• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1136-1141
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• 1992

This paper proposes a control technique to obtain high frequency quasi sinusoidal DC-Link waveform permitting zero-voltage-switching(ZVS). This operation results in reduction of commutation stress and switching losses in the power devices because they cause no switching loss in principle. But in existing control methods, the resonant capacitor voltage is not frequently made of zero-cross oscillation. We propose an optimum control stratege which can sustain oscillation and keep the capacitor voltage at an allowable level. Some experimental results are included to confirm the validity of the analytical results.

• Proceedings of the KIEE Conference
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• 2007.11c
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• pp.187-190
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• 2007

To improve the power factor and reduce the harmonic contents of the system, the design of tunned filters for six-pulse thyrister converter which is used by electrolyzer system is discussed in this paper. Tunned filters are added to high-power rectifiers to keep the line current distortion within allowable limits and to improve the rectifier power factor. For electrolyzer system, the design procedure of tunned filters of AC 14.4kV power system are proposed by dynamic simulation. It is shown that these harmonic filters can meet most operational requirments. The the proposed design procedure is verified with the simulation and experimental results.

• Steel and Composite Structures
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• v.5 no.4
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• pp.259-269
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• 2005

Many slab-on-girder bridges around the world are being assessed because they are approaching the end of their anticipated design lives or codes are permitting higher allowable loads. Current analytical techniques assume that the concrete and steel components act independently, typically requiring full-scale load testing to more accurately predict the remaining strength or endurance of the structure. However, many of the load tests carried out on these types of bridges would be unnecessary if the degree of interaction resulting from friction at the steel-concrete interface could be adequately modeled. Experimental testing confirmed that interface friction has a negligible effect on the flexural capacity of a slab-on-girder beam however, it also showed that interface friction is significant under serviceability loading. This has led to the development of an improved analytical technique which is presented in this paper and referred to as the slab-on-girder mixed analysis service load assessment approach.

• Proceedings of the KIEE Conference
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• 2006.11a
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• pp.405-407
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• 2006

The power system analysis based on the accurate impedance of the individual underground cable, which is the inter connected to a large power system, is required. A study on calculation method of impedance allowable current for underground cables. furthermore, various methods of bonding and earthing the sheath have been used for the purpose of eliminating or reducing the sheath losses. the effectes of bonding and earthing must be includied in impedances. therefore, the subject of predicting thermal performance of soil and cable systems has been received increasing attension. for these problems, this paper describes a general formulation of impedance that is based on the effect of crossbonding and earthing of the sheath on the 66kV, 132kV and 220kV underground cable systems. also the work is presented, for calculating the temperature rise of power cable and soil.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.767-772
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• 2004

A dynamic simulation program of a catenary-pantograph system including tunnel section and transient section is developed in this study. The simulation program can accommodate for the pantograph of two panheads and three d.o.f model. Using the developed program, the dynamic characteristics with a SCHUNK'S WBL 85-PANTOGRAPH is analyzed at the conventional TAEBAEK line and its tunnel section when the catenary system is supported by a tunnel bracket. The simulation results show that the variation of contact force and uplift displacement is allowable in general section and the entrance and exit of a tunnel, but the uplift displacement and the separation ratio within tunnel section is difficult to allow.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.125-128
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• 1999

In this paper, we propose a QoS-sensitive admission threshold method for the transmission of the non-real tine data packet such that the quality of services for both voice and data traffics are maintained to a required level. By detecting the active voice traffic during the current time slot, the non-real-time data packets are transmitted up to an admission threshold level during the next time slot. We found out that the optimum admission threshold is four voice traffic resources lower from the maximum allowable threshold to maintain the outage probability within 1% when the connected voice users are 15.

• Progress in Superconductivity and Cryogenics
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• v.14 no.2
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• pp.8-11
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• 2012

In order to recognize the allowable bending diameter in coils, the strain as function of diameters is evaluated. The irreversible strain limits of $I_c$ in the easy and hard bending modes were measured. Strains were calculated at the coating film in the easy bending and at outer edge or inner edge in the hard bending of the CC tape, respectively. The tape geometry subjected to bending procedures is considered from the current industrial spool winding operation. Through the linear superposition of strain induced in different bending modes regarding the expressions, the appropriate design for critical bending diameter is suggested. Results proved that the existence of buckling resulting from bending in hard direction when applied strain exceeded 0.6% is possible. The depicted results showed that the strain limit as a viable parameter should be considered for future purposes.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.15-17
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• 2004

Most of LV customer has been composed the 3-phase four wire system distribution system which is supplying simultaneously at the 1-phase & 3-phase load. In this system, the composition of the power apparatus system is simple rather than conventional separation mode of the 1-phase & 3-phase, But due to uneven load unbalance or unclean power quality, various kinds such as derating or power losses become an issue. In this paper, we measured and analyzed voltage and current waveform in the field, compared with internationally allowable voltage unbalance limits.

• Congress of the korean instutite of fire investigation
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• 2010.12a
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• pp.91-119
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• 2010

There is an increasing number of car fires along with the increasing numbers of cars. The purpose of this study was to verify the possibility of fires caused by car tuning, which is one of the causes of car fires. The result showed that the possibility of car fires was increased by car tuning including replacement of headlights, excess of allowable current of wires or fuses by using multi cigar jacks, wire damage, earth fault, and vulnerability of wires and cables (sold in auto parts stores) to heat.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.446-447
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• 2008

In this paper, a calculation method of the short-time emergency by considering a initial load level and overload time is presented. short-time emergency analyze transient thermal rating and Long-time emergency analyze steady-state thermal rating. Using the suggested method in the paper, increasing the short-term allowable current.