• Title/Summary/Keyword: Glass Optical Fiber

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Strain Analysis in GFRP Cross-Ply Laminates Using TR-EFPI Optical Fiber Sensor (광섬유 TR-EFPI 센서를 이용한 GFRP 직교 적층판의 변형률 해석)

  • 우성충;최낙삼;권일범
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2003.10a
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    • pp.150-153
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    • 2003
  • Longitudinal strains({$varepsilon}_x$) of the core and skin layers in glass fiber reinforced plastic(GFRP) cross-ply composite laminates have been studied using the embedded optical fiber sensor of totally-reflected extrinsic Fabry-Perot interferometer(TR-EFPI). Foil-type strain gauges bonded on both the upper and lower surfaces were used for the measurement of the surface strains. Both TR-EFPI sensor and strain gauge bonded on the specimen surface showed excellent agreement within -0.0086 ~ +0.0302% strain. It was shown that values of {$varepsilon}_x$ in the interior of the surface layer and the core layer measured by embedded TR-EFPI sensor was significantly higher than that of the specimen surface measured by strain gauges. The experimental results were ascertained with finite element analysis. Embedded TR-EFPI optical fiber sensor could measure accurately the internal strains which were different from the surface.

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Acoustic Emission Characteristics during fracture Process of Glass Fiber/Aluminum Hybrid Laminates (유리섬유/알루미늄 혼합 적층판의 파괴과정과 음향방출 특성)

  • Woo, Sung-Choong;Choi, Nak-Sam
    • Journal of the Korean Society for Nondestructive Testing
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    • v.25 no.4
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    • pp.274-286
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    • 2005
  • Fracture behaviors and acoustic emission (AE) characteristics of single-edge-notched monolithic aluminum plates and glass fiber/aluminum hybrid laminate plates have been investigated under tensile loads. AE signals from monolithic aluminum could be classified into two different types: signals with low frequency band and high frequency band. High frequency signals were detected in the post stage of loading beyond displacement of 0.45mm. For glass fiber/aluminum laminates, AE signals with high amplitude and long duration were additionally confirmed on FFT frequency analysis, which corresponded to macro-crack propagation and/or delamination between A1 and fiber layers. On the basis of the above AE analysis and fracture observation with optical microscopy and ultrasonic T scan, characteristic features of AE associated with fracture processes of single-edge-notched glass fiber/aluminum laminates were elucidated according to different fiber ply orientations.

Effect of Inorganic Fillers on the Dimensional Stability of Poly(ethylene naphthalate) Film as a Flexible Substrate (무기 필러가 유연기판용 폴리에틸렌나프탈레이트 필름 치수안정성에 미치는 영향)

  • Kim, Jongwha;Kim, Hongsuk;Kang, Ho-Jong
    • Polymer(Korea)
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    • v.36 no.6
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    • pp.733-738
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    • 2012
  • The effect of glass bead and glass fiber on the enhancement of dimensional stability in poly(ethylene naphthalate) (PEN) flexible substrate for photovoltaic devices has been studied. It was found that the coefficient of thermal expansion (CTE) and the optical transmittance decreased with increasing inorganic filler content. In addition to filler contents, the size and size distribution of fillers are the other important factors to improve CTE and optical transmittance of PEN film. Our results showed that the optimum filler content was found to be about 5 wt% to enhance the dimensional stability of PEN by more than 50% with maintaining the optical transmittance over 85% for the flexible substrate.

Design and characteristics of a fiber-optic pressure sensor (광압력 센서의 설계 및 특성)

  • Kim, Young-Soo;Kim, Yo-Hee;Strigalev, V. E.
    • Proceedings of the KIEE Conference
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    • 1995.11a
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    • pp.508-510
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    • 1995
  • A fiber-optic pressure sensor is fabricated with a photoelastic glass material. To remove the influence of external pertubation along the optical fiber, a new referencing technique is proposed by using two light sources. LED with 870nm wavelength is used as light source for reference signal, and LED with 660nm wavelength is used as light source for modulation signal. The fiber-optic pressure sensor system shows good linearity within the pressure range of 0 to 5 $kg/cm^2$.

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Vibration Sensing and Impact Location Measurement Using Intensity-Based Optical Fiber Vibration Sensor (광강도형 광섬유 진동센서를 이용한 진동감지 및 충격위치 측정)

  • 양유창;황운봉;박현철;한경섭
    • 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.

