• Polymer(Korea)
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• v.26 no.2
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• pp.209-217
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• 2002

We studied the mechanism of orientation of polyimide molecules which were irradiated by polarized UU (PUV) using polarized Fourier transform infrared (FT-IR) spectroscopy and ultraviolet (UV) spectroscopy, According to the measured UV spectra, we found PI films mainly absorb UV light less than 350 nm wavelength, therefore, UV light less than 360 nm induces photochemical reaction of PI. PUV irradiation of PI films caused decrease of all peak intensities in the FT-IR spectra. except the newly formed broad peak at $3244 cm^{-1}$, due to degradation of the PI molecules. The remaining PI molecules after photo-degradation showed predominantly perpendicular molecular orientation to the irradiated PUV polarization direction, due to the preferential degradation of PI molecules parallel to irradiated PUV polarization direction. However the rubbing of PI films induced reorientation of the PI molecules parallel to the rubbing direction. We also investigated the alignment of the liquid crystal by rubbing or PUV irradiation. Liquid crystals align perpendicular to the PUV polarization direction and parallel to the rubbing direction.

• 대한치과보철학회:학술대회논문집
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• 1997.11a
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• pp.52-52
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• 1997

• Journal of the Society of Cosmetic Scientists of Korea
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• v.26 no.1
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• pp.41-58
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• 2000

Recently the harmfulness of W radiation is in creasing due to encironmental pollution. Environmental population may also play a role in global decrease of ozone layer, A major consequence of ozone depletion is increase in solar ultra violet radiation received at the earth's surface excessive exposure to W radiation cause a lot of problems in our skin. Plant extract that possess antioxidative activities has been reported to retard the oxidation process in product to which they have been added. Plant are alived under solar light. So it is expect the plants have so many protection mechanisms and UV absorbent ingredients against ultra violet radiation such as UVB, UVA. Plant extract which were flavonoids, alkaloids and others could be transformed into UV absorber by chemical modification. Therefore with the aim of finding alternative natural absorber that can safely be used in cosmetic, we have screened various extract for their UV absorbent effect. Thus, the cosmetic safety against human skin, antimicrobial effects and others could be improved by using the silicon.

• Proceedings of the SCSK Conference
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• 1996.07a
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• pp.10-14
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• 1996

최근 오존층의 파괴로 인한 지구 자외선량의 증가로 피부암 및 광노화의 발생가능성이 증가되고있다. 광노화의 주요한 현상중의 하나는 탄력섬유상 물질이 축적되는 일광탄력 섬유증이다. 자외선은 탄력소 유전자의 전사과정증가를 유도하며 결국 비정상적인 탄력소의 증가를 유발한다는 보고가 있다. 본 연구에서는 피부 섬유아세포 및 각질형성세포를 배양하여 자외선이 탄력소 유전자발현에 미치는 영향 및 전사조절인자에 미치는 영향을 알아보고자 하였다. 피부섬유아세포에 UVB를 30mJ-200J/m 조사하여 nothern blotting한 결과 UV양이 증가함에 따라 탄력소 전사물이 증가되었고, 1001/$m^2$ 에서 최대의 증가를 보였다. 탄력소 promoter와 CAT을 접합시킨 pEP62 vector을 섬유아세포에 형질전환 시키고 UV에 의한 Promoter 활성을 본 결과 UV조사량이 증가할수록 활성이 증가되었고 200J/$m^2$ 에서 대조군에 비해 5배의 활성 증가를 보였다. 이 system에 광노화 억제물질로 알려진 retinoid를 5 $\times$ $10^{-6}$M처리하였을 때 UV에 의한 탄력소 promoter활성을 약 1/3로 감소시켰다. 각질 형성세포에서 UVB에 의한 transcription factor의 활성을 mobility shift assay에 의해 조사한 결과 AP-1 및 NFkB가 활성화됨을 볼 수 있었다.

• Journal of Life Science
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• v.20 no.1
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• pp.27-32
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• 2010

Ultraviolet-B (UVB) radiation induces the formation of reactive oxygen species (ROS) and depletes stores of cellular antioxidants. Fucoidan, polysaccharides containing L-fucose and sulfate ester groups, are constituents of brown algae. In this study, the protective effects of fucoidan on UVB-induced oxidative stress in cultured human skin fibroblast HS68 cells were assessed. Pretreatment with fucoidan significantly reduced malondialdehyde (MDA) content in a dose-dependent manner. With fucoidan pretreatment at a dose of $100\;{\mu}g/ml$, the level of intracellular glutathione was increased by 21.5%, compared to UVB irradiation alone. Fucoidan significantly reduced UVB-induced ROS generation by 40.1% and 68.4% at 10 and $100\;{\mu}g/ml$, respectively, compared to UVB irradiation alone. The positive staining rates of senescence-associated $\beta$-galactosidase were reduced by 23.1% and 16.4% with 10 and $100\;{\mu}g/ml$ of fucoidan, compared to UVB irradiation alone. Fucoidan may exert a photoprotective effect against UVB radiation-induced oxidative stress.

