• 대한원격탐사학회지
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• 제21권2호
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• pp.135-143
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• 2005

최근 고해상도 영상의 공급에 있어 물리적 센서 모델의 대안으로서 RPC(Rational Polynomial Camera) 모델이 활발히 이용되고 있다. RPC 모델을 통하여 지상 좌표와 영상 좌표간의 ,기하 관계를 단순하고도 정확하게 묘사할 수 있어 과거 물리적 센서 모델을 통하여만 이루어질 수 있었던 정사보정, 스테레오 영상을 이용한 3차원 좌표 추출 등의 처리가 가능하게 되었다 본 연구에서는 RPCs(Rational Polynomial Coefficients)가 주어진 스테레오 영상으로부터 3차원 좌표를 추출할 수 있는 매우 간단한 방법을 제안하고자 하였다. 제안된 방법은 Downhill Simplex 기법을 이용하는 방법으로서, Downhill Simplex 기법은 함수의 최소값을 찾는데 있어 편미분 계산을 수행하지 않는다는 장점을 가지고 있다. 본 연구에서 제안된 Downhill Simplex 기법을 이용한 RPC 스테레오 영상으로부터의 3차원 좌표 추출 기법은 실제 사용이 가능한 소프트웨어 프로그램으로서 구현되었으며, 서울 지역의 스테레오 IKONOS 영상에 시험 적용되었다. 시험 적용 결과, 본 방법은 비교적 빠르게 3차원 좌표를 계산할 수 있는 것으로 평가되며, RPCs가 주어진 스테레오 영상으로부터 3차원 좌표를 추출할 수 있는 실제적 기술로서 사용이 가능할 것으로 기대된다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제1권1호
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• pp.87-94
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• 2001

Silicon nitride films grown by plasma-enhanced chemical vapor deposition (PECVD) are useful for a variety of applications, including anti-reflecting coatings in solar cells, passivation layers, dielectric layers in metal/insulator structures, and diffusion masks. PECVD systems are controlled by many operating variables, including RF power, pressure, gas flow rate, reactant composition, and substrate temperature. The wide variety of processing conditions, as well as the complex nature of particle dynamics within a plasma, makes tailoring SiN film properties very challenging, since it is difficult to determine the exact relationship between desired film properties and controllable deposition conditions. In this study, SiN PECVD modeling using optimized neural networks has been investigated. The deposition of SiN was characterized via a central composite experimental design, and data from this experiment was used to train and optimize feed-forward neural networks using the back-propagation algorithm. From these neural process models, the effect of deposition conditions on film properties has been studied. A recipe synthesis (optimization) procedure was then performed using the optimized neural network models to generate the necessary deposition conditions to obtain several novel film qualities including high charge density and long lifetime. This optimization procedure utilized genetic algorithms, hybrid combinations of genetic algorithm and Powells algorithm, and hybrid combinations of genetic algorithm and simplex algorithm. Recipes predicted by these techniques were verified by experiment, and the performance of each optimization method are compared. It was found that the hybrid combinations of genetic algorithm and simplex algorithm generated recipes produced films of superior quality.

• 한국소음진동공학회논문집
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• 제12권5호
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• pp.380-388
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• 2002

This paper describes the optimum design for low-pressure steam turbine rotor of 1,000 MW nuclear power plant by using a combined genetic algorithm, which uses both a genetic algorithm and a local concentrate search algorithm (e.g. simplex method). This algorithm is not only faster than the standard genetic algorithm but also supplies a more accurate solution. In addition, this algorithm can find the global and local optimum solutions. The objective is to minimize the resonance response (Q factor) and total weight of the shaft, and to separate the critical speeds as far from the operating speed as possible. These factors play very important roles in designing a rotor-bearing system under the dynamic behavior constraint. In the present work, the shaft diameter, the bearing length, and clearance are used as the design variables. The results show that the proposed algorithm can improve the Q factor and reduce the weight of the shaft and the 1st critical speed.

• Journal of applied mathematics & informatics
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• 제3권1호
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• pp.25-34
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• 1996

Many important large-scale linear programs with special structures lead to special computational procedures which are more ef-ficient than the ordinary procedure of the generalized methods. Prob-lems and their solvers taking advantage of multiple updatings of the basis in the dual simplex type method are presented. Computational results run by the efficient algorithm and a presented. Computational results run by the efficient algorithm and a standard code MINOS for the test problems are compared and analyzed. It is shown that the amount of work for the optimal solution for the prblem can be re-duced by the new algorithm.

