• Journal of Technologic Dentistry
• /
• v.42 no.2
• /
• pp.113-120
• /
• 2020

Purpose: This study is to compare and analyze the shrinkage of the specimen after UV irradiation of UV cured resin at 5, 15, and 30 minutes. Methods: A cylindrical UV cured specimen was produced using a stainless steel mold. UV cured resin specimens were prepared in three groups: 5 minutes cured (5M), 15 minutes cured (15M), and 30 minutes cured (30M). The measurement was made in total 3rd. The measurement was made in total 3rd. The primary measurement was made after 24 hours using a digital measuring instrument. The 2nd and 3rd measurements were deposited in a constant temperature water bath and the shrinkage was measured. The measured data was calculated by referring to the ASTM C326 linear measurement calculation method. T-test and One-way ANOVA were performed to test the significance between groups. The post-test was conducted with Tukey (α=0.05). Results: When the inner diameter and the outer diameter of the three groups not placed in the water bath were compared and analyzed, the contraction was the smallest at 6.8% in the 5M group, and the contraction was the largest at 7.3% in the 30M group. In the outer diameter, the contraction of the 5M group was the smallest at 3.5%, and the contraction of the 30M group was the largest at 4.5%. Shrinkage decreased in all three groups immersed in a water bath for 3-7 days. Conclusion: In the UV cured resin specimen, the shrinkage increased as the amount of UV irradiation increased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1998.06a
• /
• pp.109-112
• /
• 1998

In this paper, we studied on electro-optical (EO) characteristics of photo-aligned twisted nematic (TN)-LCD. We obtained that uniform LC alignment in TN-LCD with linearly polarized ultraviolet (LPUV) light irradiation on polyimide (PI) surface increases according to increasing irradiation time for 10 to 60 min. The voltage-transmittance and response time characteristics of photo-aligned TN-LCD with UV light irradiation time of 60 min were almost same in comparison with conventional TN-LCD were observed. From the results, we suggest that photo-aligned TN-LCD with LPUV light irradiation on PI surface is useful in applying LCD as for rubbing-free treatment method.

• The Korean Journal of Food And Nutrition
• /
• v.30 no.5
• /
• pp.1113-1118
• /
• 2017

The objective of this study was to investigate the non-thermal sterilization effect of methods such as high hydrostatic pressure (HHP) and UV-irradiation (specifically with regard to the storage stability and shelf-life of carrot juice. The microbial counts of the non-sterilized product increased from 5.51 to 7.34 log CFU/mL up to the fifth day, and then decreased to 5.46 log CFU/mL at six days. UV-irradiation was increased from 2.37 to 4.92 log CFU/mL. HHP was maintained under the 3 log CFU/mL. The pH of UV-irradiation and HHP was maintained withing the range of 6.29~6.30 and 6.20~6.22 during storage. However, the pH arising from non-sterilization decreased from 6.31 to 4.49. The color of non-sterilization changed significantly during storage, but UV-irradiation and HHP were similar during storage. The ${\beta}$-carotene content of non-sterilization was noted to have decreased from 269.45 to $65.19{\mu}g/mL$ during storage. The UV-irradiation and HHP decreased from 263.46 and $268.35{\sim}281.16{\mu}g/mL$ to 243.42 and $244.09{\sim}269.29{\mu}g/mL$, respectively. In conclusion, these findings suggest that HHP can be used for the pasteurization, or sterilization, of carrot juice and the optimal condition is two minutes.

• Horticultural Science & Technology
• /
• v.34 no.4
• /
• pp.596-606
• /
• 2016

The growth and contents of anthocyanins and ascorbic acid in lettuce(Lactuca sativa L., 'Jeokchima') as affected by supplemental UV-A LED irradiation under different light quality and photoperiod conditions were analyzed in this study. Five light qualities, namely B (blue LED), R (red LED), BUV (blue LED+UV-A LED), RUV (red LED+UV-A LED) and Control (white fluorescent lamps) with photoperiods of 12/12 hours (day/night), 16/8 hours, or 20/4 hours were provided to investigate the effects of light quality and photoperiod on the growth and accumulation of anthocyanins and ascorbic acid in lettuce leaves. As measured 28 days after transplanting, the number of leaves, leaf length, leaf width, leaf area, shoot fresh weight and dry weight of lettuce were significantly affected by light quality and photoperiod. The number of leaves, leaf length, leaf width, leaf area, shoot fresh weight and dry weight of lettuce grown under R treatment increased with increasing light period. By contrast, leaf development was inhibited, but chlorophyll content increased, under B treatment. Supplemental UV-A irradiation significantly decreased leaf length, leaf width, leaf area and shoot fresh weight. Anthocyanins in lettuce increased significantly with decreasing dark period under B treatment. A synergistic effect of supplemental UV-A LED irradiation on anthocyanins accumulation was found for lettuce leaves grown under R treatment but not B treatment. Ascorbic acid in lettuce was greatly affected by photoperiod. Ascorbic acid content at BUV and RUV treatments increased by 20-30% compared to without UV-A LED irradiation. From these results, it was concluded that growth and contents of anthocyanins and ascorbic acid in lettuce are significantly affected by supplemental UV-A LED irradiation. The results obtained in this study will be informative for efforts to improve the nutritional value of leafy vegetables grown in plant factories.

