• 제목/요약/키워드: distributed optic fiber

Search Result 70, Processing Time 0.025 seconds

Health Monitoring Technology using Optic Fibre Sensors for Ships and Marine Equipment (광섬유센서를 이용한 선박 및 해양기자재의 안전진단 기술)

  • Lee, Sei-Chang;Kim, Jong-Ho;Kim, Jung-Yul;Kim, Yoo-Sung
    • Proceedings of the Korean Society of Marine Engineers Conference
    • /
    • 2006.06a
    • /
    • pp.275-276
    • /
    • 2006
  • 선박 및 해양기자재의 안전 진단을 위한 기존의 기술은 접 센서(point sensor)를 이용한 변형률 측정 기술이 대부분이라 할 수 있다. 본 논문은 기존의 기술보다 효율적으로 응용될 수 있는 광섬유 센서를 이용한 분포 개념의 온도 및 변형률 측정(DTSS: Distributed Temperature & Strain Sensing) 기술에 대해 소개하고 있다. 이 기술은 선체 응력 모니터링, 해양 구조물 안전진단, subsea flowline 모니터링, platform의 riser 안정성, umbilical 모니터링 등에 활용될 수 있다.

  • PDF

Measurement of Brillouin Backscattering for Distributed Temperature Sensor Applications

  • Kim, Su-Hwan;Kwon, Hyung-Woo;Kwon, Hyun-Ho;Jang, Hang-Seok;Kim, Jee-Hyun;Kang, Shin-Won
    • Journal of Sensor Science and Technology
    • /
    • v.20 no.1
    • /
    • pp.8-13
    • /
    • 2011
  • We present measurements of the Brillouin frequency shift in an optical fiber using a 1550 nm distributed feedback laser diode(DFB-LD) as a light source. By modulating the probe light with an electro-optic modulator, we confirm the stimulated Brillouin gain spectrum(BGS) and spontaneous BGS using the coherent detection method. We also confirm the applicability of the technique to distributed temperature sensors that measure the change in Brillouin frequency shift due to temperature variations.

Case Studies on Distributed Temperature and Strain Sensing(DTSS) by using an Optical fiber (광섬유 센서를 이용한 온도 및 변형 모니터링에 대한 현장응용 사례)

  • Kim, Jung-Yul;Kim, Yoo-Sung;Lee, Sung-Uk;Min, Kyoung-Ju;Park, Dong-Su;Pang, Gi-Sung;Kim, Kang-Sik
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2006.03a
    • /
    • pp.86-95
    • /
    • 2006
  • Brillouin backscatter is a type of reflection that occurs when light is shone into an optical fibre. Brillouin reflections are very sensitive to changes in the fibre arising from external effects, such as temperature, strain and pressure. We report here several case studies on the measurement of strain using Brillouin reflections. A mechanical bending test of an I beam, deployed with both fiber optic sensors and conventional strain gauge rosettes, was performed with the aim of evaluating: (1) the capability and technical limit of the DTSS technology for strain profile sensing; (2) the reliability of strain measurement using fiber optic sensor. The average values of strains obtained from both DTSS and strain gauges (corresponding to the deflection of I beam) showed a linear relationship and an excellent one-to-one match. A practical application of DTSS technology as an early warning system for land sliding or subsidence was examined through a field test at a hillside. Extremely strong, lightweight, rugged, survivable tight-buffered cables, designed for optimal strain transfer to the fibre, were used and clamped on the subsurface at a depth of about 50cm. It was proved that DTSS measurements could detect the exact position and the progress of strain changes induced by land sliding and subsidence. We also carried out the first ever distributed dynamic strain measurement (10Hz) on the Korean Train eXpress(KTX) railway track in Daejeon, Korea. The aim was to analyse the integrity of a section of track that had recently been repaired. The Sensornet DTSS was used to monitor this 85m section of track while a KTX train passed over. In the repaired section the strain increases to levels of 90 microstrain, whereas in the section of regular track the strain is in the region of 30-50 microstrain. The results were excellent since they demonstrate that the DTSS is able to measure small, dynamic changes in strain in rails during normal operating conditions. The current 10km range of the DTSS creates a potential to monitor the integrity of large lengths of track, and especially higher risk sections such as bridges, repaired track and areas at risk of subsidence.

  • PDF

Monitoring of a CFRP-Stiffened Panel Manufactured by VaRTM Using Fiber-Optic Sensors

  • Takeda, Shin-Ichi;Mizutani, Tadahito;Nishi, Takafumi;Uota, Naoki;Hirano, Yoshiyasu;Iwahori, Yutaka;Nagao, Yosuke;Takeda, Nobuo
    • Advanced Composite Materials
    • /
    • v.17 no.2
    • /
    • pp.125-137
    • /
    • 2008
  • FBG (Fiber Bragg Grating) sensors and optical fibers were embedded into CFRP dry preforms before resin impregnation in VaRTM (Vacuum-assisted Resin Transfer Molding). The embedding location was the interface between the skin and the stringer in a CFRP-stiffened panel. The reflection spectra of the FBG sensors monitored the strain and temperature changes during all the molding processes. The internal residual strains of the CFRP panel could be evaluated during both the curing time and the post-curing time. The temperature changes indicated the differences between the dry preform and the outside of the vacuum bagging. After the molding, four-point bending was applied to the panel for the verification of its structural integrity and the sensor capabilities. The optical fibers were then used for the newly-developed PPP-BOTDA (Pulse-PrePump Brillouin Optical Time Domain Analysis) system. The long-range distributed strain and temperature can be measured by this system, whose spatial resolution is 100 mm. The strain changes from the FBGs and the PPP-BOTDA agreed well with those from the conventional strain gages and FE analysis in the CFRP panel. Therefore, the fiber-optic sensors and its system were very effective for the evaluation of the VaRTM composite structures.

