• Laser Solutions
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• v.6 no.3
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• pp.19-28
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• 2003

The manufacturing process for the microfluidic device can include sequential steps such as master fabrication, electroforming, and injection molding. The laser ablation, using masks, has been applied to the fabrication of channels in microfluidic devices. In this research, an excimer laser was used to engrave microscopic channels on the surface of PET (polyethylene terephthalate), which shows a high absorption ratio for an excimer laser beam with a wavelength of 248 m. When 50-${\mu}{\textrm}{m}$-wide rectangular microscopic channels are ablated with a 500 ${\times}$ 500 ${\mu}{\textrm}{m}$ square mask at a magnification ratio of 1/10, ditch-shaped defects were found in both corners. The measurement of laser beam intensity showed that a coherent image in the PET target caused such defects. Analysis based on the Fourier diffraction theory enabled the prediction of the coherent shape at the image surface as well as the diffraction beam shape between the mask and the image surface. It also showed that the diameter of the aperture had a dominant effect. The application of aperture with a diameter of less than 3 mm helped to eliminate such defects in the ablated rectangular microscopic channels on PET without such ditch-shaped defects.

• Restorative Dentistry and Endodontics
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• v.25 no.2
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• pp.225-234
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• 2000

The purpose of this study was to investigate the distribution and fluorescene intensity of vasoactive intestinal polypeptide(VIP) immunoreactive cells in rat trigeminal ganglion after inferior alveolar nerve axotomy. The animals were divided into normal and two experimental groups. The experimental animals were sacrificed at 14th and 28th day after inferior alveolar nerve axotomy. The trigeminal ganglion was removed and immersed in the 4% paraformaldehyde-0.2% picric acid in 0.1M phosphate buffer. Serial frozon sections about $16{\mu}m$ in thickness were cut with a cryostat. The immunofluorescence staining was performed. The rabbit anti-VIP(1 : 8,000) was used as primary antibody and fluorescene isothiocynate(FITC)-conjugated anti-rabbit IgG(1 : 80) as secondary antibody. The slides were observed under confocal laser scanning microscope. Three-dimensional images were constructed from 9 serial images(each $1{\mu}m$ in thickness) made by automatic optical sectioning. Unprocessed optical sections were obtained and stored on a optical disk. Color picture were printed by a video copy processor. The results were as follows; 1. The appearance of VIP immunoreactive cells in the mandibular part of trigeminal ganglion was 8.79${\pm}$1.99% in normal group and 39.16${\pm}$5.62% in 14 days, 16.25${\pm}$2.39% in 28 days after inferior alveolar nerve axotomy groups. 2. The relative fluorescence intensity of VIP immunoreactive cell bodies in the mandibular part of trigeminal ganglion was 134.40${\pm}$10.39 in normal group and 192.88${\pm}$14.06 in 14 days, 143.10${\pm}$5.02 in 28 days after nerve axotomy groups. Therefore, the relative fluorescence intensity of 14 days after nerve axotomy group was 43.3% higher than intensity of normal group. 3. In optical single section analysis of VIP immunoreactive cell bodies, white cell bodies(moderate fluorescence intensity) were the most abundant in normal and 28 days after nerve axotomy groups. Whereas, in 14 days after nerve axotomy group, red cell bodies(high fluorescence intensity) were the most abundant. 4. In optical serial section analysis of VIP immunoreactive cell bodies, red cell bodies(high fluorescence intensity) were observed in a part of the 9 sections of normal and 24 days after nerve axotomy groups. Whereas, red cell bodies were observed in all of the 9 sections of 14 days after nerve axotomy group. 5. The results indicates that number and fluorescence intensity of VIP immunoreactive cells were increased in the mandibular part of trigeminal ganglion following inferior alveolar nerve axotomy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.3
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• pp.240-244
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• 2007

