• 대한치과보철학회지
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• 제27권2호
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• pp.155-172
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• 1989

The purpose of this study is to measure the bonding strength at the enamel and dentin of extracted bovine incisors when they are irradiated by W Nd: YAG, EoQ Nd: YAG, and CW $CO_2$ laser, etched and then attached by composite resin. The laser-irradiated surface, the etched surface after the laser-irradiation and the interface of the treated surface and resin are observed by using scanning electron microscope. The NP Nd:YAG laser is used at the peam power of 207 KW. The EOQ Nd: YAG laser is used at the peak power of 1.15Mk. The CW $CO_2$ laser is used at the energy output of 5W and 10W in enamel; in dentin, at the energy output of 2W. The obtained results were as follows: 1. The shear bond strength of enamel decreased in the following order: EOQ Nd:YAG laser group, NP Nd:YAG laser group, CW $CO_2$ laser groups, unlased group. The unlased group showed a significant difference from EOQ Nd:YAG laser group (P<0.01), NP Nd:YAG laser group (P<0.05), but no significant difference from CW $CO_2$ laser group (P>0.05). 2. The shear bond strength of dentin decreased in the following order: CW $CO_2$ laser group, NP Nd:YAG laser group, unlased group, EOQ Nd:YAG laser group. The unlased group showed a significant difference from CW $CO_2$ laser group (P<0.01), but no significant difference from Nd:YAG laser groups (P>0.05). 3. The scanning electron microscope of enamel revealed irregular microcrack and pore at the surface in the NP Nd:YAG laser group and CW $CO_2$ laser group, but the crackless flat surface in the EOQ Nd:YAG laser group. 4. The scanning electron microscope of dentin revealed obstruction of in most of dentinal tubule and decrease of diameter. 5. The scanning electron microscope of the interface of resin and enamel revealed prominent penetration of resin tag in the EOQ Nd:YAG laser group.

• Journal of Welding and Joining
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• 제21권7호
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• pp.34-41
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• 2003

Weld quality monitoring and seam tracking along the butt-joint lengthwise to the tube axis are studied. The material of tube is 60kg/$\textrm{mm}^2$ grade steel sheet, and the longitudinal butt-joint is shaped by 2 roll bending machine. The tube with a thickness of 1.5mm, diameter of 105.4mm and length of 2000mm is successfully obtained by the $CO_2$ laser welding system equipped with a seam tracker and plasma sensor. Experimental results show that the developed welding system can be used for the precision seam tracking and the real-time monitoring of weld quality, and the laser welded tube can be used for car body md component after tubular hydroforming.

• International Journal of Precision Engineering and Manufacturing
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• 제6권3호
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• pp.19-23
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• 2005

To minimize the weld defect in manufacturing of the welded tube by using $CO_2$ laser, the monitoring of the welding quality and the seam tracking along the butt-joint lengthwise to the tube axis are studied. The longitudinal butt-joint is shaped from $60kgf/mm^2$ grade steel sheet by 2 roll bending method, and welded by the $CO_2$ laser welding system equipped with the seam tracker and plasma sensor. The laser welded tube has the thickness of 1.5mm, diameter of 105.4mm and length of 2000mm. The precise positioning of the laser beam on the butt-joint to be assembled is obtained within $200{\mu}m$ by the laser vision sensor. The artificial defects in the butt-joint are well observed by the signal of plasma intensity measured from the plasma sensor of UV wavelength range within 400nm. The developed $CO_2$ laser tube welding system has the function of the precision seam tracking and the real-time monitoring of the welding quality. In conclusion, the laser welded tube can be used for manufacturing of automobile chassis and components after hydro-forming.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.55-57
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• 2007

$CO_2$ laser sees that is most suitable to get this effect through minimum formation damage and advantage that is root enemy of effect that happen in minimum cellular tissue depth of 0.1mm is stable living body organization or internal organs institution. Formation damage by ten can be related in formation's kind or energy density, length of evaporation time. If shorten evaporation time, surroundings cellular thermal damage 200 - because happen within 400ums laser beam in rain focus sacred ground surroundings cellular, tissue without vitiation me by evaporation Poe of very small floor as is clean steam can. Application is possible to vulva cuticle cousins by a paternal aunt quantity, uterine cancer, cuticle tumor by laser system that $CO_2$ laser gets into standard in obstetrics and gynecology application. Because effect that super pulse output is ten enemies of laser if uniformity one pulse durations are short almost is decreased, most of all pulse module special quality of pulse style $CO_2$ laser for obstetrics and gynecology mode stabilization by weight very, in this research to get into short pulse duration and higher frequency density, do switching by high frequency in DC-DC Converter output DC's ripple high frequency to be changed, high frequency done current ripple amount of condenser for output filter greatly reduce can. Ripple of output approximately to Zero realization applying possible inductor realization through a special quality experiment do.

