• Title, Summary, Keyword: UV (ultraviolet) light

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Design and Analysis of Flame Signal Detection with the Combination of UV/IR Sensors (UV/IR센서 결합에 의한 불꽃 영상검출의 설계 및 분석)

  • Kang, Daeseok;Kim, Eunchong;Moon, Piljae;Sin, Wonho;Kang, Min-goo
    • Journal of Internet Computing and Services
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    • v.14 no.2
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    • pp.45-51
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    • 2013
  • In this paper, the combination of ultraviolet and infrared sensors based design for flame signal detection algorithms was proposed with the application of light-wavelength from burning. And, the performance result of image detection was compared by an ultraviolet sensor, an infrared sensor, and the proposed dual-mode sensors(combination of ultraviolet and infrared sensors).

UV Blocking Coatings by Combination of Organic-inorganic Hybrid Materials and UV absorbers (유-무기 하이브리드 재료와 자외선 흡수제의 배합에 의한 자외선 차단 코팅)

  • Yu, Dong-Sik;Lee, Ji-Ho;Ha, Jin-Wook
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.7 no.6
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    • pp.1296-1301
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    • 2006
  • The human eye is exposed to UV and visible light. UV light exposure becomes harmful to the eye. Protection for eyes should block all ultraviolet rays. In our study, organic-inorganic hybrid materials have been applied to UV blocking coatings with UV absorbing materials on transparent plastics. The optical properties of UV blocking coatings were investigated in PMMA, CR 39 and PC substrates. In case of all UV absorbers, the transmission of UV light decreases with an increased amount of absorber. Our findings indicate that PMMA significantly reduced the transmission of UV radiation, CR 39 showed moderate decrease, while UV-uncoated PC had some UV blocking properties. Adhesion, hot water resistance and chemical resistance of the UV-coated CR 39 lenses were good. Pencil hardness were 4H. Abrasion resistance were poor.

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Protection Method for Diameter-downsized Fiber Bragg Gratings for Highly Sensitive Ultraviolet Light Sensors

  • Seo, Gyeong-Seo;Ahn, Tae-Jung
    • Current Optics and Photonics
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    • v.2 no.3
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    • pp.221-225
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    • 2018
  • We suggested the use of miniature hollow glass tubes having high ultraviolet (UV) transmission characteristics for the protection of optical-fiber-type UV sensors. We have recently proposed a highly sensitive optical sensor in the UV spectral range, using a fiber Bragg grating (FBG) coated with an azobenzene polymer as the photoresponsive material. In this study, we used UV-transparent miniature glass tubes to protect the etched FBG with the azobenzene polymer coating. This technique will be very useful for protecting various fiber-based UV sensors.

Fabrication of a Planar UV Lighting Device Utilizing Cs3Sb Photocathode Emitters

  • Jeong, Hyo-Soo
    • Journal of the Korean Physical Society
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    • v.71 no.12
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    • pp.993-996
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    • 2017
  • Planar ultraviolet (UV) light sources with uniform intensity are ideal for UV treatments. A newly conceived planar UV lighting device utilizing $Cs_3Sb$ mono-alkali antimonide photocathodes as flat electron emitters is presented and analyzed here. The design concept involves a panel device that utilizes photocathodes operated in a reflection mode with an external excitation light source. The excitation light source is in the blue visible light range. Commercially available UV phosphors are used as a light source of desirable UV wavelengths. The light emission characteristics of the device are investigated by measuring the optical parameters as function of applied anode voltage. The UV light emission shows that cold UV light with the spectral characteristics of near-monochromatic distribution are most effective. It also demonstrates that the UV intensity is sufficient for the UV treatment. More importantly, the planar UV lighting device is mercury free. These make them suitable for all UV applications.

