• Title/Summary/Keyword: UV emission

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Study on Compound Humidifier Employing UV-LED using Environmental Life Cycle Assessment (환경전과정평가에 기반한 UV-LED 를 사용한 복합식 가습기에 관한 연구)

  • Choi, Won-Sik;Park, Si-Hyun;Lee, Si-Wang;Jung, Young-Mi;Yi, Hwa-Cho
    • Journal of the Korean Society for Precision Engineering
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    • v.29 no.9
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    • pp.931-937
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    • 2012
  • In this study, we assessed environmental impacts of compound humidifiers using environmental life cycle assessment and presented the ways to improvements in energy consumption of them. We found eco-design parameters and $CO_2$-eq emissions in each stage of raw material acquisition, manufacturing, transportation, use and disuse in life cycle of the compound humidifiers. The highest $CO_2$ emission is found to be in the stage of use among all stages of life cycle, which is mainly due to power consumption in thermal heating of heating coil for sterilization during humidification. The power consumption and $CO_2$ emission in the stage of use can be reduced to 1/4 and 1/3 at the highest estimate through improvement of sterilization method, respectively. We suggested the replacement of conventional thermal heating coil by ultra violet light-emitting diodes (UV-LED) for sterilization and then presented the experimental results on the sterilization effects of UV-LEDs.

Investigation of the luminescence properties of ZnO nanostructures (ZnO 나노 구조의 형상에 따른 발광 특성에 관한 연구)

  • Jung, Mi-Na;Ha, Seon-Yeo;Park, Seung-Hwan;Yang, Min;Kim, Hong-Seung;Lee, Uk-Hyeon;Yao, Takafumi;Chang, Ji-Ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • v.9 no.1
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    • pp.1013-1016
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    • 2005
  • ZnO nanostructure was fabricated by catalyst-free method using Zn powder in air. The growth temperature was controlled from 450$^{\circ}$C to 600$^{\circ}$C, and the structural and optical properties were investigated by scanning electron microscopy (SEM), photoluminescence (PL), energy dispersive X-ray spectroscopy (EDX) and cathodoluminescence (CL). From all samples both ZnO tetrapods and clusters were observed. No significant dispersion was observed from the ZnO tetrapods, however, ZnO clusters show considerable change in density and size. From the EDX results, atomic composition difference was found. The clusters have O-deficiencies, while tetrapods have stoichiometric composition. Strong luminescence was observed at room temperature. From room temperature PL, UV emission at 380 nm and green emission at 500 nm were observed, and the intensity ratio ($I_{uv}/I_{green}$) increased as growth temperature increases. CL measurements show that the UV emission is closely related with tetrapods and the green emission is dominated from the clusters.

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Fabrication of Red LED with Mn activated $CaAl_{12}O_{19}$ phosphors on InGaN UV bare chip (InGaN UV bare칩을 이용한 $CaAl_{12}O_{19}:Mn^{4+}$ 형광체의 적색 발광다이오드 제조)

  • Kang, Hyun-Goo;Park, Joung-Kyu;Kim, Chang-Hae;Choi, Seung-Chul
    • Journal of the Microelectronics and Packaging Society
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    • v.14 no.4
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    • pp.87-92
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    • 2007
  • A $CaAl_{12}O_{19}:Mn^{4+}$ red phosphor showed the highest emission intensity at a concentration of 0.02mole $Mn^{4+}$ and the high crystallinity and luminescent properties were obtained at $1600^{\circ}C$ firing temperature for 3hr. The synthesized phosphor showed a broad emission band at 658nm wavelength. Red light-emitting diodes(LEDs) were fabricated through the integration of on InGaN UV bare chip and a 1:3 ratio of $CaAl_{12}O_{19}:Mn^{4+}$ and epoxy resin in a single package. This coated LED can be applicable to make White LEDs under excitation energy of UV LED.

