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

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Generation of High Pretilt Angle in a Cell with Oblique non-polarized UV Light Irradiation on Polyimide Surface (폴리이미드막표면위에 경사진 자외선 조사를 이용한 액정셀에서의 고프리틸트각의 발생)

  • 서대식;한정민
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.6
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    • pp.481-485
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    • 1998
  • We investigated the generation of high pretilt angle for nematic liquid crystal (NLC) in a cell with obilique non-polarized ultraviolet (UV) light irradiation on mixtured polyimide surface. It was found that the monodomain alignment of NLC is obtained with an angle of incidence of 75∼85 degrees on PI surface. We consider that the monodomain alignment of NLC is attributed to anisotropic dispersion force effect to photo-depolymerization of polymer. We successfully observed that the pretilt angle of NLC is generated above 5 degree with an angle of incidence of 75∼85 degrees. It is considered that the pretilt angle generation NLC is attributed to interaction between the LC molecules and the polymer surfaces.

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Pretilt Angle Generation and EO Performance in MLC with Polarized UV Light Irradiation Polyimide surface (폴리이미드막 표면에 직선 편광된 UV광 조사에 의한 프리틸트각 발생과 전기광학특성)

  • 서대식;이정호;이창훈
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.10
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    • pp.878-884
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    • 1998
  • We have investigated that the monodomain alignment of nematic liquid crystal (NLC) is obtained with polarized ultraviolet(PUV) light irradiation on polyimide (PI) surface. The LC alignment capability increases with increasing the UV light irradiation time. The polarized UV light irradiation on oblique angle of 60。 irradiated on PI surface rotated by 90。 at 10 min. after being normally irradiated on PI surface at 30 min., the generated pretilt angle of NLC is about 2.5。. The pretilt angle of NLC is attributed to the interaction between the LC molecules and the asymmetric triangular structure of polymer surface due to photo-depolymerization of polymer with the oblique UV light on PI surface. The voltage -transmittance and response time characteristics of photo-aligned twisted nematic (TN)-LCD with UV light irradiation time 60 min. were almost same in comparison with the rubbing-treated TN-LCD.

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Appropriate Digital Camera System for Digital Ultraviolet Photography (디지털 자외선 사진을 위한 적정 디지털 카메라 시스템)

  • Lee, Young-Kyu;Har, Dong-Hwan
    • The Journal of the Korea Contents Association
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    • v.10 no.7
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    • pp.40-48
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    • 2010
  • Reflected-Ultraviolet photography is applied to the evidence of crime, Archaeology, and Dermatology. In the past, Ultraviolet photography was done with standard black-and-white film. Because emulsion of film is more sensitive to near UV light than CCD(Charge Coupled Device) or CMOS(Complementary Metal-Oxide-Semiconductor)of digital camera. In this research, we purpose to improve qulity of ultraviolet photographs and to find out the best alternative digital camera by utilizing a cunsumer digital camera. To achieve theses, we removed IR cutoff filter from digital camera. And by using modified UV pass filter, we verified the increase of image resolution of digital ultraviolet photographs. Also, we analyze reproducibility of digital ultraviolet photographs according to type, size, pixel of image sensor. Furthermore, this research resulted in the development of an practical digital camera system by utilizing a cunsumer digital camera. Eventually, it will contribute to practical use in the various field of digital ultraviolet photographs

Electro-optic Characteristics of External Electrode Fluorescent Lamps Depending on the Glass Thickness

  • Yu, Mi-Yeon;Ko, Jae-Hyeon;Kim, Young-Youb;Kim, Kyung-Ran
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.703-706
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    • 2009
  • The external electrode fluorescent lamp(EEFL) has recently been applied to backlight of LCD TV as a new light source. The dependence of the electro-optic characteristics of the EEFL used in direct-lit backlights on the glass thickness was examined in detail, and the ultraviolet(UV)-light efficiency was estimated. It was found that the lamp efficiency became larger as the glass thickness decreased if other conditions were the same.

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Novel Phosphors for UV Excitable White Light Emitting Diodes

  • Liu, Ru-Shi;Lin, Chun-Che;Tang, Yu-Sheng;Hu, Shu-Fen
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.1343-1346
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    • 2008
  • $KSrPO_4$ and $Sr_3(Al_2O_5)Cl_2$ phosphors doped with $Eu^{2+}$ emit a blue and orange-yellow luminescence under ultraviolet (UV) excitation at ~ 400 nm, respectivel, which can be used for making white light emitting diodes.

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Electro-optical properties of photo-aligned VA-LCD by irradiation of unpolarized UV light. (비편광 UV조사에 의한 광배향 VA-LCD의 전기광학특성)

  • 박두석;서대식
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.545-548
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    • 1999
  • The electro-optical characteristics of photo-aligned vertical-alignment (VA)-liquid crystal display (LCD) with non-polarized ultraviolet (UV) light irradiation of 45\`on homeotropic polyimide (Pl) surface were investigated. LC alignment on photo-aligned VA-LCD is attributed to photo-depolymerized reaction of the polymer with non-polarized UV light irradiation on PI surface. We had good voltage-transmittance (V-T) characteristics of photo-aligned VA-LCD. The response time of photo-aligned VA-LCD was slower than that of the rubbing-aligned VA-LCD. Finally, we suggest that the slow response time of photo-aligned VA-LCD depends on the LC domain.

