• 한국인터넷방송통신학회논문지
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• 제17권5호
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• pp.157-163
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• 2017

데이터 탐색법 중 가장 널리 알려진 이진법은 평균과 최악의 경우 $O(log_2n)$, 보간법은 평균 $O(log_2log_2n)$, 최악의 경우 O(n)의 수행 복잡도를 갖고 있다. 또한 기존의 보간탐색법은 사전정보없이 킷값이 확률적으로 위치한 정보에 근거하여 탐색을 한다. 본 논문에서는 데이터의 MSB 인덱스를 블록으로 하는 블록탐색법으로 해당 블록범위를 결정하고, 블록 내에서는 보간법을 적용하여 탐색하는 하이브리드 블록과 보간탐색 알고리즘을 제안한다. 제안된 알고리즘은 블록탐색법의 사전 정보를 활용하여 탐색범위를 축소시키고 축소된 탐색범위내에서 무정보 방법으로 탐색하는 방법으로 평균과 최악의 경우 모두 수행복잡도는 $O(log_2log_2n_i)$, $n_i{\simeq}0.1n$으로 보간탐색법의 평균 수행복잡도에 비해 10배 정도 시간을 단축시킬 수 있다.

• 대한기계학회논문집
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• 제19권2호
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• pp.433-442
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• 1995

For the line search of a multi-variable optimization, an efficient algorithm is presented. The algorithm sequentially employs several polynomial approximations such as 2-point quadratic interpolation, 3-point cubic interpolation/extrapolation and 4-point cubic interpolation/extrapolation. The order of polynomial function is automatically increased for improving the accuracy of approximation. The method of approximation (interpolation or extrapolation) is automatically switched by checking the slope information of the sample points. Also, for selecting the initial step length along the descent vector, a new approach is presented. The performance of the proposed method is examined by solving typical test problems such as mathematical problems, mechanical design problems and dynamic response problems.

• 소성∙가공
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• 제6권5호
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• pp.416-424
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• 1997

In the present study, a contact search and check algorithm for general tool surface described by triangular FE patch is proposed. To improve numerical stability, SEAM element using the linear Coons interpolation has been used. To check the proposed algorithm, both clover cup and L-shape cup deep drawing processes are calculated. The computed results shows that the proposed contact algorithm can be successfully applied for sheet metal forming processes with general shaped tools.

• 한국전산유체공학회지
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• 제17권4호
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• pp.32-40
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• 2012

Efficient Global Optimization (EGO) method is a global optimization technique which can select the next sample point automatically by infill sampling criteria (ISC) and search for the global minimum with less samples than what the conventional global optimization method needs. ISC function consists of the predictor and mean square error (MSE) provided from the kriging model which is a stochastic metamodel. Also the constrained EGO method can minimize the objective function dealing with the constraints under EGO concept. In this study the constrained EGO method applied to the RAE2822 airfoil shape design formulated with the constraint. But the noisy CFD data caused the kriging model to fail to depict the true function. The distorted kriging model would make the EGO deviate from the correct search. This distortion of kriging model can be handled with the interpolation(p=free) kriging model. With the interpolation(p=free) kriging model, however, the search of EGO solution was stalled in the narrow feasible region without the chance to update the objective and constraint functions. Then the accuracy of EGO solution was not good enough. So the three-step search method was proposed to obtain the accurate global minimum as well as prevent from the distortion of kriging model for the noisy constrained CFD problem.

• 한국유체기계학회 논문집
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• 제2권1호
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• pp.29-34
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• 1999

To develop the efficient numerical optimization method for the design of an airfoil, an evaluation of various methods coupled with two-dimensional Naviev-Stokes analysis is presented. Simplex method and Hook-Jeeves method we used as direct search methods, and steepest descent method, conjugate gradient method and DFP method are used as indirect search methods and are tested to determine the search direction. To determine the moving distance, the golden section method and cubic interpolation method are tested. The finite volume method is used to discretize two-dimensional Navier-Stokes equations, and SIMPLEC algorithm is used for a velocity-pressure correction method. For the optimal design of two-dimensional airfoil, maximum thickness, maximum ordinate of camber line and chordwise position of maximum ordinate are chosen as design variables, and the ratio of drag coefficient to lift coefficient is selected as an objective function. From the results, it is found that conjugate gradient method and cubic interpolation method are the most efficient for the determination of search direction and the moving distance, respectively.

