• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.307-310
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• 2002

최근 물부족 현상은 심각한 사회ㆍ환경적 문제가 되고 있으며, 이에 대처하기 위한 방안의 하나로 지표수-지하수 연계이용이 대두되고 있다. 지표수와 지하수 연계이용은 수자원을 수문학적 순환 사이클의 관점에서 파악하고 상호보완적 이용을 도모하는 통합적인 방안이다 본 연구는 계획 수립단계에서 연계이용의 가능성, 시급성 측면에서 최적의 대상지역을 선정하기 위한 체계적인 적지분석 방법론을 제시한다. 이를 위해 복잡한 의사결정 문제를 계층적으로 나누어 분석하는 기법(AHP)이 적용되었다. AHP를 통해 분석에 필요한 의사결정인자를 도출하였고, 그 상대적 중요도를 정량화 하였다. 입지인자의 중요도를 바탕으로 가상의 지역에 대한 각 측면의 적합도를 산정하였고, 비중을 달리함으로써 얻어지는 다양한 대안에 대하여 최종적인 적합도가 산정되었다. 이러한 방법론에 의거한 분석자료는 최종적인 의사결정을 위한 기초정보를 제공할 것이며, 지역 간 연계이용 우선순위를 평가하는데도 활용될 수 있을 것이다.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.1499-1502
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• 2005

본 논문에서는 차별화 서비스(Differentiated Service)를 구현하기 위하여 퍼지 이론을 적용한 웹 서버 컴퓨팅 노드들의 동적인 성능 분리(Performance Isolation) 기법에 관하여 논하였다. 제안된 기법은 컴퓨팅 노드의 현재 부하량, 사용자 계층별 요청률을 퍼지 입력 변수(Fuzzy Variables)로 하여, 애매모호한 노드의 정량적 부하를 정성적으로 표현할 수 있도록 하였으며, 이를 통해 계층별 요청률의 급격한 변화에 대응하여, 계층별 요청을 처리하는 담당 노드의 수를 동적으로 조절할 수 있게 하였다. 성능분석을 통해 제안된 퍼지 기반 성능 분리 방식의 서비스 응답시간이 퍼지기법을 사용하지 않은 일반적인 성능 분리에 비해 개선되는 것을 확인하였다.

• Journal of KIISE:Information Networking
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• v.31 no.6
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• pp.608-619
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• 2004

Application layer multicast(ALM) has been developed as an alternative to support the multi-receiver applications due to the slow deployment of IP multicast. Unlike routers in IP multicast, end systems participating in a ALM session are not optimized for relaying data and have various processing and network capacity. Therefore, with the increased role of end systems, the delay incurred at the end systems occupy large portion of the end-to-end delay. In this paper, we model the end system delay of ALM sessions and analyze its impact on the performance of the existing ALM schemes. Furthermore, we propose an enhanced scheme, based on the existing mesh-based scheme, which reflects the end system delay We also evaluate the performance of the proposed scheme by simulation and show that it reduces the end-to-end delay compared with the existing scheme.

• Journal of Korea Multimedia Society
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• v.9 no.1
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• pp.1-10
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• 2006

In document clustering methods, the k-means algorithm and the Hierarchical Alglomerative Clustering(HAC) are often used. The k-means algorithm has the advantage of a processing time and HAC has also the advantage of a precision of classification. But both methods have mutual drawbacks, a slow processing time and a low quality of classification for the k-means algorithm and the HAC, respectively. Also both methods have the serious problem which is to compute a document similarity whenever new document is inserted into a cluster. A main property of web resource is to accumulate an information by adding new documents frequently. Therefore, we propose a new method of transitive closure tree based on the HAC method which can improve a processing time for a document clustering, and also propose a superior incremental clustering method for an insertion of a new document and a deletion of a document contained in a cluster. The proposed method is compared with those existing algorithms on the basis of a pre챠sion, a recall, a F-Measure, and a processing time and we present the experimental results.

