• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1983.10a
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• pp.44-47
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• 1983

Through intensity modulation induced by micro bending of an optical fiber, a sensor detects the pressure and frequency of acoustic wave has been implemented. Axial slots on the cylinder suface with a period of 5.5 mm induce efficient microbending of the fiber, and a rubber sleeve covering the fiber enhances the fiber. Compared with a conventional hydrophone, it has a low minimum detectable pressure and can detect acoustic wave in 100Hz - 2KHz range.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.393-398
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• 2004

This paper is focused on practical applicability of the optical fiber sensor considering the machine center which is going to use them. Optical fibers may be fluctuated because the machine center operates as column moving type. This causes distortion of the sensor output signal. To reduce this problem, we have improved the sensor structure and its bracket. And we evaluated performances of the sensor.

• International Journal of Concrete Structures and Materials
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• v.3 no.1
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• pp.33-37
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• 2009

Fiber Bragg grating (FBG) sensors already have been the focus for structural health monitoring (SHM) due to their distinguishing advantages. However, as bare optical fiber is very fragile, bare FBG strain sensor without encapsulation can not properly be applied in practical infrastructures. Therefore encapsulation techniques for making encapsulated FBG strain sensor show very important in pushing forward the application of FBG strain sensors in SHM. In this paper, a simplified approximate method to analyze the stress transferring rules for embedded FBG strain sensors in concrete monitoring is put forward according to mechanics of composite materials. Shear lag theory is applied to analyze the stress transferring rule of embedded FBG strain sensor in measured host material at the first time. The measured host objects (concrete) and the encapsulated FBG strain sensor are regarded as a composite, and then the stress transfer formula and stress transfer coefficient of encapsulated FBG strain sensor are obtained.

• Journal of Sensor Science and Technology
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• v.19 no.3
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• pp.184-190
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• 2010

In this paper, a remote submersion warning system based on multi-mode optical fiber(MMF) sensors and a wireless sensor network(WSN) are proposed. To improve the reliability and stability of the sensors, the dual optical fiber sensors combined to the optical coupler are demonstrated. A slave zigbee as a wireless sensor module was used as a platform to monitor and record the signal from the MMF sensors and then transmits these information to a master zigbee wirelessly. The monitoring system running the $LabVIEW^{(R)}$ software was connected to the internet to support the short message service(SMS) through extensible markup language(XML) web service. No matter where the managers are, they can always receive the real-time remote-monitoring data for safety check.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.617-619
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• 2022

An embedded fiber-optic sensor was manufactured using 3D printing technology for distributed structural monitoring. Strain distribution of the embedded sensor was measured by the optical frequency domain reflectometry, and real-time data visualization for the embedded sensor model was demonstrated.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1874-1876
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• 1997

A fiber optic voltage sensor using photoelastic effect of a single-mode optical fiber, excited with a 632.8 nm He-Ne laser, is developed. The photoelastic effect is produced by piezoelectric effect for the voltage measurement. It is found that the detector output voltage is proportional to the applied voltage. Also, the frequency of the output voltage is equal to that of the applied voltage. Experimental results from a laboratory model demonstrate the feasibility of the sensor for field application in high-voltage systems.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.6
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• pp.72-76
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• 2003

We developed a polarimetric fiber-optic current sensor using a length of twisted fiber and a Faraday rotator mirror which was used to suppress the linear birefringence effect. A gold coated mirror was also used as the sensor coil reflector, and the results were compared with the case of FRM. From the experimental results, it is clear that the FRM greatly enhances the stability of the fiber optic current sensor output..

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.1123-1125
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• 1999

In this paper, we report a new scheme of multimode fiber sensor which uses pattern matching method. Fiber speckle pattern allows the wide dynamic range of the intensity based sensor. The proposed method uses pre-built specklegram database which is made by image processing techniques of wavelet transform and edge detection for the sake of compact data storage and fast sensing time. We demonstrate our proposed sensor and the experimental results will do presented.

• Journal of Sensor Science and Technology
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• v.18 no.3
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• pp.226-233
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• 2009

In this study, the optical properties of localized surface plasmon resonance sensor using optical fiber was analyzed as the variation of a size and surface density of gold nano particles on the etched optical fiber surface. It is shown that a size and surface density of gold nano particles on optical fiber surface are controlled by $Na_3$ citrate quantity and pH of gold colloid solution. To measure the sensitivity, peak wavelength of absorbance spectrum was detected as the reflective index of the solution. The sensor sensitivity is linearly dependent on the size and surface densities of gold nano particles from the results of optical experiments.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.579-587
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• 1998

In this study, fatigue behavior of the optical fiber sensor embedded in composite laminate was investigated. Static tensile and fatigue tests were performed for three types of laminated composite specimens with embedded optical fiber sensor in the neutral plane ; [0/sub 6//OF/0/sub 6/]/sub T/, [0/sub 2//90/sub 4//OF/90/sub 4//0/sub 2/]/sub T/ and [0/sub 3//90/sub 3//OF/90/sub 3//0/sub 3/]/sub T/. The fracture of the embedded optical fiber sensor was detected by the intensity drop off of laser signal transmitted through the optical fiber sensors embedded within laminated composite specimen. The maximum fatigue stress applied to laminated specimen was compared with the average tensile stress at which the fracture of the embedded optical fiber within the laminate occurred under static tensile loading. From the experiments, firstly it is observed that the decrease in the life of optical fiber sensors embedded within unidirectional-ply laminate by the fatigue loading is relatively small compared to that of cross-ply laminate. Secondly, the optical fiber embedded in unidirectional-ply laminate is fractured by the fatigue damage due to the growth of internal defects of optical fiber, however the optical fiber embedded in cross-ply laminate is fractured by the growth of transverse matrix crack.