• Title/Summary/Keyword: UV light

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Development of a Novel Micro-stereolithography Technology using UV Lamp and Optical Fiber (UV 램프와 광섬유를 이용한 새로운 개념의 마이크로 광 조형기술의 개발)

  • Choi, Ji-Soon;Lee, Seung-Pyo;Ko, Tae-Jo;Lee, In-Hwan
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.12 s.189
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    • pp.117-121
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    • 2006
  • Generally, micro-stereolithography technology uses laser and complex optical system as light source and light delivery system, respectively. In this research, a novel micro-stereolithography technology that uses UV lamp that is more economical than UV laser as light source and optical fiber that is simpler than previous light delivery system has been developed. Furthermore, precise control system that is composed of 3-axis linear stage and shutter has been used to fabricate truly three dimensional micro-structure. For confirming the feasibility of developed micro-stereolithography apparatus, the solidification experiments were conducted. The solidification widths and depths datum of photopolymer as varying scanning speed of the UV light have been obtained. Using developed apparatus, some micro structures were fabricated successfully.

Deterioration Mechanism of Paper According to Sizing and Beating (II) -Influences of Beating- (사이징과 고해에 따른 종이의 열화기구(제2보) -고해의 영향-)

  • 김봉용
    • Journal of Korea Technical Association of The Pulp and Paper Industry
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    • v.31 no.2
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    • pp.58-63
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    • 1999
  • Three kinds of papers were prepared from different beating degree of pulps. Physical and optical properties were examined to elucidate the deterioration mechanism of paper according to beating degrees. Changes of double folds, elongation, water retention value, DP, K/S value and visible, UV region light absorption spectra of those papers treated by UV light were studied. Double folds and brightness were decreased more rapidly by UV treatment with increasing of beating degree. The light absorption rates of pulps in visible and UV region were also increased with change of beating level. The formation of new hydrogen bonds and higher light absorption rate of pulps according to beating induced to absorb and interact with much UV light. These phenomena maybe brought about to accelerate paper deteriortion by UV treatment both optical and physical properties.

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Improvement of Sensitivity in Porous Silicon Alcohol Gas Sensors by UV Light (자외선조사에 의한 다공질 실리콘 알코올 센서의 감도 개선)

  • Kim, Seong-Jin;Choe, Bok-Gil
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.48 no.9
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    • pp.676-680
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    • 1999
  • To do breath alcohol measurement, a sensor is necessary that it can detect low alcohol gas concentration of 0.01% at least. In this work, a capacitance-type alcohol gas sensor using porous silicon layer is developed to measure low alcohol gas concentration. The sensor using porous silicon layer has some sensitivity at room temperature by very large effective surface area, but there is still much room for improvement. In this experiment, we measured the capacitance of the sensor under 254 nm UV light on the porous silicon layer, in which alcohol solution was kept in a flask at 25, 35, and $45^{\circ}C$ by a heater. As the result, the improvement of sensitivity by illuminating UV light was observed. The increasing rate of the capacitance was shown to be double more than those measured under UV-off state. It is supposed that UV light activates response of the oriental and interfacial polarizations which have slow relaxation time for AC field.

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A Study on Alignment of Nematic Liquid Crystal by Using Slanted Non-polarized Ultraviolet Light Irradiation on Polyimide Film (폴리이미드막표면위에 경사진 자외선 조사를 이용한 네마틱 액정의 배향에 관한 연구)

  • 서대식;황율연;이보호
    • Electrical & Electronic Materials
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    • v.10 no.5
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    • pp.461-466
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    • 1997
  • In this paper, we developed the new non-rubbing liquid crystal (LC) alignment techniques in the cell with slanted non-polarized ultraviolet (UV) light irradiation on polyimide (PI) film. It is shown that the uniform alignment for nematic (N) LC is obtained by using slanted non-polarized UV light irradiation on PI surface. We successfully obtained that the pretilt angle of NLC is generated about 3.3 degree in the cell with slanted non-polarized UV light irradiation with 70 degree on PI surface, for the first time. It is considered that the pretilt angle generation in NLC is attributed to interaction between the LC molecular and the PI, which is broken the polymer by slanted non-polarized UV irradiation. Therefore, we concluded that the uniform LC alignment is attributed to anisotropic dispersion force due to photo depolymerization with slanted non-polarized UV light irradiation on PI surface.

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Pretilt Angle Generation and EO Performance in MLC with Polarized UV Light Irradiation Polyimide surface (폴리이미드막 표면에 직선 편광된 UV광 조사에 의한 프리틸트각 발생과 전기광학특성)

  • 서대식;이정호;이창훈
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.10
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    • pp.878-884
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    • 1998
  • We have investigated that the monodomain alignment of nematic liquid crystal (NLC) is obtained with polarized ultraviolet(PUV) light irradiation on polyimide (PI) surface. The LC alignment capability increases with increasing the UV light irradiation time. The polarized UV light irradiation on oblique angle of 60。 irradiated on PI surface rotated by 90。 at 10 min. after being normally irradiated on PI surface at 30 min., the generated pretilt angle of NLC is about 2.5。. The pretilt angle of NLC is attributed to the interaction between the LC molecules and the asymmetric triangular structure of polymer surface due to photo-depolymerization of polymer with the oblique UV light on PI surface. The voltage -transmittance and response time characteristics of photo-aligned twisted nematic (TN)-LCD with UV light irradiation time 60 min. were almost same in comparison with the rubbing-treated TN-LCD.

