• Title, Summary, Keyword: 변위

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Multiplexed Bend Loss Type Single-Mode Fiber-Optic Displacement Sensor Using Reflection Signals Generated at Optical Connectors (광커넥터의 반사를 이용한 다중화된 굽힘 손실형 단일모드 광섬유 변위센서)

  • Yoo Jung-Ae;Jo Jae Heung;Kwon Il-Bum
    • Korean Journal of Optics and Photonics
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    • v.15 no.5
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    • pp.415-422
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    • 2004
  • We propose and present a new multiplexed bend loss type single-mode fiber-optic sensor system for displacement measurement in order to measure the displacement of several mm of civil engineering structures such as bridges and buildings. We make a bend loss type fiber-optic sensor for measuring displacements using the signal difference between two reflection signals due to various bend losses generating at a pair of optical connectors by using the optical time domain reflectometer. And we fabricate a multiplexed bend loss type fiber-optic sensor detecting linear displacements of 4 measuring positions of an object by setting these new 4 fiber-optic sensors on a single mode fiber simultaneously. We find that the multiplexed fiber-optics displacement sensor has linearity of 0.9942, maximum displacement of 6 mm, and accuracy of 6% for 4 measuring points.

Real-Time Rendering of a Displacement Map using an Image Pyramid (이미지 피라미드를 이용한 변위 맵의 실시간 렌더링)

  • Oh, Kyoung-Su;Ki, Hyun-Woo
    • Journal of KIISE:Computer Systems and Theory
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    • v.34 no.5_6
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    • pp.228-237
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    • 2007
  • displacement mapping enables us to add realistic details to polygonal meshes without changing geometry. We present a real-time artifacts-free inverse displacement mapping method. In each pixel, we construct a ray and trace the ray through the displacement map to find an intersection. To skip empty regions safely, we traverse the image pyramid of displacement map in top-down order. Furthermore, when the displacement map is enlarged, intersection with bilinear interpolated displacement map can be found. When the displacement map is at distance, our method supports mipmap-like prefiltering to enhance image quality and speed. Experimental results show that our method can produce correct images even at grazing view angles. Rendering speed of a test scene is over hundreds of frames per second and the influence of resolution of displacement map to rendering speed is little. Our method is simple enough to be added to existing virtual reality systems easily.

Displacement and Velocity Dependence of Clamped Shape Metallic Dampers (꺽쇠형 강재 댐퍼의 변위 및 속도 의존성)

  • Lee, Hyun Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.2
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    • pp.62-70
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    • 2013
  • The purpose of this study is the displacement and velocity dependence evaluation of clamped shape metallic damper, which were evaluated superior in energy dissipation capacity than straight type slit damper. For this purpose, 6 metallic damper specimens are prepared and dependence test are performed. Test variables are displacement dependence and velocity dependence. According to displacement dependence test results, larger target displacement (50mm) shows lower cyclic numbers and cumulated energy dissipated area than lower target displacement (25mm). Also it shows higher strength and early failure than short target displacement. In velocity dependence evaluation, fast target velocity (60mm/sec) shows lower cyclic numbers and cumulated energy dissipated area than slow target velocity (40mm/sec). Therefore the hysteresis dependence of metallic damper were evaluated as close relation to the loading displacement and velocity conditions.

Vision-Based Displacement Measurement System Operable at Arbitrary Positions (임의의 위치에서 사용 가능한 영상 기반 변위 계측 시스템)

  • Lee, Jun-Hwa;Cho, Soo-Jin;Sim, Sung-Han
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.18 no.6
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    • pp.123-130
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    • 2014
  • In this study, a vision-based displacement measurement system is developed to accurately measure the displacement of a structure with locating the camera at arbitrary position. The previous vision-based system brings error when the optical axis of a camera has an angle with the measured structure, which limits the applicability at large structures. The developed system measures displacement by processing the images of a target plate that is attached on the measured position of a structure. To measure displacement regardless of the angle between the optical axis of the camera and the target plate, planar homography is employed to match two planes in image and world coordinate systems. To validate the performance of the present system, a laboratory test is carried out using a small 2-story shear building model. The result shows that the present system measures accurate displacement of the structure even with a camera significantly angled with the target plate.

Influence of Zero Reading on Predicting Crown Displacement of Tunnel (초기계측 시점이 터널 내공변위 예측에 미치는 영향분석)

  • Kim, Kwang-Yeom;Kim, Ho-Geun;Seo, Youg-Seok
    • Tunnel and Underground Space
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    • v.22 no.3
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    • pp.214-220
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    • 2012
  • Deformation behaviour of rock mass around an opening measured during tunnel excavation is very important in order to assess the stability of the tunnel. Unfortunately displacement measured only after the installation of displacement measuring device can be acquired, which results in inevitably excluding the pre-displacement occurred and accumulated before the displacement measuring devices are installed. So it is very important to consider the pre-displacement based on the elapsed time before zero reading after deformation behaviour started. In this study, the accuracy of total estimated displacement depending on the distance between face and measurement position is calculated by statistical non-linear fitting on measurable displacement data. Besides, the influence of the unavoidable measurement error is considered by using Monte-Carlo simulation. As a result, the faster the initial reading started and the smaller the measurement error is, the higher the accuracy of estimating total displacement is obtained.

