• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.86-89
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• 1993

This paper contains the various effect of distribution feeder sectionalizing by distribution automation. The effect by automatic sectionalizing switch and the effect by manual switch are analyzed and shown according to the radial feeder and the loop feeder respectively. Based on the reliability analysis, the reference for the feeder division and sectionalization is recommended. Also, the necessary number of manual switch where the automatic switch is installed is recommended through the reliability analysis.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.2
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• pp.73-78
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• 2020

In this study, a novel reactive power control scheme is proposed to supply stable reactive power to the distribution line by compensating a ripple voltage of DC link. In a single-phase system, a magnitude of second harmonic is inevitably generated in the DC link voltage, and this phenomenon is further increased when the capacity of DC link capacitor decreases. Reactive power control was performed by controlling the d-axis current in the virtual synchronous reference frame, and the voltage control for maintaining the DC link voltage was implemented through the q-axis current control. The proposed method for compensating the ripple voltage was classified into three parts, which consist of the extraction unit of DC link voltage, high pass filter (HPF), and time delay unit. HPF removes an offset component of DC link voltage extracted from integral, and a time delay unit compensates the phase leading effect due to the HPF. The compensated DC voltage is used as feedback component of voltage control loop to supply stable reactive power. The performance of the proposed algorithm was verified through simulation and experiments. At DC link capacitance of 375 uF, the magnitude of ripple voltage decreased to 8 Vpp from 74 Vpp in the voltage control loop, and the total harmonic distortion of the current was improved.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.722-723
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• 2011

국가차원의 신재생에너지 활성화 방안에 따라 지자체 등의 분산전원 시설계획이 점차 증가하고 있다. 이에 따라서 기존의 radial 구조가 아닌 closed loop을 운영하기 위해서는 보호협조에 대한 문제가 확실히 해결되지 않고서는 계통을 안정적으로 운영할 수 없다. 따라서 본 논문에서는 radial 계통 및 계통이 변경되거나 분산전원이 연계 시 closed loop 구조를 가지는 계통의 보호기기 및 자동화 개폐기들을 Agent화 시켜 통신을 이용한 보호 및 고장 구간 분리 알고리즘을 제안 하고자 한다.

• Proceedings of the KOSOMBE Conference
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• v.1994 no.05
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• pp.85-87
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• 1994

This paper proposes a new inductance minimization scheme for a gradient system of arbitrarily selected shape. Although it is important to minimize the gradient coil inductance to reduce the current switching time, such minimization has been possible only for cylindrical or parallel biplanar coils. By using small current loops on arbitrarily selected surface as optimization elements, the inductance of the whole circuit can be minimized using the loop's self- and mutual-inductances. Wire positions can be easily derived from the loop current distribution. Preliminary studies for the design of x-directional surface gradient coil show the utility of tile proposed gradient coil design scheme.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.670-672
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• 2005

발전원이 다른 계동으로 연계된 춘천, 남춘천변전소의 태전선로간 Loop 시행시 일부배전선로가 Trip되는 현상에 대하여 PSSE 검토 TOOL을 활용하여 계통을 모의하고 변압기 병렬운전조건에 대한 물리적 의미와 검토대상 배전선로 계통특성, 주변 발전원의 발전력과의 상관관계를 기술검토를 통하여 계통특성을 분석함으로써 Loop시행이 가능한 계통여건을 파악, 선로 운영의 최적방안을 제시하고자 한다.

• Nuclear Engineering and Technology
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• v.48 no.4
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• pp.975-981
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• 2016

The containment response during the first 24 hours of a low-pressure severe accident scenario in a nuclear power plant with a two-loop Westinghouse-type pressurized water reactor was simulated with the CONTAIN 2.0 computer code. The accident considered in this study is a large-break loss-of-coolant accident, which is not successfully mitigated by the action of safety systems. The analysis includes pressure and temperature responses, as well as investigation into the influence of spray on the retention of fission products and the prevention of hydrogen combustion in the containment.

