• Title, Summary, Keyword: visible light

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A STUDY ON THE ROUGHNESS OF THE VISIBLE LIGHT CURED COMPOSITE RESINS (가시광선(可視光線) 중합형(重合型) 복합(複合)레진의 표면조도(表面粗度)에 관(關)한 연구(硏究))

  • Lee, Myung-Jong
    • Restorative Dentistry and Endodontics
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    • v.16 no.2
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    • pp.197-212
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    • 1991
  • The purpose of this study was to roughness on the polished surface of visible light composite resins and was to observe the polished surfaces under Scanning Electrom Microscope(ISI DS 130 AKASHI Co. JAPAN). The surface roughness tester(Surfcom 700A Seimtsu profilometer Tokyo, Japan) was used to measure roughness of polished surfaces. In this study, 5 brands of visible of composite resins were examined, Pyrofile light bond Anterior Lite fil anterior Photo clearfil anterior & posterior Palfique light Anterior and posterior Silux Anterior. White point, Silicure point, Super snap Sof-Lex medium disk as cutting instrument, and celluloid matrix were used. The results obtained were as follows. 1. The Celluloid matrix produced the smoothest surfaces. 2. The surfaces made by Soflex medium disk was smoother than the surfaces made by any other polishing instruments. 3. The values of surface roughness made by White point, Silicon point and Super snap were similer. 4. Palfique light (AP) visible light composite resin showed the smoothest surface after polishing with Silicone point, Super snap disk and Soflex mediuem disk in all tested materials.

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A Passive Transponder for Visible Light Identification Using Ultrasonic wave (초음파를 이용한 가시광인식 수동형 트랜스폰더)

  • Lee, Seong-Ho
    • Journal of Sensor Science and Technology
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    • v.26 no.3
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    • pp.192-198
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    • 2017
  • In this paper, we newly developed a passive transponder for visible light identification (VLID) using ultrasonic wave. The solar cell in the transponder receives the reader light and generates current for supplying power to the transponder circuit. At the same time the solar cell detects the interrogating signal in the visible light from the reader. The transponder recognizes the interrogating signal and generates the responding signal using ultrasonic wave. In experiments, we used 40 kHz ultrasonic wave for the responding signal from the transponder. The maximum read distance was about 3.4 m when the transponder was exposed to the reader light of 24W LED array.

Flicker-free Visible Light Communication Using Three-level RZ Modulation

  • Lee, Seong-Ho
    • Journal of Sensor Science and Technology
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    • v.29 no.2
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    • pp.75-81
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    • 2020
  • We introduce a new visible light communication (VLC) method in which three-level return-to-zero (RZ) modulation is used for flicker-free transmission. In the VLC transmitter, the three-level RZ modulation ensures that the average optical power is constant; thus, a flicker-free light-emitting diode (LED) light is achieved. In the VLC receiver, a resistor-capacitor high-pass filter is used for generating spike signals, which are used for data recovery while eliminating the 120 Hz optical noise from adjacent lighting lamps. In transmission experiments, we applied this method for wireless transmission of an air quality sensor message using the visible light of an LED array. This configuration is useful for the construction of indoor wireless sensor networks for air pollution monitoring using LED lights.

Performance Evaluation of CT Using Visible Scintillation Light

  • Kodama, Kiyoyuki;Hashimoto, Masatoshi;Hanada, Takashi;Suzuki, Tamotsu;Ide, Tatsuya;Maruyama, Koichi
    • Proceedings of the Korean Society of Medical Physics Conference
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    • pp.464-467
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    • 2002
  • We propose the use of visible scintillation light for monitoring the X-ray CT in the gantry of a diagnostic CT for its performance test and maintenance works. We placed a disk of bare plastic scintillator disk in the gantry opening area of a helical X-ray CT. When we operated the CT, we could observe the emission of blue scintillation light from the scintillator in a dark room. Visible light was identified under all scanning conditions of diagnostic uses. As a result, we observed the direction and the spread of the incident X-ray in the scintillator. We also observed the change of the part of the scintillator where visible light was generated, and the move that took place associating with the rotation of the X-ray tube during one CT scan. On the basis of the observation, we examined the usefulness of the visible scintillation light as a convenient performance-evaluating tool as well as a maintenance tool of the CT.

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Visible Light Identification System for Smart Door Lock Application with Small Area Outdoor Interface

  • Song, Seok-Jeong;Nam, Hyoungsik
    • Current Optics and Photonics
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    • v.1 no.2
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    • pp.90-94
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    • 2017
  • Visible light identification (VLID) is a user identification system for a door lock application using smartphone that adopts visible light communication (VLC) technology with the objective of high security, small form factor, and cost effectiveness. The user is verified by the identification application program of a smartphone via fingerprint recognition or password entry. If the authentication succeeds, the corresponding encoded visible light signals are transmitted by a light emitting diode (LED) camera flash. Then, only a small size and low cost photodiode as an outdoor interface converts the light signal to the digital data along with a comparator, and runs the authentication process, and releases the lock. VLID can utilize powerful state-of-the-art hardware and software of smartphones. Furthermore, the door lock system is allowed to be easily upgraded with advanced technologies without its modification and replacement. It can be upgraded by just update the software of smartphone application or replacing the smartphone with the latest one. Additionally, wireless connection between a smartphone and a smart home hub is established automatically via Bluetooth for updating the password and controlling the home devices. In this paper, we demonstrate a prototype VLID door lock system that is built up with LEGO blocks, a photodiode, a comparator circuit, Bluetooth module, and FPGA board.

