• Journal of the Korea Institute of Building Construction
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• v.17 no.4
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• pp.369-375
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• 2017

This study suggests PSO(Particle Swarm Optimization) algorithm that optimizes the snowplow route allocation and the location of the snow control material storage to improve the efficiency in snow removal works. The modified PSO algorithm for improving the search capacity is proposed, and this study suggests the solution representation, the parameter setting, and the fitness function for the given optimization problems. Computational experiments in real-world case are carried out to justify the proposed method and compared with the traditional PSO algorithms. The results show that the proposed algorithms can find the better solution than the traditional PSO algorithms by searching for the wider solution space without falling into the local optima. The finding of this study is efficiently employed to solve the optimization of the snowplow route allocation by minimizing the workload of each snowplow to search the location of the snow control material storage as well.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.41-44
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• 2001

삼각형 메쉬(triangular mesh)로 이루어진 삼차원 영상의 큰 데이터량을 줄이기 위한 메쉬 부호화의 연구가 활발히 진행되고 있다. 그리고, 최근에는 삼차원 부호화 데이터의 네트워크 전송 문제가 대두되어, 점진적 부호화(proressive mesh compression)에 대한 알고리듬들도 제안되고 있다. 본 논문은 꼭지점의 위치 정보 및 간략화 과정의 꼭지점 패턴(vertex pattern) 규칙을 이용하여, 기존의 점진적 부호화 알고리듬의 부호화 성능을 개선한 알고리듬을 제안한다. 꼭지점의 위치 정보를 이용하여 기존의 알고리듬에 비해 낮은 엔트로피(entropy)를 얻었으며, 꼭지점 패턴 정보를 이용하여 복원시 분할 꼭지점(split vertex)의 탐색 범위를 한정하였다. 전산 모의 실험을 통해, 제안하는 알고리듬이 기존의 점진적 메쉬 부호화 연구에 비해, 연결 정보 부호화에서 대략 30%정도 향상된 부호화 성능을 가짐을 확인할 수 있었다.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06c
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• pp.71-74
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• 1998

HMM (hidden Markov model)을 이용한 음성인식은 현재 가장 널리 쓰여지고 있는 방법으로, 이 중 CDHMM (continuous observation density HMM)은 상태에서 관측심볼확률을 연속확률밀도를 사용하여 표현한다. 본 논문에서는 가우스 혼합밀도함수를 사용하는 CDHMM의 상태천이확률과, 관측심볼확률을 표현하기 위한 인자인 평균벡터, 공분산 행렬, 가지하중값을 유전자 알고리듬을 사용하여 최적화하는 방법을 제안하였다. 유전자 알고리듬은 매개변수 최적화문제에 대하여 자연의 진화원리를 모방한 알고리듬으로, 염색체 형태로 표현된 개체군 (population) 중에서 환경에 대한 적합도 (fitness)가 높은 개체가 높은 확률로 살아남아 재생 (reproduction)하게 되며, 교배 (crossover)와 돌연변이 (mutation) 연산 후에 다음 세대 개체군을 형성하게 되고, 이러한 과정을 반복하면서 최적의 개체를 구하게 된다. 본 논문에서는 상태천이확률, 평균벡터, 공분산행렬, 가지하중값을 부동소수점수 (floating point number)의 유전자형으로 표현하여 유전자 알고리듬을 수행하였다. 유전자 알고리듬은 복잡한 탐색공간에서 최적의 해를 찾는데 효과적으로 적용되었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7A
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• pp.1080-1089
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• 1999

The union upper bounds to the bit error probability of maximum likelihood(ML) soft-decoding of parallel concatenated convolutional codes(PCCC) and serially concatenated convolutional codes(SCCC) can be evaluated through the weight enumerating function(WEF). This union upper bounds become the lower bounds of the BER achievable when iterative decoding is used. In this paper, to compute the WEF, an efficient error event search algorithm which is a combination of stack algorithm and bidirectional search algorithm is proposed. By computor simulation, it is shown that the union boounds obtained by using the proposed algorithm become the lower bounds to BER of concatenated convolutional codes with iterative decoding.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.1
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• pp.102-109
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• 2001

