• Journal of Photoscience
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• 제9권2호
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• pp.466-469
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• 2002

An experiment has been conducted to measure the impact of UV radiation sensitivity on dermatophytes (Microsporum boullardii) by different UV radiation exposure time interval (1 min, 2 min 5 min, 10 min and 20 min) in degradation of keratin (Feather) in growth promoting substances of protein, cysteine, cystine and methionine from 7 to 28 days of incubation period. Mutant strain caused maximum weight loss with 1 minutes of UV radiation exposure at 21 day and mutant strain became immune in sensitivity at 14 days for decomposition of feathers. Maximum protein caused at 21st days with 20 minutes U.V radiation exposure and immune sensitivity had deducted with other UV radiation exposure time. On 28 days, mutant strains became immune with all exposure times, Whereas maximum methionine caused at 21st days with 20 minutes UV radiation exposure. Maximum cysteine caused at $14^{th}$ day with 5 minutes UV radiation exposure and mutant strain showed immune response at all time periods. Cystine production was also followed by cysteine at 21 day and also showed complete immune response with 1 and 2 minutes UV radiation exposure at7 and 14 days. Thus mutant strain of Microspornm boullardii can be used as a biotechnological tool for production of growth promoting substances.

• 공업화학
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• 제20권5호
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• pp.511-516
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• 2009

폴리올레핀 복합소재의 UV 광열화 특성을 조사하였다. 열중량분석 결과, 3종의 폴리올레핀 복합소재는 서로 다른 talc 함유량을 가지고 있음을 확인하였다. SAE J1960 규격에 따라 UV 조사된 폴리올레핀 복합소재의 기계적 거동을 관찰하기 위해 인장시험 및 아이조드 충격 시험을 수행하였다. UV 노출 시간이 증가함에 따라 연신율과 저온 충격강도는 급격히 감소하였다. 이는 UV 광열화에 의한 폴리머 분자체인의 절단 및 얽힘 밀도 감소에 따른 탄성력의 감소에 기인한 것으로 보인다. 전자주사현미경 관찰을 통하여 UV 조사 후 표면상에 크랙이나 표면손상은 존재하지 않았지만, UV 노출에 따른 추가적인 talc 입자의 표면 노출을 관찰할 수 있었다. 이러한 talc 입자의 표면 노출은 폴리올레핀 복합소재의 변색 원인으로 추정된다. 적외선분광분석을 통하여, UV 조사된 폴리올레핀 복합소재의 표면상에 광열화가 진행되었음을 확인하였다.

• 한국정밀공학회지
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• 제34권1호
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• pp.65-72
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• 2017

The goal of this paper is to investigate the effects of out-of-plane deposition angle on product characteristics of a UV photo-curing process. Specimens are manufactured from a commercialized UV photo-curing machine, the NOBEL V1.0. The influence of the out-of-plane deposition angle of the specimen on surface characteristics, including morphology of the sloped surface, pick-to-pick distance of convex region, and roughness of the sloped surface, is examined via the observation of the sloped surface. In addition, the influence of the radius of curvature of the specimen on the surface roughness of the sloped surface is evaluated. The effects of the out-of-plane deposition angle on impact strength of specimens are investigated via Izod impact experiments. Finally, we discuss the influence of the out-of-plane deposition angle on failure characteristics of specimens for impact loads.

• 청정기술
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• 제16권4호
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• pp.245-253
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• 2010

대구경 강관 표면 보호를 위해 사용되는 필라멘트 와인딩 공정에 불포화 폴리에스터 (unsaturated polyester: UP)를 이용한 자외선 (ultraviolet) 경화 방법을 적용하고자, UP를 이용한 최적의 UV 경화 조건을 찾아보았다. 기존의 유기계 과산화물을 개시제로 사용한 열경화 방법에서는 개시제의 불안정성, 휘발성 유기물 발생, 열에 약한 대상물질의 변형 등 문제점이 발생하므로 이에 대한 개선책으로 UV 경화방법을 시도하였다. UV 경화에 사용되는 다양한 개시제 중에서 비교적 침투력이 높아서 두꺼운 고분자 층 형성이 가능한 개시제 2 종(Irgacure 819 및 Darocure 1173)을 선정하여 이들의 조합비율에 따라 경화된 UP 고분자에 대한 열역학적, 기계적 물성을 비교 분석하여 우수한 경화조건 (개시제 함량 1.5 phr, 혼합 비율 1:1.2, UV 램프로는 갈륨램프)을 찾아내었다. 또한 UP 광경화수지의 경도, 충격강도, 굴곡강도 향상을 위해 유리섬유를 수지 내에 적층하여 복합재료를 제조하고 이들의 특성을 비교한 결과 충격강도가 매우 향상되었다.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제3권3호
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• pp.197-201
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• 1999

