• 한국항공우주학회지
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• 제48권6호
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• pp.479-487
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• 2020

본 논문에서는 라만 분광법과 레이저 유도 플라즈마 분광법(LIPS)을 단일 유닛으로 결합한 새로운 형태의 이중 펄스 레이저 시스템을 제안하였다. 본 연구는 라만 분광법으로부터 분자 신호를 추출하면서, 동시에 레이저 유도 플라즈마 방출 신호를 향상시키고자 하였다. 달의 대기압과 같은 저압 조건에서는 플라즈마 신호 검출은 낮은 전자 밀도와 짧은 지속시간, 빠른 플라즈마 팽창 때문에 어려움을 마주치게 된다. 또한, 우주 탐사를 목표로 하는 검출 시스템의 통합에서, 레이저 시스템의 무게 최소화는 payload의 무게 측면에서 중요하다. 0.07 torr 미만의 저압 조건에서 높은 분해능의 스펙트럼 데이터를 제공하는 본 연구의 동시 분자 및 원자 검출방식은 8개의 암석을 이용하여 증명되었다. 이중 펄스 레이저로부터 생성된 연속된 플라즈마는 종래의 플라즈마 분광과 비교하여 방해석의 산소와 칼슘 신호를 2배 향상시킬 수 있었다.

• 한국광학회:학술대회논문집
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• 한국광학회 1991년도 제6회 파동 및 레이저 학술발표회 Prodeedings of 6th Conference on Waves and Lasers
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• pp.64-64
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• 1991

The interaction of high-intensity, focused, nanosecond laser light with matter results in the production of high-temperature plasma, which in turn emits an intense pulse of x rays. The x-ray spectrum consists of strong line components of several keV photon energy and broad continuum. Such an x-ray source provides many advantages over conventional ones for many applications. Pulse nature of the x-ray emission is well-suited for studying transient phenomena and for imaging living biological specimen. Recent experiments have also shown that the laser plasma x ray may be used for x ray lithography. These studies and other applications will be discussed in detail.

• 한국입자에어로졸학회지
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• 제16권1호
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• pp.1-8
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• 2020

Nano-pulse plasma technology has great potential as the process simplicity, high efficiency and low energy consumption for SO₂ removal. The research on the gas-to-particle conversion is required to achieve higher efficiency of SO₂ gas removal. Thus, we studied the effect of the relative humidity, NH₃ concentration and applied voltage of the nano-pulse plasma system in the gas to particle conversion of SO₂. The particles from the conversions were increased from 10 to 100 nm in diameter as relative humidity, NH₃ concentration, applied voltage increases. With these results, nano-pulse plasma system can be used to more efficient removal of SO₂ gas by controlling above parameters.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 심포지엄 논문집 정보 및 제어부문
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• pp.282-284
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• 2006

UV lamp systems have been used for cleaning of display pannels of TFT LCD or Plasma Display Pannel (PDP). However, the needs for high efficient cleaning and low cost made high voltage plasma cleaning techniques be developed and improved. In this paper, 3kW high voltage plasma power supply system was developed for LCD cleaning. The 3-phase input voltage is rectified and then inverter system is used to make a high frequency pulse train, which is rectified after passing through a high-power transformer. Finally, bi-directional high voltage pulse switching circuits are used to generate the high voltage plasma.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2014년도 추계학술대회 논문집
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• pp.197-197
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• 2014

Plasma를 이용하는 반도체 공정에서 high density, plasma uniformity 및 electron temperature와 같은 plasma 특성을 조절하는 것은 차세대 공정 장비 개발에 있어서 매우 중요한 요소이다. 본 연구에서는 이를 위해 2개의 다른 주파수를 사용하는 spiral type의 안테나에 pulse를 적용시켜 각각 인가되는 power를 조절함으로써 plasma의 특성을 조절하고자 하였다. 또한 pulse plasma를 적용하여 다양한 duty ratio 조건에서 plasma 특성을 확인하였으며 식각 공정을 통하여 etch selectivity를 향상시키려 하였다.

