• Electrical & Electronic Materials
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• v.10 no.2
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• pp.166-171
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• 1997

The photomachinable glass-ceramics of Ag and CeO$_{2}$ added to Li$_{2}$O-Al$_{2}$O$_{3}$-SiO$_{2}$-K$_{2}$O glass system was investigated as a function of UV irradiation time. The temperature of optimum nucleation and crystal growth temperature were confirmed at 525.deg. C, 630.deg. C respectively using DTA and TMA. The phases of Li$_{2}$O.SiO$_{2}$ habit were lath-like and/or dendrite type and [002] direction of Li$_{2}$O.SiO$_{2}$ / Li$_{2}$O.2SiO$_{2}$ phases were changed according to the UV irradiation time by 400 W, 362 nm UV light source. Under that condition, the optimum UV irradiation time was 5 min.

• Journal of Bio-Environment Control
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• v.32 no.4
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• pp.342-352
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• 2023

Ultra-violet (UV) light is one of abiotic stress factors and causes oxidative stress in plants, but a suitable level of UV radiation can be used to enhance the phytochemical content of plants. The accumulation of antioxidant phenolic compounds in UV-exposed plants may vary depending on the conditions of plant (species, cultivar, age, etc.) and UV (wavelength, energy, irradiation period, etc.). To date, however, little research has been conducted on how leaf thickness affects the pattern of phytochemical accumulation. In this study, we conducted an experiment to find out how the antioxidant phenolic content of kale (Brassica oleracea var. acephala) leaves with different thicknesses react to UV-A light. Kale seedlings were grown in a controlled growth chamber for four weeks under the following conditions: 20℃ temperature, 60% relative humidity, 12-hour photoperiod, light source (fluorescent lamp), and photosynthetic photon flux density of 121±10 µmol m^-2 s^-1. The kale plants were then transferred to two chambers with different CO₂ concentrations (382±3.2 and 1,027±11.7 µmol mol^-1), and grown for 10 days. After then, each group of kale plants were subjected to UV-A LED (275+285 nm at peak wavelength) light of 25.4 W m^-2 for 5 days. As a result, when kale plants with thickened leaves from treatment with high CO₂ were exposed to UV-A, they had lower UV sensitivity than thinner leaves. The Fv/Fm (maximum quantum yield on photosystem II) in the leaves of kale exposed to UV-A in a low-concentration CO₂ environment decreased abruptly and significantly immediately after UV treatment, but not in kale leaves exposed to UV-A in a high-concentration CO₂ environment. The accumulation pattern of total phenolic content, antioxidant capacity and individual phenolic compounds varied according to leaf thickness. In conclusion, this experiment suggests that the UV intensity should vary based on the leaf thickness (age etc.) during UV treatment for phytochemical enhancement.

• 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.

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.507-508
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• 2006

Sol-gel 및 MCVD 공정을 사용하여 Ag 가 함유된 광섬유를 제조하였다. KrF 엑시머 레이저에서 출력된 248 nm 의 UV 빔을 광섬유에 조사한 경우 450 nm 를 중심으로 광흡수가 6 dB/cm 로 급격히 증가하는 것을 확인할 수 있었으며, 이는 UV 레이저 조사에 의한 Ag 나노입자 형성에 따른 것으로 추측된다.

• Journal of Bio-Environment Control
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• v.12 no.4
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• pp.252-258
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• 2003

This experiment was performed to investigate the effect of UV-B (4 kJ${\cdot}m^{-2}{\cdot}d^{-1}$) irradiation and growth inhibitor (50 mg${\cdot}L^{-1}$ diniconazole, 500 mg${\cdot}L^{-1}$) treatment on the overgrowth retardation and the growth and yield afterplanting in plug-grown cucumber, tomato, and hot pepper sedlings. Stem length of UV-B-irradiated and iniconazole-treated seedlings was shortened by 38 and 35%^ in cucumber, 37 and 41% in tomato, and 23 and 23% in hot pepper, respectively, compared with non-treated seedlings. While retarding effect ofhexaconazole waslower that that of UV-B or diniconazle. Leaf area and dry weight alson decreased but ldaf thickness increased in UV-B irradiated or growth-inhibitor-treated seedlings. Even thouth the plant height and leaf area of UV-B-irradiated seedlings ant seedling stage were shorter and smaller that those ofnon-treatedd seedlings, they were recovered to the similar level to the growth of non-treated seedlings 20to 30days after trasplantin. The diconazole-and hexaconazole-treated seedlings were delayed recovery to their normal growth, Fruit yiedl of UV-V-irradiated hot pepper and tomato slightly increased but UV-B irradiated cucumer had similar yield to growth-inhibitor-treated one. It suggested that the use of UV-B irradiation could become a reliable tool of overgrowth retardation of plug-grown vegetable seedlings in greenhouse.

• Food Science and Preservation
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• v.20 no.1
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• pp.81-87
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• 2013

Agri-food garlic has been recognized as healthful because of its antibacterial, anticancer and antioxidant effects. As such, its consumption is steadily increasing. This study was conducted to amplify the healthful ingredient of garlic, allicin, using light irradiation. The following conclusions were drawn from the investigation of peeled garlic under various conditions like fluorescent lighting, color (green, yellow, blue and red) and ultraviolet light (UV-A, UV-B and UV-C). The allicin content increased most with the 15-second $0.129W/m^2$ (40 W) UV-B treatment of the garlic at a 700 mm distance from the light source. At the treatment of the garlic with 126 lx (40W) red light for 24 hours at a 700 mm distance from the light source, its allicin content increased from $15.15{\pm}0.25mg/g$ to $15.15{\pm}0.34mg/g$, for a 10-percent amplification effect. Therefore, it is believed that the healthfulness of garlic can be amplified through irradiation processing of its healthful ingredient, allicin, and the development of its processing unit.

