• 대한기관식도과학회지
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• 제16권1호
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• pp.20-26
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• 2010

Transoral $CO_2$ Laser Microsurgery of glottic Carcinoma is replacing external approaches. The qualify of life after surgery for laryngeal cancer may be as important as complete resection of the tumor for patient. Transoral $CO_2$ laser cordectomy for the management of early laryngeal cancer has advantages with regard to oncological results, preservation of laryngeal functions, morbidity and cost in comparison to those of open surgery or radiation therapy. Moreover, transoral laser surgery can be a useful choice as a salvage surgery in radiation therapy failed early glottic cancer. A classification of laryngeal endoscopic cordectomies which included eight different types was described by the European laryngological Society in 2000. We will also introduce type VI which was newly proposed recently.

• 한국레이저가공학회:학술대회논문집
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• 한국레이저가공학회 2002년도 춘계학술발표대회 논문개요집
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• pp.65-70
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• 2002

• 한국광학회:학술대회논문집
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• 한국광학회 1990년도 제5회 파동 및 레이저 학술발표회 5th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.45-48
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• 1990

CO2 laser beam was focused by a ZnSe lens onto the center of the occlusal surface f extracted lower molars. K-type thermocouple was contacted with the pulp chamber and the changes of temperature in the 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.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권11호
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• pp.730-734
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• 1999

In this study, it is the purpose to develope a cheap and compact repetitively pulsed $CO_2$ laser with pulse repetition rate range of 180 Hz. We used a SCR switched power supply as a high voltage pulsed supply, which is cheap and simple comparing to others. PIC one-chip microprocessor was used for precise control of a laser power supply on the control part. And the laser cavity was fabricated as an axial and water cooled type. The laser performance characteristics as various parameters, such as pulse repetition rate and gas pressure have been investigated. The experiment was done under the condition of total pressure of $CO_2, N_2$ and He from 4 Torr to 16 Torr and pulse repetition rate from 4 Hz to 180 Hz. As a result, the maximum average output was about 19.6W at the total pressure of 12 Torr and the pulse repetition rate of 180Hz.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.1015-1016
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• 2006

The important parameters deciding the fluctuation of Accumulation style surgical operation of ventriculus laser beam are smoothing capacitor, frequency and he characteristics of laser resonator. In this thesis, we control the fluctuation of medical $CO_2C$ laser in realtime by changing Duty-Ratio of IGBT and switching frequency with fixed the smoothing capacitor to improve the fluctuation of laser beam. We detect the light on laser resonator using a CdS photo sensor to improve ripple factor of laser beam and feedback fluctuated signals refined by a band pass filter into the control circuit to stabilize fluctuation actively. There is much to be desired in the realtime controlling technique of the light on Accumulation style surgical operation of ventriculus laser discharge tube in electrical signal. We propose switching control technique with microprocessor and photo sensing technique by controlling switch devices optimum operation and feedback signals detected by a photo sensor into the laser power supply in order to improve ripple factor of the $CO_2$ laser beam.

• 한국생산제조학회지
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• 제21권4호
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• pp.644-650
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• 2012

This paper show the 2kW fiber laser cutting properties of SS400. The study was comparison of traditional 4kW $CO_2$ Laser cutting and 2kW Fiber laser cutting characteristics for the application of Industrial 2D Laser Cutting Machine. The laser used in this investigation was an IPG YLU-2000 multi-mode Ytterbium Fiber machine with a maximum power of 2000W and a wave length of 1070 nm. The laser was used in its Continuous Wave (CW) mode with an approximately top hat beam intensity distribution. Fiber laser high quality cuts at a large range of speeds (ranging from 2000 to 3800 mm/min) which has been obtained for the 2.3mm Sheet of SS400. 2kW power Fiber laser cut was able to max. 20mm sheets of SS400 (speed range from 650 to 850 mm/min). Fiber laser cutting used in conventional hole nozzle could cut 12mm SS400 but used in special dual cutting nozzle could cut 20mm SS400.

