• Title, Summary, Keyword: UV (ultraviolet) light

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Relationship between the pretilt angle generation and the polarization component with linearily polarized UV light irradiation on polymer surface. (직선편광된 UV광을 폴리이미드막에 조사한 경우의 프리틸트각의 발생과 편광성분의 상호관계)

  • Seo, Dae-Shik;Park, Doo-Seok;Han, Jeong-Min
    • Proceedings of the KIEE Conference
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    • pp.1391-1394
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    • 1998
  • In this paper, we investigated the generation of pretilt for nematic liquid crystal (NLC) in a cell with linearly polarized ultraviolet (UV) light irradiation on polyimide (PI) surface. The pretilt angle of the NLC increases with increasing the incident angle in the cells with S-wave polarized UV light irradiation on PI surface. It is considered that the pretilt angle of the NLC increased due to decreasing the UV light intencity. We suggest that the pretilt angle of the NLC is attributed to asymmetry triangular of the polymer surface with S-wave polarized UV light irradiation on PI surface. Also, we consider that the asymmetry triangular of the Polymer not formed with P-wave polarized UV light irradiation on PI surface. Therefore, the pretilt angle of the NLC is attributed to asymmetry triangular of the polymer surface with UV light irradiation on PI surface.

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Hazards Caused by UV Rays of Xenon Light Based High Performance Solar Simulators

  • Dibowski, Gerd;Esser, Kai
    • Safety and Health at Work
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    • v.8 no.3
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    • pp.237-245
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    • 2017
  • Background: Solar furnaces are used worldwide to conduct experiments to demonstrate the feasibility of solar-chemical processes with the aid of concentrated sunlight, or to qualify high temperature-resistant components. In recent years, high-flux solar simulators (HFSSs) based on short-arc xenon lamps are more frequently used. The emitted spectrum is very similar to natural sunlight but with dangerous portions of ultraviolet light as well. Due to special benefits of solar simulators the increase of construction activity for HFSS can be observed worldwide. Hence, it is quite important to protect employees against serious injuries caused by ultraviolet radiation (UVR) in a range of 100 nm to 400 nm. Methods: The UV measurements were made at the German Aerospace Center (DLR), Cologne and Paul-Scherrer-Institute (PSI), Switzerland, during normal operations of the HFSS, with a high-precision UV-A/B radiometer using different experiment setups at different power levels. Thus, the measurement results represent UV emissions which are typical when operating a HFSS. Therefore, the biological effects on people exposed to UVR was investigated systematically to identify the existing hazard potential. Results: It should be noted that the permissible workplace exposure limits for UV emissions significantly exceeded after a few seconds. One critical value was strongly exceeded by a factor of 770. Conclusion: The prevention of emissions must first and foremost be carried out by structural measures. Furthermore, unambiguous protocols have to be defined and compliance must be monitored. For short-term activities in the hazard area, measures for the protection of eyes and skin must be taken.

A clean technology development using the molybdenum dissolution reaction with hydrogen peroxide/UV/Ozone ($오존/UV/H_2O_2$를 이용한 몰리브덴(Mo) 용해 반응에 따른 청정기술 개발에 관한 연구)

  • 김재우;홍종순;신대윤
    • Journal of environmental and Sanitary engineering
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    • v.14 no.4
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    • pp.143-149
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    • 1999
  • In the tungsten industry as light source material, tungsten filament which used as light source material could form after molybdenumwire which used as the center supporter for coil shape tungsten wire was removed. This process uses hydrogen peroxide, Ozone and UV(Ultraviolet)Lamp, for the quantity of hydrogen peroxide decrease. The results were as follows : 1. An incandescent electric Lamp type : FL(FL-20) type : A standard of commodity (P.W.: $19{\pm}1.0mg$, $C.R:4.5{\pm}0.3{\Omega}$) 1) Only hydrogen peroxide treated ; Reaction Time : 65Min., P.W.: 18.60mg, $C.R.:4.60{\Omega}$ 2) Ozone/Ultraviolet/70% of hydrogen peroxide; Reaction Time : 64Min., P.W.: 18.61mg, C.R.: $4.61{\Omega}$ 2. A Fluorescent Lamp Type : GLS(GLS-40) Type : A standard of commodity(P.W.: $11.8{\pm}0.2mg$$65{\pm}1.5{\Omega}$) 1) Only hydrogen peroxide treated ; Reaction Time: 72Min, P.W.:11.88mg, C.R.: $65.62\Omega$ 2) Ozone/Ultraviolet/70% of hydrogen peroxide;Reaction Time:71Min., P.W.:11.88mg, C.R.: $65.63\Omega$