• Journal of Life Science
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• v.24 no.5
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• pp.467-475
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• 2014

Sea buckthorn (Hippophae rhamnoides L.) is a well-known and rich source of biologically active compounds, such as flavonoids, carotenoids, steroids, vitamins, tannins, and oleic acid. The effects of sea buckthorn fruit extract (SBFE) on ultraviolet (UV)-induced cell death was investigated in SK-MEL-2 cells cotreated with UV and a low concentration (LoC), medium concentration (MeC), or high concentration (HiC) of SBFE. Cell viability gradually decreased in accordance with an increase in the UV dose. The cell viability of the UV+SBFE cotreated cells increased significantly compared to that of UV+vehicle-treated cells during the application of an appropriate UV radiation dose (400 mJ). In addition, the number of 4',6-diamidino-2-phenylindole (DAPI), propidium iodine (PI)-, and annexin V-stained apoptotic cells was higher in the UV+vehicle-treated cells than in the UV untreated cells. The decrease of apoptotic cell numbers varied in each treated group, but it was most significant in the SBFE-treated group. The number of PI-stained cells dramatically decreased in accordance with the concentration of SBFE, and the maximum decrease was detected in the UV+HiC-treated group. In addition, Bax expression increased and Bcl-2 expression decreased in the SBFE-treated group compared with the UV-only treated group. The level of caspase-3 remained constant in all the groups. These results suggest that SBFE may contribute to a recovery from UV-induced cell death through the regulation of apoptotic protein expression and that it may have potential therapeutic utility in ameliorating UV-induced skin ageing.

• Applied Chemistry for Engineering
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• v.26 no.2
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• pp.224-228
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• 2015

The carbon precursor pitch from pyrolyzed fuel oil (PFO), by-product of Naphta cracking process (NCC), was prepared through heat and UV irradiation treatments with various concentrations of $AlCl_3$, which is a new pitch preparation method. The reformed pitches were characterized by measuring their elemental composition, chemical structure of components, molecular weight distribution, and softening point. The oxygen contents of reformed pitch increased as increasing $AlCl_3$ amounts on the other hand, the carbon and hydrogen contents were not nearly changed. UV irradiated reformed pitches were composed of more aromatic carbon compounds than that of using only heat-treatment without any UV irradiation. The addition of $AlCl_3$ catalyst was ineffective on the aromaticity of reformed pitches. The softening point of prepared pitches was in the range of $103.3{\sim}168.9^{\circ}C$. Also the yield of prepared pitch increased from 48% to 80% when 5 wt% of $AlCl_3$ was added during the heat and UV irradiation reforming. It is expected that the UV irradiation reforming method can be practical and helpful to produce high yields of pitches with diverse properties.

• Journal of Adhesion and Interface
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• v.18 no.3
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• pp.134-140
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• 2017

In this study, we made UV cured acrylic pressure sensitive adhesive containing silicone-urethane-acrylate (SUA) oligomer for a coating on protective film and investigated the effect of SUA oligomer content and UV-dose on adhesion properties. The results illustrated that peel strength decreases with increasing oligomer content and UV-dose, while holding power increases. The gel fractions sharply increased after UV irradiation and then remain constant with prolonged UV exposure. From peel-off test, sample S70 (70% oligomer content) shows the best peelability and removability without remaining any mark or adhesive material on the test substrate than S50 (50% oligomer content) and S60 (60% oligomer content). Sample S70 also showed a surface energy lower than $26mJ/m^2$ and a transmittance higher than 95% at UV-dose 1857 and $2270mJ/cm^2$ which met the required properties for protective film application.

• Korean Journal of Environmental Agriculture
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• v.19 no.4
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• pp.309-313
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• 2000

To investigate the effects of different UV-B levels on growth and biochemical defense response in plants, cucumber plants were subjected to three levels of biologically effective ultraviolet-B $(UV-B_{BE})$ radiation [daily dose: 0.03 (No), 6.40 (Low) and $11.30\;(High)\;kJ{\cdot}m^{-2}$, $UV-B_{BE}$] in the growth chambers for 3 weeks during the early growth period. Enhanced UV-B radiation drastically decreased both dry weight and leaf area of cucumber. With increasing UV-B intensity, chlorophyll content was decreased, however the level of malondialdehyde was highly increased linearly. Total contents of ascorbic acid and glutathione were tended to increase by UV-B, while the ratios of dehydroascorbate/ascorbate and oxidized glutathione/reduced glutathione were significantly increased with increasing UV-B intensity in cucumber. All the enzyme activities investigated (superoxide dismutase, ascorbate peroxidase, dehydroascorbate reductase, guaiacol peroxidase etc.) in cucumber were increased by the UV-B enhancement. These results suggested that enhanced UV-B irradiation caused photooxidative stress in cucumber plant and resulted in significant reduction in plant growth. Biochemical protection responses might be activated to prevent the leaves from damaging effects of oxidative stress generated by UV-B irradiation.