Study on the Convergence of the NATM Tunnel Constructed in the Weathered Granite (풍화 화강암 지반에 건설된 NATM터널에서의 내공변위 연구)

  • Shin, Sang-Sik;Kim, Hak Joon;Bae, Gyu Jin
    • Tunnel and Underground Space
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    • v.25 no.6
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    • pp.515-526
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    • 2015
  • Predicting and measuring tunnel convergence is very crucial for estimating tunnel stability and economical construction of NATM tunnels. The method to estimate the tunnel convergence that occurs before and after construction is proposed based on literature reviews. The total displacement occurring related to tunnel construction is determined to be about 2.5 times that of measured displacements. The results of displacement measurements at two tunnels constructed with similar rock types are examined for the investigation of factors affecting the tunnel convergence. The average convergence of Gyungju A Tunnel is about 6.7 times bigger than that of Daejeon B Tunnel. The possible causes of the large convergence in Gyungju A Tunnel are suggested. In order to predict the convergence of tunnels, careful investigation of the geological structures in the ground surface and the influence of external conditions as well as careful face mapping of the tunnel face should be conducted.

Measurement of Dynamic Characteristics on Structure using Non-marker Vision-based Displacement Measurement System (비마커 영상기반 변위계측 시스템을 이용한 구조물의 동특성 측정)

  • Choi, Insub;Kim, JunHee
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.29 no.4
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    • pp.301-308
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    • 2016
  • In this study, a novel method referred as non-marker vision-based displacement measuring system(NVDMS) was introduced in order to measure the displacement of structure. There are two distinct differences between proposed NVDMS and existing vision-based displacement measuring system(VDMS). First, the NVDMS extracts the pixel coordinates of the structure using a feature point not a marker. Second, in the NVDMS, the scaling factor in order to convert the coordinates of a feature points from pixel value to physical value can be calculated by using the external conditions between the camera and the structure, which are distance, angle, and focal length, while the scaling factor for VDMS can be calculated by using the geometry of marker. The free vibration test using the three-stories scale model was conducted in order to analyze the reliability of the displacement data obtained from the NVDMS by comparing the reference data obtained from laser displacement sensor(LDS), and the measurement of dynamic characteristics was proceed using the displacement data. The NVDMS can accurately measure the dynamic displacement of the structure without the marker, and the high reliability of the dynamic characteristics obtained from the NVDMS are secured.

Evaluation for Lateral Movements of Bridge Abutment on Soft Ground (연약지반상 교대측방이동에 대한 판정)

  • 홍원표;송영석;조용량
    • Journal of the Korean Geotechnical Society
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    • v.17 no.4
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    • pp.269-278
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    • 2001
  • 국내 30개의 교대측방이동 사례현장에 대하여 교대기초말뚝의 사면안정효과와 교대의 실측측방변위를 고려한 사면안정해석을 실시하였다. 해석결과 사면안전율은 말뚝의 효과를 무시한 경우 1.5이상, 말뚤의 효과를 고려한 경우 1.8이상 되어야 안전함을 알 수 있다. 그리고, 교대의 실측측방변위와 사면안전율과의 상관관계로부터 교대의 허용측방변위 설계기준은 5cm보다 1.5cm로 함이 더 합리적임을 알 수 있다. 사면안정해석결과와 교대의 실측측방변위를 토대로 기존에 제안된 교대측방이동 판정기준의 국내 적용여부를 검토한다. 이를 위하여 교대의 사면안정해석결과 및 실측측방변위와 교대측방이동 관련지수와의 상관관계를 조사한다. 그 결과 실측된 교대의 측방변위와 이를 고려한 사면안전율은 교대의 측방유동지수, 측방이동판정지수 및 지반의 안정계수와 무관한 경우도 많이 존재하는 것으로 나타났다. 이는 결국 이들 경험적인 지수만으로 교대측방이동을 판정하는 것은 불충분함을 의미한다. 따라서, 교대측방이동을 판정할 경우에는 반드시 교대의 측방변위를 고려한 사면안정해석이 실시되어야 한다.

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The Relationship between Loading Velocity and Ground Heaving Characteristics (재하속도와 지반융기 특성의 상호관계)

  • Oh, Se-Wook
    • Journal of the Korean Geoenvironmental Society
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    • v.7 no.3
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    • pp.77-83
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    • 2006
  • The purpose of this study is to analyze lateral displacement behavior of clay layers in case of the banking in soft ground through model tests. Seven model tests varying with thickness of soft clay and loading velocity are performed to correlate between ground heaving and loading velocity. In case of low loading velocity, vertical settlement below loading plate and small ground heaving are obviously observed. In case of the high loading velocity, it is shown that both soil displacement at the end of a loading plate and surface heaving are large. In addition, the calculated displacements show good agreement with three cases of field measurements in clay with high moisture contents so that we can predict the range of heaving area and the amount of heaving.

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Analytical Study on Viscoelastic Damper System with Displacement-Amplification Unit (변위증폭형 점탄성 댐퍼시스템에 관한 해석적 연구)

  • Son, Young-Seon;Choi, Ki-Sun;You, Young-Chan;Kim, Keung-Hwan
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.205-206
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    • 2009
  • This study deals with the viscoelastic damper system with displacement-amplification unit (DAU) which can maximize the effectiveness of a damper system in controlling seismic response of a building by amplifying story drift induced to damper. DAUs in this study were analyzed to be able to amplify the displacement 2 to 4 times greater than the original story drift. The efficiency of each DAU was expressed by $\beta$ (DAU ratio) and examined in this analytical study.

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