• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.5
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• pp.236-240
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• 2004

In this paper we examine the reflection characteristics of dielectric microstrip lines with open-ended termination containing an optically induced plasma region, which are analyzed by the assumption that the plasma is distributed homogeneously in laser illumination. The characteristics impedances resulting from the presence of plasma are evaluated by the transmission line model. To estimate theoretically the characteristic response of identical systems in the time domain, the Fourier transformation method is evaluated. The reflection characteristics of time and frequency response in microwave systems have been calculated using an equivalent circuit model.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1187-1190
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• 2004

In this paper we analyze the reflection characteristics of a dielectric microstrip line with an open-end termination containing optically induced plasma region, which are analyzed by the assumption that the plasma is distributed homogeneously in the laser illumination. The characteristics impedances resulting from the presence of plasma are evaluated the transmission line model. To estimate theoretically the characteristic response of same systems in the time domain, the Fourier transformation method is evaluated. The reflection characteristics of time response in microwave systems have been calculated.

• Laser Solutions
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• v.17 no.4
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• pp.7-13
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• 2014

In this work, the application of laser induced breakdown spectroscopy (LIBS) for the composition analysis of thin $Cu(In,Ga)Se_2$ (CIGS) solar cell films ($1-2{\mu}m$ thickness) is reported. For the ablation of CIGS films, femtosecond (fs) laser (wavelength = 343nm, pulse width = 500fs) and nanosecond (ns) laser (wavelength = 266nm, pulse width = 5ns) were used under atmospheric environment. The emission spectra were detected with an intensified charge coupled device (ICCD) spectrometer and multichannel CCD spectrometer for fs-LIBS and ns-LIBS, respectively. The calibration curves for fs-LIBS and ns-LIBS intensity ratios of Ga/Cu, In/Cu, and Ga/In were generated with respect to the concentration ratios measured by inductively coupled plasma optical emission spectrometry (ICP-OES).

• Journal of Welding and Joining
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• v.16 no.1
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• pp.77-87
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• 1998

This paper deals with the effect of laser welding parameters on the weld formation. Thin steels for automotive application were prepared so as to be welded with high power carbon dioxide laser system. Major process parameters were position of focus and travel speed. The effect of shielding gas was also discussed by employing the high speed photometry. Test results showed that the optimal position of focus varied in accordance with the joint configuration; bead-on-plate, butt or lap welding. It was recommended that the position of focus for the lap welding be located at slightly inner part of the material to be welded. In this case, however, it was noticeable that the weld penetration ratio, d/t$_{0}$ dropped drastically at the critical region. Results also demonstrated that both the bead width and penetration reduced as the travel speed increased. The penetration ratio showed two distinct regions; stabilized zone at the lower range of the travel spped and sudden drop zone at the higher range of travel speed. Lower limit of the penetration for acceptable weld was proved to be about 90% of the parent metal thickness based on the physical properties of the weld. Mixed gas application for both the shielding of molten metal and laser induced plasma control was recommended as far as the penetration was concerned.d.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.129-134
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• 2004

The development of fabrication processes of polycrystalline-silicon-thin-film transistors (poly-Si TFTs) at low temperatures is reviewed. Rapid crystallization through laser-induced melt-regrowth has an advantage of formation of crystalline silicon films at a low thermal budget. Solid phase crystallization techniques have also been improved for low temperature processing. Passivation of $SiO_2$/Si interface and grain boundaries is important to achieve high carrier transport properties. Oxygen plasma and $H_2O$ vapor heat treatments are proposed for effective reduction of the density of defect states. TFTs with high performance is reported.

