• Journal of the Korea Society for Simulation
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• v.19 no.4
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• pp.129-137
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• 2010

Currently used shortest path search algorithms involve graphs with vertices and weighted edges between each vertex. However, when finding the shortest path with a randomly shaped obstacle(an island, for instance) positioned in between the starting point and the destination, using such algorithms involves high memory inefficiency and is significantly time consuming - all positions in the map should be considered as vertices and every line connecting any of the two adjacent vertices should be considered an edge. Therefore, we propose a new method for finding the shortest path in such conditions without using weighted graphs. This algorithm will allow finding the shortest obstacle bypass given only the positions of the obstacle boundary, the starting point and the destination. When the row and column size of the minimum boundary rectangle to include an obstacle is m and n, respectively, the proposed algorithm has the maximum time complexity, O(mn). This performance shows the proposed algorithm is very efficient comparing with the currently used algorithms.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.2
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• pp.68-74
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• 2005

In deadline scheduling, jobs have deadlines by which they are completed. The scheduling algorithm determines which jobs are executed at each time. Then only the completed jobs contribute to the throughput or gain of the algorithm. The jobs have arbitrary weights and the gain of the algorithm is given as the sum of weights of the completed jobs. The goal of the scheduling algorithm is to maximize its gain. In this paper, we consider online non-preemptive scheduling, where jobs arrive online and the scheduling algorithm has no information about jobs arriving ahead. Also the jobs cannot be preempted or rejected while they are executed. For this problem, we obtain lower bounds for any online algorithms and also we propose an optimal online algorithm meeting the lower bounds.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.2
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• pp.370-376
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• 2009

Recently, Study for routing protocol is gone vigorously in the Ubiquitous Sensor Network. A hierarchical routing protocol is being practical and received interest among them. Therefore we analyze a weak point of HEED. And I suggest the new protocol that solved a weak point of HEED. The new protocol that we propose puts weight in the energy remainder amount than HEED and elect CH. And elected CH is designed to change by new node when quantity of energy leftover becomes less than 50%. Therefore all nodes come to use energy fairly. The protocol that we proposed can prove the cluster survival rate about 30%. And CH is more effective because when elect CH replace, response time selects small node.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3C
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• pp.241-248
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• 2007

In predictive image coding, a LS (Least Squares)-based adaptive predictor is an efficient method to improve image edge predictions. This paper proposes a hybrid interpolation with weighted edge detector. A hybrid approach of switching between bilinear interpolation and EDI (Edge-Directed Interpolation) is proposed in order to reduce the overall computational complexity The objective and subjective quality is also similar to the bilinear interpolation and EDI. Experimental results demonstrate that this hybrid interpolation method that utilizes a weighted edge detector can achieve reduction in complexity with minimal degradation in the interpolation results.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2570-2572
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• 2005

본 논문에서는 다중 경로 오차 제거를 위해, 4개의 상관값을 제공하는 가중 협대역 상관기(Weighted Narrow Correlator) 구조에 대해 제안한다. 가중 협대역 상관기는 서로 다른 칩 간격을 가지는 여러 상관값 출력에 가중치를 주어 다중경로 신호에 의한 코드 위상 측정 오차를 줄이는 방법이다. 우선 다양한 지연시간 및 신호 감쇄를 가지는 다중 경로 신호에 대하여, 가중치에 대한 수신기의 성능 변화를 분석하고 이를 통해 최적의 가중치를 선택하였다. 제안한 상관기는 일반 수신기와 동일한 신호 획득능력을 가지며, 협대역 상관기보다 개선된 다중경로 오차 제거 능력을 보인다. 가중 협대역 상관기의 성능은 시뮬레이션을 통한 의사거리 측정치의 비교를 통해 검증하였다.

• The Journal of the Acoustical Society of Korea
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• v.22 no.2
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• pp.96-103
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• 2003

This paper describes a method for sinusoidal modeling of audio signals using perceptually weighted matching pursuit. Matching pursuits extracts iteratively the greatest energy signals from the input signals until the residual between the original and the reconstructed signal is zero. In this paper, perceptual matching pursuits using psychoacoustic model to matching pursuit extracts greatest perceived energy iteratively. To evaluate the performance of the perceptual matching pursuits it is compared with the sinusoidal matching pursuits which is not included perceptual weighting. For various audio signals the result of simulation shows that the perceptual matching pursuit is superior to the sinusoidal matching pursuits, especially for a high change rate in time domain it can synthesized original signal.

