• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.140-144
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• 1988

This paper describes requirements for cogenerating in parallel with utility. Cogenerating is the simultaneous generation of energy in two or more forms, usally electricity and heat. Cogeneration is most energy efficient when generating in paralled will the electric utility, but requires proper control and protection. When onsite generation and utility systems are operated in parallel, there are many factors. such as operation mode. point of connection, grounding, synchronizalion. protective relaying, metering, and the like, that must be considered to provide safe and efficient operation.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.343-346
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• 1996

A new method for on-line induction motor fault detection is presented in this paper. This system utilizes unsupervised-learning clustering algorithm, the Dignet, proposed by Thomopoulos etc., to learn the spectral characteristics of a good motor operating on-line. After a sufficient training period, the Dignet signals one-phase ground fault, or a potential failure condition when a new cluster is formed and persists for some time. Since a fault condition is found by comparison to a prior condition of the machine, on-line failure prediction is possible with this system without requiring information on the motor of load characteristics.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.201-203
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• 2011

The purpose of this study was to develop and evaluate of fire resistive cladding systems for HSC(high-strength concrete) column, which was mainly constructed with aerogel blanket insulation material. The aerogel blanket-fire protective gypsum board cladding system showed that it clearly secure the fire resistance performance of HSC column when the reinforcing measures had achieved for four cross-sectional edge sides of structure and the system is well continued during the test period with no significant deformation or separation etc. It was checked out the 20mm thickness cladding system consist with AG(5mm)+FGB(15mm) can secure 3hour-fire resistance performance adequately.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.6
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• pp.665-670
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• 1999

This paper introduces a fuzzy expert systems for fault diagnosis, where the causal relationships between faults and protective devices are defined as fuzzy relations. The uncertainties existing in the fault diagnosis are figured out using the possibility theory and the possibility measure is associated with the fuzzy relation to evaluate the possibilities of faults. Besides, the knowledge base in the expert system is described and explained. In this way, multiple-fault can be handled easily and simultaneously together with single faults.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.136-139
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• 2001

KEPRI successfully developed and installed RTDS(Real-Time Digital Simulator) during March 2001. The simulator will be used to study interactive simulation of electromagnetic & electromechanical and validation of protective & control systems. In this paper. the authors will present an overview of real-time digital simulator and its characteristic features. Special emphasis will be placed to the installation test results. This paper also addresses some key issues on the accuracy, reliability flexibility and its practical uses for real-time power simulation.

• Journal of the Korean Ceramic Society
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• v.45 no.10
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• pp.600-604
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• 2008

Although titanium-ceramic systems have gained substantial interests in dental prosthetic field, bonding problem between porcelain and titanium has not been solved. Main obstacle in titanium-porcelain bonding is excessive oxidation of titanium during porcelain firing. The effects of several coating materials on the bonding strength of titanium-porcelain system were investigated in this study. RF sputtering and electroplating of platinum significantly increased the bonding strength of porcelain-titanium specimen. However, coatings of Ni-Au, Ir, and ceramics(zirconia and hydroxyapatite) did not showed a significant effect on bonding strength. Platinum might be a promising material for the protective layer of excessive oxidation of titanium during porcelain firing, resulting in increase in the bonding strength.

• Korean Security Journal
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• no.1
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• pp.17-50
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• 1997

I study on the security organization for the chief of state in North and South Korea. The paper, purporting to analyze security system in comparative prospectives, comprise four chapters. Chapter I Which sets out purpose, scope and method, is followed by Chapter II , dealing largely with the power structure on The Socialist Constitution of Democratic People's Republic of Korea, the protection organization and security activities for the chief of state in North Korea. Chapter III concerns the security environment - terrorist groups, firearms, explosives, suspects, movements of hostile countries and orthers - and the protection organization on The Presidential Security Service for the president in South Korea, culminating in projection of certain problem area. It is followed by concluding observation made in Chapter IV. To be operated security systems effectively, these need to be regulated according to a protective scale, function, authority of a existing.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.190-192
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• 1997

In this paper we developed an object-based expert system for electric power system fault diagnosis. The object corresponds to a hardware or event in real world and they are independent each other. The expert system is designed to estimate the fault sections and identify the false operation, nonoperation of protective devices. The expert system was developed using C++ language in pentium PC. We applied the expert system in various sample systems and showed that making up a knowledge base is easier and diagnosis was done in a approximately real time.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1189-1190
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• 2015

최근 정부의 일련의 강력한 정책의 시행으로 계통에 분산형전원의 설치가 빠르게 증가하고 있다. 게다가 2015년 4월부터는 분산형전원의 저압계통 연계기준이 500kW 미만으로 크게 늘어 신재생에너지를 이용한 분산형전원의 계통 연계량의 증가는 더욱 늘어날 것으로 예상된다. 특히 저압계통에 연계되는 분산형전원의 연계용량이 늘어남에 따라 기존 연계 기준에서는 큰 영향을 미치지 않았던 고장들도 사고 발생 시 특고압으로 운영 중인 배전계통에 미치는 영향도 같이 늘어난다. 따라서 본 논문에서는 기존과는 달라진 환경에서 계통에서 발생할 수 있는 문제점을 분석하여 대책을 제시하도록 하겠다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.944-945
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• 2015

Many sensitive loads always rely on UPS systems to maintain continuous power during abnormal utility power conditions. As any disturbance occurs at the utility side, an off-line UPS system takes over the load within a quarter cycle to avoid a blackout. However, the starting of the inverter can root the momentous inrush current for the transformer installed before the load, due to its magnetic saturation. The consequences of this current can be a reduction of line voltage and tripping of protective devices of the UPS system. Furthermore, it can also damage the transformer and decrease its lifetime by increasing the mechanical stresses on its windings. To prevent the inrush current, and to avoid its disruptive effects, this paper proposes an off-line UPS system that eliminates the inrush current phenomenon while powering the transformer coupled loads, using a current regulated voltage source inverter (CRVSI) instead of a typical voltage source inverter (VSI). Simulations have been performed to validate the operation of proposed off-line UPS system.