve the accuracy of linear approximation. Parallelisms, orthogonalities are applied to the extracted liner segments to extract building. The algorithm was applied to aerial image and the buildings were accurately detected.

• Kyungpook Mathematical Journal
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• 제58권3호
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• pp.453-462
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• 2018

In this paper, we present a symbolic formulation of the error obtained due to an approximation of a given function by the mixed-interpolating function. Using the proposed symbolic method, we compute the error evaluation operator as well as the error estimation at any arbitrary point. We also present an algorithm to compute an approximation of a function by the mixed interpolation technique in terms of projector operator. Certain examples are presented to illustrate the proposed algorithm. Maple implementation of the proposed algorithm is discussed with sample computations.

• 전자공학회논문지 IE
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• 제48권1호
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• pp.7-15
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• 2011

본 논문에서는 상관계수를 바탕으로 신호부공간을 추정하는 COPAST(correlation-based projection approximation subspace tracking)의 성능을 향상시키기 위하여 상관계수를 구하는 부분을 순방향 신호 벡터로부터 상관계수를 구하고 동시에 역방향 신호 벡터에서도 상관계수를 구하여 신호 부공간을 추정하는 방법을 제안한다. 또 매번 갱신되는 상관행렬의 안정성을 도모하고자 제곱근 행렬 갱신을 하도록 하였다. 컴퓨터 모의 실험을 통해서 제안된 방법이 기존의 COPAST에 비해서 약 5dB의 신호 부공간 추정 정확도에 향상이 있었음을 확인하였다.

• 한국통신학회논문지
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• 제28권10C호
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• pp.936-941
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• 2003

최근에 소개된 density evolution 기법은 sum-product 알고리즘에서 LDPC 부호가 갖는 성능의 한계를 분석하였다[1]. 또한. Iterative decoding 알고리즘에서 전달되는 정보가 Gaussian 확률분포를 갖는 점을 이용하여 기존의 density evolution 기법을 단순화 시킨 연구결과가 소개되었다[2]. 한편. LDPC 부호의 한계 성능을 sum-product가 아닌 min-sum 알고리즘에서 분석한 결과가 최근에 발표되었다[3]. 본 논문에서는 이러한 일련의 연구 결과를 바탕으로 min-sum 알고리즘을 이용하면서 Gaussian 확률 분포 특성을 이용한 density evolution 기법을 소개한다. 제안된 density evolution 기법은 기존의 방법보다 적은 계산으로 정확한 threshold를 구할 수 있으며. 그 결과가 numerical simulation 결과와 잘 일치함을 나타내었다.