• Current Optics and Photonics
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• 제6권2호
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• pp.202-211
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• 2022

In the pasteurization of escalator handrails using ultraviolet (UV) sterilizers, a combination of light distribution and escalator speed has priority over other important factors. Furthermore, since part of the escalator handrail has a curved structure, proper design is needed to improve the sterilization rate on the surfaces touched by users. In this paper, two types of sterilizers satisfying these conditions are manufactured with 275-nm UV-C LEDs, after modeling the three-dimensional (3D) structure of an escalator handrail and simulating optical distributions of UV-C irradiation on the handrail's surface according to light-emitting diode (LED) positions and reflector variations in the sterilizers. Pasteurization experiments with the UV-C LED sterilizers are conducted on six types of gram-positive and gram-negative bacteria, with exposure times of 0.2, 5, and 15 s at an actual installation distance of 20 mm. The sterilization rates for the gram-positive bacteria are 10.63% to 27.94% at 0.2 s, 89.44% to 96.30% at 5 s, and 99.64% to 99.88% at 15 s. Those for the gram-negative bacteria are 57.70% to 77.63% at 0.2 s, 98.90% to 99.49% at 5 s, and 99.88% to 99.99% at 15 s. The power consumption of the UV-C LED sterilizer is about 8 W, which can be supplied by a self-generation module instead of an external power supply.

• 한국염색가공학회지
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• 제23권3호
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• pp.155-162
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• 2011

para-Aramid has limited dyeability because of its highly crystalline structure and compactness. To improve the dyeability of the para-aramid to reactive dyes of bright color in deep shade, the fabrics were photografted under continuous UV irradiation with dimethylaminopropyl methacrylamide and 4-benzoyl benzoic acid as a monomer and a hydrogen -abstractable photoinitiator respectively. A UV energy of 35J/$cm^2$ and a photoinitiator concentration of ten percent or more with respect to the monomer in the formulation was required for optimal photografting. Grafting yield increased with higher monomer application level. Surface analysis indicated significant alterations in the atomic composition of the photografted fabric surface and the fabric surface was covered with the grafted polymers. While the pristine para-aramid fabrics showed no appreciable dyeability to the ${\alpha}$-bromoacrylamide reactive dyes, the grafted para-aramid fabrics enhanced the dyeability to the reactive dyes substantially. In case of C.I. Reactive Blue 50, a K/S value of 8.7 can be obtained with the grafted para-aramid fabrics with a grafting yield of 2.3 %. Also the color fastness properties of the dyed fabrics was excellent in the conditions of washing, rubbing and light irradiation.

• Environmental Engineering Research
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• 제19권3호
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• pp.215-221
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• 2014

Nano-sized $TiO_2$ particles were produced by a premixed flame aerosol reactor, and they were immobilized on a mesh-type substrate in form of particulate film. The reactor made it possible maintaining the original particulate characteristics determined in the flame synthetic process. The particulate morphology and crystalline phase were not changed until the particulate were finally coated on the substrate, which resulted in the better performance of the photocatalytic conversion of the volatile organic compounds (VOCs) in the ultraviolet $(UV)-TiO_2$ system. In the flame aerosol reactor, the various specific surface areas and the anatase weight fractions of the synthesized particles were obtained by manipulating the parameters in the combustion process. The performance of the $TiO_2$ particulate films was evaluated for the destruction of the VOCs under the various UV irradiation conditions. The decomposition rates of benzene and formaldehyde under the irradiation of UV-C of 254 nm in wavelength were evaluated to check the performance of $TiO_2$ film layer to be applied in air quality control system.

