• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(5)
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• pp.215-218
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• 2001

A pulsed Nd:YAG laser is used widely for materials processing and medical instrument. It's very important to control the laser energy density in those fields using a pulsed Nd:YAG laser. A pulse repetition rate and a pulse width are regarded as the most dominant factors to control the energy density of laser beam. In this paper, the alternating charge and discharge system was designed to adjust a pulse repetition rate. This system is controlled by microprocessor and allows to frequence an expensive condenser for high frequency to cheap one for low frequency. In addtion, The microcontroller monitors the flow of cooling water, short circuit, and miss firing and so on. We designed Nd:YAG laser firmware with smart microcontroller, and want to explain general matters about the firmware from now.

• 한국광학회지
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• 제3권1호
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• pp.37-42
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• 1992

공진기 내에서 종자펄스를 여러번 왕복시키며 증폭시키는 재생식 증폭기의 설계 및 동작톡성에 대하여 연구하였다. 기계적, 열적 요동에 대하여 안정된 작동을 하도록 Nd:YLF를 레이저 매질로 사용하고, 광학 부품에 미치는 에너지 밀도를 최소화할 수 있도록 오목거울과 볼록거울로 구성된 증폭기 공진기를 설계, 제작하였다. 종자펄스로는 펄스 폭 40ps, 에너지 100pJ, 파장 1,053.$\mu$m인 Nd:YLF 레이저 펄스를 사용하여 재생식 증폭기로 최대 반복률 3.5kHz에서 1mJ의 안정된 펄스를 얻었으며, 최대 출력은 5mJ이었다.

• Current Optics and Photonics
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• 제7권6호
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• pp.708-713
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• 2023

A robust all-fiber nonlinear amplifying loop-mirror-based mode-locked femtosecond laser is demonstrated. Power-dependent nonlinear phase shift in a Sagnac loop enables stable and power-efficient mode-locking working as an artificial saturable absorber. The pump power is adjusted to achieve the lowest intensity noise for stable long-term operation. The minimum pump power for mode-locking is 180 mW, and the optimal pump power is 300 mW. The lowest integrated root-mean-square relative intensity noise of a free-running mode-locked laser is 0.009% [integration bandwidth: 1 Hz-10 MHz]. The long-term repetition-rate instability of a free-running mode-locked laser is 10^-7 over 1,000 s averaging time. The repetition-rate phase noise scaled at 10-GHz carrier is -122 dBc/Hz at 10 kHz Fourier frequency. The demonstrated method can be applied as a seed source in high-precision real-time mid-infrared molecular spectroscopy.

• 전기전자학회논문지
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• 제14권2호
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• pp.9-15
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• 2010

In this study, we have been proposed the new type of a transcranial magnetic stimulation adopted a variable voltage capacitor with Cockcroft-Walton circuit and constant-frequency current resonant half-bridge inverter. This a transcranial magnetic stimulation has some merits compared with the conventional one. First, it doesn't require the high voltage transformer. And second, it has less switching losses, compact size and capability in adjusting the transcranial magnetic stimulation output energy precisely. In this paper, we have performed the output characteristics of a transcranial magnetic stimulation system which is well known as magnetic stimulation. The tested results are described as a function of pulse repetition rate and switching numbers of the half-bridge inverter.

• 한국광학회:학술대회논문집
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• 한국광학회 2009년도 동계학술발표회 논문집
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• pp.269-270
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• 2009

• 한국광학회:학술대회논문집
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• 한국광학회 2003년도 제14회 정기총회 및 03년 동계학술발표회
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• pp.44-44
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• 2003

Free electron lasers (FEL) have, at least, the following advantages in comparison to conventional lasers： FEL can be designed for any arbitrary given emission wavelength. It is continuously tunable within wide band. Easy to get single-mode emission. Easily controlled emission structure (pulse duration, repetition rate, and pulse energy). (omitted)

• 한국통신학회논문지
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• 제28권12C호
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• pp.1192-1199
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• 2003

