• Medical Lasers
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• 제10권1호
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• pp.52-54
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• 2021

There is growing interest in minimizing postoperative scarring after a thyroidectomy. Among the many treatment types, laser therapy, especially picosecond-domain laser therapy, is accepted as a standard method. In the present case, a patient with a pigmented, contracted scar was treated using the combination of a picosecond laser and ablative fractional (AF) CO₂ laser. After 15 sessions of 1,064-nm picosecond with micro lens array (MLA) and AF CO₂ laser application, the patient showed significant improvement in their pigmented lesions and scar contracture with no noticeable side effects for 16 months. These results suggest that a combination of picosecond laser with MLA and AF CO₂ laser can treat pigmented, contracted scars safely and effectively.

• Proceedings of the KACD Conference
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• 대한치과보존학회 2001년도 추계학술대회(제116회) 및 13회 Workshop 제3회 한ㆍ일 치과보존학회 공동학술대회 초록집
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• pp.556-556
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• 2001

The application of the laser to the tooth hard tissue started from the removal of carious dentin with the laser performed by Goldman in 1964. With the development of the laser technology, the laser treatment with less descomfort such as pain, vibration, and noise, etc. has been attempted. Since it is difficult to give a suitable form for inlay restoration to a cavity prepared with laser, it has to be restored with adhesive resinous materials. However, various evaluation of adhesive properties of the resinous materials to lased tooth surface on the various conditions such as adgerent, irradiation condition, procedure of bond test, and adhesive materials used, etc. have been reported.(omitted)

• Journal of Advanced Marine Engineering and Technology
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• 제35권5호
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• pp.600-607
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• 2011

Recently, high carbon steel has become essential not only for shipbuilding parts, but also mass production. 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, microstructural changes and hardness characteristics of two parts (the surface treatment part, and parental material) are observed with the change of laser beam speed and surface temperature.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• 제13권2호
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• pp.139-144
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• 2002

Background and objectives : The various voice-conserving treatments are used for Tla staged glottic cancer. Especially, Tla staged glottic cancer has been shown excellent treatment result after laser cordectomy or radiotherapy. To evaluate which treatment results better voice after treatment made it valuable to define the exact indication and recommending treatment modality on the Tla staged glottic cancer patients. Method : The medical records of 75 patients with glottic TlaN0 cancer diagnosed at Asan medical center, University of Ulsan college of medicine form May, 1989 to July,2001 were retrospectively reviewed on the point of voice quality and oncology including 5-year survival rate and local control rate. Results : Laser cordectomy and radiotherapy showed 100% and 94.0% 5-year survival rate, respectively. And laser cordectomy had 94.3% local control rate while radiotherapy got 87.6% local control rate. Voice analysis of pretreatment and posttreatment were used to compare each result. Fundamental frequency(F0), shimmer, jitter, noise to harmony ratio(NHR), maximum confortable phonation time(MPT) and vocal efficiency(VE) were used for parameters for voice analysis. Only in shimmer and MPT, we could find significant posttreatment difference between two therapies. In addition, we reviewed the total expenses for each therapy. Conclusion : On the basis of the oncologic result, both the laser cordectomy and radiotherapy had the similar results. Laser cordectomy showed the relatively acceptable voice as radiotherapy did. Laser cordectomy cost less than radiotherapy did. Laser cordectomy can be used for treatment about Tla staged glottic cancer.

• Archives of Plastic Surgery
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• 제42권1호
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• pp.52-58
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• 2015

Background The erbium:yttrium scandium gallium garnet (Er:YSGG) laser differs from other laser techniques by having a faster and higher cure rate. Since the Er:YSGG laser causes an appropriate proportion of ablation and coagulation, it has advantages over the conventional carbon dioxide ($CO_2$) laser and the erbium-doped yttrium aluminum garnet (Er:YAG) laser, including heating tendencies and explosive vaporization. This research was conducted to explore the effects and safety of the Er:YSGG laser. Methods Twenty patients participated in the pilot study of a resurfacing system using a 2,790-nm Er:YSGG laser. All patients received facial treatment by the 2,790-nm Er:YSGG laser system (Cutera) twice with a 4-week interval. Wrinkle reduction, reduction in pigment inhomogeneity, and improvement in tone and texture were measured. Results Study subjects included 15 women and five men. Re-epithelization occurred in all subjects 3 to 4 days after treatment, and wrinkle reduction, reduction in pigment inhomogeneity, and improvement in tone and texture within 6 months of treatment. Conclusions The 2,790-nm YSGG laser technique had fewer complications and was effective in the improvement of scars, pores, wrinkles, and skin tone and color with one or two treatments. We expect this method to be effective for people with acne scars, pore scars, deep wrinkles, and uneven skin texture and color.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• 제20권5호
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• pp.646-652
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• 2011

Recently, lots of automobile part manufacturers try to increase glass fiber content of their plastic parts to improve strength and impact-resistance. For this reason, injection mold requires high hardness and wear-resistant. Laser surface treatment is used to improve characteristics of wear and to enhance the fatigue resistance for injection mold. In this paper, high carbon steel (HP4MA) for injection mold material was heat-treated to harden surface by using high power diode laser (HPDL). To find the process parameters for laser surface treatment of HP4MA, many experiments are carried out as changing the parameters of surface temperature and travel speed of laser. From the results of the experiments, it has been shown that the maximum average hardness is approximately 711~739 Hv when the temperature and the travel of laser are $1,050^{\circ}C$ and 2 mm/sec.

