• Medical Lasers
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• 제9권2호
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• pp.190-193
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• 2020

A 45-year-old Korean male with laryngotracheal papilloma was treated using a 532-nm diode laser at six watts with a pulse width of 25 milliseconds. Two months after the laser treatment, the resected region was well-healed without significant scar contracture. This outcome suggests that a 532-nm diode laser can be a safe and effective treatment for laryngotracheal papilloma.

• Tribology and Lubricants
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• 제19권2호
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• pp.102-108
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• 2003

The height of laser bumps has been considered as the limit of the minimum flying height in the contact start-stop (CSS) of hard disk drives. In this paper, tribological interactions at flying height under laser bumps are investigated in a spin stand for development of ultra-low flying head-disk interface. With the reduction of the spinning speed in a spin stand, the flying height is decreased under the height of laser bumps and, then, head-disk interactions are investigated using AE and stiction/friction signals. During seek tests and 20000 cycle-sweep tests, AE and stiction/friction signals are not significantly changed and there are no catastrophic failures of head-disk interface. Bearing analysis and AFM analysis show that there are signs of wear and plastic deformation on the disks. It is suggested that flying height could be as low as and, sometimes, lower than laser bump height.

• 산업경영시스템학회지
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• 제34권3호
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• pp.35-40
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• 2011

5-axis laser cutting has great advantages when it is applied to three dimensional machining requiring high cutting quality. For developing 5-axis CNC laser cutting systems, however, many problems such as rotating a laser head or a working table, 5-axis servo-control mechanism, tool path generation and post-processing, and collision avoidance between a laser head and a work-piece should be solved. In this paper, we deal with developing a motion simulator for 5-axis laser cutting machine with a nutating cutting head whose rotational axis is in an inclined plane. Two essential modules such as post-processor and cutting motion simulator was developed based on a commercial 3D CAD of UG-NX. The developed system was applied to three dimensional cutting products and showed the validity of the developed methods.

• International Journal of Korean Welding Society
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• 제3권1호
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• pp.17-22
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• 2003

During the laser welding, weldments are suddenly heated and cooled by laser beam of high density energy. This phenomenon gives an occasion to complex welding residual stresses, which have a great influence on structural instability, in laser welds. However, relevant researches on this field are not sufficient until now and residual stress measurements have experimental and practical limitations. From these reasons, a numerical simulation may be attractive in order to solve the residual stress problem. For clarifying the distribution of heat and welding residual stresses in laser welds with the nail-head shape, authors conduct the finite element analysis (two-dimensional unstationary heat conduction & thermal elastic and plastic analysis). From the results, we can confirm the stress concentration occurs at the place of melting line shape changed in laser welds with the nail-head shape.

• 대한두경부종양학회지
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• 제22권2호
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• pp.175-178
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• 2006

Pulsed dye laser(PDL) is originally designed for the treatment of vascular lesions but also effective in improving the quality and appearance of surgical scars. Recently, 595nm Pulsed dye laser(V-beam laser), which has the advantage of deeper tissue penetration and lesser amount of purpura, is spotlighted as a new option for the treatment of surgical scar. The authors treated a surgical scar of a female patient with V-beam laser for 3 times between 4 and 12 weeks after surgery. Subjective satisfaction was improved with visual analogue scale (VAS) and objective improvements were found in parameters of vascularity, pliability and height with Vancouver Scar Scale(VSS). We report the effectiveness of V-beam laser in surgical scar of Asian patient and plan the prospective study with larger scale.

• 한국기계가공학회지
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• 제21권1호
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• pp.90-94
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• 2022

Metal 3D-printing technology enables the manufacture of complex features or internal structures, which is not possible in fabrication by conventional cutting methods. The most successful types of metal 3D printing have been powder bed diffusion and directed energy deposition, which use laser heads exploiting high-power laser sintering metal powder. In this study, a cost-effective optical design was proposed for a 2-kW-level fiber laser head. Only two commercial lenses, a beamsplitter and a window, are used in the laser head, satisfying the technological requirements. According to the optical design, the spot size was 2.54 mm, and the stand-off distance from the laser head was 295 mm. The intensity distribution was Gaussian. Thus, smooth power sintering was possible without any laser spot marks. Monte Carlo analysis was employed to verify the consistency of the optical performance under conventional assembly tolerance.

• 정보저장시스템학회논문집
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• 제7권1호
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• pp.36-41
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• 2011

The micro laser module was designed and prepared to deliver the light to the HAMR head. It consists of laser diode, photo diode and actuator to realize stable light delivery even though the head is fluctuated during the disk rotation. The optical evaluation was carried out with the actual distance between the light source and HAMR head with a range of reflectivity and it was found that the incident angle could be controlled within ${\pm}0.125^{\circ}$ to maintain same intensity into the HAMR head. It was also confirmed that the designed micro laser module is thermally stable without any severe effect on the magnetic head.

• Medical Lasers
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• 제8권1호
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• pp.39-42
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• 2019

A 50-year-old Korean female with oral erythro-leukoplakia was treated using a 532-nm Diode laser at 6 Watts with a pulsed width of 25 milliseconds. After two months following the laser treatment, the resected region was well-healed without any significant scar contracture. We suggest that the use of the 532-nm Diode laser can be a safe and effective treatment modality for patients suffering from oral leukoplakia.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 춘계학술대회 논문집
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• pp.269-273
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• 2003

During the laser welding, weldments are suddenly heated by laser beam and cooled. This phenomenon gives occasion to complex welding residual stresses, which have a great influence on structural instability strength, in laser welds. However, a relevant research on this field is not sufficient until present and residual stress measurements have experimental and practical limitations. For these reasons a numerical simulation may be attractive in order to solve the residual stress problem. In order to determine the distribution of heat and welding residual stresses in laser welds with the nail-head shape, authors conduct the finite element analysis (two-dimensional unstationary heat conduction & thermal elasto-plastic analysis). From the result of this study, we can confirm the stress concentration is occurred at the place of melting line shape changed in laser welds with the nail-head shape.

• 대한두경부종양학회지
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• 제12권2호
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• pp.201-205
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• 1996

이상의 성적에서 레이저 성대 절제술은 초기 성문암종에 대한 일차 치료법으로 유용하다고 생각되었으며, 일차 절제가 가장 중요하고 그후 성대를 포함한 전체 후두점막에 대하여 주기적으로 현수후두경하에 수술현미경을 이용한 추적관찰과 원격전이 및 이차암의 발생 유무에 대하여 적극적인 추적검사가 필요할 것으로 사료된다.