• 제목, 요약, 키워드: UV wavelength

검색결과 634건 처리시간 0.039초

Photoluminescence of SrO-$Al_2O_3$ Doped with Eu and Ce Excited at near UV

  • Han, Sang-Hyuk;Kim, Young-Jin;Chung, Sung-Mook
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.654-656
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    • 2004
  • The effect of excitation energy and various dopants(Eu and Ce) on the emission wavelength and intensity were investigated. According to PL spectra, SrO-$Al_2O_3$ phosphors had wide absorption band at nUV. By substituting Ce for Eu, the emission band and excitation wavelength were shifted to shorter wavelength. Ce doped $SrAl_2O_4$ and $Sr_4Al_{14}O_{25}$ showed greenish blue(475nm) and blue(400nm), respectively.

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초음파 발생 미스트를 이용한 TiO2 광촉매 시스템에서의 가스상 톨루엔 제거 (Removal of Gaseous Toluene Using a TiO2 Photocatalytic System with Mist Generated by Ultrasonic Atomization)

  • 최민석;한세현;장성찬;정용원
    • 한국대기환경학회지
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    • v.25 no.3
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    • pp.211-218
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    • 2009
  • Feasibility study of using $Ti0_2$ mist generated by ultrasonic atomization for photocatalytic degradation of gaseous toluene was attempted in this study. For this, the photocatalytic reactor consisting of mist generator and photo-reactor was designed. Most of experimental results showed that steady state reached about 30 minutes after the start of experiments. The effects of $Ti0_2$ concentration, toluene concentration, and UV wavelength on toluene removal ratio were investigated. It was found that the highest removal efficiency was obtained when $Ti0_2$ concentration was 0.6 g/L in slurry. At this condition, it was found that the toluene removal efficiency increased as toluene concentration in feed decreased. In order to investigate the effect of UV wavelength, experiments were carried out using three UV lamps with different UV wavelength. The results showed that the highest removal efficiency was achieved when the lamp with the shortest wavelength were employed.

PRELIMINARY STUDIES ON NATURAL PLANT EXTRACTS AS SUNSCREEN AGENTS

  • Lee, K.T.;Kim, J.H.
    • 대한화장품학회지
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    • v.24 no.3
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    • pp.81-88
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    • 1998
  • The aim of this study is to evaluate several plant extracts with a view to developing UV sunscreen agents. In this study, 150 plant extracts were screened to elucidate their UV spectra using spectrophotometric method. Several plant extracts such as Phellodendron amurense, Morus alba, Rhododendron mucronulatum, Brassica alba have strong absorbency at UVA region (350nm), the suntanning wavelength. And Sophora flavescens, Caesalpinia sapper, Morus alba, Phellodendron amurense, showed absorption plateau value at UVB region (308nm), the erythema action wavelength. These extracts have a good absorbency property as synthetic filter and could be served as substitutes for synthetic UV sunscreen agents.

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렌즈에서 UV 차단효과의 평가방법 및 적용 (The Estimation Method and Application of UV-cut effect in Lens)

  • 김용근
    • 한국안광학회지
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    • v.6 no.1
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    • pp.107-110
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    • 2001
  • 렌즈에서 UV-A선의 차단효율을 평가하기 위해 320~400nm 영역에서 광 투과율을 측정하였다. 기준 CR-39와 sample을 320~400nm 영역에서 광 투과율을 적분하여 면적을 구하였으며, 이들의 면적 대비로 UV-A 차단효율 factor ${\alpha}$, ${\beta}$를 설정하였다. CR-39 렌즈의 질대 차단효율 ${\alpha}$ CR=0.59 값을 얻었다. UV-A 차단효과를 평가할 렌즈의 절대차단효율 ${\alpha}$ 값이면 상대차단효율 ${\beta}$ 값은 $1.69{\alpha}$ 값을 얻었다. 절대적 및 상대적 UV 제거 지수는 각각 $a=(1-{\alpha}){\times}100%$, $b=(1-{\beta}){\times}100%$을 이용하여 얻었다.