A Study on the Properties Changes of Wool Fabrics Dyed with Safflower under Ultraviolet(UV)-Light (홍화 염색 모직물의 자외선에 의한 성능 변화 연구)

  • Shin, Youn-Sook;Choi, Seung-Youn
    • Fashion & Textile Research Journal
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    • v.10 no.2
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    • pp.249-253
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    • 2008
  • The purpose of this study was to investigate the properties changes of wool fabrics dyed with safflower red and yellow colorants under Ultraviolet(UV)-light. For this purpose, the wool fabrics dyed with safflower red and yellow colorants were compared with each other after uv-light exposure in terms of K/S value, color changes(${\Delta}E$), morphology, and strength retention. K/S value rapidly decreased with increasing exposure time, but K/S value of the samples dyed with safflower yellow colorants decreased less than that of the samples dyed with safflower red colorants. In color changes, as increasing exposure time, $L^*$ and $b^*$ increased, $a^*$ decreased, and thereby ${\Delta}E$ increased in the samples dyed with safflower red colorants, $L^*$ increased, $a^*$ and $b^*$ decreased, and so ${\Delta}E$ increased in the samples dyed with safflower yellow colorants, indicating fading away by uv-light and changes of hue, value and chroma value. But the color change of samples dyed with safflower yellow colorants was less than that of samples dyed with safflower red colorants. SEM pictures showed a severe degradation by uv exposure, regardless of colorants type. Tensile strength slowly decreased until 14 days, and rapidly decreased until 21 days and slowly decreased. Strength retention of the samples dyed with safflower yellow colorants was higher than that of the samples dyed with safflower red colorants.

Ultraviolet Wave Length Effective in the Sporulation of Didymella bryoniae, a Gummy Stem Blight Fungus in Cucurbits, and the Disease Control Effect by the Use of Ultraviolet Light-Absorbing Vinyl Film (박과작물 덩굴마름병권 Didymella bryoniae의 포자형성 유효 자외파장과 자외선 흡수필름을 이용한 병 방제효과)

  • 권미경;홍정래;기운계;조백호;김기청
    • Plant Disease and Agriculture
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    • v.5 no.1
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    • pp.20-26
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    • 1999
  • Ultraviolet light is required for the sporulation of Didymella bryoniae, a gummy stem blight fungus in cucurbits such as watermelon, melon, oriental melon, cucumber and pumpkin. In this experiment, the upper limit of wave length for the production of pycnidia of D. bryoniae was 365 nm - 375 nm. Two plastic houses were covered with either common transparent film (wave length longer than 225 nm is transmitted) or UV-absorbing film ( wave lenght shorter than 388 nm is absorbed). In both houses, seedlings inoculated with D. bryoniae were placed in the center of the house at 30 days after transplantation of watermelon (cv. Whanhoseong), and the disease incidences between the houses were compared until 80 days after transplantation. The number of disease lesions and incidence of pycnidia-producing lesions under the UV-absorbing film were reduced by 90% and 80%, respectively, compared to the common transparent film. The internode lengths of plants grown in the two houses were not significantly different, but the plants grown under the UV-absorbing film had longer vines and more leaves than plants under the common transparent film. However, fruit characters such as weight, length, width, rind thick and brix, were not different between the two houses. Occurrence of aphids was reduced in the UV-absorbing film, but those of mites or diseases (powdery mildew and sooty mold) were not different between the houses. These results suggest that disease incidence of gummy stem blight of watermelon in the greenhouse can be controlled by the use of UV-absorbing film.

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Analysis of Deep-Trap States in GaN/InGaN Ultraviolet Light-Emitting Diodes after Electrical Stress

  • Jeong, Seonghoon;Kim, Hyunsoo;Lee, Sung-Nam
    • Journal of the Korean Physical Society
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    • v.73 no.12
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    • pp.1879-1883
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    • 2018
  • We analyzed the deep-trap states of GaN/InGaN ultraviolet light-emitting diodes (UV LEDs) before and after electrical stress. After electrical stress, the light output power dropped by 5.5%, and the forward leakage current was increased. The optical degradation mechanism could be explained based on the space-charge-limited conduction (SCLC) theory. Specifically, for the reference UV LED (before stress), two sets of deep-level states which were located 0.26 and 0.52 eV below the conduction band edge were present, one with a density of $2.41{\times}10^{16}$ and the other with a density of $3.91{\times}10^{16}cm^{-3}$. However, after maximum electrical stress, three sets of deep-level states, with respective densities of $1.82{\times}10^{16}$, $2.32{\times}10^{16}cm^{-3}$, $5.31{\times}10^{16}cm^{-3}$ were found to locate at 0.21, 0.24, and 0.50 eV below the conduction band. This finding shows that the SCLC theory is useful for understanding the degradation mechanism associated with defect generation in UV LEDs.