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Peculiar Features in the Emission Lines of Symbiotic Stars AG Draconis and UV Aurigae

  • Kim, Soo Hyun;Yoon, Tae Seog;Oh, Hyung-il
    • The Bulletin of The Korean Astronomical Society
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    • v.43 no.2
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    • pp.59.3-59.3
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    • 2018
  • 공생별 AG Dra와 UV Aur에 대해 지난 10여년간 보현산천문대 1.8m망원경과 고분산 에셀 분광기 BOES(BOao Echelle Spectrograph)로 분광관측을 수행해 왔다. 최근 2017년 11월 - 2018년 6월 관측에서, AG Dra의 Fe II 방출선과 UV Aur $H{\alpha}$ 방출선이 예년과 다른 변화 모습을 보이고 있음을 찾아내었다. 이에 대한 변화 원인을 공전주기, 밝기 변화 또는 다른 이유와 연관지어 설명하고자 한다.

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Synthesis and Characterization of Soluble Polyaniline and TiO2 Composite

  • Kim, Byoung-Ju;Kang, Kwang-Sun
    • Current Photovoltaic Research
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    • v.3 no.3
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    • pp.71-74
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    • 2015
  • Soluble polyaniline was synthesized by attaching titanium isoproxide ($Ti(OPr)_4$) to the amine group of the aniline. Approximately 1 to 1 molar ratio of aniline and $Ti(OPr)_4$ was mixed and polymerized with ammonium persulfate. The FTIR result showed clear difference between $TiO_2$-aniline composite ($TiO_2An$) and $TiO_2$-polyaniline composite ($TiO_2PAn$). Although the $TiO_2An$ had negligible UV-visible absorption, the $TiO_2PAn$ showed strong absorption in the UV-visible region. Photoluminescence (PL) peaks of $TiO_2An$ were shifted toward red with the reduction of the excitation energy, which could be due to the multiple emission centers. The luminescence peak shift stopped at 501 nm. The PL spectra of $TiO_2PAn$ exhibited three emission peaks at 2.88 eV (430 nm), 2.48 eV (501 nm) and 2.22 eV (558 nm). The new emission center (2.22 eV) was observed after polymerization. Field emission scanning electron microscope image showed crack-free composite film.

Synthesis, photoluminescence and thermal properties of laponite-X (X = Eu, Tb) phosphors (라포나이트-X(X = Eu, Tb) 형광체의 합성 및 열적 안정성과 발광특성 연구)

  • Kim, Pyo-Ra;Son, Dong-Min;Lee, Han-Na;Kim, You-Hyuk
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.19 no.4
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    • pp.196-201
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    • 2009
  • In order to give emission functionality for laponite the laponite-X (x = Eu, Tb) phosphors were prepared by calcination of cryogels which were prepared through Na ion exchange reaction with Eu and Tb ions. Thermal stability and emission properties of new laponite-X (X = Eu, Tb) phosphors were investigated by X-ray diffractormeter and UV/VUV spectrofluorometer. The phosphors were stable around up to $600^{\circ}C$ and new crystalline phases were observed at $700^{\circ}C$. Red and green emissions of phosphors under UV/VUV excitation were also identified at $300^{\circ}C$ and $500^{\circ}C$ as emission peaks of $Eu^{3+}$ and $Tb^{3+}$, respectively.

Luminescence Characteristics of Blue and Yellow Phosphor for Near-Ultraviolet (자외선 여기용 청색 및 황색 형광체의 발광특성)

