• 전자공학회논문지
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• 제50권1호
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• pp.9-14
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• 2013

본 논문에서는 고속 시변 채널 OFDM을 위한 저복잡도 양방향 탐색 순차적 간섭 제거(Successive Interference Cancellation: SIC) 방식을 제안한다. SIC에서는 오류 전파에 의한 성능 저하 가능성으로 인하여 심볼 블록 내에서의 심볼 검출 순서가 전체적인 성능에 큰 영향을 미친다. 본 논문에서는 조건 심볼오류확률(Conditional Symbol Error Probability: CSEP)을 기준으로 최초로 검출되는 심볼을 결정하고, 그 다음 검출될 심볼은 기검출된 심볼군의 경계에서 양방향으로 탐색하여 CSEP를 갱신한 후 결정하는 방식을 이용한다. 컴퓨터 모의실험 결과 제안된 방식은 기존 방식과 비교하여 높은 SNR 영역에서 거의 동일한 계산량으로 보다 우수한 성능을 나타낸다. 제안된 방식은 비트에러율 = $10^{-5}$에서 성능 상한치인 정합필터 한계(Matched Filter Bound: MFB)에 2dB 이내로 접근하는 성능을 가진다.

• 대한기계학회논문집A
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• 제26권2호
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• pp.406-414
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• 2002

A new approach, referred to as a successive zooming genetic algorithm (SZGA), is Proposed for identifying a global solution for continuous optimization problems. In order to improve the local fine-tuning capability of GA, we introduced a new method whereby the search space is zoomed around the design point with the best fitness per 100 generation. Furthermore, the reliability of the optimized solution is determined based on the theory of probability. To demonstrate the superiority of the proposed algorithm, a simple genetic algorithm, micro genetic algorithm, and the proposed algorithm were tested as regards for the minimization of a multiminima function as well as simple functions. The results confirmed that the proposed SZGA significantly improved the ability of the algorithm to identify a precise global minimum. As an example of structural optimization, the SZGA was applied to the optimal location of support points for weight minimization in the radial gate of a dam structure. The proposed algorithm identified a more exact optimum value than the standard genetic algorithms.

• Structural Engineering and Mechanics
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• 제30권2호
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• pp.135-146
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• 2008

This study utilizes the fine-tuning and small-digit characteristics of the successive zooming genetic algorithm (SZGA) to propose a method of structural damage detection in a continuum structure, where the differences in the natural frequencies of a structure obtained by experiment and FEM are compared and minimized using an assumed location and extent of structural damage. The final methodology applied to the structural damage detection is a kind of pseudo-discrete-variable-algorithm that counts the soundness variables as one (perfectly sound) if they are above a certain standard, such as 0.99. This methodology is based on the fact that most well-designed structures exhibit failures at some critical point due to manufacturing error, while the remaining region is free of damage. Thus, damage of 1% (depending on the given standard) or less can be neglected, and the search concentrated on finding more serious failures. It is shown that the proposed method can find out the exact structural damage of the monitored structure and reduce the time and amount of computation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권5호
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• pp.2081-2101
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• 2016

Successive interference cancellation (SIC) is considered to be a promising technique to mitigate multi-user interference and achieve concurrent uplink transmissions, but the optimal power allocation (PA) issue for SIC users is not well addressed. In this article, we focus on the optimization of the PA ratio of users on an SIC channel and analytically obtain the optimal PA ratio with regard to the signal-to-interference-plus-noise ratio (SINR) threshold for successful demodulation and the sustainable demodulation error rate. Then, we design an efficient resource allocation (RA) scheme using the obtained optimal PA ratio. Finally, we compare the proposal with the near-optimum RA obtained by a simulated annealing search and the RA scheme with random PA. Simulation results show that our proposal achieves a performance close to the near-optimum and much higher performance than the random scheme in terms of total utility and Jain's fairness index. To demonstrate the applicability of our proposal, we also simulate the proposal in various network paradigms, including wireless local area network, body area network, and vehicular ad hoc network.

