• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.247-249
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• 2008

배전계통은 수용가에 전력을 공급하는 설비로서 계통의 안정적인 운영을 위하여 배전계통의 신뢰도를 산정하는 것은 중요한 의미를 갖는다. 본 논문에서는 배전계통을 구성하는 설비와 수용가의 전력 공급 유무에 따른 신뢰도를 산정하였다. Fault Tree Analysis(FTA)는 시스템의 고장을 해석하는 방법으로 사용된다. 시스템의 고장을 발생시키는 사건원인을 분석하여 Fault Tree(FT: 고장목)를 작성하고, 시스템을 구성하는 설비들의 고장확률 계산을 통하여 전 시스템의 신뢰성을 산정할 수 있다. 본 연구에서는 Relex 7.7 프로그램을 사용하여 FTA를 수행하였다.

• Journal of Digital Convergence
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• v.10 no.3
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• pp.51-58
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• 2012

The goal of this paper is to set up the rank list of the critical success factors according to its weights. To get the empirical data for this research, the Internet-based questionnaires were performed. This research is carried out in two steps. At first step, the critical success factors(CSF) are crystallized through factor analysis methods. To find out the weights and ranks of critical success factors in second step, the analytical hierarchical process(AHP) method were performed. The order list of all CSFs will be determined according to their priorities. This order list shows which factors have the most useful influence on the performance and success of SCM. This result could play the role as milestone for the effective management of Supply Chain Management System in korean manufacturing company.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.2
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• pp.123-131
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• 2009

The telecommunication technology in the 21st century has come up to the standard which could transmit various spatial information by means of on-line and the printing technology using computers has been on a par with presswork in quality. In addition, map users also would like to get various spatial information through on-line directly or indirectly. None the less, the supply system of national base map in our country has maintained the off-line sales method. It is owing to this reason that the nation's supply system has shown a high degree of inefficiency from the viewpoint of the inventory control, rapidity, and economical efficiency as compared with the on-line sales system in the developed countries. This study tried to analyze some problems of the present supply system in order to build up the foundation of the efficient map supply system and also developed the system such as On-demand maps, on-line paying and sales, inventory control, meta dat establishment, and security module, etc. This study tried to analyze some problems of the present supply system in order to build up the foundation of the efficient map supply system and also developed the system such as On-demand maps, on-line paying and sales, inventory control, meta dat establishment, and security module, etc.

• Journal of Korea Water Resources Association
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• v.32 no.2
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• pp.143-152
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• 1999

South-eastern part of Kyungbuk Province is suffering from lack of suitable water development sources due to geographic condition and insufficient water sources condition. In order to find an appropriate solution, extensive studies are carried out such as investigation of new dam sites, regional water supply system, modification of existing water supply system, rehabilitation of old water resources structures and development of off-stream reservoirs. The network optimization model is applied for evaluation of the newly suggested water development alternatives. The results show that if water supply system is constructed until 2011, the reliability of water supply to Pohang and Kyungju region will be more than 95% and the network optimization model can be used to analyse the management of water resources system considering water rights or priority orders.

• Journal of Bio-Environment Control
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• v.13 no.3
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• pp.125-129
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• 2004

This study was conducted to identify the growth characteristics of melon cultivated with mixture medium of scoria and perlite in capillary system. The growth and fruit characteristics of all cultivars cultivated under the nutrient solution capillary supplying system were comprehensively favorable. Fresh fruit weight of the three cultivars was similar to weight criterion (1.8 - 2.0 kg/fruit) of melon. In melon of non-net type ‘Aris’ there were no differences in fruit characteristics between nutrient solution supply methods, but total soluble solid (TSS) was higher in drip and capillary systems showing $15.6^{\circ}$Brix and 15.5$^{\circ}$Brix, respectively, than that of mist spray system showing $14.4^{\circ}$Brix. In melon of net type, ‘Earl's elite’, drip and capillary systems showed better fruit characteristics and higher values of TSS compared to mist spray system. The change in pH in the medium before and after melon cropping was not significant between systems, but the pH of upper layer within medium in all system was higher than that of lower layer. The mineral content within lower layer showed higher value than that of the upper layer in drip system, but reversed in capillary system.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.168-175
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• 2005