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TiO2 광촉매를 이용한 LAS의 제거에 관한 연구 (A Study on the Removal of LAS using TiO2 Photocatalyst)

  • 김효정;오윤근;류성필
    • Journal of Environmental Science International
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    • v.11 no.7
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    • pp.757-763
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    • 2002
  • The objective of this study is to delineate removal efficiency of the Linear alkylbenzene sulfonates(LAS) in solution by $TiO_2$ photocatalytic oxidation as a function of the following different experimental conditions : initial concentration of LAS, $TiO_2$ concentration, UV wavelength and pH of the solution. It was increased with decreasing initial concentration of LAS and with decreasing pH of the solution. Removal efficiency increased with increasing $TiO_2$ concentration but was almost the same at $TiO_2$ concentration of 2 g/L and 3 g/L, i.e., for initial LAS concentration of 50 mg/L. It was removal efficiency was 85% at 150 min in the case of $TiO_2$ concentration of 0.5 g/L but 100% after 150 min in the case of $TiO_2$ concentration of 1 g/L, 100% after 110 min in the case of $TiO_2$ concentration of 2 g/L and 3 g/L. UV wavelength affection on the removal efficiency of LAS decreased in the order of 254, 312 and 365 nm as increasing wavelength. But the removal efficiency of LAS was nearly the same at UV wavelength of 254 nm and 312 nm.

Effect of UV Radiation on Early Growth of Korean Rice Cultivars(Oryza sativa L.)

  • Choi, Kwan-Sam;In, Jun-Gyo;Kang, Si-Yong;Bae, Chang-Hyu;Lee, Hyo-Yeon
    • 한국작물학회지
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    • v.44 no.3
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    • pp.296-301
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    • 1999
  • The concerns on the crop damage by ultraviolet (UV) radiations is increasing owing to the decrease of their absorbing stratospheric ozone in the tropospheric. Cultivar differences on early growth of UV radiation among five Korean rice cultivars, four japonica types and one Tongil type (indica-japonica cross hybrid), were studied. Pot-seeded rice plants were grown under four different radiation conditions, i.e., visible radiation only, visible radiation with supplemented with high or low dose of UV-B (280~320 nm in wavelength) and UV-C (less than 280 nm in wavelength). The inhibitory degree on plant height, shoot and root weight and length of leaf blade and leaf sheath were determined at 40 days after seeding. UV-C showed the most severe inhibitory effect on the degree of biomass gain and leaf growth in most cultivars examined, followed by high UV-B and low UV-B. Among the cultivars used, the Kuemobyeo was the most sensitive cultivar and had not repair or showed resistance ability to continued irradiation of UV radiation. However, Janganbyeo and Jaekeon showed different responses that the elongation of leaf blades was promoted on 2nd and 3rd leaves and inhibited on 4th and 5th leaves but this inhibitory degree was reduced on 6 th and 7th leaves. Such tendency on leaf growth means that both cultivars had low sensitivity and most resistant ability to continued irradiation of UV radiation. While Tongil showed different response to enhanced UV radiation, ie., low UV-B promoted leaf growth but the inhibitory was severely increased by continued irradiation of high UV-B and UV-C, which means that Tongil had high threshold of UV radiation for response as an inhibitory light of plant growth. The results of this study indicate that the differences on sensitivity or resistant to the effects of UV radiation were existed among Korean rice cultivars.

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광반응을 이용한 Triclosan 분해에서의 UV 광세기와 파장의 효과 (The Effect of UV Intensity and Wavelength on the Photolysis of Triclosan (TCS))

