• Journal of IKEEE
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• v.22 no.2
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• pp.316-323
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• 2018

In this paper, we newly introduce the three-level byte-inversion transmission method for preventing LED flicker in visible light communication (VLC). The VLC transmitter sequentially sends the original signal and the inverted signal in byte units using a three-level LED modulator. The average optical power of the LED is kept constant during data transmission, thus flicker-free. In the VLC receiver, the original data is easily recovered using a simple comparator. This structure is very simple because additional clock or carrier is not required for flicker prevention. The developed flicker prevention scheme could be very useful for constructing the flicker-free indoor VLC system in low cost.

• Journal of information and communication convergence engineering
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• v.19 no.4
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• pp.269-275
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• 2021

Light-emitting diodes (LEDs) are modulated using a square wave pulse sequence for flicker prevention and dimming control in visible light communication (VLC). In a VLC transmitter, the high and low bits of the non-return-to-zero (NRZ) data are converted to two square waves of different frequencies, which continue for a finite time defined by the fill ratio in an NRZ bit time. As the average optical power was kept constant and independent of data transmission, the LED was flicker-free. Dimming control is carried out by changing the fill ratio of the square wave in the NRZ bit time. In the experiments, the illumination of the LED light was controlled in the range of approximately 19.2% to 96.2% of the continuous square wave modulated LED light. In the VLC receiver, a high-pass filter combined with a latch circuit was used to recover the transmitted signal while preventing noise interference from adjacent lighting lamps.

• Journal of Sensor Science and Technology
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• v.27 no.3
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• pp.143-149
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• 2018

In this paper, we introduce an edge-spike modulation method for visible light communication (VLC). This method is effective in preventing LED flicker and 120 Hz noise interference in base-band VLC. In the VLC transmitter, edge-spikes are generated by passing the digital data through a simple RC-high pass filter (HPF). The LED modulation of the edge-spikes does not change the average power of the LED light; thus it prevents LED flicker. In the VLC receiver, the 120 Hz noise from other lighting lamps is easily eliminated by RC-HPF, while the edge-spike signal is detected normally. In our experiment, the message of an air-quality sensor was successfully transmitted using edge-spike modulation. This structure is useful in constructing, e.g., wireless gas monitoring sensor systems to warn and prevent harmful gas leakage accidents in buildings using LED light.

• Journal of Sensor Science and Technology
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• v.29 no.3
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• pp.180-186
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• 2020

In this study, we applied edge-pulse modulation to prevent the flicker of light-emitting diode (LED) light in a visible light identification system. In the visible light transmitter, positive pulses were transmitted at the edges of the low-to-high transition points, and negative pulses were transmitted at the edges of the high-to-low transition points of the non-return-to-zero (NRZ) data waveforms. In the visible light receiver, the NRZ waveforms were regenerated by making low-to-high and high-to-low transitions at the point of the positive and negative pulses, respectively. This method has two advantages. First, it ensures that the LED light is flicker-free because the average optical power of the LED was kept constant during data transmission in the transmitter. Second, the 120 Hz optical noise from the adjacent lighting lamps was easily cut off using a simple RC-high pass filter in the receiver.

• Journal of Sensor Science and Technology
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• v.29 no.4
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• pp.243-248
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• 2020

In this study, we applied transition-frequency modulation to prevent the flickering of light-emitting diodes (LEDs) in visible light communication (VLC). In the VLC transmitter, rectangular waveforms with transition frequencies of four and two in each bit time were used for the high and low bits, respectively, in the non-return-to-zero data. In the VLC receiver, an RC-high-pass filter (HPF) was used to eliminate the interference of the 120 Hz noise light from the adjacent lighting lamps, and an SR-latch circuit was used to recover the transmitted signal using spikes from the output of the RC-HPF. This configuration is useful for constructing VLC systems that are flicker-free and resistant to adjacent noise light interference.

• Journal of Sensor Science and Technology
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• v.29 no.3
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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.

• Journal of IKEEE
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• v.23 no.2
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• pp.571-579
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• 2019

Visible light communication (VLC) performs illumination and communication simultaneously, thus it is important to prevent the flicker due to the optical power variation during data transmission and at the same time to have dimming control capability. In this paper, we used Manchester code for flicker-prevention and dimming control. In the transmitter, the duty factor of the Manchester code was used for controlling the LED illumination. In the receiver, the edge-spike signals of an RC-high pass filter were used for recovering the Manchester code while preventing the adjacent noise light. In experiments, the LED light was kept flicker-free and the average optical power was controlled in the range of 8~68 % of the continuous wave (CW) LED light by changing the duty factor of the Manchester code.

• Journal of IKEEE
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• v.24 no.2
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• pp.579-585
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• 2020

In this study, we used byte-inversion transmission method to prevent the flicker of lighting source in a visible light data communication link. In the transmitter, the non-return-to-zero (NRZ) signal with 9.6 kbps was on-off keying (OOK) modulated with a 100 kHz square wave carrier and byte-inversion signal was added after each byte to make the average optical power of the light-emitting diode (LED) constant. In the receiver, we used a band-pass filter to eliminate the interference of the 120 Hz noise which was induced from the adjacent light lamps, and an OOK demodulator to recover the original NRZ signal This scheme is useful in constructing wireless data networks using the illumination of visible light lamps.

• Journal of Convergence for Information Technology
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• v.8 no.3
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• pp.193-198
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• 2018

Recently, the casualties of automobile traffic accidents are rapidly increasing, and serious accidents involving serious injury and death are increasing more than those of ordinary people. More than 70% of major accidents occur in drowsy driving. Therefore, in this paper, we studied the drowsiness prevention system to prevent large-scale disasters of traffic accidents. In this paper, we propose a real-time flicker recognition method for drowsy driving detection system and drowsy recognition according to the increase of carbon dioxide. The drowsy driving detection system applied the existing image detection and the deep running, and the carbon dioxide detection was developed based on the IoT. The drowsy prevention system using both of these techniques improved the accuracy compared to the existing products.

• Journal of Trauma and Injury
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• v.35 no.2
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• pp.71-75
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• 2022

Trauma care is evolving throughout the world to meet the demand resulting from rapidly increasing rates of mortality and morbidity related to external injuries. The State Major Trauma Service was designated to Royal Perth Hospital in 2004 to provide comprehensive care for trauma patients in Western Australia (WA), which is the largest state by area in the country. The State Major Trauma Unit, which was established in 2008, functions as a level I center and admits over 1,000 major trauma patients per year, making it the second busiest trauma center in Australia. The importance of recording data related to trauma was identified by the trauma service in WA to inspire higher standards of patient care and injury prevention. In 1994, the service established a trauma registry, which has undergone significant changes over the last two decades. The current State Trauma Registry is linked to a statewide database called the Data Linkage System. The linked data are available for policy development, quality assurance, and research. This article discusses the evolution of the trauma service and the registry database in the WA health system. The State Trauma Registry has enormous potential to contribute to research and quality improvement studies along with its ability to link with other databases.