• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.533-535
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• 2018

In the 21st century, in which the accident rate is rapidly increasing in proportion to the development of automobiles, In order to reduce the number of accidents, this paper was written for the convenience of the elderly people with disabilities and the handicapped. When a driver's safety accidents and various signals are transmitted through a smart phone by voice, the voice signal is processed as a video signal through the rear LED pannel of the vehicle, so that an urgent situation or a current state can be clarified It is also possible to use the local area network as a billboard and I would like to propose a study to show the advertising effect and current traffic situation.

• Journal of Sensor Science and Technology
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• v.21 no.6
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• pp.429-433
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• 2012

In this paper, we reduced the optical noise interference in a visible light communication system using two color LEDs. In the transmitter, the original and the inverted signals of the transmitted data modulated a red LED and a blue LED, respectively. In the receiver, a differential detector which is composed of two photodetectors and an optical red filter detected the mixed signal radiated from the two LEDs. In an environment that the optical noise from a fluorescent lamp exists, the signal-to-noise ratio in this system was improved by about 20dB compared to that in the conventional system which uses a single LED and a single photodetector.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2001.11a
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• pp.153-158
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• 2001

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.180-187
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• 2013

In this paper, we propose a LED communication based multi-hop audio data transmission network system. The main contribution and features of the proposed system are as follows. First, the contribution of this research is to develope the LED communication based multi-hop transmission network system which can transmit audio data signal with long distance via multi-hops. Second, the developed system has the following features: In transmitter, audio data is transmitted after encoding with S/PDIF format via a general LED. The relay receives digital audio signal by using photo diode and then transmits the signal to receiver after error checking and amplifying. The receiver receives the encoded audio data via photo diode and then converts to analog audio signal by using decoding and amplifying. The performance evaluation of the proposed system is conducted in the laboratory with fluorescent light source. The results of the performance evaluation confirm that the system can provide high quality audio transmission from transmiter to receiver via multi-hop relays in a long distance while we can see there are differences in the transmitted audio quality according to the used LED colors.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.4
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• pp.484-492
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• 2015

This paper proposes a PWM phase-shift circuit to make that the LED lighting system distributes the channel currents evenly for any number of LED strings by generating evenly phase-shifted PWM signals for multiple LED driver ICs. The evenly distributed channel currents reduce the peak current, the decoupling capacitor size, and EMI noise. The PWM phase-shift circuit makes an arbitrary degree of PWM phase-shift by using a resistor and a capacitor. It measures the RC delay once. It reduces the number of external resistors and capacitors by providing zero and 180 degree phase-shift modes requiring no resistor and capacitor. An LED driver IC with the PWM phase-shift circuit was fabricated with a $0.35{\mu}m$ BCDMOS process. The PWM phase-shift circuit receives a PWM signal of 50 Hz~20 kHz at $f_{CLK}=450kHz$ and it generates a $0{\sim}360^{\circ}$ phase-shifted PWM signal with $R=0{\sim}1.1M{\Omega}$ at C=1 nF and $f_{PWM}=1kHz$. The measured phase errors are 1.74~3.94% due to parasitic capacitances.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.12
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• pp.109-117
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• 2015

In this paper, we proposed error-reducing method to source or measure a current or voltage for LED in the I-V characteristic analysis system using a digital signal processor (DSP). this method has the advantage of reducing a non-linear circuit error and random error. random error can be reduced using recursive averaging technique and non-linear circuit error can be reduced using 2rd polynomial regression calibration parameters fitting with measured sample data. it corrects measured error of IR, VR, VF1, VF2, VF3 of LED using calibration parameters. experimental results show that can be performed with about 0.017~0.043% accuracy.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.1
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• pp.63-67
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• 2015

White light-emitting diode (WLED) is growing interest in using both illumination and communications. This paper reports visible light communication (VLC) composed of a super bright white light-emitting diode, low cost commercial photo-diode and a Fresnel lens. LED driver is consisted of the power MOSFET and MOSFET driver that switches the LED on and off. The modulation bandwidth of the LED used was determined to be 8 MHz. However, it was possible to communicate up to 1 Mbps under illumination of 500 lx because of the weak signal power and a low spectral sensitivity of the SHF213 as a PIN photodiode. In order to enhance the system bandwidth, the LED light was focused on the PIN photodiode by use of the Fresnel lens. As a result of that, visible light link was operated up to modulation bandwidth of the LED. The signal to noise ratio can be improved by 40 dB using an optical concentration at the receiver.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.9
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• pp.787-794
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• 2012

The visible light communication is considered as a next generation communication technology, when utilizes LED and PD for communication. Since it is easy to provide LOS communication environment along with cheap deployment cost, the positioning system based on VLC has been actively studied. However, the existing positioning system using VLC requires a complex computation and an additional deployment cost due to sensors for example. In this paper, we propose a new positioning system based on VLC which does not require additional complexity and the cost. In addition, the procedure for operating LED panels for positioning and the recognition schemes of pilot signal are proposed. The performance of recognition schemes of pilot signal is analyzed through the computer simulations.

• Smart Media Journal
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• v.6 no.2
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• pp.26-32
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• 2017

In this paper, we implement a signal-detecting electric circuit based LED lighting control system which is essential in NUI technology using EPIC converting surrounding earth electric field disturbance signals to electric potential signals. We used signal-detecting electric circuits which was developed to extract individual signal for each EPIC sensor while conventional EPIC-based development equipments provide limited forms of signals. The signals extracted from our developed circuit contributed to better performance as well as flexiblity in processes of feature extracting stage and pattern recognition stage. We designed a system which can control the brightness and on/off of LED lights with four hand gestures in order to justify its applicability to real application systems. We obtained faster pattern classification speed not only by developing an instruction system, but also by using interface control signals.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.717-718
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• 2013