• IEIE Transactions on Smart Processing and Computing
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• v.3 no.6
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• pp.425-429
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• 2014

This paper proposes a DC-DC Buck-Converter with DT-CMOS (Dynamic Threshold-voltage MOSFET) Switch. The proposed circuit was evaluated and compared with a CMOS switch by both the circuit and device simulations. The DT-CMOS switch reduced the output ripple and the conduction loss through a low on-resistance. Overall, the proposed circuit showed excellent performance efficiency compared to the converter with conventional CMOS switch. The proposed circuit has switching frequency of 1.2MHz, 3.3V input voltage, 2.5V output voltage, and maximum current of 100mA. In addition, this paper proposes a SCP (Short Circuit Protection) circuit to ensure reliability.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.89-90
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• 2013

Higher power density, higher operational temperature, lower on state resistance and higher switching frequency capabilities of Silicon Carbide (SiC) technology devices compared to Silicon (Si) devices makes it has higher promising market. One of the most developed SiC devices is the power MOSFET. This study tests the SiC MOSFET under short circuit conditions taking into account the effect of gate voltage characteristics. The results will be compared to IGBT and MOSFET Si devices with similar ratings. A tester circuit was designed to perform the short circuit operation.

• Progress in Superconductivity and Cryogenics
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• v.5 no.1
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• pp.56-59
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• 2003

As electric power systems grow to supply the increasing electric power demand short-circuit current tends to increase and impose a severe burden on circuit breakers and power system apparatuses. Thus, all electric equipment in a power system has to he designed to withstand the mechanical and thermal stresses of potential short-circuit currents. Among current limiting devices, Fault Current Limiter (FCL) is expected to reduce the short-circuit current. Especially, Superconducting Fault Current Limiters (SFCL) offer ideal performance: in normal operation the SFCL is in its superconducting state and has negligible impedance, in the event of a fault, the transition into the normal conducting state passively limits the current. The SFCL using high-temperature superconductors offers a positive resolution to controlling fault-current levels on utility distribution and transmission networks. This study contributes to the EMTDC based modeling and simulation method of DC Reactor type SFCL. Single and three phase faults in the utility system with DC reactor type SFCLs have been simulated using EMTDC in order to coordinate with other equipments, and the results are discussed in detail.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.12
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• pp.68-73
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• 2012

In this paper, the fault current limiting characteristics of a flux-lock type superconducting fault current limiter (SFCL) with peak current limiting function were analyzed through its short-circuit tests. The setting condition for the peak current limiting operation was derived from its electrical equivalent circuit, which was dependent on the inductance ratio between the third coil and the first coil. Through the analysis on the short-circuit tests for the flux-lock type SFCLs with the different inductance ratio between the third coil and the first coil, the setting value for the peak current limiting operation of the flux-lock type SFCL with peak current limiting function could be confirmed to be adjusted with the variation of the inductance ratio between the third coil and the first coil.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1783-1785
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• 2001

With the 4-MJ synthetic testing facilities completed, KERI can perform the circuit breaker testing up to 420 kV, 50 kA ratings. The short-line fault test is one of the necessary test items which are required for the circuit breaker, and in order to perform the short-line fault test KERI(Korea Electrotechnology Institute) has used the "new artificial line" which has small dimension and is easy to generate the saw-tooth wave. This paper describes the following items of the new artificial line. -Description of 4-kinds of artificial lines and determination of the circuit parameter of artificial line. -TRV characteristics of saw-tooth waves for each circuit. -KERI's artificial line.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.101-101
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• 2010

Power distribution system requires the transformer with higher capacity than ever, but this ever, but this may be the cause of the increasing of short circuit current in contrast to conventional one when short-circuit accident is occurred. Therefore molded case circuit breaker improved in aspects of interrupting capacity of short circuit current in this system is needed. The arrangement and quality of the material of grids in arc quenching room are also designed optimally by the analysis of arc driving forces.

• Journal of Welding and Joining
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• v.15 no.3
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• pp.47-55
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• 1997

Dynamic characteristics of the short circuit mode are investigated using the Volume of Fluid (VOF) method. When the initial molten drop volume, contact area and wire feed rate are given, rate change of the molten bridge profiles, pressure and velocity distributions are predicted. The electromagnetic force with proper boundary conditions are included in the formulation to consider the effects of welding current. It is found that the molten metal is transferred to the weld pool mainly due to the pressure difference caused by the curvatures in the initial stage, and electromagnetic force becomes dominant factor in the final stage of short circuit transfer. Necking occurs at the contact position between the molten drop and weld pool, and the initial molten drop volume and welding current have significant effects on break-up time.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.695-696
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• 2006

The inrush current of transformer cause saturation effects of recovery voltage for short-circuit power testing. the inrush current depends on the residual flux of the transformer core. when inrush current occurs, it is contains a d.c. component and the high harmonic content of the current are of importance to relay protection of testing circuit. this paper describes of decrease method of inrush current for high power short-circuit testing transformer.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.34-36
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• 1998

In these days the hybrid interrupters are widely used for medium voltage class circuit breakers. In the design of the hybrid interrupter, the shape of the short-circuit ring is one of the most important design parameters. Recently the investigation into the phase difference between arc current and magnetic field due to the shape variation of the short circuit ring has been conducted. In this paper, the results of eddy current analyses in the hybrid interrupter and test result are presented.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5471-5478
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• 2012

In this paper, we propose a new short-circuit detecting method which can detect bad short-circuits, one of bad types occurring in PCB(Printed Circuit Board), by using SURF(Speeded-Up Robust Features) algorithm. The basic procedure in the proposed method sequentially consists of extracting features from both sample and inputted images by SURF, performing perspective transform by feature matching and matching results, extracting check areas of interest, binary coding and extracting short-circuits, and verifying results. The proposed method focuses on the robustness which can detect bad short-circuits even though the position and angle of PCB are not uniform and arbitrarily placed. Experimental results show that our method enables to detect bad short-circuits regardless of the location and angle of PCB placed variously and validate that the proposed method outperforms the conventional methods detecting bad short-circuits manually on the aspect of both the detection rate and time.