A MAC Protocol for LED visible light communications with beamforming (빔포밍 기능을 가진 LED 무선 가시광 LAN 통신을 위한 MAC 프로토콜)

  • Kim, Sung-Man
    • The Journal of the Korea institute of electronic communication sciences
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    • v.6 no.3
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    • pp.425-432
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    • 2011
  • To increase the bit rate over than 1 Gb/s in LED visible light communications, we need to reduce the multipath effect of the light in indoor environment. In this paper, we propose a MAC protocol for LED visible light wireless LAN with beamforming technique. We assumed that spatial light modulator is used for beamforming function. We use polling method since detecting another uplink channel is difficult in visible light communication. We also estimated the performance of the proposed MAC protocol.

A Study on Realization and Receiving Characteristic Analysis of Visible Light Wireless Communication System for Power Line Communications Using ATmega16 Microcontroller (ATmega16 마이크로컨트롤러를 이용한 전력선통신용 가시광 무선통신 시스템 구현 및 수신 특성 분석)

  • Yun, Ji-Hun;Hong, Geun-Bin;Kim, Yong-Kab
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.59 no.11
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    • pp.2043-2047
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    • 2010
  • This study is to solve problems of depletion of RF bandwidth frequency, confusion possibility, security that current wireless communications system have and is to confirm possibility of applying next generation network. To solve problems of current wireless communications system, visible light communications system for power line communications using ATmega16 Microcontroller is was realized and receiver property was analyzed. PLC exclusive chip APLC-485MA, Microcontroller ATmega16, 5pi bulb type LED and high flux LED, visible light receiving sensor LLS08-A1 were used for transmitter and receiver. Performance was analyzed by designed program and an oscilloscope. It was showed average 20% improved receiver rate rather than bulb type LED in the case of high flux LED through voltage change rate on communication distance and LED type of distance between 10 to 50 cm. The blue LED showed the best performance among measured LED types with above 10% of voltage decreasing rate. But As it gradually becomes more distant, the precise date was difficult to obtain due to weak light. To overcome these sort of problems, specific values such as changing conditions and efficiency value relevant to light emitting parts and visible light receiving sensor should be calculated and continuous study and improvements should also be accomplished for the better communications condition.

Korean Secondary Students' Conceptions about Visible light, Ultra Violet and Infrared Ray (가시광선, 자외선과 적외선에 대한 학생들의 개념)

  • Han, Shin;Park, Tae-Yoon;Jeong, Sophia Sun Kyung
    • Journal of the Korean Society of Earth Science Education
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    • v.8 no.1
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    • pp.35-44
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    • 2015
  • The purpose of this paper is to identify the conceptions of middle school and high school students about visible light, Ultra violet(UV) and Infrared ray(IR). We administered questionnaire 40 people of middle school 3rd students and 43 people of high school 2nd students in Gyeonggi-do. Misconceptions about visible light, UV and Ir were observed in many students. The results of study are as follows: Firstly, Many students think that it is possible to see objects without visible light. The explanations given by students for the visiblity of objects in darkness indicates a heavy reliance on personal experiences. Secondly, we have confirmed that high school students well understand the fact that the object reflects the light. However, a significant number of students exhibited an eye-centered perspective of vision. Thirdly, students had a variety of ideas about the meaning of the term UV and IR. Analysis of questionnaire data indicates that many students believe that it is possible to see objects in the presence of UV light alone.

To improve the performance of BER using the 2-step interleaving for Visible Light Communication with LEDs (LED를 이용한 가시광 통신 시스템에서 2-step 인터리빙을 통한 BER 성능 향상)

  • Lee, Jonghyun;Seo, Hyoduck;Han, Doohee;Lee, Kyesan;Lee, Kyujin
    • Journal of Satellite, Information and Communications
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    • v.10 no.2
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    • pp.46-53
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    • 2015
  • Visible Light Communication (VLC) is effective way to realize the light device and communication device using a Light Emitting Diode (LED) simultaneously. VLC has high security for Field Of View (FOV) communication area, also which is possible to transmit the high data rate using visible light. In VLC, transmitting the divided data by the RGB channels is higher data rate than transmitting the same data by RGB channels. However, it occurred the burst error by scattering and reflection of visible light which is impossible to restore that. To solve the problem, we proposed the 2-step interleaving scheme that high data rate and improve the performance of BER in VLC. The proposed system implements cyclic interleaving and convolutional interleaving that is able to be standardized the performance of RGB channels and improve the performance of BER using error correction.

Visible Light Communication with Color and Brightness Control of RGB LEDs

  • Choi, Kyungmook;Jang, Yunseon;Ju, MinChul;Park, Youngil
    • ETRI Journal
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    • v.35 no.5
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    • pp.927-930
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    • 2013
  • We propose a visible light communication system in which the color and brightness are controllable. Pulse width modulation and variable pulse position modulation (VPPM) schemes are used to control the color and brightness, respectively. A digital algorithm to decode VPPM signals is suggested and implemented. A seamless transmission is observed in a testbed experiment under various environmental conditions. The proposed scheme can be applied to emotional-lighting-based wireless optical communication.