• Proceedings of the Korean Society of Laser Processing Conference
• /
• 1998.05a
• /
• pp.40-42
• /
• 1998

• Proceedings of the KWS Conference
• /
• 2006.10a
• /
• pp.207-209
• /
• 2006

This study is about an effect on a characteristics of the laser heat treatment as a optic systems which have a transverse beam mode each other. An experiment are carried out using a circular gaussian beam optics and rectangular beam optics. Generally, the optic system which has a uniform power intensity is mainly used in the laser heat treatment process. In this study, we would like to carried out experiments simultaneously using two optic systems and research the differences from a characteristics of the laser heat treatment.

• Transactions of Materials Processing
• /
• v.24 no.5
• /
• pp.354-360
• /
• 2015

AHSS (Advanced High Strength Steels) has been increasingly employed by global automotive OEMs in order to satisfy strengthened regulations and reduce weight for fuel efficiency. Hot stamping using boron steels in AHSS increases not only formability but also strength. The typical hot-stamped automotive part is the center pillar that is critical for vehicle side impact. However, the hot-stamped part can be risky for the passenger safety caused by brittle fracture under a vehicle collision. The high power diode laser is suitable for the heat treatment giving AHSS increased elongation that prevents brittle fracture in car crash. Therefore, local softening by laser heat treatment for energy absorption area on the hot-stamped part improves crash-worthiness.

• Journal of the Korean Society for Heat Treatment
• /
• v.9 no.3
• /
• pp.177-186
• /
• 1996

Surface alloying of Ti alloy by $CO_2$ laser is able to produce few hundred micrometers thick TiN or TiC surface-alloyed layer with high hardness on the substrate by injecting reaction gas($N_2$ or $CH_4$). Laser surface alloying by means of process control is in many applications essential in order to obtain predictable hardening layer. This research has been investigated the effect of such parameters on TiN and TiC gas alloying of Ti-6Al-4V alloy by $CO_2$ laser. The maximum surface hardness of TiN layer was obtained 1750Hv on the conditions of 0.8kW laser power, 0.8m/min scanning speed and 100% $N_2$ atmosphere. However, the maximum hardness of TiC formation layer after laser treatment was about 630Hv. As scanning speed was increased, the hardness and depth of these layers were decreased at constant laser power.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
• /
• v.28 no.2
• /
• pp.131-134
• /
• 2017

Sulcus vocalis remains a surgical challenge despite many recent advances in laryngomicrosurgeries. We previously reported that 585-nm Pulsed dye laser (PDL) exerts favorable outcome in treatment of sulcus vocalis due to its therapeutic effects of collagen rearrangement and improved wound remodeling. In spite of the usefulness of PDL glottoplasty for treating sulcus vocalis, the device is no more available in the country. It prompted us to focus another angiolytic laser ; 532-nm KTP laser which has similar mechanisms of action and has been used for treatment of other laryngeal lesions elsewhere. Herein, we present a case of sulcus vocalis successfully treated with KTP laser. A patient underwent laryngomicrosurgery with angiolytic KTP laser (KTP glottoplasty) by the same surgical procedure with PDL glottoplasty. After the surgery, the patient presented improved voice outcome in time without complications.

• Korean Journal of Bronchoesophagology
• /
• v.6 no.2
• /
• pp.172-176
• /
• 2000

Background and Objectives： The treatment of laryngeal carcinoma is not settled to date and surgeons have used lasers for a variety of benign and malignant lesions in the larynx with good success. The aim of this study is to evaluate the potential role of laser surgery for laryngeal carcinoma. Materials and Methods : Medical records from patients who had undergone laser surgery for laryngeal carcinoma at Seoul National University Hospital between January 1988 3nd December 1998 were reviewed retrospectively. Results : A total of 47 patients were seen during that period and their mean follow-up length was 29 months. Their local control rate was 91％ (94% for glottic T1, 60% for glottic T2, 50% for supraglottic T1 and 100％ for supraglottic T2). The cure rate after laser surgery with or without postoperative radiotherapy was 87％ and 6 of 47 patients showed local or regional recurrences. For those 6 patients, neck dissection, partial or total laryngectomy with or without postoperative RT were conducted and they were all followed up without evidence of disease. All 47 patients who had undergone laser surgery for laryngeal squamous cell carcinoma were followed up with NED and their larynx preservation rate was 96%. Conclusion： This study demonstrates the oncologic validity of laser surgery to the treatment of unadvanced laryngeal carcinoma. However, strict case selection is needed to avoid locoregional recurrences and consequent salvage operations.

