• Title/Summary/Keyword: Visible Light

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Feasibility Study of IAQ Enhancement by Visible Light Photocatalyst (가시광 응답형 광촉매 제조와 이를 활용한 실내공기환경 개선 적용 타당성 조사)

  • Lee, Tai-Kyu;Yoon, Woo-Sug;Kim, Dong-Hyung;Hwang, Chul-Soon;Lim, Ji-Hun;Yoon, Jung-Ho;Kim, Young-mi
    • KIEAE Journal
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    • v.4 no.2
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    • pp.37-40
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    • 2004
  • New visible photocatalyst(Nanovis$^{(R)}$) has been synthesized to overcome the barrier of limitation of UV light utilization of current $TiO_2$ photocatalyst. It was found that red shift of absorption spectrum to 550nm was achieved. Its physical properties were characterized by XRD, BET and TEM. It is also observed that Nanovis$^{(R)}$ has a photocatalytic activity for photodegradation of Trichloroethylene under visible light irradiation. V,VII group doped into substitutional sites of $TiO_2$ has proven to be indispensable for band-gap narrowing and photocatalytic activity. These test results lead us to conclude that Nanovis$^{(R)}$ can be used for IAQ improvemen and for photocatalytic water splitting to hydrogen.

A Study on the Volatile Organic Compounds Analysis Method for Visible Light-Responsive Photocatalyst Treated Vehicle Interior Materials (가시광촉매가 처리된 자동차 내장재의 VOC 분석방법에 대한 연구)

  • Choi, Sei Young
    • Elastomers and Composites
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    • v.48 no.3
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    • pp.221-224
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    • 2013
  • In this study, VOC analysis method of vehicle interior materials and parts treated to visible-light responsive photocatalyst was tested by sample bag filled with air instead of nitrogen. As a result, when analyzed VOC of vehicle interior materials and parts, sample bag filled with the nitrogen was not confirmed of effect reducing VOCs and formaldehyde. However, VOCs and formaldehyde of sample bag that was filled with air instead of nitrogen, decreased significantly. Reaction effect for visible light-responsive photocatalyst was confirmed that sample bag of vehicle interior materials and parts should be filled with air instead of nitrogen.

A COMPARATIVE STUDY OF THE EFFECTIVENESS IN POLYMERIZATION OF COMPOSITE RESIN CURED WITH VISIBLE LIGHT AND ARGON LASER SOURCE (가시광선과 아르곤 레이저에 의한 복합레진 중합 효과의 비교 연구)

  • Jun, Sang-Eun;Kim, Yong-Kee
    • Journal of the korean academy of Pediatric Dentistry
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    • v.23 no.2
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    • pp.327-346
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    • 1996
  • The purpose of this study was to evaluate the shear bond strengths, microhardness, compressive strength and contraction gap at the resin-tooth interface of two types of composite resins polymerized with visible light and argon laser sourse. The results from the present study can be summarized as follows ; 1. Resin samples polymerized either by argon laser or visible light did not show significant difference in their physical properties tested(p>.05). 2. The contraction gap at the resin tooth interface was found to be present in all samples but any significant difference between groups could not be established due to their variability. Although the superiority of argon laser over visible light in enhancing the physical properties of resin could not be elucidated in the present study, continous efforts are deemed to be worthwhile to investigate this area using different conditions and materials of experiment.

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Fabrication of Hybrid NiO/ACF/TiO2 Composites and Their Photocatalytic Activity Under Visible Light

  • Meng, Ze-Da;Han, Sang-Bum;Kim, Doo-Hwan;Park, Chong-Yeon;Oh, Won-Chun
    • Journal of the Korean Ceramic Society
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    • v.48 no.3
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    • pp.211-216
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    • 2011
  • Nickel oxide-doped ACF and $TiO_2$ composites (NiO/ACF/$TiO_2$) were prepared by a sol-gel method. The composite obtained was characterized by BET surface area measurements, X-ray diffraction, transmission electron microscopy and energy dispersive X-ray analysis. A methylene blue (MB) solution under visible light irradiation was used to determine their photocatalytic activity. Excellent photocatalytic degradation of the MB solution was observed using the $TiO_2$, Ti-ACF and NiO/ACF/$TiO_2$ composite under visible light.

Enhanced Visible Light Activity and Stability of TiO2 Nanopowder by co-doped with Mo and N

  • Hu, Shaozheng;Li, Fayun;Fan, Zhiping
    • Bulletin of the Korean Chemical Society
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    • v.33 no.4
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    • pp.1269-1274
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    • 2012
  • A visible light responsive N, Mo co-doped $TiO_2$ were prepared by sol-gel method. X-ray diffraction, TEM, $N_2$ adsorption, UV-vis spectroscopy, photoluminescence, and X-ray photoelectron spectroscopy were used to characterize the prepared $TiO_2$ samples. Doping restrained the phase transformation from anatase to rutile and reduced the particle sizes. The band gap was much narrowed after N, Mo co-doping. The photocatalytic activities were tested in the degradation of an aqueous solution of a reactive dyestuff, methylene blue, under visible light. The photocatalytic activities of doped $TiO_2$ were much higher than that of neat $TiO_2$. The photocatalytic stability of N, Mo co-doped $TiO_2$ was much better than that of N doped $TiO_2$.

