• Title, Summary, Keyword: UV irradiation

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Removal and Decomposition of Organochlorine Compounds in Water Using UV Irradiation (자외선에너지를 이용하여 물속에 함유된 유기염소계 화합물의 분해 및 제거)

  • Kim, Jong Hyang
    • Applied Chemistry for Engineering
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    • v.10 no.1
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    • pp.30-34
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    • 1999
  • Photolysis behavoirs of pesticides(Chlorothalonil and Endosulfan) over UV irradiation UV irradiation with pH 3.0 and irradiation with 3.5% salt were studied. The analyses of pesticides were carried out using gas chromatograph with an electron-capture detector, total organic carbon, and Ion chromatograph, respectively. The reactions were conducted in a alumium annular reactor equipped with a low pressure mercury multilamp ($8W{\times}6$) and initial concentration was 10 ppm. Chlorothalonil was almost photodegraded by UV irradiation, UV irradiation with pH 3.0 and 3.5% salt within 30 min of reaction time. Endosulfan-${\alpha}$,${\beta}$(100%) were photodegraded to 38% of Endosulfan-${\alpha}$ and 25% of Endisulfan-${\beta}$ by UV irradiation. Endosulfan-${\alpha}$(83%) was photodegraded to 66% by UV irradiation, 70% by UV irradiation and pH 3.0 and 75% by UV irradiation and 3.5% salt. Endosulfan-${\beta}$(16%) was photodegraded to 80% by UV irradiation, 98% by UV irradiation and pH 3.0 and 90% by UV irradiation and 3.5% salt.

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Evaluation on Physical and Mechanical Properties of Wood Plastic Composites Treated under Ultraviolet Irradiation (자외선을 처리한 목재 플라스틱 복합재의 물리 및 역학적 성질 평가)

  • Lee, Jong-Shin;Kim, Soung-Joon
    • Journal of the Korea Furniture Society
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    • v.26 no.4
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    • pp.428-434
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    • 2015
  • In this study, we received each wood plastic composites (WPC) from three manufacturers. These WPCs were evaluated regarding their physical and mechanical properties of both before and after accelerated weathering by ultraviolet (UV) irradiation. The total time of exposure of the WPCs to UV irradiation was 1800 h. The water absorption, volumetric swelling and shrinkage of WPCs did not affected by UV irradiation. Among the mechanical properties, there was no significant differences in bending strength and screw withdrawal resistance of UV treated WPCs compared with those of reference WPCs. However, surface hardness of WPCs showed decrease under UV irradiation. Stereoscopic microscopy observation revealed deterioration of the surface layer polymer in all weathered WPCs by UV. Exposure of the WPCs to UV irradiation caused decomposition and disappearance of the polymer layer. From this result, we can estimate that damage of polymer by UV led to a decrease in the surface hardness of the WPCs. The wood flours retained original shape after accelerated weathering by UV irradiation.

The degradation of EVA for the protection of solar cell by UV-rays irradiation (자외선 조사에 따른 태양전지 보호용 EVA의 열화)

  • 김규조;연복희;김승환;김완태;허창수
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.177-180
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    • 2000
  • We studied the degradation of EVA for the protection of solar cell by UV-rays irradiation. We investigated the reduction of electrical efficiency, photo transmmitance and degradation of EVA by UV-rays irradiation. We utilized the UV irradiation equiped with fluorescent 313nm UV lamp and radiated for 400 hours. For the chemial analysis, we used the UV-vis spectrometer, XPS and examined the degradation mechanism by UV irradiation. It is found that the discolored phenomena, the decrease of photo transmmitance and oxidation reaction is occured by UV irradiation on the EVA sample for the protection of solar cell.

