• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.342-344
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• 1994

In this paper, the dynamic characteristics of the existing filter is analyzed to obtain a sinewave current from full bridge inverter with low pass LC filter. The Chevshev's filter, which is most typical low pass filter, is adopted for this investigation and driven controller of full bridge inverter used EV8097BH one-chi p controller.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.4
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• pp.538-550
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• 1998

The variable frequency and variable voltage AC source made by a conventional inverter which is composed of power semi-conductors includes much noises in sine wave due to high frequency switching of DC source. In this paper the 3rd low pass LC filter for a variable speed 3 phase induction motor driven by a full bridge inverter is introduced to solve the EMI problem by serious noise current. The utility of a modified 3rd order Butterworth LC filter is confirmed through FFT analysis of sine waves and noiseless ACsource can be obtained by the proposed LC filter. The speed of a 3 phase induction motor driven by a full bridge inverter with a LC filter is satisfactorily controlled by a digital PID controller under the condition of stepwise load and setpoint changes.

• Journal of the Korean Society for Railway
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• v.7 no.3
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• pp.173-179
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• 2004

This paper describes a low-cost single-phase active power filter, which consists of a half-bridge PWM inverter with a simple control circuit. In order to verify the performance of proposed active power filter, many computer simulations with EMTP codes and experimental works with a hardware prototype were done. Both results confirm that the proposed active power filter shows excellent performance to eliminate the harmonics generated in the single-phase non-linear load. The active power filter has advantage of low implementation cost and compact size, using a half-bridge inverter and a simple control circuit with only one current sensor. So, it can be fabricated as a plug-in type. This paper shows the necessity and a good possibility to apply such advantage to the electric railway system.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.5
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• pp.364-371
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• 2007

This paper deals with filter design for utility-interactive voltage-sourced PWM inverters built by single-phase half-bridge topology. By analyzing the relation between utility voltage and the ac output voltage of single-phase half-bridge inverters, the instantaneous voltage applied on the filter inductor is deduced qualitatively and quantitatively. Moreover, switching ripple current through the filter inductor is calculated from the filter inductor voltage. Based on the above mentioned analysis, filter design method is proposed by evaluating the percentage of the switching ripple current against the rated fundamental current. Proposed filter design method is verified by simulation and experiment.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.4
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• pp.346-353
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• 2007

This paper deals with filter design for utility-interactive voltage-sourced PWM inverters built by single-phase full-bridge topology By analyzing the relation between utility voltage and the ac output voltage of single-phase half-bridge inverters, the instantaneous voltage applied on the filter inductor is deduced qualitatively and quantitatively. Moreover, switching ripple current through the filter inductor is calculated from the filter inductor voltage. Based on the above mentioned analysis, filter design method is proposed by evaluating the percentage of the switching ripple current against the rated fundamental current. Proposed filter design method is verified by simulation and experiment.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.5
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• pp.99-111
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• 1993

In this paper, the current waveform and dynamic characteristics of the proposed system which is composed of a full bridge inverter and low pass LC filter is investigated through the results of computer simulation and experiment to find out the good performance of variable speed AC motor. By the experiment results, it is confirmed that the load current of pseudo sine waves is to be got by the proposed low pass LC filter and the speed of single phase AC motor driven by a full bridge inverter can be smoothly controlled by use of digital PID controller.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1313-1315
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• 2002

This paper proposes an inverter for the grid-connected photovoltaic system based on the transformer-less inverter. This system consists of a high frequency inverter bridge, high frequency transformer, diode bridge rectifiers, a DC filter, a low frequency inverter bridge, and an AD filter. The high frequency inverter bridge switching at 20kHz is used to generate bipolar PWM pulse, which is subsequently rectified by diode bridge rectifiers to result in a full-wave rectified sine wave. Finally, it is unfolded by a low frequency inverter bridge to result in a 60Hz sine wave power output. In this paper, the control algorithm for synchronous current feedback control method and a maximum power point tracking (MPPT) method using DSP are described. And, the simulation and experimental results are shown to verify the validity of the proposed system.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.598-602
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• 2006

Local scour is associate with particular local types of vortex around bridge piers. This paper is method of protection local scour for the existing Busan City subway 3 Line bridge piers and Gupo large bridge piers. In order to take design of protection of local scour this bridge piers, We calculate the local scour hole of depth , scour width, riprap construction , filter construction by formulas. We had experimental hydraulic model test for this bridge piers in order to take proof for the calculation of local scour. We knew that the vortex intensifies the local flow velocities and acts to erode sediment from the scour hole and transport it downstream. As the result of hydraulic model test, we could suggest three types method of protection local scour this bridges. We knew that FHWA HEC-18(Richardson et al. 2001: Modified CSU) Formula is useful to checking calculation as application of field. One is pier protection using the sheet piles and riprap, the others are pier protection using the riprap with filter and to make renew Wall-caisson. The best method of protection for the existing Busan City subway 3 Line bridge piers and Gupo large bridge piers is pier protection using the sheet piles and riprap.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.82-83
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• 2008

In the cases of high speed railway bridge, dynamic behavior analysis is important because of high passing velocity and moving load at the regular intervals, and the damping ratio is a major element in dynamic behavior analysis. In this paper, damping ratios were estimated by two methods and vibration type sections, and relationship between estimated damping ratio and representative value of bridge vibration. At the results, estimated damping ratio using all time of vibration were more stable then using only free vibration section. And in the case of using extended Kalman filter, estimated damping ratio were trend of growth by growth of representative value of bridge vibration. At last, it was shown that study about reliabilities of estimated damping ratios were need.

• Journal of Advanced Marine Engineering and Technology
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• v.19 no.4
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• pp.79-91
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• 1995

Recently, the AC motor which has a simple structure and needs less maintenance has become to be used frequently as a servomotor for position control in the automatic control field. This paper concerns with a method to improve the current and power waveforms of an AC motor, and the current waveforms and 3$\phi$ power waveforms are analyzed by FFT under verious running conditions. The system is composed of a digital bridge inverter, low pass LC filter, and 3$\phi$ AC motor. Through the computer simulations and experiments, it is confirmed that current waveforms and $\phi$ power waveforms con by improved by utilizing the high order low pass LC filter than that of lower order.