• Journal of Advanced Marine Engineering and Technology
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• 제21권5호
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• pp.591-597
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• 1997

Instantaneous velocity distribution within coaxial circular pipe for measurement velocity of high speed is acquired simultaneously by applying the 2-dimensional PTV system consisting of a pulse generator(AOM:Acousto-Optical Modulator), a continuous-output laser and a PC image grabber together with experimental apparatus. The basic mechanism of AOM and vector identification method and performance-related image processing techniques are discussed. Representative measuring regions $90{\times}90$mm are selected and instantaneous vectors are represented and fully developed turbulent flow of maximum velocity up to about 1.0 m/sec is obtained.

• 한국자동차공학회논문집
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• 제9권5호
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• pp.140-147
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• 2001

The solenoid valve in ABS hydraulics, modulator is a two directional on-off valve and is controlled by around 100Hz high speed pulse width modulation. When the inlet valve is switched from open state to closed state, there are braking force degration, noise and vibration due to pressure surge phenomena in the hydraulic line and wheel cylinder. In this study, identifies pressure surge phenomenon in the braking process of a ABS, and investigates the way to reduce the phenomenon. For the purpose theoretical analysis on the pressure surge in the closed state hydraulic line, characteristic curve method based on wave equation was utilized. During this analysis, we could find pressure surge characteristics change due to hydraulic line change and PWM control conditions. In conclusion, by using the results of this study for the pressure surge prediction and reduction method, we could expect braking performance enhancement in Anti-Lock Braking System.

• Journal of the Optical Society of Korea
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• 제3권2호
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• pp.51-54
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• 1999

A Nd:YLF laser has been actively mode-locked at the third-order harmonic cavity frequency using a lithium niobate phase modulator. Self-oscillating pulses of 14 ps duration, 1 GHz repetition rate, and 10mV average power at 1053 nm wavelength have been obtained. A 1GHz rf signal to drive a phase modulator was obtained by using 1GHz pulse train without rf synthesizer as a driver of an active mode locker.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.123-125
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• 2007

포항가속기연구소가 추진 중인 제4세대 방사광가속기에는 100 PPM급의 클라이스트론 펄스전압 안정도가 요구된다. 이러한 안정도는 PFN(pulse forming network)에 충전되는 전압을 얼마나 정밀하게 제어하는가에 따라서 결정된다. PFN의 최종운전 전압은 deQing circuit에 triggering되는 시점에 따라서 결정된다. DeQing trigger system은 PFN의 충전전압과 기준전압을 비교하여 충전전압이 기준전압보다 커지는 시점에서 charging choke(충전 쵸크)의 2차에 구성된 deQing 회로의 SCR를 트리거 시켜서 충전 쵸크 1차와 2차의 권선비율이 25:1인 충전 쵸크의 2차를 단락시켜 1차에 흐르는 전류를 2차로 빼주어서 PFN 커패시터에 더 이상 충전되지 않게 하는 구조로 되어있다. DeQing circuit에 triggering되는 시점을 정밀하게 제어하기 위하여 PFN 충전전압을 미분하여 그 출력전압에 비례하여 트리거 출력을 지연시키는 기능과 analog 신호를 digital 신호로 변환하는 기능을 사용하였다. 이 논문에서는 deQing 시스템에 관련된 회로 및 시험결과에 대하여 설명하고자 한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 추계학술대회
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• pp.101-103
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• 2018

This paper describes -40kV high voltage solid state pulse power modulator (SSPPM) for driving a magnetron, which is used as a RF power source of LINAC for cancer treatment systems. In case of the medical LINAC, small size and light weight are required. The SSPPM is 92 liters in size and weighs 50 kg. In this paper, S-band 2.6 MW magnetron load experiment is conducted and impedance matching was applied to obtain a smooth output current. Finally, the experimental results is discussed and the reliability of SSPPM is verified.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1550-1551
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• 2006