• The Korean Journal of Pharmacology
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• v.29 no.1
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• pp.65-72
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• 1993

Ultraviolet light radiation (UVR) did not affect resting tension of isolated thoracic aortae of rats. In aortic rings contracted with phenylephrine, however, UVR produced contractile and relaxant responses in preparations with and without endothelium, respectively. The contractile response was dependent upon the duration $(10{\sim}320\;sec)$ of irradiation, while the relaxation was not. UVR-induced contractions in endothelium-intact rings were significantly potentiated by increasing the concentrations of phenylephrine from $10^{-7}M$ to $10^{-5}M$, and also by addition of $10^{-6}M$ acetylcholine, $10^{-7}M$ isoproterenol and $3.5{\times}10^{-8}M$ nitroglycerine. However, addition of $10^{-6}M$ phentolamine, or $10^{-7}M$ to $10^{-6}M$ LY83583 inhibited the contraction or reversed the contraction to a relaxation. In endothelium-removed preparations the UVR-induced relaxation was attenuated by increasing concentractions of phenylephrine, and by addition of isoproterenol, nitroglycerin, phentolamine or LY83583. These results suggest that UVR produces contractile and relaxant responses in rat thoracic aortae with and without endothelium, respectively, and that the contractile effect results from the inhibition of endothelium-derived relaxing factor (EDRF) release by UVR the inhibition of and/or is in part re-lated to some endothelium-derived contractile factors (EDCFs).

• The Korean Journal of Zoology
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• v.25 no.2
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• pp.55-62
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• 1982

DNA synthesis, unscheduled DNA synthesis, excision of pyrimidine dimers and phtoreactivation were determined in UV-irradiated differentiating muscle cells at various times of primary culture of 12 day chick embryos and results obtained were as follows. The rates of UV-induced unscheduled DNA synthesis were increased as increase of UV dose. And the rates were gradually decreased as the increase of time after culture, but at higher doses the decreasing tendency was remarkable. The patterns of DNA replication were changed drastically as a function of time so that in the seven day cultures the rate of $^3$H-thymidine incorporation was found to be 0.2% of the original activity. The pattern of inhibition of DNA replication by UV damage demonstrated that in cells of earlier stages there were no remarkable changes, but in cells of later stages there was significant fluctuation. Photoreactivation and the excision of pyrimidine dimer in the one day cultures showed that photoreactivation occurred immediately after UV-irradiation, but excision of pyrimidine dimer was gradually and slowly occurred. These results indicate that the differentiation of embryonic muscle cells accompanies the gradual reduction of DNA replication and unscheduled DNA synthesis, and that the photoreactivation is rapid process compared to excision repair.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.47 no.4
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• pp.289-296
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• 2021

In this study, 27 inorganic sunscreens and 23 sunscreens for children were collected to investigate the use and incorporation of 17 types of sunscreen agents, 13 types of preservatives, and 5 types of heavy metals. As a result, sunscreen agents were detected in the order of titanium dioxide (41 cases), zinc oxide (29 cases), bis-ethylhexyloxyphenyltriazine (10 cases), ethylhexyl salicylate (8 cases), and ethylhexylmethoxynamate (8 cases), and preservatives were detected in order of phenoxyethanol (6 cases), benzoic acid (1 case), and dihydroacetic acid(1 case). All of the identified sunscreen agents were suitable for labeling, but phenoxyethanol, a preservative component other than labeling, was detected at a concentration of 0.1%. Heavy metals such as lead, cadmium, arsenic, antimony, and nickel were not detected or were detected at various concentrations of less than 3.6 ㎍/g. All the detected UV filters, preservatives, and heavy metals were less than the allowed maximum amount stipulated by the Regulations on Cosmetic Safety Standards in Korea.

• Journal of the Korean Applied Science and Technology
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• v.34 no.2
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• pp.349-356
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• 2017

OH radical generation is one of the common method to evaluate photocatalytic activity. In many of previous studies, only the UV(Ultraviolet) light was applied to test photocatalytic ability of $TiO_2$ nanotubes by studying probe compound(4-Chlorobenzoic acid) concentration change in solution. Also, $TiO_2$ nanotubes were found to show some electrochemical characteristics when the flow of electric current was applied. In this study, the flow of electric current and UV light were applied at the same time to determine whether electrochemical characteristics of $TiO_2$ nanotube plate can give synergetic effect on the photocatalytic activity. $TiO_2$ nanotube was grown on Ti by anodic oxidation to create $TiO_2$ nanotube plate which can be used as a photocatalyst and a electrode that can undergo AOP(Advanced Oxidation Process) for water treatment. Probe compound solution was prepared using 4-chlorobenzoic acid and $H_2O$ as a solvent. NaCl was added to give conductivity to work as electrolyte. As a result, enough level of electric current flow was found to give synergetic photocatalytic effect which can be used for efficient AOP water treatment method.

• Food Science and Preservation
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• v.19 no.1
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• pp.47-53
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• 2012

UV light irradiation is known to give beneficial effects on fresh produce preservation. A container system equipped with UV-LED was fabricated for storing cherry tomatoes under computer-controlled conditions of intermittent on-off cycles (1 hour on/1 hour off). Wavelength (365 and 405 nm) and physical location of the LED (2 and 5 cm above fruit) were studied as variables affecting the respiration, ethylene production and quality preservation of the fruits at 10 and $20^{\circ}C$. 365 nm wavelength gave much higher radiation intensity than 405 nm, and intensity on surface decreased in inverse proportion to square of distance from LED. When compared to non-irradiated control, UV-LED irradiation decreased the respiration by 5-10% at $10^{\circ}C$ while there was no obvious effect at $20^{\circ}C$. Ethylene production was reduced when the fruits were placed at 5 cm distance, while there was no significant difference from control at 2 cm location. The reduction of ethylene production at 5 cm was more pronounced at $20^{\circ}C$. UV-LED irradiation was shown to have delayed increase or lower concentration in carotenoids compared to control treatment. Any negative effect of UV-LED irradiation on ascorbic acid content and firmness was not observed.