We investigated the diffraction grating efficiency by the Diode Pumped Solid State(DPSS 532 nm) laser beam wavelength to improve the diffraction efficiency on $As_{40}Ge_{10}Se_{15}S_{35},\;Ag/As_{40}Ge_{10}Se_{15}S_{35}$ and $As_{40}Ge_{10}Se_{15}S_{35}/Ag/As_{40}Ge_{10}Se_{15}S_{35}$ thin film. Diffraction efficiency was obtained from DPSS laser, used (P:P)polarized laser beam on each thin films. As a result, for the laser beam intensity in $0.24mW/cm^2$, single $As_{40}Ge_{10}Se_{15}S_{35}$ thin film shows the highest value of 0.161% diffraction efficiency at 300 s and for laser beam intensity in $2.4mW/cm^2$, it was recorded with the fastest speed of 50 s(0.013%), which the diffraction grating forming speed is faster than that of $0.24mW/cm^2$ beam. $Ag/As_{40}Ge_{10}Se_{15}S_{35}$ double layer and $As_{40}Ge_{10}Se_{15}S_{35}/Ag/As_{40}Ge_{10}Se_{15}S_{35}$ multi-layered thin film also show the faster grating forming speed at $2.4mW/cm^2$ and higher value of diffraction efficiency at $0.24mW/cm^2$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.1
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• pp.161-166
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• 2016

We studied the effect of $Co^{60}$ gamma-radiation on the FBGs by a variation of grating the fabrication parameters. The FBGs were fabricated in a different UV KrF laser intensity using the same boron co-doped photo-sensitive fiber and exposed to gamma-radiation up to a dose of 33.8 kGy. According to the experimental data and analysis results, We confirmed that the laser intensity for grating inscription has a highly effect on the radiation sensitivity of the FBGs and the radiation-induced Bragg wavelength shift by the change of laser process condition showed a difference more than about 30 %.

• Journal of the Korean Applied Science and Technology
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• v.30 no.2
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• pp.251-257
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• 2013

The influences of Methotrexate as fluorophor, scatterer, absorber in turbid material by light scattering were interpreted for the scattered fluorescence intensity and wavelength, it has been studied the molecular properties by laser induced fluorescence spectroscopy. It has been found that the effects of optical properties in scattering media by the optical parameters((${\mu}_s$, ${\mu}_a$, ${\mu}_t$). The value of scattering coefficient ${\mu}_s$ is large by means of the increasing particles of L-${\alpha}$-Phosphatidylcholine, it has been found that the slope decays exponentially as a function of depth from laser source to detector. It may also aid in designing the best model for oil chemistry, laser medicine and application of medical engineering.

• Korean Journal of Optics and Photonics
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• v.25 no.2
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• pp.61-66
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• 2014

We report the characterization of a wavelength-swept laser (WSL) using a polygon-based wavelength scanning filter and two semiconductor optical amplifiers (SOAs). The output intensity and scanning bandwidth of the WSL depend on the position of the two SOAs in the laser cavity and the coupling ratio of the output fiber coupler. The outputs of the WSL are characterized for coupling ratios of 10%, 30%, 50%, 70%, and 90% for the output fiber coupler. In the setup in which the output fiber coupler is located between the two SOAs, high output power and wide scanning bandwidth can be achieved with an optimized configuration. Using the optimized configuration of the WSL, the intensity increases with the coupling ratio. These results can be used to construct an optimized WSL using the polygon-based wavelength scanning filter.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.29-29
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• 2009

