• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.8
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• pp.736-741
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• 2007

Low level laser therapy has various therapy effects, This paper performed the basic study for fabricating the low level laser therapy apparatus, and one of the goals of this paper was to make this apparatus used handily. The apparatus has been fabricated using the laser diode and microprocessor unit. The apparatus used a 660nm, 785nm and 850nm laser diode for laser medical therapy and was designed for a pulse width modulation type to increase stimulation effects. To raise the stimulus effect of the human body, the optical irradiation frequency could be set up. In result, the $1{\sim}10\;Hz$ irradiation frequency could be controlled stably.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.11
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• pp.1379-1389
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• 1999

A new technique for control of size and shape of flame-made particles is Introduced. The characteristic sintering time can be controlled Independently of collision time by heating the particles with irradiation of laser because the sintering time strongly depends on temperature. A coflow oxy-hydrogen diffusion flame burner was used for $SiCl_4$ conversion to silica particle. Nanometer sized aggregates irradiated by a high power CW $CO_2$ laser beam were rapidly heated up to high temperatures and then were sintered to approach volume-equivalent spheres. The sphere collides much slower than the aggregate, which results in reduction of sizes of particles maintaining spherical shape. Light scattering of Ar ion laser and TEM observation using a local sampling device were used to confirm the above effects. When the $CO_2$ laser was irradiated at low position from the burner surface, particle generation due to gas absorption of laser beam occurred and thus scattering intensity increased with $CO_2$ laser power. At high irradiation position, scattering intensity decreased with $CO_2$ laser power and TEM image showed a clear mark of evaporation and recondensation of particles for high $CO_2$ laser power. When the laser was irradiated between the above two positions where small aggregates exist, average size of spherical particles obviously decreased to 58% of those without $CO_2$ laser irradiation with the spherical shape. Even for increased carrier gas flow rate by a factor of three, TEM photograph also revealed considerable reduction of particle size.

• Biomedical Science Letters
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• v.14 no.3
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• pp.167-172
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• 2008

We compared the clinical efficacy of LED therapy using 880 nm and 630 nm LED to test collagen accumulations in subcutaneous tissue of mouse after LED irradiation by measuring the quantity of collagen. 880 nm and 630 nm LED was irradiated on the back of ICR mouse given at $10.8J/cm^2$ followed for 30 minutes everyday for 5 weeks. Histological observation was performed by Hematoxylin & Eosin staining and Masson's Trichrome collagen staining. We also used Sircol soluble collagen assay kit for measuring the amounts of collagen in the mouse skin tissue after 1, 3, and 5 weeks post LED irradiation, respectively. Collagen generation was found at subcutaneous tissue, and the quantity of collagen in 880 nm LED group had grown more than that of 630 nm LED group at 5 weeks follow-up later. About 75% more efficacies for collagen generation were found in the group of 5th week of 880nm LED irradiation. The efficacy of 880nm LED could be more useful than 630 nm LED for synthesizing collagens in mouse subcutaneous tissue as time followed.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.625-626
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• 2008

The magnetic domain-refining techniques such as ball scratching, laser irradiation and plasma have been developed to reduce the domain wall spacing and thus iron losses in Fe-3%Si grain-oriented silicon steels. In view point of magnetic properties, it was supposed that the locally residual stresses change the magnetoelastic energy of the material and thus the spacing between $180^{\circ}$ domain walls decreases in order to reduce the magnetostatic energy. The effect of laser irradiation on iron loss and magnetostriction reduction for Fe-3%Si grain-oriented steel were investigated. Since the local tensile stresses were induced at the surface of Fe-3%Si steel by the laser irradiation, the minimum iron loss caused by reducing eddy current loss was obtained in spiete of the decrease of permeability by hindering eddy current loss was obtained in spite of the decrease of permeability by hindering the domain wall movement around the induced stress field. Furthermore, the laser treated 3%Si steel has lower magnetostriction as compared to non laser-treated steel and is less sensitive to applying pre-stresses due to the volume reduction of $90^{\circ}$ domain in materials.