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Incident angle dependence of pretilt and LC alignment with oblique polarized UV light irradiation on polymer surface (고분자막에 직선편광된 UV광의 경사진 조사법을 이용한 액정배향 및 프리틸트각의 조사각도 의존성)

  • Seo, Dae-Shik;Yu, Mun-Sang;Hwang, Jeong-Yeon;Park, Tae-Kyu
    • Proceedings of the KIEE Conference
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    • pp.1395-1397
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    • 1998
  • In this paper, we studied the liquid crystal(LC) alignment and generation of pretilt angle in nematic (N) LC with oblique p-wave polarized ultraviolet (UV) light irradiation on the two kinds of the polyimide (PI) surface. The monodomain alignment of NLC is obtained with oblique p-wave polarized UV light irradiated on PI surface at 5$\sim$60min. We obtained that the pretilt angles of the NLC is generated about $2.1^{\circ}$ with angle of incidence of $30^{\circ}$ at 20min. Also, the pretilt angle of NLC decreases with increasing the imidization temperature on PI surface.

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Characteristics of Erythemal Ultraviolet Irradiance operating at Korea Meteorological Administration (기상청에서 운용 중인 지역별 지표 홍반자외선(EUV-B) 복사의 특성)

  • Hong Gi-Man;Choi Byoung-Cheol
    • Journal of Korean Society for Atmospheric Environment
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    • v.22 no.2
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    • pp.223-233
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    • 2006
  • We analyzed the monthly and seasonal mean of the daily Erythemal Ultraviolet-B (EUV-B, $280{\sim}320nm$) irradiance operating in Pohang, Anmyeon, Gosan, Mokpo and Kangnung with UV-Biometer (Solar Light Co., Model No. 501) at clear-sky noon during the period from 1999 to 2004. Also, we investigated the seasonal and regional characteristics for the UV index over the Korean Peninsula. The daily maximum occurred near solar southing time and the highest monthly accumulated EUV-B irradiance appeared in July and August at each regional observatory. The monthly mean value of the clear-sky EUV-B irradiance in Pohang, Anmyeon, Gosan, Mokpo and Kangnung showed 196.6, 161.8, 221.9, $171.5mWm^{-2}\;and\;179.7mWm^{-2}$ near noon in July respectively. The annual mean value of the daily accumulated EUV-B irradiance in Pohang, Anmyeon, Gosan, Mokpo and Kangnung were 1.8, 2.1, 2.2, $1.8kJm^{-2}\;and\;1.5kJm^{-2}$ respectively. The UV Index (UVI) showed above UVI 7(High) more than 90 days during one year over the Korean Peninsula.

Effects of supplementary UV-B radiation on growth and protein biosyntheses in rice (Oryza sativa L.)

  • Takeuchi, Atsuko;Hidema, Jun;Kumagai, Tadashi
    • Journal of Photoscience
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    • v.9 no.2
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    • pp.332-334
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    • 2002
  • We examined the effects of supplementary ultraviolet-B (UV-B) radiation on the changes in synthesis and degradation of ribulose-I, 5-biphosphate carboxylase /oxygenase (Rubisco) and light-harvesting chlorophyll a/b binding protein of PSII (LHCII), as well as mRNA levels for small and large subunits of Rubisco (rbcS and rbcL, respectively) and LHCII (cab) with leaf age in UV-sensitive rice (Norin I) and UV-resistant rice (Sasanishiki). Both Rubisco and LHCII were actively synthesized until the leaf had fully expanded, and then decreased with leaf age. Synthesis of Rubisco, but not LHCII, was significantly suppressed by UV-B in Norin 1. The degradation of Rubisco was enhanced by UV-B around the time of the leaf maturation in the two cultivars. The levels of rbcS and rbcL were reduced by UV-B at the early leaf stages after emergence in both cultivars. The level of cab was first present at the highest level in the two cultivars, but drastically decreased due to UV-B treatment immediately after leaf emergence in Norin 1. It was proved that synthesis and degradation of Rubisco and LHCII greatly changed with leaf age: Rubisco synthesis was significantly suppressed by supplementary UV-B radiation at the transcription step during the early leaf stages. It was also suggested that the difference between the two rice cultivars in sensitivity to UV-B in the synthesis of Rubisco might be due to the specific suppression not only after transcription but also at transcription.

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Effects of Ethyl methanesuifonate and Ultraviolet light on Induction of the Adaptive Response in Chinese Hamster Ovary and Sarcoma 180 Cells

  • Kim, Gyoo-Cheon;Lee, Dong-Wook;Shin, Eun-Joo;Um, Kyung-Il
    • Environmental Mutagens and Carcinogens
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    • v.16 no.1
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    • pp.19-23
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    • 1996
  • This study was performed by the sister chromatid exchanges (SCEs) and micronuclei (MN) assays to investigate the adaptive response to ultraviolet light (UV) or ethyl methanesulfonate (EMS) in Chinese hamster ovary (CHO) and Sarcoma 180 (S180) cells. The pretreatment with 1 J/m$^2$ UV or 2 mM EMS decreased the frequency of SCEs induced by the treatment with 5 J/m$^2$ UV or 8 mM EMS in CHO cells. The pretreatment with UV (1 or 2 J/m$^2$) or EMS (1, 2 or 3 mM) did not affect the SCEs induced by the treatment with 7 J/m$^2$ UV or 10 mM EMS in S180 cells. On the other hand, the pretreatment with 1 J/m$^2$ UV or 2 mM EMS decreased the frequency of MN induced by the treatment with 5 J/m$^2$ UV or 8 mM EMS in CHO cells. The pretreatment with UV (1 or 2 J/m$^2$) or EMS (1, 2 or 3 mM) did not affect the frequency of MN induced by the treatment with 7 J/m$^2$ UV or 10 mM EMS in S180 cells. It is suggested that there are adaptive responses at the level of chromosome and micronuclei to UV and EMS in CHO cells.

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