• Journal of the Korea Computer Industry Society
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• v.3 no.3
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• pp.391-406
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• 2002

In order to realize a practical VOD system, it is necessary for a high-capacity and cost-effective hierarchical VOD server based on tertiary storages such as DVD jukebox. In such a system, it is possible to transfer multiple streams to users by alternatively swapping DVDs using the fixed number of drives. But it takes a long time for loading DVD to a drive. In this paper, we propose a primitive pipelined loading mechanism for hiding the loading time to swap DVDs in a hierarchical VOD server based on DVD jukebox. We also propose a enhanced pipelined loading mechanism for increasing the maximum admittable streams with the fixed number of drives. The enhanced mechanism caches the initial segment of each stream on a disk storage allowing faster data transfer. The performance analysis shows that the proposed mechanisms can admit the maximum allowed stream capacity under the fixed number of disk drives.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.3 s.303
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• pp.31-40
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• 2005

In this paper, we develop an approach toward JSC(Joint Source-Channel Coding) method for MPEG-4 based FGS(Fine Granular Scalability) video coding and transmission in fixed and mobile receiving environment(Digital Audio Broadcasting, DAB). The source coder used MPEG-4 FGS video codec, the channel coder used RCPC(Rate Compatible Punctured Convolution) code and the modulation method used QPSK modulation. We have considered channel environment of AWGN and mobile receiving environment. This study determined optimum Trade-off point between source bit rate and channel coding rate in variable channel states. We compared FGS-JSC method and general single layer CBR(Constant Bit Rate) transmission. In this results, FGS-JSC was appeared better performance than CBR transmission.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.3
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• pp.117-126
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• 2009

Various dimensions of watershed structural/non-structural planning can be applied in comprehensive flood mitigation plan in a river basin. Especially structural counterplans have very broad and diverse nature as flood control facilities. It is not easy to find the optimum alternative to maximize the ability of a basin to reduce flood risk using a combination of structural counterplans. In addition, there is no standard for evaluating the performance of structural counterplans and for selecting optimal combination of them. This study focused on how to select the best alternative of a comprehensive watershed structural plan from various flood defense alternative candidates. By introducing an analytic hierarchy process, we would like to show how we decide the best alternative using standard worksheets developed in this study for economics and policy evaluation, and Expert Choice 11.5, which calculates weights for evaluation items. Based on the results from this study, we would like to suggest the best practice of a standardized watershed plan for flood protection.

• Journal of Korea Water Resources Association
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• v.54 no.9
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• pp.643-656
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• 2021

Recently, water supply management technology is highly developed, and a computer simulation model plays a critical role for estimating hydraulics and water quality in water distribution networks (WDNs). However, a simulation of complex large water networks is computationally intensive, especially for the water quality simulations, which require a short simulation time step and a long simulation time period. Thus, it is often prohibitive to analyze the water quality in real-scale water networks. In this study, in order to improve the computational efficiency of water quality simulations in complex water networks, a hierarchical water-quality-simulation technique was proposed. The water network is hierarchically divided into two sub-networks for improvement of computing efficiency while preserving water quality simulation accuracy. The proposed approach was applied to a large-scale real-life water network that is currently operating in South Korea, and demonstrated a spatiotemporal distribution of chlorine concentration under diverse chlorine injection scenarios.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.57-58
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• 2009

임베디드 시스템이 복잡해질수록, 성능 병목을 파악할 수 있는 성능 분석도구가 요구되고 있다. 현존하는 리눅스 기반의 소프트웨어 성능 분석 도구는 전체 시스템 관점에서 소프트웨어 계층에 따라 응용 소프트웨어의 실행 흐름을 파악하기에는 한계가 있다. 본 논문에서는 모든 소프트웨어 계층에서의 실행 흐름을 일관적으로 파악할 수 있는 문맥 분석 기법을 제안한다. 이 도구를 통해서 사용자 영역의 사용자 정의 함수와 라이브러리 함수, 커널 영역에서의 시스템 호출과 커널 이벤트에 대한 호출자와 피호출자에 대한 관계를 모두 파악할 수 있다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.3
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• pp.133-140
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• 2018

This paper is concerned with the 2-D micostructure generation for $Ni-A{\ell}_2O_3$ dual-phase composite materials and the numerical analysis of mechanical characteristic of hierarchical models of microstructure which are defined in terms of the scale of microstructure. The microstructures of dual-phase composite materials were generated by applying the mathematical RMDF(random morphology description functions) technique to a 2-D RVE of composite materials. And, the hierarchical models of microstructure were defined by the number of Gaussian points. Meanwhile, the volume fractions of metal and ceramic particles were set by adjusting the level of RMD functions. The microstructures which were generated by RMDF technique are definitely random even though the total number of Gaussian points is the same. The randomly generated microstructures were applied to a 2-D beam model, and the variation of normal and shear stresses to the scale of microstructure was numerically investigated. In addition, through the crack analyses, the influence of RMDF randomness and Gauss point number on the crack-tip stress is investigated.