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Effect of UV Irradiation on the Color and Mechanical Properties of Catechu Dyed Fabrics (자외선 조사가 아선약 염색 직물의 색상 및 역학적 특성에 미치는 영향)

  • Nam, Ki-Yeon;Lee, Jung-Soon
    • Korean Journal of Human Ecology
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    • v.20 no.5
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    • pp.1009-1023
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    • 2011
  • This study was carried out to investigate the variations of catechu dyed fabrics under UV irradiation. Catechu dyed cotton and silk fabrics mordanted with Fe and Cu were irradiated with UV under dry and wet conditions, and then were evaluated on color changes and mechanical properties. Owing to UV irradiation, the K/S values of catechu dyed cotton fabrics increased until a certain amount of time but those of catechu-dyed silk fabrics increased continuously. Cu mordanting cotton fabrics showed the smallest changes due to the UV treatment, and silk fabrics mordanted with Fe showed the largest changes. Wetted fabrics were accelerated maillard browning by UV. Un-mordanted cotton fabrics treated with UV under dry conditions changed its YR color to Y, but changed its Y color to YR under wet conditions. However, mordanted cotton fabrics treated with UV didn't change their color. Dyed silk fabrics except those Fe mordanted and in wet conditions continued to keep their color after UV irradiation. Silk fabric mordanted with Fe under wet conditions changed its Y color to YR by UV irradiation. UV irradiation didn't affect the mechanical properties of catechu-dyed cotton and silk fabrics in any significant way.

Electrical and Optical Properties in Transparent Conducting Oxides: Effect of Ultra Violet Irradiation

  • So, Byung-Soo;Hwang, Jin-Ha
    • Journal of the Semiconductor & Display Technology
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    • v.6 no.1
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    • pp.65-69
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    • 2007
  • A design of experiments was applied in order to investigate the effect of processing variables in UV irradiation on the electrical/optical properties in indium-zinc oxide thin films, The processing variables, equivalently input variables are listed as UV irradiation time, oxygen flow rate, and chamber pressure. The statistical significance of Ultra Violet (UV) treatment was confirmed using a paired-t test. The full factorial $2^3$ design was employed to determine significant main and interaction effects in UV irradiation process. The chamber pressure and the interaction between UV irradiation time and $O_2$ flow rate were found to be statistically significant at the significance level of 0.1. Furthermore, the optimized approach was proposed in achieving the improved conductivity after UV irradiation.

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Decomposition of Organophosphorous Compounds with Ultraviolet Energy(UV-C) (자외선에너지(UV-C)를 이용한 유기인계 화합물의 분해)

  • Kim, Jong-Hyang;Min, Byoung-Chul
    • Applied Chemistry for Engineering
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    • v.9 no.1
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    • pp.28-32
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    • 1998
  • Two organophosphorous insecticides, Dichlorovos and Chloropyrifos were degraded in the presence of UV irradiation, UV irradiation with $TiO_2$ powder and UV irradiation with sea sand using low pressure mercury lamp. The identification of these compounds was carried out by gas chromatograph with a nitrogen-phosphorous detector, Total Organic Carbon and Ion Chromatograph, respectively. Both dichlorvos and chloropyrifos, UV irradiation with sea sand were more degradable than UV irradiation and UV irradiation with $TiO_2$ powder. The final products were $Cl^-$ in Dichlorvos, $Cl^-$ $SO_4{^{2-}}$ in Chloropyrifos, respectively.

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Effect of UV-C and Electron Beam Irradiation of on the Quality of Rice Wine (Makgeolli) (UV-C 및 전자선 조사가 막걸리의 품질에 미치는 영향)

  • Kim, Hyun-Joo;Lee, Kyung Haeng;Yong, Hae In;Jo, Cheorun
    • Korean Journal of Food Preservation
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    • v.20 no.1
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    • pp.45-51
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    • 2013
  • This study was conducted to evaluate the changes in the quality of rice wine (Makgeolli) treated with UV-C and electron beam (EB) irradiation during its storage at $4^{\circ}C$ for 15 days. The EB irradiation was found to be more effective than the UV-C irradiation for microbiological control. The pH tended to be increased by UV-C, EB irradiation, and storage period. Acidity was significantly higher in rice wine treated with EB irradiation than those of control and UV-C irradiation during storage period. The $L^*$-value of the samples treated with UV-C and EB irradiation tended to be proportionately higher than that of the control, but this was not consistent during storage period. The $a^*$-value of the sample treated with EB was higher than that of the others, but this was not consistent during the storage period. The reducing sugar content was higher in the control at day 0, but it rapidly decreased compared with the control during the storage. The results indicate that EB irradiation was more effective than UV-C irradiation in controlling microorganisms of rice wine. However, a further study is needed to minimize the rice wine quality deterioration caused by UV-C or EB irradiation during storage.

