• Journal of Mechanical Science and Technology
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• 제14권4호
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• pp.380-392
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• 2000

A typical production-distribution system consist of three main echelons representing the retailer, distributors, and a factory each with an on-site warehouse. The system is sufficiently general and realistic to represent many industrial situations. However, decision functions and parameters have been selected to apply particularly to the production and distribution of consumer durables. The flows included in the model are materials, orders, and those information flows needed to support the material and order-rate decisions. In this work, a realistic production-distribution system has been used as a basic model, which consists of three sectors: retailer, distributor, and factory. That system is a nonlinear 25th-order continuous system interconnected between the echelons. Using a modern control algorithm, a typical multi-echelon production-distribution system using a dynamic controller is numerically simulated in the nominal plant and in the perturbed plant when the piecewise constant manufacturing decision is limited by a factory manufacturing upper-limit due to capital equipment, manpower, and factory lotsize.

• 전기학회논문지
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• 제58권10호
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• pp.1835-1841
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• 2009

We analyze the problem of recloser-fuse coordination when a superconducting fault current limiter (SFCL) is installed to a power distribution system. Generally, The recloser is installed to upstream of fuse to protect against both permanent fault and temporary one appropriately. However, in a power distribution system with SFCL, the fault current is decreased by the effect of the impedance value of the SFCL and when a permanent fault occurs, the fuse may not melt during the last delay operation of the recloser because of the insufficient heat from the decreased current. Therefore, when SFCLs are applied into a power distribution system, the rating of the fuse has to be reselected to coordinate recloser to fuse effectively. To solve these problems, this paper analysed the operation of recloser-fuse coordination and presented the improved recloser-fuse coordination method in a power distribution system with SFCL using PSCAD/EMTDC.

• 조명전기설비학회논문지
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• 제28권6호
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• pp.113-121
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• 2014

At the end of the 19th century, a battle known as the War of the Currents was fought over how electricity would be generated, delivered, and utilized. In this day and age, there has been a growing interest in Green Growth policies as countermeasures against global warming. As a result of these policies, the use of new and renewable energy needed a power converter to replace fossil fuels has expanded. To reduce power consumption through high efficiency of conversion, Low Voltage DC (LVDC) distribution systems are suggested as an alternative. In a DC distribution system, DC loads are very efficient due to decrease the stages of power conversion. If the LVDC distribution system is adopted, not only DC load but also existing AC loads should be connected with LVDC system. Thus, the modeling of two loads is needed to analyze the DC distribution system. This paper, especially, is focused on the modeling of resistive load and electronic load including power electronic converters using ElectroMagnetic Transient Program (EMTP) software.

• 조명전기설비학회논문지
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• 제29권11호
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• pp.89-95
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• 2015

As a solution of improving the energy efficiency in power system, Low Voltage DC (LVDC) distribution systems different from conventional ones have been constantly researched. As in conventional AC distribution system, LVDC distribution system can suffer from High Impedance Fault (HIF) which may cause a failure of protective relay due to relatively low change in magnitude of fault current. In order to solve the problem, a scheme for detecting HIFs is presented in this paper. Closing Opening Difference Operation (CODO) based on Mathematical Morphology (MM), one of the MM-based filters, is utilized to make fault signals discriminable. To verify performance of the scheme, a simple LVDC distribution system is modeled by using ElectroMagnetic Transient Program (EMTP) software. Computer simulations according to various conditions are performed and comparison studies with a scheme using Wavelet Transform (WT) in an aspect of simulation time are also conducted.

• 한국정보통신학회논문지
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• 제12권6호
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• pp.1064-1069
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• 2008

본 논문은 인터프레임 확률분포에 의한 비디오 감시 시스템 설계 구현에 관한 것이다. 시스템은 비디오 분석 알고리즘과 표준 JPEG 압축 알고리즘을 처리하기 위해 고성능 DSP 프로세서 기반으로 구현된다. 비디오 분석은 가중치, 평균, 분산의 3변량정규분포에 의한 인터프레임 확률분포 분석을 이용하여 특정 영역에 물체를 검출하는 알고리즘을 사용한다. 실험 결과, 시스템 처리시간이 D1$(720{\times}480)$ 영상 프레임 당 85ms 소요되었고 초당 12프레임 정도 처리한다. 규칙에 따른 특정영역 물체감시는 움직임 빠르지 않는 물체에 대해 100% 검출되었다.

• 유통과학연구
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• 제2권2호
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• pp.1-15
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• 2004

The distribution companies in Korea usually specify the buying system in jikmeip, tukjeongmeip, imdeeul, and imdegap. In this view, the development of distribution companies in Korea is highly dependent on the which business status is emphasized. And it is considered critical to identify the important features of each buying system and the impact these systems have on each business status. Subsequently, the purpose of this study is to identify the said features and impact. With this study, we have tried to explore a new vision for distribution taking a consideration of the fact that most studies within Korea are oriented in marketing standpoint. Particularly, we have intended to analyze the distribution industry in the view of internal standpoint of a distribution company.

• Journal of Power Electronics
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• 제7권4호
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• pp.286-293
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• 2007

This paper proposes a distribution voltage control method when a voltage increase condition occurs due to reverse power flow from the clustered photovoltaic (PV) system. This proposed distribution voltage control is performed a by distribution-unified power flow controller (D-UPFC). D-UPFC consists of a hi-directional ac-ac converter and transformer. It does not use any energy storage component or rectifier circuit, but it directly converts ac to ac. The distribution model and D-UPFC voltage control using the ATP-EMTP program were simulated and the results show the voltage increase control in the distribution system.

• KIEE International Transactions on Power Engineering
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• 제4A권1호
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• pp.42-47
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• 2004

This paper presents the various application programs for the Distribution Automation System (DAS) of the Korea Electric Power Corporation (KEPCO)'s distribution system. These programs are developed to allow for optimal operation in the areas of feeder automation, relay coordination, loss minimization and so on. They are single line diagram auto creation programs for the feeder, service restoration program, protection coordination program, data error detection program, and optimal network reconfiguration program. The details of these programs are presented for validity and effectiveness.

• 대한안전경영과학회지
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• 제3권3호
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• pp.77-86
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• 2001

An operational strategy for inventory control on finished goods in the distribution system has been given attention to many enterprises and many studies regarding this field have been done and is also on-going currently. Many of these studies represented a large scale distribution network with a unified formulation by using defined symbols. These methods have provided the systematic approach of the distribution network but they are impossible to applying the reality system due to not considering the service rate of demand and treating the shortage of inventory. In order to overcome these unrealistic problems, the novel safety stock policy of responding to customers' inventory distribution network is suggested. this paper explores the transportation between Central Distribution Center(CDC) and Regional Distribution Center(RDC). Especially, the relation of transportation cost between CDC and RDC and cost of inventory control according to safety inventory with service level are emphasized. We could obtain the good results of this study by determining the optimal safety stock considering the various variables and constraints.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 A
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• pp.115-117
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• 2002

In general, it is supposed that load characteristics of high and low voltage distribution line are always coincidence. But in practical distribution system, voltage variation characteristics of high and low voltage distribution line are not same. Then in this paper, we proposes a voltage regulation method considering load variation characteristics of high and low voltage distribution line in distribution system.