• Analytical Science and Technology
• /
• v.24 no.5
• /
• pp.336-344
• /
• 2011

The study attempted to find out any effect to prevent photo aging of epoxy resin used for conservation by way of adding UV stabilizer, one of plastic additives. Specimens were made by adding HALS and UVA UV stabilizer as each concentration to 3 kinds of epoxy resin, which are most frequently used for artifacts joining and restoration process, and aging effects were investigated through Color change, SEM, contact angle, FTIR analysis during UV aging experiments. Last, usage suitability was checked when UV stabilizer was added through Universal Tensile strength tester. In result, it is impossible to prevent decomposition of chemical structure in spite of adding UV stabilizer but in the case of epoxy A and R, it is believed that photo aging such as yellowing or crack can be minimized without giving a big influence to adhesive strength of epoxy resin through adding less than 0.1% of UVA. It is expected that above will solve photo aging problem of epoxy resin used for joining and restoration of artifacts and will extend its life as joining and restoration materials.

• Journal of the Korean Vacuum Society
• /
• v.16 no.1
• /
• pp.23-26
• /
• 2007

The effect of annealing parameters on the micro-structure of Mg alloy AZ91D was investigated by photo reflectance spectroscopy and electron microscopy. The reflectance spectra show that carbon defects exist in the annealed sample. From the electron microscopy, it is found that the oxide layer on the annealed sample has better uniformity.

• Journal of the Korean Magnetics Society
• /
• v.13 no.3
• /
• pp.103-108
• /
• 2003

A micromagnetic model and a Stoner-Wohlfarth model are used to analyze the effect of demagnetization field in patterned permalloy films. Permalloy films of 20 $\mu\textrm{m}$${\times}$(40 $\mu\textrm{m}$∼200 $\mu\textrm{m}$) are fabricated by DC magnetron sputtering and photo lithography. Measured magnetoresistance data of patterned permalloy films are compared with simulation results. The micromagnetic model gives a better agreement with the measured MR data than the Stoner-Wohlfarth model. Based on the simulation results, we propose a revised approximation formula for dernagnetization field in Stoner- Wohlfarth model for a few fm patterned magnetic films.

• Korean Journal of Veterinary Research
• /
• v.46 no.3
• /
• pp.279-284
• /
• 2006

Photo-catalytic products have been widely used at home and hospital to prevent bacteria, virus and fungus. Activities of anti-bacteria, anti-viruses and anti-fungi are based upon direct contact of crystals and particles of titanium dioxide with pathogens, into which titanium is catalyzed by photo. Those antimicrobial activities of the photo-catalytic titanium dioxide have been proved in vitro. However, in vivo tests of those activities have not been carried out on dog skin. Aim of this study was to evaluate the antimicrobial activities of the catalytic titanium dioxide in vivo. Ten beagle dogs were divided into two groups. One group was sprayed with 10ml of titanium dioxide(1 mg/ml) whereas the other was not. The treated dogs were exposed under the sunlight for 120 min. A set of three hairs was taken 15, 30, 60 and 120 min after the exposure and the bacteria contaminated in hairs were amplified in, Muller Hilton broth at $35^{\circ}C{\pm}1$ for 3 h. The supernatant of the bacterial culture was diluted 1 : 10 in phosphafe-buffered saline. One milliliter of the diluents was transferred into triphenyltetrazolium medium(TTC) and incubated at $35^{\circ}C{\pm}1$ for 2 days. The number of bacteria was counted. The number of bacteria colonies was decreased compared to control group. To further investigate the longevity effect of titanium dioxide, the dogs were kept in indoor without sun light for 6 and 12 h, 1, 2, 3, 7, 14 days after exposure of the chemical during each 15, 30, 60 min. The number of bacteria colony in 1ml was counted. The number of bacterial colonies was decreased. Treated group is exposured by sun light during 15 min, the longevity effect of titanium dioxide is continued by 1 week. Treated group is exposured by sun light during 30, 60 min, the longevity effect of titanium dioxide is continued over 2 weeks. These data indicated that the photo-catalytic titanium dioxide may be used for prevent bacteria on dog skin.

• The Korean Journal of Food And Nutrition
• /
• v.30 no.2
• /
• pp.211-217
• /
• 2017

In the present study, we investigated the protective effect of various grain methanolic extracts against UVB-induced photo-aging in human skin fibroblasts. Various grain methanolic extracts were evaluated for their antioxidant compounds and activities. 2,2-Ddiphenyl-1-picryhydrazyl radical (DPPH) and ABTS 2,2-azino-bris-(3-ethylbenzoth iazoline-6-sulphonic acid) radical cation scavenging activities have been used to measure the relative antioxidant activities of extracts from grains. The content of total polyphenolics in the extracts were evaluated using spectrophotometric methods. Human skin fibroblast (Hs68) cells were pretreated with various grain methanolic extracts ($25{\mu}g/mL$). Skin toxicity was simulated by exposing the cells to UVB ($30mJ/cm^2$) irradiation. In response to the UVB-irradiation, an increased amount of matrix metallo-proteinases (MMPs) release was observed, whereas pretreatment of various grain methanolic extracts significantly inhibited the production of MMP-1 in Hs68 cells. We also found that pretreatment of the extracts significantly decreased UVB-induced reactive oxygen species and significantly increased total collagen content in Hs68 cells. These results provide that grains could be regarded as a potential ingredient in natural cosmetics, used for UVB protection.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.38 no.4
• /
• pp.401-408
• /
• 2009

