• Physical Therapy Rehabilitation Science
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• v.3 no.1
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• pp.1-6
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• 2014

Objective: Low level laser treatment (LLLT) is widely used in physical therapy practice. It is combined with physical therapy or LLLT alone. The purpose of this study is to evaluate the effectiveness of LLLT on patients' perception of general wrist pain. Design: Longitudinal study. Methods: Forty-eight subjects with wrist pain who were in the age range of 18-70 years old were examined. The subjects were asked, via an interview and a visual analog scale, to grade their wrist pain. They were asked to rotate their wrists through full range of motion and the angle at which any pain occurred was assessed. Each subject was then exposed to one of the following: 1) treatment with an infrared laser with the power turned off (placebo), 2) treatment with an infrared therapeutic laser, 3) treatment with a red therapeutic laser, 4) treatment with an ultraviolet laser, 5) treatment with a blue laser, 6) treatment with a Mickey Mouse flashlight. The duration of the treatment was 3 sessions in 3 days. Results: The results of the experiments showed that while pain was reduced both immediately after and the next day after laser therapy (p<0.05), there was no significant difference between the laser groups and the placebo group. However, the Mickey Mouse flashlight treatment groups had a greater range of motion than the laser groups (p<0.05). Conclusions: While pain was reduced in all laser groups, it was probably a placebo effect. The Mickey Mouse flashlight group probably received benefit from the heat of the flashlight.

• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1361-1365
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• 2013

The smallest ketenimine and hydrogen cyanide N-methylide ($CH_2CNH$ and $CH_2NCH$) are provided from the argon/acetonitrile matrix samples exposed to radiation from laser ablation of transition-metals. New infrared bands are observed in addition to better determination of the vibrational characteristics for the previously reported bands, and the $^{13}C$ substituted isotopomers ($^{13}{CH_2}^{13}CNH$ and $^{13}CH_2N^{13}CH$) are also generated. Density functional frequency calculations and the D and $^{13}C$ isotopic shifts substantiate the vibrational assignments. $CH_2CNH$ is probably produced through single-step conversion of $CH_3CN$, whereas $CH_2NCH$ through two-step conversion via 2H-azirine. Inter-conversions between these two products evidently do not occur during photolysis and annealing.

• Current Optics and Photonics
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• v.3 no.6
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• pp.577-582
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• 2019

We report on a continuous-wave (cw) optical parametric oscillator (OPO) optimized for mid-infrared emission above 5.0 ㎛. The OPO is based on a magnesium-oxide-doped periodically poled LiNbO₃(MgO:PPLN) crystal with a fan-out grating design. A linear two-mirror cavity resonating both at the pump and signal wavelengths is stabilized to the pump laser by using the modified Pound-Drever-Hall (PDH) method. The idler wavelength is continuously tunable from 4.7 ㎛ up to 5.3 ㎛ by varying the poling period of the fan-out grating crystal. Pumped by a diode-pumped solid state (DPSS) laser with a power of 1.1 W at 1064 nm, the maximum idler output power is measured to be 5.3 mW at 4.8 ㎛. The output power above 5.0 ㎛ is reduced to the hundreds of ㎼ level due to increased absorption in the crystal, but is stable and strong enough to be measured with a conventional detector.

• Current Optics and Photonics
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• v.3 no.1
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• pp.33-39
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• 2019

We report development of a frequency-stabilized mid-infrared continuous-wave (cw) optical parametric oscillator (OPO) based on a fan-out grating MgO:PPLN crystal pumped at 1064 nm. The OPO resonator was designed as a pump-enhanced standing-wave cavity that resonates to the pump and signal beams. To realize stable operation of the OPO, we applied a modified Pound-Drever-Hall technique, which is a well-known method for powerful laser frequency stabilization. Tuning a poling period of the fan-out grating of the crystal allows wavelength-tunable OPO outputs from 1510 nm to 1852 nm and from 2500 nm to 3600 nm for signal and idler beams, respectively. At the idler wavelengths of 2500 nm, 3000 nm and 3500 nm, we achieved more than 50 mW of output powers at a pumping power of 1.1 W. The long-term stability of the OPO was confirmed by recording the power and wavelength variations of the idler for an hour.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.147.1-147.1
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• 2016

Hydrophobic thin films are variously applicable for encapsulation of organic devices and water repulsive glass, etc. In this work, the stability of hydrophobic characteristics of plasma polymerized tetrakis (trimethylsilyloxy) silane (ppTTMSS) thin films were investigated. The films were deposited with plasma enhanced chemical vapor deposition (PECVD) on the glass. The deposition plasma power and deposition pressure was 70 W and 600 mTorr, respectively. Thereafter, deposited films were treated by 248nm KrF excimer laser. Stability of hydrophobic properties of plasma polymerized tetrakis(trimethylsilyloxy)silane film surface was tested by excimer laser irradiation, which is thought to simulate severe outdoor conditions. Excimer laser irradiation cycles changed from 10 to 200 cycles. The chemical structure and hydrophobicity of ppTTMSS films were analyzed by using Fourier transform infrared (FTIR) spectroscopy and water contact angle (WCA) measurement, respectively. Absorption spectra peaks and WCA of excimer laser treated ppTTMSS films did not change notably. These results show that our ppTTMSS films possess stable hydrophobic properties.

