• 센서학회지
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• 제29권3호
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• pp.149-155
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• 2020

In this study, we employed Manchester code for illumination control and flicker prevention of the light-emitting diode (LED) used in a visible light communication (VLC) system. In the VLC transmitter, the duty factor of the Manchester code was utilized for illumination control; in the VLC receiver, the spike signal from an RC-high pass filter was utilized to recover the transmitted signal whilst suppressing the 120-Hz noise arising from adjacent lighting lamps. Instead of the clock being transmitted in a separate channel, a syncmark signal was transmitted in front of each data byte and used as the reference time for transforming the Manchester code to non-return-to-zero (NRZ) data in the receiver. In experiments, the LED illumination was controlled in the range of approximately 12-84% of the constant wave (CW) light via changing of the duty factor from 10% to 90%. This scheme is useful for constructing indoor wireless sensor networks using LED light that is flicker-free and presents capability for illumination control.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2008년도 정보통신설비 학술대회
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• pp.273-276
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• 2008

This article describes a LED illumination infrastructure for ubiquitous society based on the Visible Light Communication technology. The VLC is one of the advanced communication system using "Visible Light". The VLC system has a lot of advantageous features and can be used in various places for the next future generation. So, we analyzed ubiquitous service model based on the VLC system and some applications. And we renewed discussion about LED illumination infrastructure for u-Society.

• 조명전기설비학회논문지
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• 제26권9호
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• pp.1-7
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• 2012

In this paper, we present a new lighting control method considering ambient light in addition to the required lighting illumination for efficient energy saving of a LED stand. We estimate accurate environmental illuminance using a cheap illuminance sensor by modeling measured- and actual-illuminance using quadratic polynomial approximation. The relation between PWM(Pulse Width Modulation) duty ratio and illuminance intensity is modeled by a linear model. Illumination of the LED stand is controlled by estimating the difference of required illumination and the estimated ambient illumination. The developed LED stand has reduced electric energy consumption compared with a conventional manually controlled LED stand with the same lighting source. In addition, human subject evaluation shows that the LED stand, which is applied the proposed method, is more satisfactory than conventional ones since the proposed automatic controlled illumination produce more accurately required lighting and it is convenient.

• 한국정보통신학회논문지
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• 제21권2호
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• pp.367-372
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• 2017

LED 조명은 IT융합 시대로의 진화에 따라 단순조명에서 인간중심화 및 다기능화 시스템 조명으로 발전하였다. 이로 인하여, 다양한 센서기능, 통신기능 등의 IT기술과 응용소프트웨어와의 융합을 통하여 사용 환경 변화에 따른 조명 제어로 에너지가 절감되고 빛의 세기와 색 조절 등 다양한 사용자 중심의 맞춤형 조명이 요구 되고 있다. 이러한 지능화된 시스템 조명을 위해서는 사용자 중심의 센서 적용 및 제어가 가능해야한다. 따라서 본 논문에서는 LED 조명관제를 위한 유무선 통신 플랫폼 및 관제시스템을 제안하고자 한다. LED 조명 관제 시스템은 Bluetooth 매쉬 네트워크를 통해 데이터를 송수신하며, LED 조명 제어, LED 조명 상태 모니터링, 에너지 사용량 모니터링, 에너지 피크점 관리 등의 기능을 제공한다. 제안한 유무선 통신 플렛폼과 관제시스템을 통해 LED 조명의 수명 연장 및 에너지 절약 등이 가능할 것으로 기대된다.

• 한국전자통신학회논문지
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• 제9권4호
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• pp.499-508
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• 2014

본 논문에서는 생체신호인 PPG, GSR 신호의 변화에 따라 구동되는 LED 감성조명 시스템을 구현하였다. 개발된 GSR 및 PPG 센서모듈로부터 인체의 생체신호를 측정하고, 측정된 생체신호를 이용하여 MCU에서 제안된 각성 이완 판별맵에 근거하여 피검자의 각성 또는 이완 상태를 판단한다. 피검자의 상태에 대응하는 LED 조명색상의 변화를 주어, 피검자가 안정 상태의 감정에 도달할 수 있도록 하는 감성조명 시스템을 개발하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.36-39
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• 1997