• Journal of Electrical Engineering and Technology
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• 제7권1호
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• pp.64-68
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• 2012

In this paper, a design method for minimizing the cogging torque of an Interior Permanent Magnet Motor (IPM) is proposed based on a hybrid algorithm. The suggested optimization algorithm is based on a combination of the Response Surface Method (RSM) and Simplex Method. The results show that the proposed method provides improved characteristics compared to the conventional methods, such as a shorter calculation time and the acquisition of a more correct solution.

• 경영과학
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• 제15권1호
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• pp.49-62
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• 1998

The purpose of this paper is to develope a large-scale simplex method program LPAKO. Various up-to-date techniques are argued and implemented. In LPAKO, basis matrices are stored in a LU factorized form, and Reid's method is used to update LU maintaining high sparsity and numerical stability, and further Markowitz's ordering is used in factorizing a basis matrix into a sparse LU form. As the data structures of basis matrix, Gustavson's data structure and row-column linked list structure are considered. The various criteria for reinversion are also discussed. The dynamic steepest-edge simplex algorithm is used for selection of an entering variable, and a new variation of the MINOS' perturbation technique is suggested for the resolution of degeneracy. Many preprocessing and scaling techniques are implemented. In addition, a new, effective initial basis construction method are suggested, and the criteria for optimality and infeasibility are suggested respectively. Finally, LPAKO is compared with MINOS by test results.

• Steel and Composite Structures
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• 제19권4호
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• pp.995-1009
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• 2015

This study presents design optimization of spot welded structures to attain maximum strength by using the Nelder-Mead (Simplex) method. It is the main idea of the algorithm that the simulation run is executed several times to satisfy predefined convergence criteria and every run uses the starting points of the previous configurations. The material and size of the sheet plates are the pre-assigned parameters which do not change in the optimization cycle. Locations of the spot welds, on the other hand, are chosen to be design variables. In order to calculate the objective function, which is the maximum equivalent stress, ANSYS, general purpose finite element analysis software, is used. To obtain global optimum locations of spot welds a methodology is proposed by modifying the Nelder-Mead (Simplex) method. The procedure is applied to a number of representative problems to demonstrate the validity and effectiveness of the proposed method. It is shown that it is possible to obtain the global optimum values without stacking local minimum ones by using proposed methodology.

• Structural Engineering and Mechanics
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• 제32권5호
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• pp.667-683
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• 2009

FE model-based dynamic analysis has been widely used to predict the dynamic characteristics of civil structures. In a physical point of view, an FE model is unavoidably different from the actual structure as being formulated based on extremely idealized engineering drawings and design data. The conventional model updating methods such as direct method and sensitivity-based parameter estimation are not flexible for model updating of complex and large structures. Thus, it is needed to develop a model updating method applicable to complex structures without restriction. The main objective of this paper is to present the model updating method based on the hybrid genetic algorithm (HGA) by combining the genetic algorithm as global optimization method and modified Nelder-Mead's Simplex method as local optimization method. This FE model updating method using HGA does not need the derivation of derivative function related to parameters and without application of complicated inverse analysis methods. In order to allow its application on diversified and complex structures, a commercial FEA tool is adopted to exploit previously developed element library and analysis algorithms. Moreover, an output-level objective function making use of measurement and analytical results is also presented to update simultaneously the stiffness and mass of the analysis model. The numerical examples demonstrated that the proposed method based on HGA is effective for the updating of the FE model of bridge structures.

• 대한조선학회논문집
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• 제35권2호
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• pp.29-37
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• 1998

물수체의 선형 운동방정식은 형상 설계와 제어기 설계의 지배방정식으로 사용되는 중요한 설계인자이다. 그러나, 경험식, 이론적 계산 및 모형 시험으로부터 획득한 운동방정식 내의 조종 계수들은 오차를 포함하고 있어 해상 시험을 동해 이에 대한 검증을 수행하여야 한다. 본 연구에서는 실측 자료에 대해 병렬 확장 칼만 필터, Nelder & Mead Simplex 탐색법 및 유전적 알고리즘을 적용하여 몰수체의 주요 횡 동요 계수들을 식별/비교하였다. 결론적으로 Nelder & Mead Simplex 탐색법이 사용된 수학 모형과 해상 시험 자료에 대해 가장 만족스런 결과를 주고 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.99-101
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• 2000

Different optimization algorithms have been proposed to solve real and reactive power optimization problems. Most of all, linear programming techniques that employed a simplex method have been extensively used. But, the growth in the size of power systems demands faster and more reliable optimization techniques. An Interior Point(IP) mehod is based on an interior point approach to aim the solution trajectory toward the optimal point and is converged to the solution faster than the simplex method. This paper deals with the use of Successive Linear Programming(SLP) for the solution of the Security Constrained Economic Dispatch(SCED) problem. This problem is solved using the IP method. A comparison with simplex method shows that the interior point technique is reliable and faster than the simplex algorithm.