• Laser Solutions
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• v.7 no.3
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• pp.11-24
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• 2004

In automotive industry, light weight vehicle is one of issues because of the air pollution and the protection of environment. Therefore, automotive manufacturers have tried to apply light materials such as aluminum to car body. Aluminum welding using laser has some advantages high energy density and high productivity. It is very important to understand behavior of plasma and keyhole in order to improve weld quality and monitor the weld state. In this study, spectral analysis was carried out to verify the spectrum for plasma which is generated in laser welding of A 6000 aluminum alloy. Two photodiodes which cover the range of plasma wavelength was used to measure light emission during laser welding according to assist gas flow rate and welding speed. Analysis of relationship between sensor signals of welding variables and formation of keyhole and plasma is performed. To determine the level of significance, analysis of variation (ANOVA) was carried out.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.6
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• pp.538-546
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• 2006

We report on characteristics of specially designed inductively-coupled-plasma chemical vapor deposition (ICP-CVD) system for top-emitting organic light emitting diodes (TOLEDs). Using high-density plasma on the order of $10^{11}$ electrons/$cm^3$ generated by linear-type antennas connected in parallel and specially designed substrate cooling system, a 100 nm-thick transparent $SiN_{x}$ passivation layer was deposited on thin Mg-Ag cathode layer at substrate temperature below $50\;^{\circ}C$ without a noticeable plasma damage. In addition, substrate-mask chucking system equipped with a mechanical mask aligner enabled us to pattern the $SiN_x$ passivation layer without conventional lithography processes. Even at low substrate temperature, a $SiN_x$ passivation layer prepared by ICP-CVD shows a good moisture resistance and transparency of $5{\times}10^{-3}g/m^2/day$ and 92 %, respectively. This indicates that the ICP-CVD system is a promising methode to substitute conventional plasma enhanced CVD (PECVD) in thin film passivation process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.316-319
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• 2001

Organic light emitting diodes(OLEDs) with a hole injection layer inserted between Indium-Tin-Oxide(ITO) anode and hole transport layer were fabricated. The effect of plasma treatment on the surface properties of Indium-Tin-Oxide(ITO) anode were studied. The electrical and optical characteristics of the fabricated organic light emitting diodes(OLEDs) were also studied. The diode including of plasma treated ITO substrate and the hole injection layer, which showed the luminance of 5280 $cd/m^{2}$ at 8 V

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.316-319
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• 2001

Organic light emitting diodes(OLEDs) with a hole injection layer inserted between Indium-Tin-Oxide(ITO) anode and hole transport layer were fabricated. The effect of plasma treatment on the surface properties of Indium-Tin-Oxide(ITO) anode were studied. The electrical and optical characteristics of the fabricated organic light emitting diodes(OLEDs) were also studied. The diode including of plasma treated ITO substrate and the hole injection layer, which showed the luminance of 5280 cd/㎡ at 8 V

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.4
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• pp.611-619
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• 2005

The aim of this study was to apply the quantitative light-induced fluorescence(QLF) and use of fluorescein-enhanced QLF method for quantitative assessment of early enamel demineralization in vitro, comparing effectiveness of light sources : argon laser, halogen lamp, light emitting diode (LED) and plasma arc lamp. Sixty extracted teeth were used, prepared by gentle pumicing and coating in an acid-resistant nail-varnish, except for an exposure to a demineralizing solution. Teeth were removed at regular intervals (24, 48 and 72hrs), air-dried and QLF image were taken. Mineral loss, as measured by difference of optical density, was recorded. For dyeenhanced QLF a 0.075% sodium fluorescein dye was applied after QLF examination and mineral loss was recorded. The following result were obtained : 1. Comparing with mean difference of optical density, plasma arc lamp was higher than other light sources in all group (p<0.05). 2. Comparing each group with mean difference of optical density, there was significant different using plasma are lamp and halogen lamp. 3. For use of dye-enhanced QLF, comparing with mean difference of optical density, plasma arc lamp were higher than other light sources in all group(p<0.05). 4. With this model dye-enhanced QLF compared with QLF in optical density, dye-enhanced QLF was higher than QLF in optical density. From the results presented in this paper, it was concluded that plasma light source was more effective compared with other light source for the detection and the quantification of early enamel caries.

• Proceedings of the Optical Society of Korea Conference
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• 1989.02a
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• pp.65-69
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• 1989

Mather type dense plasma focus device was develooped for the feasibili쇼 study in its application to the x-ray lithography. To etermine the electrical characteristics,the temporal begavior of the discharge current and the voltage was measured by using the Rogowski coil and the high voltage probe respectively. The results are 9 $\mu\textrm{s}$ of the period, 18m$\Omega$ of resistance and 0.16$\mu$Η of inductance. The average current sheath velocity was measured by the light signal emitted at the moving plasma sheath. The light signal was detected through two fiber bundles. When the applied voltage was 13 kV and the initial jpressure of argon was 21.8 Pa, the best plasma focus was occurred. The x-ray emission characteristics from the plasma focus was determined by the x-ray pictures taken by pinhole camera. It is focus that the plasma was focused at 1.4 cm distant position above the center electrode and its diameter was about 1.0 m.