• Medical Lasers
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• 제10권2호
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• pp.90-95
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• 2021

Background and Objectives Surgery for harvesting costal cartilage is often required for revision septorhinoplasty due to a lack of septal cartilage in patients with a severely contracted nose, and postoperative scarring on the anterolateral rib cage commonly requires additional treatment. This study aimed to evaluate the therapeutic efficacy and safety of combined polydeoxyribonucleotide (PDRN) and microlens array (MLA)-type nanosecond-domain neodymium (Nd):yttrium-aluminum-garnet (YAG) laser treatment for postoperative scars after costal cartilage harvest surgery. Materials and Methods Nine Korean patients with scars after costal cartilage harvest surgery treated with PDRN injections and MLA-type Nd:YAG laser treatments were retrospectively reviewed. Results Most of the scar lesions exhibited clinical improvement at 2 weeks after PDRN and MLA-type nanosecond-domain laser treatments, and the lesions further improved after adding more treatment sessions. The median Vancouver Scar Scale (VSS) score decreased from 6 (interquartile range [IQR]: 6-7) before combined intralesional PDRN injection and MLA-type, nanosecond-domain Nd:YAG laser treatments to 3 (IQR: 2-4) thereafter. Patient satisfaction after the combination treatments was rated as satisfactory. None of our patients reported major adverse events. Conclusion This case series study demonstrated that combined PDRN and MLA-type, nanosecond-domain Nd:YAG laser treatments are effective and safe for treating scars from costal cartilage harvest surgery.

• Medical Lasers
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• 제9권2호
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• pp.179-183
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• 2020

The picosecond laser has been widely used to remove tattoos, and improve wrinkles, acne scarring, and pigmented scars. This study was performed to investigate the efficacy and safety of a 1,064-nm fractional picosecond laser treatment for depressed traumatic scars. A total of twenty Korean patients with depressed scars were treated with a 1,064-nm fractional picosecond laser at a two-week interval with a spot size of 3 mm, fluence of 3.5 to 5.5 J/cm², and frequency of 2 Hz with a combination of microlens arrays. At 4 weeks after the final treatment, there was a statistically significant improvement in the modified Vancouver Scar Scale (mVSS) and the patient satisfaction score without any significant complication. A 1,064-nm fractional picosecond laser treatment is a safe and effective method to improve traumatic wound scars with depression.

• Journal of the Korean Physical Society
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• 제73권11호
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• pp.1619-1624
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• 2018

Laser ablation may provide a minimally invasive palliative treatment for pancreatic cancer. The aim of the current study was to assess the feasibility of a 532-nm laser equipped with a cylindrical light diffuser for the treatment of pancreatic cancer. Monolayers of BxPC-3 human pancreatic cancer cell were exposed to 532 nm laser light. Power levels of 5 - 7 W were used to uniformly target the entire cell colonies for 60 and 120 seconds. The cells were incubated for 24 hours after treatment and viabilities were determined by using a MTT assay. Laser ablation was performed by using the cylindrical light diffuser on six pancreatic tumor tissues obtained from pancreatic cancer xenograft mouse models, which were exposed to the 532 nm light at 5W or 7W for 10 to 30 seconds. In the in vitro study, the survival rates of the pancreatic cancer cells were reduced by 6.6% to 98.9% after the treatment, and the survival rates were reduced by increasing laser power and/or irradiation time. In the pancreatic tumor tissues, a homogenous circular ablation zone was observed in all tumors and the ablation distance induced by the laser irradiation showed to be constant from the diffuser to all directions (standard deviation, 0.3 - 1.3 mm). Ablation distance and area increased with increasing laser power and/or irradiation time. The 532 nm laser effectively killed pancreatic cancer cells, and the cylindrical light diffuser was found to be suitable for laser ablation as it provided uniform ablation in pancreatic cancer.

• Biomedical Science Letters
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• 제10권3호
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• pp.231-235
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• 2004

This study was investigated the effects of the lower power He-Ne IR laser treatment on the changes of blood biochemical components in the rat liver damaged by the carbon tetrachloride (CCl₄). The twenty one Sprague-Dawley adult male rats weights (260±18.6 g) were designed to the three groups: one control group and two experimental groups, the experimental groups were divided into the CCl₄-treated groups and the laser therapy group (CCl₄+ Laser). The experimental groups were injected twice with CCl₄(1.0 ml/kg body weight) intraperitoneal for two days. Each group was sacrificed after two weeks irradiated with the lower power He-Ne IR laser for ten minutes per every day. The activity of alanine aminotransferase (ALT), lactic dehydrogenase (LDH), alkaline phosphatase (ALP) and the concentration of serum glucose treated with He-Ne IR laser groups was significantly decreased to the conrtol (treated with carbon CCl₄) group. The activity of aspartate aminotransferase (AST) was decreased in the laser group but not significantly, the concentration of the serum cholesterol in the laser group was significantly increased comparing with the control and case control groups. In conclusion, the effect of the lower power He-Ne IR laser treatment is believed to be a possible protective effects for CCl₄ induced acute hepatotoxicity in rats.