• Journal of Information Technology Services
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• v.11 no.2
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• pp.93-106
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• 2012

Recently, a Game Shut-down policy, partially limiting the time for the use of online game service, has been implemented in order to protect the youth from the excessive use of games by limiting their access to games in the late hours, based on the serious side effects of online games on the youth. However, the effectiveness of a Game Shut-down policy becomes a social issue. Thus, this study aims to investigate the alternative policies through the levels of the communications suggested by the theory of excellence, for the successful implementation of the policy. As a result of the study, the government and students, the recipient of those policies, need to strengthen their two-way communication in respect of the Game Shut-down policy, breaking from the existing views on the perception. The problem is that the current government's way of the communication for the Game Shut-down policy is one-way and it is aiming at achieving the objectives only. Thus, the communication in this manner will cause the side effect. 'the opportunistic violation of the system in the future', even if the students seemingly accept the system. Two-way communication will enhance the motivation for the voluntary acceptance of the system and lower the motivation for the opportunistic violation of the system. Thus, the government needs to strengthen two-way communication in the future.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.2
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• pp.120-126
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• 2010

This paper propose analysis and examination of the melting characteristic of fuse elements by repeating overcurrent as a depletion factor of high pressure current limiting fuse through test following existence and nonexistence of extinction material and various configuration of elements. To examine deterioration progress rate by repeating overcurrent we analyzed heat for various element notching configuration, designed plate type, ring type element and estimated the relationship with life span by analyzing breaking characteristic through repeating overcurrent test with adjusting load factor at Silicon Dioxide(SiO2) filled state or in air. A Crack by repeat stress, decrease of section and transformation by friction with extinction material by repeating overcurrent causes a problem which shortens life span based on fuse repeating frequency. Since the contents of this paper might be useful to research the correlation between friction of materials and repeating life span based on load factor of repeating current, the quality of product would be improved through solution of the problem.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.7
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• pp.981-986
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• 2018

AC(alternating current) CB(circuit breaker) at the fault occurred in the existing AC distribution system is limiting the fault current through zero cross-point. However, DC(direct current) CB does not have zero cross-point. Therefore, arc occurred by on-off operation of DC CB is very huge. Nowadays, many research team are studying the way to decrease breaking time, which is one of the essential conditions in DC CB. We suggested novel arc-induction type DC CB in this paper. The proposed arc-induction type DC CB is composed of the mechanical Arc ring and DC CB. We confirmed the operation of arc-induction type DC CB through the HFSS(High Frequency Structure Simulator) 3D simulation program and performed the experiment for operation characteristics. Results showed that arcing time of the arc-induction type DC CB by using induction ring was faster than existing mechanical DC CB. On the transient system, we confirmed stable operation characteristics of the arc-induction type DC CB through the simulation and experimental results. We expect that the proposed arc-induction type DC CB technology is will go to stay ahead of the existing DC CB technology.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.543-545
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• 2003

한류형 전력퓨즈는 계통의 단락사고로 고장 전류가 흐를 때 퓨즈내부에서 발생하는 저항에 의해 고장전류를 회로 고유의 단락전류보다 아주 적은 값으로 제한하고 최소 시간내에 차단하여 회로를 보호하므로 계통기기의 단락용량를 최소한으로 감소시킬 수 있다. 본 논문에서는 이러한 한류형 전력퓨즈의 단락전류 차단성능 평가를 위해 동작책무에 따른 차단성능을 규명하고자 단락발전기를 사용하여 단락전류차단시험을 실시하고 그 결과를 제시하였으며, 또한 차단과정에 따른 스트레스들이 단락시험 시 차단성능에 미치는 영향을 다루고 있다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.2
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• pp.278-283
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• 2013