• 정보처리학회논문지D
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• 제12D권3호
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• pp.345-354
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• 2005

서브시퀀스 매칭은 데이터 마이닝 분야에서 중요한 연산 중의 하나이다. 기존의 서브시퀀스 매칭 알고리즘들은 하나의 인덱스만을 사용하여 검색을 수행하며, 인덱스를 생성하기 위하여 데이터 시퀀스로부터 추출한 윈도우의 크기와 질의 시퀀스의 길이 간의 차이가 커질수록 검색 성능이 급격히 저하된다. 본 논문에서는 이러한 문제점을 해결하기 위하여 인덱스 보간법에 기반한 새로운 서브시퀀스 매칭 기법을 제안한다. 인덱스 보간법이란 하나 이상의 인덱스를 구축하고 주어진 질의 시퀀스의 길이에 따라 적절한 인덱스를 선택하여 검색을 수행하는 기법이다. 본 논문에서는 먼저 사전 실험을 통하여 서브시퀀스 매칭을 수행하는 데에 있어 질의 시퀀스 길이와 윈도우 크기 간의 차이로 인한 성능의 변화를 관찰하고, 이 관찰을 통하여 물리적 데이터베이스 설계 관점에서 질의 시퀀스의 길이 분포에 따른 검색 비용 공식을 산출한다. 다음에, 윈도우 크기 효과에 의한 성능 저하를 개선하기 위해 인덱스 보간법에 기반한 새로운 검색 기법을 제안한다. 또한, 검색 비용 공식에 기반하여 제안된 검색 기법의 성능을 최적화할 수 있도록 다수의 인덱스를 구성하는 알고리즘을 제시한다. 마지막으로, 실제 데이터와 합성 데이터를 이용한 여러 가지 실험을 통하여 제안된 기법의 우수성을 검증한다.

• 한국농공학회지
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• 제40권3호
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• pp.103-112
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• 1998

In this study, database schema which is capable of maintaining various design-knowledge and applicable to the structural designs has been presented. Futhermore, by utilizing the database system, RECODSS (REinforced COncrete Design Support System) was developed as well. Knowledge-base that were formulated from the document is constructed by applying the concrete standard specifications of Korea from 1989. The basic drawing was prepared by $AutoCAD^TM$. As an inference in the preliminary design, the certainty function and the interpolation function were presented. The certainty function is made by assuming linear relations between each data while referencing $MYCIN^TM$ (expert systems). Nevertheless, the interpolation function was made by utilizing the linear Lagrange interpolation. For the search of the design-knowledge, fast search algorithm and full-text search algorithm were used, however, the design engine was programmed with C language. RECODSS was applied for designing a slab and a beam member. And the results were compared with the existing results. In conclusion, RECODSS was able to efficiently manage various design knowledge and to introduce stable design results.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.803-804
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• 2008

In this paper, we propose an edge dependent interpolation (EDI) method based on adaptive search range. The proposed EDI method uses the vector matching to determine the edge direction, and the vector matching process is terminated when the previous sum of absolute difference (SAD) is smaller than the next one. The adaptive search range method enables the EDI algorithm to estimate edge direction more accurately and to reduce the computational complexity. The experimental results show that the proposed method produces better performance than conventional algorithms.

• EDISON SW 활용 경진대회 논문집
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• 제5회(2016년)
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• pp.183-189
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• 2016

In this paper, an optimization study on a helicopter rotor blade cross-section was made. Generalization was made to the baseline cross-section to simplify the analysis. To have better performance in aeroelastic response, with the aerodynamic center being the origin of the baseline, the distance between aerodynamic center and shear center, and the distance between mass center and shear center of the blade were minimized. For efficient searching of optimum solutions over the design space, grid search method, which is a method of graphical search was used. Two design variables, radius of balancing weight at leading edge, and offset of the spar from leading edge were selected for the study. Cubic spline interpolation method was used to accommodate searching of the optimum solution. 2-Leveled searching system was devised in accordance with the interpolation method. Optimum solution was found to show 6% decrease in both distance between aerodynamic center and shear center, and mass center and shear center to the baseline.

• 대한전자공학회논문지SP
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• 제42권5호
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• pp.63-72
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• 2005

본 논문에서 삼각대 위에 고정시킨 카메라를 회전시켜 취득한 비디오 시퀀스로부터 파노라마 영상을 구성하는 새로운 방법을 제안한다. 제안한 방법은 비디오 시퀀스 중에서 실제로 사용할 프레임을 자동으로 선택하는 단계와 파노라마 영상을 구성하는 모자이킹 단계로 나누어진다. 파노라마 영상을 구성하는데 필요한 프레임은 연속된 프레임 간의 중첩 비율 정보를 이용한 보간 검색을 통해 선택된다 이 방법은 카메라의 속도에 상관없이 적절한 프레임을 고속으로 검색할 수 있다. 모자이킹 단계에서는 4쌍의 특징점을 사용하는 사영 변환식(projective transform)을 이용한다. 기존의 연구에서는 특징점을 화소 기반의 정보만을 이용하여 추출하였지만, 본 논문에서 제안한 방법은 특징점의 위치까지 고려하여 사영 변환식의 정확도를 높였다. 제안한 방법은 다양한 영상 시퀀스에 적용하여 실험하였고, 그 결과 모든 영상에 대해서 좋은 화질의 파노라마 영상을 생성하였다.