• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1303-1305
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• 2000

A zero voltage and zero current switching(ZVZCS) fullbridge (FB) PWM converter with secondary auxiliary circuit is proposed. Based on the ZVZCS technique, the ZCS of the lagging-leg switch and ZVS of the leading-leg switch are implemented. And the each secondary side voltage overshoot is decreased by additional secondary auxiliary circuit in this paper. The illustration of its operation principle and the simulation result are presented here.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.230-233
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• 2003

This paper describes the design of torsional oscillation controller in HVDC system using the universal SSR eigenvalue program. The suggested design procedures consist of three steps. Fist step is to identify the characteristics of AC system with torsional modes and HVDC system; then, to determine the control parameters of the suggested torsional oscillation controller (SSRStab) to compensate the phasor lagging due to rectifier controller. Finally, using time-domain simulation program verifies the designed parameters and determine the appropriate gain. The suggested method is simple to tune the parameters and effective to damp the least stable torsional oscillation mode.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.257-262
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• 2003

Now, the population and economical power is deeply concentrated to Seoul-metropolitan region, therefoere the provinces is so lagging behind and the country cannot get balance development. And, like metropolitan region, the more outer the living area of local wide-area city is spreading, the more serious wide-region transportation problems are. But the railroads near wide-area city fun seldom commuter train, so they cannot absorb the transportation demand of wide-area city metropolitan region. To solve above transportation problem, local wide- area cities try to make a subway or a light rail transit. But it is so difficult because the limit of public finance and original small capacity of light rail. In the paper, I propose 'Local city wide-area electric railways' system of the consortium of 'Local wide-city and province transportation union', Korean National Railroad (KNR) and local capital. A 'Local wide-city and province transportation union' operates commuter railways directly using the facilities of KNR, and local capital invests to the stations of above railways system. Therefore the commuter railway system around local wide-city region will be constructed quickly and the stations will be the strong point of local development and investment.

• Proceedings of the Korean Biophysical Society Conference
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• 2001.06a
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• pp.22-22
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• 2001

At the eukaryotic replication fork, discontinuous synthesis of lagging strand DNA gives rise to Okazaki fragments carrying ribonucleotides derived from the primer RNA at their 5' ends. Efficient removal of these ribonucleotides is vital for maintaining genome integrity. In this report we show that the endonucleases Dna2 and Fen1 act sequentially to facilitate the complete removal of the primer RNA.(omitted)

• Proceedings of the KIEE Conference
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• summer
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• pp.896-898
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• 2004

The lagging reactive power should be supplied for the excitation of isolated squirrel-cage induction generators by external circuit. This paper deals with a technique to drive the equations for analysis of the excitation characteristics and performance of an isolated squirrel-cage induction generator from the conventional equivalent circuit of induction machine, transform the equations into d-q coordinates to use vector control technique, and carry out the simulation of an induction generator system with various conditions using MATLAB. The results of the simulation indicate that moderate reactive power can be controlled effectively to maintain constant voltage over a wide range of the rotor speeds and loads.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1632-1642
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• 2014

This paper presents an interleaved resonant converter to reduce the voltage stress of power MOSFETs and achieve high circuit efficiency. Two half-bridge converters are connected in series at high voltage side to limit MOSFETs at $V_{in}/2$ voltage stress. Flying capacitor is used between two series half-bridge converters to balance two input capacitor voltages in each switching cycle. Variable switching frequency scheme is used to control the output voltage. The resonant circuit is operated at the inductive load. Thus, the input current of the resonant circuit is lagging to the fundamental input voltage. Power MOSFETs can be turn on under zero voltage switching. Two resonant circuits are connected in parallel to reduce the current stress of transformer windings and rectifier diodes at low voltage side. Interleaved pulse-width modulation is adopted to decrease the output ripple current. Finally, experiments are presented to demonstrate the performance of the proposed converter.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.213-214
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• 2014

This paper compares two instantaneous reactive power definitions in DFIG wind turbine with a back-to-back three-level neutral-point clamped voltage source converter under unbalanced grid conditions. In general, conventional definition of instantaneous reactive power is obtained by taking an imaginary component of complex power. The other definition of instantaneous reactive power can be developed based on a set of voltages lagging the grid input voltages by 90 degree. A complex quantity referred as a quadrature complex power is defined. Proposed definition of instantaneous reactive power is derived by taking a real component of quadrature complex power. The characteristics of two instantaneous reactive power definitions are compared using the ripple-free stator active power control algorithm in DFIG. Instantaneous reactive power definition based on quadrature complex power has a simpler current reference calculation control block. Ripple of instantaneous active and reactive power has the same magnitude unlike in conventional definition under grid unbalance. Comparison results of two instantaneous reactive power definitions are verified through simulation.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.4
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• pp.383-387
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• 2008

This paper analyzes the operation characteristics of a self excited induction generator with Steinmetz connection. For this analysis, the symmetrical components analysis is used to obtain the related expressions and the excitation capacitance and the magnetizing reactance are determined in turn by the condition of self excitation which includes the input impedance of the generator as viewed across load terminals. Two simultaneous equations of the condition of self excitation itself are solved by using the real and imaginary function in an application software. This method is applied to simulate the operation characteristics when the generator is driven at rated speed and the specified excitation capacitor is connected across the lagging phase. The results show that better operation characteristics except generated frequency are obtained by using relatively large excitation capacitance and resistive load.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.5-8
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• 2009

This paper investigated the qualitative introduction status of domestic major construction company. And that focused on a point of suggestions about CM at Risk introduction. The survey analysis showed that three importan suggestions. First, the biggest obstacles factors to CM at Risk introduction that related laws is lagging amendment. Second, we have to improve the available hands ability in domestic major construction company. And last, we have to do that using uncomplicated design and standard design form. Consequently, environmen analysis for the introduction and example project is urgently required.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.403-406
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• 1995

In general, the reactive power is controlled by amplitude of the output voltage. This paper propose that the multiple voltage source inverter have controllable power factor made by load vary at receive-stage as lagging and leakage control.