• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.204-205
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• 2006

This paper describes the protective ability of lightning arrestor in combined distribution system with power cable. To evaluate the protective ability, change of arrestor and grounding location are considered. On the other hand, arrestor developed by Cooper Power Systems for underground power cable system, is considered to evaluate surge protective ability as in underground system, when arrestor occurs failure has overhead line. The result shows that lightning arrestor in combined distribution system with power cable protect effectively when failure at arrestor in overhead line. On the other hand, arrestor developed by Cooper Power Systems for underground power cable system, is considered to evaluate surge protective ability in underground distribution system, when arrestor of overhead line has failure. The result shows that lightning arrestor installed in underground cable can effectively protected cables from surge when arrestor of overhead line has failure. And also even though grounding locations are decreased, it is revealed that protective ability is nearly similar.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1174-1179
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• 2004

In general, the national rail system put an emphasis on distribution planing of stations for smooth operation of transporting goods, train allocation, parking, and maintenance. Since the national rail system is operated on the ground level, it is feasible to improve various aspects of the system during its operation. On the contrary, urban rail system is operated in the limited space under the ground, and thus, improving various aspects of the system during its operation is infeasible. Specifically, the urban subway system must have a comprehensive track distribution plan because the urban subway system has to operate in a limited environment such as it operates in a much shorter time period, The subway system has to be ready for various operations and events such as trains returning in the opposite direction. parking trains that need repair, parking during night time, storing various maintenance equipments, and connections to other tracks. Furthermore, considering the future extension of tracks, a comprehensive track distribution plan is a must.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.9
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• pp.506-512
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• 2003

In this paper, a communication module between Relay agents in a multi-agent system based power distribution network protection system is realized using DNP3.0(Distributed Network Protocol), which is the standard communication protocol of distribution automation system in KEPCO. The key words for agent communication in the multi-agent based protection system are defined and represented by use of DNP application function code. The communication module developed based on the proposed communication scheme is tested by use of the Communication Test Harness, a test tool for DNP protocol, then used to the multi-agent system based power distribution net work protection system.

• Journal of the Korean Society of Safety
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• v.25 no.2
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• pp.24-28
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• 2010

The nuclear power Plant onsite AC electrical power sources are required to supply power to the engineering safety facility buses if the offsite power source is lost. Typically, Diesel Generators are used as the onsite power source. The 125 VAC buses are part of the onsite Class 1E AC and DC electrical power distribution system. The DC power distribution system ensure the availability of DC electrical power for system required to shutdown the reactor and maintain it in a safety condition after an anticipated operational occurrence or a postulated Design Base Accident. Recently, onsite DC power supply system trip occurs the loss of system function. To obtain the performance such as reliability and availability, we analyzed the cause of battery charger trip and described the improvement of DC power supply system reliability. Finally, we provide reliability performance criteria of charger in order to ensure the probabilistic goals for the safety of the nuclear power plants.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.3
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• pp.138-147
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• 2017

As the functions and structure of the system are complicated and elaborated, various types of structures are emerging to increase reliability in order to cope with a system requiring higher reliability. Among these, standby systems with standby components for each major component are mainly used in aircraft or power plants requiring high reliability. In this study, we consider a standby system with a multi-functional standby component in which one standby component simultaneously performs the functions of several major components. The structure of a parallel system with multifunctional standby components can also be seen in real aircraft hydraulic pump systems and is very efficient in terms of weight, space, and cost as compared to a basic standby system. All components of the system have complete operation, complete failure, only two states, and the system has multiple states depending on the state of the component. At this time, the multi-functional standby component is assumed to be in a non-operating standby state (Cold Standby) when the main component fails. In addition, the failure rate of each part follows the Weibull distribution which can be expressed as increasing type, constant type, and decreasing type according to the shape parameter. If the Weibull distribution is used, it can be applied to various environments in a realistic manner compared to the exponential distribution that can be reflected only when the failure rate is constant. In this paper, Markov chain analysis method is applied to evaluate the reliability of multi-functional multi-state standby system. In order to verify the validity of the reliability, a graph was generated by applying arbitrary shape parameters and scale parameter values through Excel. In order to analyze the effect of multi-functional multi-state standby system using Weibull distribution, we compared the reliability based on the most basic parallel system and the standby system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.1
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• pp.103-112
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• 2015