• 한국표면공학회지
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• 제48권6호
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• pp.360-370
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• 2015

As the size of the semiconductor devices shrinks to nanometer scale, the importance of plasma etching process to the fabrication of nanometer scale semiconductor devices is increasing further and further. But for the nanoscale devices, conventional plasma etching technique is extremely difficult to meet the requirement of the device fabrication, therefore, other etching techniques such as use of multi frequency plasma, source/bias/gas pulsing, etc. are investigated to meet the etching target. Until today, various pulsing techniques including pulsed plasma source and/or pulse-biased plasma etching have been tested on various materials. In this review, the experimental/theoretical studies of pulsed plasmas during the nanoscale plasma etching on etch profile, etch selectivity, uniformity, etc. have been summarized. Especially, the researches of pulsed plasma on the etching of silicon, $SiO_2$, and magnetic materials in the semiconductor industry for further device scaling have been discussed. Those results demonstrated the importance of pulse plasma on the pattern control for achieving the best performance. Although some of the pulsing mechanism is not well established, it is believed that this review will give a certain understanding on the pulsed plasma techniques.

• 한국연소학회지
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• 제10권4호
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• pp.24-32
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• 2005

Various types of plasma source applied in $CH_4$ decomposition process are compared. DBD by pulse and AC power, spark by pulse and AC power, rotating arc and hollow cathode plasma are chosen to be compared. The results show that $CH_4$ conversion per given unit power is relatively high in hollow cathode plasma and rotating arc that induces rather high temperature condition and that is why both thermal dehydration and plasma induced decomposition contribute for the overall process. In case of DBD wherein high temperature electron and low temperature gas molecule coexist, the process shows low conversion rate, for in rather low temperature condition the contribution of thermal dehydration is lowered. Selectivity of $C_2H_6$ and $C_2H_2$ is shown to be a good parameter of the relative contribution of plasma chemistry in the overall process. From the results we concluded that required condition of plasma source for a cost effective and high yield $CH_4$ decomposition is to have characteristics of both thermal plasma and non thermal plasma in which temperature is high above a certain threshold state for thermal dehydration and electron induced collision is maximized in the same breath.

• 한국광학회:학술대회논문집
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• 한국광학회 2002년도 하계학술발표회
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• pp.230-231
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• 2002

Recently, analysis of transient Raman backscattering in a plasma reported(2.3) that it is possible to reach 10$\^$17/ W/cm$^2$ for 1 micrometer wavelength laser pulse with a counter-propagating pump pulse. The basic mechanism is like this ： whorl the two counter-propagating waves in a plasma satisfy the condition of Raman backscattering, w$\_$0/ ： w$\_$1/ ＋ w$\_$p/, energy is transferred from the long pulse to the short pulse via three wave interaction(4). (omitted)

• 조명전기설비학회논문지
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• 제27권7호
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• pp.52-58
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• 2013

The two-dimensional finite difference time domain algorithm is used to numerically reconstruct the electron density profile in O-mode ultrashort pulse reflectometry. A Gaussian pulse is employed as the source of a probing electromagnetic wave. The Gaussian pulse duration is chosen in such a manner as to have its frequency spectrum cover the whole range of the plasma frequency. By using a number of numerical band-pass filters, it is possible to compute the time delays of the frequency components of the reflected signal from the plasma. The electron density profile is reconstructed by substituting the time delays into the Abel integral equation. As a result of simulation, the reconstructed electron density profile agrees well with the assumed profile.

• 한국표면공학회지
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• 제55권5호
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• pp.292-298
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• 2022

In this study, PEO (plasma electrolytic oxidation) film formation behavior of AZ31 Mg alloy under application of 300 Hz pulse current was studied by the analyses of V-t curve, arc generation behavior, PEO film thickness and morphology of PEO films with treatment time in 0.05 M NaOH + 0.05 M Na₂SiO₃ + 0.1 M NaF solution. PEO films was observed to grow after 10 s of application of pulse current together with generation of micro-arcs. PEO film grew linearly with treatment time at a growth rate of about 5.58 ㎛/min at 200 mA/cm² of pulse current but increasing rate of film formation voltage became lowered largely with increasing treatment time after passing about 250 V, suggesting that resistivity of PEO films during micro-arc generation decreases with increasing film formation voltage at more than 250 V.