• Journal of Sensor Science and Technology
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• v.29 no.2
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• pp.75-81
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• 2020

We introduce a new visible light communication (VLC) method in which three-level return-to-zero (RZ) modulation is used for flicker-free transmission. In the VLC transmitter, the three-level RZ modulation ensures that the average optical power is constant; thus, a flicker-free light-emitting diode (LED) light is achieved. In the VLC receiver, a resistor-capacitor high-pass filter is used for generating spike signals, which are used for data recovery while eliminating the 120 Hz optical noise from adjacent lighting lamps. In transmission experiments, we applied this method for wireless transmission of an air quality sensor message using the visible light of an LED array. This configuration is useful for the construction of indoor wireless sensor networks for air pollution monitoring using LED lights.

• Journal of information and communication convergence engineering
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• v.18 no.3
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• pp.201-206
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• 2020

This paper presents a new method for controlling the current of lighting LEDs without current sensors. This method can be used as backup against LED current sensor faults. LED lighting requires a circuit with a constant current in order to maintain the same brightness when the ambient temperature changes. Therefore, we propose a new current estimation method to provide backup in case of current sensor faults based on the calculation of the inductor current. In the fabricated circuit, the average current changes from 144.03 mA to 155.97 mA when the ambient temperature changes from 0℃ to 60℃. The application of this study can enable the fabrication of a driving IC for LEDs in the form of a single chip without sensing resistors. This is expected to reduce the complexity of the peripheral circuit and enable precise feedback control.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.11
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• pp.755-762
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• 2014

In recent year, along with the rapid development of LED technology, many applications using LEDs with Visible Light Communication(VLC) have been researched. Since it is easy to provide LOS communication environment along with cheap deployment cost, the indoor positioning system based on VLC has been actively studied. In this paper, we propose an accurate indoor positioning algorithm using a stereo image sensor and white-light LEDs with the visible light communication. Indoor white-light LEDs are located at the ceiling of a room and broadcast their position information by VLC technology. Mobile receiver with stereo image sensor receives LED position information by VLC and estimates its position and angle information. Simulation results are given to show the efficiency of proposed indoor positioning algorithm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.602-604
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• 2016

In this paper, we propose that it can control the interior lighting, LED and alarm clocks based on Bluetooth. The proposed 'Bluetooth based LED Alarm Lamp'may be an ON / OFF by using a Bluetooth module, by the light sensor and voltage transformers were designed to adjust the ON / OFF and light intensity. Also 7-segment display the clock, it was used a piezo-buzzer that designed to ring an alarm in time. And to decrease the voltage by using the touch sensor can adjust the light brightness. It was also added the ability to align the alarm. This piece (Bluetooth based LED Alarm Lamp) can provide a comfortable environment inside the room of a resident if the environment is dark when voltage is maintained to be ON automatic system. And designed with emphasis being able to improve the quality of sleep due to weak light.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.6
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• pp.129-135
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• 2015

This paper shows significant methods that improve the lifespan of LED modules as well as efficiently using an aluminum heat-sink for LED module in high power. It proposes a method that raises stability and lifespan to protect LED modules and the power unit when the LED module has been used for a long hours at high temperatures. During the research, we applied a method of pulse-width modulation (PWM) in order to prevent the phenomenon that the entire power of a system is turned off and the lifespan is reduced when the LED nodule reacts to the high temperatures. To protect the LED module and SMPS based on high efficiency, a temperature sensor is attached underneath the circuit board and the sensor measures the temperature of circuit board when the LED module is powered on. The electrical power connected to SMPS is controlled by PWM when the temperature of the LED module reaches a particular temperature.

• 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.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.6
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• pp.1227-1232
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• 2017

In this study, we have studied a system to reduce the inconvenience and the accident rate at the intersection when the visually impaired use traffic information by using pressure sensor and ultrasonic sensor. By using the pressure sensor to light the strip LED, the driver recognizes the pedestrian, thereby reducing the accident rate. In addition to the pedestrian signal light information, the ultrasonic sensor and Bluetooth transmit the bus position information to the application so that the user can listen to the voice.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.4
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• pp.404-409
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• 2004

We fabricated photo-sensor for fluorescence detection in LOC. LOC is high throughput screening system. Our LOC screens biochemical reaction of protein using the immunoassay, and converts biochemical reaction into electrical signal using LIF(Laser Induced Fluorescence) detection method. Protein is labeled with rhodamine intercalating dye and finger PIN photodiode is used as photo-sensor We measured fluorescence emission of rhodamine dye and analyzed tendency of fluorescence detection, according to photo-sensor size, light intensity, and rhodamine concentration. Detection current was almost linearly proportional to two parameters, intensity and concentration, and was inversely proportional to photo-sensor size. Integrated LOC consists of optical-filter deposited photo-sensor and PDMS microchannel detected 50 (pg/${mu}ell$) rhodamine. For integrated LOC including light source, we used green LED as the light source and measured emitted fluorescence.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.508-510
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• 1995

A fiber-optic pressure sensor is fabricated with a photoelastic glass material. To remove the influence of external pertubation along the optical fiber, a new referencing technique is proposed by using two light sources. LED with 870nm wavelength is used as light source for reference signal, and LED with 660nm wavelength is used as light source for modulation signal. The fiber-optic pressure sensor system shows good linearity within the pressure range of 0 to 5 $kg/cm^2$.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.2
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• pp.102-108
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• 2011

The existing vessels lighting control system has several problems, which are complexity of construction and high cost of establishment and maintenance. In this paper, We designed low cost and high performance lighting control system at digital vessel environment. We proposed a system which recognize the user's emotions after obtaining the biological informations about user's bio information(pulse sensor, blood pressure sensor, blood sugar sensor etc) through wireless sensors controls the LED Lights. This system classified emotions using backpropagation algorithm. We chose 3,000 data sets to train the backpropagation algorithm. As a result, obtained about 88.7% accuracy. And the classified emotions find the most appropriate point in the method of controlling the waves or frequencies to the red, green, blue LED Lamp comparing with the 20-color-emotion models in the HP's 'The meaning of color' and control the brightness or contrast of the LED Lamp. In this method, the system saved about 20% of the electricity consumed.