• Title, Summary, Keyword: 변위

Search Result 6,090, Processing Time 0.043 seconds

Evaluation of Seismic Displacements of Quay Walls Using Newmark Sliding Block Method (Newmark 변위법을 이용한 중력식 안벽의 지진변위 산정)

  • 김성렬;장인성;정충기;김명모
    • Journal of the Korean Geotechnical Society
    • /
    • v.20 no.8
    • /
    • pp.123-133
    • /
    • 2004
  • The magnitudes of wall thrust acting on quay walls can easily vary due to the development of excess pore pressure in backfill. In this research, a new displacement model was proposed to predict the displacement of the wall considering such magnitude variations of the wall thrust. This model is based on Newmark sliding block concept. The magnitude variation of the wall thrust is modelled by varying the magnitude of yield acceleration. The parametric study was performed to analyze the effects of input parameters on the seismic displacement of the wall, and the validity of this model was verified by comparing its predicted displacements with those of Is shaking table tests.

Prediction of the Thrust Center Movement Due To Rocket Nozzle Deflection (로켓 노즐 변위에 따른 추력 중심 변화 예측)

  • Ok, Ho-Nam;Kim, In-Sun
    • Aerospace Engineering and Technology
    • /
    • v.6 no.1
    • /
    • pp.136-145
    • /
    • 2007
  • A computation was made to predict the movement of the thrust center position due to the rocket nozzle deflection. Three dimensional computations were done for the nozzle deflection angles of 0/1/3 degrees, and the oscillation of aerodynamic coefficients, not observed for the axisymmetric cases, was encountered. The position of the thrust center was found to be at -16 mm and -4 mm for the deflection angles of 1 and 3 degrees, respectively, and it can be concluded that the thrust center movement due to nozzle deflection is negligible. In addition to the computational results, the mechanism of thrust generation in a rocket engine is described with a brief mathematical derivation as it is sometimes mistaken. Also presented are some descriptions on the problem of pressure center definition for symmetric cases such as a rocket external flow problem and the nozzle deflection case.

  • PDF

A Study on DRM Model using Electronic Cash System (영상 이동변위 기반의 휴대 장치의 새로운 사용자 인터페이스)

  • Jin, Hong-Yik;Park, Sea-Nae;Sim, Dong-Gyu;NamKung, Jae-Chan
    • Journal of Korea Multimedia Society
    • /
    • v.11 no.4
    • /
    • pp.454-461
    • /
    • 2008
  • This paper is regarding a new input interface based on displacement of mobile devices having a camera. The mobile device can capture consecutive images by the camera, the displacement of the device is estimated by computing the displacement between consecutive images in real-time. The proposed system extracts feature points based on SUSAN comer detector which has low computational complexity. We generate Voronoi domain by using the two-pass algorithm to match extracted features. Finally, the displacement of a mobile device is estimated by calculating SAD values between two consecutive images. We evaluated the performance of the proposed algorithm with 1500 images. True matching accuracy of the proposed algorithm is 90% and the computation for each image is conducted in 5m sec.

  • PDF

Feasibility Study of Structural Behavior Monitoring Using GPS and Accelerometer (GPS와 가속도계를 이용한 구조물 거동모니터링의 타당성 연구)

  • Han, Jung Hun;Ryu, Sung Chan;Cho, Doo Yong;Park, Sun Kyu
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.16 no.3
    • /
    • pp.11-22
    • /
    • 2012
  • In this study, problems of RTK (Real Time Kinematic)-GPS (Global Positioning System) and an accelerometer sensor when applied to structures were experimentally identified through a comparison between results of the displacement measurement using the RTK-GPS, the accelerometer, and LVDT (Linear variable differential transformer). Integrated displacement was calculated by the improved RTK-GPS and accelerometer on the frequency of observation and positioning accuracy. This integrated displacement was also compared with that of LVDT to check the validity of application and feasibility.