• Journal of Korean Society of Water and Wastewater
• /
• v.23 no.1
• /
• pp.69-75
• /
• 2009

The characteristics of disinfection and organic removal were investigated with pulse UV lamp in this study. The intensity and emission wavelength of pulse UV Lamp were compared with low pressure UV lamp. The emission spectrum range of pulse UV lamp was between 200 and 400 nm while the emission spectrum of low pressure UV lamp was only single wavelength of 254nm. 3 Log inactivation rate of B. subtilis spore by pulse UV and low pressure UV irradiation was determined as $44.71mJ/cm^2$ and $57.7mJ/cm^2$, respectively. This results implied that wide range of emission spectrum is more effective compared to single wavelength emission at 254nm. 500ng/L of initial 2-MIB concentration was investigated on the removal efficiency by UV only and $UV/H_2O_2$ process. The removal efficiency of UV only process achieved approximately 80% at $8,600mJ/cm^2$ dose. 2-MIB removal rate of $UV/H_2O_2$ (5 mg/L $H_2O_2$) process was 25 times increased compared to UV only process. DOC removal efficiency for the water treatment plant effluent was examined. The removal efficiency of DOC by UV and $UV/H_2O_2$ was no more than 20%. Removal efficiency of THMFP(Trihalomethane Formation Potential), one of the chlorination disinfection by-products, is determined on the UV irradiation and $UV/H_2O_2$ process. Maximum removal efficiency of THMFP was approximately 23%. This result indicates that more stable chemical structures of NOM(Natural Organic Matter) than low molecule compounds such as 2-MIB, hydrogen peroxide and other pollutants affect low removal efficiency for UV photolysis. Consequently, pulse UV lamp is more efficient compared to low pressure lamp in terms of disinfection due to it's broad wavelength emission of UV. Additional effect of pulse UV is to take place the reactions of both direct photolysis to remove micro organics and disinfection simultaneously. It is also expected that hydrogen peroxide enable to enhance the oxidation efficiency on the pulse UV irradiation due to formation of OH radical.

• Elastomers and Composites
• /
• v.41 no.3
• /
• pp.182-193
• /
• 2006

The retardation effects of a new polymeric UV stabilizer, DGEBA-HALS, on the UV degradation of SBR and NR were investigated in this study. The UV degradation behaviors of three different rubber compounds, without any photostabilizer and with commercial Cyabsorb UV-3529 and DGEBA-HALS, were compared. Also, the physical characteristics such as Young's modulus, tensile strength, blow-off deformation and crosslink density were examined. The Young's modulus was increased by UV irradiation for all samples, and the tensile strength, after UV irradiation, of the compound with UV stabilizer was better than that of the compound without stabilizer. Especially, the tensile strength of UV irradiated NR was improved by adding DGEBA-HALS. The results of blow-off deformation were in accord with those of Young's modulus. The degree of transmission of SBR compounds obtained from UV-vis transmission spectra was improved about 4% by adding the UV stabilizer. Commercial Cyabsorb UJV-3529 and DGEBA-HALS showed similar trends of transmission. The SEM photographs of SBR surface showed that the size of cracks created by UV irradiation became smaller by adding UV stabilizer. In particular, it is observed that the stabilization effect of DGEBA-HALS was better than that of commercial Cyabsorb UV-3529.

• Proceedings of the KIEE Conference
• /
• 1999.07d
• /
• pp.1882-1884
• /
• 1999

The photoisomerization of functional polyimide was investigated in the various temperatures and UV(360nm) & visible(450nm) light irradiation. The absorption spectrum of azobenzene containing polyamic acid in a mixture of N,N-dimethylacetamide and benzene(1:1 by volume) solution was induced photoisomerization by UV and visible light irradiation. The absorption spectrum of LB films are also induced photoisomerization by UV and visible light irradiation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1997.04a
• /
• pp.116-119
• /
• 1997

We investigated new type non-robbing liquid crystal (LC) alignment techniques in the cell with slanted non-polarized ultraviolet (UV) irradiation on polyimide (Pl) film. It is shown that the uniform alignment for nematic (N) LC is obtained by using slanted non-polarized UV irradiation on Pl surface. We successfully obtained that the pretilt ang1e of NLC is generated about 3 degree in the LC cells by using slanted non-polarized UV irradiation with 70 degree on Pl surface. We consider that the pretilt angle generation for NLC is attributed to interaction between the LC molecular and the PI surface. We conclude that the uniform LC alignment is attributed to anisotropic dispersion force effect due to photo depolymerization of polymer on Pl surface.

• Microbiology and Biotechnology Letters
• /
• v.22 no.6
• /
• pp.584-592
• /
• 1994

Several mutation procedures have been compared to obtain an ethanol-tolerant Saccha- romyces diastaticus strain secreting glucoamylase. These procedures include spontaneous mutation, EMS treatment, UV irradiation, and combination of EMS treatment and UV irradiation. All these methods were followed by adaptation of the yeast cells to gradually higher ethanol concentration. Among these procedures, the combined method of EMS treatment and UV irradiation gave the promising result, i.e. the ethanol tolerance of the yeast increased from 11.5%(v/v) to 14.0%(v/v). Respiratory deficient petite mutants of industrial and ethanol-tolerant yeast strains have been isola- ted and hybridized with haploid S. diastaticus strains. The resulting hybrids showed increased ethanol tolerance and starch-fermentability.

• Korean Journal of Medicinal Crop Science
• /
• v.18 no.3
• /
• pp.191-200
• /
• 2010

Anthocyanin and polyphenolic compounds present in fruits of mulberry (Morus alba L.) were determined and the influence of temperature and UV irradiation on stability of the anthocyanin-copigment complex were investigated. The copigmentation substance selected in non-anthocyanin fraction from mulberry for the study included: phenolic acid (hydroxybenzoic acid) and flavonoid (quercetin-3-O-$\beta$-D-glucopyranoside). The copigmentation effect increased with the copigment content. UV irradiation had a stronger degradation effect on the copigmentation complex than heating at $80^{\circ}C$. The non-anthocyanin fraction of mulberry and isolated flavonoid (quercetin-3-O-$\beta$-D-glucopyranoside) from mulberry fruit predominated over other copigment substances.