• Transactions of the Korean hydrogen and new energy society
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• v.20 no.3
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• pp.208-215
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• 2009

PEMFC stack power output is needed to be around 100 kW to meet the requirements of automotive application and scaling-up the active area of the stack cells will allow a higher power. In the case of scaling-up the active area of cells, it is difficult to obtain uniform in-plane internal conditions such as temperature, relative humidity and stoichiometry of the feed gas. These ununiformity with the location in the cell would affect both the performance and durability of the stack, so it is important to understand phenomena in the cell for improving them. In this study, the current density, electrochemical resistance and performance distribution measurement was performed to understand the ununiformity in a single cell using in-situ method; (1) Current Density Distribution (CDD) Device and (2) Segmented Cell Fixture. The influence of location of feed gas on the performance of a single cell was experimentally measured and discussed by using a segmented single cell which was composed of 8 compartments. The correlation between the location and performance in a single cell was discussed by these two tools and it was extended between the local characterization and the durability in a MEA by comparing the used cell with a fresh one. It was also studied in terms of electrochemistry by Electrochemical Impedance Spectroscopy.

• Korean Journal of Construction Engineering and Management
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• v.12 no.2
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• pp.12-20
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• 2011

Recently, construction site scale has been growing larger along with the growth of national economy. As construction market requires time reduction, cost saving, and improving quality, a cutting-edge technology applied research has been gradually studied for more efficient project management. In particular, the Real Time Location System (RTLS) technology, a real-time location tracking system of construction resources, can be effectively used in safety management. This technology has been studied and applied in various industries including architectural, marine, urban, and other industries. However, although tunnel construction in civil engineering has a narrow space and many safety risks, there are not researched about this content. Therefore, this study proposes an advanced safety management model for tunnel construction using the RTLS technology and a measurement method of the feasibility of this model in the construction site.

• Transportation Technology and Policy
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• v.13 no.3
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• pp.14-27
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• 2016

• Ecology and Resilient Infrastructure
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• v.9 no.3
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• pp.131-140
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• 2022

The magnitude and frequency of extreme floods are increasing owing to the effects of climate change. Therefore, multipurpose flood management techniques incorporating nature-based solutions have been introduced to mitigate the limitations of flood management and river design methods relying on existing observation data. Nature-based solutions to prepare for such extreme flooding events include ways to retreat the embankment, expand the floodplain, and reduce flood damage. To apply these technologies, adopting appropriate location selection methods based on various evaluation factors, such as flood damage reduction effects, sustainable ecological environments, river connectivity, and physical channel structure enhancements, should be prioritized. Therefore, in this study, the optimal location for implementing the multipurpose floodplain construction project was determined by selecting the location of the floodplain expansion with objectivity in the river waterfront area upstream of Daecheong Dam to downstream of Yongdam Dam. Through the final location determination, the Dongdaeje and Jeogokje sections were included in the optimal location considering both flood damage reduction and water environment improvement.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2002.04a
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• pp.119-127
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• 2002

위치기반서비스(LBS: Location Based Service)는 점차 확대되어 가는 무선정보통신 환경을 통해서 지리정보와 특정목적의 컨텐츠를 결합, 제공하는 서비스이다. 이 글에서는 현재 국내에서 상용화되어 있는 서비스 사례와 함께 위치기반서비스의 기본적인 구성과 무선측위기술, 그리고 최근 기술동향을 정리하였고 기술발전과 함께 진행되고 있는 국내, 국제표준화기구의 표준화방안과 무선측위기술의 위치정확도 향상방안을 제시하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2010.11a
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• pp.56-57
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• 2010

• Journal of the Korean Operations Research and Management Science Society
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• v.13 no.2
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• pp.25-33
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• 1988

An efficient heuristic solution procedure is developed for the minimum location problems. The gradient direction method and modified gradient approach are developed due to the differentiability of the objective functions. Suboptimal step size is obtained analytically. A Modified Gradient Procedure (NGP) is presented and compared with the hyperboloid approximation procedure (HAP) which is one of the best known methods.

• Communications for Statistical Applications and Methods
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• v.10 no.3
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• pp.1017-1024
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• 2003

An estimation problem of treatment effect for bivariate censored survival data is considered under location shift model between two sample. The proposed estimator is very intuitive and can be obtained in a closed form. Asymptotic results of the proposed estimator are discussed and simulation studies are performed to show the strength of the proposed estimator.

• Electronics and Telecommunications Trends
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• v.17 no.5 s.77
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• pp.129-137
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• 2002

최근 모바일 핸드셋을 포함한 모바일 서비스의 보급률이 향상되고, 소비자들의 다양한 요구를 충족시키기 위한 모바일 데이터 서비스들이 우리의 생활전반에 급격히 확산되고 있다. 그 중에서도 MLS(Mobile Location Services)에 대한 미국 정부차원의 의무화 규정과 상업적인 목적에서의 핸드셋 제조업체 및 이동통신 서비스 사업자들의 관심이 고조되고 있으며, 향후 MLS 시장 규모가 급성장할 것으로 전망되고 있다. 이에 본 고에서는 미국의 MLS 관련 기술과 시장 동향을 살펴보기로 한다.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.767-770
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• 1999

This paper investigates the performance of the hyperbolic position location(PL) technique in CDMA system. Hyperbolic PL systems are such technology that can provide accurate PL information using the existing cellualr/PCS infrastructure and without requiring additional hardware/software implementation within the mobile unit. The channel simulation is obtained by applying AWGN and multipath fading. The effect of the mobile position within the cell and the number of base stations on the accuracy of the hyperbolic PL technique is investigated.