Feasibility Assessment of the Photogrammetric-board for Deformation Measuring of Reinforced-soil Wall (보강토 옹벽 변위측량을 위한 사진측량용 표정판 적용 가능성 평가)

  • Lee, Hyoseong;Na, Hyunho;Park, Byung-Wook;Kim, Yong Don
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
    • /
    • v.34 no.5
    • /
    • pp.495-501
    • /
    • 2016
  • This study applied close-range digital photogrammetry to measure deformation of reinforced-soil wall as the passed time. We proposed to utilize the photogrammetric-board to determine 3D coordinates and compute exterior orientation parameters from the images without measuring control points. The displacements by the proposed method are compared with those of the Total-station. As results, measuring errors was within 5cm, and the deformation was not occurred in the 3 months. The proposed method using the photogrammetric-board therefore can be utilized to measure deformation of the reinforced-soil wall.

Examination of Allowable Displacement by Structural Analysis of IPM Bridge (토압분리형 교량의 구조해석을 통한 허용 변위량 검토)

  • Kim, Hong-Bae;Han, Heui-Soo
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.20 no.4
    • /
    • pp.534-544
    • /
    • 2019
  • Because the pile-bent of IPM Bridge is projected from the soil surface, excessive displacement of abutment can be induced. According to design guide of IPM Bridge, the shape of the bridges used in this study was applied to the maximum applicable 120.0m span, 30-degree for skew angle, and 10.0m for the protruded pile-bent height. The maximum displacement by the maximum span application condition of the IPM Bridge was calculated using this bridge model, and the safety of a horizontal displacement of the IPM Bridge was investigated based on the allowable displacement presented by Bozozuk. The maximum horizontal displacement of the IPM Bridge was calculated to be larger in the winter shrinkage condition than in the summer expansion condition, the horizontal displacements were more affected by the length of a bridge than by the skew angle. And the vertical displacement was not affected by the skew angle and length. As the span increases, the horizontal displacement increases significantly, the horizontal displacement at 120.0m span length was found to exceed the allowable displacement proposed by Bozozuk. However, the moment generated in the pile-bent did not exceed the plastic moment.

Estimation of Dynamic Displacement and Characteristics of A Simple Beam from FBG Sensor Signals (FBG센서 응답을 이용한 단순보의 동적 변위 및 동특성 추정)

  • Choi, Eun Soo;Kang, Dong Hoon;Chung, Won Seok;Kim, Hak Soo
    • Journal of Korean Society of Steel Construction
    • /
    • v.18 no.4
    • /
    • pp.503-514
    • /
    • 2006
  • FBG sensors are capable of measuring the strain of structures easily and more durably than electric resistance gauges. Thus, many researches are dedicated to the application for the response monitoring or non-destructive evaluation of structures using FBG sensors. Additionally, the measured strains at the top and bottom of a cross-section can be transformed into the curvature of the section, which can be used to calculate its vertical displacement. Hence, this study aims to measure the dynamic strain signals of a steel section simply supported beam and to estimate the dynamic displacement from the strain signals, after which the estimated displacement is com pared with the measured displacement. The dynamic characteristics (natural frequency, damping ratio and mode shape) of the beam are predicted from both the estimated and measured displacement signals, and from the strain time history of the FBG sensors. The predicted properties are compared with those of an analytical model of the beam. The estimated displacement. However, the predicted dynamic properties from both the estimated displacements and the measured strains are well-correlated with those from the measured displacement. It is therefore appreciated that the estimation of the dynamic properties of FBG sensor signals is reasonable. Especially, the strain signal of the FBG sensor was amplified at a higher-frequency region in comparison with the displacement estimation with higher-mode properties.

Comparison of Performance of Restrainers of Steel Cables and Shape Memory Alloy Bars for Multiple-Span-Simply-Supported Bridges (다경간 단순지지 교량의 강케이블 및 형상기억합금 변위제어장치의 성능 비교)

