• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.346-346
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• 2012

We investigated electrical and optical properties and chemical states of amorphous In-Ga-Zn-O (a-IGZO) thin films deposited at different substrate temperatures (from room temperature to $300^{\circ}C$). a-IGZO thin films were fabricated by radio frequency magnetron sputtering using $In_2O_3$ : $Ga_2O_3$ : ZnO = 1 : 1 : 1 target, and their electrical and optical properties and chemical states were investigated by Hall-measurement, UV-visible spectroscopy and x-ray photoelectron spectroscopy (XPS), respectively. The data showed that as substrate temperature increased, carrier concentration increased, but mobility, conductivity, transmittance in the shorter wavelength region (>350 nm), and the Tauc-plot-estimated optical bandgap decreased. XPS data indicated that the intensity of In 3d peak compared to Ga 3d peak increased but the intensity of Zn 3d peak compared to Ga 3d decreased, and that, from the deconvoluted O 1s peak, defects or oxygen vacancies and non-quaternary contents increased as the temperature increased. The relative intensity changes of the In, Zn, and O 1s sub-component are suggested to explain the changes in electrical and optical properties.

• Corrosion Science and Technology
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• v.19 no.3
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• pp.109-114
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• 2020

The photo-reflectance of aluminum and AISI 304 stainless steel during cyclic immersion test in 3 wt% NaCl solution was examined in this study. Overall, corrosion was not recognized by a visual inspection or weight measurement up to 310 h. When evaluated, it was noted that the roughness of the specimens did not change significantly. However, localized corrosion, which is located at the vicinity of intermetallic precipitation of aluminum or at the grain boundary of stainless steel, was confirmed by the use of an optical microscope and scanning electron microscopy after tens of hours of utilizing the corrosion test. In this respect, an increase of the peak intensity for metallic Al after 90 h of test, and for metallic Fe after 153 h was detected from the X-ray photoelectron spectra. In this context, it was shown that from the photo-reflectance spectra, the reflection of the visible light from the tested samples was changed noticeably over the test duration. As a result, the intensity of reflected light was decreased up to 90 h ~ 153 h, and thereafter was shown to increase higher than the initial intensity before the corrosion test.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.203.1-203.1
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• 2013

Zinc oxide (ZnO) nanocrystalline thin films on various growth temperatures for active layer and different buffer layer thickness were grown by plasma-assisted molecular beam epitaxy (PA-MBE) on Si substrates. The ZnO active layer were grown with various growth temperature from 500 to $800^{\circ}C$ and the ZnO buffer layer were grown for different time from 5 to 40 minutes. To investigate the structural and optical properties of the ZnO thin films, scanning electron microscope (SEM), X-ray diffractometer (XRD), and photoluminescence (PL) spectroscopy were used, respectively. In the SEM images, the ZnO thin films have high densification of grains and good roughness and uniformity at $800^{\circ}C$ for active layer growth temperature and 20 minutes for buffer layer growth time, respectively. The PL spectra of ZnO buffer layers and active layers display sharp near band edge (NBE) emissions in UV range and broad deep level emissions (DLE) in visible range. The intensity of NBE peaks for the ZnO thin films significantly increase with increase in the active layer growth temperature. In addition, the NBE peak at 20 minutes for buffer layer growth time has the largest emission intensity and the intensity of DLE peaks decrease with increase in the growth time.

• Proceedings of the Safety Management and Science Conference
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• 2012.11a
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• pp.435-443
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• 2012

First introduced in 1962, LED(light-emitting diodes) emitted low-intensity red light, but modern versions are now available across the ultraviolet, visible, and infrared spectrum, many with very high luminance or brightness. As a result, growing importance of potential safety harzards for human. Now when certificated of CE provide that testing through IEC/EN 62471 for any lamp. Korea standard adopted as it IEC 62471:2006, Photobiological safety of lamps and lamp systems without change, but effectiveness is incomplete. In this paper, we introduce analysis and direction that urgently come into effectiveness of KS C IEC 62471 as a national standard specifications.

