• 한국방재학회:학술대회논문집
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• 2010.02a
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• pp.89.2-89.2
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• 2010

고속도로에서 주행속도가 높아지게 되면, 도로의 노면 상태에 따라 차량의 안전과 쾌적한 운전자의 환경이 변화될 수 있다. 이처럼 도로의 노면 상태를 결정하는 주된 인자는 도로의 평탄성과 소성변형에 의한 노면의 요철이라고 할 수 있다. 평탄하지 못한 도로를 자동차가 고속으로 주행하게 되면, 자동차의 속도에 의한 도로와의 마찰이 발생하여 자동차에는 매우 큰 흔들림이 발생하게 된다. 또한, 도로의 경우에도 자동차의 차축과 도로면에서 발생하는 충격에 의해 미세한 진동이 발생하게 된다. 그리고 광섬유 브래그 격자(FBG)센서는 외부에서 작용하는 매우 미세한 물리량에 의한 변화의 측정이 가능한 매우 우수한 계측 센서로 사용이 가능하기 때문에 온도보상형 광섬유진동센서를 제작하였고, 이를 고속도로 포장면의 평탄성 모니터링에 활용하고자 하였다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.791-794
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• 2010

고속도로에서 주행속도가 높아지게 되면, 도로의 노면 상태에 따라 차량의 안전과 쾌적한 운전자의 환경이 변화될 수 있다. 이처럼 도로의 노면 상태를 결정하는 주된 인자는 도로의 평탄성과 소성변형에 의한 노면의 요철이라고 할 수 있다. 평탄하지 못한 도로를 자동차가 고속으로 주행하게 되면, 자동차의 속도에 의한 도로와의 마찰이 발생하여 자동차에는 매우 큰 흔들림이 발생하게 된다. 또한, 도로의 경우에도 자동차의 차축과 도로면에서 발생하는 충격에 의해 미세한 진동이 발생하게 된다. 그리고 광섬유 브래그 격자(FBG)센서는 외부에서 작용하는 매우 미세한 물리량에 의한 변화의 측정이 가능한 매우 우수한 계측 센서로 사용이 가능하기 때문에 온도보상형 광섬유진동센서를 제작하였고, 이를 고속도로 포장면의 평탄성 모니터링에 활용하고자 하였다.

• Composites Research
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• v.13 no.5
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• pp.1-9
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• 2000

An intensity-based optical fiber vibration sensor is applied to monitor the structural vibration and detect impact locations on a plate. 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. For vibration sensing, optical fiber vibration sensor is mounted on the carbon fiber composite beam and its response is investigated to free and forced vibration. In impact location detection, four optical fiber vibration sensors whose location is predetermined are placed at chosen positions and the different arrival times of impact-generated vibration signal are recorded by an FFT analyzer. Impact location can be calculated from these time delays. Experimental results show that optical fiber vibration sensor signals coincide with gap sensor in vibration sensing. The precise location of impact can be detected on an acrylate plate.

• 대한공업교육학회지
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• v.34 no.1
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• pp.274-286
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• 2009

Fiber optic sensor is widely used in measuring acoustic and vibration. Especially interferometric sensors are more suitable to measure the acoustic signal. In this paper, a Fabry-Perot interferometric fiber optic sensor was used to measure flow induced vibration. This vibration also measured using an accelerometer, and the data was compared to one other. The venture, nozzle, drop barrel, and rapid expansion in the pipeline are the measuring objects. The flow rate is changed from 50 L/min to 150 L/min and the average flow velocity was about 7 m/s. Based on the experimental results the suggested fiber optic sensor detects flow induced vibration effectively. Therefore, this kind of fiber optic sensor can be applied to the monitoring the flow induced noise and vibration such as pipelines, cables, buildings.

