• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.9
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• pp.444-449
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• 2001

In this paper, a novel ultraviolet sensor is presented based on a photoluminescent porous silicon. Porous silicon layer was formed by chemical etching of surface of pn junction in a $HF(48%)-HNO_3(60%)-H_20$ solution. Incident ultraviolet(UV) light is converted to visible light by photoluminescent porous silicon layer, and then this visible light generates electron-hole pairs in the pn junction, which produces a photocurrent flow through the device. In order to maximize detection efficiency, the peak sensitivity wavelength of the pn junction diode was matched with the peak wavelength of Photoluminescence from porous silicon layer. The porous silicon ultraviolet sensor showed a large output current as UV intensity increases and but very low sensitivity to visible light. The detection sensitivity of porous silicon sensor was calculated as 2.91mA/mW. These results are expected to open up a possibility that the present porous silicon sensor can be used for detecting UV light in a visible background, compared to silicon UV detectors which have an undesirable response to visible light.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.276-282
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• 2019

The purpose of this study was to analyze the structure of general filter using ultrafine filter (Profilter), dust collector filter, HEPA (HAPA-High Efficiency Particulate Air) filter, deodorized filters, etc. of air purifiers and to study new types of purified filters that can improve ultrafine dust, harmful gases, and sterilization cleanup performance. The study was also conducted by adding photocatalyst filters to the existing step-by-step filtration filter types, which were proposed in the design three coupling structure filters of the left and right UV-LED installation frames and the photocatalyst coating honeycomb frame. Future research is needed on the effect of photocatalyst filters. This study was to investigate the application and structure of photocatalyst filters to air purifiers.

• Textile Coloration and Finishing
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• v.23 no.1
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• pp.11-20
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• 2011

UV-induced surface copolymerization has been widely applied as a simple, useful and versatile approach to improve the surface properties of textiles. C.I. Reactive Black 5 and acrylic acid (AA) were continuously grafted onto cotton by UV irradiation. The photografting may occur by the copolymerization of AA with the vinylsulfone reactive dye which photochemically converted from the bissulfatoethylsulfone reactive group. The graft yield and color yield were influenced by UV energy, the dye and photoinitiator concentrations, a mole ratio of AA to dye, and pH. The coloration of cotton fabrics having a K/S of 7.0 can be obtained under a UV irradiation energy of 15$J/cm^2$ by the photografting of an aqueous alkaline formulation of 6% dye concentration containing 3% photoinitiator concentration on the weight of monomers, and a 3:1 mole ratio addition of AA to the dye. Furthermore, the photochemically dyed cotton fabrics showed comparable washing (staining) and rubbing fastness to conventional reactive dyeing method except shade change in the wash fastness and light fastness.

• Korean Journal of Materials Research
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• v.18 no.2
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• pp.98-102
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• 2008

The ferroelectric properties of UV irradiated and non-irradiated PZT films prepared via photochemical metal-organic deposition using photosensitive precursors were characterized. Fourier transform infrared spectroscopy showed that complete removal of organic groups was possible through UV exposure of the spin-coated PZT precursor films at room temperature. The measured remnant polarization values of UV-irradiated and non-irradiated PZT films after annealing at $650^{\circ}C$ were 29 and $23\;{\mu}C/cm^2$, respectively. The UV irradiation was found to be effective for the enhancement of the <111> growth orientation and ferroelectric property of PZT film and in the direct patterning in the fabrication of micro-patterned systems without dry etching.

• Journal of Adhesion and Interface
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• v.10 no.4
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• pp.191-198
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• 2009

UV-curable aliphatic epoxy acrylates were prepared by the reaction of glycerol diglycidyl ether (GDE) with 2-carboxyethyl acrylate (2-CEA) or 2-hydroxyethyl acrylate (2-HEA). The structures of the epoxy acrylates were characterized by FT-IR, $^1H$-NMR, and $^{13}C$-NMR and the yield was obtained by prep-LC. The UV- and the thermal-curing behaviors of the product were investigated using photo-DSC and DSC, respectively. The reactivity of 2-CEA was higher than 2-HEA and the yield of the product (GEA-C) which was prepared using 2-CEA was about 83%. The maximum UV-curing time ($T_{max}$) of the GEA-C contained non-reactive components and by-product was about 10 seconds. The GEA-C showed low color difference (${\Delta}E^*$), low viscosity, and good thermal stability - its value was 2.51, 192 cps, and $299^{\circ}C$ (at 5% weight loss), respectively. The activation energies ($E_a$) of thermal-curing reaction calculated from Kissinger and Ozawa-Flynn-Wall method were 91~92 kJ/mol.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.1
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• pp.138-145
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• 2010