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Ultraviolet and visible light detection characteristics of amorphous indium gallium zinc oxide thin film transistor for photodetector applications

  • Chang, Seong-Pil;Ju, Byeong-Kwon
    • International journal of advanced smart convergence
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    • v.1 no.1
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    • pp.61-64
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    • 2012
  • The ultraviolet and visible light responsive properties of the amorphous indium gallium zinc oxide thin film transistor have been investigated. Amorphous indium gallium zinc oxide (a-IGZO) thin film transistor operate in the enhancement mode with saturation mobility of $6.99cm^2/Vs$, threshold voltage of 13.5 V, subthreshold slope of 1.58 V/dec and an on/off current ratio of $2.45{\times}10^8$. The transistor was subsequently characterized in respect of visible light and UV illuminations in order to investigate its potential for possible use as a detector. The performance of the transistor is indicates a high-photosensitivity in the off-state with a ratio of photocurrent to dark current of $5.74{\times}10^2$. The obtained results reveal that the amorphous indium gallium zinc oxide thin film transistor can be used to fabricate UV photodetector operating in the 366 nm.

EFFECTS OF ULTRAVIOLET LIGHT AND NUCLEIC ACID DERIVATIVES ON THE REPRODUCTIVE RATE OF AZOTOBACTER (Azotobacter의 증진율에 미치는 자외선 및 nucleic acid derivatives의 영향)

  • Lee, Min-Jai
    • Journal of Plant Biology
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    • v.3 no.2
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    • pp.1-5
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    • 1960
  • Azotobacter is isolated from soil and its purified species is identified as A. chroococcum. The survival rate of Azotobacter irradiated with UV light is measured, and the reproductive rates of the survivals are calculated. In general, not only the survival rate, but also the length of the generation time of the survival progeny is inversely proportional to the irradiated dose of UV light. The reproduvtive rate of Azotobacter is increased with the exogeneous treatment of nucleic acid derivatives.

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광촉매 반응에 의한 환경호르몬 분해특성

  • 박재홍;안상우;장순웅
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • pp.358-361
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    • 2004
  • The photocatalytic degradation of Endocrine Discruptors, dibuthyl phthalate(DBP) has been investigated over TiO$_2$ photocatalysts irradiated with a ultraviolet (UV) light. The effect of operational parameters, i.e., reaction time, light intensity, pH and additive on the degradation rate of aqueous solution of Endocrine Discruptors has been examined. Results show that the employment of efficient photocatalysts and the selection of optimal operational parameters may lead to degradation of Endocrine Discruptors solutions.

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Realization of Static Image on OLEO using Photoluminescence Degradation (PL Degradation을 활용한 OLED 소자의 사진 이미지 구현)

  • Suh, Won-Gyu;Moon, Dae-Gyu
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.21 no.9
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    • pp.859-862
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    • 2008
  • We have realized static image on organic light emitting diodes (OLEDs) using photoluminescence degradation. Ultraviolet (UV) was irradiated to the glass side of device. UV power was 350 Wand the wavelength was 365 nm. The UV irradiation gives rise to the degradation of photoluminescence. Due to the degradation, the current density-voltage curve was shifted to the higher voltage side and the luminescence was also degraded by the current and photoluminescence drop. The negative imaged films were prepared to control the transmittance of UV. The UV light was passed through the film. By this method, the film image was transferred to the device with reversed image and the static image was realized on the OLED.