• 전자공학회논문지B
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• 제33B권1호
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• pp.161-169
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• 1996

본 논문에서는 동영상 압축의 핵심 기술인 움직임 벡터 추정에 있어서 신경 회로망을 이용한 벡터 양자화에 의해 탐색 영역을 예측하는 방법을 제안한다. 훈련영상을 입력으로 하여 전역 탐색법 등에 의하여 구해진 움직임 벡터를 이용하여 움직임 벡터 코드 북을 생성하고 이를 예측 탐색 점으로 이용한다. 움직임 벡터 코드 북을 생성하기 위해서 병렬 처리 특성과 다양한 학습 알고리즘을 갖는 신경 회로망을 이용하였다. 제안된 방법은 움직임 벡터들의 높은 공간적 상관성을 이용하게 되고 결과적으로 적은 탐색 점으로 움직임 벡터를 추정할 수 있으므로 계산량을 줄일 수 있을 뿐 아니라 움직임 벡터를 표현하기 위해 소요되는 비트 수도 크게 줄일 수 있다. 모의 실험을 통하여 제안된 방식이 기존의 고속 블록 매칭 알고리즘보다 우수함을 보였다.

• 한국농공학회논문집
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• 제46권4호
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• pp.65-71
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• 2004

Stress Path Search Model of Evolutionary Structural Successive Optimization (SPSMESO) using Triangular Irregular Network(TIN) was developed for improving over burden at initial design of ESO and strict stress direction of strut-and-tie model and truss model. TIN was applied for discretizing structures in flexible stress path and segments of TIN was analyzed as one-dimensional line element for calculating stress. Finally, stress path was searched using ESO algorithm. SPSMESO was efficient to express the direction of stress for 2D structure and time saving.

• 제어로봇시스템학회논문지
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• 제3권1호
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• pp.46-51
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• 1997

The optimal control of a continuous process has been performed using genetic algorithms(GAs). GAs are robust and easily applicable for complex and highly nonlinear problems. We introduce the heuristics 'dynamic range' which reduces the search space dramaticaly keeping the robust search of GAs. GAs with dynamic range show the better performance than SQP(Successive Quadratic Programing) method which converges to a local minimum. The proposed methology has been applied to the optimal control of the continuous MMA-VA copolymerization reactor for the production of the desired molecular wieght and the composition of VA in dead copolymer.

• Journal of applied mathematics & informatics
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• 제23권1_2호
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• pp.269-279
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• 2007

This paper describes a direct search method for a class of linearly constrained optimization problem. Through research we find it can be treated as an unconstrained optimization problem. And with the decrease of dimension of the variables need to be computed in the algorithms, the implementation of convergence to KKT points will be simplified to some extent. Convergence is shown under mild conditions which allow successive frames to be rotated, translated, and scaled relative to one another.

• Structural Engineering and Mechanics
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• 제34권5호
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• pp.597-609
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• 2010

A problem formulation and solution methodology for design optimization of laminated thin-walled composite beams of generic section is presented. Objective functions and constraint equations are given in the form of beam stiffness. For two different problems one for open section and the other for closed section, the objective function considered is bending stiffness about x-axis. Depending upon the case, one can consider bending, torsional and axial stiffnesses. The different search and optimization algorithm, known as Evolution Strategies (ES) has been applied to find the optimal fibre orientation of composite laminates. A multi-level optimization approach is also implemented by narrowing down the size of search space for individual design variables in each successive level of optimization process. The numerical results presented demonstrate the computational advantage of the proposed method "Evolution strategies" which become pronounced to solve optimization of thin-walled composite beams of generic section.

• 반도체디스플레이기술학회지
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• 제12권3호
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• pp.13-18
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• 2013

Motion estimation is a key technique of modern video processing that significantly improves the coding efficiency significantly by exploiting the temporal redundancy between successive frames. Thread-level parallelism is a promising method to accelerate the motion estimation process for multithreading general-purpose processors. In this paper, we propose a parallel motion estimation algorithm which parallelizes the motion search process of the current H.264/AVC encoder. The proposed algorithm is implemented using the OpenMP application programming interface (API) and can be easily integrated into the current encoder. The experimental results show that the proposed parallel algorithm can reduce the processing time of the motion estimation up to 65.08% without any penalty in the rate-distortion (RD) performance.