• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.480-483
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• 2008

The cold-air distribution system is expected as an efficient method to reduce energy consumption in the air-conditioning system. We introduced some control strategies for the system by summarizing some references in the view point of energy saving. Direct digital control is specially emphasized as an important control technique for the system. Some drawbacks which habe been conventionally mentioned to apply the cold-air distribution to real fields can be solved by using the technique. The control strategy which is introduced in here will be available to build control system for the air-conditioning based on the cold-air distribution for energy saving.

• Journal of Electrical Engineering and Technology
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• 제9권2호
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• pp.628-634
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• 2014

This paper investigates the transient characteristics of grounding systems used in under-ground distribution power cables. Recently, two kinds of grounding system are used for underground distribution cables in Korea. The first one is conventional multi-point grounding system, the other is newly proposed non-bundled common grounding system. The non-bundled common grounding system has an advantage the decreasing the power loss due to decrease of the shield circulation current. In this paper, the lightning overvoltage induced in neutral wire (in case of non-bundled common grounding system, overvoltage between opened neural wires and grounding in each phase) of these two kinds of grounding systems are estimated and compared by field tests and EMTP simulations. The EMTP simulation methods are firstly verified by comparison of measurement and simulation. Finally, the insulation level against lightning is expected by EMTP simulation results using verified model.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 춘계학술대회논문집
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• pp.283-287
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• 2005

In this paper, one general approach is proposed for the design of power system that can be applicable for next generation LEO satellite application. The power system consists of solar panels, battery, and power control and distribution unit(PCDU). The PCDU contains solar array modules, battery interface modules, low-voltage power distribution modules, high-voltage distribution modules, heater power distribution modules, on-board computer interface modules, and internal DC/DC converter modules. The PCDU plays roles of protection of battery against overcharge by active control of solar array generated power, distribution of unregulated electrical power via controlled outlets to bus and instrument units, distribution of regulated electrical power to selected bus and instrument units, and provision of status monitoring and telecommand interface allowing the system and ground operate the power system, evaluate its performance and initiate appropriate countermeasures in case of abnormal conditions. We review the functional schemes of the main constitutes of the PCDU such as the battery interface module, the auxiliary supply module, solar array regulators with maximum power point tracking(MPPT) technology, heater power distribution modules, spacecraft unit power distribution modules, and instrument power distribution module.

• KIEE International Transactions on Power Engineering
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• 제4A권1호
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• pp.11-17
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• 2004

It becomes difficult and high in cost to construct new ducts and/or tunnels for power cables in domestic areas. This paper presents possible strategy of an HTS distribution cables for distributing electric power in local areas as niche marketing. Reflected were its important distinction such as system configuration, rationale, establishment of strategy and considerably high economical efficiency compared with present underground cables. In this paper, applicable important items by using HTS distribution cables in water pumping powerhouse and distribution substation as example objective regions were reviewed. Based on this, the following items on distribution HTS system are examined. (I)A review of constructing a model system to introduce high temperature superconducting distribution cables to objective areas is presented. (2)The strategy to capture HTS distribution cable in water pumping powerhouse and distribution substation as niche marketing regions were reviewed. (3)In concrete, system configuration, rationale, establishment of strategy and considerably high economical efficiency are reviewed between existing cable and HTS one.

• 전기학회논문지
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• 제59권10호
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• pp.1741-1747
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• 2010

The development of overload management systems for distribution transformers offers new opportunities for improving the reliability of distribution systems. It allows network planners to optimize the system resource utilization and investment cost. Such an improvement in the flexibility of the distribution network is only possible if the operator has more accurate knowledge of the realtime conditions of distribution transformers. In this paper, we present an improved overload decision system for distribution transformers using realtime monitoring data. Our study can be categorized into two parts: (a) improvement in the criteria for judging the overload conditions of distribution transformers and (b) development of an overload evaluation system using realtime monitoring data. In order to determine the overload criteria, overload experiments are performed on sample transformers; the results of these experiments are used to define the relationship between the transformer overload and the increase in the top-oil temperature. To verify the accuracy of the experimental results, field tests are performed using specially manufactured transformers, the loads and top-oil temperatures of which can be measured. For arriving at online overload decisions, we propose methods whereby the measured load curve can be converted into an overload characteristic curve and the overload time can be calculated for any load condition. The developed system is able to evaluate the overload for individual distribution transformers and calculate the losses using realtime monitoring data.

