• Title, Summary, Keyword: UV wavelength

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The Study of Thermal Effect Suppression and Wavelength Dependence of Azobenzene-coated FBG for UV Sensing Application (UV광 측정용 아조벤젠 코팅된 FBG의 열적 효과 제거 및 파장 의존성에 대한 연구)

  • Choi, Dong-Seok;Kim, Hyun-Kyoung;Ahn, Tae-Jung
    • Korean Journal of Optics and Photonics
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    • v.22 no.2
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    • pp.67-71
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    • 2011
  • In the paper, we have demonstrated an azobenzene-coated fiber Bragg grating (FBG) for monitoring ultraviolet light (UV) intensity in remote measurement. The elasticity of the coated azobenzene polymer is changed by the UV light, which induces a center wavelength change corresponding to the change of the FBG's grating period. The wavelength shift resulting from both UV light and other light with the wavelength out of the UV range was about 0.18 nm. In order to improve the accuracy of the measurement, the center wavelength shift caused by radiant heat of the light source was sufficiently removed by using a thermal filter. The amount of the center wavelength shift was consequently reduced to 0.06 nm, compared to the result without the thermal filter. Also, the FBGs coated by using azobenzene polymer were produced by two different methods; thermal casting and UV curing. Considering temperature dependence, UV curing is more suitable than thermal casting in UV sensor application of the azobenzene-coated FBG. In addition, we have confirmed the wavelength dependence of the optical sensor by means of four different band pass filters. Thus, we found out that the center wavelength shift per unit intensity is 0.029 [arb. unit] as a maximum value at 370 nm wavelength region and that the absorption spectrum of the azobenzene polymer was very consistent with the wavelength dependence of the azobenzene-coated FBG.

Analysis of Disinfection Performance of UV LEDs for a Phytoplankton (식물성 플랑크톤에 대한 UV LED의 살균성능 분석)

  • Kil, Gyung-Suk;Choi, Sung-Kuk;Park, Dae-Won;Kim, Sung-Wook;Cheon, Sang-Gyu
    • Journal of the Korean Society of Marine Engineering
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    • v.33 no.6
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    • pp.959-964
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    • 2009
  • This paper dealt with the disinfection performance by Ultra-Violet Light Emitting Diode (UV LED) for a phytoplankton as a basic study for the development of a low-energy consumption ballast water treatment system. UV LEDs having peak wavelength of 255nm, 265nm and 280nm were used in the experiment. UV LED modules with driving circuit were fabricated, and optical and electrical characteristics of them were analyzed. The disinfection performance for phytoplankton depending on the UV wavelength was evaluated by comparing the number of phytoplankton before and after the UV treatments. The experimental result showed that the highest disinfection wavelength for the phytoplankton was 265nm.

Dippy Time Dependence of Transmittance Edge and Half Point in the UV cut lens' manufacture (UV 차단렌즈의 제작에서 광 투과율 Edge 및 Half Point의 Dippy 시간의존성)

  • Kim, Yong-Geun
    • Journal of Korean Ophthalmic Optics Society
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    • v.6 no.1
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    • pp.101-105
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    • 2001
  • It was measured the transmittance and the reflectance by tie dip method using the UV cut lens' UV solution. The half point and the edge wavelength of the transmittance were wry well applied to the eqution of a dip time dependence. $$W=W_0+A_1{e}{x}{p}[-(x-x_1)/t_1]$$ The half point wavelength of the transmittance shifted from 358 nm to 408 nm and the edge wavelength moved from 340 nm to 398 nm. The more dip time had long the less intensity of main reflectance peak-380 nm was small and shifted to long wavelength regions. And the component peak of UV solution began to show in dip time-10 min.

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Effects of organic carbon and UV wavelength on the formation of dissolved gaseous mercury in water under a controlled environment

  • Lee, Jae-In;Yang, Ji-Hye;Kim, Pyung-Rae;Han, Young-Ji
    • Environmental Engineering Research
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    • v.24 no.1
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    • pp.54-62
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    • 2019
  • The effects of UV wavelength and dissolved organic carbon (DOC) on the formation of dissolved gaseous mercury (DGM) were investigated in a controlled environment. To remove any other influences than UV wavelength and DOC, purified water was used as the working solution. DGM was instantly produced with irradiation of all UV lights even without DOC; whereas, there was no noticeable increase of DGM during irradiation of visible light. The amount of formed DGM increased as the DOC concentration increased even in dark conditions; however, UV-B irradiation significantly promoted DGM production with DOC present. The rate constants of reduction ranged from $1.4{\times}10^{-6}s^{-1}$ to $3.5{\times}10^{-5}s^{-1}$, with the lower values occurring under the dark condition without DOC and the higher values resulting under UV-B irradiation and high DOC concentration. However, DGM production was not linearly correlated with the DOC concentration at higher range of DOC in this study. Future studies should investigate the effects of DOC concentration on mercury (Hg) reduction over the broad range of DOC concentrations with different DOC structures and with other influencing parameters.

