• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.255-258
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• 1996

A new low conduction loss, low cost zero-voltage-transition power factor correction circuit(PFC) is presented. Conventional PFC which consists of a bridge diode and a boost converter(one switch) always has three semiconductor conduction drops. Two switch type PFCs reduces conduction loss by reducing one conduction drop but the cost is increased because of increased number of active switches. The proposed PFC reduces conduction loss with one switch, which allows low cost. Conduction loss improvement is a little bit less than that of two switch type, but very close up. Operation and features are comparatively illustrated and verified by simulation and experimental results of 1 kW laboratory prototype.

• Journal of the Korean Society of Combustion
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• v.12 no.2
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• pp.34-41
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• 2007

The dynamic behaviors of counterflow non-premixed flame have been investigated experimentally to study effects of heat losses and Lewis number on edge flame oscillation, which result from the advancing and retreating edge flame motion of outer flame edge at low strain rate flame. For low strain rate flame, lateral conduction heat loss in addition to radiation heat loss could be more remarkable than the others. Oscillatory instabilities appear at fuel Lewis number greater than unity. But excessive lateral conduction heat loss causes edge flame instability even at fuel Lewis number less than unity. The excessive heat loss caused by the smaller burner diameter in which the flame length is an indicator of lateral conduction heat loss extends the region of flame oscillation and accelerates oscillatory instability in comparison to the previous study with the burner diameter of 26mm. Extinction behaviors quite different from the previous study are also addressed.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.145-152
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• 2007

The dynamic behaviors of counterflow non-premixed flame have been investigated experimentally to study effects of heat losses on edge flame oscillation, which result from the advancing and retreating edge flame motion of outer flame edge at low strain rate flame. For low strain rate flame, lateral conduction heat loss in addition to radiation heat loss could be more remarkable than the others. Oscillatory instabilities appear at fuel Lewis number greater than unity. But excessive lateral conduction heat loss causes edge flame instability even at fuel Lewis number less than unity. The dramatic change of burner diameters in which flame length is an indicator of lateral conduction heat loss was applied to examine the onset condition of edge flame oscillation and flame oscillation modes. Especially, extinction behaviors quite different from the previous study were observed.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2568-2571
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• 1999

Recently, new trend in telecommunication device is to apply low voltage, about 3.3V-1.5V. However, it is undesirable in view of high efficiency and power desity which is the most important requirement in the distributed power system. Rectification loss in the output stage in on-board converter for distributed power system are constrained to obtain high efficience at low output voltage power suppies. This paper is investigated conduction power loss in synchronouss rectifier with a parallel -connected Schottky Barrier Diode(SBD). Conduction losses are calculated for both MOSFET and SBD respectively. The SBD conduction power loss dissipates more than the MOSFET rectifier conduction power loss.

• Journal of Power Electronics
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• v.7 no.1
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• pp.55-63
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• 2007

This paper proposes a simple unity power factor zero-voltage-transition (ZVT) pulse-width-modulated (PWM) single-phase rectifier, which features reduced switching and conduction losses. The switching loss reduction is achieved by a simple auxiliary commutation circuit, and the conduction loss reduction is achieved by employing a single-stage converter, rather than a typical double-stage converter comprising of a front-end rectifier and a boost rectifier. Furthermore, thanks to good features such as a simple PWM control at constant frequency, low switch stress, low Var rating of commutation circuits, and simple power circuit structure, it is suitable for high power applications. The principles of operation are explained in detail, and a major characteristics analysis and the experimental results of the new converter are also included in this paper.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.2
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• pp.173-183
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• 2014

In this paper, an analysis of power losses for the three-level T-type and neutral-point clamped (NPC) PWM inverters is presented, in which the conduction and switching losses of semiconductor devices of the inverters are taken into account. In the inverter operation, the conduction loss depends on the modulation index (MI) and power factor (PF), whereas the switching loss depends on the switching frequency. Power losses for the T-type and NPC inverters are analyzed and calculated at the different operating points of MI, PF and the switching frequency, in which the four different models of semiconductor devices are adopted. In the case of lower MI, the NPC-type is more efficient than the T-type, and vice versa. The validity of the power loss analysis has been verified by the simulation results.

• Proceedings of the KIPE Conference
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• 2001.12a
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• pp.79-82
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• 2001

New electronic ballast for metal halide laws is proposed New ballast has higher efficiency than that of conventional ballast. Proposed 2 stage ballast uses low arm switch as synchronous rectifier mitch. Switch-on voltage drop is smaller than that of diode in small current(<1.5A). High arm switch is turned on in zero voltage in proposed ballast. So conduction loss and switching loss are reduced Index word - synchronous rectifier mitch, toro voltage switching, conduction loss, switching loss.

• Journal of Industrial Technology
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• v.24 no.A
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• pp.119-126
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• 2004

BLDC Motor is one of the widely utilizable motors in servo system. The accurate calculation of the power loss for the IGBT and Inverse diode with Bipolar and Unipolar switching modes the driving modes is important for the design of drives for their heat treatment. If it were not for temperature-sensors in devices, it is difficult to get direct power loss, so. Power losses may be modeled by computer modeling to obtain the Calculation of the Power loss for Inverter in BLDC Motor with switching modes which is presented in this paper. The computer modeling is carried out by Matlab simulation. The power loss consists of conduction losses Conduction losses are the source of occurrence due to The IGBT and Inverse diode currents. Switching losses are the source of occurrence due to switching on/off in the devices, and gives the dominant influence to the loss. As a result, the unipolar I mode is best in reducing the heat losses.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.663-664
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• 2012

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.391-393
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• 2008

A modified boost converter with magnetic coupling is presented to reduce the reverse recovery loss while maintaining low conduction loss of the rectifiers. By utilizing a coupled inductor and a set of diodes, the current passing the boost rectifier is transferred to an auxiliary loop before turn-off, allowing low di/dt for reduced recovery loss. Moreover, the boost inductor is brought inside the bridge rectifier to reduce conduction loss by decreasing the number of conducting diodes during switch turn-off. Experimental results of a 500W prototype are provided to verify the increase in efficiency and validity of the proposed converter.