• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.5
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• pp.248-252
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• 2004

Since DC ground resistance, which is a good index of the performance of a grounding system in low frequency. does not show the performance in transient state. We measured ground impedances in frequency domain ranging from 0.1 Hz to 900 KHz maximum to quantify the transient grounding performance of 4 types of grounding system. Transfer function was derived from the measured frequency-dependant ground impedance of a grounding grid. A simulation has been performed to verify the transfer function using EMTP (Electro-Magnetic Transient Program).

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.134-136
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• 2003

The deregulated electricity market is operated with respect to theory of economical efficiency, and therefore, the system operator requires data with fast contingency ranking for security of the bulk power system. This paper compares the weather dependant probabilistic risk index(PRI) with the system performance index for power flow in the IEEE-RBTS. also, the system performance index for power flow presents the power system stability. The probabilistic risk index can be classified into normal weather and adverse weather. This paper proposes calculation method using the probabilistic risk index in determining contingency ranking requiring for security under the deregulated electricity market.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.9
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• pp.1141-1145
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• 2018

Generally, in nuclear plants, distance relay (21R) has adapting to protect and to operate main protective of transmission lines and backup protective of main generator. Operation of 21R was required and based on exactly accurate calculation and criteria. But presently method of 21R setting has applied according to protection devices operation guide of KPX, excepting IEEE and ISA standards, which have a difference review directions, consider parameters and devices, also consideration factors were affected to relay operations by uncertain guides. therefore this paper proposed new protection relay setting method and unvague criteria from IEEE 741 and ANSI/ISA 67.04.01, and reviewed a different results through numerical calculation results for methods and criteria including previous and established 21r setting by IEEE, ANSI/ISA Technical standards.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.340-341
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• 2007

Thin film of ZnO was deposited on various substrate by Nd:YAG Pulsed Laser Deposition(PLD) with a wavelength of 355nm. Further more, Thin filme of ZnO conducted by various temperature conditions. The surface morphology of the ZnO thin film was investigated by X-Ray Diffraction(XRD) and Atomic Force Microscopy(AFM). Effects of various substrates and Temperature conditions were analyzed. The best properties were obtained on $600^{\circ}C$ with post-deposition annealing at $600^{\circ}C$ in flowing $O_2$ atmosphere for several hours.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.354-356
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• 2005

Novel structure ultrasonic motors which have cross type stator were designed and fabricated. Driving characteristics of the motors were analyzed and measured by changing the materials of the stator. This ultrasonic motor has stator with hollowed cross bar and the stator rotate the rotor using elliptical displacement of the inside tips. This motion is generated by lateral vibration mode of cross bars. This stator was analyzed by finite element analysis and the ultrasonic motors were made by analyzed results. The larger displacements were obtained, when the Young's modulus was increased and the Poisson's ratio was decreased. The fabricated one has high speed in large Poisson's ratio and Young's modulus. And the torque was increased in high Young's modulus.

• Journal of Power System Engineering
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• v.18 no.4
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• pp.85-90
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• 2014

In this paper, the transient thermal and residual stress analysis of the welding of 9% Ni steel plates using the FEA software ABAQUS are presented. The 9% Ni steel plates are welded manually with welding consumables of 70% Ni based Inconel type super-alloys (YAWATA WELD B (M)), producing a multi-pass/multi-layer butt weld. For these materials, temperature dependant mechanical and thermal material properties are used in the analysis. The back gouging is considered in welding process simulation. The FE thermal results are validated by comparing the real fusion profile and heat affected zone (HAZ). In addition, the continuous indentation test was conducted to measure the strength of base metal, HAZ and weld metal.

• Transactions of Materials Processing
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• v.13 no.5
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• pp.441-448
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• 2004

Heat treatment is one of the critical manufacturing processes that determine the quality of a product. This paper presents experimental and analytical results for the quench of a ring gear in stagnant oil. The goal of this study is to develop heat transfer predicting model in an overall analysis of the quenching process, Thermal conductivities which are dependant on temperatures and convection coefficients which are obtained by inverse method are used to develop the accurate heat transfer model. The results of heat transfer model have a good agreement with experimental results.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.139-147
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• 1999

Rapid Prototyping has made a drastic change in all industries which needs to reduce the time for the development of new products. Orientation and packing in rapid prototyping is considered as the most important factors to maximize the utilization of space in the build chamber and reduce build time. However, the decision of these parameter is mainly dependant on the operators's experience. This paper presents the methodology to find the optimal build layout considering an orientation and packing of multiple parts in SLS processing. Each part is represented as a voxel structure to deal with the inefficiency in a bounding box approach. Test results show that the adapted BL algorithm with a genetic algorithm(GA) can be applicable to a real industry.

• The Journal of the Korean Society for Microbiology
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• v.22 no.2
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• pp.185-193
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• 1987

Ten species of herbae, which have been used to treat cancers in Chinese medicine, were tested to investigate their mutagenicity or antimutagenicity in S. typhimurium TA97, TA98, TA100, TA1535, and TA1538. Scolopendra centipede was weakly active in reversion of the frameshift mutation in S. typhimurium TA97 strain and the base-pair substitution in TA100 and TA1535 strains. Other herbae such as Coix lachryma, Dianthus superbus, Tricanthoshse kirilowii, Eupatorium formosanum, Lithospermum erythrorhizon, Ansaema japonicum, Curcuma zedoaria, Helicteres angustifolia, and Euonymus sieboldianus did not show any of the mutagenic potential, regardless of the metabolic activation with rat hepatic microsomal fraction. Dianthus superbus, Eupatorium formosanum, and Euonymus sieboldianus exhibited suppressive activities on microbial mutagenesis of N-methyl-N'-nitrosoguanidine, a base-pair substitution mutagen, in TA1535 and TA100 tester strains. The antimutagenic activities of Dianthus superbus and Euonymus sieboldianus appeared to be dose-dependant.

• Proceedings of the KIEE Conference
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• summer
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• pp.165-167
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• 2004

End-user electric power consumption trends shows various load curves dependant on industry, contract, season, day and time. Analysis of end-user electric power consumption trends has a key role to efficiently meet electricity demand. There are several factors of change in electricity demand such as the change of weather, international conflict, and industrial trends during summer. This paper has analyzed the analysis the end-user electric power consumption trends using the load curve during international conflict. We observed that international conflict decreased electric demand by $5.4\%$. This increase is not significant, and therefore we conclude that the international conflict has not greatly affected Korea's electricity demands. This paper provides useful information so as to mon: efficiently perform demand side management.