PLC-Type WDM directional coupler and the effect of wavelength shift by UV irradiation (PLC형 WDM 방향성 결합기와 UV 조사에 의한 파장 천이 효과)

  • 한상필;박태상;최영복;강민정;김상인;박수진;정기태
    • Korean Journal of Optics and Photonics
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    • v.11 no.1
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    • pp.33-36
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    • 2000
  • KrF excimer laser, which is useful for fabrication of fiber gratings, was irradiated on the PLC-type WDM directional coupler and the transmission wavelength shift was observed as a function of UV exposure time. The effective refractive index change of rectangular silica waveguide was calculated from the wavelength shift measurement and the coupled mode theory. heory.

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Estimation of Application of Artificially Deteriorated Silk by Ultraviolets for Conservation of Paintings on the Silk (견본 회화보존처리에 자외선 인공열화견의 적용성 평가)

  • Oh, Joon-Suk;Chun, Ji-Youn;Lim, In-Kyung
    • Journal of Conservation Science
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    • v.27 no.2
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    • pp.191-199
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    • 2011
  • A study was done to compare the properties of artificially deteriorated silk with ultraviolets for reinforcing of loss area of paintings on silk. Deteriorated surface of raw silk irradiated by long-wavelength ultraviolet(UV-A) than short-wavelength ultraviolet(UV-C) was similar to naturally aged raw silk. UV-A irradiation raw silk was slowly decreased in tensile tenacity and elongation and lowered in yellowness index than that of UV-C. Water content of UV-A irradiation raw silk than that of UV-C was higher. UV-A irradiation raw silk had no problem in dyeing and inpainting for conservation because of low yellowness index. UV-C irradiation raw silk was brittle, but UV-A irradiation raw silk was seemed to tough and similar to naturally aged raw silk. Korean painting conservator estimated that UV-A irradiation raw silk was more proper for reinforcing of loss area of paintings on silk than that of UV-C.

Characteristics of Disinfection and Removal of 2-MIB Using Pulse UV Lamp (펄스 UV 램프를 이용한 미생물 소독 및 2-MIB 제거 특성)

  • Ahn, Young-Seog;Yang, Dong-Jin;Chae, Seon-Ha;Lim, Jae-Lim;Lee, Kyung-Hyuk
    • Journal of Korean Society of Water and Wastewater
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    • v.23 no.1
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    • pp.69-75
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    • 2009
  • The characteristics of disinfection and organic removal were investigated with pulse UV lamp in this study. The intensity and emission wavelength of pulse UV Lamp were compared with low pressure UV lamp. The emission spectrum range of pulse UV lamp was between 200 and 400 nm while the emission spectrum of low pressure UV lamp was only single wavelength of 254nm. 3 Log inactivation rate of B. subtilis spore by pulse UV and low pressure UV irradiation was determined as $44.71mJ/cm^2$ and $57.7mJ/cm^2$, respectively. This results implied that wide range of emission spectrum is more effective compared to single wavelength emission at 254nm. 500ng/L of initial 2-MIB concentration was investigated on the removal efficiency by UV only and $UV/H_2O_2$ process. The removal efficiency of UV only process achieved approximately 80% at $8,600mJ/cm^2$ dose. 2-MIB removal rate of $UV/H_2O_2$ (5 mg/L $H_2O_2$) process was 25 times increased compared to UV only process. DOC removal efficiency for the water treatment plant effluent was examined. The removal efficiency of DOC by UV and $UV/H_2O_2$ was no more than 20%. Removal efficiency of THMFP(Trihalomethane Formation Potential), one of the chlorination disinfection by-products, is determined on the UV irradiation and $UV/H_2O_2$ process. Maximum removal efficiency of THMFP was approximately 23%. This result indicates that more stable chemical structures of NOM(Natural Organic Matter) than low molecule compounds such as 2-MIB, hydrogen peroxide and other pollutants affect low removal efficiency for UV photolysis. Consequently, pulse UV lamp is more efficient compared to low pressure lamp in terms of disinfection due to it's broad wavelength emission of UV. Additional effect of pulse UV is to take place the reactions of both direct photolysis to remove micro organics and disinfection simultaneously. It is also expected that hydrogen peroxide enable to enhance the oxidation efficiency on the pulse UV irradiation due to formation of OH radical.

