• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.3
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• pp.218-221
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• 2009

This paper reports on measurement method for the fiber optic strain monitoring of overhead contact line systems of trains, We used FBG (Fiber Bragg Grating) sensors to measure the strain variation of overhead contact line. FBG sensors can sensitively measure the variation of strain and! or temperature by the shift wavelength of reflected wave according to the lattice variation during the measurement. FBG sensor were attached on the contact line and connected to the monitoring system with optical fibers. The monitering system with FBG sensors showed very good sensitivity to measuring strain variation and this system could be applied to the overhead contact line of KTX (Korea Train eXpress).

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.1-7
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• 2021

This study attempted to detect possible collapse and fire accidents in facilities for disaster monitoring of large facilities, and to develop a customized beacon to recognize the internal situation of an IoT-based facility when a disaster occurs. In the case of data measurement using the existing strain gauge sensor, the strain gauge sensor was connected by wire to measure it, but this study changed it to wireless so that the presence and absence of structural deformation can be monitored in real time. In this process, in order to use the Wheatstone bridge, a strain sensor module that can be connected to a customized beacon was manufactured, and a system configuration was conducted to remotely check the measurement data. To verify measurement data, 10 customized beacons and 2 gateways were installed on the 15th floor of the Advanced Institue of Convergence Technology, and as a result of analysis of measurement data, it was confirmed that the strain data values were distributed between 7 and 8.

• Journal of Advanced Navigation Technology
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• v.23 no.2
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• pp.200-206
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• 2019

The most frequent type of safety-accident in industry is the overturning of forklift. The leading cause of this accident is overload in forklift. Thus, it is needed to measure the weight on board of forklift. The most common method is based on load cell, and this method has the merit of high accuracy. However, high price is the disadvantage of this method. In this paper, we propose the new measurement system of the weight on board of forklift based on the strain gauge sensor, which has the disadvantage of low accuracy. The differentiation of the proposed system is that the shape of the strain gauge sensor customized for anchor bolt of forklift in order to improve the accuracy and durability. In system four strain gauge sensors are inserted into four anchor bolts. The test result shows that 1% error of measurement is obtained in the proposed anchor bolt type strain gauge sensors.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.1
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• pp.57-61
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• 2008

A tensile-strain measurement method is proposed based on Depolarized Guided Acoustic-wave Brillouin Scattering (DGAWBS). The effect of tensile-strain applied to an optical fiber is investigated experimentally, observing that the resonance spectrum increases the measurement accuracy of DGAWBS at the TR25 mode. This paper presents a simple structure as tensile-strain sensor using two analyzers after sensing fiber.

• Journal of Ocean Engineering and Technology
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• v.34 no.3
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• pp.194-201
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• 2020

In this study, an optical-fiber sensor was used to measure loads that could act in an environment similar to the loading conditions that exist in an actual pipe. The structure and the installation method of the optical-fiber strain sensor were applied considering the actual large pipe and the buried pipe environment. Load tests were performed using a displacement sensor and sandbags to determine the deflection of the pipe according to the external load, and the linear measurement results were verified. Considering the conditions that could exist in the actual pipe, the test method was presented, and the strain of the buried pipe generated at this time was measured.

• Journal of IKEEE
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• v.11 no.2
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• pp.77-82
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• 2007

This paper decribess the strain and temperature sensor using fiber optic surface plasmon resonance sensor. The sensor head is 3-layered, Cr, Ag, Au and we showed feasibility to use this sensor to measure strain and temperature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.300-301
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• 2014

Measurement of beam deflection is a common procedure to determine proper behavior of the structure. Either LVDT (Linear Variable Displacement Transformer) or strain gauge is usually used in experiments. A newly developed coordinate reading measurement system can be also applied for the deflection measurements. In this study, an experimental measurement was made on a laboratory size beam specimen to examine the possibility of the use of such coordinate measurement system. Results have shown the possibility of utilizing the new system for beam deflection measurement.

• Journal of the Optical Society of Korea
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• v.8 no.4
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• pp.168-173
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• 2004

Brillouin scattering-based fiber optic sensors are useful to measure strain or temperature in a distributed manner. Since the Brillouin frequency of an optical fiber depends on both the strain and temperature, it is very important to know whether the Brillouin frequency shift is caused by the strain change or temperature change. This article presents a temperature compensation technique of a Brillouin scattering-based fiber optic strain sensor. Both the changes of the Brillouin frequency and the Brillouin gain power is observed for the temperature compensation using a BOTDA sensor system. Experimental results showed that the temperature compensated strain values were highly consistent with actual strain values.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.135-139
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• 2001

This paper describes a string resonator that is used for the interrogation system of a Fiber Bragg Grating(FBG) strain sensor. The strain on the fiber piece is calculated from the measured frequency based on that the natural frequency of a string is a function of the applied absolute strain. Existing research considered a fiber as a string, but a fiber is not a string in the strict sense due to its bending stiffness, thus the fiber should be modeled as a beam accompanied with an axial force. In the vibration modeling, the relationship between the strain and the natural frequency is derived, and then the resonance condition is described in terms of both the phase and the mode shape for sustaining resonant motion. Several experiments verify the effectiveness of the proposed model of the fiber. The performance of the string resonator is analyzed by measuring the frequency change according to the applied strains in the dynamic range of 1100$\mu\varepsilon$ referred to the displacement from capacitance sensor. From the experimental results, the implemented string resonator provides the accuracy of $\pm$3$\mu\varepsilon$, the quasi-static resolution of ~0.1$\mu\varepsilon$(rms) which amount to be $\pm$0.17$\mu\textrm{m}$ and ~6nm respectively, in case of fiber length of 56mm. For a dynamic strain, it can provide the accuracy of ~3$\mu\varepsilon$ until the frequency comes to 8Hz. As a consequence, the string resonator proposed for FBG sensor provides the high accuracy and the high resolution in strain measurement, and also it is expecting to be used, for the application, to not only strain but also displacement measuring device.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.04a
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• pp.163-166
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• 2000

Fiber Bra99 grating (FBG) sensor, one of the fiber optic sensor (FOS) offers lots of advantages for structural health monitoring due to its multiplexing capability. Also, it is proper to measure the structural vibration with no mass concentration effect. In this paper, we constructed two sensor arrays composed of 9 FBG sensors for the vibration and mode sensing of a composites beam. For an accurate measurement of wavelength shift, a signal processing board with an electric circuit based on time-interval counting was developed. This sensor system showed a good resolution of dynamic strain (<10${\mu}{\varepsilon}$). Using this sensor system, dynamic strains at 9 points of composite beam was measured and strain measured mode shape of the beam was calculated from the acquired strains and compared with numerical results by ABAQUS.