• Journal of Advanced Marine Engineering and Technology
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• v.38 no.2
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• pp.169-174
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• 2014

This paper proposes a novel beehive-shaped reflector for application to light-emitting diode (LED) transceivers for illumination and bi-directional visible light communication (VLC). By using a diffuse propagation model extended to line-of-sight and direct signals, the distribution of illuminance and the path loss of the transceiver are investigated to evaluate the performance of the beehive-shaped reflector. To verify bi-directional communication, a VLC-based image capture system, comprising a complementary metal-oxide semiconductor (CMOS) image sensor and video processor unit, is demonstrated. Real-time images captured by the CMOS camera are successfully transmitted to the monitoring system via a free-space channel at a rate of 115.2 kbps.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.237-241
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• 2005

We present a device model for organic light emitting diodes(OLEDs) which includes charge injection, transport, recombination, and space charge effects in the organic materials. The model can describe both injection limited and space charge limited current flow and the transition between them. Calculated device current, light output, and quantum and power efficiency are presented for different cases of material and device parameters and demonstrate the improvements in device performance in bilayer devices. These results are interpreted using the calculated spatial variation of the electric field, charge density and recombination rate density in the device. We find that efficient OLEDs are possible for a proper choice of organic materials and contact parameters.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.2
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• pp.221-227
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• 2021

Recently, interests in mask-type skin care devices using light-emitting diodes have been increasing and optical stimuli at certain wavelengths have been known to have various therapeutic effects, such as skin whitening, acne treatment, elasticity and wrinkle improvement by controlling the exposure to wavelengths of light and irradiation time. In particular, light sources of different wavelengths are applied in masks for the purpose of suppressing skin aging, inducing cell proliferation, and alleviating skin inflammation. In this paper, we developed a light-emitting diode control system that is actively used in skin regeneration masks using a microcontroller. Optical stimuli with different manners were applied to skin fibroblast cells in a single or complex wavelengths, and then confirmed how they are effective in the cell differentiation. In addition, we found a specific wavelength that has a positive effect on cell proliferation rates, and confirm the effectiveness of cell proliferation by image processing based quantitative analysis.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.65-67
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• 2021

This thesis is to proposer a new algorithm for a position measurement system using a trilateration method through visible light communication(VLC), by light emitting diode(LED). The length from each LED to the sensor is derived, and location information is found using trilateration method based on the derived length. Unlike th existing positioning system using visible light communication, the proposed positioning system is simpler and more cost effective because it does not require communication between the transmitter and the receiver.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.1
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• pp.51-56
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• 2013

In this paper, we had design the module of the LED-based media transmission mechanics visible light communication system. To implement the media transmission system through visible light communication transmitter, receiver module the using high brightness, we proposed visible light communication system to implement communication distance of up to a maximum transmitter-receiver distance using a variable PD sensor to the receiver and 1~12 the LED light-emitting device to the transmitter. It was increased efficiency of approximately 20% by measuring the performance during lens wearing or not wearing on the LED module to improve the efficiency of the media transmission system.

• Journal of Industrial Technology
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• v.30 no.B
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• pp.113-118
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• 2010

In this paper, We proposed remote dimming control system for Light Emitting Diode(LED) street light using Power Line Communication(PLC). LED will be used widly by indoor or outdoor lighting because of semi-permanent life and environment restriction. For energy saving of street light, the dimming control system is very necessary and the PLC is a very efficient technique. Thus, in this paper we proposed the remote dimming control system for LED street light using PLC. A performance of the proposed system was validated by experimental results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.4
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• pp.740-749
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• 2015

In the visible light (VL) communication based on the conventional LED lights, depending on the increase of the communication range, the signal received at the photodiode of the VL receiver has usually the random distorted and decreased amplitude due to the path loss and fading effects of the VL channel. In order to overcome this problem, we propose, design, and implement the visible light communication circuit based on the comparator threshold voltage, where has a built-in distance compensation function. In addition, the performance of the proposed technique is evaluated and analyzed depending on the distance and communication speed through comparing the proposed VLC system based on the threshold voltage with the conventional one.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.9B
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• pp.1117-1125
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• 2011

In this paper, as a study of the simple visible light communication(VLC) with LED light, the visible light communication system that are made up with the $3{\times}3$ white LED array for visible light transmission, various photodiodes for visible light reception, and a non-carrier NRZ-OOK modulation scheme is designed and implemented to have a 115.2 kbps data speed at 2.5 m distance between transmitter and receiver. For the performance analysis of the developed VLC system, the maximum distance between VLC transmitter and receiver on the conditions of various transmission speeds, the number of LED array, or the various kind of LED and photodiode is obtained, and various performances are analyzed by experiments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.8
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• pp.1653-1662
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• 2012

Recently, Organic Light Emitting Diode (OLED) that is broadly applied as next generation display has various advantages. However, OLED display causes unbalanced color tone due to the difference of luminance efficiency among luminous elements. In this paper, we propose adaptive color shifter (ACS) to resolve the RGB channel unbalance and to have wide color range of a relatively weak channel using the image processing method. proposed ACS system was simulated using a variety of image. Also, we numerically analyzed using hue histogram, CIE-1931 xyz color space.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.139-140
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• 2010

This paper presents an indoor prototype for wireless digital signal transmission using Visible Light Communications (VLC) in which high power Light Emitting Diode (LED) is used. Using low cost and off-the-shelf components, the transmitter module is constructed using an AVR Atmega128 microcontroller and commercial white beam LEDs. Modulating the light intensity of the LED enables digital signals to be transmitted across the optical link. The receiver module employs a high speed PIN photodetector for optical signal detection and a recovery circuit for optical-electro signal conversion. By sending digitalized data via VLC technology, many applications can be realized in the areas of consumer advertising, traffic safety information and disaster control.