• Journal of the Korean Society for Heat Treatment
• /
• v.24 no.4
• /
• pp.203-208
• /
• 2011

Recently, from general machine parts and automobile parts using carbon steel to a mold, there has been efforts for improving durability and attrition resistance of these parts. Especially, heat treatment with laser which works fast and automatically can be used for the mass production with high quality. Moreover, local heat treatment can be used to handle with complex and precise parts. Accordingly, we analyzed hardening characteristics of carbon steel using the finite element method and compare the experimental results to have more reliability. We also proved the cause of thermal deformation with temperature and stress distribution by heat treatment. After these analysis and experimental, we found that each maximum hardness of the two tests was 728 Hv and 700 Hv, on condition of $1050^{\circ}C$ heating temperature, and 2 mm/sec laser speed. We also found that difference of surface stress-distribution was occurred, and this makes deformation mode up after heat treatment.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.19 no.2
• /
• pp.181-184
• /
• 2006

Nd:YAG($\lambda$=266 nm, pulse) laser beam was irradiated on the PDMS surface to improve its chemical reaction, wettability, adhesive property. The various surface modification methods of PDMS were already studied using oxygen plasma, ozone and corona discharge. The surface modification using laser has the advantage of the simple experiment that only directly irradiated laser beam on the PDMS surface in the air. After the laser treatment, the PDMS surface was investigated using a contact angle measuring instrument. The contact angle was decreased with a increase of the surface oxygen content. In conclusion, the wettability of PDMS surface was improved by the laser treatment without changing of its bulk characteristics.

• Medical Lasers
• /
• v.10 no.4
• /
• pp.201-206
• /
• 2021

The recent development of new surgical techniques using lasers has increased the opportunities for open surgery involving minimal manipulation and faster and more accurate removal of lesions. The increasing use of laser technology requires nurses to play an extensive role. As assistants, nurses play an important role in maintaining the efficacy and safety of the laser device. In addition, they are also responsible for providing pre-and post-operative care to patients. Therefore, nurses should be aware of how to proceed with operative laser treatment for all surgical procedures and the steps for maintaining safety prior to, during, and after laser treatment. This review provides in-depth knowledge for nurses undertaking continuing education on lasers and patient care in the field of gynecology.

• The Journal of Advanced Prosthodontics
• /
• v.8 no.3
• /
• pp.235-240
• /
• 2016

PURPOSE. In this study, the aim of this study was to evaluate the effect of implant surface treatment on cell differentiation of osteoblast cells. For this purpose, three surfaces were compared: (1) a modified SLA (MSLA: sand-blasted with large grit, acid-etched, and immersed in 0.9% NaCl), (2) a laser treatment (LT: laser treatment) titanium surface and (3) a laser and acid-treated (LAT: laser treatment, acid-etched) titanium surface. MATERIALS AND METHODS. The MSLA surfaces were considered as the control group, and LT and LAT surfaces as test groups. Alkaline phosphatase expression (ALP) was used to quantify osteoblastic differentiation of MC3T3-E1 cell. Surface roughness was evaluated by a contact profilometer (URFPAK-SV; Mitutoyo, Kawasaki, Japan) and characterized by two parameters: mean roughness (Ra) and maximum peak-to-valley height (Rt). RESULTS. Scanning electron microscope revealed that MSLA (control group) surface was not as rough as LT, LAT surface (test groups). Alkaline phosphatase expression, the measure of osteoblastic differentiation, and total ALP expression by surface-adherent cells were found to be highest at 21 days for all three surfaces tested (P<.05). Furthermore, ALP expression levels of MSLA and LAT surfaces were significantly higher than expression levels of LT surface-adherent cells at 7, 14, and 21 days, respectively (P<.05). However, ALP expression levels between MSLA and LAT surface were equal at 7, 14, and 21 days (P>.05). CONCLUSION. This study suggested that MSLA and LAT surfaces exhibited more favorable environment for osteoblast differentiation when compared with LT surface, the results that are important for implant surface modification studies.