• Annual Conference on Human and Language Technology
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• 2001.10d
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• pp.171-174
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• 2001

현재, 전자메일을 정보전달의 수단이나 광고등의 목적으로 많이 이용하게 되면서, 메일 수신자는 원치 않는 상업적 광고, 불필요한 정보등의 스팸메일을 여과 없이 수신하게 되는 경우가 많아졌다. 이로 인하여 업무효율성 감퇴, 시간 낭비, 자원 낭비 등의 많은 문제점을 야기시키고 있다. 이러한 문제점을 해결하기 위한 기존의 메일 필터링 시스템들은 송신자의 주소나 도메인, 제목 등의 메일 헤더정보만을 이용하거나, 사용자가 정의한 문장이 본문 내용에 나타날 때 필터링하는 방식들이 주류를 이루고 있다. 그러나 이러한 방식들은 메일의 내용에 대한 근본적인 필터링이 불가능하다. 본 논문에서는 메일의 내용을 파악하기 위해 메일의 내용을 대표할 수 있는 체언정보를 추출하여, 카이제곱 통계량 공식을 통해 단어 가중치를 부여하고, 이를 문서분류를 위한 로그단어 빈도 가중치 공식에 적용하여 스팸메일을 필터링하는 방식을 제시한다. 본 논문에서 제안한 방법으로 실험한 결과, 스팸메일을 필터링하는데 84.61%의 재현율과 83.01%의 정확율을 얻을 수 있었다.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.10
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• pp.556-568
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• 2003

This paper presents and analyzes the performance of a weighted-window based cache replacement policy for the efficient media caching in streaming media cache servers. The proposed policy makes, for each cached object, use of the reference count, reference time, amount of media delivered to clients and, in particular, the periodic patterns of user requests. Also, by giving weights to the recently referenced media contents, the replacement policy adequately and swiftly reflects the ever-changing characteristics of users preferences. The simulation studies show that the performance of the proposed policy has improved over the conventional policies such as LRU, LFU and SEG - in terms of hit ratio, byte hit ratio, delayed start and cache input.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.07a
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• pp.429-432
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• 2020

본 논문에서는 카메라의 포커싱과 아웃포커싱에 의해 이미지에서 뿌옇게 표현되는 DoF(Depth of field, 피사계 심도) 영역을 합성곱 신경망을 통해 찾는 방법을 제안한다. 우리의 접근 방식은 RGB채널기반의 상호-상관 필터를 이용하여 DoF영역을 이미지로부터 효율적으로 분류하고, 합성곱 신경망 네트워크에 학습하기 위한 데이터를 구축하며, 이렇게 얻어진 데이터를 이용하여 이미지-DoF가중치 맵 데이터 쌍을 설정한다. 학습할 때 사용되는 데이터는 이미지와 상호-상관 필터 기반으로 추출된 DoF 가중치 맵을 이용하며, 네트워크 학습 단계에서 수렴률을 높이기 위해 스무딩을 과정을 한번 더 적용한 결과를 사용한다. 본 논문에서 제안하는 합성곱 신경망은 이미지로부터 포커싱과 아웃포커싱된 DoF영역을 자동으로 추출하는 과정을 학습시키기 위해 사용된다. 테스트 결과로 얻은 DoF 가중치 이미지는 입력 이미지에서 DoF영역을 빠른 시간 내에 찾아내며, 제안하는 방법은 DoF영역을 사용자의 ROI(Region of interest)로 활용하여 NPR렌더링, 객체 검출 등 다양한 곳에 활용이 가능하다.

• The KIPS Transactions:PartC
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• v.13C no.5 s.108
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• pp.559-566
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• 2006

Virus throttling technique, one of many early worm detection techniques, detects the Internet worm propagation by limiting the connect requests within a certain ratio. The typical virus throttling detects worm occurrence by monitoring the length of delay queue with the fixed period of rate limiter. In this paper, we propose an algorithm that controls the period of rate limiter autonomically by utilizing the weighted average delay queue length and suggest various period determination policies that use the weighted average delay queue length as an input parameter. Through deep experiments, it is verified that the proposed technique is able to lessen inconvenience of users by reducing the connection delay time with haying just little effect on worm detection time.