• Composites Research
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• v.13 no.1
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• pp.89-97
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• 2000

Fatigue damage detection and vibration sensing for a laminated composites and impact location detection for a steel beam have been carried out using optical fiber sensor. Intensity based optical fiber sensor is constructed by placing two cleaved fiber end in a hollow glass tube, and multiple reflection within the cavity is considered. Fatigue signals are measured by embedded optical fiber, surface mounted optical fiber sensor and strain gage simultaneously. For vibration sensing, optical fiber sensor is mounted on the carbon fiber composite beam and its response to free vibration and forced vibration is investigated. In impact location detection, two optical fiber sensors are used and the information obtained from two sensors is arrival time delay of vibration caused by impact. Impact location can be calculated from this time delay. The obtained results show that the intensity based optical fiber sensor provide reliable data during long-term fatigue loading, unlike strain gage which deteriorate during the early part of the fatigue test. Optical fiber sensor signals coincide with gap sensor in vibration sensing. The precise locations of impact can be detected within 4.1% error limit.

• 대한공업교육학회지
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• v.32 no.2
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• pp.171-187
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• 2007

The purpose of this study is to measure the lathe tool vibration and verify its usefulness using the fiber optic interferometeric sensor instead of using common accelerometer. To compare two vibration signals a Fabry-Perot fiber optic sensor(FOS) is directly attached to the left-side surface of the lathe tool and an accelerometer is attached near to the fiber optic sensor. Measurement signals from the FOS and theoretical results of receptance simulation are compared. When the amplitude of tool vibration increased the frequency shift phenomena was occurred. This means that mass effect occurred and vibration spectrum moved to the low frequency region. Generally this results is agreement to the regenerative chatter. The chatter frequency is not same as the natural frequency of the tool itself. The FOS can also applied to laboratory experiments for students. This experimental technique is perhaps the first attempts because of directly attachment technique. Therefore, suggested Fabry-Perot fiber optic sensor can be used to monitoring the tool wear and vibration.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.1
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• pp.44-48
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• 2002

In this paper, we demonstrated the simultaneous measurment of triple parameters such as strain, temperature, and vibration using single FBG/EFPI hybrid sensor. The FBG/EFPI sensor system for the strain and temperature measurement and the EFPI sensor system for the the vibration measurement were combined by a wavelength division multiplexer. The optical source of FBG/ EFPI sensor system is a wavelength-swept fiber laser(WSFL) and that of an EFPI sensor system is a laser diode. We performed the simultaneous measurement of thermal strain, temperature, and vibration of a aluminum beam placed in a thermal chamber and validated the efficiency of the constructed measurment system.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.330-331
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• 2003

분포형 광섬유 센서시스템은 일정한 길이의 연속적인 광섬유 및 광케이블을 매질로 하여 길이 방향에서 생기는 투과율 또는 산란 특성의 변화를 통해 물리량의 변화와 그 위치를 감지하는 시스템을 말한다. 그 중에서 광섬유 내부의 브릴루앙 산란효과를 이용하여 광케이블 주위에 진동, 압력등에 매우 민감한 분포형 광섬유센서를 구성하고 외부로부터의 침입 유무와 위치를 파악함과 동시에 주요시설물의 감시 및 진단이 가능하도록 한다. (중략)

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.2
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• pp.135-141
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• 2004

We developed a polarimetric fiber-optic current sensor system for protective relaying usage. A fiber sensing coil that consisted of a length of twisted fiber and a FRM (Faraday rotator mirror) was used in order to suppress the linear birefringence effect. From the experiments with various sensing coil configurations and environmental conditions, the proposed current sensor system showed feasibility of suppressing environmental noises, and the obtained measurement stability was less than $\pm$3％ at rated primary current.

• Proceedings of the Optical Society of Korea Conference
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• 1988.06a
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• pp.112-116
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• 1988

Homodyne 방식으로 동작하는 광섬유 간섭계 센서는 주위 온도의 변화나 진동등에 의하여 시노의 크기가 불규칙하게 변화된다. 따라서 광섬유 간섭계가 직작조건에서 동작하도록 하여 감도를 최대로 유지시켜야 한다. 본연구에서는 원통형 압전자소자에 단일모드 광섬유룰 감아서 변환율 K=1.07$\pi$/V의 위상변조기를 만들고, 이를 이용하여 능동위상추적(active phase tracking)방식의 신호안정화 장치를 제작하고 광섬유 간섭계 센서의 공기중 읍압반응을 조사하였다.