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Studies on the improvement of UV sterilizer for toothbrush (가정용 칫솔 UV 살균기의 성능 개선법에 관한 연구)

  • Yang, Eun-Jung;Lee, Mi-Seon;Kim, Jung-Woo
    • The Journal of Natural Sciences
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    • v.11 no.1
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    • pp.41-44
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    • 1999
  • For the purpose of improving the UV sterilization for toothbrush, the sterilizing effects by the UV light were studied. When toothbrushes were treated with the UV light for 5, 15, 30, 60 minutes, the sufficient antibacterial effect were shown after 15 minutes with 80% of bactericidal effects. To prevent the brownish stain on the sterilizer which was caused by the long exposure of UV light, no UV treatment for two hours after 15 minutes exposure were scheduled and then 3 minutes re-exposure were performed, which showed 97% of bactericidal effect. Also, the antibacterial effects of the sterilizer showed different results depending on the position of the toothbrush, it was recommended to adjust toothbrush to be exposed by the UV light directly.

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A Study on the matter of Disinfection in UV/TiO2 Water Treatment process (UV/TiO2 수처리 공정에서의 살균에 관한 연구)

  • Lee, Gyu-Hwan;Lee, Sang-Jin;Lee, Yong-Jae;Rhee, Dong-Seok
    • Journal of Industrial Technology
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    • v.27 no.A
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    • pp.15-18
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    • 2007
  • This study investigated disinfection effect by general water purifier and water purifier with UV light disinfection. The results are as follows : (i) The general bacteria existed plentifully in a storage tank before treatment (ii) Water treated in water purifier did not meet the water treatment regulation standard since the presence of bacteria, whereas with UV light application the regulation standard is totally satisfied. (iii) Photocatalytic disinfection process with UV light in the presence of $TiO_2$ more effectively killed general bacteria than UV light only.

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Effects of UV light irradiation condition and imidization temperature for the generation of pretilt angle on polyimide surfaces (폴리이미드 표면에서의 프리틸트각 발생에 대한 UV조사 조건과 이미드화온도의 영향)

  • Yu, Mun-Sang;Seo, Dae-Shik;Hwang, Jeoung-Yeon
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1998.11a
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    • pp.61-64
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    • 1998
  • We have investigated the effects of ultraviolet (UV) light irradiation condition and imidization temperature for the generation of pretilt angle in nematic liquid crystal (NLC) on the two kinds of the polyimide (PI) surfaces. High pretilt angle of NLC is generated with oblique p-polarized UV light irradiation of 30$^{\circ}$ on PI surface for 20 min. Also, the high pretilt angle of NLC is generated with oblique p-polarized UV light irradiation of 10-30$^{\circ}$ on PI surface at 20min. The pretilt angle of NLC decreases with increasing the imidization temperature on all rubbed PI surfaces ; the pretilt angle of NLC with oblique p-polarized UV light irradiation of 30$^{\circ}$on PI surface decreases with increasing the imidization temperature. The high pretilt angle of NLC is observed due to high photo-depolymerization reaction by low surface energy at low imidization temperature. We suggest that the pretilt angle of NLC is strongly attributed to the photo-depolymerization reaction with the UV light irradiation condition and imidization temperature.

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WTP UV Disinfection System (국내하수처리장 자외선소독조 운영실태 및 기술동향)

  • Lee, J.Y.;Kim, Y.T.;Lee, T.J.
    • 유체기계공업학회:학술대회논문집
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    • 2005.12a
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    • pp.126-132
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    • 2005
  • UV disinfection system allows the disinfection of municipal and industrial water and wastewater without the use of expensive chlorination and dechlorination techniques, labor intensive equipments In traditional ultraviolet systems the UV lamps are seperated from water by quartz sleeves. quartz is one of. the few materials that is virtually transparent to UV light, the UV lamp is placed inside the Quartz sleeve. UV light from the lamp is passed through the quartz and into the water, thereby providing disinfection. In fluoropolymer tube-used non-contact UV systems, the water flows through fluoropolymer plastic tubes. banks of UV lamps surround these tubes such that each tube gets exposed to ultra violet light from all sides. in non-contact design the lamps operates at almost constant temperature. this design is extremly efficient in the utilization of UV energy and superior to conventional contact- systems.

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Development of a Sunscreen Formulation that Increases UV Blocking Ability by UV Light (자외선에 의해 자외선 차단 효율이 상승하는 선크림 제형 개발)

  • Choi, Minsung;Cho, Hyeongjin;Song, Kyunghee;Song, Seungjin;Kang, Nae-Gyu;Park, Sun-Gyoo
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.45 no.2
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    • pp.139-150
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    • 2019
  • This study is investigated sunscreen formulation that enhances UV absorption efficiency by UV light. Ethylhexyl methoxycinnamate (OMC) is one of the most common UV filters. Many studies have been conducted about photostability of OMC. It is well known that under the UV exposure, trans-OMC could turn to cis-OMC, or produce various photoproducts including its dimers. Those chemical structure changes were understood as the reason of a decrease in UV absorption efficiency upon UV exposure. However, it was found that OMC and isoamyl p-methoxycinnamate (IMC) could even enhance its UV absorption efficiency when it was exposed to UV light in an environment similar to actual use. In order to develop sunscreen formulation that enhances UV absorption efficiency by UV light, emollient with high polarity and compatibility should be avoided from the formular. Those emollient seemed to prevent OMC or IMC from producing photoproducts under UV light. Finally, a sunscreen formulation (UV sensing SPF boosting formular) enhancing UV absorption efficiency by UV was developed by the UV activated SPF boosting technology, and the effect of the sunscreen was evaluated. in vitro SPF of the sunscreen was increased from 50.69 to 72.33 when it was exposed to UV light and its in vivo SPF (53.7) was 56.10% higher than that of the control sunscreen (below 34.4).