• Title, Summary, Keyword: visible light

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Facile Synthesis of Porous TiO2 Nanopearl and Nanorice toward Visible-Light Photocatalysts

  • Lee, Jooran;Bae, Eunju;Yoon, Minjoong
    • Rapid Communication in Photoscience
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    • v.1 no.1
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    • pp.13-15
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    • 2012
  • New porous $TiO_2$ nanostructures with shapes of pearl and rice were synthesized by hydrothermal treatment of $TiO_2$-liposome nanocomposites in acid and base solutions, respectively, as identified by scanning electron microscopy (SEM), transmission electron microscopy (TEM) images and large Brunauer-Emmett-Teller (BET) surface areas. The x-ray diffraction (XRD) patterns and selected area electron diffraction proved them to be well-defined anatase crystals. Their UV-visible reflectance absorption spectra were observed to have low band gap energy (3.03 and 3.07 eV, respectively), exhibiting surface absorption band in the visible range from 400 to 600 nm. The degradation of methylene blue (MB) over the $TiO_2$ nanostructures was observed upon visible-light irradiation, which was found to be very efficient as compared with any other conventional visible-light responsive $TiO_2$ nanostructures.

Short-range Visible Light Positioning Based on Angle of Arrival for Smart Indoor Service

  • Lee, Yong Up;Park, Seop Hyeong
    • Journal of Electrical Engineering and Technology
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    • v.13 no.3
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    • pp.1363-1370
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    • 2018
  • In visible light (VL) positioning based on angle of arrival (AOA) estimation for smart indoor service, the AOA parameters obtained at the receiver has sometimes a random and distributed angle form instead of a point angle form due to the multipath transfer of the actual visible light and short positioning distance. The AOA estimation of a VL signal with a random and parametric distributed angle form may give incorrect AOA parameter estimates, which may result in poor VL positioning performance. In this paper, we classify the AOA parameters of the received VL signal into three forms according to the actual positioning channel environment and consider the short-range VL positioning method. We propose a subspace-based AOA parameter estimation technique and a data fusion method, and analyzed the proposed method by simulation and the measurement of the real VL channel characteristics.

Localization Techniques Based on Image Sensor and Visible Light Communication (이미지 센서 및 가시광 통신 기반 위치 추정 기술)

  • Le, Nam-Tuan;Ifthekhar, Md. Shareef;Mondal, Ratan Kumar;Jang, Yeong Min
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.41 no.1
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    • pp.37-41
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    • 2016
  • Localization is one of the key issues of demandable applications, especially smart services. Beside the traditional GPS based localization technique, the localization issue by visible light communications is promising market because of possibility of combining visible light communications with positioning technique for a high accurate, especially indoor localization service. This paper provides the overview and new image sensor scheme for localization issue based on visible light communication. The survey is introduced from core techniques to enhancement issues of localization. We hope these will be the essential references for the impact selection method in implementation and standardization issues.

Implementation of Portable Visible Light Receiver using USB OTG (USB OTG를 활용한 휴대용 가시광 수신기 구현)

  • Lee, Dae-Hee;Lee, Jong-Sung;Oh, Chang-Heon
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.741-743
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    • 2017
  • The visible light communication is a communication method of outputting binary data based on the illumination threshold value at the light receiving diode of the receiving unit, when the LED of the transmitting unit transmits light. However, separate receiver is necessary to receive the optical signal, there is a problem that a device not equipped with such a receiver can not utilize visible light communication. To solve this problem, this paper proposes a portable visible light receiver applicable to devices using USB OTG. Implemented portable visible light receiver converts the binary data received from the LED into a character string of ASCII code and transmits it to another device. Through data transmission experiments using smart phone confirmed that it is possible to transmit ASCII codes in the proposed method.

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Estimation Algorithm of Receiver's Position and Angle Based on Tracking of Received Light Intensity for Indoor Visible Light Communication Systems (실내 가시광 무선 통신 시스템의 수신 광도 변화 추적 기반 단말기 위치 및 수신각 추정 알고리즘)

  • Hwang, Jun-Ho;Lee, Ji-Soo;Yoo, Myung-Sik
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.48 no.3
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    • pp.60-67
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    • 2011
  • Visible light communication system transmits data by controlling light emission of LED and receives data through photo detecter, which is considered as one of strong candidates of next generation wireless communication systems. The transmission capacity of visible light communication system depends on light intensity emitted from LED, sensitivity of PD, distance between transmitter and receiver, angle of incidence at the receiver. In particular, the receiver's vertical and horizontal movement changes distance between transmitter and receiver and angle of incidence, which may degrades transmission capacity of system. In this paper, we propose an estimation algorithm of receiver's position and angle based on tracking of received light intensity for indoor visible light communication systems. The performance evaluation of proposed algorithm confirms that the estimation algorithm of receiver's position and angle is quite important for visible light communication system to improve its transmission capacity.

Efficient Data Transmission in LED-based Visible Light Communication Using Variable RGB Interleaving scheme (가변적인 RGB Interleaving을 활용한 LED 기반의 가시광 통신에서 효율적인 데이터 전송 기법)

  • Seo, Hyo-duck;Lee, Kyu-jin
    • Journal of Convergence for Information Technology
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    • v.7 no.6
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    • pp.167-172
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    • 2017
  • In this paper, we propose a variable RGB interleaving technique for efficient data transmission in LED based visible light communication system. Visible light communication systems that utilize light as a resource for data transmission are affected by the nature of light and the three primary colors of light. However, the nature of light, such as light reflection, diffraction, and superposition, causes interference of the data to be transmitted, causing burst errors in the data. Such a problem causes the BER performance of the visible light communication system to degrade. To solve these problems, this paper attempts to utilize the variable RGB interleaving technique. Through variable RGB interleaving, data burst errors can be reduced and inter channel interference in a visible light communication system can be reduced. In addition, if the proposed system is applied to meet the QoS that depends on the importance of data or the requirements of the user, it can provide QoS requested by the user and enable efficient data transmission.