  • Choi, Kyoung-Jae;Park, Joung-Kyu;Kim, Kyung-Nam;Kim, Chang-Hae;Kim, Ho-Kun
    • Journal of the Korean Ceramic Society
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    • v.43 no.5 s.288
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    • pp.304-308
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    • 2006
  • We have synthesized a $Eu^{2+}-activated\;Sr_3MgSi_2O_8$ blue phosphor and $(Sr,Ba)_2SiO_4$ yellow phosphor and prepared white LEDs by combining these phosphors with a InGaN UV LED chip. Three distinct emission bands from the InGaN-based LED and the two phosphors are clearly observed at 405 nm, 460 nm and at around 560 nm, respectively. The 405 nm emission band is due to a radiative recombination from a InGaN active layer. This blue emission was used as an optical transition of the $Sr_3MgSi_2O_8:Eu$ blue phosphor and $(Sr,Ba)_2SiO_4:Eu$ yellow phosphor. The 460 nm and 560 nm emission band is ascribed to a radiative recombination of $Eu^{2+}$ impurity ions in the $Sr_3MgSi_2O_8:Eu$ and $(Sr,Ba)_2SiO_4$ host matrix. As a consequence of a preparation of UV White LED lamp using the $Sr_3MgSi_2O_8:Eu$ blue phosphor and $(Sr,Ba)_2SiO_4:Eu$ yellow phosphor, the highest luminescence efficiency was obtained at the ration of epoxy/two phosphor (1/0.2361). At this time, the CIE chromaticity was CIE x = 0.3140, CIE y = 0.3201 and CCT (6500 K).

A Study on the Luminescent Characteristics of YPO4:Pr3+ Phosphor by the Content Ratio of Pr6O11 and Calcination Temperature (Pr6O11의 함량 및 열처리 조건에 따른 YPO4:Pr3+ 형광체의 발광 특성 연구)

  • Min Jun Kim;Seong Eui Lee
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.37 no.1
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    • pp.68-73
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    • 2024
  • In this study, the praseodymium-doped yttrium phosphate (YPO4:Pr3+) powder, which is well known for its high luminescent efficiency, and long life in the UV range, was synthesized with various content ratios of Pr6O11 and calcination temperature. Crystal structure and luminescent properties of various phosphor powders based on different concentrations and calcination conditions were characterized by XRD (X-Ray Diffraction) and PL (photoluminescence) spectrometers. From the XRD analysis, the structure of YPO4:Pr3+ which is calcinated at 1,200℃ was stable tetragonal phase and crystal size was calculated about 25 nm by Scherrer equation. PL emission of YPO4:Pr3+ with a different content ratio of Pr6O11 by excitation λexc=250 nm shows that 0.75 mol% phosphor powder has maximum PL intensity and PL decreases with the increase of the ratio of Pr6O11 up to 1.25 mol% which is caused by changes of crystallinity of phosphor powders. With increasing dopant ratio, photo-luminescence Emission decreases due to Concentration quenching, which is commonly observed in phosphors. Currently, 0.75 mol% is considered the optimal doping concentration. A hybrid ultraviolet-emitting device incorporating YPO4:Pr3+ fluorescent material with plasma discharge was fabricated to enhance UV germicidal effects while minimizing ozone generation. UV emission from the plasma discharge device was shown at about 200 nm and 350 nm which caused additional emission of the regions of 250 nm, 315 nm, and 370 nm from the YPO4:Pr3+ phosphor.

Sterilization of Escherichia coli Based on Nd: YAG Resonator with a Pulsed Xenon Flashlamp

  • Kim, Hee-Je;Kim, Dong-Jo;Hong, Ji-Tae;Xu, Guo-Cheng;Lee, Dong-Gil
    • Journal of Electrical Engineering and Technology
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    • v.6 no.2
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    • pp.275-279
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    • 2011
  • Sterilization of Escherichia coli (E. coli) is examined using a unique pulsed ultra-violet (UV) elliptical reactor based on Nd:YAG laser resonator, UV radiation from a pulsed xenon flashlamp. The light from the discharge has a broadband emission spectrum extending from the UV to the infrared region with a rich UV contained. Sterilization method by using the UV light is fast, environment-friendly and it does not cause secondary pollution. A Nd:YAG laser resonator having elliptical shape has advantage of concentrating the radiation of the UV light at two foci as the quart sleeve filled with E. coli. The primary objective of this research is to determine the important parameters such as pulse per second (pps), the applied voltage for sterilizing E. coli by using an UV elliptical reactor. From the experiment result, the sterilization effect of UV elliptical reactor is better than that of UV cylindrical reactor, and it can be 99.9% of sterilization at 800V regardless of the pps within 10 minutes.