• ETRI Journal
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• 제39권6호
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• pp.782-793
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• 2017

This paper considers the use of the Partial Transmit Sequence (PTS) technique to reduce the Peak-to-Average Power Ratio (PAPR) of an Orthogonal Frequency Division Multiplexing signal in wireless communication systems. Search complexity is very high in the traditional PTS scheme because it involves an extensive random search over all combinations of allowed phase vectors, and it increases exponentially with the number of phase vectors. In this paper, a suboptimal metaheuristic algorithm for phase optimization based on an improved harmony search (IHS) is applied to explore the optimal combination of phase vectors that provides improved performance compared with existing evolutionary algorithms such as the harmony search algorithm and firefly algorithm. IHS enhances the accuracy and convergence rate of the conventional algorithms with very few parameters to adjust. Simulation results show that an improved harmony search-based PTS algorithm can achieve a significant reduction in PAPR using a simple network structure compared with conventional algorithms.

• Structural Engineering and Mechanics
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• 제29권4호
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• pp.391-410
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• 2008

In this article, a harmony search algorithm is presented for optimum design of steel frame structures. Harmony search is a meta-heuristic search method which has been developed recently. It is based on the analogy between the performance process of natural music and searching for solutions of optimization problems. The design algorithms obtain minimum weight frames by selecting suitable sections from a standard set of steel sections such as American Institute of Steel Construction (AISC) wide-flange (W) shapes. Stress constraints of AISC Load and Resistance Factor Design (LRFD) and AISC Allowable Stress Design (ASD) specifications, maximum (lateral displacement) and interstorey drift constraints, and also size constraint for columns were imposed on frames. The results of harmony search algorithm were compared to those of the other optimization algorithms such as genetic algorithm, optimality criterion and simulated annealing for two planar and two space frame structures taken from the literature. The comparisons showed that the harmony search algorithm yielded lighter designs for the design examples presented.

• Journal of Information Processing Systems
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• 제15권2호
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• pp.433-439
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• 2019

Artificial bee colony algorithm is a strong global search algorithm which exhibits excellent exploration ability. The conventional ABC algorithm adopts employed bees, onlooker bees and scouts to cooperate with each other. However, its one dimension and greedy search strategy causes slow convergence speed. To enhance its performance, in this paper, we abandon the greedy selection method and propose an artificial bee colony algorithm with special division and intellective search (ABCIS). For the purpose of higher food source research efficiency, different search strategies are adopted with different employed bees and onlooker bees. Experimental results on a series of benchmarks algorithms demonstrate its effectiveness.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.1097-1100
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• 1999

Due to the significant computation of full search in motion estimation, extensive research in fast motion estimation algorithms has been carried out. However, most of the algorithms have the degradation in predicted images compared with the full search algorithm. To reduce an amount of significant computation while keeping the same prediction quality of the full search, we propose a fast block-matching algorithm based on gradient magnitude of reference block without any degradation of predicted image. By using Taylor series expansion, we show that the block matching errors between reference block and candidate block are proportional to the gradient magnitude of matching block. With the derived result, we propose fast full search algorithm with adaptively determined scan direction in the block matching. Experimentally, our proposed algorithm is very efficient in terms of computational speedup and has the smallest computation among all the conventional full search algorithms. Therefore, our algorithm is useful in VLSI implementation of video encoder requiring real-time application.

• 전자공학회논문지B
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• 제33B권8호
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• pp.81-95
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• 1996

In this paper, we propose a motio estiamtion algorithm using low-resolution quantization to reduce the computation of the full search algorithm. The proposed algorithm consists of the low-resolution search which determins the candidate motion vectors by comparing the low-resolution image and the full-resolution search which determines the motion vector by comparing the full-resolution image on the positions of the candidate motion vectors. The low-resolution image is generated by subtracting each pixel value in the reference block or the search window by the mean of the reference block, and by quantizing it is 2-bit resolution. The candidate motion vectors are determined by counting the number of pixels in the reference block whose quantized codes are unmatched to those in the search window. Simulation results show that the required computational cost of the proposed algorithm is reduced to 1/12 of the full search algorithm while its performance degradation is 0.03~0.12 dB.

