• Title/Summary/Keyword: UV intensity model

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A Study on the UV Intensity Models and their Affecting Factors (자외선 강도 산정 모델과 영향 인자에 관한 연구)

  • Kim, Dooil;Choi, Younggyun;Kim, Sunghong
    • Journal of Korean Society of Water and Wastewater
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    • v.22 no.4
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    • pp.421-427
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    • 2008
  • UV disinfection is widely used in water treatment facilities and wastewater treatment plant because of its effectiveness to removal of pathogen and Giardia which is resistant to traditional chemical disinfection. As a design and performance tool of UV disinfection system, 3 dimensional UV intensity models were composed and simulated to compare each other and to find affecting factors in this study. Reflection, refraction and absorption are important parameters in UV intensity model and MPSS and MSSS model can reflect these parameters while LSI model can not. Absorption is the most important parameters among the reflection, refraction, absorption and shadowing so, this should not be neglect. Based on this simulation, shadowing effect is negligible when the number of installed lamp is a few but, this effect can not be neglectable when the number of installed lamp is quite a few. The errors according to shadowing effect is increased as the number of lamp installed increased.

Development of an UV Distribution Model for the Design of a Submerged UV Disinfection Reactor and Its Application (침지형 자외선 살균조 설계를 위한 자외선 분포 모델의 개발 및 적용)

  • Park, Changyeun;Kim, Sunghong;Choi, Younggyun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.41 no.5
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    • pp.505-512
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    • 2021
  • A 3D model was developed to calculate the UV intensity of a submerged-type UV disinfection reactor. Numerical experiments were conducted by inputting the design factors of an open channel-type disinfection reactor and a pipe-type disinfection reactor that were installed in an actual sewage treatment plant. The following data were obtained: The average UV intensity of the installed open channel-type reactor and pipe-type reactor was 7.87 mW/cm2 and 13.09 mW/cm2, respectively; the UV dose reflecting the UV irradiation time and taking into account attenuation effects such as mixing imbalance, lamp aging, temperature, and fouling, was expected to be 21.1 mJ/cm2 and 24.8 mJ/cm2, respectively, and these values are 5 % and 24 % higher than the target UV dose of 20 mJ/cm2, respectively. By using the UV3D model, the optimal lamp position, which maximizes the average UV intensity without changing the size of the disinfection reactor or lamp output power, can be found. In this case, by only adjusting the lamp position, the average UV intensity can be increased by 0.9 % for the open channel-type and 0.5 % for the pipe-type, respectively. A better average UV intensity can be obtained by model simulation. By adjusting the horizontal and vertical ratio of the open channel-type reactor and by moving the lamp position, the average UV intensity can be increased by 7.4 % more than the present case.

Optical characteristics of the UV intensity distribution in a non-contact type UV photoreactor (비접촉식 자외선 반응조에서 자외선 강도 분포의 광학적 특성)

  • Jeon, Hwa-Bong;Yun, Jung-Won;Kim, Sung-Hong
    • Journal of Korean Society of Water and Wastewater
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    • v.26 no.2
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    • pp.257-264
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    • 2012
  • The concept of a non-contact type of UV disinfection system was introduced in this study. UV lamps and their quartz sleeves hang over the water surface and there is no interface between the sleeve and water. Obviously, there is no fouling. Based on optical laws and other UV distribution models, a detail mathematical model for a non-contact type UV disinfection system was developed in this study. Pathway length of UV light in a non-contact type photoreactor is longer than that in a submerged type photoreactor because the light is more refractive while passing through 3 interfaces of medium. But the pathway length passing through the water media is not significantly longer than that in a submerged type photoreactor so, the absorption of UV light by water is not significantly different from the other system. Due to the reflection effect, UV intensity is rapidly decreased as the horizontal distance from the light source is increased. The reflective attenuation in a non-contact type photoreactor is higher than that in a submerged type photoreactor. These mean that the short photoreactor is advantageous than the narrow-long photoreactor for the non-contact type photoreactor in an optical point of view.

