• Journal of Power Electronics
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• 제17권6호
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• pp.1422-1432
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• 2017

This paper presents a buck-boost converter-based bipolar pulse generator, which is able to generate bipolar exponential pulses across a resistive load. The concept of the proposed approach depends on operating the involved buck-boost converters in discontinuous current conduction mode with high-voltage gain and enhanced efficiency. A full design of the pulse generator and its passive components is presented to ensure generating the pulses with the desired specifications (rise time, pulse width, and pulse magnitude) for a given load resistance and input dc voltage. In case of moderate pulsed output voltages (i.e. few of kV), one module of the presented bipolar generator can be employed. While in case of high-voltage pulsed output, multi-module version can be employed, where each module is fed from an isolated dc source and their outputs are connected in series. Simulation models for the proposed approach are built to elucidate their performance in case of one-module as well as multi-module based generator. Finally, a scaled-down prototype for one-module of buck-boost converter-based bipolar pulse generator is implemented to validate the proposed concept.

• 한국기계가공학회지
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• 제14권6호
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• pp.129-135
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• 2015

This paper shows significant methods that improve the lifespan of LED modules as well as efficiently using an aluminum heat-sink for LED module in high power. It proposes a method that raises stability and lifespan to protect LED modules and the power unit when the LED module has been used for a long hours at high temperatures. During the research, we applied a method of pulse-width modulation (PWM) in order to prevent the phenomenon that the entire power of a system is turned off and the lifespan is reduced when the LED nodule reacts to the high temperatures. To protect the LED module and SMPS based on high efficiency, a temperature sensor is attached underneath the circuit board and the sensor measures the temperature of circuit board when the LED module is powered on. The electrical power connected to SMPS is controlled by PWM when the temperature of the LED module reaches a particular temperature.

• Current Optics and Photonics
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• 제4권2호
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• pp.127-133
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• 2020

We successfully constructed a passively Q-switched Yb:YAG laser ignitor pumped by a diode laser with low power and long pulse width. To the best of our knowledge, this is the first study to achieve a quasi-MW output power from an optimized Q-switch Yb:YAG laser ignitor by using a pumping diode laser module emitting at under a power of 23 W. The output pulse energy of our optimized laser is 0.98 mJ enclosed in a 1.06 ns pulse width, corresponding to a peak power of 0.92 MW.

• 한국전자파학회논문지
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• 제23권9호
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• pp.1079-1086
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• 2012

본 논문에서는 반도체형 전력 증폭기의 바이어스를 개선하기 위하여 순차 제어 회로와 펄스 폭 가변 회로를 적용한 X-대역 60 W 고효율 전력 증폭 모듈을 설계하였다. 순차 제어 회로는 전력 증폭 모듈을 구성하는 각 증폭단의 GaAs FET의 드레인 전원을 순차적으로 스위칭하도록 회로를 구성하였다. 드레인 바이어스 전원의 펄스 폭을 RF 입력 신호의 펄스 폭보다 넓게 하여 전력 증폭 모듈의 입력 신호가 있을 때만 스위칭 회로를 순차적으로 구동시킴으로써 전력 증폭 모듈의 열화에 따른 출력 신호의 왜곡과 효율을 향상시킬 수 있다. 60 W 전력 증폭 모듈은 고출력 GaAs FET를 이용하여 전치 증폭단, 구동 증폭단과 주전력 증폭단으로 구성하였으며, 주전력 증폭단은 전력결합기를 이용한 평형증폭기 구조로 구현하였다. 설계된 전력 증폭 모듈은 9.2~9.6 GHz에서 듀티사이클 10 %로 동작시켰을 때 50 dB의 전력 이득, 펄스 주기 1 msec, 펄스 폭 100 us, 출력 전력 60 W에서 동작함에 따라 펄스-SSPA 형태로 반도체 펄스 압축 레이더 등에 적용할 수 있다.

• Journal of Electrical Engineering and information Science
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• 제2권4호
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• pp.92-98
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• 1997

This paper presents a new approach to obtaining a reduced-order model for multi-module converters. The proposed approach can be used to derive the reduced-order model for a wide class of multi-module converters including pulse-width-modulated (PWM) converters, soft-switched PWM converters, and resonant converters. The reduced-order model has the structure of a conventional single-module converter while preserving the dynamics of the original multi-module converter. Derivation procedures and the use of the reduced-order model is demonstrated using a three-module boost converter.