• 대한기관식도과학회지
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• 제13권2호
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• pp.45-49
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• 2007

Background and Objective : Laryngeal Papillomatosis (LP) is the most common benign neoplasm of the larynx, but it tend to recur and it makes eradicating difficult. Meticulous $CO_2$ laser excision has been the most effective treatment to date. This article analyzes the clinical feature and therapeutic results of 42 LP patients who were undergone $CO_2$ laser excision. Methods : Forty two patients with recurrent LP were treated with $CO_2$ laser. And their medical records were reviewed retrospectively. Demographics, chief complaints at onset, initial distribution of papillomas, number of operations performed on each patient, and current results were evaluated. Results : Male in their twenties and forties are dominant in number in patient number. Most common site was anterior one thirds (69%) of glottis area (86%). LP recurred in 17 cases (40%), and in 4 cases, the lesion extended over the original margin. Patients were undergone surgery $1.62{\pm}0.87$ times, $2.53{\pm}0.72$ in recurred cases. Mean relapsing time was 6 momths (from 1momth to 8years). Ant. laryngeal web occurred in 2 cases (4.8%) and 1 case was combined with squamous cell carcinoma. Conclusion : Meticulously performed $CO_2$ laser excision can achieve significant voice and airway improvement and clinical cures. The $CO_2$ laser through microdirect laryngoscopy allows more precise and bloodless removal of papillomas.

• Journal of Welding and Joining
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• 제7권4호
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• pp.12-21
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• 1989

Laser beam welding parameters have experimentally investigated, using a continuous wave 3kW $CO_2$ laser with the various travel speeds, beam mode and laser beam power in low carbon steels. An optimum position of focus and the effect of shielding gas on penetration depth with varying the flow range of 0.5 to 5.1m/min have been combined to investigate the effect of laser power and travel speed on penetration depth and bead width. It is found that the optimum position of focus in 3kW class laser is 0.5 to 1.5mm below the surface of the material. The flow rate of shielding gas affects the penetration depth and He is more effective than Ar. The penetration depth in laser welds of low carbon steels is between two and four times of the bead width. Laser beam welding of butt joints in 2mm thick carbon steel has been carried out to establish a weldability lobe. The lobe indicating acceptable welding conditions is introduced.

• 한국기계가공학회지
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• 제18권5호
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• pp.74-81
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• 2019

This study reports the CW $CO_2$ laser scribing of soda lime glass. In this study, scribing experiments are carried out at different laser powers, scan speeds, and focal positions to investigate the effect of the process parameters on the interaction characteristics between a laser beam and glass. In particular, the interaction characteristics are analyzed and described with the input laser energy per unit length. According to the experimental results, the damage threshold for the glass surface was found to exist between 0.072 and 0.08 J/mm. The input laser energy in this region induced partial melting of the surface and grain-shaped cracks. These cracks tended to increase as the input laser energy increased. At the laser input energy larger than 1 J/mm, a huge crack propagating along the scan direction was produced, and the volume below the scribed area was fully melted. The growth of this crack finally resulted in the complete cutting of the glass at the input laser energy above 8 J/mm. It was found that both the width and depth of the scribed line increased with increasing input laser energy. For the beam focusing at the rear surface, the width of the scribed line varied irregularly. This could be ascribed to the increased asymmetry of the beam intensity distribution when the laser beam was focused at the rear surface. Under this condition, a large burr was only produced on one side of the scribed line.

• 한국광학회지
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• 제15권4호
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• pp.337-342
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• 2004

본 연구에서는 opto-Hertzian 효과를 이용하여 고주파 여기식 슬랩형 $CO_2$ 레이저의 출력을 안정화하였다. 슬랩레이저 공진기속의 복사선 세기가 변화할 때 opto-Hertzian 효과에 의해서 공진기의 방전 임피던스도 함께 변화한다. 이에 따라 공진기로 입사 또는 반사되는 고주파 에너지 값도 변화한다. 이 같은 변화를 결합 루프를 통해 검출하여 고주파 성분을 제거한 후 록인 안정기에서 발생시킨 오차신호를 기준신호로 사용하여 슬랩 레이저의 출력을 안정화하였다. 본 방법으로 안정화된 레이저의 출력 변동률이 0.2%로 개선됨을 확인하였다.