• Title, Summary, Keyword: UV wavelength

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Removal of Volatile Organic Compounds by Photo-Catalytic Oxidation

  • Lee, Byeong-Kyu;Jung, Kwang-Ryun
    • Journal of Korean Society for Atmospheric Environment
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    • v.16 no.E
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    • pp.39-46
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    • 2000
  • Volatile Organic Compounds (VOCs) are considered as the precursors of atmospheric ozone and photochemical smog formation. In particular, chemical plants have produced a lot of VOCs and thus they have been forced to reduce or remove air emissions from the on-site chemical facilities. For the effective removal of VOCs produced in the chemical plants, the authors employed a titanium oxide(TiO$_2$) mediated photo-catalytic oxidation method. The initiation methods employed in this study to produce oxygen radicals for th photo-catalytic oxidation of the VOCs were Ultra-Violet(UV), Non-Thermal Plasma(NTS), and a combination of Uv and NTP. This study focused on a comparison of the removal efficiencies of VOCs as a function of the initiation method such as NTP and/or UV techniques. Removal efficiency change of VOCs as was investigated as a function of the wavelength of the UV lamp(254, 302, and 365 nm) and the degree of TiO$_2$ coating (10 and 30%). In this study, it was identified that removal efficiencies if the VOCs under the normal air environment were much better than those under the nitrogen gas environment containing small amount of oxygen. Removal efficiency by NTP technique was much better than the UV or the combination of UV and NTP techniques. In a comparison if UV wavelengths employed, it was found that shorter wavelength showed better removal efficiency, compared with longer ones. When the removal efficiencies of VOCs were compared in terms of the degree of TiO$_2$ coating, the higher TiO$_2$coating showed better removal efficiency that the lower TiO$_2$ coating

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UV Optical Solutions for Thin Film Processing and Annealing Research

  • Delmdahl, Ralph;Shimizu, Hiroshi;Dittmar, Mirko;Fechner, Burkhard
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.246-249
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    • 2009
  • A compact, flexible family of UV laser material processing systems has been developed to drive advancements in both large area processing and annealing of semiconductor surfaces. UV photons can either be applied via demagnifying a mask pattern image or by scanning a homogenized excimer beam across the substrate area. 193nm, 248nm and 308nm wavelength applications are supported.

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UV ultra-short laser pulse generation and amplification (UV 극초단 레이저 펄스의 발생과 증폭)

  • 이영우
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.324-326
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    • 2004
  • We have obtained ultra-short pulses with a wavelength of 616 nm from a Distributed Feedback Dye Laser pumped by excimer laser. Using the second harmonic generation, we obtained ultra-short pulse at 308nm in ultraviolet region and also performed amplification in 3 stages of XeCl amplifiers.

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Low-Loss Multimode Waveguides Using Organic-Inorganic Hybrid Materials

  • Yoon, Keun-Byoung
    • Macromolecular research
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    • v.12 no.3
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    • pp.290-292
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    • 2004
  • Multimode channel waveguides were fabricated using a direct UV patterning technology from thick films deposited by the one-step dip-coating of an organic/inorganic hybrid material (ORMOCER(equation omitted). The core size of the covered ridge waveguide was 43${\times}$51 $\mu\textrm{m}$$^2$; the waveguides can be readily prepared for multimode applications by direct UV patterning. The waveguides exhibited smooth surface profiles and a low optical loss of 0.07 ㏈/cm at the most important wavelength (850nm) used for optical interconnects.

Deterioration Mechanism of Paper according to Sizing and Beating(I)-Influences of Sizing- (사이징과 고해에 따른 종이의 열화기구(제1보)- 사이징의 영향 -)

  • 김봉용
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.30 no.2
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    • pp.24-29
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    • 1998
  • This study was carried out in order to elucidate the deterioration mechanism of paper according to various sizing chemicals. No additive paper and four kinds of papers containing rosin-alum, alum only, alkylketene dimer(AKD)-cation polymer and cation polymer only were treated by UV light to study changes of water-resistant, optical and mechanical properties from the view points of natural deterioration of paper. Since rosin chemicals have UV absorption at the relatively long wavelength region, rosins are degraded to form hydrophilic groups such as carboxylic acid from their double bonds by UV treatments. These phenomena caused the decreasing of sizing degree and wetting time in case of rosin-sized paper, while the UV treatments brought about the slight increase of wetting time in rosin-free papers such as no additive, alum and kymene only paper owing to the auto-sizing effect. Optical properties were primarily influenced by sizing chemicals. Rosin-sized paper showed lower brightness after UV and near UV treatment because of its UV instability.

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A highly integrable p-GaN MSM photodetector with GaN n-channel MISFET for UV image sensor system

  • Lee, Heon-Bok;Hahm, Sung-Ho
    • Journal of Sensor Science and Technology
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    • v.17 no.5
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    • pp.346-349
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    • 2008
  • A metal-semiconductor-metal (MSM) ultraviolet (UV) photodetector (PD) is proposed as an effective UV sensing device for integration with a GaN n-channel MISFET on auto-doped p-type GaN grown on a silicon substrate. Due to the high hole barrier of the metal-p-GaN contact, the dark current density of the fabricated MSM PD was less than $3\;nA/cm^2$ at a bias of up to 5 V. Meanwhile, the UV/visible rejection ratio was 400 and the cutoff wavelength of the spectral responsivity was 365 nm. However, the UV/visible ratio was limited by the sub-bandgap response, which was attributed to defectrelated deep traps in the p-GaN layer of the MSM PD. In conclusion, an MSM PD has a high process compatibility with the n-channel GaN Schottky barrier MISFET fabrication process and epitaxy on a silicon substrate.

