• Composites Research
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• v.27 no.6
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• pp.236-241
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• 2014

This paper aims to evaluate material property variation of polymer concretes under ultra-violet exposure condition. The components and mixing ratio of the polymer composite specimens were determined by the previous research results. The equivalent UV exposure time was calculated with the consideration of the power of metal halide lamp and maximum 3 years were selected for the experiments. From the tests, it was found that the generated heat during UV exposure affected much the material properties of polymer concrete by means of post cure. As a result, the compressive strength increased and ductility factor decreased.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2371-2380
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• 2000

In this paper, we developed the proximity exposure system with the vertical structure of glass and mask stage to minimize the mask's warp caused by the pull of gravity. This system, which canirradiate the ultra violet through 1440 H 850 $\textrm{mm}^2$ and 1330X 1015 $\textrm{mm}^2$ exposure area, has the followingcharacteristics. The glass stage can be inclined by 80 degrees at vertical structure to load substrate withsafety on it. When the glass stage is the vertical state, the gap control, alignment control and exposureof ultra violet are executed. So, it enhances the pattern uniformity by minimizing the mask's warp. Theglass stage can also control the gap between the mask and the substrate by the coarse and fine motioncontrol. The mask stage can adjust the posture of photomask to the position of substrate by imageprecessing method. The galss stage for the gap control and the mask stage for the alignment aredesigned independently for each function.

• Journal of Pharmaceutical Investigation
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• v.2 no.1
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• pp.58-62
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• 1972

The stabillities of taurine, niacinamide, and pyridoxine hydrochloride under exposure to ultra violet radiation in liquid preparations were studied. And sterilization effects for E. coli in both water and liquid preparations were also comparatively evaluated. The above mentioned organic compounds were stable under this experimental conditions and viable count of E. coli reveals that organic compounds dissolved in solution display protective action for microorganisms under UV-irradiation.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.333-336
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• 2006

In general, polymer materials undergo degradation when exposed to ultraviolet radiation, which can cause dissociation of chemical bonds. FRP composites which are used in strengthening existing structure are usually adhered on the concrete surface, its mechanical properties as well as appearance such as color, surface conditions are affected by sunlight and expecially ultraviolet light. In this study, variations of tensile strength after exposure for certain period of time through accelerated exposure by Xe arc methods specified in KS F 2274 are measured in order to examine strength degradation characteristics of FRP composite. As a result of ultraviolet light test for FRP composite after accelerated exposure for 0, 500, 1000, 1500 hour, discoloration of FRP composite occurs according to the passage of time. But, few strength degradations of FRP composite are observed due to exposure of ultraviolet ray with an small variation of tensile strength.

• Journal of Applied Reliability
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• v.7 no.4
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• pp.173-181
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• 2007

Out door exposure to daylight and weather climate conditions can cause adverse effect on the properties of automotive plastic materials. The effects of sunlight exposure, especially ultra violet (UV) radiation, can break down the chemical bonds in a polymeric material. This degradation process is called photo-degradation and ultimately leads to color changes, cracking, chalking, the loss of physical properties and deterioration of other properties. To explore the effect of sunlight exposure on the automotive materials, this study investigated photo-oxidation degree and surface property change of molding parts by analytical methods. For the further study, accelerated weathering test methods are proposed, which can correlate with out door weathering, to predict long term performance of automotive plastic materials.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.26 no.1
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• pp.41-58
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• 2000

Recently the harmfulness of W radiation is in creasing due to encironmental pollution. Environmental population may also play a role in global decrease of ozone layer, A major consequence of ozone depletion is increase in solar ultra violet radiation received at the earth's surface excessive exposure to W radiation cause a lot of problems in our skin. Plant extract that possess antioxidative activities has been reported to retard the oxidation process in product to which they have been added. Plant are alived under solar light. So it is expect the plants have so many protection mechanisms and UV absorbent ingredients against ultra violet radiation such as UVB, UVA. Plant extract which were flavonoids, alkaloids and others could be transformed into UV absorber by chemical modification. Therefore with the aim of finding alternative natural absorber that can safely be used in cosmetic, we have screened various extract for their UV absorbent effect. Thus, the cosmetic safety against human skin, antimicrobial effects and others could be improved by using the silicon.

• Publications of The Korean Astronomical Society
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• v.15 no.spc1
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• pp.127-132
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• 2000

The purposes of spectroscopy in astronomy are to measure the radiation flux of the spectroscopic emission or absorption line and to measure the dynamical parameters of the line profile. In order to use an appropriate instrument for the scientific purpose, we need to understand the characteristics of various spectrometers, e.g., a prism spectrometer, a grating spectrometer, and a Fabry-Perot spectrometer (FPS), which are being used in ultra-violet, optical, and infrared bands. The Fabry­Perot spectrometer is not very popular compared to the grating spectrometer, because of its complex and tricky operations. The Fabry-Perot spectrometer, however, can get a two-dimensional image at one exposure, so we can study radiation mechanisms and dynamical properties of extended sources, e.g., clusters, nebula, and galaxies.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1413-1415
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• 1998

This study deals with the aging effect of EPDM, to understand the surface hydrophobicity mechanism and electrical characteristics due to UV irradiation and salt fog. A mini chamber was fabricated for this test. The specimen was subjected a specific aging cycle. With the result of various analysis methods and investigation, we could make a advanced understanding to the aging mechanism, like as the relationships of the surface morphology and surface electrical characteristics.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.8
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• pp.758-763
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• 2006

We has been studied the thin film encapsulation effect for organic light-emitting diodes (OLED). To evaluate the passivation properties of the passivation layer materials, we have carried out the fabrication of green light emitting diodes with ultra violet(UV) light absorbing polymer resin, $SiO_2,\;and\;SiN_x$, respectively. From the measurement results of shrinkage properties according to the exposure time to the atmosphere, we found that $SiN_x$ thin film is the best material for passivation layer. We have investigated the emission efficiency and life time of OLED device using the package structure of $OLED/SiN_x/polymer$ resin/Al/polymer resin. The emission efficiency of this OLED device was 13 lm/W and life time was about 2,000 hours, which reach 95 % of the performance for the OLED encapsulated with metal.

• Journal of Korean Vacuum Science & Technology
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• v.3 no.2
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• pp.116-120
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• 1999

Possible role of hydrogen atoms on the formation of microcrystalline silicon films was schematically investigated using a plasma enhanced chemical vapor deposition system. A layer-by-layer technique that can alternate deposition of ${\alpha}$-Si thin film and then exposure of H2 plasma was used for this end. The experimental process was extensively carried out under different hydrogen plasma times (t2) at a fixed number of 20 cycles in the deposition. structural properties, such as crystalline volume fractions and grain shapes were analyzed by using a Raman spectroscopy and a scanning electron microscopy. Electrical transports were characterized by the temperature dependence of the dark conductivity that gives rise to the calculation of activation energy (Ea). Optical absorption was measured using an ultra violet spectrophotometer, resulting in the optical energy gap (Eopt). Our experimental results indicate that both of the hydrogen etching and the structural relaxation effects on the film surface seem to be responsible for the growth mechanism of the crystallites in the ${\mu}$c-si films.