• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.5B
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• pp.326-333
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• 2008

In wireless sensor networks, a sensor node with in-network aggregation adjusts the timeout which is a waiting time to receive messages from child nodes. This paper proposes a novel timeout scheduling scheme for data aggregation in wireless sensor networks, which adaptively configures its timeout according to changing data patterns in order to improve energy efficiency and data accuracy during data aggregation. The proposed scheme decreases the timeout when the temporal difference of collected data(data variation) from children is lower than a pre-defined threshold because there is no occurrence of critical events. Conversely, it increases the timeout when the data variation is higher than the pre-defined threshold in order to fulfill more accurate data aggregation. Extensive simulation reveals that the proposed scheme outperforms the cascading-based scheme in terms of energy consumption and data accuracy.

• Journal of Broadcast Engineering
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• v.4 no.1
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• pp.44-58
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• 1999

In this paper, a rate-distortion based image segmentation algorithm is presented using a recursive merging with region adjacency graph (RAG). In the method, the dissimilarity between a pair of adjacent regions is represented as a Lagrangian cost function considered in rate-distortion sense. Lagrangian multiplier is estimated in each merging step, a pair of adjacent regions whose cost is minimal is searched and then the pair of regions are merged into a new region. The merging step is recursively performed until some termination criterion is reached. The proposed method thus is suitable for region-based coding or segmented-based coding. Experiment results for 256x256 Lena show that segmented-based coding using the proposed method yields PSNR improvement of about 2.5 - 3.5 dB. 0.8 -1.0 dB. 0.3 -0.6 dB over mean-difference-based method. distortion-based method, and JPEG, respectively.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.5
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• pp.610-616
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• 2012

In this paper, we present a method to detect an object such as ship, rock and buoy from sea IR image for the safety navigation. To this end, we do the image smoothing first and the apply watershed algorithm to segment image into subregions. Since watershed algorithm almost always produces over-segmented regions, it requires posterior merging process to get meaningful segmented regions. We propose an efficient merger algorithm that requires only two times of direct access to the pixels regardless of the number of regions. Also by analyzing IR image obtained from sea environments, we could find out that most horizontal edge come out from object regions. For the given input IR image we extract horizontal edge and eliminate isolated edges produced from background and noises by adopting morphological operator. Among the segmented regions, the regions that have horizontal edges are extracted as final results. Experimental results show the adequacy of the proposed method.

• Proceedings of the Korea Contents Association Conference
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• 2012.05a
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• pp.13-14
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• 2012

최근 스마트 모바일 기기의 보급이 확산되면서 기존 유선 P2P기반의 서비스를 확장하여 무선 환경에서 이동 단말기를 대상으로 하는 모바일 P2P에 대한 서비스에 대한 연구가 진행되고 있다. 본 논문에서는 이동 P2P 환경에서 스카이라인 질의 처리를 효율적으로 수행하기 위해 로컬 스카이라인 병합을 이용한 효율적인 질의 처리 기법을 제안한다. 제안하는 기법은 동적인 속성을 고려한 스카이라인 질의 처리를 위해 질의 피어를 중심으로 로컬 스카이라인을 생성한 후 배포함으로써 불필요한 피어에 대한 가지치기를 수행한다. 모든 피어들에 대한 스카이라인 집합을 병합하여 전체 영역에 대한 글로벌 스카이라인을 형성할 수 있다. 이와 같은 특성을 통해 제안하는 기법은 스카이라인 질의 처리 성능을 크게 향상시킨다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.811-814
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• 2007

맵 합병 알고리즘은 최근에 활발히 연구되고 있는 위치 추정 알고리즘의 한 유형이다. 본 논문에서는 두 개의 인접한 지역 맵을 합병하는 새로운 기법을 제안한다. 이 기법은 기존의 기법에 비해서 보다 많은 거리 정보를 활용함으로써 보다 정확한 맵 합병을 가능하게 한다. 우리가 제안한 합병 기법에 기초한 앵커프리 위치 추정 알고리즘을 제시하고 모의실험을 통하여 기존의 기법에 비하여 성능의 향상을 달성함을 입증하였다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.04a
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• pp.157-160
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• 2007

