• The Journal of the Acoustical Society of Korea
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• v.21 no.7
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• pp.614-623
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• 2002

In this paper, it was manufactured an interferometric optical fiber sensor and measured partial discharge acoustic signal caused by defect of power facilities such as power cables, transformers and gas insulation. Acrylic and aluminium mandrels wound with fiber-optic were chosen as optical fiber sensor, Sagnac and Mach-Zehnder interferometers were chosen to detect discharge acoustic signals. The two fiber optic interferometers were identified by using the PZT. Discharge experimentation set in the discharge imitation cell in oil tank and the discharge phenomena was generated. Based on the experimental result, to detect the discharge acoustic signal, Sagnac interferometer can detect stably the acoustic signal than the Mach-Zehnder interferometer. It is shown that Sagnac optical fiber sensor can detect the discharge acoustic signals effectively.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.161-164
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• 2002

Optical fiber vibrations sensors (OFVSs) and extrinsic Fabry-Perot interferometer (EFPI) were used in damage monitoring of fiber-metal laminates(FML). The optical fiber vibration sensor and EFPI were applied in order to detect and evaluate the strain, damage and failure of FML. Damages in composites, such as matrix cracks, delamination and fiber breakage may occur as a result of excessive load, fatigue and low-velocity impacts. Tensile test was performed with the measurement of optical signal and acoustic emission (AE). The signals of the optical fiber vibration sensor due to damages were quantitatively evaluated by wavelet transform. EFPI was less sensible to the damage signals compared with the optical fiber vibration sensor. It was found that damage information of comparable in quality to acoustic emission data could be obtained from the optical fiber vibration sensor signals.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.5
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• pp.956-962
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• 2008

We propose the optical CDMA based audio acoustic sensor using optical fiber sensors which can be used in the bottom of the sea. In the proposed network, we analyzed the performance of noise power. Numerical simulations confirm that the performance can be improved by increasing the measuring time of optical sensors compared with using conventional WDMA method.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.370-375
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• 2003

Optical fiber vibrations sensors (OFVSs) and extrinsic Fabry-Perot interferometer (EFPI) were used in damage monitoring of fiber-metal laminates(FML). The optical fiber vibration sensor and EFPI were applied in order to detect and evaluate the strain, damage and failure of FML. Damages in composites, such as matrix cracks, delamination and fiber breakage may occur as a result of excessive load, fatigue and low-velocity impacts. Tensile and indentation test was performed with the measurement of optical signal and acoustic emission (AE). The signals of the optical fiber vibration sensor due to damages were quantitatively evaluated by wavelet transform. It was found that damage information of comparable in quality to acoustic emission data could be obtained from the optical fiber vibration sensor signals.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.42-45
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• 2003

Optical fiber vibrations sensors (OFVSs) and extrinsic Fabry-Perot interferometer (EFPI) were used in damage monitoring of fiber-metal laminates(FML). The optical fiber vibration sensor and EFPI were applied in order to detect and evaluate the strain, damage and failure of FML. Damages in composites, such as matrix cracks, delamination and fiber breakage may occur as a result of excessive load, fatigue and low-velocity impacts. Indentation test was performed with the measurement of optical signal and acoustic emission (AE). The signals of the optical fiber vibration sensor due to damages were quantitatively evaluated by wavelet transform. It was found that damage information of comparable in quality to acoustic emission data could be obtained from the optical fiber vibration sensor signals.

• The Journal of the Acoustical Society of Korea
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• v.19 no.3
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• pp.92-99
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• 2000

In this paper, theoretical acoustic sensitivity was derived to describe acousto-optic transduction property of the mandrel type fiber optic acoustic sensor with respect to external acoustic field. The acoustic sensitivity was analyzed in relation to both material properties and geometrical influence factors of the constitutional parts of the sensor, analytically. Validity of the theoretical results were verified through comparison with the finite element analysis results. The variation trends of the sensitivity of the sensor in relation to the studied parameters showed good agreement for the two analysis methods. According to the results, it is considered more economical to design the basic structure of the sensor with the analytic equations developed in this paper, and then to carry out further detailed analysis with the finite element method for specific points of design interest.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.254-257
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• 2001

An intensity-based optical fiber vibration sensor is applied to detect and evaluate damages and fiber failure of composites. The optical fiber vibration sensor is constructed by placing two cleaved fiber end, one of which is cantilevered in a hollow glass tube. The movement of the cantilevered section lags behind the rest of the sensor in response to an applied vibration and the amount of light coupled between the two fibers is thereby modulated. Vibration characteristics of the optical fiber vibration sensor are investigated. Surface mounted optical fiber vibration sensor is used in tensile and indentation test. Experimental results show that the optical fiber sensor can detect damages and fiber failure of composites correctly.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.547-552
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• 2001

An intensity-based optical fiber vibration sensor is applied to detect and evaluate damages and fiber failure of composites. The optical fiber vibration sensor is constructed by placing two cleaved fiber end, one of which is cantilevered in a hollow glass tube. The movement of the cantilevered section lags behind the rest of the sensor in response to an applied vibration and the amount of light coupled between the two fibers is thereby modulated. Vibration characteristics of the optical fiber vibration sensor are investigated. Surface mounted optical fiber vibration sensor is used in tensile and indentation test. Experimental results show that the optical fiber sensor can detect damages and fiber failure of composites correctly.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.169-174
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• 2006

The outstanding mechanical property of optical fiber and the merits of acoustic emission sensing technique are unified for novel sensor system. The generated ultrasonic wave from piezoelectric generator are propagated along the optical fiber and also sensed. The propagated wave can be influence by external pressure on the optical fiber or environmental circumstance. The optical fiber sensor using ultrasonic wave has advantages compare with existing sensor system. In this study, the sensitivity of the optical fiber sensor is experimentally investigated. As the applications of the optical fiber sensor system using piezoelectric ultrasonic waves, the point load on the optical fiber is measured and the monitoring system for the void fraction of two phase flows is developed. The experimental results show the linear relationship between sensed voltage and void fraction.

• Current Optics and Photonics
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• v.1 no.6
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• pp.573-578
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• 2017

Position estimation of a sound source based on time difference of arrival at an array of three acousto-optic sensors is introduced. Each sensor consists of a Mach-Zehnder interferometer including a sensing part in one arm that is a piece of fiber surrounded by membrane in order to enhance the acousto-optic effect. Estimation error of a recorded gunshot sound signal was evaluated with the theoretically calculated values for two different locations.