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Fabrication and characterization of integrated optic wavelength demultiplexer using a chirped grating (Chirped 회절격자를 이용한 집적형 파장분할 다중화기 제작 및 특성 측정)

  • 서만수
    • Proceedings of the Optical Society of Korea Conference
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    • 1990.02a
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    • pp.232-236
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    • 1990
  • Optical waveguide was fabricated in the soda lime glass substrate using rapid thermal method. A chirped grating having period variation of 0.41 - 0.51${\mu}{\textrm}{m}$ on this waveguide for WDM was made. And then, arranging input and output optical fiber, wavelength division multiplexer with 5 channels in short wavelength region was realized. Experiment result of this WDM showed that wavelength spacing, 3 dB bandwidth, insertion loss and crosstalk were 5nm, 4nm, 40dB and less than -10dB, respectively.

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Fiber Optic Smart Monitoring of Concrete Beam Retrofitted by Carbon and Glass Sheets

  • Kim Ki-Soo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.05a
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    • pp.486-489
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    • 2004
  • In this paper, we try to detect the peel out effect and find the strain difference between the main structure and retrofitting patch material when they separate from each other. In the experiment, two fiber optic Bragg grating sensors are applied to the main concrete structure and the patching material separately at the same position. The sensors show coincident behaviors at the initial loading, but different behaviors after a certain load. The test results show the possibility of optical fiber sensor monitoring of beam structures retrofitted by the composite patches.

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Fabrication of Optical Fiber Preform by MCVD Method (MCVD법을 이용한 광섬유 모재의 제작)

  • 이기완;홍봉식
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.14 no.4
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    • pp.307-320
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    • 1989
  • This paper presetns new design of the Modified Chemical Vapor Deposition(MCVD) system for optical fiber preform fabrication. It contains a glass working lathe, raw material supplier and exhaust gas treatment apparatus as fundamental instruments for MCVD process, graded index fiber design, characteristic of process and the experimenta arrangement to measure the refractive index profile of MCVD preforms, respectively. From the investigation results, it is shown that an ideal graded index fiber preform does not exhibit a center dip or bump.

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Cooling Speed Effects of Fluoride Glasses (불화 유리의 냉각 속도 효과)

  • 류선윤
    • Journal of the Korean Ceramic Society
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    • v.32 no.2
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    • pp.183-188
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    • 1995
  • The properties of the glasses are not dominantly dependent on the chemical composition, temperature, and pressure but also on the thermal history. For example, electrical, thermal, optical, and mechanical properties are all known to be strongly dependent on the thermal history. Fluoride glasses have received a great deal of attention as candidate materials for an infra-red transmitting medium. A series of fluoride glasses and fibers were prepared under a nitrogen atmosphere. Thermal history effects of the fluoride glass fibers associated with the fast cooling rate employed during the fiber drawing process were discussed in terms of the glass temperatures and the fictive temperatures on the basis of the results obtained from the Differential Scanning Calorimeter (DSC) measurements of the fiber and bulk forms of the same chemical composition.

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Fiber-optic Mach-Zehnder Interferometer for the Detection of Small AC Magnetic Field (미소 교류 자기장 측정을 위한 Mach-Zehnder 광섬유 간섭계 자기센서 특성분석)

  • 김대연;안준태;공홍진;김병윤
    • Korean Journal of Optics and Photonics
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    • v.2 no.3
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    • pp.139-148
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    • 1991
  • A fiber-optic magnetic sensor system for the detection of small ac magnetic field(200Hz-2 kHz) was constructed. Magnetic field sensing part was fabricated by bonding a section of optical fiber to amorphous metallic glass(2605SC) having large magnetostriction effect. And with the directional coupler, all fiber type Mach-Zehnder interferometer was constructed to measure the variation of the external magnetic field by translating it into the optical phase shift in the interferometer. The signal fading problem of the interferometer, which is due to random phase drifts originated from the environment, i.e., temperature fluctuation, vibrations, etc., was elliminated by feedback phase compensation. This allows the sensitivity to be maintained at the maximum by keeping the interferometer in quadrature phase condition. The frequency response of metallic glass was found to be nearly flat in the range of 90 Hz-2 kHz and dc bias field for the maximum ac response was 3.5 Oe. The interferometer output showed good linearity over the range $\pm$0.5 Oe. For 1 kHz ac magnetic field the scale factor S and the minimum detectable magnetic field were measured to be 8.0 rad/Oe and $3X10^{-6} Oe/\sqrt{Hz}$at 1 Hz detection bandwidth respectively.

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