A STUDY ON THE DEPTH OF POLYMERIZATION OF VISIBLE LIGHT ACTIVATED COMPOSITE RESINS (가시광선(可視光線)이 복합(複合)레진의 경화(硬化)에 미치는 효과(效果)에 관(關)한 연구(硏究))

  • Chung, Sae-Joon;Lee, Myung-Jong
    • Restorative Dentistry and Endodontics
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    • v.10 no.1
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    • pp.145-152
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    • 1984
  • The purpose of this study was to compare combinations of the four visible light irradiating appliances (Translux, Heliomat, Pluraflex HL 150, Omega) and the four visible light activated composite resins (Durafil, Heliosit, Plurafil-super, Silux) to determine the depth of polymerization of each combination. Twenty samples were made with Durafil. Five samples were polymerized for 20 seconds using Translux, five with Heliomat, five with Pluraflex HL 150, five with Omega. Twenty samples were made with Heliosit, twenty with Plurafil-super, and twenty samples with Silux. A 20-second polymerization time was applied with each of 4 visible light irradiating appliances to 5 samples of each material. Eighty samples were treated in a like manner, but polymerization was extended to 40 seconds. Depth of polymerization were measured with caliper. The results were as follows. 1) Of the two time exposures, 40-second exposure provided a significantly greater depth of polymerization than 20-second for each light with each material. 2) Durafill-Translux system showed minimum depth of polymerization, and Plurafil-Pluraflex system showed maximum depth of polymerization. 3) Visible light irradiating appliances were able to harden the resins cured by tire visible lights of other makers' apparatuses. 4) In all circumstances, depth of polymerization was between 3.0-3.8mm.

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Synthesis of Nanosized SnS-TiO2 Photocatalysts with Excellent Degradation Effect of TBA under Visible Light Irradiation

  • Meng, Ze-Da;Zhu, Lei;Ullah, Kefayat;Ye, Shu;Oh, Won-Chun
    • Korean Journal of Materials Research
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    • v.25 no.9
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    • pp.455-461
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    • 2015
  • SnS-$TiO_2$ nanocomposites are synthesized using simple, cheap, and less toxic $SnCl_2$ as the tin (II) precursor. The prepared nanoparticles are characterized using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV-Vis diffuse reflectance spectra (DRS). The XRD and TEM results indicate that the prepared product has SnS nanoparticles and a grain diameter of 30 nm. The DRS demonstrate that SnS-$TiO_2$ possesses the absorption profile across the entire visible light region. The generation of reactive oxygen species is detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). It is found that the photocurrent density and photocatalytic effect increase with the modified SnS. Excellent catalytic degradation of Texbrite BA-L (TBA) solution is observed using the SnS-$TiO_2$ composites under visible light irradiation. It is proposed that both the strong visible light absorption and the multiple exciton excitations contribute to the high visible light photocatalytic activity.

A Study on Realization of Visible Light Communication System for Power Line Communication Using 8-bit Microcontroller

  • Yun, Ji-Hun;Hong, Geun-Bin;Kim, Yong-Kab
    • Transactions on Electrical and Electronic Materials
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    • v.11 no.5
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    • pp.238-241
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    • 2010
  • The purpose of this study is to solve the problems of radio frequency bandwidth frequency depletion, confusion possibilities, and security that are in current wireless communications systems, and to confirm the possibility of applying those solutions for the next generation network. To solve the problems of the current wireless communications system, a visible light communications system for power line communication (PLC) via 8-bit microcontroller is created and the capacity is analyzed. The exclusive PLC chip APLC-485MA, an 8-bit ATmega16 microcontroller, high brightness 5pi light emitting diodes (LEDs), and the LLS08-A1 visible light-receiving sensor were used for the transmitter and receiver. The performance was analyzed using a designed program and an oscilloscope. The voltage change was measured as a function of distance from 10-50 cm. Blue LEDs showed the best performance among the measured LED types, with 0.47 V of voltage loss, but for a distance over 50 cm, precise data was not easy to obtain due to the weak light. To overcome these types of problems, specific values such as the changing conditions and efficiency value relevant to the light emitting parts and the visible light-receiving sensor should be calculated, and continuous study and improvements should also be realized for better communication conditions.

Representation of Light Spectrum using N-color Dispersion Photon Mapping (N색 분산 포톤매핑을 이용한 빛의 스펙트럼 표현)

  • Gwak, Young-Sik;Ryoo, Seung-Taek
    • Journal of The Korea Computer Graphics Society
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    • v.16 no.2
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    • pp.39-45
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    • 2010
  • The color of object is a main role that people recognize outdoor entity with its shape. We can perceive the object due to the existence of light such as direct sunlight. Light is classified by wavelength into radio, microwave, infrared, the visible region we perceive as light, ultraviolet, X-rays and gamma rays. White light is all of the colors of light combined within the visible light spectrum. When white light is separated through a prism, we see the visible light spectrum. The various wavelengths of visible light are separated into colors. In this paper, we construct white light as the seven colors of rainbow and suggest the method of N-way color dispersion photon mapping to simulate the natural dispersion phenomenon.