• 대한기계학회논문집A
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• 제22권1호
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• pp.80-89
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• 1998

The measuring method of structural strain by a 3*3 passive-demodulated fiber optic interferometric sensor was developed to implement the real-time monitoring of structural status. A 3*3 fiber optic Michelson interferometric sensor was constructed to sense the value and the direction of structural strain. This sensor was applied on the cantilevered aluminum beam to experiment the sensing of the structural deformation. The digital signal processing was programmed by LabVIEW to determine the structural strain from the fiber optic signals. This program was verified by various simulated fiber optic signals. Finally, the structural was well determined by this developed program from real fiber optic signals.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.81-84
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• 2007

In this paper, fiber optic sound and vibration monitoring sensor which is latticed shape structure based on Sagnac interferometer is fabricated and tested in laboratory conditions. To detect external vibrations surface mounted fibers on the latticed steel wire fence with a dimension of 170cm by 180cm is used. To detect external sound frequency the tightened fiber optic itself wire netting fence with a dimension of 50cm by 50cm is used. Experiments for the detection of the excited vibration and sound signals were performed. A small vibrator induced external vibration signal and it is applied to the latticed structure in the range of 100Hz to several kHz. External sound signal applied to the fiber optic sensor net using non-directional sound speaker. The detected optical signals were compared and analyzed to the detected both accelerometer and microphone signals in the time and frequency domain. Based on the experimental results, distributed fiber optic sensor using Sagnac interferometer detected effectively external vibration and sound signal and had a good performance. This system can be expanded to the monitoring of a significant system and to the structural health monitoring system.

• 한국광학회지
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• 제12권4호
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• pp.289-293
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• 2001

금속 모세관을 이용하여 일반적인 단일모드 광섬유를 결합함으로써 매크로 벤딩(macro bending)을 측정할 수 있는 광섬유 센서를 제작하였다. 매크로 벤딩에 의한 곡률 반지름이 감소함에 따라 각도 정렬 오차가 증가하여 투과되는 빛의 에너지가 감소하게 되므로 매크로 벤딩을 측정할 수 있었다. 측정 범위는 곡률 반지름 20mm에서 85mm의 영역이었다. 사용한 광섬유 격자의 중심 파장은 각각 1543.3 nm, 1549.5nm이고 최대 벤딩 손실을 -11.19dB였다. 이 센서와 광섬유 브래그 격자를 이용하여 다중점 측정이 가능함을 보였다.

• 센서학회지
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• 제19권1호
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• pp.62-66
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• 2010

We have proposed and demonstrated a rotation angle sensor based on the stress -optic effect of a fused fiber coupler whose transmission spectrum is altered by the torsional stress. The peak of transmission spectrum was shifted to longer wavelength region with rotation of the coupler. The rotation angle sensor revealed reproducibility and symmetric behavior with respect to the rotation direction. The sensitivity of the sensor was 0.367 [nm/degee].

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.342-345
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• 2005

To detect external acoustic signal, fiber optic sensor array using Fabry-Perot interferometer which had benefit of minimize and light-weight was used. The sensor head has 1cm in length, total length of fiber is 9.5cm, and the sensor supported at both ends, simply. External sound applied in lateral direction and detected two signals were compared each other. It was confirmed that the Fabry-Perot interferometric sensor array detected acoustic signal, effectively.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.215-218
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• 2005

In this research, design scheme of fiber Bragg grating(FBG) sensor system for aircraft application is suggested from the results and the know-how from the fon11er researches on structural health monitoring techniques using fiber optic sensors. Design factors to be taken into consideration were derived for both sensor parts including connection and system parts. For the stability of FBG sensor system, design requirements of temperature, vibration, humidity, electromagnetic interference were presented from U. S. military standards. The direction of software programming which increases stability and perfon11ance of the aircraft with the FBG sensor system was also examined.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.772-777
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• 2008

Recent development of fiber optic sensors and wireless sensor technology, made structural health monitoring of railway structures cost effective. In this paper, a micro bending fiber optic rail pad sensors are evaluated for train axle force measurement. In order to assess the usability of FBG fiber optic sensors for short-term bridge measurement, the FBG sensors and conventional strain gauges are installed at the same points and the strain results are compared. Also the impact factors are calculated using the FBG strain responses and the results are compared with the conventional sensor responses. A running KTX train was instrumented with wireless sensor system to measure the vibration characteristics and the results are compared with conventional wire sensor system.

• 조명전기설비학회논문지
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• 제29권5호
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• pp.13-18
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• 2015

In this paper, we implemented a polarimetric vibration sensor using a Sagnac birefringence interferometer composed of polarization-maintaining photonic crystal fiber(PM-PCF). By changing the amplitude and frequency of vibration applied to PM-PCF employed as the sensor head of the proposed sensor, sensor responses to various types of vibration were investigated. First, the vibration characteristic of the sensor was explored for a single frequency in a frequency range from 1 to 3000Hz with a cylindrical piezoelectric transducer, and then the sensor response to naturally damped vibration was examined by utilizing a metal cantilever. It was experimentally observed that the sensor output signal was deteriorated by more than 3dB at ~1900Hz in the single frequency vibration measurement with a minimum detectable strain perturbation of ${\sim}1.34n{\varepsilon}/Hz^{1/2}$ at 1500Hz and the peak value of the sensor output signal was proportional to the strength of initially applied stress in the naturally damped vibration measurement.

• Journal of the Optical Society of Korea
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• 제17권4호
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• pp.312-316
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• 2013

A novel fiber-optic sensor system is suggested in which fiber Bragg grating sensors are demodulated by a wavelength-sweeping fiber laser source and a spectrometer. The spectrometer consists of a diffraction grating and a 512-pixel photo-diode array. The reflected Bragg wavelength information is transformed into spatial intensity distribution on the photo-diode array. The peak locations linearly correspond to the Bragg wavelengths, regardless of the nonlinearities in the wavelength tuning mechanism of the fiber laser. The high power density of the fiber laser enables obtaining high signal-to-noise ratio outputs. The improved demodulation characteristics were experimentally demonstrated with a fiber Bragg grating sensor array with 5 gratings. The sensor outputs were in much more linear fashion compared with the conventional tunable band-pass filter demodulation. Also it showed advantages in signal processing, due to the high level of photo-diode array signals, over the broadband light source system, especially in measurement of fast varying dynamic physical quantities.

• Composites Research
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• 제13권5호
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• pp.1-9
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• 2000

광강도형 광섬유 진동센서를 이용한 구조물의 진동감지 및 판에서의 충격위치 검출에 관한 연구가 수행되었다. 광섬유 진동센서는 유리 모세관의 내부에 광섬유의 클래딩 부분이 서로 마주보게 하여 제작되며 그 중 한 쪽은 외팔보 형태이다. 진동이 센서에 가해지면 센서 내부의 외팔보가 진동하게 되고 그에 따라 맞은편 광섬유로 전해지는 빛의 강도가 변화하게 된다. 진동감지 실험을 위해 광섬유 진동센서를 복합재료 보의 표면에 부착하고 자유 진동 및 강제 진동에 대한 신호를 취득하였다. 충격 위치 검출에 관한 실험은 아크릴 판에 대하여 알려진 위치에 네 개의 센서를 표면에 부착하고 진동의 도달 시간을 FFT를 이용하여 측정하였다. 충격위치는 이러한 시간차이를 이용하여 계산되어졌다. 광섬유 진동센서는 상용센서인 갭센서와 동일하게 구조물의 진동을 감지하였으며 판에서의 충격위치를 비교적 정확히 측정하였다.