본 논문에서는 다중경로 채널 환경에서 펄스 반복 빈도 (pulse repetition frequency, PRF)와 슬롯 시간이 UWB (ultra wide band) 무선 통신 시스템의 데이터 전송율 (throughput) 성능에 미치는 영향을 조사하고 이를 기반하여 유효 데이터 전송율이 최대화되도록 하는 PRF와 슬롯 시간을 이용한 전송율 제어를 제안한다. 최근에 UWB 시스템이 갖고 있는 장점으로 인하여 근거리 고속 무선 데이터 전송과 관련하여 관심이 고조되고 있다. UWB 시스템에서는 데이터 전송율을 결정짓는 파라미터로는 펄스를 반복하는 펄스 반복 회수와 펄스간의 간격을 결정짓는 슬롯 시간을 들 수 있다. AWGN이 존재하는 다중경로 채널 하에 있는 UWB 시스템은 펄스간의 간섭(inter-pulse interference, IPI)과 잡음에 의하여 시스템 성능이 저하된다. UWB 시스템은 이 두 파라미터의 조정을 통하여 시스템의 성능을 유지 또는 개선할 수 있다. 본 논문에서는 두 파라미터의 변화가 다양한 채널 환경에서 데이터 전송율에 미치는 영향을 모의실험을 통하여 관측하고 이를 기반하여 설계된 가변 전송율을 사용하는 것이 비가변적인 방법에 비하여 유효 데이터 전송율 측면에서 우수함을 모의실험을 통하여 검증하였다.

• 한국지역사회생활과학회지
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• 제18권3호
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• pp.391-398
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• 2007

Ginkgo leaves, which have been known as medical materials, were selected as new natural dyes in this study, in which it was examined whether they have the function of UV-blocker or not. Cotton, linen & Hanji(Korean traditional paper) were dyed with Ginkgo. Al, Cr, Cu, Fe and Sn were selected as mordants. UV-blocking rate of dyed samples was measured after dyeing and mordant treatment. The results of this study are as follows. First, most surface color of dyed samples was yellow except that Hanji mordanted with Cu was yellowish red. Second, dyeing repetition had positive correlations with K/S values of cotton ($r=.\;758^{**}$), linen ($r=.\;500^*$) and Hanji ($r=.\;819^{**}$), because K/S values were increased according to dyeing repetition. Third, solar UV-blocking rates had positive correlations with dyeing repetitions (p<0.01), because UV-blocking rates had increased according to dyeing repetition. Fourth, UV-blocking ability of Hanji was highest among samples, as UV-blocking rates of cotton and linen dyed after 3 dyeing repetition were up to 93%, Hanji's values were up to 98%. Therefore, it was proven that Ginkgo extracts used in this experiment as dyestuff have excellent dyeing ability and high UV-blocking ability. It is hoped that this work will lead to further research to confirm the physiological effects when human wear the clothes made from Hanji.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 영호남학술대회 논문집
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• pp.82-85
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• 2000

We introduce pulsed $CO_2$ laser power supply excited by half-wave rectified 60Hz AC discharge some advantage of cost and size compared to a typical pulsed power supply. AC frequency is adjusted from 10Hz to 60Hz to control laser output. In this laser, a low voltage open loop control for high voltage AC discharge circuits is employed to avoid the HV sampling or switching. The control is achieved by using a ZCS circuit and a PIC one-chip microprocessor that control the gate signal of SCR precisely. The pulse repetition rate is limited by 60Hz due to a high leakage inductance. The maximum laser output was obtained about 20W at the condition of total pressure, 18Torr and pulse repetition rate,60Hz.

• 한국산업융합학회 논문집
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• 제4권3호
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• pp.311-318
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• 2001

The application of a pulsed power system is being extended to a environmental and industrial fields. The non-dissolution waste water pollutants from industrial plants can be processed by applying high voltage pulses with a fast rising time (a few nanoseconds) and short duration (nano to microseconds) in a pulsed corona discharge reactor. The nano-pulse generator with a magnetic switch has been developed. Its corona current in load can be adjusted by pulse width and repetition rate. we investigated the performance of the nano-pulse generator using the dummy load which is composed of resistor and capacitor equivalent to the actual reactor. This paper descibes the electrical characteristics of the nano-pulse generator that produces a 300 ns pulse at maximum repetition rate of 400 pps with a voltage of 40 kV across a $640{\Omega}$ load. In this paper we briefly discuss a configuration of system and test results.