• Journal of Korean Society of Water and Wastewater
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• v.26 no.4
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• pp.521-533
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• 2012

Interest in application of ultraviolet light technology for primary disinfection that used for the treatment of water for consumption and wastewater has increased significantly in recent years. Analysis of these systems has been carried out using Computational Fluid Dynamics (CFD) procedure. It offers advantages over other techniques in specific circumstances. CFD has emerged as a powerful tool to aid design of a UV reactor by providing the UV dose delivered by the proposed reactor design and allowing engineers to evaluate alternative designs in much less time and at a reasonable cost. In this study, five different configurations of the apparatus depending on the location of the exit are evaluated in terms of maximum dose, minimum dose, flow patterns, particle tracks and transient dose. The configuration 3 results have higher minimum UV dose value and uniform particle distribution of the UV dose on the outlet than other's.

• Molecules and Cells
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• v.21 no.2
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• pp.218-223
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• 2006

The effect of poly(ADP-ribosyl)ation on the stability of p53 in SK-HEP1 cells treated with UV light was examined. Intracellular levels of p53 increased in cells treated with a low dose of UV light ($20J/m^2$), whereas they increased but then declined after a higher dose of UV ($100J/m^2$). Intracellular levels of p53 in the UV treated SK-HEP1 cells were dependent on the UV dose. Use of proteasome inhibitors revealed that p53 is degraded by proteasomal proteolysis after high doses of UV light. We present evidence that, at low doses, poly(ADP-ribose)polymerase (PARP) poly(ADP-ribosyl) ates p53 and protects it from proteasomal degradation before caspase-3 is activated, whereas at high doses the cells undergo UV induced apoptosis and PARP is cleaved by caspase-3 before it can protect p53 from degradation. Destabilization of p53 by cleavage of PARP may be important in cell fate decision favoring apoptosis.

• Journal of Photoscience
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• v.6 no.1
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• pp.1-3
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• 1999

Solar ultraviolet-A (UV-A) irradiances indicent on a horizontal surface at Taegu of Korea during 1995-1998 were calculated with 5 min averages of measurements taken every 30 seconds by a broadband UV- A sensor. The maximum and minimum of monthly averages of daily UV-A dose were 499.37 KJ m-2 day-1 inJuly and 171.09 KJ m--2 day-1 in December for 4 years of the observation period. The maxima of daily UV-A dose and instandaneous UV-A were observed as 846.46KJ m-2 day-1 June 7, 1998 and 37.22 W m-2 at 12 : 15, July 16, 1998, respectively. Increasing trends in annual maxima of daily UV-A dose and instantaneous UV-A were averaged to 6.4% and 6.7% , respectively, per year during 1995-1998 at Taegu, Korea.

• Journal of Korean Society on Water Environment
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• v.23 no.2
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• pp.274-280
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• 2007

The photochemical decolorization of Rhodamine B (RhB) in water has been carried out by photo-Fenton process. The effect of applied $H_2O_2$, $Fe^{2+}$ dose, solution pH and UV dose have been studied. The influence of constituent processes of photo-Fenton such as UV, $H_2O_2$ and Fenton has been investigated. Comparison of RhB removal was made between the photo-Fenton and $UV/H_2O_2$ process. The results obtained showed that the optimum dosage of $Fe^{2+}$ and $H_2O_2$ were 0.0031 mmol and 0.625 mol, respectively. pH 3 is found to be the optimum pH of for photo-Fenton process. pH and UV dose strongly influenced the decolorization of RhB in photo-Fenton process. The photo-Fenton and $UV/H_2O_2$ processes showed similar decolorization and seem to be appropriate for the decolorization of dye wastewater.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.7
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• pp.94-106
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• 2003

