• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1413-1416
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• 2005

본 연구에서는 인접하는 유역과 어떠한 동적인 상호작용없이 유출이 독립적으로 결정되는 자연방류형 단일저류지를 대상으로 기존의 연구에서 임계지속기간 결정에 빈번히 이용되었던 최대첨두유량 발생시간, 최대저류용량 발생시간, 최대 저류비 발생시간을 기준으로 한 임계지속기간을 산정하여 분석하므로써 자연방류형 단일저류지의 임계지속기간의 결정에 있어 합리적인 성과를 도출하고자 하였다. 적용결과, 최대 저류용량을 기준으로 한 경우에는 저류지 규모와 같은 제약조건을 가져오게 되고, 최대 저류비를 기준으로 한 경우에는 강우지속기간에 따라 저류비는 지속적으로 감소하므로 두 기준을 통하여 임계지속기간을 결정하는 것은 적합하지 않은 것으로 판단되었다. 따라서 허용방류량 고정개념을 통하여 최대 저류비, 최대 저류용량을 통하여 임계지속기간을 산정하였다. 그 결과 자연방류형 단일 저류지에서는 최대 저류용량을 통하여 적정 임계지속기간을 검토할 수 없는 것으로 판단되었다. 그러므로 최대 저류비를 이용하여 자연방류형 저류지에서의 최대 저류비를 발생시키는 시간분포를 정리한 결과 전체적으로 Huff 2분위가 최대 저류비를 발생시키는 것으로 나타났다. 그리고 첨두저류비 변화율을 검토한 결과 매우 제한적인 조건이기는 하지만 허용방류량 고정개념을 이용한 경우에 한하여 지속기간별 최대 첨두유량의 임계지속기간과 자연방류형 단일저류지의 임계지속 기간을 동일하게 간주하는 것이 큰 무리는 아닌 것으로 판단되었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3A
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• pp.140-150
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• 2003

In this paper, we propose a novel code sharing method for downlink transmission of mobile satellite communication systems using a multibeam geosynchronous-orbit satellite. In the proposed system, spreading codes are shared among downlink beams in order to increase the system capacity. We also propose efficient radio resource and transmit power allocation schemes for the proposed system. Simplified analysis and simulation results on the system capacity show the capacity improvement by the proposed scheme. The simulation results show that the capacity of the proposed system is more than 2 times as large as that of a conventional multibeam satellite system. In the frequency-selective fading channel, the capacity improvement increases as the interference between orthogonal spreading codes decrease.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.3A
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• pp.259-266
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• 2011

Femtocells are expected as the surest way to increase the system capacity with higher-quality links and more spatial reuse in future networks. In spite of their great potential, the system capacity is highly susceptible to network density because a large portion of users are exposed to inter-cell interference (ICI). In this work, we proposed a dynamic interference avoidance scheme in densely deployed cell environments. Our proposed DDIA (Distributed Dynamic ICI Avoidance) scheme not only works in a fully distributed manner, but also controls interference link connectivity of users with high agility so that it is suited for self-organizing networks (SONs). We introduced the concept of ICI-link and two-tier scheduling in designing the DDIA scheme. To avoid ICI without any central entity, our scheme tries to harmonize all base stations (BSs) with users adaptively. Through extensive simulations, it was shown that our proposed scheme improves the throughput of users by more than twice on average compared to the frequency reuse factor 1 scheme, who are exposed to ICI while maintaining or even improving overall network performance. Our scheme operates well regardless of network density and topology.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.2
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• pp.211-222
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• 1999

본 논문은 위성간 링크를 이용하여 저궤도 위성망을 구성할 때 발생하는 링크할당 문제를 효율적으로 풀기 위한 기법을 제안한다. 제안된 기법은 먼저 위성 궤도운동의 주기성에 기반하여 저궤도 위성망을 유한상태기계로 모델링한 후에, 유한상태기계의 각 상태에서 최적의 링크할당을 구하기 위해서 조합형 최적화 문제에 많이 쓰이는 시뮬레이팅드 어닐리을 이용한다. 제안된 기법의 이점은 저궤도 위성망을 유한상태기계로 모델링함으로써 도적인 움직임을 보이는 저궤도 위성망에서의 링크할당 문제를 고정된 위상을 가지는 망에서의 링크할당 문제로 단순화시키고 이를 토대로 최적화기법을 적용할 수 있다는 것이다. 시뮬레이티드 어닐링에 의하여 최적화된 링크할당의 성능은 정규링크할당과의 비교.분석을 통해서 평가된다. 최적화된 링크할당과 정규링크할당의 성능분석을 위하여 정적경로배정과 동적경로배정 기법이 고려된다. 시뮬레이션을 통한 실험결과는 정적경로배정을 적용한 최적링크할당 기법이 호 봉쇄확률 측면에서 최고의 성능을 가짐을 보여준다. 링크할당기법이 같은 경우에는 정적경로배정이 동적경로배정보다 우수한 성능을 보이는데 이는 동적경로배정의 경우에 상태전이 후에 경로배정 표가 안정화되기 위해서 많은 시간을 필요로 하기 때문이다. 본 논문에서는 제안된 링크할당 기법은 작은 용량의 위성간 링크를 가지고서 많은 호에대한 서비스를 제공하고자 할 때 유용하며, 호의 서비스를 위하여 실제로 필요한 위성간 링크의 용량은 실험결과로부터 유추될 수 있다.

