• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1512-1518
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• 2009

Recently, new dispersed power sources such as photovoltaics, wind power, fuel cell etc. are energetically interconnected and operated in the distribution systems, as one of the national projects for alternative energy. This paper deals with the optimal countermeasures for the mal-function of protective devices at primary feeder in distribution systems when new power sources like photovoltaic (PV) systems are interconnected, based on the symmetrical components of short circuit studies. When new power sources are considered to be interconnected to distribution systems, bi-directional power flow and interconnection transformer connection of new power sources may cause the operation problems of protective devices (mainly re-closer), since new power sources can change typical characteristics of distribution systems. Therefore, this paper shows an analysis skill of the mal-functional mechanism of protective relay and proposes the optimal solution for the mal-function problem using the symmetrical components of fault analysis. And, this paper also shows the effectiveness of proposed method by the simulation at the field distribution systems.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.3
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• pp.91-98
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• 2003

The importance of improving the quality of electric power is being strongly raised, owing to an increasing use of sensitive and small-sized electronic devices and systems. The transient over-voltages on low-voltage power distribution systems are induced by direct or indirect lightning return strokes. These can cause damage and/or malfunction of the utility systems for home automation, office automation, factory automation, medical automation, etc. The behaviors of lightning overvoltages transferred through the transformer to the low-voltage distribution systems using a Marx generator were experimentally investigated. Furthermore, the coupling mechanisms of lightning overvoltages transferred to the low-voltage systems were clearly illustrated through a theoretical simulation using a Pspice program. The overvoltages in low-voltage ac power systems are rarely limited by the application of the surge arrester to the primary side of the distribution transformer. A superior surge protection scheme is to install surge protection devices at the service entrance switchboard and/or at the load devices in TN power systems.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.712-718
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• 2013

With the development of industry and the improvement of living standards, better quality in power electric service is required more than ever before. This paper deals with the optimal algorithms for voltage regulation in the case where Distributed Storage and Generation (DSG) systems are operated in distribution systems. It is very difficult to handle the interconnection issues for proper voltage managements, because the randomness of the load variations and the irregular operation of DSG should be considered. This paper proposes the optimal on-line real time voltage regulation methods in power distribution systems interconnected with the DSG systems. In order to deliver suitable voltage to as many customers as possible, the optimal sending voltage should be decided by the effective voltage regulation method by using artificial neural networks to consider the rapid load variation and random operation characteristics of DSG systems. The simulation results from a case study show that the proposed method can be a practical tool for the voltage regulation in distribution systems including many DSG systems.

• Journal of Korean Society on Water Environment
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• v.33 no.3
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• pp.359-369
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• 2017

Water distribution systems supply drinking water to consumers' taps. Internal corrosion of metallic pipe used in drinking water distribution systems has reduced water quality and led to increased levels of toxic heavy metals such as lead, copper and nickel. These problems have been experienced to varying degrees by water utilities in many countries. North America has successfully managed and controlled pipe corrosion and corrosive water in water distribution system based on various policies, regulations and rules. Practical and engineering guidelines for evaluation of pipe corrosion and determination of treatment options are also provided to assist drinking water supplies. In addition, the corrosion mechanism in water distribution systems, such as the complex effects of physical and chemical parameters on the corrosion pipes has been improved to accurately predict corrosion rates of metallic pipes in actual water distribution systems. This paper reviews various regulations, policy statement, and treatment produces on controlling corrosion in drinking water distribution systems in US and Canada and then offers suggestion for management of corrosive water and pipe corrosion in drinking water distribution system in Korea.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.3
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• pp.301-312
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• 1999

Experiments were carried out to evaluate performance of the cold air distribution systems with an ice storage tank in test room. Cold air distribution systems provide primary air for comfort conditioning or process cooling at coil discharge temperatures$4^{\circ}C$ to$11^{\circ}C$. The application of a cold air distribution system allows for the downsizing of air distribution equipment and central plant equipment when ice storage tank is used. The benefit of a cold air distribution system include a decrease in the floor-to-floor height, increase floor space, reduced building capital costs, reduced energy use and demand. The use of cold air distribution can result in the most cost effective system and is currently being implemented world wise as the new standard in air conditioning systems. In this study, the cold air distribution system is compared with the general ice storage system. Under the same cooling load conditions, experimental results show that the supply air volume of cold air distribution system decrease 38%, and decrease 45% flow rate of brine for the general ice storage system.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.2219-2220
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• 2006

This paper aims to analyze the overvoltage in underground distribution systems when lightning surge strikes to overhead line. The model is established by EMTP/ATPDraw for actual distribution systems. Simulation is carried out considering variation of parameters such as length and lightning current.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.587-588
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• 2006

This paper aims to analyze the overvoltage in underground distribution systems when lightning surge strikes to overhead line. The model is established by EMTP/ATPDraw for actual distribution systems. Simulation is carried out considering variation of parameters such as length and lightning current.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1253-1254
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• 2006

This paper aims to analyze the overvoltage in underground distribution systems when lightning surge strikes to overhead line. The model is established by EMTP/ATPDraw for actual distribution systems. Simulation is carried out considering variation of parameters such as length and lightning current.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.636-647
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• 2004

The objective of this paper is to provide an improved reorder decision policy for general multi-echelon distribution systems utilizing the shared stock information. It has been known that traditional reorder policies sometimes show poor performance in distribution systems. Thus, in our previous research we introduced the order risk policy which utilizes the shared stock information more accurately for the 2-echelon distribution system and proved the optimality. However, since the real world supply chain is generally composed with more than 2 echelons, we extend the order risk policy for the general multi-echelon systems. Since the calculation of the exact order risk value for general multi-echelon systems is very complex, we provide two approximation methods for the real-time calculation. Through the computational experiment comparing the order risk policy with the existing policies under various conditions, we show the performance of the order risk policy and analyze the value of the shared stock information varying with the characteristics of the supply chain.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.11a
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• pp.159-165
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• 2003

The objective of this paper is to provide an improved reorder decision policy for general multi-echelon distribution systems utilizing the shared stock information. Since it has been known that traditional reorder policies sometimes show poor performance in distribution systems, in our previous research we introduced the order risk policy which utilizes the shared stock information more accurately f3r the 2-echelon distribution system and proved the optimality. However, since the real world supply chain is generally composed with more than 2 echelons, we extend the order risk policy for the general multi-echelon systems. Since the calculation of the exact order risk value fur general multi-echelon systems is very complex, we provide two approximation methods. Through the computational experiment comparing the order risk policy with the existing policies under various conditions, we show the performance of the order risk policy and analyze the value of the shared stock information varying with the characteristics of the supply chain.