• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2192-2194
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• 1999

In this study, We have accomplished a new approach to develope a cheap and compact pulsed $CO_2$ laser system. We used a fast SCR as switching device instead of a thyatron in the pulsed power supply. Using the Pulse transformer, energy in the condenser is tranferred to the secondary, electrodes of discharge tube, from the primary. An axial and water cooled type was adopted as the laser cavity. The laser performance characteristics as various parameters, such as gas pressure and pulse repetition rate, have been investigated. As a result, the maxium laser output was 12.3[W] at a pulse repetition rate of 120[pps] and a filling pressure of 12[Torr].

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.2138-2139
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• 2005

We demonstrate a simple CO2 laser by controlling firing angle of a TRIAC switch in ac power line. The power supply for our laser system switches the voltage of the AC power line (60Hz) directly. The power supply does not need elements such as a rectifier bridge, energy-storage capacitors, or a current-limiting resistor in the discharge circuit. In order to control the laser output power, the pulse repetition rate is adjusted up to 60Hz and the firing angle of TRIAC gate is varied from 45 to 135. A ZCS(Zero Crossing Switch) circuit and a PIC one-chip microprocessor are used to control the gate signal of the TRIAC precisely. The maximum laser output of 40W is obtained at a total pressure of 18Torr, a pulse repetition rate of 60Hz, and a TRAIC gate firing angle of 90.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 추계학술대회 논문집 - 한국공작기계학회
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• pp.554-559
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• 1999

The purpose of this study is the machining of texture shapes by the contour fitting data. The hardware of the system comprises PC and scanning system, CO2 laser machine. There are four steps, (1) text image loading using scanning shapes or 2D image files, (2) generation of contour fitting data by the line and arc, cubic Bezier curve, (3) generation of NC code from the contouring fitting data, (4) machining by the DNC system. It is developed a software package, with which can conduct a micro CAM system of CNC laser machine in the PC without economical burden.

• 한국레이저가공학회지
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• 제4권3호
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• pp.40-44
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• 2001

Microbump formation during CO$_2$ laser texturing of glass substrates is examined in this paper. Experimental results show that different bump shapes (dome-shaped, with a central dimple, and with a peripheral rim) are generated depending on the laser fluence. A theoretical model for the process is suggested based on thermoelastic behavior but limited only to the dome-shaped bump. The dimensions (maximum height and base area) of the bump shows a logarithmic dependence on laser fluence as expected from the theory. Numerical computation reveals that the effect of thermal diffusion is not negligible for relatively long laser pulses.

• 한국광학회지
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• 제25권4호
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• pp.200-206
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• 2014

본 논문에서는 직경 $125{\mu}m$의 싱글모드 광섬유에 입사된 빔을 다방향으로 방사하기 위하여 이론적으로 계산된 값을 광학설계 프로그램인 LightTools를 이용하여 광섬유 끝단에 원뿔형 구조물을 모델링 하고 입사된 모든 빔이 전반사 되어 측면으로 방사되는 광섬유 팁과, 전방과 측면으로 동시에 방사가 가능한 광섬유 팁에 대해 시뮬레이션을 하였다. 이러한 결과를 가지고 광섬유 끝단에 펨토초 레이저와 $CO_2$ 레이저를 이용하여 원뿔형 구조물을 제작하고 시뮬레이션 결과와 비교 분석하는 연구를 수행하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계합동학술대회 논문집
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• pp.172-175
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• 2002

The technique of induced discharge by a pulsed CO2 laser is being applied to control electrical discharge path, material processing, triggered lightning for protecting the power equipments. In this paper, we have investigated about the characteristics of the induced discharge at atmospheric conditions by using a plasma channel, which is produced when a pulsed CO2 laser radiation is focused by a focusing mirror as a trigger source. A plasma channel produced by laser radiation has an effect on decreasing the threshold voltage and inducing the discharge in both needle electrodes. We have confirmed a delay time between a produced plasma channel and an electrical discharge after laser radiation. We provided the decreased voltage lower than the natural discharge voltage between electrode type of needles and was induced the discharge by forming a plasma channel between them. In this research we could understand the time delay of induced discharge by laser radiation, and the characteristics of the discharge cause by the decrease in the threshold voltage, and the polarity effect by changes of plasma channel positions between two electrodes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(I)
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• pp.539-541
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• 1987

P+ ion implanted poly-Si flim with doses of 10E13-10E16 ions/$cm^2$ were annealed by CO2 laser and their sheet resistances were measured and compared with thoses of furnace annealed samples. In case of lightly doped samples, the measured sheet resistance of laser annealed samples were lower several orders of magnitude than those of furnace annealed samples. The origin of this reduction of sheet resistances is supposed to be the increase of the grain size to the extent of certain critical value.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.763-766
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• 2000

The Rapid Prototyping and Tooling technology has been developed. However, most commercial ones currently use resins or waxes as the raw materials. These days. the direct metal deposition methods are researched as a true rapid prototyping and tooling technology. A fundamental study on rapid prototyping and tooling with wire welding technology using $CO_2$ laser radiation was carried out in this paper. The main focus is to develop a simple commercial rapid prototyping and tooling system with the exiting laser welding technology. The process is investigated as a function of laser parameters and process variables. Basic parts were fabricated as out-put and their microstructure, hardness and tensile strength are examined for the reliability. In addition, Its advantages and disadvantages are discussed as a rapid prototyping and tooling system.

• Journal of Photoscience
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• 제5권1호
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• pp.39-43
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• 1998

Pulsed Er: YAG and CO$_2$ lasers induced temperature rise of tissue is studied using axisymmetric, two-dimensional, and transient Pennes bio-heat equation for elucidating the implications of skin resurfacing. Modeling indicates that Er:YAG laser induced temperature has much higher but more shallow distribution in tissue than that of the CO$_2$ laser because of much higher absorption coefficient. The increase of repetition rate does not much affect on temperature rise because these laser modalities have much shorter heat diffusion time than the temporal length of each off-pulse. This model works as a tool to understand the photothermal effect in the laser-tissue interaction.

• KIEE International Transactions on Electrophysics and Applications
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• 제5C권4호
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• pp.152-154
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• 2005

We demonstrate a simple $CO_2$ laser by controlling firing angle of a TRIAC switch in ac power line. The power supply for our laser system switches the voltage of the AC power line (60Hz) directly. The power supply does not need elements such as a rectifier bridge, energy-storage capacitors, or a current-limiting resistor in the discharge circuit. In order to control the laser output power, the pulse repetition rate is adjusted up to 60Hz and the firing angle of TRIAC gate is varied from $45^{circ}$ to $135^{circ}$. A ZCS(Zero Crossing Switch) circuit and a PIC one-chip microprocessor are used to control the gate signal of the TRIAC precisely. The maximum laser output of 40W is obtained at a total pressure of 18 Torr, a pulse repetition rate of 60Hz, and a TRAIC gate firing angle of $90^{circ}$.