• Biomolecules & Therapeutics
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• 제18권3호
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• pp.300-307
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• 2010

Photosensitized peroxidation of membrane lipids has been implicated in skin pathologies such as phototoxicity and premature aging. We have previously reported that syriacusin compounds isolated from Hibiscus Syriacus inhibited lipid peroxidation. Here, we investigated whether syriacusins could be effective inhibitor to skin aging using ultraviolet-irradiated human dermal fibroblast cells (HDFCs). Syriacusins A, B, and C inhibit the activity of human neutrophil elastase (HNE), a serine protease to degrade extracellular matrix (ECM) proteins including elastin, with $IC_{50}s$ of 8.0, 5.2, and $6.1\;{\mu}M$, respectively. No changes in cell viability were detected by syriacusins A and B in UV-B ($10\;mJ/cm^2$) irradiated HDFCs. Matrix metallo-proteinase (MMP)-1 expression in HDFCs was increased by UV-B irradiation. MMP-1 expression in UV-B irradiated HDFCs was decreased by $10\;{\mu}M$ and $20\;{\mu}M$ syriacusin A to 50% and 20% of untreated control, respectively. Syriacusin B treated with $20\;{\mu}M$ reduced MMP-1 expression in UV-B irradiated HDFCs to 60% of untreated control. Syriacusin A also inhibited MMP-2 expression accompanying the increase of type-I pro-collagen in UV-B irradiated HDFCs. These results demonstrate that syriacusin A could be a more effective compound to inhibit skin aging caused by UV irradiation. It suggests that syriacusins A and B might be developed as possible agents to treat or prevent skin aging.

• Elastomers and Composites
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• 제45권1호
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• pp.25-31
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• 2010

우리는 탄소 전구체로 활성탄 (AC), 활성탄 섬유 (ACF)와 탄소나노튜브 (MWCNT)와 티타늄 전구체로써 TNB를 사용하여 탄소-$TiO_2$ 복합체를 제조하였으며, 이들의 특성을 SEM, TEM, BET, XRD와 EDX를 이용하여 분석하였다. 그리고 이들의 광촉매 활성은 UV 램프 조사에서 일정한 농도의 MB 용액을 이용하여 측정하였다. UV 조사한 후에 MB의 농도는 UV-vis 분광광도기를 이용하여 측정하였다.

• 한국산학기술학회논문지
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• 제11권5호
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• pp.1760-1767
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• 2010

FAT복합체는 TOS ($TiOSO_4{\cdot}xH_2O$)를 사용하여 솔-겔 방법으로 제조한다. 시료들은 SEM, 비표면적, XRD 및 EDX를 사용하여 분석하였다. SEM결과로서 Fe 와 $TiO_2$ 입자가 AC 표면에 분포하고 있다. XRD 결과에서 Fe-AC/$TiO_2$ 복합체는 다 anatase결정상을 하고 있다. 그리고 EDX 결과에서 C, O, Ti 및 Fe 원소가 Fe-AC/$TiO_2$ 복합체에 다 존재하고 있다. 복합체의 광촉매 활성은 가시광선과 UV광선을 사용하고 메틸렌불루(MB)의 분해 효과에 의해 측정한다. Fe-AC/$TiO_2$ 복합체는 강한 가시광선 조사에서 우수한 광촉매 효과가 나타난다. AC/$TiO_2$ 복합체에 있는 소량 존재하는 Fe 원소가 그들의 광촉매 활성을 강화할 수 있다.

• Journal of Microbiology and Biotechnology
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• 제13권4호
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• pp.544-551
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• 2003