Ultraviolet Light Sensor Based on an Azobenzene-polymer-capped Optical-fiber End

  • Cho, Hee-Taek;Seo, Gyeong-Seo;Lim, Ok-Rak;Shin, Woojin;Jang, Hee-Jin;Ahn, Tae-Jung
    • Current Optics and Photonics
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    • v.2 no.4
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    • pp.303-307
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    • 2018
  • We propose a simple ultraviolet (UV) sensor consisting of a conventional single-mode optical fiber capped with an azobenzene-moiety-containing polymer. The UV light changes the dimensions of the azobenzene polymer, as well as the refractive index of the material. Incident light with a wavelength of 1550 nm was reflected at the fiber/polymer and polymer/air interfaces, and interference of the reflected beams resulted in spectral interference that shifted the wavelength by 0.78 nm at a UV input power of $2.5mW/cm^2$. The UV sensor's response to wavelength is nonlinear and stable. The response speed of the sensor is limited by detection noise, which can be improved by modifying the insertion loss of the UV sensor and the signal-to-noise ratio of the detection system. The proposed compact UV sensor is easy to fabricate, is not susceptible to electromagnetic interference, and only reacts to UV light.

Sensitivity Analysis by Using Global Imager for Retrieval of Biomass Burning Aerosols

  • Lee, Hyun-Jin;Kim, Jae-Hwan
    • Asian Journal of Atmospheric Environment
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    • v.5 no.2
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    • pp.79-85
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    • 2011
  • The purpose of this study is to evaluate the strength of the near-UV wavelength of 380 nm relative to visible and near-IR bands, and to find the suitable wavelength for detecting aerosols by using the Global Imager (GLI) sensor aboard the Advanced Earth Observing Satellite-II (ADEOS-II). Sensitivity analysis is performed for the retrieval of biomass burning aerosols by employing the radiative transfer model Rstar5b. It is determined that background surface reflectance in the blue band is similar to that in the near-UV band, and that wavelengths in the blue bands are more sensitive to the Aerosol Optical Thickness (AOT) than wavelengths in the near-UV band. The Total Ozone Mapping Spectrometer (TOMS) Aerosol Index (AI) is used in the indirect method used for aerosol retrieval, and the wavelength pair 380 nm and 460 nm is determined to be the most sensitive to the AOT. The results of this study suggest that wavelengths in the blue bands are suitable for detecting biomass burning aerosols over the Korean peninsula.

A study on the curing characteristics of multi-concentrating UV-LED Curable Coating (다중 집광성 UV-LED 경화형 코팅의 경화특성에 관한 연구)

  • Jung, Chan-Gwon;Kim, Beom-Su;Park, Dae-Hee
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.10
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    • pp.339-345
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    • 2018
  • We investigated the curing properties of cured coatings for a multi-focal UV-LED. The coatings are for LEDs that operate at multiple UV wavelengths, unlike conventional single-wavelength UV-LEDs. Using UV-LED light sources with wavelengths of 365, 395, 420, and 450 nm, we analyzed the optical characteristics such as the direction of light flux and light source. We also analyzed the curing characteristics at each UV-LED wavelength to optimize the LED for composite wavelengths. The curing performance state was predicted through computer simulation for when the multiple wavelengths of UV light sources are superimposed, and then actual LEDs were designed and fabricated. To improve the internal high-speed curing, a multi-spot module was fabricated, in which each LED is condensed, and multiple wavelengths are synthesized and condensed at the same position. The adhesive strength, surface hardness, and internal hardness of the curing agent were tested by varying the wavelength combination conditions. The surface hardening and internal hardening were compared and analyzed using a hardness tester and FT-IR analyzer. As a result, the characteristics of the surface and internal hardness were improved by a multi-spot method in which four wavelengths were overlapped in a UV-LED rather than a single wavelength.