• Journal of the korean academy of Pediatric Dentistry
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• v.48 no.1
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• pp.21-30
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• 2021

The purpose of this study is to investigate the antibacterial effects of indocyanine green (ICG) and near-infrared diode lasers on multispecies biofilms. Multispecies biofilms of Streptococcus mutans, Lactobacillus casei and Candida albicans were treated with different irradiation time using photosensitizer ICG and 808 nm near-infrared diode laser. Colony forming unit (CFU) was measured, and qualitative evaluation of biofilm was performed with confocal laser scanning microscopy (CLSM). Temperature measurement was conducted to evaluate photothermal effect. In the groups using ICG and diode laser, reduction in CFU was statistically significant, but the difference in antibacterial effect on L. casei and C. albicans with irradiation time was not significant, and similar results were confirmed with CLSM. Groups with ICG and diode laser showed higher temperature elevation than groups without ICG, and results of measured temperature were similar to the range of hyperthermia. In conclusion, ICG and near-infrared diode laser showed antibacterial effects on multispecies biofilms, but studies on protocol are necessary for clinical application.

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2093-2096
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• 2014

2H-azirine, a less known acetonitrile isomer, is observed in matrix IR spectra from the precursor exposed to radiation from laser ablation of transition-metals. Its vibrational characteristics confirm the previous results, and those for the deuterated and $^{13}C$ substituted isotopomers are also newly reported. The weak absorptions are traced to the low production yield due to its high energy and low extinction constants. IRC computations reveal smooth inter-conversion between 2H-azirine and $CH_2NCH$, providing a rationale for the observed variation of their relative contents during photolysis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.208-211
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• 2003

The dielectric carbon nitride thin films were deposited onto Si(100) using a pulsed laser ablation of pure graphite target combined with a high voltage discharge plasma in nitrogen gas atmosphere. We can be calculated dielectric constant, ${\varepsilon}_s$, with a capacitance Sobering bridge method. We reported to investigate the influence of the laser ablation of graphite target and DC high voltage source for the plasma. The properties of the deposited carbon nitride thin films were influenced by the high voltage source during the film growth. Deposition rate of carbon nitride films were found to increase drastically with the increase of high voltage source. Infrared absorption clearly shows the existence of C=N bonds and $C{\equiv}N$ bonds. The carbon nitride thin films were observed crystalline phase, as confirmed by x-ray diffraction data.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.7
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• pp.641-646
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• 2003

The dielectric carbon nitride thin films were deposited onto Si(100) substrate using a pulsed laser ablation of pure graphite target combined with a high voltage discharge plasma in the presence of a N$_2$ reactive gas. We calculated dielectric constant, $\varepsilon$$\_$s/, with a capacitance Schering bridge method. We investigated the influence of the laser ablation of graphite target and DC high voltage source for the plasma. The properties of the deposited carbon nitride thin films were influenced by the high voltage source during the film growth. Deposition rate of carbon nitride films were increased drastically with the increase of high voltage source. Infrared absorption clearly shows the existence of C=N bonds and C=N bonds. The carbon nitride thin films were observed crystalline phase confirmed by x-ray diffraction data.

• Bulletin of the Korean Chemical Society
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• v.12 no.6
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• pp.652-658
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• 1991

The effect of intermolecular collisions in the infrared multiphoton dissociation (IRMPD) of difluorochloromethane was investigated using He, Ar, and $N_2$ as buffer gases. The reaction probability for IRMPD of difluorochloromethane was measured as a function of laser fluence and the buffer gas pressure under unfocused beam geometry. It was observed that the reaction probability was initially enhanced with the increase of buffer gas pressure up to about 20 torr, but showed a decline at higher pressures. The reaction probability increases monotonically with the laser fluence, but the rate of increase diminishes at higher fluences. An attempt was made to simulate the experimental results by the method of energy grained master equation (EGME). From the parameters that fit the experimental data, the average energy loss per collision, $<{\Delta}E>_d$, was estimated for the He, Ar, and $N_2$ buffer gases.