• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.391-392
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• 2008

• 한국광학회지
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• 제17권5호
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• pp.455-460
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• 2006

광섬유 연결 반도체레이저를 여기원으로 하는 단면여기 세라믹 Nd:YAG 레이저의 출력 특성과 레이저 출력에 영향을 미치는 열 영향에 대하여 연구하였다. 반사율이 90.4 %인 출력거울을 사용하였을 경우 약 33.8 %의 최대 출력 효율을 얻었고, 기울기 효율은 39.3 %를 나타내었다. 세라믹 Nd:YAG의 열렌즈 효과에 의해 여기 파워 6 W 이상에서 출력 감소 현상이 나타났으며, 12 W 부근에서 레이저가 발진되지 않았다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 제14회 신호처리 합동 학술대회 논문집
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• pp.777-783
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• 2001

This paper is mainly concerned with the state of the practical developments of a constants PWM bridge type resonants DC-DC suitable converter for Nd:YAG Laser with a Microprocessor. (PIC16C54 & 8051) The use of IGBT power supply with feedback control of flashLamp currents imparts a advantages to Nd:YAG Laser for materials processing. these include the alility to tailor the pulseshape and modify pulse parameters on a pulse- by pulse basis. And Correct choice of pulseshape can enhance the repeatability of the process. as higher power IGBT became available, act ive pulseforming power supplies will find greater user in deep hole drilling machine By Using certain control tecniques, utililized in designing Pic16c54 from Microchip technology and Intel 8051, also Mornitoring from Microsoft Visual Basic 5, And it allowed us to designed and fabricate ahigh repel it ion rate and high power(HRHP) pulsed Nd:YAG laser system, As a result of that, the current pulsewidth could be contort led 200s to 350s(step 50s) , and the pulse repetition rate could be adjusted 500pps to 1150pps. In addition, in the case of one laser head consisting of a Nd:YAG laser rod and two flashlamps , the maximum laser output of 240w was produced at the condition of 350s and 1150pps, and that of about 480w was generated at the same condition when two laser heads were arranged in cascade.

• 한국정밀공학회지
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• 제20권7호
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• pp.44-55
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• 2003

The Nd:YAG laser process is known to have high speed and deep penetration capability to become one of the most advanced welding technologies. This paper describes the machining characteristics of SM45C carbon steel welding by use of an Nd:YAG laser. In spite of its good mechanical characteristics, SM45C carbon steel has a high carbon contents and suffers a limitation in the industrial application due to the poor welding properties. The major process parameters studied in the present laser welding experiment were position of focus, travel speed and laser power. Optical microscope and SEM were used to investigate the microstructures of the welded zone. The experimental results showed that penetration depth of the welding process increases with laser power. Both the microstructural investigation and the theoretical calculations indicated that materials undergoes a very high heating and cooling cycle during welding process. It was also found that the austenite nucleation takes place at the initial stage and the completion temperature of austenite transformation is much higher than in the case of the arc welding.

• 한국기계가공학회지
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• 제5권1호
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• pp.51-58
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• 2006

The objective of this research work is to investigate into heat transfer characteristics of the laser cutting of CSP 1N sheet using high power CW Nd:YAG laser. In order to investigate the heat transfer characteristics, three dimensional quasi stationary and steady-state heat transfer analysis has been carried out. The laser heat source is assumed as a volumetric heat source with a gaussian heat distribution in a plane. Through the comparison of the results of analyses with those of experiments, the proper finite element model has been obtained. In addition, characteristics of the three-dimensional heat transfer and temperature distribution have been estimated by the finite element model. Finally, the minimum temperature at the center for cutting of the material has been estimated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1159-1165
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• 2003

The Nd:YAG laser process is known to have high speed and deep penetration capability to become one of the most advanced welding technologies. In spite of its good mechanical characteristics, SM45C carbon steel has a high carbon contents and suffers a limitation in the industrial application due to the poor welding properties. The major process parameters studied in the present laser welding experiment were position of focus, travel speed and laser power.

• 한국레이저가공학회지
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• 제4권2호
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• pp.47-57
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• 2001

This study deals with the laser cutting of stencil for the PCB. The most important aim of this study is to determine optimal conditions which make good-qualify stencil in Nd:YAG laser cutting. We made an experiment according to various variables (power. type of mask. gas pressure, cutting speed, and pulse width) and analyzed the cutting characteristics (surface roughness, kerf width. dross) . Each variable has optimal value for good-qualify cut edge under fixed condition. And neural network after learning experimental data with a million time iteration could predict surface roughness of cut edge under arbitrary condition approximately.

• 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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• 제12권6호
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• pp.489-495
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• 2001

난반사체를 이용한 다이오드 횡여기 Nd:YAG 레이저 헤드의 설계코드를 개발하여 레이저 결정 내 홉수된 빔의 균일성과 최대 레이저 출력을 갖는 설계요소의 조건에 관해 분석하고, 수치해석 방법으로 열렌즈 효과를 고려한 레이저 공진기의 레이저 출력을 계산하고 실험치와 비교 분석하였다. 1,080W의 여기광 출력에서 측정된 약 504 W의 레이저 출력은 열렌즈 효과를 고려하여 수치 해석적으로 계산된 레이저 출력과 레이저 공진기의 안정영역에서 거의 일치함을 확인하였다.

• 한국광학회:학술대회논문집
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• 한국광학회 1998년도 제15회 광학 및 양자전자 학술발표회 논문집
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• pp.82-83
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• 1998