• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.266-267
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• 2004

LED를 이용한 차량용 signal lamp를 구현 하였다. 가변적인 전원전압 및 온도조건에서도 일정한 광량을 유지할 수 있도록 하였으며, 한편 단위 LED 사이의 특성 차이로 인한 밝기의 불균일성을 줄일 수 있도록 하기 위하여 펄스폭 변조를 응용한 회로를 적용하였다.

• Journal of Sensor Science and Technology
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• v.25 no.3
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• pp.189-195
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• 2016

In this paper, we newly introduce a visible light communication (VLC) repeater using the LED array in an LED lamp. The LED array is used for a light source in the repeater, which radiates light both for illumination and data transmission. A VLC repeater is made by adding some electronic circuits to the LED array including a photodetector, a demodulator, and a modulator. The repeater is installed on the ceiling of a room like a conventional LED lamp, receives the VLC signal from an arbitrary transmitter, recovers data, and radiates the signal to wide area in the room. We used a carrier frequency of 100 kHz for the uplink from a transmitter to the repeater, and 500 kHz for the downlink from the repeater to a receiver. The repeater is useful for increasing the transmission path to wide area over the obstacles that may exist between VLC transmitters and receivers.

• Journal of Sensor Science and Technology
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• v.24 no.5
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• pp.342-347
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• 2015

We introduce an indoor broadcasting system using light-emitting diode (LED) lamps coupled with a 220 V power line. Two couplers connected to the power line constitute a power line communication (PLC) link. The transmission path from an LED lamp to a photodetector forms a visible light communication (VLC) link in free space. When the LED lamp is coupled to the power line, a composite PLC-VLC link is formed, making it possible to transmit a VLC signal beyond line-of-sight. In experiments, a 4 kHz analog signal modulated with a 100 kHz carrier was sent to the power line by a PLC coupler, and LED lamps coupled to the power line detected the signal and radiated it to multiple VLC receivers in the room. This configuration is useful in expanding an indoor VLC sensor network to adjacent rooms or constructing a voice broadcasting system in a building or apartments with existing power lines.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.7
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• pp.1261-1267
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• 2007

Although LEDs have been used in various applications with improving the brightness and luminous efficacy, the electrical and optical characteristics of high power LED varies at different temperature and starting time. In this paper, optimal heat sink and apparatus design were conducted using IR camera and ICEPAK on the LED bulb consisting with fourteen LED array. The temperatures of heat sink and LED device of the designed LED bulb without cooling pan were $74^{\circ}C\;and\;96.8^{\circ}C$, respectively, showing in good themal characteristics. For high efficiency driving circuit of LED array adopted optimal heat sink design, driving circuits of constant voltage and current circuits were suggested and fabricated. As a result the efficacy of all driving circuits showed more than 20 lm/W. Also, the constant current circuits are suitable for signal lamp, hallway lamp, and flash lamp having short operating time(about 30 min). On the other hand, a reading light and indoor lamp having long operating time can be controlled by constant voltage circuit.

• Fashion & Textile Research Journal
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• v.20 no.1
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• pp.101-107
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• 2018

The purpose of this study is to develop the electroconductive textiles based on polyurethane(PU) nanoweb and to explore that it is applicable to smart clothing. The electroconductive textiles developed by coating 2.0 wt% aqueous dispersed non-oxidized graphene paste on the surface of PU nanoweb. The fabricated electroconductive nanoweb was applied as a transmission line to connect the LED lamp, and the brightness of the LED lamp was measured to confirm its performance. The nanoweb transmission line was fixed by two methods(seam sealing tape, embroidering) to connect the LED lamp and AA batteries. The results as follows, the brightness of the LED lamp fixed with seam sealing tape was about 82 lux, and which fixed with embroidering was about 57 lux. It represents that the nanoweb transmission line which fixed with the seam sealing tape has better electrical signal transmitting because the lux value higher than the one fixed by embroidering. In order to compare the performance of the nanoweb transmission line and the metal wire, we connected the LED lamp with copper wire. The brightness of copper wire connected LED lamp was about 193 lux. Although the electrical signal strength of the nanoweb transmission line was weaker than the copper wire, it was reachable to operate LED lamp. The results of this study will provide a basic data to develop the textile based electronic devices, and conducting wire for smart clothing.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.5
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• pp.643-648
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• 2011

In this study, SMPS driven LED traffic signal light for Large-scale traffic such as railroad and airport was designed and its electrical and EMI characteristics were measured. The output current of the LED module driven by SMPS was 1.67A for AC and DC input voltage over 10V. The conducted emission measured over 0.15~30MHz frequency range was lower than the allowed quasi-peak and average level, and the radiated noise measured over 30~1000MHz frequency range showed $23.96dB{\mu}V/m$ at 59.96MHz.

• Journal of Industrial Technology
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• v.25 no.B
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• pp.183-188
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• 2005

Instead of the incandescent lamps the LED lamps have been used on the traffic signal lamp with the advantages of small loss, no lens and long life. In this paper, we have compared three kinds of the LED controller structures and showed the LED array decision methods. We studied the temperature characteristics on LED and the temperature compensation network. The experimental results showed that the electrical characteristics of three kinds of the LED controller structures were different each other. We concluded that the temperature compensation is the important technique, the best compensation network has the ${\pm}10%$ variation for the luminous intensity.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.11
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• pp.690-695
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• 2014

In this paper, we develop a explosion-proof LED lighting (Ex circuit) circuit of Explosion-proof LED Signal Lamp (Ex LSL) to utilize the core module of the explosion-proof Local Control System (Ex LCS) for offshore plant applications. And then analyzed its electrical, optical and thermal characteristics. Ex circuit was applied input voltage from AC/DC(12~254) V. In this experiments, stable light-on characteristics were confirmed by eyes for the every input voltages with min. 78,462 and max. $517,975cd/m^2$ of luminance. also Output current and output luminance was made proportional. Because the measured maximum surface temperature of Ex circuit was $54.23^{\circ}C$ at AC 48 V, Ex circuit was rated with T6 of temperature class. Finally, Ex circuit was shown stable light on characteristics under the $-50^{\circ}C$ and $60^{\circ}C$ during 12 hours of test period.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.348-350
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• 2006

Currently the indication method of the traffic signal light which is established in our country displays each "red, yellow, green" using the brightness LED signal light. In this paper, one LED circular arrangement replaces the Current indication method of the traffic signal light using two color LED. Also the blinking signal function of present time uses the MCU of AVR series and it is embodied with magnification and abridgment of the circular arrangement for recognizing easily far away. The signal light indication method which is proposed will be able to substitute the signal light of 3 colors with 1 signal light with economic profit presented the reform measure of energy efficiency improvement together.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.9
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• pp.15-22
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• 2013

A new LED lamp driving technology with a charge pump instead of a conventional DC-DC converter is proposed. The proposed driving technology is used to control the LED lamp with digital dimming. The power loss in the zener diodes is reduced because the charging process of the capacitors is selectively controlled according to the digital control signal. From the experimental results, when dimming four LED lamps simultaneously, the average driving circuit efficiency of 89% is obtained, regardless of the dimming level. White light with color temperature over a range of 2800~7200K was produced by dimming control of red, green, blue and amber LED lamps with the proposed driving circuit. The characteristics of the driving circuits can be changed depending on the characteristics of the R, G, B, and A LED lamps. The efficiency of the driving circuits up to a maximum 89% can also be obtained depending on the combination of LED lamps. The driving technology with digital dimming control for LED lamps proposed in this paper would be effective for obtaining high efficiency in LED driving circuits and remote control of LED lamps using digital communications.