PME88 (gliadin-combined) melon superoxide dismutase (SOD) is known to promote the production of the body‘s own natural antioxidants including superoxide dismutase, catalase and glutathione peroxidase. In this study, we investigated the inhibitory effects of PME88 melonSOD on the ultraviolet-induced photo-aging by the evolution of minimal erythemal dose (MED), erythema quotation and spectrocolorimetric measurements of erythema. The analysis of the evolution of the MED showed a significant increase 28 days after the daily taken of the PME88 melonSOD. The analysis of the erythema quotation showed that on D29, for the dose 1.25 MED, erythema intensity is significantly higher for placebo group than for PME88 melonSOD group. At doses 0.64 MED$_{D14}$, 0.80 MED$_{D14}$ and 1 MED$_{D14}$ the value of parameter $a^*$ (the most sensitive to the colour changes bound to the variations of blood flow. It permits to assess the evolution of erythema) is significantly higher for placebo group. No significant difference has been observed between groups (PME88 melonSOD and placebo) on the evolution of the number and consistency of feces after 4 weeks of treatment. No intolerance has been observed during the 4 weeks of treatment. These results mean that PME88 melonSOD as a dietary supplement could be useful to attenuate ultraviolet-induced skin photo-aging.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.47 no.6
• /
• pp.6-11
• /
• 2010

Amount of power generated from solar photovoltaic can vary according to solar flux of sunlight due to nature of solar cell panel, and an angle that the sun and the surface of cell makes brings difference in amount of power generation. Solar flux is decided by location of surface of the Earth that is classified into longitude and latitude, but on the other hand, an angle that the sung and the surface of cell makes can be changed by changing the angle of a solar power generation device at the fixed location. A method of changing the angle of a solar power generation device as a measure for improving practical power generation efficiency. and studies about a solar tracking device for this are in active. This study conducted a research on a solar tracking system for improvement of solar power generation efficiency. A solar tracking system of this study is composed of a sensor part to confirm a location of the sun with a semiconductor photosensor using the photo conductive effect, and it analyzed output signal of a sensor by using microprocessor and it produced a control signal of driving part for tracking the sun. A solar power generator (25W) was produced to analyze performance of a solar tracking system and usefulness of a solar tracking device that was designed and produced in this study was confirmed through experiments.

• Korean Chemical Engineering Research
• /
• v.59 no.1
• /
• pp.112-117
• /
• 2021

In this study, a method of self-assembly of peptides based on irreversible covalent bonds was studied by mimicking a biological covalent bond, dityrosine bond. A tyrosine-rich short peptide monomer having the sequence of Tyr-Tyr-Leu-Tyr-Tyr (YYLYY) was selected to achieve a high-density of dityrosine bond. The peptide nanoparticles covalently self-assembled with dityrosine bonds were synthesized by one-step photo-crosslinking of a peptide using a ruthenium catalyst under visible light. The effect of the concentration of each component for the size of the peptide nanoparticle was studied using dynamic light scattering, UV-Vis spectroscopy, and transmission electron microscopy. As a result, the synthesis conditions for size of the peptide nanoparticles ranging from 130 nm to 350 nm were optimized.

• Food Science and Preservation
• /
• v.20 no.5
• /
• pp.684-690
• /
• 2013

The antioxidant and photoprotective effects of various extracts from the roots of Rumex crispus L. were evaluated. The concentrations ($IC_{50}$) of various extracts required to exert a 50% reducing effect on a DPPH radical were found to be 0.005~0.093 mg/mL. The ethyl acetate extract showed a more remarkable effect than the positive control ascorbic acid. The concentrations ($QC_{50}$) of the butanol and ethyl acetate extracts required to exert a 50% reducing effect on the singlet oxygen $^1O_2$ were found to be 0.464 and 0.365 mg/mL, respectively. Both extracts were also found to protect the in vitro biological system from the detrimental effect of a singlet oxygen $^1O_2$ on type II photosensitization in E. coli and genomic DNA. Among all the tested extracts, the ethyl acetate and butanol extracts contained higher amounts of total phenolic contents. The results suggest that our study may contribute to the development of new bioactive products with potential applications to the reduction of photo-produced oxidative stress involving reactive oxygen species in living organisms.

• Applied Biological Chemistry
• /
• v.43 no.2
• /
• pp.130-135
• /
• 2000

Photodegradation rate of flupyrazofos in aqueous solution were measured under various test conditions mainly following the guidelines of U.S. EPA and OECD. It was observed that the flupyrazofos was degraded by simple hydrolysis but not degraded by light in pure water. Using acetone as a known photosensitizer, the minimal concentration of acetone needed to photo-degrade the flupyrazofos in % and molar terms were 0.047% and 0.006, respectively. When treated with acetone, it was also found that the ringlet oxygen is a very effective photo oxidant in the degradation of flupyrazofos, but the effect of hydroxyl radical was not observed at the treatment level of hydroxyl radical, isopropylbenzene. In an actinometer experiment, quantum yield of flupyrazofos (0.4 ppm with 2% acetone) was $17.66{\times}10^{-5}$ and degradation rate and half-life were 0.038/hr and 18.2 hours, respectively.