• Journal of dental hygiene science
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• v.11 no.4
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• pp.375-380
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• 2011

This study evaluated whether fluoride treatment can affect recovery of the irregularity of enamel surface after tooth whitening with a high concentration of hydrogen peroxide (HP) activated by plasma arc light. A total of 36 bovine teeth stained with coke were used in this experiment. The specimens were classified into following three groups (two different commercial plasma arc groups and a control group without light curing source): (1) 35% HP gel only, (2): 35% HP gel and Plasma arc A, and (3) 35% HP gel and Plasma arc B. To measure color changes and surface morphologies before and after the bleaching, colorimeter and scanning electron microscopy were used, respectively. When the specimens were bleached with hydrogen peroxide and plasma arc lights, the bleaching effect was greater than when only hydrogen peroxide gels were used (Kruskal-Wallis test, p<0.05). In addition, plasma arc B showed the more color changes than plasma arc A (Bonferroni post-hoc test, p<0.05). The surfaces of the teeth treated with fluoride gel after the whitening treatment came to be smooth. Therefore, the results of this study suggested that the fluoride application for patients who got tooth whitening therapy with a high concentration of hydrogen peroxide gels activated by plasma arc light will be effective to recover rough enamel surfaces.

• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.2
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• pp.262-269
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• 2002

The purpose of this study was to compare the effect of distance of light tip to resin surfaces and exposure time on the polymerization of surface and 2 mm subsurface of composite resins cured with two light sources; conventional halogen light (XL 3000, 3M, U.S.A.) and plasma arc light (Flipo, LOKKI, France) and compare the uniformity of polymerization from the center to the periphery of resin surfaces according to polymerization diameter cure with two light sources. From the experiment, the following results were obtained. 1. Difference of relative light intensity decrease in plasma arc light smaller than that of conventional halogen light(p<0.05). 2. In all groups, microhardness of top surfaces was decreased when distance of the light tip to resin surfaces is more than 2mm and increased according to increase of exposure time(p<0.05). 3. Difference of microhardness of the 2mm subsurface was rapidly decreased when distance of light tip to resin surfaces is more than 4mm(except, plasma arc light exposure time of 3 seconds). and the distance of light tip to resin surfaces and exposure time more affected 2mm subsurface rather than top surface(p<0.05). 4. Although exposure time was increased, difference of microhardness of the 2mm subsurface with the distance of light tip to resin surfaces was relatively high in groups between below 4mm and 6 mm(p<0.05). 5. Plasma arc light exposure time of 6 to 9 seconds produced microhardness values and microhardness change according to various distance similar to those produced with 40 to 80 second exposure to a conventional halogen light(p>0.05). 6. In all groups, microhardness was decreased gradually from the center to the periphery of resin surfaces(p<0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.2
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• pp.229-237
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• 2003

The purpose of this study was to compare the effect of exposure time on the polymerization of surface and 2 mm below the surface of light-cured restorative materials cured with three different light sources; conventional halogen light curing unit(XL 3000, 3M, U.S.A.), plasma arc light curing unit(Flipo, LOKKI, France) and light emitting diode(LED) light curing unit(Elipar Free light, 3M, U.S.A.) and compare the uniformity of polymerization from the center to the periphery of resin surfaces according to polymerization diameter cure with three different light sources. From the experiment, the following results were obtained. 1. In Z-100, Plasma arc light exposure time of 6 to 9 seconds and LED light exposure time of 40 to 60 seconds produced microhardness values similar to those produced with 40 second exposure to a conventional halogen light(p>0.05). 2. In Tetric Flow, Plasma arc light exposure time of 9 seconds and LED light exposure time of 40 to 60 seconds produced microhardness values similar to those produced with 40 second exposure to a conventional halogen light(p>0.05). 3. In Dyract AP, Plasma arc light exposure time of 6 to 9 seconds and LED light exposure time of 20 to 40 seconds produced microhardness values similar to those produced with 40second exposure to a conventional halogen light(p>0.05). 4. In Fuji II LC, Plasma arc light exposure time of 9 seconds and LED light exposure time of 20 to 60 seconds produced microhardness values similar to those produced with 40second exposure to a conventional halogen light(p>0.05). 5. Except Fuji II LC, microhardness was decreased from the center to the periphery in all light sources(p<0.05).

• Journal of Photoscience
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• v.9 no.2
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• pp.86-89
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• 2002

Blue light activates proton pump, and creates electrical gradient across the plasma membrane and drives $K^{+}$ uptake in stomatal guard cells. In this presentation, we provide evidence for regulatory mechanisms of the pump and the identification of blue light receptor. The pump is shown to be the plasma membrane H$^{+}$- ATPase and is activated through phosphorylation of the C-terminus. Phosphorylation occurred and 14-3-3 protein bound to the phosphorylation site. The binding of 14-3-3 protein was required for the H$^{+}$-ATPase activation. We also found that phot1 phot2 double mutant does not respond to blue light but other mutants respond to blue light by stomatal opening. However, all these mutants are capable of stomatal opening in the presence of fusicoccin, an activator of the H$^{+}$-ATPase. These results suggest that both photl and phot2 act as blue light receptors in guard cells.d cells.