Relationship between the pretilt angle generation and the polarization component with oblique polarized UV light irradiation on polyimide surface. (폴링미드표면에 편광된 UV광을 경사조사시의 프리틸트각의 발생과 편광성분의 상호관계)

  • 서대식;박두석
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.12 no.1
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    • pp.75-80
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    • 1999
  • In this study, we have investigated the relationship between the generation of pretilt angle and the polarization component in cells with UV light irradiation on polyimide (PI) surface. It was found that the generated pretilt angle is about $1.4^{\circ}$ with S-polarized UV light irradiation of $75^{\circ}$ on PI surface; it may be attributed to the asymmetry triangular of polymer surface with oblique S-polarized UV light irradiation on PI surface. Also, we measured that the generated pretilt angle is about $2.0^{\circ}$ with oblique P polarized UV light irradiation of $75^{\circ}$ on PI surface. Consequently, we suggest that the generated pretilt angle of the NLC is attributed to the interaction between the LC molecules and the polymer surface with oblique polarized UV light irradiation on PI surface.

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UV Effect on Plant Growth

  • Kondo, Noriaki;Tou, Seiji;Takahashi, Shinya;Nakajima, Nobuyoshi
    • Journal of Photoscience
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    • v.9 no.2
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    • pp.158-161
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    • 2002
  • UV-B radiation gives harmful effects on plants, such as production of several types of DNA lesions, and growth inhibition. On the other hand, plants have some protective mechanisms, including filtering effect due to accumulation of phenolic compounds in epidermal cells and reactivation of DNA lesions, which are enhanced by UV-B irradiation. We have investigated the mechanism of UV-B effects on plants using cucumber seedlings as plant materials. Cucumber plants were cultivated in an artificially lit growth chamber. Supplemental UV-B irradiation, of which intensity was almost equal to the level of natural sunlight, retarded the growth of first leaves. The growth retardation must result trom the inhibition of cell division and/or cell growth. Microscopical observation of leaf epidermis suggested that the growth retardation might be mainly caused by cell growth inhibition. The retardation was, however, restored within 2 or 3 days after the termination of UV-B irradiation. It is known that UV-B irradiation lowers the activity of photo system II (PS II). In the present experimental conditions, however, UV-B irradiation has little effect on PS II activity as estimated by chlorophyll fluorescence. The stomatal conductance, a major factor determining photosynthetic rate, of first leaves increased during the growth. The increase of stomatal conductance was suppressed by UV-B irradiation and restored by termination of the irradiation. It has not been clear, however, what mechanisms are involved in the suppression of increase of stomatal conductance.

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Investigation of Potential Photoreactivation of Pseudomonas aeruginosa after LP or MP UV Irradiation (저압 및 중압 자외선 조사에 의해 불활성화된 Pseudomonas aeruginosa의 광회복능 조사)

  • Mun, Sung-Min;Cho, Min;Yoon, Je-Yong
    • Journal of Korean Society of Water and Wastewater
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    • v.20 no.5
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    • pp.755-761
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    • 2006
  • Recently, there is growing interest in ultraviolet (UV) irradiation as a disinfection technic in drinking water production due to its effectiveness to inactivate microorganisms such as Crytosporidium parvum without forming disinfection byproducts. However, UV disinfection is known for its drawback such as photoreactivation. Despite many works concerning the photoreactivation, most of works were focused on indicator or non pathogenic microorganisms. The objective of this study is to examine the photoreactivation of Pseudomonas aeruginosa which is an opportunistic pathogen as UV radiation by LP and MP UV lamp was applied. The result showed that P. aeruginosa had high photo repair efficiency regardless of the type of UV irradiation. Both of the effective log repair values of LP and MP UV irradiation were found approximately 2.6 log. In addition, photo repaired P. aeruginosa was not significantly different in forming biofilm in comparison with non treated P. aeruginosa.