• Transactions on Electrical and Electronic Materials
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• v.12 no.6
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• pp.253-257
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• 2011

This study was carried out to solve problems such as radio frequency band depletion, confusion risk, and security loss in existing visible wireless communication systems, and to determine the applicability of next-generation networks. A light-emitting diode (LED) light communication system was implemented with a controlling switching light module using the ATmega16 micro-controller. To solve the existing modulation effect and disturbance in visible light communication, an integrated interface was evaluated with a driving light module and analyzes its reception property. A transmitter/receiver using the ATmel's micro-controller, high-intensity white LED-6 modules, and infrared sensor KSM60WLM and visible sensor TSL250RD were designed. An experiment from the initial value of distance to 2.5 m showed 0.46 V of the voltage loss, and if in long distance, external light interference occurred and light intensity was lost by external impact and thus data had to be modified or reset repeatedly. Additionally, when we used 6 modules through the remote controller's lighting dimming, data could be transmitted up to 1.76 m without any errors during the day and up to 2.29 m at night with around 2~3% communication error. If a special optical filter can reduce as much external light as possible in the integrated interface, the LED for lighting communication systems may be applied in next generation networks.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1574_1575
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• 2009

This paper investigates the reduction of RE(Radiated Emission) noise in a high power LED module circuit using PWM(Pulse Width Module) switching controller circuit. Poorly designed LED lighting module can experience the RE and CE(Conducted Emission) noise problem. This paper propose the reduction of noise source and improvement of EMI filter design in a high power LED lighting module. The experimental and simulation results showed that reduce the RE noise level effectively.

• Journal of the Korea Computer Industry Society
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• v.6 no.5
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• pp.741-748
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• 2005

Power saving module which is consisted of ferroelectric ceramic capacitor and time delay switching circuit was installed into electronic ballast in order to enhance energy efficacy and extend life time of fluorescent lamp. The impedance matching of negative resistance characteristics of F/L was optimized with the characteristics of ferroelectric ceramics capacitor to increase the light efficiency of the electronic ballast. The high efficiency of the electronic ballast was achieved by minimizing wasted power at the filament of F/L during the lighting by using the switching function of time delay circuit from preheating mode to non-preheating mode. The life time of F/L was also extended by eliminating the reverse electromotive force using time delay circuits to minimize the impacts to the filament of F/L from unwanted high voltage peaks during light-up period. As the results, the electronic ballast with the first grade energy efficiency was developed using ferroelectric ceramics and time delay module.

• Journal of electromagnetic engineering and science
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• v.16 no.4
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• pp.214-218
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• 2016

In this paper, we present an ambient light backscatter communication design that enables Internet of Things (IoT) devices to communicate through the backscattering ambient light emitted from lighting infrastructure or sunlight. The device can selectively modulate ambient light by switching a liquid crystal display (LCD) shutter located on its surface, so that a nearby smart device, which includes a photodiode or a camera, can demodulate this backscattered light information. To verify the practicality of the proposed concept, we design an IoT device equipped with a commercial LCD shutter and a microcontroller. Our device produces ambient light backscattered data at a speed of 100 bps, and these data are successfully decoded by a commercial photodiode module 10 cm away from the IoT device. We believe that our ambient light backscatter communication design is appropriate for implementation in various IoT applications.