In this paper, in order to reduce the computational complexity of codebook, we propose a fast search algorithm which takes advantage of the information generated in the process of the self-organizing map (SOM). In an attempt to demonstrate the influence of the ordering of codebook on the performance of the partial distance search (PDS), we present the results of computation savings for three cases of ordering of codebooks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1B
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• pp.167-174
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• 2000

The three-step search(TSS) algorithm, a simple and gradual motion estimation algorithm, has been widely used in some low bit-rate video compression. We propose a new fast block motion estimation algorithm using the characteristics of motion in search region. Most of motion vectors exist in the center region of search area, so the notion in that region is examined more closely than TSS in this paper. Also in a search step, motion vector is estimated in the local area which is not overlapped with the search area in previous step, considering the all possible direction of motion. Therefore, we get the better motion estimation and reduce computational time in compared with the conventional methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.9C
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• pp.761-770
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• 2010

In this paper, we propose a new Frame Rate Up-Conversion (FRUC) scheme to increase the frame rate from a lower number into a higher one and enhance the decoded video quality at the decoder. The proposed algorithm utilizes the preliminary frames of forward and backward direction using bilateral prediction. In the process of the preliminary frames, an additional interpolation is performed for the occlusion area because if the calculated value of the block with reference frame if larger than the predetermine thresholdn the block is selected as the occlusion area. In order to interpolate the occlusion area, we perform re-search to obtain the osiomal block considerhe osiomnumber of available ne block consblock. The experimental results show that performance of the proposed algorithm has better PSNR and visual quality than the conventional methods.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.315-318
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• 2004

지금까지 대부분의 물류시스템은 생산자에서 최종 소비자에 이르는 생산물품의 수${\cdot}$배송에만 집중되어 왔으나, 최근 산업계에서는 기존의 수송시스템에 역방향 물류시스템을 통합하려는 시도가 이루어지고 있다. 본 논문에서는 배달화물과 수거화물이 혼합 적재되는 차량경로문제를 제안하고 이를 해결하기 위한 방안으로 유전알고리듬을 적용한 해법을 제시한다. 배달과 수거의 혼합적재를 허용함에 따라 고객지점에서는 적재된 혼합화물을 재배치하는 문제가 발생할 수 있다. 이 때 소요되는 적재화물의 재배치시간은 직관적인 수식으로 표현하였다. 유전알고리듬 개발과정에서 여러 가지 교차 연산자와 돌연변이 연산자들을 새롭게 고안하였다. 제안된 유전알고리듬 해법의 성능평가를 위하여 유사한 차량경로문제를 다루는 최신 알고리듬과 비교 계산실험을 수행하였다. 다양한 문제를 구성하여 실험한 결과, 제안된 유전알고리듬해법의 효과성이 입증되었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11A
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• pp.1889-1896
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• 2001

This paper proposes the hierachically regularized motion estimation technique for the efficient and accurate motion estimation. To use hierachical technique increases the reliability of motion vectors. And the regularization of neighbor vectors decreases bit rate of motion vectors. Also, using fast motion estimation algorithm with a few candidate vectors, the processing time added by regularization can be decreased. In the result of the experiment, the fast motion estimation with hierachical regularization technique achieves less computations and decreases estimation and distribution of false vectors.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2A
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• pp.128-139
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• 2004

As the Internet usage grows, people want to access the Internet while they are moving. To satisfy this requirement economically, IEEE 802.11 Wireless LANs(WLANs) are rapidly deployed. In order to support mobility, WLANs must provide smooth handoff mechanism. Recent studies show, however, handoff delay of WLANs exceeds 300ms, most of which is due to slow scanning mechanism finding a new AP. With this handoff delay, current WLANs is not suitable to provide seamless realtime interactive services such as VoIP sevice. In this paper, we analyze the current handoff method of IEEE 802.11 and we propose a new handoff algorithm which can decrease time needed for searching a new AP and thus reduce overall handoff time. We show by simulation that the proposed algorithm has shorter handoff delay than current handoff method.