• Title/Summary/Keyword: visible-LED

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Visible Light Communication Method for Personalized and Localized Building Energy Management

  • Jeong, Jin-Doo;Lim, Sang-Kyu;Han, Jinsoo;Park, Wan-Ki;Lee, Il-Woo;Chong, Jong-Wha
    • ETRI Journal
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    • v.38 no.4
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    • pp.735-745
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    • 2016
  • The Paris agreement at the 21st Conference of the Parties (COP21) emphasizes the reduction of greenhouse gas emissions and increase in energy consumption in all areas. Thus, an important aspect is energy saving in buildings where the lighting is a major component of the electrical energy consumption. This paper proposes a building energy management system employing visible light communication (VLC) based on LED lighting. The proposed management system has key characteristics including personalization and localization by utilizing such VLC advantages as secure communication through light and location-information transmission. Considering the efficient implementation of an energy-consumption adjustment using LED luminaires, this paper adopts variable pulse position modulation (VPPM) as a VLC modulation scheme with simple controllability of the dimming level that is capable of providing a full dimming range. This paper analyzes the VPPM performances according to variable dimming for several schemes, and proposes a VPPM demodulation architecture based on dimming-factor acquisition, which can obtain an improved performance compared to a 2PPM-based scheme. In addition, the effect of a dimming-factor acquisition error is analyzed, and a frame format for minimizing this error effect is proposed.

VLC Channel Model Considering Indirect Light (간접 조명 환경 실내 가시광 통신의 채널 모델)

  • Lee, Jung-Hoon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.38C no.8
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    • pp.706-712
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    • 2013
  • In this paper, channel modeling of VLC(Visible Light Communication) was investigated under indirect lightning circumstance which was the way that all phontons started from LED(Light Emitting Diode) were reached on the floor with NLOS paths. I supposed width(6m), depth(4m), height(2.2m) cube room circumstance for VLC communication channel and supposed that 4 LEDs were located at 2m height, which emitted photons at the direction of wall and ceiling. Channel characteristics, which were power attenuation and delayed receiving of light signal, were abstracted from receivers(PDs) which were located at 0.5m above from floor. The availability of channel was verified via BPSK based communication simulation.

A study on the nondestructive measurement of meat quality using visible light (가시광을 이용한 육질의 비파괴적 측정에 관한 연구)

  • Maeng, Gab-joo;Lee, Young-Woo
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2009.05a
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    • pp.248-250
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    • 2009
  • In order to know the characteristics of meat quality, we performed experiment using optical method. The characteristics of meat quality was measured by using spectrum analysis and we can obtain the meat quality by experiment value of distribution of meat and fat.

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A study on the short-range underwater communication using visible LEDs (근거리 수중통신을 위한 가시광 LED 적용에 관한 연구)

  • Sohn, Kyung-Rak
    • Journal of Advanced Marine Engineering and Technology
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    • v.37 no.4
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    • pp.425-430
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    • 2013
  • Robust and high speed underwater communication is severely limited when compared to communications in terrestial. In free space, RF communication operates over long distances at high data rates. However, the obstacle in seawater is the severe attenuation due to the conducting nature. Acoustic modems are capable of long range communication up to several tens of kilometers, but it has low data-rate, high power consumption and low propagation speed. An alternative means of underwater communication is based on optics, wherein high data rates are possible. In this paper, the characteristics of underwater channel in the range of visible wavelength is investigated. And the possibility of optical wireless communication in underwater is also described. The LED-based transceiver and CMOS sensor module are integrated in the system, and the performance of image transmission was demonstrated.

Two Kinds of Hybrid Localization System Design Techniques Based on LED IT (LED IT 기반의 두 가지 하이브리드 측위 시스템 설계 기법)

  • Lee, Yong Up;Kang, Yeongsik
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.38C no.2
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    • pp.155-164
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    • 2013
  • Two design techniques for more accurate and more convenient hybrid positioning system with visible light communication (VLC) and ad-hoc wireless network infrastructure are proposed, in order to overcome the problems of high estimation error, high cost, and limited service range of the conventional positioning techniques. First method is based on a non-carrier VLC based hybrid positioning technique for applications involving of low data rate optical sensing and narrow-range visible light reception from transmitter, and long-range positioning. The second method uses a 4 MHz carrier VLC-based hybrid positioning technique for a high data rate optical sensing and wide-range visible light receiving from transmitter, and mid-range positioning applications. In indoor environments with obstacles where there are long-range 7731.4cm and mid-range 2368cm distances between an observer and a target respectively, the hybrid positioning developed with two design techniques are tested, and the proposed system is verified and analyzed in this paper.

Degradation of Chlorinated Hydrocarbons via a Light-Emitting Diode Derived Photocatalyst