An L-band linear accelerator system for e-beam sterilization is under design for bio-technology application. The klystron-modulator system as RF microwave source has an important role as major components to offer the system reliability for long time steady state operation. A PFN line type pulse generator with a peak power of 71.5-MW, $7{\mu}s$, 285 pps is required to drive a high-power klystron. The high power pulse transformer has a function of transferring pulse energy from a pulsed power source to a high power load. The pulse transformer producing a pulse with a peak voltage of 275 kV is required to produce 30-MW peak and 60 kW average RF output power at the frequency of 1.3-GHz. We have designed the high power pulse transformer with 1:13 step-up ratio. The peak and average power capability is 71.5-MW (275 kV, 260 A at load side with $7{\mu}s$ pulse width) and 130 kW, respectively. In this paper, we present a system overview and initial design results of the high power pulse transformer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1079-1081
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• 2007

An L-band Linear Accelerator System for E-beam sterilization is under construction for bio-technology application. The klystron-modulator system as an RF microwave source has an important role as major components to offer the system reliability for long time steady-state operations. A PFN line type pulse generator with a peak power of 71.5-MW, $7\;{\mu}s$, 285 pps is required to drive a high-power klystron. The high power pulse transformer has a function of transferring pulse energy from a pulsed power source to a high power load. The pulse transformer producing a pulse with a peak voltage of 275 kV is required to produce 30-MW peak and 60 kW average RF output power at the frequency of 1.3-GHz. We have designed the high power pulse transformer with 1:13 step-up ratio. The peak and average power capability is 71.5-MW (275 kV, 260 A at load side with $7\;{\mu}s$ pulse width) and 130 kW, respectively. In this paper, we present measurements and its analysis on the design parameters, and an initial test result as well as a design concept on the high-power pulse transformer.

• Journal of the Optical Society of Korea
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• 제5권1호
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• pp.25-28
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• 2001

By using an XPM (Cross Phase Modulation) wavelength converter, an all-optical AND gate, which is one of six fundamental logic gates, has been demonstrated. The wavelengths for probe and pump signals are 1553.8 and 1545 nm, respectively. First, characteristics of the XPM wavelength converter have been studied. When both probe and pump signals are driven by high power, the output power of the XPM wavelength is high. Based on this fact and the experiment, the all-optical AND gate has been porved. Probe and pump signals are transformed to pulse signals by using Mach-Zehnder modulator, which is induced by a pulse generator. Square pulse signals that are similar to the format of NRZ signals have been generated. By coupling two pulse signals into the XPM wavelength converter, AND characteristics in substantiated.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 16-17 Oct. 1987
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• pp.312-316
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• 1987

A simple hybrid circuit to control the two-phase AC motor of the nut-runners which employ the tightening torque control system is described in this paper. The circuit has emphasis on the low-cost implementation. The circuit constitutes of the V/F converter using a timer IC, the pulse width modulator using the fastening torque signal and the two-phase logic sequencer.

• 한국광학회지
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• 제34권4호
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• pp.151-156
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• 2023

파장당 200 Gb/s급 신호를 전송하는 고속 근거리 광통신 시스템을 비용 효율적으로 구축하기 위한 방안으로서 캐리어 억제 펄스 기반의 2채널 광학적 시분할 다중화 시스템을 제안한다. 캐리어 억제 펄스는 널 바이어스가 인가된 마하 젠더 변조기로 생성되며, 이는 시분할 다중화 신호를 색분산에 강인하게 만든다. 송신부에서는 캐리어 억제 펄스를 둘로 분기하고, 각각을 100 Gb/s의 4레벨 진폭 변조 신호로 변조한 후, 광학적 시분할 다중화를 통해 200 Gb/s의 신호를 생성한다. 다중화된 광 신호는 광섬유로 전송된 후, 반도체 광 증폭기로 증폭되며, 한 개의 광 검출기로 검출된다. 증폭기에 의해 발생한 잡음은 광학 필터로 제거된다. 시분할 다중화 과정에서 발생하는 누화는 다중 입력-다중 출력 이퀄라이저로 보상한다. 본 연구에서는 200 Gb/s의 고속 신호를 40 ps/nm의 색분산을 갖는 광섬유로 전송하여도 3.8×10^-3 이하의 비트 오율을 확보할 수 있음을 시뮬레이션으로 확인하였다.