Fiber Optic Sensor for the Detection of Abnormal Structural Signals from Various Constructions (구조물 이상탐지용 광섬유 센서)

  • Kwon, Il-Bum;Lee, Youn-Jae;SeoMoon, Ung;Jo, Jae-Heung
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.10 no.6 s.52
    • /
    • pp.133-135
    • /
    • 2006
  • We propose and fabricate a novel fiber optic sensor for the detection of abnormal structural signals from various constructions. It's advantages are highly sensitive. small in dimension and electro-magnetic immune. Since this sensor was simply constructed with a single-mode fiber at infra-red wavelength and a laser-diode with the wavelength of 625 nm, the modes in the end of the optical fiber were not show as Gaussian distributed. So, we used the change of the mode distribution to get the sensor output by the external abnormal effect of structures. We investigated the resonance by performing the bending test of an aluminum beam attached with the fiber sensor. In the test, we could obtained a feasible signal to sense the abnormal condition of structures.

New theorical modeling for diagnosis of power cable using optic fiber (광화이버를 이용한 전력케이블 진단을 위한 새로운 이론적 모델링)

  • Kim, Tae-Sun;Seo, Chul-Hun
    • Proceedings of the KIEE Conference
    • /
    • 1998.07e
    • /
    • pp.1837-1839
    • /
    • 1998
  • This paper proposes the strain-insensitive temperature sensing in quasi-distributed sensor system using different thermal expension coefficient materials. This system has the high sensitivity and hasn't the necessity of reference signal. We can monitor the condition of the power cable with this system.

  • PDF

Fabrication optimization of Fiber Bragg gratings (광섬유 브래그 격자(Fiber Bragg grating) 제작과 제작 조건에 따른 특성 향상)

  • Choi, Bo-Hun
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.14 no.7
    • /
    • pp.1680-1686
    • /
    • 2010
  • Optical fiber Bragg grating to have the lowest transmitivity at 1549.9nm wavelength was fabricated using a Gaussian distributed KrF Eximer laser of 248nm lasing wavelength and a phase mask of 1.072um period. The proper alignment of an optic setup to fabricate fiber gratings was investigated and the reproductivity of the grating fabrication was examined using the obtained optimum fabrication condition in this experiment.

Performance evaluation of soil-embedded plastic optical fiber sensors for geotechnical monitoring

  • Zhang, Cheng-Cheng;Zhu, Hong-Hu;Shi, Bin;She, Jun-Kuan;Zhang, Dan
    • Smart Structures and Systems
    • /
    • v.17 no.2
    • /
    • pp.297-311
    • /
    • 2016
  • Based on the distributed fiber optic sensing (DFOS) technique, plastic optical fibers (POFs) are attractive candidates to measure deformations of geotechnical structures because they can withstand large strains before rupture. Understanding the mechanical interaction between an embedded POF and the surrounding soil or rock is a necessary step towards establishing an effective POF-based sensing system for geotechnical monitoring. This paper describes a first attempt to evaluate the feasibility of POF-based soil deformation monitoring considering the POF-soil interfacial properties. A series of pullout tests were performed under various confining pressures (CPs) on a jacketed polymethyl methacrylate (PMMA) POF embedded in soil specimens. The test results were interpreted using a fiber-soil interaction model, and were compared with previous test data of silica optical fibers (SOFs). The results showed that the range of CP in this study did not induce plastic deformation of the POF; therefore, the POF-soil and the SOF-soil interfaces had similar behavior. CP was found to play an important role in controlling the fiber-soil interfacial bond and the fiber measurement range. Moreover, an expression was formulated to determine whether a POF would undergo plastic deformation when measuring soil deformation. The plasticity of POF may influence the reliability of measurements, especially for monitored geo-structures whose deformation would alternately increase and decrease. Taken together, these results indicate that in terms of the interfacial parameters studied here the POF is feasible for monitoring soil deformation as long as the plastic deformation issue is carefully addressed.

A study on the optical fiber diagnostics using rayleigh back-scattering (Rayleigh 억신란광을 이용한 광파이비 진단에 관한 연구)

  • Kim, Y.H.;Oh, S.K.;Kim, I.S.;Park, H.S.;Roh, J.D.;Kim, Y.S.
    • Proceedings of the KIEE Conference
    • /
    • 1997.07e
    • /
    • pp.1890-1892
    • /
    • 1997
  • In this paper, we have designed and fabricated high speed signal processing unit, optical driver and sensing unit in order to develop a distributed optic fiber sensing and measuring system using the rayleigh backscattering. To define the functions, we have constructed a testing system(1.1[km]), done the characteristics test.

  • PDF

The Accuracy Improvement of FBG Temperature Sensor by using Wavelet Transform (웨이블릿 변환을 이용한 광섬유 격자 온도센서의 정밀도 개선)

  • Cho, Yo-Han;Kim, Hyun-Jin;Song, Min-Ho
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.25 no.5
    • /
    • pp.73-78
    • /
    • 2011
  • We developed a noise reduction algorithm for the measurement accuracy improvement of a fiber-optic distributed temperaure sensor system. The denoising technique is based on the wavelet transform. The proposed algorithm was applied to a FBG sensor output with the Gaussian line-fitting algorithm to minimize the output noise which originated from the intensity noise of the laser light source and the instability of signal porcessing. We confirmed the feasibility of the denoising algorithm by comparing the measurement results with those obtained with the Gaussian line-fitting algorithm only.