  • 손현석;최석봉;;조경덕
    • 대한환경공학회지
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    • v.27 no.9
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    • pp.1006-1015
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    • 2005
  • 본 연구에서는 항균제로 광범위하게 사용되는 triclosan (TCS)의 광분해시, 광분해 효율을 결정하는 OH 라디칼의 기여도를 조사하였다. TCS의 광분해 반응은 365 nm에서 모든 광세기 조건과 254 nm에서 낮은 광세기 조건들에서, 반응 초기 약 5분에서의 분해양상은 유사일차 속도반응 모델을 따르고 있었다. 또한 TCS의 광분해시 메탄올을 $H_2O$ 대신에 용매로 사용하였을 경우 OH 라디칼의 저해작용에 의하여 TCS 분해속도가 감소되었다. TCS의 광분해 속도는 파장이 감소하고, 광세기가 증가함에 따라 유의한 증가를 보였다. TCS의 광분해시 254 nm에서는 $5.77{\times}10^{-5}$ einstein $L^{-1}min^{-1}$이상의 광세기와, 365 nm에서는 $1.56{\times}10^{-4}$ einstein $L^{-1}min^{-1}$ 보다 낮은 광세기 조건에서 photon의 기여도가 증가함을 보였다. 또한 photon의 기여도가 큰 광세기 조건들에서의 TCS에 의해 이용된 quantum yield는 254 nm보다 365 nm에서 높은 효율을 보였다. TCS의 중간부산물로서는 dibenzodichloro-p-dioxin (DCDD)와 dibenzo-p-dioxin가 365 nm하의 $1.37{\times}10^{-4}$$1.56{\times}10^{-4}$ einstein $L^{-1}min^{-1}$의 광세기 조건에서 모두 검출되었다. Dichloro-phenol과 phenol 역시 광반응의 부산물로서 모든 실험에서 발견되었다. 실험 결과를 토대로 TCS의 광분해 메커니즘을 제안하였다.

자외선 조사에 의해 표면 개질된 PVA 편광필름의 광학특성 (Optical Properties of PVA Polarizing Films Surface-modified by UV Irradiation)

  • 구광회;장진호
    • 한국염색가공학회지
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    • v.18 no.6
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    • pp.49-56
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    • 2006
  • Surface treatment using UV irradiation was carried out to improve optical properties of polarizing films. The effects of UV energy of the UV-treated PVA films were investigated by measuring reflectance, surface roughness, contact angles, ESCA, and ATR. Reflectance decreased at wavelength of 450 nm or less and surface roughness increased with increasing UV energy. Water contact angle increased in the irradiated PVA films and surface energy decreased with increase in w energy. An analysis showed that the OH groups were broken and some new groups were introduced such as C=C and C=O bonds together with increased $O_{1s}/C_{1s}$, resulting in the observed surface modification effect. Surface modified PVA polarizing films showed improvement in light transmittance of polarizing films at high wavelength region without deteriorating polarization efficiency, which was not affected by UV irradiation sequence during manufacturing processes such as coloring and drawing.

UV-Vis 분광분석에 의한 전기변압기 내 절연지 열화도 측정 (Application of UV-Vis Spectroscopic Analysis for Transformer Insulating Paper Degradation)

  • 공호성;한흥구
    • Tribology and Lubricants
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    • v.35 no.3
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    • pp.151-157
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    • 2019
  • Insulated oil degradation produces charged by-products, such as acids and hydro-peroxides, which tend to reduce the insulating properties of the oil. In this study, UV-vis spectroscopy measurement technology is developed and experimentally compared with other measurement methods, such as the titration method and IR spectroscopy, to validate its ability to monitor the degradation of electrical insulating paper. The degradation characteristics of the insulating paper are appropriately represented through various types of measurement methods, such as the Tan (delta) method, $CO_2$ gas production measurement, the titration method, and IR spectroscopy. The results are demonstrated to be well comparable to a change in the fluorescence emission ratio (FER), which is defined as the shift in fluorescence intensity in the measured wavelength range, and also to the chromatic ratio, which is defined as a color shift to longer wavelength ranges. The results also show that, by using UV-vis spectroscopy, it is possible to detect the degradation of the insulating paper. This study suggests that UV-vis spectroscopy can be applied as an alternative to high-performance liquid chromatography, which is the internationally recognized measurement technology for cellulose paper degradation. The FER detector is also verified to be useful as an effective condition-monitoring device for power transformers.