• Journal of Korean Society of Transportation
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• v.23 no.5 s.83
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• pp.169-176
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• 2005

This paper introduces the dynamic control of acceleration lanes at freeway-ramp junctions. The feasibility of operation with flexible length of acceleration lane was tested with most possible traffic conditions. The operational qualify was also evaluated using average speed and total thru-put at both ramp section and freeway section. A CORSIM microscopic simulation model was used to evaluate the operation quality with a variety or volume conditions and three acceleration lanes, each representing different length categories. In addition, tollgate O-D data including travel times were obtained for two sections on the Gyeong-bu Freeway where an effective merging distance has been largely reduced. Its effect was analyzed and compared to the simulation results. Finally, the effects of acceleration lane are discussed and operational improvement at junctions is presented as research findings.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.5
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• pp.560-566
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• 2003

Recently, many researches on RC(Reconfigurable Computing) with highly complex FPGA's and reconfigurable processors have been reported, and even some attempts for commercialization have been successful. In this paper, we introduce the design methodology for implementing DES crypto algorithm on small-capacity FPGA by using its dynamic reconfigurability and a system-level verification technique. Throughout this design project, we could evaluate the effectiveness of this approach, which is the dynamic reconfigurability of FPGAs makes the efficient trade-off between the performance and the cost robustly viable.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.2
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• pp.125-134
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• 2004

The new deregulated economic environment in the power utility market is forcing fundamental changes in the investment and operational decisions regarding transmission lines. Hence, it has come to be an important issue to evaluate their current utility in order to increase conductor ampacity based on conservative assumptions of worst case weather conditions. Static thermal rating has born still applied in most power companies worldwide, however some of them have been done various trials such as monitoring dynamic line ratings to increase line ratings in real time. This study is an attempt to access the static line ratings in Korea Electric Power Corporation(KEPCO) transmission lines, which were specified by weather model. Several environmental performances for determining static line ratings are examined by using the past weather data of Korean Meteorological Administration. As a result, it is shown that seasonal or regional line ratings could be adopt to the KEPCO's transmission lines, and their line ratings could be more increased without refurbishing current conductors in service to new high-temperature ones.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.11
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• pp.1463-1469
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• 2020

Multimedia information, including video and voice, is highly utilized in that it is easily understood by people. For this reason, applications have been studied which store multimedia information in IoT devices and transmit information in conjunction with smartphones. The problem is that the size of information can be larger than the capacity of IoT devices due to video and image. In this paper, the multimedia content design technique, which takes into account the limitations of storage capacity, was studied when there is a limit of storage capacity. Considering that the video has a higher understanding of information than text, while the capacity is larger, the solution between information comprehension and capacity is sought. The size of static and dynamic media is a variable and the harm is solved in accordance with the linear planning method. Case studies have shown that the design techniques of this paper are useful.

• Journal of Korean Society of Transportation
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• v.25 no.2 s.95
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• pp.73-81
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• 2007

The purpose of this paper is to perform a basic study on the interaction between lanes, which can be achieved through analyzing traffic breakdown at the microscopic level. Using aerial photographic data for the microscopic analysis, this study analyzed the characteristics of traffic flow at a merging area. This research produced aggregated traffic data such as flows, speeds, and densities in 30 second intervals by lane for the macroscopic analysis and individual headway data by lane for the microscopic analysis. The paper contains an analysis of lane characteristics through flows, speeds, densities, and headway variations and also investigates the influence of ramp flows on mainline flows with space-time diagrams. Firstly, the merging area in this study is divided into three sections: before-merging, during-merging, and after-merging. The transition process was analyzed at each lane. Secondly, the breakdown was observed in detail with data divided in 50-foot units. The breakdown was checked through the relationships between ramp and freeway mainline flows, various techniques were proposed to analyze the breakdown, and the formation of breakdown was introduced as three stages in this study. In the near future, the findings of this study could contribute to determining the dynamic capacity on freeways by easily understanding changeable traffic breakdown patterns over time and space.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.391_392
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• 2009

DTS 시스템에서 측정하는 분포온도 데이터는 지중케이블의 상태 감시에 유용하게 사용될 수 있다. 본 연구에서는 분포온도센서로부터 획득되는 온도 데이터를 기반으로 지중케이블의 상태 감시 및 실시간 허용용량을 산정할 수 있는 모니터링 시스템을 개발하였다. 본 시스템은 사례 기반의 모니터링 GUI를 구축하는 것을 지양하고, 임의의 지중케이블 시스템에 적용이 가능한 GUI 설정 기능을 갖추었으며, 케이블의 동적허용용량 산정 모듈, 분포온도 해석 모듈, 경보 모듈, 설정 모듈, 이력조회 모듈 등으로 구성된다.