• Current Optics and Photonics
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• v.4 no.3
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• pp.186-192
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• 2020

This paper describes a real-time monitoring system in Ethernet passive optical networks (EPON) that uses burst-mode fiber Bragg grating (FBG) optical sensors. The FBG interrogation unit in the optical line terminal (OLT) transmits the monitoring wavelength to optical network units (ONUs). The FBG sensor unit in each ONU returns a burst-mode monitoring signal to the OLT. As the system applies time division multiple access (TDMA), a uniform Bragg wavelength can be used to monitor the EPON system. The FBG interrogation unit analyzes the received burst-mode monitoring signals and outputs fault information on the ONU branches in EPON. The simulation results show the effectiveness of the proposed monitoring system based on TDMA. In addition, we compared the proposed TDMA-based monitoring system with a WDMA-based monitoring system.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2461-2466
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• 2003

This paper presents a simple sensor fusion algorithm using neural network for navigation of mobile robots with obstacle avoidance and trap recovery. The multiple sensors input sensor data to the input layer of neural network activating the input nodes. The multiple sensors used include optical encoders, ultrasonic sensors, infrared sensors, a magnetic compass sensor, and GPS sensors. The proposed sensor fusion algorithm is combined with the VFH(Vector Field Histogram) algorithm for obstacle avoidance and AGPM(Adaptive Goal Perturbation Method) which sets adaptive virtual goals to escape trap situations. The experiment results show that the proposed low-level fusion algorithm is effective for real-time navigation of mobile robot.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.97.5-97
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• 2002

A sensor modeling via artificial neural network is presented in this paper. The optical sensor has been designed to treasure absolute 3-dimensional positions and orientations of objects in 6-DOF. The method utilizes a triangular pyramidal mirror having an equilateral cross-sectional shape referred as 3-facet mirror. The mirror has three lateral reflective surfaces inclined 45 degrees to its bottom surface. The 3-facet mirror is mounted on the object whose 6-DOF motion is to be measured. As optical components, a He-Ne laser source and three position-sensitive detectors(PSD) are used. The laser beam is emitted from the He-Ne laser source located at the upright position and vertically incident o...

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.5
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• pp.145-150
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• 2007

Optical communication according to request of technology of communications and optical fiber to be full filed faster communication and pass over transmission capacity limit per unit area, per unit hour appeared, and this optical fiber acts the biggest role to influence performance of optical communication network. Optical fiber(PMF Polarization Maintaining Fiber) is used, and is used by electric field measurement, self-discipline measurement, sensor(Sensor) Department by high definition measure such as thermometry and storehouse component that use because make broad sense status and polarized light information in passageway and union with storehouse integrated circuit etc. that use broad sense interference developing could transmit in state that keep transmitting broad sense plane of polarization is polarized light existence. Also, research is developed by optical fiber for Coherent communication recently.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.2
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• pp.81-86
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• 2013

In this paper, the parameter identification for localization scheme for the optics-based micro sensor node is conducted. We analyzed short measurement range problem which can be occurred in optical based micro sensor node localization method using a time of flight. And we set up the theory for distance and maximum reflected laser power to overcome the problem by identifying hardware parameters like laser power, effective area of MEMS CCR, sensitivity of photodetector, and so on. Experimental results of measurement of maximum reflected laser power were compared with results of the theory. By using the theory, we can identify hardware parameters of localization scheme to measure particular position of the optics-based micro sensor node.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.215-220
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• 2005

In order to apply to land mine detection effectively, GPR using an optical electric field sensor as a receiver has been developed. The optical electric field sensor is very small and uses optical fiber instead of metallic coaxial cable. With the combination of these advantages and the bistatic radar system, it can be possible for an operator to measure quite flexible and safely. The sensor has been tested in stepped frequency radar system with frequency which consists of a vector network analyzer, a fixed double ridged horn antenna as transmitter. For considering effectiveness in real field, we applied impulse radar system, which consist of a digital oscilloscope and a impulse generator to produce the impulse. Detection of a PMN2 mine model was carried out by the impulse radar system at a sand pit. The PMN2 were detected clearly with sufficiently high resolution, the target contrast was almost the same while the scanning time decreased down to 1/100.

• Journal of Sensor Science and Technology
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• v.7 no.1
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• pp.23-30
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• 1998

In this paper, we analyzed the effect of the time delay of the image sensor in the tracking loop of Electro-Optical Tracking System(EOTS). we showed that Smith predictor can greatly improve the stability and various performances of EOTS with time delay. And also, to verify the realistic validity, we executed the experiment in EOTS recently developed, and confirmed the effectiveness in EOTS.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.10B
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• pp.1216-1221
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• 2011

We propose a multiplexed fiber Bragg grating (FBG) sensor network for vessel monitoring to measure the variation of strain and temperature by environmental perturbation based on code division multiple access (CDMA). The center wavelength of FBG was linearly changed by environmental perturbation such as strain and temperature variation so that we could be monitoring the state of sensors. A RSOA was used as optical broadband source and which was modulated by using pseudo random binary sequence (PRBS) signal. The correlation peak of reflected signal from sensor networks was measured. In this paper, we used the sliding correlation techniques for high speed response and dynamic rage of sensors.

• The KIPS Transactions:PartD
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• v.15D no.2
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• pp.263-270
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• 2008

Research of ubiquitous computing becomes more popular topic along with the rapid development of wireless technologies. Firstly, research and development on RFID focuses on manufacturing and retail sectors, because it can improve supply chain efficiency. But, it changes to USN (Ubiquitous Sensor Network) by adding a sensor and wireless network technologies on it. In this research, we design and implement the electric facility management service framework to collect real time information of electric facility using RFID/USN. In electric power industry, it is important the supply of energy must be guaranteed. So many power utilities control and supervise the transmission line to avoid power failures. Utilities install many types of sensor to monitor important facilities by wired network such as optical cable and PLC. In this research, we develop the sensor node which is small, easy to install and using wired network. We design the service framework for electric facility management to collect data using RFID tag, reader and wireless sensor nodes and implement the electric facility management service.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.4
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• pp.495-501
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• 2014

Piezoresistive-type, capacitive-type, and optical-type sensors have mainly been used for measuring a strain. However, in building a sensor network for remote monitoring using these conventional sensors there are disadvantages such as the complexity of a measuring system including wireless communication circuitry and high cost. In this paper, we demonstrates a highly-sensitive surface acoustic wave (SAW) strain sensor which is advantageous to harsh environments and wireless network. We designed and fabricated the SAW strain sensor. The SAW strain sensor attached on a specimen was tested with a tensile tester. The strain on the sensor surface was measured with a commercial strain gauge and compared with that obtained from strain analysis. The central frequency shift of the SAW sensor was measured with a network analyzer. The sensitivity of the SAW strain sensor is 134 $Hz/{\mu}{\varepsilon}$ which is high compared to previous results.