  • Jo, Wan-Kuen;Lee, Joon Yeob
    • Environmental Engineering Research
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    • v.18 no.1
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    • pp.21-28
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    • 2013
  • In this study, the applicability of visible light-emitting-diodes (LEDs) to the photocatalytic degradation of indoor-level trichloroethylene (TCE) and perchloroethylene (PCE) over N-doped $TiO_2$ (N-$TiO_2$) was examined under a range of operational conditions. The N-$TiO_2$ photocatalyst was calcined at $650^{\circ}C$ (labeled N-650) showed the lowest degradation efficiencies for TCE and PCE, while the N-$TiO_2$ photocatalysts calcined at $350^{\circ}C$, $450^{\circ}C$, and $550^{\circ}C$ (labeled as N-350, N-450, and N-550, respectively) exhibited similar or slightly different degradation efficiencies to those of TCE and PCE. These results were supported by the X-ray diffraction patterns of N-350, N-450, N-550, and N-650. The respective average degradation efficiencies for TCE and PCE were 96% and 77% for the 8-W lamp/N-$TiO_2$ system, 32% and 20% for the violet LED/N-$TiO_2$ system, and ~0% and 4% for the blue LED/N-$TiO_2$ system. However, the normalized photocatalytic degradation efficiencies for TCE and PCE for the violet LED-irradiated N-$TiO_2$ system were higher than those from the 8-W fluorescent daylight lamp-irradiated N-$TiO_2$ system. Although the difference was not substantial, the degradation efficiencies exhibited a decreasing trend with increasing input concentrations. The degradation efficiencies for TCE and PCE decreased with increasing air flow rates. In general, the degradation efficiencies for both target compounds decreased as relative humidity increased. Consequently, it was indicated that violet LEDs can be utilized as energy-efficient light sources for the photocatalytic degradation of TCE and PCE, if operational conditions of N-$TiO_2$ photocatalytic system are optimized.

A Study on Frequency Response in LED-LED Communication (LED-LED 간의 통신을 위한 주파수 특성 연구)

  • Park, In-Jung;Lee, Kyu-Tae
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.12 no.1
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    • pp.115-122
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    • 2012
  • In this paper, we demonstrate that indoor wireless optical communication is possible with lighting LEDs without a photo diode or a solar cell. A LED is used for both light emitting and light signal detection. This scheme is very useful because transmission is possible without any additional communication systems. In experiments, wireless optical communication will be carried out at a higher signal frequency of 5MHz using a lighting LEDs with both light emitting and light detection characteristics in the future.

A STUDY ON THE SHEAR BOND STRENGTHS OF VISIBLE LIGHT-CURED GLASS IONOMER CEMENT WITH SEVERAL LIGHT-CURING UNITS (수종의 광중합기를 이용한 교정용 광중합형 글라스 아이오노머 시멘트의 전단 결합 강도에 관한 연구)

  • Kim, Min-Soo;You, Seoung-Hoon;Kim, Jong-Soo
    • Journal of the korean academy of Pediatric Dentistry
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    • v.34 no.1
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    • pp.81-90
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    • 2007
  • The purpose of this study was to assess the effect of light-tip distance on the shear bond strength of a visible light-cured glass ionomer cement(Fuji Ortho LC ; GC, Japan) cured with three different light curing units : a halogen light(Elipar Trilight ; 3M ESPE, Seefeld, Germany), a Light Emitting Diode (LED, Elipar Freelight2 ; 3M ESPE, Seefeld, Germany) and a plasma arc light (Flipo ; LOKKI, France). 1. When used at a distance of 0mm from the bracket, the three light curing units showed no statistically different shear bond strengths. At distance of 3 and 6mm, no significant differences were found between the halogen and plasma arc lights, but both had significantly higher shear bond strengths than the LED light. 2. The halogen light and plasma arc light showed that no significant differences in bond strength were found among the three distances. Using the LED light, a greater light-tip distance produced significantly lower shear bond strengths.

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Preliminary study on the visual sensitivity of Oreochromis niloticus using LED light source for the aquaculture development in Uganda

  • Esther Kagoya;Kyoungmi Kang
    • Fisheries and Aquatic Sciences
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    • v.26 no.8
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    • pp.514-523
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    • 2023
  • The visible threshold of Oreochromis niloticus responded to high light intensity under short wavelengths, whereas the response to low light intensity under long wavelengths was low, with a minimum visual threshold of 574 nm of LED lights. Movement distance of O. niloticus was dropped at 31℃ and increased abnormally at 37℃ under natural light. Comparing movement distance under red (622 nm) and green (518 nm) lights of LED, movement distance and swimming speed under red and green lights were higher than under natural light. However, the movement distance decreased rapidly at 31℃ under red light and lowest at 33℃ under green light. After that, there was a tendency to adapt to high water temperatures gradually. Consequently, red and green lights may be recommended for O. niloticus's aquaculture because the red and green lights have a positive effect on growth performance, survival rate, and metabolism, as shown in previous studies. It is necessary to control the water temperature below 32℃ because abnormal behavior above 32℃ revealed under red and green LED lights and natural light.

Preparation of UV Curable Anti-Glare Coating Films Using Micrometer-Sized Silica Particles (마이크로미터 크기의 실리카 입자를 이용한 UV 경화형 눈부심 방지 코팅 필름 제조)

  • Kim, Tae Hyoung;Song, Ki Chang
    • Korean Chemical Engineering Research
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    • v.59 no.2
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    • pp.165-173
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    • 2021
  • Anti-glare (AG) coating films are applied to various display fields such as liquid crystal displays, LED lighting, and touch panels. In this study, micrometer-sized silica particles were added as fillers in the UV-curable coating solutions to provide anti-glare effect. During this process, the effects of the particle size, content, stirring time, and mixing ratio of silica particles of different sizes were investigated on the haze values and visible light transmittance of the coating films. As a result, as the size of the silica particles increased and the content of the silica particles increased, the haze values increased, but the visible light transmittance decreased. On the other hand, the stirring time did not significantly affect the haze value and transmittance of coating films. In addition, as the mixing ratio of large-sized silica particles increased, the haze value increased, but on the contrary, the visible light transmittance decreased.