• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.10
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• pp.834-840
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• 2012

The use of ranging sensors on automobiles is becoming common with the desire of traffic safety by providing drivers the information of the relative distance between the vehicles. In this paper, the LED visible light ranging system different from the conventional ranging systems using the RF signal is investigated. For such a system, we propose a novel ranging algorithm which combines the time-of-flight (TOF) with the CDMA technology. Via the CDMA technology, the TOF ranging system can accurately distinguish the desired ranging signal from the visible light interferences of the neighbor vehicles. In addition, the proposed system can also overcome the light noise from other luminaries, i.e. sun-light, traffic-light, and so on. The simulation results show that the CDMA-based LED ranging system has a significant improvement for the ranging accuracy compared with the case without employing the CDMA.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.797-798
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• 2012

The purpose of this study to embody LED visible light communication visual signal delivery system based on TFT-LCD module and to analyze a performance for digital signals. LED lighting enables to transmit data through light, to embody visible light communication, and to control lights in different wavelengths according to LED materials and structural materials. In this study, we aim to create a transmitting and receiving sensor that has implemented LED and visual sensors to LED efficiency and existing TFT-LCD module so as to estimate and indicate a communication distance and to find out application methods and problems. Also, by implementing TFT-LCD technology and next-generation LED visual communication technology, this study aims to check the possibility of technological realization by applying them to various means of communication including ubiquitous communication.

• Journal of IKEEE
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• v.22 no.2
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• pp.316-323
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• 2018

In this paper, we newly introduce the three-level byte-inversion transmission method for preventing LED flicker in visible light communication (VLC). The VLC transmitter sequentially sends the original signal and the inverted signal in byte units using a three-level LED modulator. The average optical power of the LED is kept constant during data transmission, thus flicker-free. In the VLC receiver, the original data is easily recovered using a simple comparator. This structure is very simple because additional clock or carrier is not required for flicker prevention. The developed flicker prevention scheme could be very useful for constructing the flicker-free indoor VLC system in low cost.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.6
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• pp.852-857
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• 2010

In this paper, we proposed and demonstrated an indoor visible-light communication system using an array of light-emitting diodes (LEDs). The main idea is based on that the LEDs can be used not only for lighting but also for free-space optical communications. Because LEDs offer advantageous properties such as high brightness, reliability, lower power consumption and long lifetime, the indoor visible-light communication systems are going to provide high quality of service by the high radiation power of the LED lighting. Prototype of simplex channel for audio and the full-duplex channel for text message were developed. Results indicates the viability of creating inexpensive free-space optical communication transceivers that might be embedded in commercial light products to supports indoor wireless networking.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.11
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• pp.755-762
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• 2014

In recent year, along with the rapid development of LED technology, many applications using LEDs with Visible Light Communication(VLC) have been researched. Since it is easy to provide LOS communication environment along with cheap deployment cost, the indoor positioning system based on VLC has been actively studied. In this paper, we propose an accurate indoor positioning algorithm using a stereo image sensor and white-light LEDs with the visible light communication. Indoor white-light LEDs are located at the ceiling of a room and broadcast their position information by VLC technology. Mobile receiver with stereo image sensor receives LED position information by VLC and estimates its position and angle information. Simulation results are given to show the efficiency of proposed indoor positioning algorithm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.1
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• pp.42-46
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• 2011

Light can be divided into ultraviolet rays, visible rays, and infrared rays depending on the wavelengths. Visible rays with specific wavelength are those predominantly used for would treatment. Especially low level laser irradiates into cells, effectively stimulating cellular tissues and activating cellular function. This study was intended to verify the effect of white LED irradiation therapy on wound recovery in animal tests by applying white LED irradiator, which was independently designed and developed to emit beams of similar wavelength to that of a laser. The designed LED Irradiator was used to find out how white LED light source affected the skin wound of SD-Rat(Sprague-Dawley Rat). We divided the participants into two groups; white LED irradiation group which was irradiated 1 hour a day for 9 consecutive days, and none irradiation group. The results showed that the study group had lower incidence of inflammation and faster recovery, compared with the control group.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.668-670
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• 2018

Recently, VLC(Visible Light Communication), which is a technology to communicate wirelessly by carrying information in lights based on LED, is getting attention. If we use the VCL, we don't need to receive authorization because it uses the existing industrial infrastructure(LED infrastructure) and frequency band together and there is the little possibility of interference and it has a high level of security by removing visible light in a portion where data transfer is not required. These are the advantage of VCL. In this paper, we study the traffic and signal system based on Visible Light Communication with consideration for these advantages.

• 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.

• 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.

• Journal of Sensor Science and Technology
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• v.23 no.4
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• pp.238-244
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• 2014

In this paper, we introduce a new passive transponder that operates without external power in a visible light identification system. The transponder consists of a solar cell, a photodiode, a microprocessor, and a visible LED. When a reader sends light to the transponder, the solar cell generates current from the reader light and supplies power to the other elements in the transponder. At the same time, the photodiode detects the pulse in the reader light and initiates a microprocessor to generate and send a responding light to the reader. In experiments, we realized a passive transponder using a solar cell that operated at a distance of 1m without external power.