On this research, laser welding technology for manufacturing automobile body is studied. Laser welding technology is one of the important technologies used in the manufacturing of lighter, safer automotive bodies at a high level of productivity; the leading automotive manufacturers have replaced spot welding with laser welding in the process of car body assembly. Korean auto manufacturers are developing and applying the laser welding technology using a high output power Nd:YAG laser and a 6-axes industrial robot. On the other hand, the robot-based remote laser welding system was equipped with a long focal laser scanner system in robotic end effect. Laser system, robot system, and scanner system are used for realizing the high speed laser welding system. The remote laser welding system and industrial robotic system are used to consist of robot-based remote laser welding system. The robot-based remote laser welding system is flexible and able to improve laser welding speed compared with traditional welding as spot welding and laser welding. The robot-based remote laser systems used in this study were Trumpf's 4kW Nd:YAG laser (HL4006D) and IPG's 1.6kW Fiber laser (YLR-1600), while the robot systems were of ABB's IRB6400R (payload:120kg) and Hyundai Heavy Industry's HX130-02 (payload:130kg). In addition, a study of quality evaluation and monitoring technology for the remote laser welding was conducted. The welding joints of steel plate and steel plate coated with zinc were butt and lapped joints. The quality testing of the laser welding was conducted by observing the shape of the beads on the plate and the cross-section of the welded parts, analyzing the results of mechanical tension test, and monitoring the plasma intensity and temperature by using UV and IR detectors. Over the past years, Trumf's 4kW Nd:YAG laser and ABB's IRB6400R robot system was used. Nowadays, the new laser source, robot and laser scanner system are used to increase the processing speed and to improve the efficiency of processes. This paper proposes the robot-based remote laser welding system as a means of resolving the limited welding speed and accuracy of conventional laser welding systems.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.3
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• pp.185-192
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• 2021

Purpose : Our study aimed to compare the effectiveness of low-level laser therapy (LLLT) and light-emitting diode therapy (LEDT) for chronic pain intensity reduction and body temperature increase in older adults with chronic pain. Methods : Overall, 144 of 332 participants' records were used in this retrospective chart review. The study was conducted at a private health center in Busan city and the integrative medical center of a tertiary care hospital in Daegu city, South Korea. Patients experiencing chronic pain for over 6 months were assigned to either the LLLT or LEDT group. Both groups underwent 16 sessions of phototherapy held twice a week for 8 weeks, with each session lasting 60 minutes. The primary outcomes for both groups were the mean visual analogue scale (VAS) scores and body temperatures in both groups. The secondary outcome was the correlation between changes in body temperature and pain intensity. Measurements were recorded at the baseline and at each follow-up session. Results : A decrease in pain intensity and an increase in body temperature (p<.001) were observed in both groups. There was a significant difference in the VAS scores and temperature changes between the groups (p<.001). Odditionally, there were significant differences in the patterns of change in the VAS score and body temperature between the groups as the sessions progressed (p<.01), and a strong inverse correlation between body temperature and pain intensity changes were observed (p<.01). Conclusion : The use of photobiomodulation therapy at a specific wavelength may improve pain severity and simultaneously increase the body temperature among elderly people with chronic pain.

• Journal of Magnetics
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• v.11 no.2
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• pp.66-69
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• 2006

Local magnetization reversal in the exchange-biased NiFe/FeMn and $[Pd/Co]_5/FeMn$ multilayers with in-plane and out-of-plane magnetic anisotropy was achieved by using laser annealing. The local annealed NiFe/FeMn film under the opposite magnetic field shows a magnetoresistance (MR) curve having two symmetric peaks at the positive and negative exchange biasing field (${\pm}H_{ex}$). The intensity of the nucleated MR peak rises as the exposed area extends during the laser annealing process, and the peak disappears under the reverse magnetic field. In the case of [Pd/Co]/FeMn films, the local magnetization reversal increased gradually as the laser power increases. The locally reversed magnetization was restored under the opposite magnetic field.

• Laser Solutions
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• v.17 no.2
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• pp.19-25
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• 2014

Optical embedded diffraction gratings with the bulk modification in BK-7 glass plates excited by tightly focused high-intensity femtosecond (130fs) Ti: sapphire laser (peak wavelength = 790nm) were demonstrated. The structural modifications with diameters ranging from 400nm to $4{\mu}m$ were photo-induced after plasma formation occurred upon irradiation with peak intensities of more than $1{\times}1013W/cm^2$. The graded refractive index profile was fabricated to be a symmetric around from the center of the point at which low-density plasma occurred. The maximum refractive index change was estimated to be $1.5{\times}10^{-2}$. The two optical embedded gratings in BK-7 glass plate were demonstrated with refractive index modification induced by the scanning of low-density plasma formation.