• 전력전자학회논문지
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• 제22권4호
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• pp.353-359
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• 2017

To take advantage of electric propulsion, several large vessel kinds, namely, cruise vessels, icebreakers, drill ships, and warships, have been generally designed with Integrated Power System (IPS). Although most of these vessels have adopted AC distribution IPS, DC distribution IPS ships have recently emerged as a new promising technology thanks to the availability of the products related to the DC distribution system, in which the system's major advantages over AC distribution are reduced weight and fuel consumption. This paper presents the comparison results of a 10-t class fishing boat for the AC distribution and DC distribution cases. By replacing AC distribution system with DC distribution, 31-41% reduction in the weight of the electrical equipment weight and 20-25% reduction in the fuel consumption are expected.

• KIEE International Transactions on Power Engineering
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• 제2A권3호
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• pp.102-108
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• 2002

Due to the many attractive aspects of DG in the future power distribution system, distribution automation will be a center hub of integration of the distribution system and resources to satisfy the various needs of customers in a competitive and deregulated environment. In this paper, operation strategies are presented which use network reconfiguration of the automated distribution systems with DG as a real-time operation tool for loss reduction and service restoration from the view of distribution operation. The algorithms and operation strategies of an automated distribution system with DG are introduced to achieve the positive effects of DG in distribution systems. A simple case study shows the effectiveness of the proposed operation strategies.

• 유통과학연구
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• 제3권2호
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• pp.15-28
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• 2005

본 연구는 소비자 니즈의 변화에 따른 식품컨셉의 변형으로 인한 일본의 식품유통시스템의 발전과정을 살펴보는 것을 연구의 목적으로 한다. 본 논문에서는 식품컨셉으로서 일반적으로 가공식품과 비가공식품으로 분류되었던 식품컨셉을 확장시켜 비가공적 가공식품과 가공적 비가공식품의 개념을 소개하고, 그에 따른 일본식품유통시스템의 물류, 도매, 소매상에서의 혁신적 관리 및 발전과정을 살펴본다. 일본 식품유통시스템의 변화에 근본적인 원인을 제공한 요인으로서 소비자 니즈와 인식의 변화를 들 수 있으며, 일본 식품유통시스템의 개념정립 및 현황분석과 함께 일본 식품유통시스템의 실제적 변화로서 온도대별 물류혁신, PB상품개발, 체인시스템의 다양화 등을 살펴보기로 한다. 이와 같은 일본소비자의 특성, 식품유통시스템의 발전상황 및 사례를 연구함으로써 한국식품유통시스템의 발전과정과 비교분석이 가능하며 나아가 합리적인 식품유통시스템으로의 방향제시가 가능하다고 사료된다.

• KIEE International Transactions on Power Engineering
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• 제5A권3호
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• pp.286-292
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• 2005

As the power industry moves towards open competition, there has been a call for methodology to evaluate power system reliability by using composite interruption cost. This paper presents algorithms to evaluate the interruption cost of distribution power systems by taking into consideration the failure source and the composite customer interruption cost. From the consumer's standpoint, the composite customer interruption cost is considered as the most valuable index to estimate the reliability of a power distribution system. This paper presents new algorithms that consider the load by customer type and failure probability by distribution facilities while calculating the amount of unserved energy by customer type. Finally, evaluation results of unserved energy and system interruption cost based on composite customer interruption cost are shown in detail.

• 전기학회논문지
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• 제65권8호
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• pp.1317-1325
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• 2016

This paper identifies the issues of contingency analysis for restoration in distribution systems. Contingency analysis has been applied to transmission systems but not to distribution systems. The distribution system is different from transmission system. So it is hard to apply for existing contingency analysis to distribution system. In this paper, a new contingency analysis method for distribution systems is proposed. The proposed method is based on service restoration capability. It aims to minimize outage left after service restoration in case of a fault in advance. The method estimates the vulnerability which is represented by zone restoration index proposed in [1]. Applying the proposed method, operators could change the system so that it does not leave any outage left after restoration. Case study has been carried out on a five feeder system and its results show effectiveness of the method.