• Korean Journal of Optics and Photonics
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• v.4 no.2
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• pp.206-211
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• 1993

We carried out the second harmonic generation of low power CW laser diode with maximum power of 30 mW in $LilO_3$ crystals. We used a ring enhancement cavity to increase the second harmonic conversion efficiency. The ring enhancement cavity was Composed of two flat mirrors and two concave mirrors. The focal length of concave mirrors was 25 mm, and 5 mm long and 10 mm long $LilO_3$ crystals were used. We measured the second harmonic power according to the pumping power and compared with theoretical value. We obtained 397 nm second harmonic power of about $6.6{\mu}W$ in 10 mm long $LilO_3$ crystal with the fundumental 794 nm pumping power of 28 mW.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.48-49
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• 2003

저출력 다이오드 여기 레이저에서는 공간모드 특성을 좋게하고 여기 효율을 올리기 위하여 단면 여기 방식을 주로 사용한다. 특히 레이저 다이오드 (LD)로 여기하는 단일모드 녹색광 레이저는 홀로그램, 간섭계, 측정기 등의 응용분야에서 수요가 날로 증가하고 있다. 단일모드 녹색광 레이저의 발진방법으로는 여러 가지가 고안되어 왔다. 먼저 공진기 내부에 얇은 판을 브루스터 (Brewster) 각으로 두어서 편광시키고 이것을 복굴절특성을 가진 Nd：YVO$_4$ 결정과 결합시켜 복굴절 필터 기능을 하게 하는 방법이 있다. (중략)

• Journal of Oral Medicine and Pain
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• v.24 no.3
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• pp.269-280
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• 1999

구강안면동통환자의 발통점에 대한 보존적 치료방법중 저출력레이저의 효과를 평가하기 위해 교근, 측두근과 승모근에 발통점을 가진 치과대학생 69명을 무작위로 분류하여 37명에게는 GaAlAs 반도체 레이저를 조사하였고 나머지 32명은 레이저를 실제로 조사하지 않고 대조군으로 삼았다. 50mW, 820nm의 GaAlAs 반도체 레이저를 이용하여, 4주 동안 첫 주는 2회, 이후 3주 동안 1회씩 총 5회 조사하였고 전자통각계를 이용하여 압력통각역치를 측정한 후 이를 대조군과 비교한 바 다음과 같은 결과를 얻었다. 1. 남녀 및 조사군과 비조사군의 치료 전 압력통각역치는 차이가 없었다. 2. 조사군의 각 근육에서 측정한 압력통각역치는 레이저 치료 2주 후부터 유의하게 높아졌으나 비조사군에서는 차이가 없었다, 3. 비조사군의 치료 전, 후 압력통각역치에는 성 차가 없었다. 반면 종사군의 압력통각역치는 치료 전에는 성 차가 없었으나 치료 후에는 남성이 여성보다 유의하게 높았다.

• Journal of Oral Medicine and Pain
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• v.33 no.1
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• pp.97-103
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• 2008

The purpose of this study was to examine the effect of LLLT on current perception threshold in trigeminal neuralgia patients. Affected site and non-affected site was irradiated by GaAlAs diode laser. Current perception threshold was evaluated with $Neurometer^{(R)}$ CPT/C before and after LLLT. As an outcomes,CPT were obtained. We made a comparision of these values and the results were as follows. 1. There were no significant difference in CPT between affected site and non-affected site before and after LLLT irradiation. 2. There were no significant difference in CPT between affected site and non-affected site after LLLT irradiation. 3. But, CPT values of $A{\beta}$ fiber incresed slightly on both site after LLLT irradiation

• Korean Journal of Optics and Photonics
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• v.7 no.3
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• pp.232-237
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• 1996

A 500 Hz repetition rate excimer laser was developed as light source for pollution lidar. In this paper, the high repetitive output characteristics, the gas flow loop structure, and CR(clearing ratio) characteristics were investigated. Our laser system was constructed compact structure with a streamline gas flow loop and UV preionization. The real gas volume of laser is 10 liter. At 500 Hz repetitive operation, we have obtained average power of 53 watt with KrF laser gas. The variation of laser output, CR, and active volume are $\pm$6.7%, 2.3, and 2.0(H)$\times$1.2(W)$\times$56(L)=134 ㎤, respectively. Laser output power is declined to half at 3$\times$$10^6$ shots.