With the increasing power demands, size of the fault current in electrical grids is steadily increasing, and it exceeds the breaking capacity of circuit breakers. To effectively cope with these problems, a high-speed interrupter was suggested. The high-speed interrupter provides fault current with a bypass to a fault current limiter in case of accidents and consequently, fault current can be restricted. In this study, behavioral characteristics of high-speed interrupter were analyzed by accident types occurred in a distribution system. When accidents occurred, a and b contact of the high-speed interrupter were turned-off and then, turned-on. Accordingly, fault current flowed to the circuit connected to a current limiting element, and the fault current limiter restricted fault current to within a half-cycle. Nevertheless, the behavior of the high-speed interrupter was slowed down by a switching surge. As a result, fault current was confirmed to be restricted not to within the anticipated half-cycle, but to after a half-cycle. Moreover, the behavioral characteristics of the high-speed interrupter changed not only by accident types, but by behaviors of R, S, and T phases. This was due to the errors in stroke lengths of the high-speed interrupters, which resulted in a slight time discrepancy among three interrupters. In addition, the switching behaviors of the b and a contact were confirmed not to have coincided due to the switching surge; b contact behaved first and a contact followed. because of this, accuracy of stroke length and switching surges through the solenoid suction increases may be necessary to resolve.

• Progress in Superconductivity
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• v.10 no.1
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• pp.60-67
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• 2008

We present domestic efforts for superconducting fault current limiter (SFCL) application in the Korea Electric Power Corporation (KEPCO) grid and pending points at issue. KEPCO's decision to upgrade the 154 kV/22.9 kV main transformer from 60 MVA to 100 MVA cast a problem of high fault current in the 22.9 kV distribution lines. The grid planners supported adopting an SFCL to control the fault current. This environment friendly to SFCL application must be highly dependent upon the successful development of SFCL having specifications that domestic utility required. The required conditions are (1) small size of not greater than twice of 22.9 kV gas insulated switch-gear (GIS), (2) sustainability of current limitation without the line breaking by circuit breakers (CB) for maximum 1.5 seconds. Also, optionally, recommended is (3) the reclosing capability. Conventional resistive SFCLs do not meet (1) $\sim$ (3) all together. A hybrid SFCL is an excellent solution to meet the conditions. The hybrid SFCL consists of HTS SFCL components for fault detection and line commutation, a fast switch (FS) to break the primary path, and a limiter. This characteristic structure not only enables excellent current limiting performances and the reclosing capability, but also allows drastic reduction of HTS volume and small size of the cryostat, resulting in economic feasibility and compactness of the equipment. External current limiter also enables long term limitation since it is far less sensitive to heat generation than HTS. Semi-active operation is another advantage of the hybrid structure. We will discuss more pending points at issues such as maintenance-free long term operation, small size to accommodate the in-house substation, passive and active control, back-up plans, diagnosis, and so on.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.1
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• pp.143-148
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• 2013

When the fault occurs in power system, the fault-current exceeds breaking capacity of the circuit breaker. So, reliablity of the power system is decreased sharply. Superconducting fault-current limiter (SFCL) is operated without impedance in normal state. The fault-current is limited by its impedance during the fault condition. However, the SFCL has several weak points such as huge size, high-price, liquid-nitrogen operation for the real power system. In this paper, We suggested the high-speed interrupter to limit the fault-current in case of the single line-to-ground fault. In addition, we compared the high-speed interrupter with the SFCL to ensure the operation reliability. The proposed interrupter detected the fault-current through the CT, and the power was supplied by operation of the SCR control system. In this experiment, the power of high-speed interrupter was applied after the 4.8[msec] from fault instant. The on-off operation of the interrupter was started after half-cycle from the fault. The fault-current was flowed into the impedance element by the switching operation of the high-speed interrupter. So, the fault current was limited within one cycle, and then it didnt exceed the capacity of a circuit breaker. We confirmed that there was slight difference between the SFCL with high-speed interrupter in terms of limiting-time of the fault-current and switching speed of the SCR. The high-speed interrupter was considered to be more efficient than the SFCL in size, cost or reliability.