The combined effect of 50 ppm aqueous chlorine dioxide ($ClO_2$) or 0.5% fumaric acid with $5 kJ/m^2$ ultraviolet-C (UV-C) on the postharvest quality of "Flamengo" strawberries was examined. After non-thermal treatment, the samples were stored at $4\pm1^{\circ}C$ for 12 days. The combined treatment of fumaric acid/UV-C reduced the initial populations of total aerobic bacteria and yeast and molds in the strawberries by 2.09 and 2.02 log CFU/g, respectively, compared to those of the control. In addition, after 12 days of storage the yeast and molds population in the combined treatment was 1.72 log CFU/g, compared to 5.10 log CFU/g for the control, resulting in a significant decrease of 3.38 log CFU/g. Postharvest treatments used in this study caused negligible changes in the color of the strawberries. Sensory evaluation results indicated that the combined postharvest treatment provided better sensory scores than did the control. In particular, the overall acceptability scores were higher for the combined treatment groups after 5 days of storage. These results suggest that combined treatment of either 50 ppm $ClO_2$ or 0.5% fumaric acid with $5 kJ/m^2$ UV-C can be useful for maintaining the quality of strawberries.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.6
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• pp.264-271
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• 2007

The inorganic pigments of $Fe_2O_3-CoO-Cr_2O_3-MnO_2$ were synthesized by the co-precipitation method. $FeCl_3,\;CoCl_2,\;CrCl_3\;and\;MnCl_2$ are used for the starting raw materials, and 2 N-KOH for precipitator. $MnCl_2$ is secured with 10 mole%, and 6 composition ratios are used with three ingredients to synthesize the pigments. The samples were calcined at $1350^{\circ}C/1.5h$. The resulting pigments were characterized by using XRD, FT-IR, SEM, and UV spectrophotometer. 6wt% pigments were applied to lime glaze and lime-barium glaze respectively firing at $1260^{\circ}C$ for oxidation atmosphere and $1240^{\circ}C$ for reduction one. The results of color analysis by using UV spectrophotometer showed black, bluish black and dark grayish green.

• Korean Journal of Plant Resources
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• v.8 no.2
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• pp.135-141
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• 1995

The experiment was carried out to clarify the effects of air temperature, light exposure and UV light on the growth and anthocyanin syntheses of Glehnia littoralis Fr. Schm. The major pigment of purfied aglycone of Glehnia littoralis Fr. Schm. was identified as cyanidin by TLC and HPLC analysis. The anthocyanin Syntheses was promoted at low temperature and in the treatment of light exposure (12hrs a day) for 4-6 days after shading. The plants grown under UV-cut film had less anthocyanin content those tose under UV-transmission film.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.5
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• pp.643-648
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• 2013

In this study, degradation was observed by irradiating UV rays to the polymer insulators which have been widely used in outdoor electric power facilities. For an indoor accelerated UV test, 0.55 w/m2 of UV rays were applied using a xenon-arc method. A UV detection system with 65 ${\phi}mm$ in diameter, 100 mm in length and 1.0 of brightness (F/#) has been designed. Even though efflorescence on the surface of polymer insulators wasn't observed according to the accelerated UV test. UV rays were detected at around 50% and 40% of insulation breakdown in EPDM and silicone-type insulators respectively. As degradation continued because of an indoor accelerated UV test, breakdown voltage with which UV rays can be detected in an early stage decreased as well. A silicone polymer insulator would be severer than EPDM polymer insulator in terms of surface degradation because of UV strength against $V_m/V_{BD}$ was high in silicone polymer insulators. UV strength in silicone-type insulators increased at 1,000 $kJ/m^2$ because contact angle at the intial stage sharply decreased to from $113^{\circ}$ to $92.1^{\circ}$.

• Journal of Photoscience
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• v.1 no.2
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• pp.135-141
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• 1994

Elevated near-UV radiation, containing a large amount of UV-B and a small amount of UV-C, inhibited the development of leaves and tillers, the increase in biomass production, the elongation of plant height, the photosynthetic rate and the chlorophyll content in rice plants in a phytotron. Elevated UV-B radiation filtered through cellulose diacetate film or UV-31 cut filter (transmission down to 290 nm) similarly suppressed each growth component above. Near-UV radiation-caused injuries were alleviated either by elevated CO$_2$ atmosphere or by exposure to high irradiance-visible radiation. On the basis of these findings, we examined cultivar differences in the resistance to UV radiation-caused injuries among 198 rice cultivars belonging to 5 Asian rice ecotypes ( aus, aman, boro, bulu and tjeleh) from the Bengal region and Indonesia and to Japanese lowland and upland rice groups. It was shown that .various cultivars having different sensitivities to the effects of near-UV radiation were involved in the same ecotype and the same group, and that the Japanese lowland rice group and the boro ecotype were more resistant. Among Japanese lowland rice cultivars, Sasanishiki (one of the leading varieties in Japan) exhibited more resistance to near-UV radiation, while Norin 1 showed less resistance, although these two cultivars are closely related. It was thus indicated that the resistance to the inhibitory effects of near-UV radiation of rice cultivars is not simply due to the difference in the geographical situation where rice cultivars are cultivated. From the genetic analysis of resistance to the inhibitory effects of UV radiation on growth of rice using F$_2$ plants generated by reciprocally crossing Sasanishiki and Norin 1 and F$_3$ lines generated by self-fertilizing F$_2$ plants, it was evident that the resistance to the inhibitory effects of elevated near-UV radiation in these rice plants was controlled by recessive polygenes.