• KEPCO Journal on Electric Power and Energy
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• v.8 no.1
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• pp.15-19
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• 2022

The radial distribution systems (RDS) commonly used around the world has the following disadvantages. First, when the DL is operated on a radial system, the line utilization rate is usually kept low. Second, if a fault occurs in the radial DL, a power outage of 3 to 5 minutes is occurring depending on the operator's proficiency and fault situation until the fault section is separated and the normal section is replaced. To solve this problem, Various methods have been proposed at domestic and foreign to solve this problem, and in Korea, research is underway on the advanced system of operating multiple linked DL always. A system that is electrically linked always, and that is built to enable high-speed communication during the protection coordination is named networked distribution system (NDS). Because the load shares the DL, the line utilization rate can be improved, and even if the line faults, the normal section does not need to be cut off, so the normal section does not experience a power outage. However, since it is impossible to predict in which direction the fault current will flow when a failure occurs in the NDS, a communication-based protection coordination is used, but there is no backup protection coordination method in case of communication failure. Therefore, in this paper, we propose a protective cooperation method to apply as a backup method when communication fails in NDS. The new method is to change TCC by location of CB using voltage drop in case of fault.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.5
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• pp.43-49
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• 2008

Motivated by the Communication Broadcasting Convergence service, various technical approaches are being used to develop more efficient antenna models. This paper proposes a compact mobile antenna which is attachable to a cell phone and is applicable for Communication Broadcasting Convergence. In the design of the antennas for mobile handsets, size reduction is a crucial factor. In this paper, the compactness of a loop antenna is realized by bending a folded-dipole. A short planar dipole is transformed to a twice folded dipole and a loop antenna to produce a larger input resistance. The current distribution of the antenna is the same as a loop antenna, and its radiation patterns are omni-directional. We also analyze the performance of the RFID antenna by exploring the current-induced near field radiation patterns using a electro-optic field mapping system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.9
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• pp.433-440
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• 2002

The addition of switches to a distribution feeder does, in general, increase reliability by decreasing the duration of the outage of many to the customers on the feeder. To cover its service area so that feeder-level delivery reaches sufficiently close to all customers, feeders typically split their routes many times, in what is often called a lateral feeder. It is interesting to note, however, that the effectiveness of a switch is very much dependent on the types of lateral feeder. The types of lateral are classified into two types. The first is loop lateral feeder that can connect its load to an adjacent feeder through a tie line in case that a fault occurs in its feeder and it is laid out so that every feeder has complete fault backup through re-switching of its loads to other sources like a main feeder The second is the radial lateral feeder cannot connect its load to an adjacent line, no provision is made for contingency backup of feeders. There are no other circuits in the radial lateral feeder form which to restore power. In this study, we evaluate the effectiveness of a switch installation between on the radial and loop lateral feeders to increase reliability by decreasing the duration of the outage. These results can help power utility to design the switch layouts on the radial and loop lateral feeder system.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.5
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• pp.81-90
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• 2014

It is an element certainly required for the cost reduction of a company that forward and reverse logistics chain are unified and constitutes a resource closed-loop supply chain (CLSC). In this study, the inventory control which unifies inventory of distribution centers (DCs) of forward logistics and processing center of reverse logistics in the CLSC environment is proposed. The inventory system model for newly-constructed CLSC considers the JIT(Just-In-Time) delivery from the processing center to the manufacturer, including the making of decisions on whether to wait for the arrival of end-of-life products or to back-order necessary products for manufacturer when the supply of end-of-life products at the processing center via the returning center is insufficient for the demands of the manufacturers. The validity of the proposed model was verified using the genetic algorithm (GA). In order that a parameter might investigate the effect which it has on a solution, the simulation was carried out for priGA(priority-based GA) on three kinds of parameter conditions. Moreover, mhGA(modified hybrid GA) to which a parameter is adjusted for every Study on Reducing Logistics Costs and Inventory Control System according to facilities integration in the Closed-Loop Supply Chain Environment generation, the simulation was carried out to a four-kind numerical example.