Interactive effects of UV-B and Cd on growth, pigment, photosynthesis, and lipid peroxidation have been studied in Anabaena, Microcystis, and Nostoc; all the tested cyanobacteria showed differential sensitivity to different dosage of UV-B and Cd alone as well as in combination. Phycocyanin was severely affected by UV-B and Cd by all the strains; the degree of pigment bleaching was most pronounced in Anabaena followed by Microcystis and Nostoc. $UV-B_2+Cd_2$ produced nearly 83, 78, and 65% inhibition of phycocyanin in Anabaena, Microcystis, and Nostoc, respectively. The above treatment also significantly decreased the contents of Chl ${\alpha}$ and carotenoid. Presence of capsule in Microcystis protected the phycocyanin bleaching as compared to decapsulated cells. Laboratory-grown Microcystis revealed about 75 and 80% inhibition, following $UV-B_2+Cd_2$ treatment, respectively. in capsulated and decapsulated cells. Damage caused by Cd was more pronounced than UV-B. Inhibition of photosynthesis did occur in all the test strains, being maximum in Anabaena. PS II was the most sensitive component of the electron transport chain, showing 84, 80, and 70% inhibition in Anabaena, Microcystis, and Nostoc, respectively. As compared to control, significant lipid peroxidation (6.5-fold higher) was observed in Anabaena with $UV-B_2+Cd_2$, $^{14}C-uptake$ was more susceptible to Cd and Uv-B than oxygen-evolution. Approximately 84, 80, and 76% inhibition of $^{14}C-uptake$ was observed in Anabaena, Microcystis, and Nostoc, respectively. Similarly, $UV-B_2+Cd_2$ inhibited APT content of Anabaena by 87%. This ,study suggests that inhibition of carbon fixation was due to decreased ATP content of the test cyanobacteria by UV-B+Cd, where Anabaena was the most sensitive and Nostoc the most tolerant.

• 한국응용과학기술학회지
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• 제17권4호
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• pp.273-278
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• 2000

Cellulose tosylate(CT) was prepared by reaction of cellulose with p- toluenesulfonylchloride in DMAc/LiCl homogeneous system. In order to study a reversible photoisomerization of disperse red 1(DR-1) attached on natural polymer, cellulose tosylate containing DR-1(DR-1/CT adduct) was prepared at $110^{\circ}C$ in DMAc, and the changes of UV/Vis spectra of its solutions and thick film were investigated by alternate irradiation technique. Form the UV/Vis spectra of DR-1/CT adduct dissolved in cosolvents, such as DMAc, DMAc/THF, DMAc/benzene, and DMAc/chloroform and irradiated with 360 nm and 450 nm ligths, we found out changes of UV/Vis spectra were reversible in all solvents systems and we found out changes of UV/Vis spectra were reversible at thick film, also.

• 한국미생물·생명공학회지
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• 제8권2호
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• pp.87-92
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• 1980

선정균을 장기간 보다 안전하게 관리하고 균의 성질을 개선하기 위하여 실험한 결과는 다음과 같다. 1) 선정균은 대체로 0~5$^{\circ}C$에서 soil 배지에 보존하는 것이 좋았으며 보존기간 10개월까지는 산생성력에 큰 변화를 보이지 않았다. 2) 선정균 M-315는 강산성지에 계대배양하므로서 산생성능이 약간 향상되였으며 종균으로는 포자형성배지에 7~10일간 배양한 균의 포자로 접종하는 것이 좋았다. 3) 선정균에 자외선을 조사시킨 결과 형태적으로 변화된 변이주 109주을 분리하였고 그 중 산생성력이 3.2% 향상된 변이주 M-812를 얻었다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 1999년도 Pre-symposium of the 10th ISWPC Recent Advances in Paper Science and Technology
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• pp.296-301
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• 1999

Different papers such as toilet and towel tissue, newsprint and copy paper made from reclaimed fibres were characterized using UV-VIS reflectance and fluorescence spectroscopy. The emission properties of the extracts of the papers were also evaluated. Photochemical irradiation at ambient temperatures, and thermal aging of the copy papers at 105$^{\circ}C$ and 150$^{\circ}C$ were performed. Post-colour numbers (PC) were calculated from the reflectance values measured from the corresponding UV-VIS reflectance spectra. Light absorption coefficient spectra were calculated before and after irradiation, and the changes in absorption coefficient were related to the content of chromophores in the papers. Photochemical and thermal discolouration of the copy papers, similar to that of virgin fibres, was readily observed. The influence of changes in the concentrations of fluorescent brightening agents and dyes on the spectral properties was also assessed. Photostabilization studies of the copy papers were performed with the use of polymer additives polyethylene glycol (PEG) and polytetrahydrofuran (PTHF).