• 한국레이저가공학회지
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• 제12권4호
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• pp.17-25
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• 2009

The surface cleaning method based on the laser-induced breakdown (LIB) of gas and subsequent plasma and shock wave generation can remove small particles from solid surfaces. In the laser shock cleaning (LSC) process, a high-power laser pulse induces optical breakdown of the ambient gas above the solid surface covered with contaminant particles. The subsequently created shock wave followed by a high-speed flow stream detaches the particles. In this work, a novel surface cleaning process using laser-induced breakdown of liquid is introduced and demonstrated. LIB of a micro liquid jet increases the shock wave intensity and thus removes smaller particle than the conventional LSC method. Experiments demonstrate that the cleaning force and cleaning efficiency are also increased significantly by this method.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2001년도 춘계학술발표대회 개요집
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• pp.176-177
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• 2001

• 한국레이저가공학회:학술대회논문집
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• 한국레이저가공학회 1998년도 춘계학술발표대회 초록개요집
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• pp.15-17
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• 1998

• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 하계학술발표회
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• pp.214-215
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• 2000

레이저로 발생시킨 플라즈마의 분광학적인 분석은 유용한 분석기술로 평가되고 있다. 이러한 플라즈마를 발생시키는데 있어서 Q-switched 레이저를 많이 사용되고 되고 있으나, Q-switch된 레이저로 발생시킨 플라즈마 복사광의 특성은 주변 분위기에 의해 매우 큰 영향을 받는다. 특히 대기압인 공기분위기에서 레이저로 발생된 플라즈마의 분광특성은 강하고 연속적인 background가 포함되고, 자체적으로 흡수되고, 넓게 퍼진 분광선들이 생성된다. 이는 레이저 발생 플라즈마를 통해 성분을 분석할 경우에 적합하지 않다. (중략)

• 한국항공우주학회지
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• 제39권5호
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• pp.451-457
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• 2011

레이저 조사 시 발생되는 플라즈마는 물질에 따라 특정한 파장의 빛을 방출하므로, 이 빛을 수집하여 물질의 구성 성분을 정성 정량적으로 분석할 수 있다. LIBS(Laser-Induced Breakdown Spectroscopy)는 실시간에 가까운 분석과 원거리 검출이 가능하다는 점에서 우주 자원 탐사 기술로 주목받고 있다. 본 연구에서는 달 환경, 즉 고진공 하에서의 성분 분석을 위하여 double-pulse LIBS 기법을 이용하여 LIBS 신호 세기를 크게 증가시켰다. 또한 시편에 레이저가 조사되는 각도를 조절하여 임의 형상 물질의 분석을 모사하였다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.176-180
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• 2002

During the last two decades the laser beam has progressed from a sophisticated laboratory apparatus to an adaptable and viable industrial tool. Especially, in its welding mode, the laser offers high travel speed, low distortion, and narrow fusion and heat-affected zones (HAZ). The principal obstacle to selection of a laser processing method in production is its relatively high equipment cost and the natural unwillingness of production supervision to try something new until it is thoroughly proven. The major objective of this work is focused on the combined features of gas tungsten arc and a low-power cold laser beam. Although high-power laser beams have been combined with the plasma from a gas tungsten arc (GTA) torch for use in welding as early as 1980, recent work at the Ohio State University has employed a low power laser beam to initiate, direct, and concentrate a gas tungsten arcs. In this work, the laser beam from a 7 watts carbon monoxide laser was combined with electrical discharges from a short-pulsed capacitive discharge GTA welding power supply. When the low power CO laser beam passes through a special composition shielding gas, the CO molecules in the gas absorbs the radiation, and ionizes through a process known as non-equilibrium, vibration-vibration pumping. The resulting laser-induced plasma (LIP) was positioned between various configurations of electrodes. The high-voltage impulse applied to the electrodes forced rapid electrical breakdown between the electrodes. Electrical discharges between tungsten electrodes and aluminum sheet specimens followed the ionized path provided by LIP. The result was well focused melted spots.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.149-149
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• 2012

We introduce Helicon discharge plasma source and Laser Thomson scattering system recently finished an installation in KRISS. Laser Thomson scattering method is promising for diagnostics in Helicon plasma because a measurement by electrical probe typically used has significant errors due to the gyromotion of electrons induced by high magnetic field. However, we found that LTS is affected by magnetic field so that we applied the normalization method for processing data and the results show a clear Maxwellian distribution at various conditions of magnetic field and RF power at low energy part without distortion.

• Journal of Advanced Marine Engineering and Technology
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• 제23권4호
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• pp.514-522
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• 1999

The laser-induced plasma affects greatly on the results of welding process. moreover selective evaporation loss of alloying elements leads to change in chemical composition of weld metal as well as the mechanical properties of welded joint. this study was undertaken to obtain a fundamental knowledge of pulsed laser welding phenomena especially evaporation mechanism of different aluminum alloys. The intensities of molecular spectra of AlO and MgO were different each other depeding on the power density of a laser beam Under the low power density condition the MgO band spectrum was predominant in intensity while the AlO spectra became much stronger with an increase in the power density. These behaviors have been attributed to the difference in evaporation phenomena of Al and Mg metals with different boiling points and latent heats of vaporization. The time-averaged plasma temperature and electron number density were determined by spectroscopic methods and consequently the obtained temperature was $3,280{\pm}150K$ and the electron number density was $1.85{\times}10^{19}\;l/m^3$.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.251-256
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• 2004

A concept in which laser-sustained plasmas (LSPs) are combined with inductively coupled plasmas (ICPs) is proposed. The concept is aiming at extensions of operative conditions of a CW laser thruster due to the fact that the ICP has some characteristics which are in contrast to those of LSPs. An estimation confirmed that the concept would effectively work. And a fundamental experiment was conducted. The results showed that the radio frequency magnetic field induced by a alternate current of 13.56 MHz coupled inductively with LSPs, resulting in the enlargement of the plasma region and the attainment of the enthalpy. It is expected that some improvements will enable to transfer the RF power to the work gas more effectively and to demonstrate the synergy effect between the LSPs and the ICPs.

• 분석과학
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• 제22권2호
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• pp.141-147
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• 2009

Laser induced breakdown spectroscopy (LIBS)의 정량분석에 대한 측정의 정확도를 향상시키고자, 플라즈마의 특성을 분석하여, 상대적으로 안정적인 Outer sphere에 해당하는 영역을 측정하는 방법으로 Cu alloy sample을 측정하여 분석하였다. 신호의 높은 재현성을 고려한 측정 조건에서 측정이 수행되었으며, 600 mtorr 진공상태에서 20 mm정도의 크기로 플라즈마를 성장시켜, Outer sphere 영역인 플라즈마 성장방향으로 6.0 mm 지점을 측정하였다. 그 결과 Cu의 선형 분석 $R^2$ 값은 0.9886로, Ni의 $R^2$ 값은 0.9988로 획득하였으며, 측정오차는 Ni의 경우 기존보다는 향상된 0.78%의 측정오차를 획득하였다.