• Laser Solutions
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• v.18 no.1
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• pp.12-17
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• 2015

This work performed numerical analysis of electromagnetic field and thermal phenomena occurring in femtosecond laser irradiation of silver nanowires. The local electric field enhancement was computed to calculate the optical energy dissipation as a Joule heating source and the thermal transport was analysed based on the two-temperature model (TTM). Electron temperature increased up to 1000K after 50fs and its spatial distribution became homogeneous after 80fs at the fluence of 100mJ/cm2. The result of this work is expected to contribute to revealing the photothermal effects on silver nanowires induced by femtosecond laser irradiation. Although the highest increase of lattice temperature was substantially below the melting point of silver, the experimental results showed resolidification and fragmentation of the silver nanowire into nanoparticles, which cannot be explained by the photothermal mechanism. Further studies are thus needed to clarify the physical mechanisms.

• Journal of Oral Medicine and Pain
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• v.30 no.4
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• pp.465-473
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• 2005

The purpose of this study was to evaluate the desensitizing effects of a Nd:YAG laser (Sunlase, SUNRISE Technologies, Inc., USA) irradiation on cervically exposed hypersensitive dentine. 45 patients was irradiated with pulsed Nd:YAG laser (1.5 W, 20 Hz, 75 mJ/pulse, 4 minutes) as the experimental group, 27 patients was mock irradiated as the control group. The degree of sensitivity to the thermal and tactile stimuli were determined qualitatively with an evaporative stimulus defined as two times air blast at a distance of 3 mm from each site to be tested and with a mechanical stimulus as a slightly scratching the cervical site with a dental explorer. A qualitative registration of the degree of discomfort was determined according to a numerical pain scale(NPS) in an 11-point scale in which 0= "no pain" and 10="most excruciating pain imaginable". Recordings were assessed before treatment, immediately after, 1 and 2 weeks after treatment. Pain tolerance threshold and pulp vitality were evaluated with electric pulp tester before and immediately after treatment. 1. Desensitizing of hypersensitive dentine with Nd:YAG laser irradiation was more effective than that with mock irradiation. 2. The placebo effect of mock irradiation was recognized for severe sensitive teeth($NPS\;{\geqq}\;6$), but not for moderate sensitive teeth(NPS < 6). 3. Laser irradiation did not affect the pain tolerance threshold and pulp vitality of the hypersensitive teeth. 4. Desensitizing effect of laser irradiation for the hypersensitive teeth had been continuing at least 2 weeks. It was concluded that desensitizing of hypersensitive dentine with a Nd:YAG laser is effective and the maintenance of the positive result was more prolonged than the placebo effect.

• Transactions on Electrical and Electronic Materials
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• v.11 no.5
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• pp.226-229
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• 2010

Many methods exist that promote wound healing, including light therapy, which consists of light beams that assist the human body in treating and sterilizing wounds, as well as regenerating cells. Irradiation with specific wavelengths of either laser or LED light has been shown to induce beneficial proliferation of fibroblasts that, depending on the size of the wound, can be effective in promoting wound healing. The experiments in this study utilized 8 week old 250~300 g Male Sprague Dawley Rats (ILAR Code: NTacSam:SD) and included a non-irradiation group and a 525 nm green LED irradiation group (n of each group = 7). In experiments animals were allowed to rest for 24 hours after wounds had been excised, which was followed by non- irradiation or 525 nm green LED irradiation therapy one hour per day for 9 days. Immunohistochemical staining was conducted for cytokeratin in order to precisely measure the defect size. In addition, Masson's trichrome staining was utilized in order to compare levels of collagen between the 525 nm green LED irradiation group and the non-irradiation group. Animals exposed to 525 nm green LED irradiation (p<0.05) healed at a faster rate and had increased collagenosis compared with the non-irradiated control group. Thus, treatment with 525 nm green LED irradiation had a beneficial effect on wound healing and should be considered as a possible alternative to low power laser treatment.