• 제어로봇시스템학회논문지
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• 제3권2호
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• pp.156-161
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• 1997

In this thesis, based on Genetic Algorithm, a new route search algorithm is presented to search an optimal route between the origin and the destination in intelligent route guidance systems in order to minimize the route traveling time. The proposed algorithm is effectively employed to complex road networks which have diverse turn constrains, time-delay constraints due to cross signals, and stochastic traffic volume. The algorithm is also shown to significantly promote search efficiency by changing the population size of path individuals that exist in each generation through the concept of age and lifetime to each path individual. A virtual road-traffic network with various turn constraints and traffic volume is simulated, where the suggested algorithm promptly produces not only an optimal route to minimize the route cost but also the estimated travel time for any pair of the origin and the destination, while effectively avoiding turn constraints and traffic jam.

• 한국지능시스템학회논문지
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• 제8권3호
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• pp.71-79
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• 1998

본 논문은 유전알고리즘과 random tabu 탐색법을 조합한 새로운 최적화 알고리즘을 제안한다. 유전알고리즘과 전역적인 최적해에 대한 탐색능력이 우수하고, random tabu 탐색법은 최적해에의 수렴속도가 매우 빠른 알고리즘이다. 본 논문에서는 이 두 알고리즘의 장점을 이용해서 수렴정도와 수렴속도가 더욱 향상된 최적알고리즘을 제안하여 알고리즘의 수렴성능을 조사하고, 실제 최적화문제로서 지진응답을 최소로 하기위한 배관지지대의 최적배치문제에 적용하여 기존의 방법과 비교를 통하여 유용성을 검토하였다.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제10권1호
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• pp.57-65
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• 2004

서로 다른 형태와 크기를 가지는 탐색패턴과 움직임 벡터의 분포는 블록 정합 알고리즘에서 탐색 속도와 화질을 좌우하는 중요한 요소이다. 본 논문에서는 단위 다이아몬드패턴과 납작한 육각패턴을 이용한 새로운 고속 블록 정합 알고리즘을 제안한다. 이 알고리즘은 단위 다이아몬드패턴을 이용하여 적은 탐색점으로 움직임이 적은 벡터를 우선 찾은 다음에 움직임이 큰 벡터에 대해서는 납작한 육각패턴을 이용하여 고속으로 움직임 벡터를 찾게 하였다. 실험결과, 제안된 알고리즘은 육각패턴 탐색 알고리즘에 비하여 움직임 벡터 예측의 속도에 있어서 약 11∼51%의 높은 성능 향상을 보였으며 화질 또한 PSNR 기준으로 약 0.05∼0.74㏈의 향상을 보였다.

• 방송공학회논문지
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• 제12권3호
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• pp.278-288
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• 2007

본 논문에서는 비디오 부호화의 움직임 예측에 사용되는 블록 정합 알고리즘의 계산량을 줄이는 고속 전영역 탐색 알고리즘을 제안한다. 블록 정합 알고리즘에서 사용되는 기존의 나선형 탐색 알고리즘은 탐색 영역의 중심에서 시작하여 탐색 지점을 화소 단위로 이동화면서 움직임 예측을 수행하기 때문에 움직임이 적은 영상에 적합하다. 본 논문에서는 움직임이 작은 영상 뿐 아니라 움직임이 많은 영상에서도 효율적인 움직임 예측을 하기 위해 다음과 같은 알고리즘을 제안한다. 먼저 초기 문턱 값을 계산함에 있어서 확장된 예측기를 사용하여 보다 최소값에 근사한 문턱값을 계산한다. 그리고 탐색영역을 블록으로 세분화 한 후 각 영역을 새로운 탐색 순서에 따라 움직임 예측을 수행하고 방향성에 따라 영역을 재분할한다. 재분할된 영역이 가지는 방향성에 따라 방향 지향적인 탐색 순서를 적용한다. 실험 결과에서 제안하는 알고리즘이 기존의 나선형 전영역 탐색 알고리즘에 비해 객관적인 화질의 열화 없이 계산량이 평균적으로 약 94% 감소하는 것을 확인할 수 있다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(4)
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• pp.183-186
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• 2000

Motion estimation technique has been used to increase video compression rates in motion video applications. One of the important algorithms to implement the motion estimation technique is search algorithm. Among many search algorithms, the H.263 adopted the Nearest Neighbors algorithm for fast search. In this paper, motion estimation block for the Nearest Neighbors algorithm is designed on FPGA and coded using VHDL and simulated under the Xilinx foundation environments. In the experiment results, we verified that the algorithm was properly designed and performed on the Xilinx FPGA(XCV300Q240)