Recently, DC distribution system has come into the spotlight as the number of digital loads and the use of renewable energy increases. However, there are still challenges for the commercialization of DC distribution system such as a consideration for the safety. Thus, researches on protective coordination and grounding system for the safety of human bodies and facilities in Low-Voltage DC (LVDC) distribution system should be preferentially conducted. In this paper, therefore, we analyze characteristics of faults in LVDC system accroding to type of grounding system based on IEC 60364. Finally, the simulations for fault characteristic in different grounding scheme are conducted using ElectroMagnetic Transient Program(EMTP) and the results of simulation are shown.

• Journal of the military operations research society of Korea
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• v.30 no.2
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• pp.50-62
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• 2004

Every year, about 250,000 new recruits enter the military under the R.O.K military draft system. When the fresh soldier groups arrived at the Recruit Training Center, their supplies are distributed before they get basic military training. The supplies are divided by season, summer and winter. There are 14 class of summer items and 20 class of winter items, and the each class has about a few kinds of items. Totally, there are the hundreds kinds of supplies and the supplies distribution system is manually operated. However, in the current system, many problems such as spending a lot of time, manpower and high change rate due to the inaccurate distribution have been raised. This paper suggests the automated supplies distribution system to solve the above problems. We choose the appropriate facilities in the system by using the AHP(Analytic Hierarchy Process) and analyse the operating efficiency of the new system by simulation. The new suggested system shows about $39.25\%$ improvement in throughput and 3.75 times reduction of manpower compared to the current system.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2042-2048
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• 2014

In medium voltage electrical distribution networks, reforming the loss reduction is important, and in line with this, the issue of system engineering and use of proper equipment Expansion of distribution systems results in higher system losses and poor voltage regulation. Therefore, an efficient and effective distribution system has become more important. So, proper selection of conductors in the distribution system is crucial as it determines the current density and the resistance of the line. Evaluation of aging conductors for losses and costs imposed in addition to the careful planning of technical and economic networks can be identified in the network design. In this paper the use of imperialist competitive algorithm; genetic algorithm; is proposed to optimal branch conductor selection and reconstruction in radial distribution systems planning. The objective is to minimize the overall cost of annual energy losses and depreciation on the cost of conductors to improve productivity given the maximum current carrying capacity and acceptable voltage levels. Simulations are carried out on 69-bus radial distribution network using genetic algorithm approaches to show the accuracy as well as the efficiency of the proposed solution technique.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.4
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• pp.476-483
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• 2014

This paper describes the operational analysis results of the bipolar DC distribution system coupled with the distributed generators. The energy management for AC/DC power trade and the operational principle of distributed generators and energy storages were first analyzed by computer simulation with PSCAD/EMTDC software. After then a hardware simulator for the bipolar DC distribution system was built, which is composed of the grid-tied three-level inverter, battery storage, super-capacitor storage, and the voltage balancer. Various experiments with the hardware simulator were carried out to verify the operation of bipolar DC distribution system. The developed simulator has an upper-level controller which operates in connection with the controllers for each distributed generator and the battery energy storage based on CAN communication. The developed hardware simulator are possible to use in designing the bipolar DC distribution system and analyzing its performance experimentally.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.3
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• pp.117-124
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• 2007

This paper is about the Extra-High voltage distribution system in the customer's area. The power loss in the distribution system in the customer's area is disregarded and rarely managed so far. But, economically, this loss is not small quality to ignore. So, in this paper, we calculate the power loss of the Extra-High voltage distribution system in the customer's area by changing the locations of power transformer and other power facilities to decrease power loss in decreased secondary line length. And we also show the payback time of the proposed Extra-High voltage distribution system in the customer's area by simplified calculations.