Effects of UV light irradiation condition and imidization temperature for the generation of pretilt angle on polyimide surfaces (폴리이미드 표면에서의 프리틸트각 발생에 대한 UV조사 조건과 이미드화온도의 영향)

  • Yu, Mun-Sang;Seo, Dae-Shik;Hwang, Jeoung-Yeon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.61-64
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    • 1998
  • We have investigated the effects of ultraviolet (UV) light irradiation condition and imidization temperature for the generation of pretilt angle in nematic liquid crystal (NLC) on the two kinds of the polyimide (PI) surfaces. High pretilt angle of NLC is generated with oblique p-polarized UV light irradiation of 30$^{\circ}$ on PI surface for 20 min. Also, the high pretilt angle of NLC is generated with oblique p-polarized UV light irradiation of 10-30$^{\circ}$ on PI surface at 20min. The pretilt angle of NLC decreases with increasing the imidization temperature on all rubbed PI surfaces ; the pretilt angle of NLC with oblique p-polarized UV light irradiation of 30$^{\circ}$on PI surface decreases with increasing the imidization temperature. The high pretilt angle of NLC is observed due to high photo-depolymerization reaction by low surface energy at low imidization temperature. We suggest that the pretilt angle of NLC is strongly attributed to the photo-depolymerization reaction with the UV light irradiation condition and imidization temperature.

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Downregulation of bcl-xL Is Relevant to UV-induced Apoptosis in Fibroblasts

  • Nakagawa, Yuki;Okada, Seiji;Hatano, Masahiko;Ebara, Masaaki;Saisho, Hiromitsu;Tokuhisa, Takeshi
    • BMB Reports
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    • v.35 no.5
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    • pp.452-458
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    • 2002
  • Exposure to ultraviolet light (UV) induces apoptosis in mammalian cells, The caspase group of proteases is required for the appotosis. This pathway is initiated by a release of cytochrome c from the mitochondria into the cytosol. Several Bcl-2 family proteins can regulate the release of cytochrome c by stabilizing the mitochondrial membrane. Here we show that expression of the endogenous bcl-xL was strongly downregulated in NIH3T3 cells within 2 h after UV-C irradiation, and that of bax was upregulated from 8 h after irradiation. Apoptosis was induced in more than 50% of the NIH3T3 cells 48 h after irradiation. Constitutive overexpression of bcl-xL in NIH3T3 cells protected the UV-induced apoptosis by preventing the loss of mitochondrial membrane potential and the activation of caspase 9. There results suggest that downregulation of Bcl-xL is relevant to UV-induced apoptosis of tibroblasts.

Evaluation of Electrical Properties of IZO Thin-Film with UV Post-Annealing Treatment Time (IZO 박막 트랜지스터의 UV를 이용한 후열처리 조사 시간에 따른 전기적 특성 평가)

  • Lee, Jae-Yun;Kim, Han-Sang;Kim, Sung-Jin
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.33 no.2
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    • pp.93-98
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    • 2020
  • We investigated the effect of a post-annealing process using ultraviolet (UV) light on the electrical properties of solution-processed InZnO (IZO) thin-film transistors (TFTs). UV light was irradiated on IZO TFTs for different time periods of 0s, 30s, and 90s. We measured transfer and retention stability curves to evaluate the performance of the fabricated TFTs. In addition, we measured height, amplitude, and phase AFM images to analyze changes in the surface and morphology of the devices. AFM measurements were performed by setting the drive amplitude of the cantilever tip to 47.9 mV in tapping mode, then dividing the device surface into 500 nm × 500 nm. In the case of IZO TFT irradiated with UV for 30s, the electron mobility and Ion/Ioff ratio were improved, the threshold voltage was reduced by approximately 2 V, and the subthreshold swing also decreased form 1.34 V/dec to 1.11 V/dec.