Kinetic analysis of E. coli disinfection using UV-LED (LED 광원 UV에 의한 대장균(E. coli) 소독의 속도론 해석)

  • Kim, Kyeong-Rae;Chang, In-Soung
    • Journal of Korean Society of Water and Wastewater
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    • v.35 no.6
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    • pp.489-496
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    • 2021
  • Water disinfection using UV-LED(Light emitting diode) has many advantages, such as smaller footprint and power consumption as well as relatively longer lifespan than those of conventional mercury-UV lamps. Moreover, UV-LED disinfection is considered an environmentally benign process due to its mercury-free nature. In this study, disinfection using an LED module emitting 275nm UV was carried out. 384 UV-LEDs were put into a cylinder tube with a capacity of 1.7 liters. The UV intensity of the UV-LED module was controlled from 1.7 to 8.4 mW/cm2. The disinfection efficiency for the model microorganism solutions(E. coli ) was monitored. As the UV intensity(I) and contact time(t) varied, inactivation of the microorganisms from 2 to 4-log-removals(i.e., 99 to 99.99% of disinfection efficiency) was achieved. Disinfection using UV-LED was followed to 1st order reaction and the reaction rate constant, k was determined. In addition, the relationship between UV intensity(I) and contact time(t) in order to obtain 99.99% of disinfection efficiency was modeled: I1.2·t= 460, which indicates that the product of UV intensity and contact time requiring 4-log-removals is always constant.

The Study of Statistical Optimization of NDMA Treatment using UV-Process (UV공정을 이용한 NDMA처리 통계적 최적화 연구)

  • Song, Won-Yong;Chang, Soon-Woong
    • Journal of Korean Society on Water Environment
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    • v.25 no.1
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    • pp.96-101
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    • 2009
  • The aim of this research was to apply experimental design methodology to optimizetion the photolytic degradation of N-nitrosodimethylamine (NDMA). Reactions were mathematically described as a function of parameters such as pH, initial NDMA concentration, and UV intensity using the Box-Behnken method. The results showed that the responses of NDMA removal (%) in photolysis were significantly affected by the synergistic effect of linear term of pH, initial NDMA concentration and UV intensity. The application of Response Surfase Methodology (RSM) using the Box-Behnken method yielded the following regression equation, which is an empirical relationship between the removal (%) of NDMA and test variables in coded unit: Y = 50.929 + 16.073(UV) - 7.909(NDMA) - 27.432(pH) - 11.385(UV)(NDMA) - 7.363(UV)(pH) +13.811(NDMA)(pH). The model predictions agreed well with the experimentally observed result ($R_2(ad.)=89%$).

Improvement of a UV/Ozone Duplex Sterilizer (UV/Ozone 복합 살균기의 살균력 개선 연구)

  • Jee, Jung-Eun;Yang, Won-Kyun;Park, Eun-Chul;Kim, Kang-Suk;Joo, Jung-Hoon
    • Journal of the Korean institute of surface engineering
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    • v.41 no.2
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    • pp.76-82
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    • 2008
  • We investigated sterilization characteristics of UV lights by counting the number of bacteria units with varying sterilization time and distance from the light source. We focused on an idea that UV light of 184.9 nm could generate ozone and developed a new sterilizer. The UV-ozone duplex system sterilized bacteria faster than UV-only sterilizers. To reduce shadowing effects by target objects, we used UV transparent quartz plate as a support and put a reflecting plate. Distribution of UV irradiation intensity and ozone supply were analyzed by a 3D model and measured by a semiconductor UV sensor. But even with an Al reflector, multi-layered pens could not be treated properly from UV irradiation only. Ozone generating lamp could treat more uniformly multi-layered pens with a stirring fan by supplying ozone to shadowed surfaces.

