• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.613-615
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• 1996

Harmonic elimination method of using coupling transformer in twelve pulse inverter is presented for high power application. This method is using coupling transformer and PWM(pulse width modulation) switching and voltage source inverter. The object of proposed harmonic elimination method is obtained inverter output of low THD(Total Harmonic Distortion). The simulation results confirm the proposed harmonic elimination method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1056-1059
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• 2001

These days, as dynamic function and special properties to compare traditional material, $Al_20_3$ ceramic use all over the industry. But it is very difficult to process because of high hardness and brittleness. Therefore, in this paper, it was investigated that laser process parameter which can produce appropriate quality of $Al_20_3$ ceramic microhole machining.

• Proceedings of the KWS Conference
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• 2004.05a
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• pp.115-117
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• 2004

Nd:YAG laser welding system was used to manufacture instrumented irradiation fuel. The optimal condition of zircaloy-4 seal tube is charge voltage 180V and pulse per energy 51. We got good welding result in charge voltage 400V, pulse width 7ms, pulse frequency 5 in zircaloy-4 endcap welding.

• Proceedings of the IEEK Conference
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• 2000.06e
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• pp.17-20
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• 2000

Usually, in many applications, high frequency resonant inverters are used, and the PAM(Pulse Amplitude Modulation), PFM(Pulse Frequency Modulation) or PWM(Pulse Width Modulation) techniques are used to control the output power of resonant inverters. In this paper, a new switching scheme is proposed as a PWM control method. With the proposed method, it can be obtained that unity output displacement factor under the variable resonant frequency. The detail algorithm of the proposed PWM switching scheme and its charicteristics are discussed. And the validity of the proposed method is confirmed with the experimental results.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.222-223
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• 2003

As laser pulse width becomes shortened from nanoseconds to femtoseconds, the effects caused by the dispersions of nonlinear optical mediums, such as group velocity mismatch and group velocity dispersion become considerably significant. The group velocity mismatch and group velocity dispersion are the major factors that lead to a decrease of frequency conversion efficiency and pulse spreading for picosecond and femtosecond pulses. (omitted)

• 전기의세계
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• v.20 no.1
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• pp.9-18
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• 1971

The characteristics of optimum control for the second order P.W.M. sampled-data system with linear plants are investigated, with the development of method for finding the cannonical represetations for the initial states, as well as the optimality of modulator output for the P.W.M. system, which contains the electro-mechanical components, by dividing the phase plane into several regions, in which the position of the system in the phase plane are converted into the pulse polarity and pulse width.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.4
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• pp.320-326
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• 2014

In this paper, the new smart dimming algorithm which is mixed with PWM and PAM control method is proposed for reducing the power consumption of LED TV Backlight. The proposed technique is using the curve characteristics of LED forward voltage and current which is proportionally changing LED forward voltage as changing LED forward current. Therefore, each PWM and PAM control method has different LED forward voltage and current in the same brightness condition. The PWM control method adjusts the brightness of LED TV Backlight by only varying the duty ratio of PWM and constantly sustaining the amplitude of LED forward current and voltage. So, the level of LED forward current and voltage in the PWM control method is relatively high and constant regardless of duty ratio of PWM. On the other hand, the PAM control method adjusts the brightness of LED TV Backlight by directly varying the level of LED forward current. So, the level of LED forward current and voltage in the PAM control method is lowered according to the brightness level. For the above-mentioned reason, the PAM control method has the advantage of reducing the total power consumption of LED TV Backlight at the brightness condition of below 100%, compared with PWM control method. By implementing this characteristic to LED driver circuit with control algorithm in MCU, the power consumption of LED TV Backlight can expect to be reduced. The effectiveness of the proposed method, new smart dimming algorithm, CPWAM(=Conditional Pulse Width Amplitude Modulation), has been verified by experimental results.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.186-187
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• 2013

The paper presents a long-pulse modulator for klystron using a high-voltage solid-state switch and a droop compensator. The modulator guarantees the safe of klystron by limiting the amount of energy transferred to klystron in case of arc. The high performance of the modulator is also achieved by the fast transition time, high flatness and average power. The proposed prototype has produced pulses with a flat-top voltage -90[kV], pulse width 1ms and pulse frequency 200[Hz]. The validity of the long-pulse modulator for klystron has been verified by the simulation and experimental works.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.10
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• pp.85-92
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• 1997

For a InGaAsP buried - heterostructrue $1.3\mu\textrm{m}$ LD with fabry-perot cavity structure, the procedures of ultra-short optical pulse genration ar eanalyzed by simulating the rate equations. Investigting the effects of injected current pulse parameters such as bias $J_b$, pulse width $T_d$ and pulse amplitude $J_p$ on the generated optical pulses, we derive the optimum conditions to obtain a single optical pulse with strong peak value. We also observe that the repetition rate of current pulses needs to be restricted under a certain threshold to generate a train of single optical pulses, and that the period doubling phenomenon takes place by increasing the repitition rate.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.1
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• pp.82-86
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• 2012

High-capacity high-voltage pulse generator that can be used for environmental clean-up was developed using transformers. High-voltage pulse is consists of the primary wave and the harmonic wave which are increased as a series circuit using transformers to make pulses. Each transformer has a band-pass characteristics. The output voltage of the pulse width 50[%] was decided. The output voltage of high-voltage pulse generator device was measured as 1.4[kV] (Peak-to-Peak).