• 한국레이저가공학회지
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• 제18권3호
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• pp.14-19
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• 2015

A helical fabricating method using $CO_2$ laser was utilized for producing cone-shaped structure on a silica substrate. Output power and the number of scanning radiation were modified in order to control the structure. The experiment shows that the depth and width of cone-shape were increased with higher output power of the laser and the number of scanning. We demonstrate fabrication of multidirectional side-firing optical fiber with diameter of 440 um using the $CO_2$ laser fabrication technique.

• 한국세라믹학회지
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• 제37권1호
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• pp.57-62
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• 2000

In this study, an attempt was made to demonstrate the possibility of using laser scribing method in manufacturing the barrier ribs of plasma display panel. The scribing with a CO2 laser was conducted on the green tape produced by the doctor blade tape casting method. Among the processing parameters, the quenching gas pressure, shape of mask, and laser power were found to affect the depth and angle of the scibed barrier ribs.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(5)
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• pp.257-260
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• 2002

In this paper, the circuit of AC Choppers for $CO_2$laser Power Supply are proposed and investigated. IGBT-controlled ac voltage regulators, operating at high frequency chopping mode. Chopping-to-supply duty ratio plays an important role in terms of laser output. Laser input energy is varied by controlling the leakage transfomer used with the proposed system. This improved circuit employs a 3 electrode-type and Ring Blower. This improved circuit system has many advantages compared with the conventional SMPS such as simple design requirment, easy implementation, high reliability, low switching loss, and consequently high efficiency. As a result, the maximun output was 16W at duty-ratio of 92%, total gas mixture of $CO_2$: $N_2$: He = 1 : 9 : 15, total pressure of 15torr.

• 한국광학회지
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• 제14권4호
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• pp.406-412
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• 2003

고주파 여기 방식의 슬랩 도파관 $CO_2$ 레이저를 제작하고 그 특성을 조사하였다. 레이저 이득을 얻기 위한 고주파 방전구간의 크기는 2${\times}$40${\times}$400mm이고, 레이저 공진기는 볼록거울과 오목거울을 사용하여 positive branch형태의 불안정 공진기를 사용하였다. 고주파 여기 주파수는 123 MHz를 사용하였고, 가스의 혼합 비율은 $CO_2$:$N_2$:He를 각각 1:1:3으로 사용하였다. 공진기의 가스 압력이 40 ton,고주파 입력파워 900 W에서 70.8 W의 출력을 얻었으며, 이때 레이저의 효율은 9.2%이다.

• 한국레이저가공학회지
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• 제1권1호
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• pp.18-23
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• 1998

A Study on microstructural changes of sensitized Alloy 600 which was rapidly solidified by a $CO_2$ laser beam was conducted using microscopic equipments such as SEM and TEM. Dissolution of Cr-rich carbides and resultant Cr recovery on the grain boundaries occurred in the heat affected zone (HZA). The microstructure of the laser melted zone (LMZ) having epitaxially solidified from the HAZ was mainly celluar-dendritic with the 〈100〉 crystallographic direction of growth. The Cr concentration was observed to increase along the cell bondaries, and tiny particles were distributed along the cell walls with tangled dislocations around them. Cr-rich carbides had been completely melted by the high density of a laser beam, and were not re-precipitated during the matrix solidification due to a fast cooling rate in the LMZ.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.667-671
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• 1989

The CO laser is one of powerful light source for laser magnetic resonance spectroscopy in the mid-infrared region of the spectrum because of its wideband operational characteristics. In this work, a liquid nitrogen cooled cw CO laser is developed to allow broad-band operation from 5 to 8 ${\mu}m$. The design details will be presented.