A pilot study was performed to examine the feasibility of UV disinfection system and the reactivation of indicator microorganisms (TC, FC, E. coli) after UV irradiation for agricultural reuse of reclaimed water. Photoreactivation and dark repair enable UV-inactivated microorganisms to recover and may reduce the efficacy of UV inactivation, which might be drawbacks of the UV disinfection method. The effluent of biofilter for 16-unit apartment house was used as input to the UV disinfection system, and average SS and BOD concentration were 3.8 and 5.7 mg/L, respectively, and the mean level of total coliform was in the range of $1.0\times10^4$ MPN/100mL. UV disinfection was found to be effective and it reduced mean concentration of indicator microorganisms (total coliform, fecal coliform, and E. coli) to less than 100 MPN/100mL within 60s exposure using 17, 25, and 40W lamps. Two UV doses of 6 and 16 mW$\cdot$s/$\textrm{km}^2$ were applied and microorganisms reactivation was monitored under the dark, photoreactivating light, and solar irradiation. Microorganisms reactivation was observed in the UV dose of 6 mW$\cdot$s/$\textrm{km}^2$, and numbers increased up to 5% at the photoreactivating light and 1% at the dark. However, microorganisms were inactivated rather than reactivated at the solar radiation and numbers decreased to non-detectible level about below 2 MPN/100mL in 4 hours. In the case of 16 mW$\cdot$s/$\textrm{km}^2$, microorganism reactivation was not observed indicating that UV dose might affect the reactivation process such as photoreactivation and dark repair. Therefore, concerns associated with microorganism reactivation could be controlled by sufficient UV dose application. Agricultural reuse of reclaimed water might be even less concerned due to exposure to the solar irradiation that could further inactivate microorganisms. The pilot study result is encouraging, however, sanitary concern in water reuse is so critical that more comprehensive investigation is recommended.

• 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.

• YAKHAK HOEJI
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• v.36 no.5
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• pp.449-454
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• 1992

The effect of radioprotective ginseng protein fraction on DNA repair capacity was determined by measuring the amount of $^{3}H-thymidine$ incorporated into DNA in the process of repair synthesis for UV damaged DNA. CHO-Kl cells were prepared whose semiconservative replication was inhibited by trimethylpsoralen plus near-UV(PUVA) treatment. When the cells were exposed to UV light alone, the DNA repair capacity was increased at first and then decreased as UV dose increased. However, when the ginseng fraction was treated to the cells, the DNA repair capacity was kept increasing regardless of UV dose increment. When the concentration of protein contained in the added fraction was increased gradually, the repair capacity was also increased almost linearly showing dose-response relationship of the effect. These results suggest that the enhancement of DNA repair capacity of the cell can be one of the mechanisms of radioprotection by the ginseng fraction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.3822-3826
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• 2012

We have studied the effect of temperature and exposure time on the UV curing rate of Urethane Acrylate. UV dose has been modulated by changing the electric power, and temperature has been controled by coating rate and water temperature of the coating roll. Curing rate was evaluated by measuring gel fraction of the cured film. It has been found that effect of coating velocity on the gel fraction of the final film is predominant, but role of temperature of the UV chamber is negligible. These observations imply that exposure time of UV light is critical to have a fully cured film. To better understand the effect of design and operating condition of UV coater on the behavior of UV curing of Urethane Acrylate, we have also conducted heat-flux analysis of UV chamber.

• Journal of Korean Society on Water Environment
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• v.20 no.2
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• pp.145-150
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• 2004

This study investigated the effect of chlorine dose and chlorine reaction time for the formation of haloacetic acids (HAAs). According to the results, HAA formation was highly affected by chlorine dose and chlorine reaction time. HAA formation reached a plateau value at 30 mg/L of chlorine dose and 24 hr of chlorine reaction time. For the speciation of formed HAAs in the test water, the concentration of brominated-HAAs was significantly lower than that of chlorinated-HAAs because of low level of bromide ion concentration in the test water. It also investigated the removal efficiency of HAA precursors by several unit processes, such as ozone alone, UV alone, and combined ozone/UV system. Of them, ozone/UV system was proved as the best process to control the HAAs formation. The increase of the brominated-HAAs was observed during ozonation with and without UV irradiation showing the slight increase of total HAA concentrations.

• The Korean Journal of Ecology
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• v.24 no.2
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• pp.117-119
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• 2001

Solar ultraviolet-B (UV-B) irradiances incident on a horizontal surface at Taegu, Korea during 1996-1998 were calculated with 5 minute averages of measurements taken every 30 seconds by a broadband UV-B sensor. The average, maximum and minimum of daily UV-B dose were 11.31, 22.04 and 3.20kJ m$^{-2}$ day$^{-1}$ , respectively, for the measuring period. Variations in stratospheric ozone concentration measured from space explain 85% of changes in the daily UV-B dose. It was expected that decrease of 50 Du in stratospheric ozone cause increase of 24.1% in daily UV-B dose in this study.