• Korean Journal of Materials Research
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• v.19 no.9
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• pp.457-461
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• 2009

Recently, metal molding has become essential not only for automobile parts, but also mass production, and has greatly influenced production costs as well as the quality of products. Its surface has been treated by carburizing, nitriding and induction hardening, but these existing treatments cause considerable deformation and increase the expense of postprocessing after treatment; furthermore, these treatments cannot be easily applied to parts that requiring the hardening of only a certain section. This is because the treatment cannot heat the material homogeneously, nor can it heat all of it. Laser surface treatment was developed to overcome these disadvantages, and, when the laser beam is irradiated on the surface and laser speed is appropriate, the laser focal position is rapidly heated and the thermal energy of surface penetrates the material after irradiation, finally imbuing it with a new mechanical characteristic by the process of self-quenching. This research estimates the material characteristic after efficient and functional surface treatment using HPDL, which is more efficient than the existing CW Nd:YAG laser heat source. To estimate this, microstructural changes and hardness characteristics of three parts (the surface treatment part, heat affect zone, and parental material) are observed with the change of laser beam speed and surface temperature. Moreover, the depth of the hardened area is observed with the change of the laser beam speed and temperature.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.138-139
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• 2007

The microstructure and micro-hardness of high velocity oxygen fuel-sprayed (HVOF) WC-CoCr coatings are comparatively studied for both before and after laser heat-treatment (LT) of the coatings. The results indicate that compared to HVOF WC-CoCro coating, the laser treatment has eliminated the pores almost entirely providing a more homogeneous and densified microstructure. And the compact interface of the coating with substrate is achieved by laser treatment. The thickness of the coating has decreased from 300 ${\mu}m$ to 225 ${\mu}m$ As a result, the average porosity is five times higher in HVOF coating than in the coating by laser treatment. The laser treatment has produced a considerable increment in the hardness of the coating near surface whose average value increases from Hv0.2=1262.4 in the HVOF-sprayed coating to Hv0.2=1818.7 in the coatings treated with laser.

• Laser Solutions
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• v.18 no.2
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• pp.1-4
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• 2015

This study is related to the surface hardening treatment to spheroidal graphite cast iron for die by using high power diode laser. Laser device used in this experiment is capable of real-time laser power control. This is because the infrared temperature sensor (two color pyrometer) attached to the optical system measures the surface temperature of specimen and adjusts the laser power in real time. The surface treatment was carried out with the change of heat treatment temperature at the beam travel speed 3 mm/sec. Hardened width and depth was measured and hardened zone was analyzed by micro vickers hardness test in order to research the optimum condition of heat treatment. The changes in microstructure of the hardened zone also was examined. As a result of hardness measurement and observations on microstructure of hardened zone, hardness increased over three times as compared with base metal because the martensite was formed on the matrix structure.

• The Journal of Korean Physical Therapy
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• v.18 no.6
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• pp.13-21
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• 2006

Purpose: To provide the basic method for physical therapy to contribute to early stage treatment of a burned patients. We investigated whether or not carbon arc lamp treatment and low level laser one among various laser treatments have the effect of reducing Cytokine, and to elucidate the effect of carbon arc lamp treatment and laser one. Methods: The 6-week old BALB/c types of 92 mice were used for the experimental test, and they were burned with $100^{\circ}C$ water, they were divided into 4 groups in accordance with the method of treatment respectively. And the blood and the tissue from the subject of each group were extracted and analyzed each time after they were cured for 3, 6, 9 days. For the analysis of the results, SPSS statistical program was used in this study. Results: The quantity of $TNF-{\alpha}$ and $IL-1{\beta}$ within the blood of a burned mouse increased more than that of a normal mouse(p<0.01). In only a burned mouse, carbon arc lamp treatment gave the effect on the decrease of $TNF-{\alpha}$ thickness the 6th day to the 9th day(p<0.01). $IL-1{\beta}$ quantity was more decreased than that of control group around the 6th day. In comparison with only a control group, low level laser treatment has more significant effect in decreasing the quantity of $TNF-{\alpha}$ a and $IL-1{\beta}$ than the two different methods(p<0.01). In case that the two treatment methods, carbon arc lamp treatment and low level laser, were executed together, there was the effect of decreasing $TNF-{\alpha}$ until the 6th day(p<0.01). Conclusion: Both low level laser treatment and carbon arc lamp one would be able to have an effect on the inflammation inhibition of burned patients and tissues reproduction. However, it must be also considered for the two treatments to be done at the same time.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.1048-1054
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• 2011

Laser surface hardening process is the method of hardening surface by inducing rapid self quenching of laser injected area through transfer of surface heat to inside after rapid heating of laser injected area only by high density energy heat source. This surface treatment method does not involve virtually any thermal deformation by heat treatment nor accompanies any other process after surface hardening treatment. In addition, allowing local machining, this method is a surface treatment method suitable for die with complicated shape. In this study, die material cast iron was surface-treated by using high power diode laser with beam profile suitable for heat treatment. Since the shapes of die differ by press die process, specimens were heat-treated separately on plane and corner depending on the applied parts. At this time, corner heat treatment was done with optic head inclined at $10^{\circ}$. As a result, corner heat treatment easily involves concentration of heat input due to limitation of heat transfer route by the shapes compared with plane part, so the treatment accomplished hardening at faster conveying speed than plane heat treatment.

