• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.6
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• pp.281-285
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• 2010

We propose new identification method of LED location in indoor environment. It can transmit and receive position information and additional data, as applying OOK-SS watermarking method for LED transmission signal. Especially, we use a unipolar form code for watermarking spread code, because LED signal has unipolar characteristic. we analysis LED signal influence and interference with watermarking code, demonstrate usefulness of LED-ID using OOK-SS Watermarking.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.10B
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• pp.1246-1251
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• 2011

In this paper, BPSK-OFDM-based LED communication systems are applied to watermarking techniques, were studied on how to transfer the additional information data with at the same time as the transfer of LED communication data. For watermarking kasami code was used as spreading codes, and spread additional data is controlled by small signal level to be BPSK-OFDM does not affect the optical signal. BPSK-OFDM is added to an optical signal is transmitted. The performance of the spreading code as a kasami code is autocorrelation of the noise-free environment, under the noise environment was confirmed by autocorrelation. BPSK-OFDM-based LED communication system has been applied proposed technique throughout the simulation in analyzed to BER of BPSK-OFDM DER performance and watermark signal level according to signal size level of data. That was availability confirmed for watermarking data transmit techniques data as being analysis detection performance of watermarking information using LED communication according to the code.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.3A
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• pp.189-197
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• 2011

OFDM systems are much studied for the recent high speed wireless optical communication system. OFDM system has basically high PAPR and ICI easily generated because of non-linearity and RF impairments. In the wireless optical communication system, optical output power driven by current of LED is not linear so that transmission signals are distorted. Therefore, research about reception performance of this nonlinear optical output emitted by non-linear LED transfer function and OFDM signal has been conducted. Nonlinear effect of LED is different from nonlinear effect of OFDM system in the conventional radio communication system, which degrades the BER performance. In this paper, we apply non-linear transfer function of recently studied LED into OFDM system. So, for reducing the PAPR and suppressing the ICI in frequency domain of receiver, we suggest a new PAPR reduction technique to reduce non-linear distortion of LED and an adaptive ICI suppression algorithm so that BER performance may be improved. Also, the proposed method is verified through simulation results.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2017.11a
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• pp.92-93
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• 2017

최근 IT 및 사이니지 기술을 포함한 여러 기술의 발전 형태가 융복합적 기술의 방향으로 전환됨으로서, 기술 간 장벽이 허물어지고, 상호 연관성을 갖게 됨에 따라 사이니지 및 IT기술이 접목된 새로운 융복합 기술에 대한 연구가 지속적으로 이루어지고 있다. 특히, LED 광원의 일종인 사이니지를 이용하여 광 데이터를 전송할 수 있는 기술에 대한 연구가 학계, 연구소 및 관련 산업체 등에서 지속적으로 진행되고 있는 상황이다. 이에 본 논문에서는 LED 전광판 사이니지를 이용하여 무선광통신이 용이한 LED 소재에 대한 연구를 진행하였다. LED 전광판 사이니지를 이용한 무선광통신 기술은 LED 광원이 지닌 특성을 토대로 RF방식 대비 높은 주파수 대역과 고속의 데이터 전송이 가능하기 때문에 높은 잠재력과 파급력을 통하여 무선통신 분야에서의 새로운 통신 척도로 활용될 수 있을 것으로 예상된다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.6A
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• pp.587-591
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• 2011

In a visible light communication (VLC) system using LEDs, its nonlinearity degrades the performance. If it is compensated by using predistortion and LED's linear range is extended, then a large signal can be used as an LED input and the performance of VLC will be improved. In this paper, a predistortion curve is made by periodic measurement of LED nonlinearity, and the experimental results of predistorted OFDM is provided.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.66-72
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• 2016

An LED lighting control system was developed to combine information technology and LED lights for efficient management and energy savings. The system can monitor and control the status of an LED luminaire using Bluetooth wireless communication, sensor technology, and smart phones. An LED lighting control circuit was designed using a temperature sensor, illumination sensor, and Bluetooth module with a fuzzy constant-current control circuit. We extended the lifetime and prevented damage to the LED by optimizing the supply current of the LED luminaire based on the heat-generation temperature of $70^{\circ}C$ of an LED heat sink. We also automatically adjusted the ON/OFF time depending on the ambient illumination of the LED luminaire. By allowing easy control of the LED luminaires on a smartphone, we improved the efficiency and achieved energy savings. The control system was validated through experiments for normal operation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.440-443
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• 2011

This paper aims to compose a new LED lighting control board in the LED lighting environment This LED lighting control board is designed to adjust the brightness of LED lighting depending on the change of surrounding brightness, and it is also designed to control the brightness by using ATmega128, which is an 8bit micro-controller, The PWM wave form likely to output into the LED driver is determined by the ADC value input through ADC.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.1
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• pp.66-74
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• 2013

This paper introduces the improvement of QoS to compensate the decreasing LED performance by temperature characteristic in the LED-ID communication system. LED does not only use as a lighting device, but also uses as a communication device. The conventional system is transmitted by RGB of LED following the mixture color ratio, which determined the color of lighting, and the BER performance of each RGB signals. However, when the LED used consistently, it has occurred the heat temperature. As a result, LED is degraded the performance by increased temperature each device. To solve this problem, we proposed the adaptive modulation and coding scheme by temperature of device to improve the performance of system and satisfied the QoS in the LED-ID system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.534-535
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• 2013

최근 LED 기술을 활용한 LED 조명은 밝기와 수명 및 저전력이라는 장점으로 인하여 현재 시중에 급속도로 퍼저 나가고 있다. 이러한 LED를 조명으로 사용하기 위한 기반 기술은 SMPS(Switching Mode Power Supply) 설계 기술이라 할 수 있다. 또한 LED 성능은 입력 전원 상태 및 LED 조명의 부하 조건에 따라 오차가 발생하여 LED등의 균일한 밝기를 유지하는데 기술적으로 많은 어려움이 있다. 본 논문에서는 12[W] 급 LED 다운 라이트에 대하여 LED SMPS의 전류 출력에 대하여 정전류제어를 함으로서 입/출력 조건의 변동에 대응하여 보다 안정적인 LED 등의 균일한 밝기를 유지하기 위한 12[W] 급 LED 다운 라이트용 SMPS에 PFC(Power Factor Correction) 회로를 추가하여 역율을 개선을 하며, 전압 위상에 따른 전류 위상 분포를 규일 비율로 제어 하여 보다 안정적인 밝기를 제공하는 12[W] 급 LED 조명용 SMPS를 개발하여 상품화를 제안하고자 한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.971-974
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• 2014

Reflect the social concerns of recent energy saving in this paper. The LED market is continuing to grow continuously. But it is now high light energy conversion led lights., We propose converting the light energy-saving method for these LED lights. Generated the cumulative loss of the conversion done at each light change from the current power of the LED lights. The cumulative loss to achieve minimal energy loss resulting from the improved performance.