• Medical Lasers
• /
• v.9 no.2
• /
• pp.190-193
• /
• 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
• /
• v.19 no.2
• /
• pp.102-108
• /
• 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.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.34 no.3
• /
• pp.35-40
• /
• 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
• /
• v.3 no.1
• /
• pp.17-22
• /
• 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.

• Korean Journal of Head & Neck Oncology
• /
• v.22 no.2
• /
• pp.175-178
• /
• 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.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.21 no.1
• /
• pp.90-94
• /
• 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.

• Transactions of the Society of Information Storage Systems
• /
• v.7 no.1
• /
• pp.36-41
• /
• 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
• /
• v.8 no.1
• /
• pp.39-42
• /
• 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.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2003.05a
• /
• pp.269-273
• /
• 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.

• Korean Journal of Head & Neck Oncology
• /
• v.12 no.2
• /
• pp.201-205
• /
• 1996

Early detection of glottic cancer, facilitated by rigid telescopes or flexible fiberoptic laryngoscope in addition to sparse true vocal cord lymphatics, makes this a highly curable tumor in its early stage. Early glottic cancer has a high cure rate with only radiotherapy or conservative surgery. However complications such as mucositis with radiotherapy and voice complications with conservative surgery has raised recent interest in endolaryngeal laser cordectomy. Laser cordectomy can preserve phonatory function and avoid the complications such as mucositis of radiotherapy. To determine the effectiveness of laser cordectomy, the authors made a two year retrospective study of 23 early glottic cancer cases. Fourteen cases(60.9%) who underwent 1 to 3 endoscopic laser cordectomy with KTP-532 laser were cured with this procedure alone. Seven cases needed an additional radiotherapy and three cases needed therapy with salvage operation. We conclude that the endoscopic laser surgery is a good strategy for the properly selected glottic cancer.