• Title/Summary/Keyword: UV Intensity

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Ultraviolet Inactivation of Escherichia coli in Stainless Steel Cups (스테인리스스틸 컵 내 Escherichia coli의 자외선 살균)

  • Mok, Chulkyoon;Lee, Nam-Hoon
    • Food Engineering Progress
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    • v.13 no.2
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    • pp.122-129
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    • 2009
  • Ultraviolet (UV) is widely used as a sterilizing agent in restaurants and catering facilities in Korea. Efficacy of UV sterilizers (UVS) was investigated against E. coli on the inner bottom of stainless steel cups. UV intensity on the bottom of cups varied widely with the locations of cups in UVS, showing higher values at center while lower values at outskirts. The deviations in UV intensity were remarkable on top shelf, but alleviated as proceeded to middle and bottom shelves. Inactivation of E. coli was proportional to the UV intensity and treatment time, consequently to UV dose, and showed a pseudo-first-order kinetics with tailing. Initial inactivation rate constants ($K_{1}$) deviated with the locations of the cups, while final inactivation rate constants ($K_{2}$) showed comparable values. An equation for the calculation of the proposed UV treatment time was suggested.

The Optical Property of Plasma-treated ZnO Nanorods (플라즈마 처리한 ZnO 나노막대의 광학적 특성)

  • Cho, Hyun-Min;Yu, Se-Gi;Cho, Jae-Won
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.22 no.3
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    • pp.230-234
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    • 2009
  • Hydrogen and Oxygen plasma treatments have been done on sonochemical grow ZnO nanorods by varying treatment temperature and time, The changes(position and intensity) in ultraviolet(UV) peaks and green peaks of photoluminescence(PL) spectroscopy have been measured, Experimental results showed; i) in the case of hydrogen plasma treatment, the blue shift of UV peak and the increase of PL intensity of the UV peak were observed as the increase of the process time and temperature, ii) in the case of oxygen plasma treatment, the red shift of green peak was observed and the ratio of $I_{Green}/I_{UV}$ was also increased, as the increase of the process time and the temperature.

Comparative Sonophotocatalysis and Photocatalysis for Chloroform Degradation (Sonophotocatalysis와 Photocatalysis를 이용한 Chloroform의 광산화)

  • Park, Jae-Hong;Cho, Il-Hyoung
    • Journal of Korean Society on Water Environment
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    • v.21 no.3
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    • pp.263-266
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    • 2005
  • Comparison between photocatalysis (UV+$TiO_2$) and sonophotocatalysis (Sonication+UV+$TiO_2$) were performed in lab-scale experiments for the treatment of chloroform. The effect of operational parameters, i.e., initial chloroform concentration, $TiO_2$ concentration, UV light intensity and sonication time on the degradation rate of aqueous solution of chloroform has been examined. The optimal conditions for photocatalysis and sonophotocatalysis processes were determined: initial chloroform concentration was 25 mg/L, the concentration of $TiO_2$ was 200 mg/L and UV light intensity was $6.630 mW/cm^2$, respectively. The optimal sonication time on sonophotocatalysis process was 90 min. Under the optimal conditions, sonophotocatalysis was effective for inducing faster degradation of the chloroform.

UV emission characteristics of Ne+$N_2$ gas-mixture discharges in AC Plasma Display Panel

  • Baek, Byung-Jong;Hong, Sang-Min;Choi, Kyung-Cheol
    • 한국정보디스플레이학회:학술대회논문집
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    • 2002.08a
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    • pp.586-589
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    • 2002
  • The Ultra Violet(UV) emission characteristics of Neon + Nitrogen gas-mixture discharge was investigated in AC plasma display panel. The firing voltage of Ne+$N_2$ gas-mixture discharge increased with increasing nitrogen concentration. The UV intensity emitted from the gas discharge also increased with increasing nitrogen concentration. The UV efficiency increase with increasing $N_2$ partial pressure at low $N_2$ concentration, and then UV efficiency is saturated at high $N_2$ concentration.

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Photodarkening and Thermal Bleaching Effect in Ge-doped Multicomponent Oxide Glasses by UV Irradiation (자외선 조사에 따른 게르마늄 함유 다성분계 산화물 유리의 광흑화와 열표백화 현상)

  • 이회관;오영석;강원호
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.3 no.3
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    • pp.161-165
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    • 2002
  • Ge-doped rnulticomponent oxide glasses were prepared by a conventional melting method. The change of micro structure in glasses was investigated by using PL (photoluminescence) and ESR (electron spin resonance). Before UV irradiation, the PL intensity increased according to germanium contents, but decreased the intensity as soon as UV irradiation. A changed property was recovered near it original properties when it was annealed. These photodarkening and thermal bleaching effect were observed by ESR intrument. These effect did not change the glass phase but vary only change of micro structure.

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Sensitivity Characteristics of Side-Polished Fiber Optic UV Sensor with Optical Intensity Variation (측면연마 광섬유형 자외선센서의 광강도 변화에 따른 감도특성)

  • Lee, Dong-Rok;Seo, Gyoo-Won;Yoon, Jong-Kuk;Cho, Kang-Min;Kang, Shin-Won
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.41 no.6
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    • pp.53-58
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    • 2004
  • A novel UV sensor was manufactured and characterized using evanescent field coupling between photochromic dye dispersed polymer waveguide and side polished fiber. The spiroxazine (photochromic dye) dispersed polymer was used as planar waveguides. The resonant wavelength was shifted owing to refractive index variation of planar waveguide on exposed UV because of its photo-functional properties. The sensitivities are $1.21{\mu}W/mw$ and $2.75{\mu}W/mw$ when UV intensities increased after exposure times were fixed at 3 seconds and 5 seconds, respectively. Output optical power according to UV intensity increases and saturation time decreases as the intensity of UV radiations increases.