• Proceedings of the KWS Conference
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• 2003.11a
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• pp.27-29
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• 2003

최근 레이저와 아크를 동시에 사용하여 용접 속도와 품질을 향상시킬 수 있는 하이브리드 용접 기술이 개발되어 활발히 연구가 진행되고 있다. 레이저와 아크를 동시에 사용하게 되면 각각의 열원이 서로 영향을 주어 새로운 용접 열원으로서 동작하게 되는데 특히 레이저에 의해서 발생하는 모재의 금속 증기는 아크 플라즈마의 안정화를 가져오는 것으로 알려져 있다. 또한 금속 증기 속의 이온과 전자가 아크 플라즈마의 음극점을 형성하는데 도움을 줌으로써 플라즈마의 국부적인 온도 상승을 가져오게 된다. 본 연구에서는 effective electrical potential 개념을 도입하여 이러한 현상을 해석하였고 용접 조건에 따른 플라즈마의 거동 변화를 시뮬레이션 하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.151-152
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• 2012

라만(Raman) 분광법은 실리콘의 결정화도를 분석하는데 가장 유용하게 쓰이는 기법이다. 본 논문에서는 상압 플라즈마 화학기상증착법 (atmospheric pressure plasma-enhanced chemical vapor deposition, AP-PECVD)에 의해 형성된 실리콘 박막의 결정화도를 라만 분광법에 의해 분석하였다. 라만 분석 시, 조사하는 레이져의 파장에 따라서 실리콘 박막 내로의 침투깊이가 결정된다. 또한 레이져의 파워가 임계점을 넘게 되면, 레이져에 의한 실리콘의 결정화가 진행되는 것을 확인하였다.

• Transactions on Electrical and Electronic Materials
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• v.12 no.3
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• pp.89-92
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• 2011

Hydrogenated amorphous carbon (a-C:H) films were deposited by plasma enhanced chemical vapor deposition on silicon substrates. a-C:H thin film was irradiated to a typical He-Cd laser to study its emitting properties. The photoluminescence (PL) intensity during the irradiation achieved a maximum value when 2,000 seconds elapsed. Fourier transform infrared measurement revealed a-C:H thin film suffered transformation from a polymer-like to graphite-like phase during laser irradiation. Thermal annealing was done at various temperatures, ranging from room temperature to $400^{\circ}C$ in the atmosphere, to investigate structural changes in a-C:H film by heat generation during the emission. PL intensity of a-C:H thin film increased 1.5 times without apparent structural change, as annealing temperature increased up to $200^{\circ}C$. However, a-C:H film above $200^{\circ}C$ exhibited significant decrease of PL accompanying dehydrogenation. This led to a red shift of the PL peak.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.7
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• pp.71-76
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• 2019

The diffusion of the drug component of the inflammatory patch into the living tissue was analyzed by laser induced plasma spectroscopy (LIBS). Calcium element, which is a diffusion catalyst of the drug in the inflammatory analgesic patch, is transferred into the body through the diffusion process of the substance. The test pieces used in the experiment are pig skin tissues which are similar to human skin. As a result, the diffusion coefficient D of the calcium element was found to be average $8.24{\times}10^{-2}({\mu}m^2/s)$. Experimental results showed that the most influential factors on the diffusion of materials were temperature variables.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.14
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• pp.5589-5594
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• 2015

Cystitis and proctitis are defined as inflammation of bladder and rectum respectively. Haemorrhagic cystitis is the most severe clinical manifestation of radiation and chemical cystitis. Radiation proctitis and cystitis are major complications following radiotherapy. Prevention of radiation-induced haemorrhagic cystitis has been investigated using various oral agents with minimal benefit. Bladder irrigation remains the most frequently adopted modality followed by intra-vesical instillation of alum or formalin. In intractable cases, surgical intervention is required in the form of diversion ureterostomy or cystectomy. Proctitis is more common in even low dose ranges but is self-limiting and improves on treatment interruption. However, treatment of radiation proctitis is broadly non-invasive or invasive. Non-invasive treatment consists of non-steroid anti-inflammatory drugs (NSAIDs), anti-oxidants, sucralfate, short chain fatty acids and hyperbaric oxygen. Invasive treatment consists of ablative procedures like formalin application, endoscopic YAG laser coagulation or argon plasma coagulation and surgery as a last resort.