• Composites Research
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• 제27권6호
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• pp.236-241
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• 2014

본 연구에서는 공항 포장용 유지보수 재료로 사용되는 폴리머 콘크리트의 자외선 노출에 대한 기계적 물성 변화를 확인하기 위해 자외선 노출 전/후 시편의 압축강도 및 연성인자의 변화를 평가하였다. 현재 공항 포장용으로 사용되는 폴리머 콘크리트의 비율과 선행연구를 통해 얻은 최적 배합비율을 참고하여 시편을 제작하였다. 자외선 발생 램프의 출력을 고려하여 자연상태에서 노출되는 등가시간을 계산한 후 최대 3년에 해당하는 시간만큼의 등가시간 동안 시편을 노출시켰다. 실험결과, 자외선 노출 자체는 재료물성에 거의 영향을 주지 않았으며, 자외선 노출에 따른 온도상승에 의한 재료물성 변화가 주로 관찰되었다. 자외선에 의해 발생된 열에 노출된 후 모든 시편에서 인성은 감소하고, 압축강도는 증가하는 경향을 나타내었다.

• 대한기계학회논문집A
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• 제24권9호
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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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• 제2권1호
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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.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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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.

• 한국신뢰성학회지:신뢰성응용연구
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• 제7권4호
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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.

• 대한화장품학회지
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• 제26권1호
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• pp.41-58
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• 2000

최근 환경오염으로 인한 지구오존층의 파괴로 자외선의 지표면의 도달 량이 증가하고 그로 인한 인간에 대한 피해가 증가하고 있다 . 과도한 자외선의 피부에 대한 직접적인 노출은 피부에 많은 문제점을 야기하므로 일차적으로 자외선차단제를 이용하여 인체에 대한 직접적인 피해를 최소화 해야한다 . 현재 자외선 차단제는 유기자외선흡수제와 무기자외선산란제가 많이 사용이 되는데 적은량으로도 효과가 높은 유기자외선차단제는 사용 시 주의를 요하므로 국가별로 사용량과 사용여부에 대하여 규제를 하고 있다. 본 연구에서는 플라보노이드류 ,알카로이드류 같은 자외선 흡수 성분을 함유한 식물중 UV/vis spectrophotometer 에서 자외선 흡수 peak을 나타내는 금은화 , 포공영, 녹차 , 황금추출물을 이용하여 화장품의 자외선 흡수제로서의 사용가능성여부를 조사하였다. 또한 식물추출물이 가진 자극성 성분과 오염성, 그들이 가진 유효성분들을 보호하고자 실리콘을 이용한 겔화를 시도하였다 . 자연친화적인 천연물로써 식물추출성분을 이용 유기자외선흡수제의 사용량을 줄이는 자외선홉수보조제로서 가능성을 보여주었다.

• 천문학논총
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• 제15권spc1호
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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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 D
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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.

• 한국전기전자재료학회논문지
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• 제19권8호
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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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• 제3권2호
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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.