In this paper, we described an approach to design of precision optical system for visual inspection of solder joint defects of SMC(surface mount components) on PCBs(Printed Circuit Board). The illumination system, consisting of three tiered LED lamps and one main camera and four side view camera, is implemented to generated iso-contour on the solder joint according to gradient of the soldered surface. We analyze LED design parameter such as incident angle, diameter of LED ring, and so on to acquire uniform illumination.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 춘계학술대회
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• pp.560-562
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• 2010

오늘날 LED 조명 시스템은 전력을 적게 소비하고 형광등보다 긴 수명을 가진다. 가시광 통신은 LED 가시광(RGB)을 이용한 무선 통신이다. 본 논문에서는 LED 조명을 이용하여 위치 기반의 실내 내비게이션을 구현하고 지하주차장에서 가시광 통신을 이용하여 주차 가능한 대수와 위치 등의 정보를 안내해 주는 주차안내 시스템을 설계하였다. 우리는 모의실험을 통하여 가시광 무선통신을 이용한 지하주차장에서 주차안내 시스템의 가능성을 알아보았다.

• Journal of Biosystems Engineering
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• 제37권5호
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• pp.314-318
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• 2012

Purpose: This study was conducted to develop a measurement system for determining photosynthetic photon flux (PPF) distribution and illumination efficiency of LED lamps. Methods: The system was composed of a linear moving sensor part (LMSP), a rotating part to turn the LMSP, a body assembly to support the rotating part, and a motor controller. The average PPF of the LED lamp with natural cooling and water cooling was evaluated using the measurement system. Results: The PPF of LED lamp with water cooling was 3.1-31.7% greater than that with natural cooling. Based on the measured value, PPF on the horizontal surface was predicted. Illumination efficiency of the LED lamp was slightly increased with water cooling by 3.4%, compared with natural cooling. A simulation program using MATLAB was developed to analyze the effects of the vertical distance from lighting sources to growing bed, lamp spacing, and number of LED lamps, on the PPF distribution on the horizontal surface. The uniformity of the PPF distribution of the LED lamps was fairly improved with 15 cm spacing, as compared to the 5 cm spacing. By simulation, PPF of $217.0{\pm}27.9{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ was obtained at the vertical distance of 40 cm from six LED lamps with 12 cm spacing. This simulated PPF was compared to the measured one of $225.9{\pm}25.6{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$. After continuous lighting of 346 days, the relative PPF of LED lamps with water cooling and natural cooling was decreased by 6.6% and 22.8%, respectively. Conclusions: From these results, it was concluded that the measurement system developed in this study was useful for determining PPF and illumination efficiency of artificial lighting sources including LED lamp.

• 한국자원식물학회지
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• 제25권6호
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• pp.731-738
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• 2012

Dandelion has been widely utilized for medicinal and edible purposes. This research was conducted to evaluate the effect of supplemental LED (light-emitting diode) light on germination, growth characteristics and anthocyanin content of dandelion (Taraxacum officinale) seedling using LED blue (460 nm), red (660 nm, R), blue + red (B:R=6:4) and fluorescent lamp light treatment. By LED illumination to T. officinale seed germination speed was delayed, and germination rate was the highest in the fluorescent light. The growth characteristics (plant height, number of leaves, root length and fresh weight) were greatly influenced by supplemental LED light compared with control treatment, and the growth promotion was the most effective in the red LED illumination. After 60 days of red and mixed LED light treatments, anthocyanin content of dandelion plants was significantly changed. The anthocyanin content was increased by 12~19 mg/100 g under the red LED and the mixed light conditions compared with the control and the blue LED. Results indicate that illumination with red and mix LEDs, compared with other light treatments, is beneficial for promotion of growth and anthocyanin content in dandelion.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.67-68
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• 2007

The introduction of high brightness LEDs with white light and monochromatic colors have led to a movement towards specialty and general illumination applications. Because drive circuit of illumination LED has an effect on efficiency and life, research about the drive circuit following LED characteristic is needed. This paper proposed a implementation of the stand-alone LED lighting system using battery from photovoltaic power generation.