• Journal of Sensor Science and Technology
• /
• v.23 no.5
• /
• pp.349-355
• /
• 2014

In this paper, we developed a new method to transmit multiple visible light channels in time division mode using the AC power line frequency in order to prevent the crosstalk between adjacent optical signals. Synchronizing pulses are generated from the 220 V power line, and one pulse period is subdivided into several time slots for visible light channels. Each channel transmits data in a predefined time slot without interfering adjacent channels. In experiments, synchronizing pulses with a repetition rate of 240 Hz were generated from the 60 Hz power line, and three VLC channels with a bit rate of 9.6 kbps transmitted data independently using the time slots between synchronizing pulses. This configuration is very useful in constructing time division VLC networks for multiple sensors.

• Journal of Broadcast Engineering
• /
• v.14 no.1
• /
• pp.70-80
• /
• 2009

We propose an ideal line coding for high speed data communication in visible light communication system. B4-HBT line coding is defined as follow. The 1 bit is +V at first though 1 encodes +Voltage and -Voltage doing change of shift each other, then -V newly. V that is been mutually contradictory for 1 bit that exist before that if continuous 0 bits exist 4 here same and reduces mistake because has reverse mark V in 4 continuous last 0 bits and gives half bit variation in 1 bit and made effect of noise low. 2${\sim}$3 dB profit is seen comparing with line coding that exist in simulation result.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2017.05a
• /
• pp.738-740
• /
• 2017

Visible light communication is a communication method using light, and it has advantage of ensuring security in a single space as compared with RF communication. However, in the area outside the visible line of the light, communication disconnection occurs. Therefore, this paper proposes a relay module to overcome the coverage extension and communication disconnection phenomenon of visible light communication. The proposed relay module transmits and receives data of visible light communication by sequentially transmitting data packets including target ID through adjacent visible light module. Through experimentation of data transmission, we confirmed the extension of the transmission range and the data reception in the area outside the line of sight.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.27 no.4
• /
• pp.73-79
• /
• 1999

This study is on the production and the classification of a new appreciation methods of seascape through materials in the words of Korean popular songs. In advance, it is necessary to understand the popular songs as collective representation and the songs are analytic data. In this study, some essential elements of seascape in popular songs are analyzed and classified. They are; 1. visible elements-weather, time, season and object. 2. all senses-vision, audition, olfaction, tactile sense, and spatial sense. 3. the line of vision-static line of vision and dynamic line of vision. In this way data is produced, and then the result of this study makes appreciation methods of seascape developed. In this way, this study results in developed appreciation of seascape. This study on new understanding of appreciation methods of seascape is on the basis of a design method of water-front that is considered a visible scene, not a design of construction elements.

• Transactions on Electrical and Electronic Materials
• /
• v.11 no.5
• /
• pp.238-241
• /
• 2010

The purpose of this study is to solve the problems of radio frequency bandwidth frequency depletion, confusion possibilities, and security that are in current wireless communications systems, and to confirm the possibility of applying those solutions for the next generation network. To solve the problems of the current wireless communications system, a visible light communications system for power line communication (PLC) via 8-bit microcontroller is created and the capacity is analyzed. The exclusive PLC chip APLC-485MA, an 8-bit ATmega16 microcontroller, high brightness 5pi light emitting diodes (LEDs), and the LLS08-A1 visible light-receiving sensor were used for the transmitter and receiver. The performance was analyzed using a designed program and an oscilloscope. The voltage change was measured as a function of distance from 10-50 cm. Blue LEDs showed the best performance among the measured LED types, with 0.47 V of voltage loss, but for a distance over 50 cm, precise data was not easy to obtain due to the weak light. To overcome these types of problems, specific values such as the changing conditions and efficiency value relevant to the light emitting parts and the visible light-receiving sensor should be calculated, and continuous study and improvements should also be realized for better communication conditions.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.11
• /
• pp.2043-2047
• /
• 2010

This study is to solve problems of depletion of RF bandwidth frequency, confusion possibility, security that current wireless communications system have and is to confirm possibility of applying next generation network. To solve problems of current wireless communications system, visible light communications system for power line communications using ATmega16 Microcontroller is was realized and receiver property was analyzed. PLC exclusive chip APLC-485MA, Microcontroller ATmega16, 5pi bulb type LED and high flux LED, visible light receiving sensor LLS08-A1 were used for transmitter and receiver. Performance was analyzed by designed program and an oscilloscope. It was showed average 20% improved receiver rate rather than bulb type LED in the case of high flux LED through voltage change rate on communication distance and LED type of distance between 10 to 50 cm. The blue LED showed the best performance among measured LED types with above 10% of voltage decreasing rate. But As it gradually becomes more distant, the precise date was difficult to obtain due to weak light. To overcome these sort of problems, specific values such as changing conditions and efficiency value relevant to light emitting parts and visible light receiving sensor should be calculated and continuous study and improvements should also be accomplished for the better communications condition.

• Journal of Satellite, Information and Communications
• /
• v.7 no.3
• /
• pp.41-46
• /
• 2012

Visible light communication(VLC) system based on LED devices has some specific advantages compared with RF system. First, visible light is harmless to human and there is no limit to using frequency band. Also, VLC system has good security performance, and it can use the very wide frequency band for data transmission. However, for simultaneously using the illumination and data transmission in VLC systems, degradation of code rate is occurred. So, in this paper, we proposed the novel line coding scheme for flicker free and efficient dimming control in VLC systems. From the simulation results, it is confirmed that proposed scheme has good flicker, dimming, and transmission performance compared to conventional variable pulse position modulation(VPPM) scheme.

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

• Journal of Sensor Science and Technology
• /
• v.22 no.3
• /
• pp.212-218
• /
• 2013

In this paper, we introduce a new method to reduce the inter-channel crosstalk in visible light communication (VLC) systems using the synchronizing pulses transmitted through the power lines. Synchronizing pulses are simultaneously transmitted to multiple VLC transmitters and receivers through the 220V power line. Each VLC transmitter modulates an LED and each VLC receiver demodulates the signal light in the time slot that is allocated with reference to the synchronizing pulses. This method is very simple and effective to prevent the inter-channel crosstalk in VLC systems for sensor networks because every VLC system can easily get the synchronizing pulses from the nearby power line.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.1147-1148
• /
• 2015

This study demonstrates the coating effect of carbon nanotubes on metal meshes, which have been made with various line-spaces and line-width, for touch screen panels. The CNTs have been deposited on metal meshes via electrophoretic deposition (EPD). The sheet resistances, visible transmittances, visible reflectances have been measured before and after electrophoretic deposition. The experimental results confirm that CNT coating metal meshes with various line-spaces and line width can satisfy the requirements that are required for transparent electrodes of touch screen panels.