The pressurization system in a liquid rocket propulsion system provides a controlled gas pressure in the ullage space of the vehicle propellant tanks. It is advantage to employ a hot gas heat exchanger in the pressurization system to increase the specific volume of the pressurant and thereby reduce over-all system weight. A significant improvement in pressurization-system performance can be achieved, particularly in a cryogenic system, where the gas supply is stored inside the cryogenic propellant tank. The temperature characteristic of cryogenic pressurant is very important to develop some components in pressurization system. Numerical modeling and Test data were studied using SINDA/FLUINT Program and PTF(Propellant-feeding Test Facility).

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.3
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• pp.66-73
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• 2005

The pressurization system in a liquid rocket propulsion system provides a controlled gas pressure in the ullage space of the vehicle propellant tanks. It is advantage to employ a hot gas heat exchanger in the pressurization system to increase the specific volume of the pressurant and thereby reduce over-all system weight. A significant improvement in pressurization-system performance can be achieved, particularly in a cryogenic system, where the gas supply is stored inside the cryogenic propellant tank. In this study liquid nitrogen was used instead of liquid oxygen as a simulant. The temperature characteristic of cryogenic pressurant is very important to develop some components in pressurization system. Numerical modeling and test data were studied using SINDA/FLUINT Program and PTF(Propellant-feeding Test facility).

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.276-281
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• 2009

장거리 용수공급 시스템에서 전력비용은 전체 운영비용의 큰 부분을 차지한다. 본 연구는 시간단위의 펌프와 배수지 시스템의 최적 운영계획을 수립하기 위해 동적계획기법에 기초한 방법론을 제시하고 있다. 해석방법은 가용 가능한 펌프의 효율적 운전과 전력요금체계, 시간대별 용수수요추이 그리고 배수지 특성과 송수관로의 제약조건 등을 고려하였다. 이를 위해 적용 가능한 시스템 운영목적과 제약조건이 제시되었고 개발된 방법은 수도권 광역상수도 양주계통의 2개 가압장과 5개 배수지를 대상으로 적용되었으며, 적용결과는 상당한 수준의 펌프운전비용을 절감할 수 있는 것으로 나타났다. 이와 같은 방법은 생애주기 비용 최소화 측면에서 실제 용수공급 시설 운영과 대규모 용수공급 체계의 설계 등에 적용이 가능하다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.135-136
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• 2011

발전된 전력을 부하설비까지 공급하는 수송체계를 송배전 전력망이라 한다. 송배전전력망은 송배전 설비와 공급선로로 구성되어 있으며 각각 스카다와 배전자동화시스템에 의해 감시, 운영되고 고장발생 시 복구기능을 수행하고 있다. 경제성장에 따라 전력망은 계속 증가되고 운영방법도 더욱 복잡해져 자동화시스템만으로 설비의 상태진단과 고장예측은 물론 효율적 운영에 한계가 나타나고 있다. 또한 지구온난화의 해소를 위해 이산화탄소 감축에 필요한 신재생발전과 전기자동차 충전장치의 설치요구도 증가하고, 대용량 전력저장장치를 이용한 전력계통과 연계도 늘어나고 있다. 따라서 송배전설비와 정보통신기술의 융합을 통해 고장을 예방하고 전력계통운영의 효율화와 고품질의 전력을 안정적으로 공급하기 위한 스마트그리드 기반의 송배전전력망 통합운영시스템의 구성과 동작 체계를 제시하고자 한다.

• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.277-279
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• 2009

Hybrid 급전시스템은 신재생에너지와 상용전원에서 전원을 공급받아 사용자에게 DC 및 AC 전력을 공급해주는 시스템으로 상용전원의 효율을 향상시키고 신재생에너지의 사용 편의성을 올리며 가정에 AC와 DC를 동시에 공급하는데 주목적이 있다. 본 논문을 통해 DC 및 AC 동시 배전을 위해 가정용 부하의 특성을 분석하고 시스템의 동작특성을 해석한다.