• Nuclear Engineering and Technology
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• v.33 no.2
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• pp.175-183
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• 2001

Various welding processes are now available for end cap closure of nuclear fuel element such as TG(Tungsten Inert Gas) welding, magnetic resistance welding and laser welding. Even though the resistance and TIG welding processes are widely used for manufacturing commercial fuel elements, they can not be recommended for the remote seal welding of a fuel element at a hot cell facility due to the complexity of electrode alignment, difficulity in the replacement of parts in the remote manner and a large heat input for a thin sheath. Therefore, the Nd:YAG laser system using optical fiber transmission was selected for Zircaloy-4 end cap welding inside hot cell. The laser welding apparatus was developed using a pulsed Nd:YAG laser of 500 watt average power with optical fiber transmission. The weldability of laser welding was satisfactory with respect to the microstructures and mechanical properties comparing with TIG and resistance welding. The optimum operation processes of laser welding and the optical fiber transmission system for hot cell operation in a remote manner have been developed The effects of irradiation on the properties of the laser apparatus were also being studied.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.4
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• pp.169-172
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• 2003

Silicon nanocrystalline thin films on p-type (100) silicon substrate have been fabricated by pulsed laser deposition technique using a Nd:YAG laser with the wavelength of 355, 532, and 1064 nm. The base vacuum in the chamber was down to $10^-6$ Torr and the laser energy densities were 1.0~3.0 J/$\textrm{cm}^2$ After deposition, silicon nanocrystalline thin films have been annealed at nitrogen gas. Strong Blue and green luminescence from silicon nanocrystalline thin films have been observed at room temperature by photoluminescence and its peak energies shift to green when the wavelength is increased from 355 to 1064 nm.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.1
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• pp.75-81
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• 2014

Laser beam machining has been known as efficient for glass micromachining. It is usually used the ultra-short pulsed laser which is time-consuming and uneconomic process. In order to use economic and powerful long pulsed laser, indirect processing called laser-induced backside wet etching (LIBWE) is good alternative method. In this paper, micromachining of glass using Nd:YAG laser with nanosecond pulsed beam has been attempted. In order to improve shape accuracy, combined processing with magnetic stirrer has been widely used. Magnetic stirrer acts to circulate the solution and remove the bubble but it is not suitable for deep hole machining. To get better effect, ultrasonic vibration was applied for improving shape accuracy.

• Journal of Oral Medicine and Pain
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• v.22 no.2
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• pp.261-282
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• 1997

This study was undertaken to compare and investigate the wound healing process following Nd:YAG laser wounds and scalpel incisions of the rat tongue dorsal mucosa. Laser wounds were made parallel on the right side of tongue dorsum and scalpel incisions were made on the left side with 5mm length, respectively Visual inspection and immunohistochemistry with CD44 antibody after immediately, 6 hours, 1 day, 2, 4, 7, 11, 21 days after surgery were carried out. The results were as follows : 1. There was macroscopically no treat difference between laser wounds and scalpel incisions. 2. Laser wounds appeared as dry, bloodless and irregular grooves with carbonization and whitening of superficial tissues compared to sharp, straight and bleeding incisions using scalpel. 3. In the epithelium of rat tongue mucosa, CD44 expression in healing laser wounds and scalpel incisions were similar. 4. In the lamina propria and muscle layer, CD44 expression in healing laser wounds gradually increased earlier and decreased faster than scalpel incisions. Conclusively, it is suggested that pulsed Nd:YAG laser has more beneficial effect on the healing of wounded oral mucosa than scalpel in knew of CD44 expression.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1696-1698
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• 1998

Pulsed Nd:YAG laser using Nd:YAG crystal operates stably in the thermal conductivity, mechanical, optical condition. That is used broadly in material processings because of easy reaction to the materials, and the maintenance is very easy because of lamp excitation. In these material processings, power dinsity control is very important to improve processing technology. Power density is controled by inductance and capacitance or repetition rate. Therefore we are going to control laser power density as One-Chip Microprocessor(PIC16C55) and 8051. We have been experimented at the pulse repetition rate range of 10pps to 60pps(pulse per second).

• Proceedings of the KWS Conference
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• 1997.05a
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• pp.99-101
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• 1997

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.133-133
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• 2003

• Proceedings of the Korean Society of Laser Processing Conference
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• 2005.06a
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• pp.45-47
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• 2005

• Maxillofacial Plastic and Reconstructive Surgery
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• v.22 no.1
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• pp.33-42
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• 2000

The purpose of this study was to compare the wound healing process after skin incision using scalpel, $CO_2$ laser and pulsed Nd:YAG laser in rats. After skin on the back was incised 3 cm long, rats were sacrificed at 1, 3, 7, 14, 21 and 28 days. Macroscopic, histologic and immunohistochemical examinations using the collagen type IV and the CD34 antibodies which are necessary to the forming process of new capillary were performed. Results obtained were as follows ; Macroscopically the initial wound healing of the laser group was about $1{\sim}2$ weeks slower than that of the scalpel group. There weren't however any remarkable differences in all groups in 4 weeks after incision. By histologic finding, acute inflammatory cells were more prominent during the initial wound healing in the scalpel group than in the other groups. Epithelialization started in the order of scalpel, $CO_2$ and Nd:YAG laser group after skin incision. By the Masson's trichrome stain, collagen synthesis in the Nd:YAG laser group was more slowly initiated than in the other groups. But it was completed at the $3{\sim}4$ weeks in all groups. Immunohistochemically, collagen type IV and CD34 expression were markedly increased at 2 weeks in the scalpel and $CO_2$ laser group. Meanwhile, in the Nd:YAG laser group, these reactions were observed later tan the other groups. Collagen type IV and CD34 expression were decreased in all groups after 4 weeks. These results suggest that $CO_2$ and Nd:YAG laser showed similar healing process compared with scalpel and a potential substitute for scalpel in skin incision.

• Laser Solutions
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• v.8 no.2
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• pp.13-20
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• 2005

Weldability is largely dependent on the phase evolution and the microstructure of the weld. For the weldability of the $Cu_{54}Ni_6Zr_{22}Ti_{18}$ bulk metallic glass, the crystallization affects the sensitivity of the weld to the brittle failure. In order to suppress the irreversible crystallization, Nd:YAG laser welding was chosen. The pulsed Nd:YAG laser was irradiated onto the BMG plate and the effects of the pulse shape [peak power intensity and pulse duration time] on the crystallinity were evaluated.