• 한국항공운항학회지
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• 제23권1호
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• pp.49-55
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• 2015

This paper deals with dynamic modeling and controller design of a future Korean lunar module planned to be launched 2020's in Korea. For dynamic modeling of the lunar module, we first assume the lunar module as a rigid body. And we derive equations of motion for the lunar module by considering allocation of main thrusters and reaction thrusters. With the equation of motion, we design the controller based on the quaternion. A Pulse Width Pulse Frequency modulator(PWPFM) is selected for generating on/off signal. Finally, we construct a 2-phase descent mode including initial guidance mode, terminal guidance mode. The MATLAB simulation is performed for evaluating the descent ability and final landing velocity. The dynamic modeling and descent simulation of the lunar module in this paper could be applied for developing the future work of the Korean lunar exploration program.

• 한국산업융합학회 논문집
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• 제23권4_2호
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• pp.701-708
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• 2020

In this paper, we analyzed the optical properties of the LED module for dental care, which has the effect of promoting cell regeneration and scar treatment. The LED module is a U-shaped module suitable for the shape of teeth. It is manufactured with an LED module (632 nm) and an LED module (632 nm + 870 nm), analyzes the results of optical properties, sets the irradiation distance, irradiation time, and is effective in healing skin wounds. Evaluation was conducted. It was tested in 6 test groups according to the light irradiation conditions, and light was irradiated to the scar site every other day for 7 days, 1 day and 3 days. As a result, it was confirmed that the effect of scar treatment was the highest when the combined wavelength of 632 nm + 870 nm was irradiated in pulse mode than when the single wavelength was irradiated and the composite wavelength was continuously irradiated. In group C group irradiated with PW Mode: pulse mode (period 36 ms, pulse width 35 ms) using a composite wavelength with LED module (632 nm + 870 nm) than group A without light irradiation, the length of scar reduction was 19 %, the area of the scar was further reduced by 10%, and it was confirmed that it is effective in treating scars in the wound area.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.215-217
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• 2001

This paper describes an all solid-state switch pulse generator for various applications where square pulse voltage is required. The pulse generator produces various voltage pulses: voltage $5{\sim}100kV$. current $10{\sim}200A$, pulse width $1{\sim}10{\mu}sec$, repetition rate up to 500Hz. The output power is the combination of these parameters up to 10kW. It consists of a DC-DC converter and several pulse generating modules which are connected in series to obtain higher pulse voltage. Each module contains semiconductor switches (IGBT's), energy storage capacitors and control units to trigger switches. The structure and operational principle are described and the protection circuit for reliable operation is suggested. Experimental results show that the pulse generator can be used for applications with nonlinear loads.

• 한국군사과학기술학회지
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• 제13권6호
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• pp.1071-1079
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• 2010

This paper describes the design and fabrication of a high-efficiency GaN HEMT(Gallium Nitride High-electron Mobility Transistor) Pallet power amplifier module for S-band phased array radar applications. Pallet amplifier module has a series 2-cascaded power amplifier and the final amplification-stage consists of balanced GaN HEMT transistor. In order to achieve high efficiency characteristic of pallet power amplifier module, all amplifiers are designed to the switching-mode amplifier. We performed with various PRF(Pulse Repetition Frequency) of 1, 10, 100 and 1000Hz at a fixed pulse width of $100{\mu}s$. In the experimental results, the output power, gain, and drain efficiency(${\eta}_{total}$) of the Pallet power amplifier module are 300W, 33dB, and 51% at saturated output power of 2.9GHz, respectively.

• 한국산학기술학회논문지
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• 제8권6호
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• pp.1355-1362
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• 2007

본 논문에서는 태양광 발전의 효율을 높이기 위하여 센서와 마이크로프로세서를 이용한 태양광 위치추적 장치를 설계하여 고정 방식의 태양광 발전과 위치 추적 방식의 태양광 발전에 대하여 비교해 보았으며, 태양전지에 대한 특성 해석과 수학적 모델링을 통한 시뮬레이션을 행하여 태양전지 특성 사양과 비교해 보았다. 또한 전력변환 시스템을 Boost 컨버터와 전압형 인버터로 구성하여 각각에 대하여 실험하였으며, Boost 컨버터 제어에서 최대 전력점 추적을 위해 일정전압 제어법을 사용하였다. 인버터의 제어에서는 SPWM(Sinusoidal Pulse Width Modulation) 제어법을 사용하여 실험하여 좋은 결과를 나타내었다.