• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.8
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• pp.1485-1491
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• 2011

This paper deals with the technical problems for the protection devices, by simulating test facilities of protection coordination for Photovoltaic systems. In order to analyze the operation characteristics for the protection devices in the case that the Photovoltaic systems with bi-directional power supply are located in the feeder, this paper proposes the test facilities composed of model distribution system, protection device and model Photovoltaic systems. By performing the simulation for operation characteristics for the protection devices based on the test facilities, this paper presents the malfunction mechanism for the protection devices. The test results show that this paper is practical and effective for the technical guideline for the Photovoltaic systems.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.351-358
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• 2004

When fault occur in power systems, the protective relay plays a roles of protecting power system according to its setting values. There, it is very important that the protective relay have high selectivity performance in power system by correct setting the relays. This paper analyzed protect device protect cooperation or Transient stability and apply to Overcurrent relay in the real power system operation environment by using EDSA Program.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.640-642
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• 1995

This paper describes the present state and development prospect on the protective relaying under high resistance earth faults in transmission systems. Especially it is difficult to detect the fault accompanied with high resistance contary to low resistance. In the complicated power system if the detection is failed, power failure will be occured in large area. New technology with respect to such a problem must be developed. This paper introduces research and development trend in home and abroad.

• Fibers and Polymers
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• v.4 no.3
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• pp.129-134
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• 2003

We have shown in Part I [1] of this study that medical needle-stick injuries are causing serious health problems to healthcare personnel and other professionals that require the attention of healthcare and textile researchers to develop new protective systems. Responding to such need, a needle force measurement device that is capable of measuring dynamic forces experienced by medical needles during needle penetration through protective articles was developed and described in part I. This paper reports the results of evaluation of protective woven fabrics from high performance fibers and standard and bifid medical needles using the force measurement system. The woven fabrics varied in cover factor, number of layers, and orientation angle. Standard and bifid needles with different gap widths were used to evaluate the resistance of the fabric to needle penetration.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.81-86
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• 2000

In recent modern protective systems have been introduced to reduce the vulnerability of bridges to seismic events. These protective systems include base isolation devices of different types, damping devices and active control devices. The objective of this study is to analytically evaluate the efficiency of a seismic retrofit scheme using base isolation systems, such as lead rubber bearings and sliding isolators. In this study, a triaxial model was used, which is capable of accurately developing the behavior of sliding isolators including the influence of the changing vertical force and velocity on the friction coefficients. Seismic response analyses of the bridge before and after retrofit were carried out by using a three-dimensional nonlinear seismic analysis program, IDARC-BRIDGE. To evaluate the efficiency of a retrofit scheme using triaxial isolators, a comparative study of performances of above two base isolation systems was conducted, and the numerical results show that the triaxial isolation solution can effectively reduce the sheat forces at the piers for the vertical ground motion.

• Corrosion Science and Technology
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• v.10 no.3
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• pp.95-100
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• 2011

Protective coatings play an important role in the protection of metallic structures against corrosive environment. The main function of anticorrosive coating is to prevent the materials from corrosive agents, such as water, oxygen and ions. In the study, the corrosion protection properties of urethane and epoxy coating systems were evaluated using EIS methods exposed to the corrosion acceleration test such as Norsok M501, Prohesion and hygrothermal cyclic test. AFM analysis of the coating systems was carried out to monitor the change of roughness of coatings. Urethane coating system was more stable than the epoxy coating under given cyclic conditions. Water uptake into the urethane coatings was less than that into the epoxy coating. The urethane coating system showed better corrosion protection than epoxy coating system based on the changes of the impedance modulus at low frequency region with exposure time. Consequently, the corrosion protection properties of the epoxy and urethane coatings was well correspond with their surface roughness changes and water uptakes.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.313-315
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• 2005

Recently There has been growing interest in new renewable energy systems with high-energy efficiency due to the increasing energy consumption and environmental pollution problems. But an insertion of new distributed generation to existng power distribution systems can cause several problems such as voltage variations, harmonics, protective coordination, increasing fault current etc, because of reverse power. This paper was applied to fault location defecting a method as each Relay sensing fault current value and carried out short-circuit analysis by MATLAB and PSCAD/EMTDC programs and identity the faulted section o f22.9[kV] distribution system interconnected a large number of distributed generation. The existing protection system of 22.9[kV] power distribution system analyzed and the study on protective coordination recloser and Sectionalzer accomplished

• Journal of the Korea Computer Industry Society
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• v.2 no.12
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• pp.1517-1522
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• 2001

In this paper, We propose digital protective relay which monitors the status of distribution line and controls power apparatus with real time operation. Digital protective relay improves the performance of basic functions which are measurement, display and communication. The Int one we consider is that the protective device has the standard method for protecting the distribution systems which are circuit brakers, switch and emergency generators. These are Protected by analog type Protective relay and devices. The security requirements should be activated within a few seconds, and with real time operation. The second one is an efficient method for adapting the one chip micro-processor(PIC16F84) which is enable to digital control system. The proposed methods are implemented with experimental results and have an high fidelity characteristics in local experiment tests.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.6
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• pp.75-81
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• 2013

In this paper, protection coordination between residual current devices and surge protective devices in low-voltage consumer's distribution systems are presented. In the case that a surge protrctive device(SPD) is located on the load side of an residual current device(RCD), when the surge is injected from the source side of the RCD, most of injected surge currents are split into the RCD and the protection coordination between the SPD and RCD is improper, three of 6 specimens experience unintended operation due to test impulse currents. Also when the surges is injected from the load side, a lot of the surge currents is split into the SPD, but a half of test specimens causes nuisance trip. Coordination between SPD and RCD is not valid. When installing SPD, it is important to select SPD after due consideration of the protection voltage level of metal oxide varistor embedded in RCD. It is expected that the results obtained from this work could be useful to improve the protection effects of SPD in low-voltage distribution systems.

• Journal of Wind Energy
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• v.14 no.3
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• pp.43-53
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• 2023

To improve AEP, wind turbine blade lengths are increasing every year. As the length of blades increases, the blade tip speed also increases. Because of the increased tip speed, the impact energy between the leading edge and raindrops also increases. The increased impact energy is the primary factor contributing to erosion of the blade's leading edge. Blade leading edge erosion reduces aerodynamic performance, increases repair costs, and causes downtime. Therefore, numerous studies are being conducted on protective solutions and RET systems to prevent and delay erosion of the blade's leading edge. However, few institutions in Korea research protective solutions and RET systems. In this study, we aim to develop a laboratory-scale RET system. The developed RET system was based on the ASTM G73-10 standard. As a result of the RET, it was confirmed that the erosion tendency was similar to that of overseas institutions. In addition, the effectiveness of the RET system was verified by a maximum erosion rate of 0.0023 for an epoxy-based protective solution.