• ETRI Journal
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• v.24 no.5
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• pp.405-408
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• 2002

In this paper, we discuss recovery schemes for errors occurring when image data encoded with variable length coding (VLC) is transmitted through additive white Gaussian noise (AWGN) and multiple-access interference in direct sequence code division multiple access (DS/CDMA) systems. VLC such as JPEG is so sensitive to channel errors that severe degradation in decoded images occurs even if only one or two bits have errors. This is due to the loss of synchronization at the image decoder. We propose a resynchronization scheme using a power allocation method in wireless DS/CDMA transmission. Through simulation, we know that the proposed method has a more robust resynchronization capability and higher objective and subjective quality than the conventional method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.13-14
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• 2012

Than fluorescent lamps or light bulbs, long life, small power consumption and to the development of modern technology, LED (Light Emitting Diode) devices have the advantage of easy control. For these reasons, using the LED device, lighting has been widely used. LED using optical fiber technology using LED lighting technology with the development of wireless communication technology is attracting attention again. Using LED lights this study analyzed the performance of the technology transfer and implementation of the information transmission system of the visible light communication using LED lighting of the White Visible Light Communication (VLC) based PC module transmitter and receiver modules. Has made a system that can transmit information more than the value of the initial distance ~ 50cm, depending on the presence or absence of the lens, in order to increase the efficiency of the LED modules with different efficiencies that could confirm the performance of the implementation of the research, analysis, and application methods. and about the possibility that you want to check.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.1
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• pp.51-56
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• 2013

In this paper, we had design the module of the LED-based media transmission mechanics visible light communication system. To implement the media transmission system through visible light communication transmitter, receiver module the using high brightness, we proposed visible light communication system to implement communication distance of up to a maximum transmitter-receiver distance using a variable PD sensor to the receiver and 1~12 the LED light-emitting device to the transmitter. It was increased efficiency of approximately 20% by measuring the performance during lens wearing or not wearing on the LED module to improve the efficiency of the media transmission system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.1
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• pp.181-187
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• 2012

LED is just a semiconductor which can produce light. Currently, there are active research works on LED lighting technologies according to the growth of energy-saving environmental industry. Especially, LED communication is one of the active research works in these fields. In this paper, we design a LED communication-based PC-PC transmission system. A transmission circuit system(transmitter) using LED and a receiving circuit system(receiver) using PD(photo detector) and Op-amp are designed, respectively. The experiments for the designed system are performed as follows. One computer is connected at the end of transmitter and receiver, respectively, and text files are transmitted by using text transmission programming. In this experiment, we test the performance with various baud rates, LED colors, transmission ranges.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.15-16
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• 2012

General lighting will be replaced into LED due to the high efficiency, low power consumption, long life than conventional light, moreover, since it is a basically semiconductor device that can convert the electric energy to visible light at a very high speed, using these characteristics can be performed communication modulation via the high-speed ON-OFF switching. Recently, visible light communication (VLC: Visible Light Communication) technology is received attention and there have been many researches. This paper is implemented media signal transmission by combining LED with VLC, a transmitter used the LED light-emitting device and receiver used an infrared sensor. In order to increase the efficiency of the communication system to improve the existing LED visible light communication driver of power conversion efficiency and thermal issues that is applied to the visible light communication in order to improve the speed of transmission media to research a new way of LED driver.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.656-659
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• 2017

In this paper, we propose a digital method for transmitting audio signals using LED visible light communication system. In the proposed method, we compare the method for transmitting audio signal in analog signal and the method for transmitting by digital signal. When amplifying the audio sound and transmitting the analog signal using the LED visible light communication, attenuation corresponding to the transmission distance occurs, and there is a disadvantage that it is noisy. In order to overcome this, we propose a method for transmitting digital audio signals. The proposed method has the advantage of reducing the influence of noise, but it turned out that it is affected much by the LED blinking speed. Various methods to overcome this need to be continuously studied.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.8
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• pp.905-910
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• 2010

In this paper, visible light communication(VLC) system modulated by a switching driver circuit of lighting light emitting diode(LED), not only for illumination but also for optical wireless communication, is implemented. Presented system could overcome the drawbacks of prior linear modulation technique such as low efficiency, heat generation, and limits to realization of high power lighting LED. Experimental results from the realized digital audio system are presented to confirm the superiority of the proposed circuit. Our prototype achieves a transmission data rate of 10 Mbps with a radius of 1.5 meters using 20 W output power, and the signals were detected successfully.

• Journal of Satellite, Information and Communications
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• v.7 no.3
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• pp.63-68
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• 2012

The VLC (visible light communication) system is communication technology using visible rays (RGB) that come out in LED device. It is energy curtailment effect and possible in ubiquitous network service applications. Also, VLC system has the above advantage about that the communication throughout the whole room is enabled by high power lighting and lighting equipment with white colored LED which are easy to install and have good outward appearance. However, the signal detection performance for the receiver near the network of transmitter boundary is severely degraded and the transmission efficiency decreased due to the influence of the interference signal from the adjacent networks. In this paper, we propose an interference mitigation method with optical relay and optical beamforming scheme in VLC systems, and evaluate the reception performance. For the system BER, the proposed system demonstrates the performance enhancement compared to the not using the optical relay and optical beamforming scheme, and SNR performance gain and higher channel capacity is achieved.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.8
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• pp.713-718
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• 2013

In this paper, additional data transmission scheme was proposed based on SSB-OFDM Communication system which was know as efficient technique for bandwidth, because it used only single side band instead of double side band. When sending additional data which should be well spreaded for low power characteristics and error robustness. Gold code was selected for spreading code because it has excellent low-cross correlation characteristics. Through computer simulation, the validity was proved that proposed system is well worked with SSB-OFDM system.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.1
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• pp.79-85
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• 2016

Recently, visible light communication(VLC) is being actively researched as green wireless communication services are drawing attention. Currently, VLC mostly uses LED for transmission and PD(Photo Diode) for receiving. However, this kind of system has limited applications. Therefore, we design and propose in this paper, a LED-to-LED two way VLC system that doesn't use PD(Photo Diode). This system has the following features and contributions. First, this system uses just LED at both transmitter and receiver with analog switch, Second, this system support both one-way communication and two way communication together. One way communication can support multi-hop communication. The performance evaluation of the proposed system is conducted at a place with standard light. We test the success or failure of one way communication by changing distance and baud rate while test the success and failure of two way communication by changing distance. We expect that the proposed LED-to-LED system in this paper can be applied for various application fields.