MODEL CALCULATIONS OF THE UV - EXCITED MOLECULAR HYDROGEN IN INTERSTELLAR CLOUDS

  • Lee, Dae-Hee;Pak, Soo-Jong;Seon, Kwang-Il
    • Publications of The Korean Astronomical Society
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    • v.20 no.1 s.24
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    • pp.7-10
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    • 2005
  • We have calculated 2448 interstellar cloud models to investigate the formation and destruction of high rotational level $H_2$ according to the combinations of five physical conditions: the input UV intensity, the $H_2$ column density, cloud temperature, total density, and the $H_2$ formation rate efficiency. The models include the populations of all the accessible states of $H_2$ with the rotational quantum number J < 16 as a function of depth through the model clouds, and assume that the abundance of $H_2$ is in a steady state governed primarily by the rate of formation on the grain surfaces and the rates of destruction by spontaneous fluorescent dissociation following absorption in the Lyman and Werner band systems. The high rotational levels J = 4 and J = 5 are both populated by direct formation into these levels of newly created molecules, and by pumping from J = 0 and J = 1, respectively The model results show that the high rotational level ratio N(4)/N(0) is proportional to the incident UV intensity, and is inversely proportional to the $H_2$ molecular fraction, as predicted in theory.

The Fluorescent Effects on the N-Substituents of Polyarylenevinylenes Having 1,2-Diphenylmaleimide Moieties

  • Lee, Jun-Kyu;Yang, Nam-Choul;Park, Ho-Wook;Suh, Dong-Hack
    • Macromolecular Research
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    • v.11 no.2
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    • pp.92-97
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    • 2003
  • Model compounds and polymers having N-substituted 1,2-diphenylmaleimide moieties were synthesized and characterized by NMR, IR, UV, and fluorescence spectroscopy. The fluorescence intensity could be controlled by N-substituents of model compounds and polymers. As the structure of an N-substituent of them was bulkier, or the electron density of an N-substituent was denser, the photoluminescence intensity was increased. All the compounds showed greenish yellow photoluminescence with the maximum intensity between 510 and 537 nm. From quantum efficiency data of the model compounds and the polymers, the fluorescence intensity of the polymer 11 was higher than that of the model compound 4.

A Study on Optimal Design of UV Contactor using an Optical Radiation Model (광학모델을 이용한 자외선 접촉조 최적 설계에 관한 연구)

  • Choi, Younggyun;Kim, Dooil;Kim, Sunghong
    • Journal of Korean Society on Water Environment
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    • v.25 no.4
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    • pp.547-552
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    • 2009
  • Because of refractory property of light, the travel path of UV light becomes longer than the straight line and shorter solely in water as UV light passes sequentially through air, quartz and water. Note that water significantly absorbs UV light. Hence, UV intensity shall be estimated to be lower when refraction is neglected than it is considered. Reflection is also critical for the design of UV radiation system. While the reflection at the interface of air and quartz is low enough to ignore, it is too high to be ignored at the interface of quartz and water. Assuming constant power, smaller length to width ratio of UV reactor is beneficial and single-lamp system is preferred to multi-lamps. Under the given cross section, optimal lamp positions could be decided. For example of an elliptical reactor with dual lamps, the optimal lamp locations shall be the 1/3 and 2/3 position of the longer axis.

Analysis of the shrinkage and warpage of Wafer lens during UV curing (Lens 성형시 UV경화 반응에 따른 수축 및 변형 대한 해석적 접근)

  • Park, Sihwan;Moon, Jong-Sin
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.11
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    • pp.6464-6471
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    • 2014
  • The UV curing method is a popular process for lens molding on a unit wafer. This process, however, has several drawbacks including wafer adhesion during the ejection process after curing, errors in lens shape and wafer warpage due to material shrinkage during the curing process, and lens centering errors on both sides of a wafer. Among these, the lens shape error and warpage are influenced directly by the UV curing process due to factors including the UV radiation uniformity, the degree of cure according to UV intensity, and the shrinkage characteristics of the material. Therefore, a theory is needed not only to understand the change in the material characteristics, such as the shrinkage rate due to the curing reaction, but also to establish a model. In addition, an analysis system is needed to realize the model. This study proposes a new analysis method for the wafer lens molding process by Comsol modeling. This method was verified by comparing the results with those of the actual process.