Generation of High Pretilt Angle in Liquid Crystal Cell with Slanted Non-Polarized Ultraviolet Light Irradiation on Polyimide Film as for Non-Rubbing Techniques (경사진 자외선을 폴리이미드막 표면에 조사한 넌러방법에 의한 액정소자의 고 프리틸트각의 발생)

  • Seo, Dae-Shik;Hwang, Lyul-Yeon;Lee, Bo-Ho
    • Proceedings of the KIEE Conference
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    • pp.1585-1587
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    • 1997
  • We investigated the generation of high pretilt angle for nematic liquid crystal (NLC) in the cell with slanted non-polarized ultraviolet (UV) light irradiation on two kinds of the polyimide (PI) film. It was shown that the monodomain alignment in NLC is obtained in the cell with slanted non-polarized UV light irradiation on PI surface. The pretilt angle of NLC is generated about 3 degrees in the cell with slanted non-polarized UV light irradiation with 70 degrees on PI surface without side chain. But, the pretilt angle of NLC is generated about 1 degree in the cell with slanted non-polarized UV light irradiation with 80 degrees on PI surface with side chain. We consider that the pretilt angle generation in NLC is attributted to anisotropic dispersion force between the LC molecular and the PI surface.

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UV/blue Light-induced Fluorescence for Assessing Apple Quality (자외선 유도 형광의 사과 성숙도 평가 적용)

  • Noh, Hyun-Kwon;Lu, Renfu
    • Journal of Biosystems Engineering
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    • v.35 no.2
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    • pp.124-131
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    • 2010
  • Chlorophyll fluorescence has been researched for assessing fruit post-harvest quality and condition. The objective of this preliminary research was to investigate the potential of fluorescence spectroscopy for measuring apple fruit quality. Ultraviolet (UV) and blue light was used as an excitation source for inducing fluorescence in apples. Fluorescence spectra were measured from 'Golden Delicious' (GD) and 'Red Delicious' (RD) apples using a visible/near-infrared spectrometer after one, three, and five minutes of continuous UV/blue light illumination. Standard destructive tests were performed to measure fruit firmness, skin and flesh color, soluble solids and acid content from the apples. Calibration models for each of the three illumination time periods were developed to predict fruit quality indexes. The results showed that fluorescence emission decreased steadily during the first three minutes of UV/blue light illumination and was stable within five minutes. The differences were minimal in the model prediction results based on fluorescence data at one, three or five minutes of illumination. Overall, better predictions were obtained for apple skin chroma and hue and flesh hue with values for the correlation coefficient of validation between 0.80 and 0.90 for both GD and RD. Relatively poor predictions were obtained for fruit firmness, soluble solids content, titrational acid, and flesh chroma. This research has demonstrated that fluorescence spectroscopy is potentially useful for assessing selected quality attributes of apple fruit and further research is needed to improve fluorescence measurements so that better predictions of fruit quality can be achieved.

380-nm Ultraviolet Light-Emitting Diodes with InGaN/AlGaN MQW Structure

  • Bae, Sung-Bum;Kim, Sung-Bok;Kim, Dong-Churl;Nam, Eun Soo;Lim, Sung-Mook;Son, Jeong-Hwan;Jo, Yi-Sang
    • ETRI Journal
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    • v.35 no.4
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    • pp.566-570
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    • 2013
  • In this paper, we demonstrate the capabilities of 380-nm ultraviolet (UV) light-emitting diodes (LEDs) using metal organic chemical vapor deposition. The epi-structure of these LEDs consists of InGaN/AlGaN multiple quantum wells on a patterned sapphire substrate, and the devices are fabricated using a conventional LED process. The LEDs are packaged with a type of surface mount device with Al-metal. A UV LED can emit light at 383.3 nm, and its maximum output power is 118.4 mW at 350 mA.