• 한국레이저가공학회지
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• 제10권4호
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• pp.1-6
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• 2007

This study includes the effects of shielding gas types and flow rate on Nd:YAG Laser weldability of sintered material. The types of shielding gas were evaluated for He, Ar and N2. Bending strength, porosity rate, hardness and aspect ratio testing of laser weld are carried out to evaluated the weldability. As a results, Ar gas was showed the best welding strength even it has the most porosity content on weld metal, and depend on increases the gas flow rate, it was not only got deeper penetration depth but also showed higher bending strength. Therefore we could know that bending strength is not only affect the porosity content but also melting area.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2006년도 춘계 학술대회 개요집
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• pp.248-250
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• 2006

The study on a surface transformation hardening of a rod-shaped SM45C carbon steel is carried out by using CW Nd:YAG laser. Conventionally, $CO_2$ laser has been usually used as a laser source for a transformation hardening. however, it is needed to an additional absorbent coating like a colloidal graphite owing to a lower absorbtion rate. On the other hand, no cost and post-removal process of coating is required to Nd:YAG laser, due to a higher absorbtion rate relatively. Moreover, there is a merit which is capable of building up the more flexible processing system resulted from a beam delivery through a optical fiber. In this study, we were going to recognize characteristics of a transformation hardening using a optic head with a gaussian beam distribution.

• 대한기계학회논문집A
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• 제28권4호
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• pp.481-488
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• 2004

Laser chemical vapor deposition can be used as a new approach for a rapid prototyping technique. The purpose of the study is to fabricate several 3-dimensional objects that are relatively simple as well as to find the characteristics of SiC rod growth that is the first step in developing a new rapid prototyping technique with laser chemical vapor deposition. In the study, SiC rods were generated with varying precursor pressure for 5 minutes. Deposition rates with varying precursor pressure, shapes of rods, surface roughness and component organization were investigated, in particular. Finally, several simple objects like a branch or a propeller were successfully fabricated using laser chemical vapor deposition.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 추계학술대회 논문집
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• pp.85-89
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• 2002

This paper used the Laser Speckle Interferometry to present the strain analysis of Nd:YAG Laser welding zone. Previous TIG welding to sheet plate, which welds only high-skilled engineer, produces residual stress nearby welding zone due to thermal effect. However, Laser welding makes sheet pate welding easy and thermal effect minimum. Thermal effect zone is measured by strain analysis of the laser-welding zone by ESPI under tensile testing of sheet plate welded by Nd:YAG laser. The ESPI results, which compared with strain gage method, are agreed within error 3 %.

• Journal of Welding and Joining
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• 제22권1호
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• pp.58-64
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• 2004

The control of the weld bead shape is important in laser welding of the small parts. The effects of laser welding parameters on the weld bead shape in the pulsed Nd:YAG laser welding of STS 304L material were investigated. Shielding gas type, flow rate, pumping voltage, pulse frequency, pulse width, focal position and overlap distance were selected as laser welding parameters. Experiments were designed and conducted using the Taguchi method which was a statistical experimental method. The weld bead width, penetration, area and aspect ratio were measured and analysed as the weld bead shape properties and the welding parameters were optimized to maximize the weld aspect ratio. Weld aspect ratio were greatly affected by the pulse width, pumping voltage and pulse frequency, and somewhat by the overlap distance, and little by the shielding gas type, flow rate and focal position. A confirmation experiment were conducted using the optimized welding parameters.

• Current Optics and Photonics
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• 제3권3호
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• pp.243-247
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• 2019

We have developed a compact, wavelength-selectable, Q-switched Nd:YAG laser at mid ultraviolet for chemical warfare agent detection. The fundamental wave at 1064 nm is delivered by a pulsed solid state laser incorporating with a square-type Nd:YAG rod in a resonator closed by two crossed Porro prisms for environmental reliability. The output energy at 213 nm ($5{\omega}$) and 266 nm ($4{\omega}$) by ${\chi}^{(2)}$ process in the sequentially disposed BBO crystals are measured to be 6.8 mJ and 15.1 mJ, respectively. The output wavelength is selected for $5{\omega}$ and $4{\omega}$ by a motorized wavelength switch. The energy ratio of the $5{\omega}$ to the $4{\omega}$ is varied from 0.05 to 0.85 by controlling the phase matching temperature of the nonlinear crystal for sum-frequency generation without change of the output pulse parameters.

• Medical Lasers
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• 제10권3호
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• pp.185-188
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• 2021

Onychomycosis is the most common disease of the nail, with a worldwide prevalence of 5.5%. It causes local pain, paresthesia, and cosmetic problems and decreases the patients' quality of life. Conventional treatments include the administration of topical and systemic agents. However, factors such as subungual hyperkeratosis and biofilm formation may affect the efficacy of these treatments. Moreover, side effects associated with systemic agents are a major concern for patients. Therefore, various novel treatments are being developed; among them, photodynamic therapy (PDT) and Nd:YAG laser are promising, and several studies have demonstrated the efficacy and safety of PDT and laser therapy. Here, we report the efficacy and tolerability of PDT combined with 1064-nm Nd:YAG laser therapy and topical efinaconazole for the treatment of three patients with refractory onychomycosis.

• Medical Lasers
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• 제8권1호
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• pp.32-34
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• 2019

Postinflammatory hyperpigmentation (PIH) is a reactive hypermelanosis of the skin that occurs as a result of variable inflammatory processes, such as trauma, and many inflammatory conditions. Although a range of modalities of managing PIH have been reported, the treatment of PIH is challenging. In this report, a patient with PIH was treated using picosecond-domain Nd:YAG lasers. After three sessions of 1,064-nm picosecond-domain Nd:YAG laser treatment, the patient showed almost complete improvement with no remarkable side effects or recurrence over the duration of six months. Overall, 1,064-nm picosecond-domain Nd:YAG laser can be used effectively and safely for treating pigmented lesions in the dermis, particularly PIH, in Asian patients.

• 한국재료학회지
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• 제18권3호
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• pp.113-116
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• 2008

A 532 nm Nd-YAG laser was applied to crystallize amorphous Si thin films in order to evaluate the applicability of a Nd-YAG laser to low-temperature polycrystalline Si technology. The irradiation of a green laser was controlled during the crystallization of amorphous Si thin films deposited onto glass substrates in a sophisticated process. Raman spectroscopy and UV-Visible spectrophotometry were employed to quantify the degree of crystallization in the Si thin films in terms of its optical transmission and vibrational characteristics. The effectiveness of the Nd-YAG laser is suggested as a feasible alternative that is capable of crystallizing the amorphous Si thin films.

• 한국광학회:학술대회논문집
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• 한국광학회 1997년도 Advance Program of 14th optics andquantum Electronics conference, 1997제14 회 광학 및 양자전자 학술 발표회 논문 요약집
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• pp.86-86
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• 1997