• Medical Lasers
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• v.10 no.3
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• pp.138-145
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• 2021

Low-level laser therapy or photobiomodulation (LLLT/PBM) therapy has been widely applied to enhance and accelerate the recovery of oral mucositis. This study investigates the documented effect of LLLT on oral mucositis caused by chemotherapy. This review appraises 6 animal studies and 12 clinical studies published in the Pubmed database during the past 10 years, related to the application of LLLT for the treatment of mucositis. Despite varied parameters and diverse conditions, the assessed articles indicate that application of LLLT on oral mucositis using near-infrared wavelengths is prophylactic, reduces pain, and enables a rapid recovery. Various combined treatments were also identified among the published papers, which further establishes the efficacy of LLLT as a viable treatment.

• Medical Lasers
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• v.9 no.1
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• pp.84-87
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• 2020

Post-acne erythema (PAE) is one of the major problems during or after treatment of acne vulgaris with any modality. A variety of therapeutic options have been described with various clinical outcomes and side effects. We report here on treating a patient with PAE using 595-nm picosecond-domain neodymium:yttrium-aluminum-garnet (Nd:YAG) laser. After four sessions of treatment, the patient displayed nearly complete improvement and no remarkable adverse effects. To the best of the authors' knowledge, this is the first case of the effective treatment of PAE using a 595-nm picosecond-domain Nd:YAG laser. We recommend that using a 595-nm picosecond-domain Nd:YAG laser can be both an effective and safe treatment option for treating PAE.

• Medical Lasers
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• v.10 no.1
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• pp.45-48
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• 2021

Background and Objectives Among the numerous available therapies, the usefulness of laser treatment has been proven in melasma, especially for refractory to topical agents or chemical peels. This study evaluated the effectiveness of 694-nm wavelength fractional toning ruby laser in melasma presenting on the malar area. Materials and Methods This was a retrospective study of 40 melasma patients treated with 694-nm wavelength ruby fractional toning laser for a total of 8 cycles at intervals of 2 to 3 weeks. Two independent investigators assessed the photographic findings and evaluated the severity of melasma by applying the Melasma Severity Scale (MSS). Subject satisfaction score was also surveyed at every visit. Results After the 4th treatment, subjects were continuously satisfied with their results. At the 8th visit and 1-month after the last treatment, MSS was determined to be significantly improved as compared to the first visit. One case of minor hypopigmentation was reported, but was resolved after one month. Conclusion Application of 694-nm wavelength fractional toning ruby laser for treating melasma on the malar area showed significant improvement in the MSS. Moreover, the treatment could be repeatedly applied, with low complication rate and significant patient satisfaction.

• Medical Lasers
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• v.8 no.2
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• pp.90-93
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• 2019

The treatment of keloid and hypertrophic scars (HTSs) remains one of the most difficult challenges, with a high recurrence rate regardless of the method of treatment. The latest trend in scar management is a combined approach using multiple modalities that are individualized to the patient and that would provide successful results for keloid and HTSs. There are previous reports that stromal vascular fraction (SVF) is effective for scar remodeling. Based on these reports, we introduced the concept of a combination treatment using SVF injection and fractional ablative CO₂ laser. In this report, we present a 21-year-old woman who was involved in a car accident. A defect on her foot was covered with a skin graft, but the scars became elevated, which turned out to be HTSs. She was treated with a fractional ablative CO₂ laser for five sessions. A month later, SVF injection and fractional ablative CO₂ laser were conducted simultaneously. The result of a year's follow-up showed a flattened scar with resolution of pigment deposition. In conclusion, the combination treatment for HTSs with SVF injection and ablative fractional CO₂ laser is one of the modalities to achieve an excellent outcome for treating HTS.

• Journal of Korean Dental Science
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• v.9 no.1
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• pp.19-27
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• 2016

Purpose: Laser treatment has become a popular method in implant dentistry, and lasers have been used for the decontamination of implant surfaces when treating peri-implantitis. This study was performed to evaluate the effects of an Erbium-doped:Yttrium-Aluminum-Garnet (Er:YAG) laser with different settings on machined (MA), sand-blasted and acid-etched (SA), and resorbable blast media (RBM) titanium surfaces using scanning electron microscopy and confocal microscopy. Materials and Methods: Four MA, four SA, and four RBM discs were either irradiated at 40 mJ/20 Hz, 90 mJ/20 Hz, or 40 mJ/25 Hz for 2 minutes. The specimens were evaluated with scanning electron microscopy and confocal microscopy. Result: The untreated MA surface demonstrated uniform roughness with circumferential machining marks, and depressions were observed after laser treatment. The untreated SA surface demonstrated a rough surface with sharp spikes and deep pits, and the laser produced noticeable changes on the SA titanium surfaces with melting and fusion. The untreated RBM surface demonstrated a rough surface with irregular indentation, and treatment with the laser produced changes on the RBM titanium surfaces. The Er:YAG laser produced significant changes on the roughness parameters, including arithmetic mean height of the surface (Sa) and maximum height of the surface (Sz), of the MA and SA surfaces. However, the Er:YAG laser did not produce notable changes on the roughness parameters, such as Sa and Sz, of the RBM surfaces. Conclusion: This study evaluated the effects of an Er:YAG laser on MA, SA, and RBM titanium discs using confocal microscopy and scanning electron microscopy. Treatment with the laser produced significant changes in the roughness of MA and SA surfaces, but the roughness parameters of the RBM discs were not significantly changed. Further research is needed to evaluate the efficiency of the Er:YAG laser in removing the contaminants, adhering bacteria, and the effects of treatment on cellular attachment, proliferation, and differentiation.