• Proceedings of the Computational Structural Engineering Institute Conference
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• 1991.04a
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• pp.68-71
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• 1991

In this study, to make a construction strategy to minimize or protect punchout and steel corrosion in CRCP, the following items have been studied; 1) Review of the structural response characteristics and the current design criteria in CRCP. 2) Evaluation of basic analytical concepts and the limit of application in the current models 3) Some suggestions of performance monitoring in CRCP and evaluation of construction s-trategy with preformed crack induces.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.33 no.3
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• pp.118-124
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• 1984

This paper investigated the characteristics of transient overvoltages on the tower caused by time varying tower footing resistance in the path of lightning stroke current entering earth on transmission lines. The tower with time varying tower footing resistance was simulated and the transient overvoltageson the tower due to lightning stroke current were computer by Nodal Solution Method. From the results, it was found that the determination of the steady state values as a limit of inductive tower footing resistance causes higher transient overvoltages than CFO voltages of insulator strings and V-T characteristics of the insulator strings should be considered for computation of backflashover rate.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.169-171
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• 1994

This paper suggests a SRM control scheme driven by a variable voltage source. This scheme shows that it is unnecessary to introduce a switch to control dc-link voltage and to limit a phase current. And its vary easy to build-up flat-topped phase current which is advantageous to the high torque and efficiency drive of a SRM. Experimental tests are shown to verify this suggestion.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.407-409
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• 1995

CS PWM converter is appropriate for the high power and high precision current control. The input/output filters of the CS PWM converter limit the output DC current range and may destroy the system with filter resonance, and make the system equation more complicated. In this paper, the systematic and simple filter design method which considers not only the harmonic attenuation but the total system performance also is proposed.

• Progress in Superconductivity
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• v.3 no.2
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• pp.229-234
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• 2002

In this paper, we analyzed the fault current performance in a $high-T_{c}$ superconductor(HTS) which was installed on flux-lock reactor with an external magnetic field coil covering the HTS. In this HTS fault current limiter using flux-lock concepts, the initial limiting current level can be controlled by adjusting the inductance of the coils. Furthermore, the current limiting characteristics of $high-T_{c}$ superconducting FCL can be improved by applying the external magnetic field into the $high-T_{c}$ superconductor. This paper discusses current limiting performance according to the inductance of the coil 1 in two cases with ac magnetic field coil or not and suggests the methods to improve the current limiting factor $P_{limit}$, which is defined as the ratio of the limited current $I_{FCL}$ at the current limiting phase to the prospective short -circuit current $I_{PSC}$.TEX> PSC/.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.292-292
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• 2008

The superconducting fault current limiter(SFCL) can be used to limit fault current level in electrical transmission line and power system. Up to now, there are several kinds of SFCL that have proposed and it is expects that they will be applied to appropriated position considering their own properties; initial fault current limiting instant and the current limiting characteristics. In this paper, we investigated the initial fault current limiting instant and the amplitude of initial fault current in the resistive type, the flux-lock type, the flux-coupling type and the transformer type SFCL. Experiment results show that the initial fault current limiting instant and the amplitude of initial fault current of the SFCLs are dependant on the ratio of inductance of primary and secondary coils.

• Journal of Industrial Technology
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• v.25 no.B
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• pp.195-202
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• 2005

The rectifier characteristics and the quality of the input current worsens with the increase of unbalances or harmonics of the supply voltages. Rectifier input current harmonics interfere with proper power system operation, reduce rectifier power factor, and limit the power available from a given source. It is of importance to select appropriately the rectifier's output filter inductance to determine the rectifier input current waveform, the input current harmonics, and the power factor. This paper presents a quantitative analysis of single and three phase rectifier input current harmonics, total harmonic distortion, and power factor as a function of the output filter inductance under balanced and unbalanced conditions. Also, its performance under the supply voltage including harmonics be investigated. These results provide a reference for selecting reasonable rectifier's output filter inductance for given harmonics or power factor criterion.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.198-201
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• 1999

An optimal cooling method for HTS(high Tc superconductor) current leads has been analytically sought to minimize the required refrigerator power. The binary current lead is a series combination of a normal metal conductor at the warmer part and an HTS at the colder part. The lead is cooled by direct contacts with a two-stage cryocooler at the joint and at the cold end. It is clearly proven that there exists unique optimal values for the joint temperature and the current density to minimize the refrigerator power per unit current. the actual power input to the cryocooler in the optimal conditions is compared with its thermodynamic limit, and some significant issues in practical design are presented with a useful graphical method.

• Progress in Superconductivity and Cryogenics
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• v.7 no.1
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• pp.25-31
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• 2005

Since the discovery of the high temperature superconductors many researches have been performed for the practical applications of superconductivity technologies in various fields. As results, significant progress has been achieved. Especially, Superconducting Fault Current Limiter (SFCL) offers an attractive means In limit fault current in power systems. HTS resistive type SFCL is based on the ultra fast transition from the superconducting (non resistive) state to the normal (resistive) state by overstepping the critical current density, In this study, the simulation method of resistive type superconducting fault current limiter using EMTDC is proposed and the developed EMTDC model of SFCL is applied to the modeled power network using the Parameters of real system.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2529-2533
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• 1999

This paper proposes a modified hysteresis current control method based on space vector modulation. The proposed method differs from former works in that it uses effective voltage vectors instead of zero vectors while not significantly increasing the circuit complexity. The circuit uses outer band that is slightly wider than the usual current limit band (inner band) to detect the phase of current command and thereby the region information. The comparator output signals associated with the inner and outer band are used to determine the proper voltage vector that minimizes the current error and number of switching, with simple logic circuitry. The utilization of effective voltage vector is of particular importance when the ac-side emf is relatively large. Both the simulation and experiment show that the proposed method is more effective than the conventional one that uses zero vectors, in reducing the number of switching over a range of ac-side emf variation.