Evaluation of Hydroxyl radical Formation and Energy Distribution in Photolysis Reactor (광반응 반응기 내부의 에너지 분포와 라디칼 생성에 대한 연구)

  • Nam, Sang-Geon;Hwang, An-Na;Cho, Sang-Hyun;Lim, Myung-Hee;Kim, Jee-Hyeong
    • Journal of the Korean Society of Hazard Mitigation
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    • v.11 no.2
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    • pp.179-183
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    • 2011
  • In this study, photochemical effects (OH radical formation) in the photoreactor was investigated to analyze UV-C intensity distribution. In addition, The influence radius of the UV-C lamp was measured at various dose of $TiO_2$ (Degussa P-25). The photoreactor used in this study was bath type reactor which is made by acrylic and the UV-C lamp (SANKYO DENKI, wavelength : 254 nm, Diameter : 2.2 cm, Length : 18.5 cm) was used as photo source. The maximum electric power consumption of the UV lamp was 10.5 W. The OH radical formation by UV-C was measured by KI dosimetry methods. From the results, the effective OH radical formation was occurred under the following condition. The reasonable distance of UV-C lamp is within 13 cm and the intensity of UV-C lamp should be more than 0.367 mW/$cm^2$. Moreover, the concentration of catalyst affects on the influence radius of the UV lamp.

PL degradation utilizing OLED's of photographic images implementation (PL Degradation을 활용한 OLED 소자의 사진 이미지 구현)

  • Suh, Won-Gyu;Moon, Dae-Gyu
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.04a
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    • pp.47-48
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    • 2008
  • 본 연구는 제작된 OLED 소자에 UV의 조사시간에 따른 PL intensity 의 감소와 UV power에 따른 PL degradation 변화에 따라 적절한 UV의 조사조건을 찾아 OLEO 소자의 사진이미지를 구현하고자 하였다. 이러한 조건들로부터 얻어진 OLED 소자의 사진이미지 구현을 통하여 그동안 문제점으로만 여겨졌던 UV에 의한 PL degradation 현상이 문제점만이 아닌 다른 하나의 장점으로 발전되어 다른 분야에서 적용될 수 있다고 기대해본다.

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Degradation of residual pharmaceuticals in water by UV/H2O2 advanced oxidation process (UV/H2O2 고도산화기술을 이용한 수중 잔류의약물질 제거)

  • Park, Chinyoung;Seo, Sangwon;Cho, Ikhwan;Jun, Yongsung;Ha, Hyunsup;Hwang, Tae-Mun
    • Journal of Korean Society of Water and Wastewater
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    • v.33 no.6
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    • pp.469-480
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    • 2019
  • This study was conducted to evaluate the degradation and mineralization of PPCPs (Pharmaceuticals and Personal Care Products) using a CBD(Collimated Beam Device) of UV/H2O2 advanced oxidation process. The decomposition rate of each substance was regarded as the first reaction rate to the ultraviolet irradiation dose. The decomposition rate constants for PPCPs were determined by the concentration of hydrogen peroxide and ultraviolet irradiation intensity. If the decomposition rate constant is large, the PPCPs concentration decreases rapidly. According to the decomposition rate constant, chlortetracycline and sulfamethoxazole are expected to be sufficiently removed by UV irradiation only without the addition of hydrogen peroxide. In the case of carbamazepine, however, very high UV dose was required in the absence of hydrogen peroxide. Other PPCPs required an appropriate concentration of hydrogen peroxide and ultraviolet irradiation intensity. The UV dose required to remove 90% of each PPCPs using the degradation rate constant can be calculated according to the concentration of hydrogen peroxide in each sample. Using this reaction rate, the optimum UV dose and hydrogen peroxide concentration for achieving the target removal rate can be obtained by the target PPCPs and water properties. It can be a necessary data to establish design and operating conditions such as UV lamp type, quantity and hydrogen peroxide concentration depending on the residence time for the most economical operation.

Effect of Ultraviolet Irradiation on Molecular Properties of Ovalbumin (자외선 조사가 Ovalbumin의 분자적 성질에 미치는 영향)

  • Cho, Yong-Sik;Song, Kyung-Bin;Yamada, Koji;Han, Gui-Jung
    • Applied Biological Chemistry
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    • v.51 no.4
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    • pp.276-280
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    • 2008
  • To elucidate the effects of ultraviolet (UV) irradiation on molecular properties of ovalbumin, the molecular weight profile, secondary structure and tertiary structure of proteins were examined after irradiation by UV with 254 nm wavelength for 4, 8, 16 and 32 hrs, respectively. UV irradiation of protein solution caused the disruption on the native state of protein molecules. SDS-PAGE and gel permeation chromatography indicated that radiation caused initial fragmentation of polypeptide chains and as a result subsequent aggregation due to cross-linking of protein molecules. Circular dichroism (CD) study showed that UV irradiation caused the change on the secondary structure resulting in decrease of helical structure or compact denature on structure of protein depending on irradiation period. Fluorescence spectroscopy indicated that irradiation quenched the emission intensity excited at 280 nm. These results suggest that UV irradiation affect the molecular properties of ovalbumin and may have potential as a means to change the antigenicity of protein allergen.