본 논문에서는 입력 영상의 에지를 단일 세그먼트로 구성하고 같은 타원에 속하는 에지 세그먼트를 병합하여 타원검출의 속도와 정확도를 향상시키는 방법을 제안한다. 먼저 분기점은 이용한 라벨링 기법과 코너 패턴 정합 기법으로 연속된 화소들의 집합인 에지 세그먼트를 만든다. 구성된 에지 세그먼트와 Randomized Hough Transform에 의해 타원을 추정하여 병합하고 타원을 결정한다. 위 과정으로부터 얻어진 병합된 에지 세그먼트 집합 하나가 타원 하나를 구성하므로 입력 영상 내의 전체 타원의 개수를 정확하게 추정할 수 있다. 또한 전체 에지 화소들로 타원을 검출하는 기존 방법과 달리 분리된 에지 세그먼트 단위로 타원 변수를 결정하기 때문에 전체 수행시간을 크게 줄일 수 있다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1C
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• pp.45-51
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• 2010

In urban area, design and construction of civil engineering structures such as subway tunnel, underground space and deep excavation is impeded by unreliable site investigation. Variety of embedded objects, electric noises and traffic vibrations degrades the quality of site investigation, whatever the site-investigation technique would be. In this research, a preliminary research was performed to develop a dedicated site investigation technique for urban geotechnical sites, which can overcome the limitations of urban sites. HiRAS (Hybrid Integration of Surface Waves and Resistivity) technique which is the first outcome of the preliminary research was proposed in this paper. The technique combines surface wave as well as electrical resistivity. CapSASW method for surface-wave technique and PDC-R technique for electrical resistivity survey were incorporated to develop HiRAS technique. CapSASW method is a good method for evaluating material stiffness and PDC-R technique is a reliable method for determination of underground stratification even in a site with electrical noise. For the inversion analysis of HiRAS techniuqe, a site-specific relationship between stress-wave velocity and resistivity was employed. As for outgrowth of this research, the 2-D distribution of Poisson's ratio could be also determined.

• Journal of the Korea Computer Graphics Society
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• v.11 no.4
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• pp.21-27
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• 2005

본 논문에서는 연속된 모션 프레임의 효과적인 단순화를 매우 효율적으로 수행시킬 수 있는 점진적 모션 (progressive motion) 기법을 제안하고 실험 결과를 설명한다. 제안된 점진적 모션 기법에서는 효과적인 단순화를 위하여 인접한 두 모션간의 차이를 측정하는 수식을 정의하고 모션 LOD (level of detail)를 효율적으로 처리하기 위하여 모션 차이가 최소인 두 모션을 차례대로 병합하고 역으로 병합된 모션을 분해하는 기법을 사용하였다. 이 방법은 모션 편집 등에서 매우 빠른 속도로 모션 LOD를 제공하며 임의의 캐릭터의 실시간 시뮬레이션에서 효과적인 단순화 기법으로 적용될 수 있는 잠재력을 가지고 있다.

• The KIPS Transactions:PartD
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• v.16D no.4
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• pp.497-506
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• 2009

The method of effectively merging XML documents becomes necessary, as the use of XML is popular and the collaborative editing is required in the areas such as office documents and scientific documents editing works. As a solution to this problem, in this paper we present a theoretical framework for merging individual editing works by muli-users to a same source document. Different from existing approaches which merge documents themselves when they are merged, we represent editing works with a series of edit operations applied to a source document, which is called a edit script, merge those edit scripts by multi-users, and apply the merged one to the source document so that we can achieve the same effect of merging documents. In order to do this, assuming edit scripts based on insertion and deletion edit operations, we define notions such as static edit scripts, the intervention between edit scripts and the conflict between the ones, then propose the conflict conditions between edit scripts and the method of adjusting edit scripts when merged. This approach is effective in reducing network overhead in distributed environments and also in version management systems because of preserving the semantics of individual editing works.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.6
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• pp.2815-2822
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• 2011

Clustering method in wireless sensor networks is the technique that forms the cluster to aggregate the data and transmit them at the same time that they can use the energy efficiently. In this paper, I propose the hierarchical unequal clustering method using cluster group model. This divides the entire network into two layers. The data aggregated from layer 2 consisted of cluster group is sent to layer 1, after re-aggregation the total data is sent to base station. This method decreases whole energy consumption by using cluster group model with multi-hop communication architecture. Hot spot problem can be solved by establishing unequal cluster. I also show that proposed hierarchical unequal clustering method is better than previous clustering method at the point of network energy efficiency.