• The Journal of the Korean dental association
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• v.47 no.3
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• pp.132-145
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• 2009

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.3
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• pp.286-291
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• 2015

LLC resonant converter is used to control laser output power in Nd:YAG laser. Zero voltage switching (ZVS) is implemented to minimize the switching loss which is adopting the LLC resonant converter. In the spot welding processing of metal thin films, the processing quality is decided by the laser beam output energy of single pulse. We decide to the 50 [J] as the single pulse laser beam energy. Laser output power is investigated and experimented by changing the output current. That current is controled by the charging voltage of capacitor. From those results, we obtained the maximum laser output of 58.2 [J] and the conversion efficiency of 2.52% at the discharge voltage of 620V and the discharge current of 861 [A] and the pulse repetition rate of 1 [Hz] at the charging capacitor of 12,000 [${\mu}F$].

• Korean Journal of Optics and Photonics
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• v.11 no.4
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• pp.294-298
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• 2000

The output characteristics of intracavity frequency doubling of laser-diode end-pumped Nd:S-VAP laser were investigated. Nd:S-VAP is suitable for a microchip laser medium, which has a low threshold property because of a very high value of the stimulated emission cross-section and lifetime product. The threshold energy measured was 81 J.ll. The second harmonic output energy measured was $126\mu\textrm{J}$at a pump energy of $2\mu\textrm{J}$. We described for intracavity frequency doubling by using theoretical calculations. Q-switched second harmonic energy measured was $15\mu\textrm{J}$per pulse with a pulse-width of 26 ns. at a pump energy of 2 mJ and an $M^2$ of 1.47 represented a good beam quality. ality.

• Journal of Oral Medicine and Pain
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• v.35 no.1
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• pp.31-39
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• 2010

This study is to observe the bacteriocidal effect of the Low Level Laser (LLL) against oral microorganisms which are related to the occurrence of periodontal diseases and oral malodors. The Porphyromonas gingivalis 2561 (P. gingivalis 2561) and Prevotella intermedia (Pr. intermedia) were treated with photosensitizing substance-toluidine blue O (TBO; C.I. 52040) and then radiated with the LLL which has 650nm wavelength for 1, 2, 3 and 5mins. continuously upon varying distances of 1, 2 and 3cm for each experimental groups. The results are as follows; 1. The P. gingivalis 2561 which was treated with TBO and then radiated with LLL at a distance of 3cm for 1min. showed 99.99% higher antibacterial effect in comparison to the experimental group treated only with TBO. 2. The Pr. intermedia which was treated with TBO and then radiated with LLL at a distance of 3cm for 1min. showed 99.8% higher antibacterial effect in comparison to the experimental group treated only with TBO. 3. The bacteriocidal effect of the P. gingivalis 2561 treated with TBO was found to gradually increase as the radiation time of LLL extended from 1min. to 3min. at 1min. intervals. 4. A slight decrease in bacteriocidal effect of the P. gingivalis 2561 was found as the radiation distance of LLL increased from 1cm to 3cm at 1cm intervals. 5. The bacteriocidal effect of the Pr. intermedia was found to slightly decrease as the radiation distance of LLL increased from 1cm to 3cm at 1cm. intervals. As the results shown above suggest, the bacteriocidal effect of LLL was found to increase as the radiation time extended and the distance shortened. Moreover, even the experimental group radiated with LLL at 3cm distance for 1min. which showed the lowest level of bacteriocidal effect, was found to have 99.8% higher bacteriocidal effect than the experimental group which was treated only with TBO and, therefore, this clearly shows the bacteriocidal effect of LLL against oral microorganisms. Thus, the use of LLL is thought to become very useful for suportive treatment for periodontitis and implantitis, and controlling oral malodors as long as it is used within the limits where there is no side effect.

• The Korean Journal of Pain
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• v.5 no.1
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• pp.44-51
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• 1992

This study examined the microscopic changes following irradiation of infrared low dose laser on injured sciatic nerves of rats. In these days, many clinicians use the low dose laser therapy in pain clinicians use the low dose laser therapy in pain clinic on various fields and dieases. But the basic mechanism and indications were not known completely. Low-dose IR(infrared) laser irradiation applied to a crushed injured sciatic nerve of rats in the right leg in bilaterally inflicted crush injury. The results were as follows 1) There are a little histological differences between laser treated group and nontreated group. 2) Low power IR-laser irradiation, when applied to the injured sciatic nerve, increased vascularization and relatively well conserved tissue organization. 3) There are little histological difference in distal muscle biopsy, but atrophic muscle fibers were seen partially. 4) We found out that more hypertrophic epineurium was present in laser-treated group.