Design and Analysis of Flame Signal Detection with the Combination of UV/IR Sensors (UV/IR센서 결합에 의한 불꽃 영상검출의 설계 및 분석)

  • Kang, Daeseok;Kim, Eunchong;Moon, Piljae;Sin, Wonho;Kang, Min-goo
    • Journal of Internet Computing and Services
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    • v.14 no.2
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    • pp.45-51
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    • 2013
  • In this paper, the combination of ultraviolet and infrared sensors based design for flame signal detection algorithms was proposed with the application of light-wavelength from burning. And, the performance result of image detection was compared by an ultraviolet sensor, an infrared sensor, and the proposed dual-mode sensors(combination of ultraviolet and infrared sensors).

Accumulation of Chlorogenic Acid as a near UV-shielding Compound in Cauliflower Grown under Enhanced UV-B Radiation

  • Shibata, Hitoshi;Tanaka, Tomoyuki;Yonemura, Takeshi;Sawa, Yoshihiro;Ishikawa, Takahiro
    • Journal of Photoscience
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    • v.9 no.2
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    • pp.436-438
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    • 2002
  • Since solar radiation contains wavelength essential for photosynthesis accompanying with near-UV light, UV-B effects on biological parameters and acclimation mechanisms are influenced by photosynthetically active radiation (PAR). Therefore, to elucidate near-UV shielding mechanism in higher plants, we cultivated cauliflower under usual solar radiation and increased UV-B from fluorescent lamps, two- or three-fold excess over continuously estimated UV-B dose in PAR during daytime, using computer regulated systems. Increased UV-B radiation had little effect on growth expressed as fresh weigh and leaf area. Water soluble low molecular weight compounds showing absorption in near UV region were enhanced according to the irradiated UV-B dose. One of compounds in cauliflower leaves was identified as chlorogenic acid. This was found to have no near-UV photosenSitizerable activity and is known to have an ability to scavenge a wide species of active oxygen. Another pro-oxidant compound that generates superoxide anion radical under near-UV irradiation was not induced by increased UV-B during cultivation, and identified as lumazine, a degradation product from folic acid.

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Wavelength Conversion Lanthanide(III)-cored Complex for Highly Efficient Dye-sensitized Solar Cells

  • Oh, Jung-Hwan;Song, Hae-Min;Eom, Yu-Kyung;Ryu, Jung-Ho;Ju, Myung-Jong;Kim, Hwan-Kyu
    • Bulletin of the Korean Chemical Society
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    • v.32 no.8
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    • pp.2743-2750
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    • 2011
  • Lanthanide(III)-cored complex as a wavelength conversion material has been successfully designed and synthesized for highly efficient dye-sensitized solar cells, for the first time, since light with a short wavelength has not been effectively used for generating electric power owing to the limited absorption of these DSSCs in the UV region. A black dye (BD) was chosen and used as a sensitizer, because BD has a relatively weak light absorption at shorter wavelengths. The overall conversion efficiency of the BD/WCM device was remarkably increased, even with the relatively small amount of WCM added to the device. The enhancement in $V_{oc}$ by WCM, like DCA, could be correlated with the suppression of electron recombination between the injected electrons and $I_3{^-}$ ions. Furthermore, the short-circuit current density was significantly increased by WCM with a strong UV light-harvesting effect. The energy transfer from the Eu(III)-cored complex to the $TiO_2$ film occurred via the dye, so the number of electrons injected into the $TiO_2$ surface increased, i.e., the short-circuit current density was increased. As a result, BD/WCM-sensitized solar cells exhibit superior device performance with the enhanced conversion efficiency by a factor of 1.22 under AM 1.5 sunlight: The photovoltaic performance of the BD/WCM-based DSSC exhibited remarkably high values, $J_{sc}$ of 17.72 mA/$cm^2$, $V_{oc}$ of 720 mV, and a conversion efficiency of 9.28% at 100 mW $cm^{-2}$, compared to a standard DSSC with $J_{sc}$ of 15.53 mA/$cm^2$, $V_{oc}$ of 689 mV, and a conversion efficiency of 7.58% at 100 mW $cm^{-2}$. Therefore, the Eu(III)-cored complex is a promising candidate as a new wavelength conversion coadsorbent for highly efficient dye-sensitized solar cells to improve UV light harvesting through energy transfer processes. The abstract should be a single paragraph which summaries the content of the article.

Effects of Enhanced Ultraviolet-B Radiation on Plants (오존층 파괴에 의한 자외선 증가가 식물에 미치는 영향)

  • Hak Yoon Kim;Moon Soo Cho
    • Protected Horticulture and Plant Factory
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    • v.10 no.3
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    • pp.197-206
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    • 2001
  • The depletion of stratospheric ozone is regarded as a major environmental threat to plant growth and ecosystem. The ozone depletion has caused plants to be exposed to an increased penetration of solar ultraviolet-B (UV-B) radiation in the 280-320 nm wavelength range. Enhanced UV-B radiation may have influence on plants biological functions in many aspects including inhibition of photosynthesis, DNA damage, lipid peroxidation, changes in morphology, phenology, and biomass accumulation. To cope with the damage by UV radiation, plants have evolved to have protective mechanisms, such as photorepair, accumulation of UV-absorbing compounds, leaf thickening and activation of antioxidative enzymes. The objective of this review is to address the effects of enhanced UV-B on plant growth, UV-B action mechanisms and protection and protection mechanisms in plants.

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