• 한국정보통신학회논문지
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• 제8권6호
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• pp.1218-1227
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• 2004

멀티-도메인 공학시스템은 전기, 기계, 유압, 열등의 도메인을 포함하며, 시스템 구성이 복잡하여 설계에 많은 어려움을 가지고 있다. 최적의 설계를 위해서는 각 도메인에 대한 통합된 설계 방법과 자동적이고 효율적인 탐색방법이 요구된다. 본 논문은 도메인에 독립적인 본드 그래프(bond graph)와 대규모 공간 해의 탐색에 접합한 진화 알고리즘의 일종인 Genetic Programming(유전 프로그래밍, GP)를 결합하여 멀티 도메인 동적 시스템에 대한 디자인 해를 자동적으로 생성해주는 설계 방법을 제시하였다. 제안된 설계방법의 효용성을 입증하기 위해서 고유값(eigenvalue) 설계 문제가 실험되었고, 서로 다른 태아모델을 가진 고유값의 집합이 사용되었다.

• 한국지능시스템학회논문지
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• 제10권2호
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• pp.161-167
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• 2000

본 논문에서는 양방향 연상 기능을 효과적으로 수행할 수 있는 BAM(bidirectional associative memory)의 설계방법론을 제안한다. 먼저 BAM의 성질에 관한 이론적 고찰을 바탕으로 하여 주어진 패턴 쌍을 안정하게 그리고 높은 오차수정율(error correction ratio)을 가지고 저장할 수 있는 BAM을 찾는 문제를 제약조건이 있는 최적화 문제로 공식화한다 다음과정에서 이 최적화 문제를 GEVP(generalized eigenvalue problem)로 변환함으로써 최근에 개발된 내부점 방법(interior point method)을 통하여 해가 구해질 수 있도록 한다. 제안된 설계 방법론의 적용가능성은 예제를 통해 확인된다.

• 한국생산제조학회지
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• 제22권1호
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• pp.63-69
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• 2013

In order to find the optimum design of structures that have characteristic natural frequency range, a numerical optimization method to solving eigenvalue problems is a widely used approach. However in the most cases, it is difficult to decide the accurate thickness and shape of structures that have allowable natural frequency in design constraints. Parallel analysis algorithm involving the feasible direction optimization method and Rayleigh-Ritz eigenvalue solving method is developed. The method is implemented by using finite element method. It calculates the optimal thickness and the thickness ratio of individual elements of the 2-D plane element through a parallel algorithm method which satisfy the design constraint of natural frequency. As a result this method of optimization for natural frequency by using finite element method can determine the optimal size or its ratio of geometrically complicated shape and large scale structure.

• 한국항공운항학회지
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• 제15권2호
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• pp.9-17
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• 2007

A Green's function approach based on the laminate theory is adopted for solving the two-dimensional unsteady temperature field and the associated thermal stresses in an infinite plate made of functionally graded material (FGM). All material properties are assumed to depend only on the coordinate x (perpendicular to the surface). The unsteady heat conduction equation is formulated into an eigenvalue problem by making use of the eigenfunction expansion theory and the laminate theory. The eigenvalues and the corresponding eigenfunctions obtained by solving an eigenvalue problem for each layer constitute the Green's function solution for analyzing the two-dimensional unsteady temperature. The associated thermoelastic field is analyzed by making use of the thermal stress function. Numerical analysis for a FGM plate is carried out and effects of material properties on unsteady thermoelastic behaviors are discussed.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제25회 추계학술대회논문집
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• pp.422-425
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• 2005

가로 등방성 복합재료에서 반사되거나 굴절된 파동의 속도와 입자방향, 그리고 진폭을 운동방정식과 구성방정식 그리고 파동수와 진동수로 표현된 변위식을 사용하여 구하였다. Snell 법칙을 사용하여 Eigenvalue 문제를 풀어 파동속도를 구하였으며 그 결과는 T300 Carbon fiber/5208 Epoxy 재료 성질을 이용하여 검증하였다. 이러한 분석은 수분 침수 C-scan을 이용하여 가로등방성 복합재료의 결점을 찾아내는데 응용될 수 있다.

• KIEE International Transactions on Power Engineering
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• 제5A권4호
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• pp.344-349
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• 2005

In conventional small signal stability analysis, the system is assumed to be invariant and the state space equations are used to calculate the eigenvalues of the state matrix. However, when a system contains switching elements such as FACTS equipments, it becomes a non-continuous system. In this case, a mathematically rigorous approach to system small signal stability analysis is performed by means of eigenvalue analysis of the system's periodic transition matrix based on the discrete system analysis method. In this paper, the RCF (Resistive Companion Form) method is used to analyze the small signal stability of a non-continuous system including switching elements. Applying the RCF method to the differential and integral equations of the power system, generator, controllers and FACTS equipments including switching devices should be modeled in the form of state transition equations. From this state transition matrix, eigenvalues that are mapped into unit circles can be computed precisely.

• 대한기계학회논문집
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• 제18권7호
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• pp.1840-1850
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• 1994

Enhancement of numerical algorithms for low speed compressible flow will be considered. Contemporary time-marching algorithm has been widely accepted and applied as the method of choice for transonic, supersonic and hypersonic flows. In the low Mach number regime, time-marching algorithms do not fare as well. When the velocity is small, eigenvalues of the system of compressible equations differ widely so that the system becomes very stiff and the convergence becomes very slow. This characteristic can lead to difficulties in computations of many practical engineering problems. In the present approach, the time-derivative preconditioning method will be used to control the eigenvalue stiffness and to extend computational capabilities over a wide range of flow conditions (from very low Mach number to supersonic flow). Computational capabilities of the above algorithm will be demonstrated through computation of a variety of practical engineering problems.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.10-10
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• 2000

Eigenstructure assignment is a typical method with the capability of the consideration of the specifications in time-domain in designing a 1]near control system. In general eigenstructure assignment such that all the desired eigenvalues are exactly assigned to the closed-loop system, the assignment of the eigenvectors is very restrictive. However if the arbitrary point in a certain area as an eigenvalue is allowed to be assigned t the closed-loop system, the assignment of the eigenvector corresponding to this eigenvalue can be much less restrictive. In this paper, the flexible eigenstructure assignment that can assign more closely the desired eigenvector to the closed-loop system by using an optimization technique is proposed.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
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• pp.410-415
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• 2000

In this paper feasible direction method which is one of the optimization method is adopted to natural frequency optimization. In order to find the optimum design of structures that have characteristic natural frequency range, a numerical optimization method to solving eigenvalue problems is a widely used approach. However most cases, it is difficult to decide the accurate thickness and shape of structures that have allowable natural frequency in design constraints. Parallel analysis algorithm involving the feasible direction optimization method and Rayleight-Ritz eigenvalue solving method is developed. The method is implemented by using finite element method. It calculated the optimal thickness and the thickness ratio of each element of 2-D plane element through the parallel algorithm method which satisfy the design constraint of natural frequency.

• 한국추진공학회지
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• 제10권2호
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• pp.62-69
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• 2006

가로 등방성 복합재료에서 반사되거나 굴절된 파동의 속도와 입자방향, 그리고 진폭을 운동방정식과 구성방정식 그리고 파동수와 진동수로 표현된 변위식을 사용하여 구하였다. Snell 법칙을 사용하여 Eigenvalue 문제를 풀어 파동속도를 구하였으며 그 결과는 T300 Carbon fiber/5208 Epoxy 재료 성질을 이용하여 검증하였다. 이러한 분석은 수분 침수 C-scan을 이용하여 가로등방성 복합재료의 결점을 찾아내는데 응용될 수 있다.