Heterojunction of FeOOH and TiO2 for the Formation of Visible Light Photocatalyst

  • Rawal, Sher Bahadur;Chakraborty, Ashok Kumar;Lee, Wan-In
    • Bulletin of the Korean Chemical Society
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    • v.30 no.11
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    • pp.2613-2616
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    • 2009
  • FeOOH/$TiO_2$, a heterojunction structure between FeOOH and $TiO_2$, was prepared by covering the surface of the $\sim$100-nm-sized FeOOH particles with Degussa P25 by applying maleic acid as an organic linker. Under visible light irradiation (${\lambda}{\geq}$ 420 nm), FeOOH/$TiO_2$ showed a notable photocatalytic activity in removal of gaseous 2-propanol and evolution of $CO_2$. It was found that FeOOH reveals a profound absorption in the spectral range of 400 - 550 nm, and its valence band (VB) level is located relatively lower than that of $TiO_2$. The considerable photocatalytic efficiency of the FeOOH/$TiO_2$ under visible light irradiation was therefore deduced to be caused by the hole transfer between the VB of FeOOH and $TiO_2$.

Design and implementation of optical identification system using visible light and infrared

  • Lee, Seong-Ho
    • Journal of Sensor Science and Technology
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    • v.30 no.4
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    • pp.196-203
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    • 2021
  • In this study, an optical identification system was developed, wherein visible light is used to transmit the interrogating signal, and infrared is used to send the response signal. In the reader, visible light from a light emitting diode (LED) array was modulated via modified pulse width modulation for flicker-free illumination and dimming control. Moreover, the duty factor of the dimming control time was employed to control the illumination from the LED. In the transponder, the spike signal in the output of the high-pass filter was utilized to recover the interrogating signal while preventing interference from the 120-Hz noise from adjacent lighting lamps. The illumination was controlled in 26-86% range of the constant wave LED illumination by changing the duty factor from 20% to 90%. This configuration is advantageous for the construction of optical identification systems for automatic security check and car fare calculation at toll gates or parking facilities.

Design and Performance Analysis of Visible -Light Wireless Communication System using LED

  • Choi, Jae Myoeng
    • Journal of Advanced Information Technology and Convergence
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    • v.8 no.2
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    • pp.147-157
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    • 2018
  • In this study, we analyzed an outdoor visible light communication system and implemented it through a simulation. We designed a Reed-Solomon encoder, a variable interleaver structure, and set it to the Institute of Electrical and Electronics Engineers (IEEE) 802.15.7 PHY I specification mode. We also analyzed the performance of an additive white gaussian noise (AWGN) channel environment using a root-raised-cosine (RRC) filter, implemented a MATLAB simulation and analyzed its performance. The results showed a requirement for an additional signal-to-noise ratio (SNR) of approximately 1.5 dB in a 3-ray multipath visible light channel environment than in an AWGN environment.

MAC Protocol Design for Visual Light LAN using LED Light (LED 조명 기반의 무선 가시광 LAN 통신을 위한 MAC 프로토콜 설계)

  • Jeon, Jong-Bae;Choi, Jung-Ho;Kim, Sung-Man
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.4B
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    • pp.391-398
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    • 2011
  • In this paper, we propose a MAC protocol for visible light wireless LAN using LED light. The proposed MAC protocol has a function of automatic direction optimization for LED transceiver. There is periodical time slot for broadcasting and registration in the proposed MAC protocol. We used polling method for data transfer in the protocol since visible light is hard to detect carrier and collision by other mobile stations; thus we cannot use CSMA/CD method in visible light LAN. We also amended the MAC frame of IEEE 802.11 to propose a revised version for visible light wireless LAN using LED light. We investigate the performance of the proposed MAC protocol. When the bit rate of physical layer is 100 Mb/s, the net data throughput using the proposed MAC protocol is estimated to 94.386 Mb/s.

2D Slab Silicon Photonic Crystal for Enhancement of Light Emission in Visible Wavelengths

  • Cui, Yonghao;Lee, Jeong-Bong
    • 한국정보디스플레이학회:학술대회논문집
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    • 2008.10a
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    • pp.887-890
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    • 2008
  • We present 2D slab silicon-based photonic crystal optical insulator to enhance light emission efficiency of light-emitting diode (LED). A 2D slab silicon photonic crystal is designed in such a way that light emitting diode die can be placed in the middle of the silicon photonic crystal. The device creates light propagation forbidden region in horizontal plane for Transverse Electric (TE) light with the wavelength range of 450 nm to 600 nm.

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