The growth of two phytoplanktons was studied in a natural environment and in the laboratory under artificial radiation conditions in the presence or absence of UV radiation. The effect of an elevated temperature on the two phytoplanktons was also examined. UV radiation resulted in a decrease in the growth of the two phytoplanktons ; P. micans was more affected by UV than S. costatum. Four hours of UV radiation decreased the motility of S. costatum and P. micans by 20% and 40%, respectively. Accordingly, an elevated temperature and UV radiation decreased the growth rate of the two phytoplanktons investigated.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
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• pp.106-109
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• 2001

In this paper, we have investigated the degradation of shed materials of outdoor insulators by UV-radiation by using corona-charging and XPS analysis. The accumulated charges on polymeric surface having intrinsic hydrophobic property have a negative impact on retaining its hydrophobicity. Therefore, shorter decay times of surface charges are preferred. The surface voltage decay on UV-treated silicone rubber and EPDM show a different decay trend with UV treated time. From the XPS analysis, the oxidized groups of silica-like structure in silicone rubber increase with UV treatment time. For EPDM, the oxidized carbon groups of C=O, O=C-O increase as elapse of UV radiation time. These oxidized surface for each material have different electrostatic characteristics, so deposited charges may be expected to have different impacts on their surface hydrophobicity. The degradation mechanism based on our results is discussed.

• 전기전자학회논문지
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• 제17권4호
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• pp.531-536
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• 2013

The impact of UV irradiation process on the AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistor was investigated. Due to the high intensity UV irradiation before the gate dielectric deposition, the conductivity of AlGaN/GaN structure and the drain saturation current of the transistor increased by about 10 %. However, the pinch off characteristics of transistor was severely deformed by the process. By comparing the electrical characteristics of the transistors, it was proposed that the high intensity UV irradiation formed a sub-channel under the two dimensional electron gas of AlGaN/GaN structure even without additional impurity injection.

• 한국기계가공학회지
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• 제9권3호
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• pp.56-61
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• 2010

Recently, UV pulse laser is widely used in micro machining of the research, development and industry field of IT, NT and BT products because the laser short wavelength provides not only micro drilling, micro cutting and micro grooving which has a very fine line width, but also high absorption coefficient which allows a lot of type of materials to be machined more easily. To analyze the dynamic deformation during a very short processing time, which is nearly about several tens nanoseconds, the commercial Finite Element Analysis (FEA) code, LS-DYNA 3D, was employed for the computitional simulation of the UV laser micro machining behavior for thin copper material in this paper. A finite element model considering high strain rate effect is especially suggested to investigate the micro phenomena which are only dominated by mechanically pressure impact in disregard of thermally heat transfer. From these computational results, some of dynamic deformation behaviors such as dent deformation shapes, strains and stresses distributions were observed and compared with previous experimental works. These will help us to understand micro interaction between UV laser beam and material.

• 한국인쇄학회지
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• 제25권1호
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• pp.95-107
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• 2007

This study starts to find a way out, experiment and apply commercial UV coatings to the cap closures. The cap closures is made form coating and succeeding deformation process. It is coated with several printing layers, printing and over print varnish coating. Then it pressed in three steps of press called 'deep-drawing'. In this study, two kinds of coating was designed and accomplished in the base of the same manufacturing and environment conditions. Consequently, UV curable ink have adequate performance in this experiment (T-bending, Erichsen Test), but it were experienced several damages in this experiments (web-bending, impact test). They were not cured enough to endure the friction and a unique shape of serial cracks were appeared.

• 한국환경보건학회지
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• 제33권5호
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• pp.441-450
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• 2007

본 연구는 humic acid 및 bromide를 함유한 상수 원수에 오존 처리를 수행함에 있어 수질 특성 및 공정조건에 따른 bromate 및 formaldehyde 의 생성을 고찰하였다 . 회분식 실험장치를 이용하여 오존의 주입농도, DOC 농도, bromide 농도, pH, 알칼리도 및 반응 시간을 변화시키면서 오존처리 시 생성되는 대표적인 부산물인 bromate 및 formaldehyde의 거동을 파악하였다. 본 연구에서 검토된 영향 인자 중 수중의 pH조건은 bromate 및 formaldehyde의 생성에 가장 중요한 인자로 나타났다. DOC(dissolved organic carbon) 농도가 증가할수록 bromate 생성은 감소하였고 formaldehyde 의 생성은 증가하였다. 오존처리를 통해 UV254 는 효율적으로 감소되었고, UV254의 감소율 및 오존 농도는 선형 관계를 나타냈다.