• 한국광학회지
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• 제15권4호
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• pp.343-348
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• 2004

고주파로 여기 되는 매트릭스형 도파관 이산화탄소 레이저를 개발하였다. 단위길이당 레이저 출력을 증가시키기 위하여 4개의 고주파 방전관을 2 ${\times}$ 2 형태의 매트릭스 구조로 제작하여 한개의 공진기 속에 배치하였다. 레이저 출력은 출력경으로부터 가까운 거리에서는 4개의 독립된 형태로 출력되었고, 출력경으로부터 거리가 멀어질수록 4개의 빔이 하나로 합쳐짐으로서 가우시안 모드에 가까워지는 것을 확인하였다. 레이저에 주입되는 혼합 가스압력이 45 mbar, 가스 혼합비율이 $CO_2$ : $N_2$ : He : Xe = 1 : 1 : 3 : 0.2, 고주파입력 파워가 200 W일 때 약 12 W의 광출력을 얻었다.

• Journal of Welding and Joining
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• 제24권4호
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• pp.27-31
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• 2006

Optimization of process parameters for laser-arc hybrid welding process is intrinsically sophisticated because the process has three kinds of parameters-arc, laser and hybrid welding parameters. In this paper, the relationship between weldability and several process parameters such as laser beam-arc distance, electrode height, welding current and welding speed, were investigated by the full factorial experimental design. Weld quality was evaluated by using weight of spatters which is related with the pore area. It was found that the weld quality was increased with the increases in laser beam-arc distance and welding current, and decreased with the increases in electrode height and welding speed.

• 한국레이저가공학회지
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• 제3권2호
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• pp.53-61
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• 2000

On the laser weld production line, a slight alteration of the welding condition produces many defects. The defects are monitored in real time, in order to prevent continuous occurrence of defects, reduce the loss of material, and guarantee good quality. The measurement system is produced by using three photo-diodes for detection of the plasma and spatter signal in CO$_2$ laser welding. For high speed CO$_2$ laser welding, laser tailored welded blanks for example, on-line weld quality monitoring system was developed by using fuzzy multi-feature pattern recognition. Weld qualities were classified optimal heat input, a little low heat input, low heat input, and focus misalignment, and final weld quality were classified good and bad.

• 한국광학회지
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• 제3권4호
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• pp.234-238
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• 1992

금속과 판유리를 이용한 도파관 탄산가스 레이저를 제작하고 출력특성을 조사하였다. 도파관의 길이는 50cm, 내부 단면적은 $6\times 6\ttextrm{mm}^{2}$이며 13.56MHz의 고주파로 횡여기시키는 방식이다. 가스 밀폐형으로 동작될 때 입력전력과 가스압력 변화에 의한 레이저 출력의 측정 결과 가스 분압비 $He:CO_{2}:N_{2}:Xe= 6:1:2:1$, 전체 가스압력 50Torr, 고주파 입럭전력이 180W인 조건에서 최대출력 9.5W로 발진하고 있다.

• Journal of Welding and Joining
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• 제24권2호
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• pp.71-78
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• 2006

It has been reported that good quality weld beads are not easily obtained during the $CO_2$ CW laser welding of primer coated plate. However, by introducing a small gap clearance in the lap position, the zinc vapor can escape through it and sound weld beads can be acquired. Therefore, this study examines for keyhole behavior by observing the laser-induced plasma and investigates the relation between keyhole behavior and formation of weld defect. Laser-induced plasma has accompanied with the vaporizing pressure of zinc ejecting from keyhole to surface of primer coated plate. This dynamic behavior of plasma was very unstable and this instability was closely related to the unstable motion of keyhole during laser welding. As a result of observing the composition of porosity, much of Zn element was found from inner surface of porosity. But Zn was not found from the dimple structure fractured at the weld metal. By analyzing of vaporizing element in laser welding, a component ratio of Zn was decreased by introducing a small gap clearance. Therefore we can prove that the major cause of porosity is the vaporization of primer in lap position. Mechanism of porosity-formation is that the primer vaporized from the lap position accelerates dynamic behavior of the key hole and the bubble separated from the key hole is trapped in the solidification boundary and romaines as porosity.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.659-661
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• 1989

$CO_2$ laser beam was focused a ZnSe lens onto the center of the occlusal surface of extracted lower molars. K-type thermocouple was contacted with the pulp chamber and the changes of temperature in the pulp chamber during and after the laser irradiation were measured as function of the power of laser beam, the time of laser irradiation and thickness of the sample. An empirical formula for temperature effect was derived from the measured data.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1996년도 춘계학술대회 논문집
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• pp.159-164
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• 1996

For the purpose of establishing laser welding condition(laser power, welding speed and beam focus) and of evaluating tailor welded blank for three kinds of thin steel sheets of SPCC, SK5M and SUS304 using in the thin plate structure such as automobile, train and so on. Their $CO_2$ laser weldability were primarily tested under various welding condition. SPCC and SUS304 thin sheets showed good weldability under some welding condition. But, high carbon steel sheet SK5M needs heat treatment after welding to obtain higher tensile strength and ductility of the welded joint. And next, laser welding condition. Butt-welded specimens were not nearly broken at weld bead. However, base material were ruptured in the direction of circumference. The forming depths by tailor weld bead. However, base material were ruptured in the direction of circumference. The forming depths by tailor welded blank were SPCC+SPCC=22~25mm, SUS304+SUS304=25~43mm and SK5M+SK5M=13~17mm.

• 대한기관식도과학회지
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• 제3권1호
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• pp.128-136
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• 1997

저자들은 Patau증후군에 동반된 후두연화증으로 심폐정지가 유발된 환아에서 $CO_2$레이저를 이용한 aryepiglottoplasty를 시행하여 극적인 호전을 보였기에 문헌고찰과 함께 치료경험을 보고하는 바이다.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2010년도 임시총회 및 하계학술연구발표회
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• pp.40-40
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• 2010

• 한국레이저가공학회지
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• 제2권2호
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• pp.34-41
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• 1999

A RS840 $CO_2$laser and a powder auto-feeding apparatus have been used to deposit single tracks of Ni-base superalloy on low carbon steel. In this paper, the effects of laser cladding parameters on clad geometry, dilution and microhardness are studied. As a results, the w/h ratio of the clad layer increases with decreasing powder feed rate and increasing laser scan speed. Increase of powder density and decrease of specific energy have little effect on dilution. It was found that the clad layer of the highest hardness has a structure in which fine and leaf like phases are dispersed in ${\gamma}$Ni matrix.