• Clean Technology
• /
• v.4 no.1
• /
• pp.35-44
• /
• 1998

Photodecomposition behaviors of volatile organic compounds (VOCs ; benzene, toluene, ethylbenzene and xylenes) over UV irradiation and UV irradiation with $TiO_2$ powder catalyst were studied and the extent of degradation were also investigated under various reaction conditions. The reactions were conducted in a quartz annular reactor equipped with a medium pressure mercury lamp. As a result, the extents of degradation were 92% for toluene and ethylbenzene, 83% for benzene, and 82% for xylenes under UV irradiation. And they were 92% for toluene, 82% for xylene and ethylbenzene, and 53% for benzene under UV irradiation with $TiO_2$ powder. Analyses of reacted samples by FID-gas chromatograph with Purge & Trap concentrator and GC-MS indicated that the aromatics formed many intermediates.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.12
• /
• pp.2310-2316
• /
• 2016

We studied the effect of $Co^{60}$ gamma-radiation on the fiber Bragg gratings (FBGs) by irradiation time of UV Krypton fluoride (KrF) excimer laser among grating processing parameters. The FBGs were fabricated in a different UV laser irradiation time at 30, 60, 90, and 120 seconds using the same commercial Ge-doped silica core fiber (SMF-28e). It was exposed to gamma-radiation up to a high dose of 34.3 kGy at the dose rate of 106 Gy/min, and then it was analyzed radiation effects by measuring the radiation-induced change in the temperature sensitivity coefficient and Bragg wavelength shift. According to the experimental results, We confirmed that the UV laser irradiation period for grating inscription has a highly effect on the radiation sensitivity of the FBGs. The radiation-induced Bragg wavelength shift by the change of laser irradiation conditions showed a difference more than about 50 %.

• Textile Coloration and Finishing
• /
• v.14 no.2
• /
• pp.77-77
• /
• 2002

Cotton fabrics dipped in cationic agent(3-chloro-2-hydroxypropyl trimethyl ammonium chloride) were irradiated with deep Ultra Violet Rays(UV), in the region of UV-C using the low pressure mercury lamp. The chemical changes of cationized cotton fabric surfaces were investigated by FT-IR analysis. The dyeabilities of the irradiated portions were investigated by dyeing with acid dyes. Deep UV(UV-C) irradiation broke O-H bonds in cotton fiber and oxidized the fibers. The dyeability of the UV irradiated portion were different from that of the portion not irradiated. Various pattern were gained from one bath dig dyeing by pattern mask. The tensile strengths of cotton fabrics were decreased in the UV irradiated portion. Washing fastness of cotton dyeings were good about 3∼4 grade and light fastness were fair about 2∼3 grade.

• Textile Coloration and Finishing
• /
• v.14 no.2
• /
• pp.1-8
• /
• 2002

Cotton fabrics dipped in cationic agent(3-chloro-2-hydroxypropyl trimethyl ammonium chloride) were irradiated with deep Ultra Violet Rays(UV), in the region of UV-C using the low pressure mercury lamp. The chemical changes of cationized cotton fabric surfaces were investigated by FT-IR analysis. The dyeabilities of the irradiated portions were investigated by dyeing with acid dyes. Deep UV(UV-C) irradiation broke O-H bonds in cotton fiber and oxidized the fibers. The dyeability of the UV irradiated portion were different from that of the portion not irradiated. Various pattern were gained from one bath dig dyeing by pattern mask. The tensile strengths of cotton fabrics were decreased in the UV irradiated portion. Washing fastness of cotton dyeings were good about 3∼4 grade and light fastness were fair about 2∼3 grade.

• Applied Biological Chemistry
• /
• v.51 no.4
• /
• pp.276-280
• /
• 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.

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

• Textile Coloration and Finishing
• /
• v.18 no.6 s.91
• /
• pp.49-56
• /
• 2006

Surface treatment using UV irradiation was carried out to improve optical properties of polarizing films. The effects of UV energy of the UV-treated PVA films were investigated by measuring reflectance, surface roughness, contact angles, ESCA, and ATR. Reflectance decreased at wavelength of 450 nm or less and surface roughness increased with increasing UV energy. Water contact angle increased in the irradiated PVA films and surface energy decreased with increase in w energy. An analysis showed that the OH groups were broken and some new groups were introduced such as C=C and C=O bonds together with increased $O_{1s}/C_{1s}$, resulting in the observed surface modification effect. Surface modified PVA polarizing films showed improvement in light transmittance of polarizing films at high wavelength region without deteriorating polarization efficiency, which was not affected by UV irradiation sequence during manufacturing processes such as coloring and drawing.

• Textile Coloration and Finishing
• /
• v.17 no.6 s.85
• /
• pp.27-35
• /
• 2005

Conventional pad- dry-cure(thermo-fixation) process usually produces functional performance on both sides of a fabric. UV curing technique was applied to impart water- and oil-repellent finish effective only on the face of a PET knitted fabric. The preferential one-side coating, by virtue of the limited penetration of UV light, was achieved by W curing after padding of a fluorocarbon agent without special coating or printing equipments. The difference in the functional property of face and back sides was examined by measuring water and oil repellency at each side of the treated fabric. The influence of pre/post-irradiation dose and agent concentration on the performance of the finished fabrics were investigated. While increase in both resin concentration and post-irradiation did not have significant effect on the finish, UV pre-irradiation of PET fabrics caused remarkable influence presumably due to appropriate surface modification of PET fabrics required for facile wetting of the resin. The dimensional stability and color change of the UV cured fabrics measured by FAST and reflectance spectrophotometry showed significantly decreased color difference and increased percent extension compared with the samples pre-irradiated without agent application.

• Environmental Engineering Research
• /
• v.24 no.1
• /
• pp.54-62
• /
• 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.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 2003.11a
• /
• pp.110-110
• /
• 2003

It is well-documented that decreased antioxidant defense system by ultraviolet(UV) irradiation is the most important reason to induce the skin aging, especially photoaging. Chlorogenic acid(CA), a nonflavonoid catecholic compound, is present in the diet as part of fruits, tea, coffee and wine and has been reported to have anti-inflammatory, antimutagenic and anticarcinogenic activities. In this study, we examined the effects of CA on the UV -induced photoaging. Firstly, we investigated the protective effect of CA on antioxidant defense system in HaCaT human keratinocytes after UV irradiation treatment. UV irradiation decreased antioxidant defence enzyme activities of superoxide dismutase, catalase and GSH contents, which were restored by CA. To elucidate the effect of CA, 1% of CA and vehicle were applied to human buttock skin before and after UV irradiation (2MED). CA prevented UV -induced matrix metalloproteinase-1 mRNA expression and procollagen mRNA depression. And CA also increased CD1a(Langerhans cell) expression significantly. Our results suggest that CA has protective effects on UV -induced photoaging by increasing cellular antioxidant defense system. Therefore, CA may be a useful anti-aging agent for cosmetic purpose.