• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.563-565
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• 2010

LED is low power and pro-environment semiconductor element. That can be used not only as the lighting function but also for Visible Light Communication(VLC). The VLC is the communication technology that can send data by blinking a fluorescent or LED using visible spectrum. That velocity of blinking can not be usually recognized by eyesight. Visible Light Communication using LED can be used in many fields. In the field of ITS(Intelligent Transportation System), Under construction on the road, Emitting traffic signs can be applied to transfer the vehicle information. In this paper, Emitting traffic signs in addition to the VLC give information about road condition, safety distance and the lane change. We design Communication protocol to provide safety service and verify protocol by experiment.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.996-1000
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• 2010

In order to apply VLC (visible light communication) in harsh environment of nuclear power plant in-containment building, the high luminance LEDs, which are key components of the VLC system, have been gamma irradiated at the dose rate of 4 kGy/h during 72 hours up to a total dose of 288 kGy. The radiation induced coloration effect in the high luminance LED bulb made of acryl or plastic material was observed. In the VLC wireless data transmission experiment using the high luminance LEDs irradiated by high dose rate gamma-ray, the radiation induced coloration effect of the high luminance LED bulb extended the communication distance compared to non-irradiated LEDs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.9
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• pp.775-780
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• 2013

Localization, or positioning, is gaining the increasing attention of researchers around the world. The location information, especially the indoor location, is important for navigation systems, heating and air conditioning systems, illumination adjustment, humidity control, robot service, and so on. In this paper, we propose a three-dimensional indoor localization technique using visible light. The main goal of our proposed scheme is to improve the accuracy of VLC-based indoor localization by utilizing multiple VLC transmitters. The simulation results validate the performance of our proposed scheme.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.65-67
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• 2021

This thesis is to proposer a new algorithm for a position measurement system using a trilateration method through visible light communication(VLC), by light emitting diode(LED). The length from each LED to the sensor is derived, and location information is found using trilateration method based on the derived length. Unlike th existing positioning system using visible light communication, the proposed positioning system is simpler and more cost effective because it does not require communication between the transmitter and the receiver.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.4
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• pp.51-55
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• 2021

In this paper, we propose the deep learning based interference cancellation scheme algorithm for visible light communication (VLC) systems in smart building. The proposed scheme estimates the channel noise information by applying a deep learning model. Then, the estimated channel noise is updated in database. In the modulator, the channel noise which reduces the VLC performance is effectively removed through interference cancellation technique. The performance is evaluated in terms of bit error rate (BER). From the simulation results, it is confirmed that the proposed scheme has better BER performance. Consequently, the proposed interference cancellation with deep learning improves the signal quality of VLC systems by effectively removing the channel noise. The results of the paper can be applied to VLC for smart building and general communication systems.

• Journal of IKEEE
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• v.22 no.3
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• pp.742-746
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• 2018

In this paper, we implemented a VLC(Visible Light Communication) system capable of transmitting/receiving data on a 30MHz clock based on On/Off keying modulation/demodulation. The data rate of the implemented system can be verified by functional verification of VLC channel composed of LED/photodiode driver and VLC transmitting/receiving signal of Tx/Rx platform. But, In the experimental results with the VLC transmitting/receiving for combined module, the maximum transmission rate was measured at 15 MHz. Therefore, we describe the problems that can occur when implement the VLC system using the LED module with output power of 15W or more and propose ways to improve it.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.6
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• pp.91-97
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• 2018

This paper presents implementation possibilities of digital IoT doorlock systems via VLC(Visible Light Communication)'s color grid. The color grid-based VLC modulation scheme which are discussed in this paper utilize the straightness of light and abundant frequency resources which are the properties of the light. Performance results in this paper are compared to that of conventional modulations with Bit Error Rate (BER) and Signal to Noise Ratio (SNR) simulations. With respect to a channel model, the proposed modulation schemes select the nearest Line Of Sight (LOS) except Non Line Of Sight (NLOS). Experiments in this paper show error rates of received symbols by changing power dB at a distance of 3m between Tx and Rx in an indoor environment. Through performance results and experiments, this paper demonstrates superiority of the proposed color grid-based modulation schemes.

• 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.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.9
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• pp.787-796
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• 2013

In this paper, the visible light communication (VLC) techniques based on the carrier modulation are considered in order to realize the VLC application service that has the functions of the high speed optical sensing and the wide range reception from VLC transmitter. The VLC hardware circuits based on the 32.768 kHz low frequency carrier and 4 MHz high frequency carrier are designed and implemented respectively, and the signal waveform generated from the implemented circuits are observed. In addition, various performance experiments are done with the prototypes.