• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 1998.09a
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• pp.68.1-68
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• 1998

• Molecular & Cellular Toxicology
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• v.3 no.sup4
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• pp.37.2-37.2
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• 2007

• ETRI Journal
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• v.44 no.1
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• pp.169-169
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• 2022

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.179-182
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• 2005

In this paper, optical noise is reduced using a differential detector in an 1.3$\mu$m optical wireless system which is more safe for human eye than 0.8$\mu$m optical wireless systems. The differential detector is composed of a InGaAs photodiode and a Si photodiode. This is a very simple and cost effective method to reduce the noise interference from incandescent lamps.

• Journal of Sensor Science and Technology
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• v.23 no.4
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• pp.238-244
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• 2014

In this paper, we introduce a new passive transponder that operates without external power in a visible light identification system. The transponder consists of a solar cell, a photodiode, a microprocessor, and a visible LED. When a reader sends light to the transponder, the solar cell generates current from the reader light and supplies power to the other elements in the transponder. At the same time, the photodiode detects the pulse in the reader light and initiates a microprocessor to generate and send a responding light to the reader. In experiments, we realized a passive transponder using a solar cell that operated at a distance of 1m without external power.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.357-362
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• 1993

In this study low priced laser measurement system was made, so its reliability was investigated Intensity distribution of laser beam measured by devised system and FFT analyzer and their results were examined for proving reliability of devised system. Transmitted laser beam intensity on photodiode changed by eccentrically rotating of disk cam and motor speed. To get results, photodiode and devised amplifier were used for changing voltage. After that, response signal was calculated by signal analysis program. It was found that the vibration of disk cam could be measured by the intensity distribution of laser beam and the same tendency was obtained by FFT. Change of motor speed effected the distribution of laser beam,which was obtained by devised system. Also linear distribution was got by sensitive balancing switch on amplifier according to the transmission of laser beam on photodide.

• Journal of electromagnetic engineering and science
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• v.16 no.4
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• pp.214-218
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• 2016

In this paper, we present an ambient light backscatter communication design that enables Internet of Things (IoT) devices to communicate through the backscattering ambient light emitted from lighting infrastructure or sunlight. The device can selectively modulate ambient light by switching a liquid crystal display (LCD) shutter located on its surface, so that a nearby smart device, which includes a photodiode or a camera, can demodulate this backscattered light information. To verify the practicality of the proposed concept, we design an IoT device equipped with a commercial LCD shutter and a microcontroller. Our device produces ambient light backscattered data at a speed of 100 bps, and these data are successfully decoded by a commercial photodiode module 10 cm away from the IoT device. We believe that our ambient light backscatter communication design is appropriate for implementation in various IoT applications.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1386-1392
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• 2009

An analysis is presented for super-high-speed optical demodulation by an avalanche photodiode(APD) with electric mixing. A normalized gain is defined to evaluate the performance of the optical mixing detection. Unlike previous work, we include the effect of the nonlinear variation of the APD capacitance with bias voltage as well as the effect of parasitic and amplifier input capacitance. As a results, the normalized gain is dependent on the signal frequency and the frequency difference between the signal and the local oscillator frequency. However, the current through the equivalent resistance of the APD is almost independent of signal frequency. The mixing output is mainly attributed to the nonlinearity of the multiplication factor. We show also that there is an optimal local oscillator voltage at which the normalized gain is maximized for a given avalanche photodiode.

• Journal of Korea Multimedia Society
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• v.19 no.11
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• pp.1862-1870
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• 2016

A respiration is one of the most useful techniques for vital checking and an abnormal respiration is often the earliest sign of critical illness. Detection of respiration is based on the photo-plethysmography (PPG) with photodiode technique. Because PPG sensor using photodiode can be easily miniaturized, it is suitable for wearable devices. A system to measure respiration rate based on PPG signal is implemented and for a reliable measurement an improved algorithm in accuracy using PPG signal pattern is proposed in this paper. As results regarding to three types of respirations (regular interval, free interval, and weak respiration) the proposed algorithm showed error rate of 0.047, 0.067, and 0.122 respectively.

• Journal of Internet Computing and Services
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• v.13 no.3
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• pp.17-22
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• 2012

In this paper, a photoelectric image detection system is proposed using an APD(Avalanche Photodiode) sensor, a LED illuminator, and fiberoptic waveguides. This proposed pinhole detection system can detect the pinholes of 100 micron with the speed rate of 1,000mpm(meter per minute). And detecting performance of image system is improved by the SQL based DB analysis of classifying pinhole's detected location and size using image detection algorithms.