• Transactions on Electrical and Electronic Materials
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• v.8 no.6
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• pp.289-292
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• 2007

Polymethly methacrylate(PMMA) and polydimethlysiloxane(PDMS) surfaces were treated to improve adhesiveness by irradiation of a Nd:YAG pulse laser beam($\lambda=266nm$). A pulse laser beam was directed on a polymer surface in air, and the number of pulses was controlled by mobile velocity of a motorized stage. The laser treated surfaces were investigated using an optical microscope and a contact angle measuring instrument. It was thereby revealed that the contact angles were decreased in the laser treated surface. This in turn led to an increase of oxygen content and improved adhesiveness on the modified surface. With improved surface adhesion, a fluid channel could be formed on the laser treated surface region.

• Korean Journal of Acupuncture
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• v.27 no.1
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• pp.49-62
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• 2010

Objective: This study was performed to investigate the effect of manual acupuncture, invasive laser acupuncture and laser skin irradiation at LU8, LR4, HT8 and LR2(Liver Seunggyeok) on D-galN-induced liver injury in rats. Method: Liver injury was induced with D-galN. The experimental rats were divided four groups(Control group, EXP-1, EXP-2, EXP-3). In the Control group, liver injury-induced and not treated. EXP-1 group was liver injury-induced and carried out manual acupuncture with Young-Su(against the meridian course and following the course of the meridian) & Won-Bang(by twisting and rotating the needle) acupuncture method at Liver Seunggyeok. EXP-2 group was liver injury-induced and carried out invasive laser acupuncture at Liver Seunggyeok. EXP-3 group was liver injury-induced and carried out laser skin irradiation at Liver Seunggyeok. Result: In the change of body weight(in 1 week), EXP-1, EXP-2 and EXP-3 groups were significantly increased as compared with control group. In the change AST & ALT, EXP-1 and EXP-2 groups were significantly decreased as compared with control group. In the change of SOD, EXP-1, EXP-2 and EXP-3 groups were significantly increased as compared with control group. In the change of WBC, EXP-2 group was significantly increased as compared with control group. Conclusion: Manual acupuncture, invasive laser acupuncture and laser skin irradiation at Liver Seunggyeok had hepatotherapeutic effect on the treatment of hepatocytotoxity. Invasive laser acupuncture was as effective as manual acupuncture on the treatment of hepatocytotocity.

• Journal of Periodontal and Implant Science
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• v.44 no.5
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• pp.227-234
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• 2014

Purpose: Dentin hypersensitivity is a potential threat to oral health. Laser irradiation may provide reliable and reproducible treatment but remains controversial. The present study aimed to evaluate the effects of $CO_2$ or erbium-doped yttrium aluminium garnet (Er:YAG) laser therapy, and to assess mineral content. Methods: Eighteen human single-rooted teeth affected with advanced periodontitis were obtained. Buccal and lingual surfaces were planed to form 36 specimens. Ethylenediaminetetraacetic acid gel (24%) was applied to remove the smear layer and simulate hypersensitive teeth. The experimental groups were: group 1, control (no irradiation); group 2, $CO_2$ laser (repetitive pulsed mode, 2 W, $2.7J/cm^2$); and group 3, Er:YAG laser (slight contact mode, 40 mJ/pulse and 10 Hz). To evaluate dentinal tubule occlusion, six specimens per group (2-mm thickness) were prepared and observed using scanning electron microscopy (SEM) for calculation of the occlusion percentage. To evaluate the mineral content, six specimens per group (0.6-mm thickness) were used, and then the levels of Ca, K, Mg, Na, and P were measured by inductively coupled plasma-atomic emission spectrometry. In addition, the surface temperature of the specimens during laser irradiation was analyzed by a thermograph. Results: The SEM photomicrographs indicated melted areas around exposed dentinal tubules and a significantly greater percentage of tubular occlusion in the $CO_2$ and Er:YAG laser groups than the control, and in the Er:YAG group than the $CO_2$ laser group. In addition, no significant differences were noted among the experimental groups for the mineral elements analyzed. The $CO_2$ laser group showed an evident thermal effect compared to the Er:YAG group. Conclusions: $CO_2$ and Er:YAG laser are effective in treating dentin hypersensitivity and reducing its symptoms. However, the Er:YAG laser has a more significant effect; thus, it may constitute a useful conditioning item. Furthermore, neither $CO_2$ nor Er:YAG lasers affected the compositional structure of the mineral content.