• Bulletin of the Korean Chemical Society
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• v.31 no.7
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• pp.1956-1962
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• 2010

The formation of diverse spiral waves was studied in a polyacrylamide gel membrane with ruthenium(4-vinyl-4'-methyl-2,2'-bipyridine)bis(2,2'-bipyridine)bis(hexafluorophosphate) by a gas-free Belousov-Zhabotinisky (BZ) reaction system containing 1,4-cyclohexanedione (1,4-CHD). The gel membrane was found to be receptive for observing propagating waves since a clearer wave-train is obtained during a long reaction time without any disturbance from the immobilized metal catalyst which can be dissolved into the highly acidic solution of the BZ system. The distinctive waves in the system basically depend on both $BrO_3$ and 1,4-CHD in the initial phase, and are influenced by the intensity of illumination of visible light.

• Transactions of the Korean Society of Mechanical Engineers
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• v.7 no.4
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• pp.410-416
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• 1983

This study presents the combustion characteristics and flame structure of annular swirling flow when there were changes the equivalence ratio and swirl number of swirling jet of fuelair mixture. The conclusions of this study are as follows; During the investigations in which the change of equivalence ratio and swirl number were studied, three basic shapes of flame were observed in this study. Visible flame lengths of swirling jet results in the decrease with increasing of swirl number and air-fuel ratio of mixture. Radial distribution of flame temperature with strong swirl is higher than that of weak swirl at the same equivalence ratio of mixture. The angle of spread of the annular jet increases with the increase of swirl number. When the swirl intensity is increased in a jet, the decay of concentration of carbon dioxide is decreased with the distance from nozzle exit of burner.

• Korean Journal of Veterinary Research
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• v.36 no.2
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• pp.463-470
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• 1996

The red yeast Phaffia rhodozyma, which contains astaxanthin(3, 3'-dihydroxy-$\beta$, $\beta$-carotene-4, 4'-dione) as its primary carotenoid, was tested as a dietary pigment source for egg yolks of laying hens. When the yeast was fed to laying hens at several concentrations, the intensity of redness in egg yolks was dependent on the yeast concentration in the feed and the deposition period. Addition of P rhodozyma in feed did not cause any visible adverse effect on laying hens.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1993-1996
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• 2011

The vibronically well-resolved emission spectrum was recorded from the corona discharge of precursor 2,3,4-trifluorotoluene in a corona excited supersonic expansion with a pinhole-type glass nozzle using a long-path monochromator in the visible region. From the analysis of the observed spectrum, we found the evidence of the presence of the difluorobenzyl radicals in the corona discharge of the precursor. A possible mechanism is proposed for the formation of difluorobenzyl radicals in the gas phase on the basis of the observed emission intensity of the difluorobenzyl radicals produced.

• Journal of the Korean Applied Science and Technology
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• v.22 no.3
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• pp.228-233
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• 2005

Langmuir-Blodgett(LB) technique can speak the best candidate of the future molecular electronic devices. But, precursor as molecular ultrathin film devices require the bulk property that are influenced by the molecular orientation. So, this device is one of current interest in molecular electronic device development of new materials. In this study, quantitative evaluation of molecular orientation in LB films of polyamic acid alkylamine salt was performed analysis experiment comparing the absorption or transmission intensity of the FT-IR spectrometer and reflection or absorption spectra with UV-visible absorption spectra. It could find that the polar angle(${\theta}$) of the dipole moment appears in about $68^{\circ}$ and the tilting angle of the alkyl chain is about $11.5^{\circ}$.

• Korean Journal of Microbiology
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• v.20 no.1
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• pp.21-26
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• 1982

The disinfection effects of sunlight and predacious microorganisms on enteria of Escherichia coli and Proteus vulgaris were examined in sewage water at 22 to $26^{\circ}C$. The test prganisms were disinfected by 4 to 5 logs during 6-hour a day exposure to sunlight for seven days. The effect was proportional to the light intensity and was proved to be dur to the action of the visible light of short wavelength which can transmit the soft glass of a flask glass. The predacious microorganisms decreased trhe test organisms by about 3 to 4 logs during 7 days. The complex actions of sunlight and predacious microorganisms were variable depending upon the test organisms, but the total effects of those enviromental factors were yet completely understood.