• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.1
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• pp.105-110
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• 1999

This paper describes the inverter driven air-condetioner with power factor correction (PFC) circuit. By adopting PFC in the rectifier, we can reduce harmonic injection into power line, improve the efficiency and lower the total system cost compared to conventional inverter only. Also, system performance is improved by stabilizing the output voltage of PFC. In this paper, detailed design procedures for PFC are given, and the several merits with PFC are verified through the simulation and experiment.

• Journal of Power Electronics
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• v.9 no.6
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• pp.903-910
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• 2009

In this paper, a digital average current mode control using diode current sensing technique is proposed. Although the conventional inductor current sensing technique is widely used, the sensed signal of the current is negative. As a result, it requires an additional circuit to be applied to general digital controller ICs. The proposed diode current sensing method not only minimizes the peripheral circuit around the digital IC but also consumes less power to sense current information than the inductor current sensing method. The feasibility of the proposed technique is verified by experiments using a 500W power factor correction (PFC) boost rectifier.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.2
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• pp.122-129
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• 2011

In this paper, a new power factor correction circuit(PFC) based on a soft-switched boost scheme is proposed. Except for some soft-switching transition intervals, it operates exactly like the conventional boost scheme. Thus the desirable features of both high efficiency and easy control can be obtained. The design guidelines are suggested to achieve high efficiency. To verify the superior performance of the proposed circuit, experiment and simulation is carried out.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.787-790
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• 2004

In this paper, a novel control scheme compensating for source voltage unbalance and current harmonics and power factor correction in unified active power filter systems combined with shunt passive filters is proposed, where no low/high-pass filter are used in deriving the reference voltage for compensation. Using digital all-pass filters, the phase angle and the reference voltages compensating for harmonic current and unbalanced voltage are derived from the positive sequence component of the unbalanced voltage. The amplitude of d-axis current in a series filter is controlled as zero for power factor correction. The validity of the proposed control scheme has been verified by experimental results.

• Journal of Advanced Marine Engineering and Technology
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• v.21 no.2
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• pp.178-185
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• 1997

According to the wide - spread use of rectifier in electronic equipments, such problems as electronic components failures or equipment disorders have been occurred due to current harmonics. To overcome these problems, power factor correction circuits employing boost converter have been used. The high switching stress of boost converter can be reduced by snubber circuit. Recently, research activities in snubber circuits have been directed to energy recovery snubber for improving the efficiency of power converter. In this study, a new passive snubber circuit which can recover trapped snubber energy without added control is proposed for boost converter. The control of boost converter with proposed snubber is the same as the conventional one. In addition, the energy recovery circuit can be implemented with a few passive components. The circuit operation is confirmed through simulation.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.1
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• pp.28-35
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• 2005

Fuel injection rate of an injector is affected by various injection conditions such as injection duration, fuel temperature, injection pressure, and voltage in LPG liquid injection systems for either a port-fuel-injection(PFI) or a direct injection(DI) in a cylinder. Even fuel injection conditions are changed, the air-fuel ratio should be accurately controlled to educe exhaust emissions. In this study, correction factor for the fuel injection rate of an injector is derived from the density ratio and the pressure difference ratio. A voltage correction factor is researched from injection test results on an LPG liquid injection engine. A compensation method of the fuel injection rate is proposed for a fuel injection control system. The experimental results for the LPG liquid injection system in a SI-engine show that this system works well on experimental range of engine speed and load conditions. And the fuel injection rate is accurately controlled by the proposed compensation method.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.270-272
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• 2003

Switching power supplies are widely used in many industrial fields. Power factor correction(PFC) circuits have tendency to be applied in new power supply designs. The input active power factor correction(APFC) circuits can be implemented using either the two-stage approach or the single-stage approach. The single-stage PFC circuit has advantage to reduce the number of components by eliminating a need for the PFC switch and control circuit. However, unlike in the two-stage approach, the do voltage on the energy storage capacitor in a single-stage PFC circuit is not well regulated. As a result. in universal line application($90{\sim}265Vac$), the storage capacitor voltage varies with the load and line variation. In this paper, the performance of output voltage regulation and transient response are clarified here. The validity of designed boost PFC circuit is confirmed by MATLAB simulation and experimental results of 2 [kW] prototype converter.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.540-545
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• 1997

An analytical and experimental investigation has been performed on the heated length-to-diameter effect on critical heat flux for fixed exit conditions. A L/D correction factor is developed by applying artificial neural network and conventional regression techniques to the KAIST CHF data base. In addition, experiment is being performed to validate the developed L/D correction factor with independent data. Assessment shows that the developed correction factor is promising for practical applications.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.7
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• pp.475-482
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• 2000

This paper presents a novel power-factor correction method using customer STATCOM which generally improves the power quality of electric customers. Customer STATCOM detects the reactive currents of a induction motor(IM) and so injects compensation currents which is in 180$^{\circ}$ phase with load currents that the reactive power of IM is compensated. In particular, the paper proposes the general compensation current references in the synchronous coordinate system and makes converter output voltages using space-vector PWM. The compensation effect of customer STATCOM is confirmed through the simulation according to the operation condition of an induction motor (at no load and full load).

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.233-235
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• 2001

On the active filter converter for power factor correction is used inverter for a air-conditioner's power supply to meet IEC standard In the active filter topology for power factor correction, extra switch only control the input current indirectly to satisfied with the IEC standard for reducing the cost and size. In this paper, by dividing the input current into two different modes, the current conduction period can be widened and harmonics can largely be canceled between the two modes. Hence, the harmonics characteristics can be significantly improved, whereby the lower order harmonics, such as the fifth and seventh orders, are much reduced. The results are confirmed by theoretical and experimental implementations.