  • Choi, Eun Soo;Kim, Lee Hyeon;Park, Joo Nam;Cho, Hyo Nam
    • Journal of Korean Society of Steel Construction
    • /
    • v.19 no.6
    • /
    • pp.587-597
    • /
    • 2007
  • Steel restrainer cables for multiple frame bridges in California in the United States have been shown to be effective in preventing unseating at internal hinges during the past several earthquakes. Consequently, the steel-cable-restrainer is being tested for applications on multiple-span-simply-supported (MSSS) bridges in the mid-American region. In addition, shape memory alloy (SMA) bars in tension are being studied for the same application, multiple frame bridges, the developed seismic forces are transferred to piers through the restrainers. However, in MSSS bridges, the seismic forces are transferred to abutments by the restrainers. Therefore, the abutment' behavior should also be investigated. In this study, we assessed the seismic performance of the three types of restrainers, such as steel restrainer cables, SMA in tension, and SMA in bending for an MSSS bridge from moderate to strong ground motion, bending test of an SMA bar was conducted and its analytical model was determined for this study. Nonlinear time history analyses were conducted to assess the seismic responses of the as-built and the retrofitted bridges. All three types of restrainers reduced the hinge opening and the SMA in tension was the most effective of the three devices in preventing the unseating, all restrainers produced damage on the abutment from the pulling action of the MSSS bridge due to strong ground motions, was found that the retrofit of the abutment in the pulling action is required in the installation of restrainers in MSSS bridges.

Morphologic and positional assessment of temporomandibular joint disk in facial asymmetric patients by magnetic resonance imaging (자기 공명 영상을 이용한 안면비대칭환자의 측두하악관절원반의 형태와 위치에 관한 연구)

  • Zou, Bingshuang;Kim, Tae-Woo;Choi, Soon-Chul
    • The korean journal of orthodontics
    • /
    • v.35 no.5
    • /
    • pp.398-407
    • /
    • 2005
  • The present study was conducted to examine the morphometrics and function of the disk on both sides among patients with facial asymmetry (FA) and to elucidate plausible correlations between internal derangement (ID) and FA. The sample was composed of 10 males and 27 females with FA. The disk status of all subjects was evaluated by bilateral high resolution magnetic resonance scans in the sagittal (closed and open) and coronal (closed) planes. Five types of disk displacement were identified accordingly. The disk function was diagnosed as normal disk function, disk displacement with reduction, and disk displacement without reduction. The disk shape on sagittal MRI in closed position was classified as bi-concave, biplanar, funnel/hemiconvex, and deformed. The disk position, translation and rotation were also measured. The difference between the shifted side and non-shifted side was analyzed by statistical analysis. Approximately $70\%$ of the patients in the present study showed unilateral or bilateral ID. It was found that anterior disk displacements (ADD), especially rotational ADD, occurred more frequently in the shifted side, while normal disk position was observed mainly in the non-shifted side (p<0.01). The disk of the shifted side showed significantly deformed configuration and inferior-anterior disk position. However, the disk of the non-deviated side showed hyper-mobility during jaw opening movement. These results demonstrate that in FA patients, the disks status of the shifted side is different from that of the non-shifted side, a phenomenon that could be correlated to facial asymmetry.

A study on the relationship between initial and final convergence in NATM tunnels (NATM 터널 굴착시 초기 내공변위와 최종 내공변위의 상관관계 연구)

  • Kim, Bum-Joo;Hwang, Young-Cheol
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.10 no.3
    • /
    • pp.233-243
    • /
    • 2008
  • A tunnel behavior predicted in the investigation and design stage is often different from its actual behavior due to mainly the complexity of ground conditions. In a tunnel construction, therefore, it is necessary to ensure the stability of the tunnel by predicting the behaviors of the ground and the supports through observations and measurements, and modifying immediately excavation and reinforcing methods when necessary. To do so, it is important to be able to predict the final tunnel behavior based on the initial tunnel behavior as early as possible. In this study, the correlations were obtained between the initial and the final convergence by analyzing statistically the convergence measurement data, collected from two domestic road tunnels under construction using NATM. In order to estimate the unknown displacements, occurred during the period between the excavation and the first measurement, two methods were used - one is the method by means of regression analysis using a modified exponential function and the other the method by a simple linear regression analysis using the data measured within the distance from tunnel face equal to the tunnel diameter (D). Finally, the relationships were obtained between the initial and final convergence, including the non-measured displacements estimated from the two different methods, by performing linear regression analyses. The regression analysis results showed that there are clear linear relationships between the initial and final convegence and the difference between the two linear regression equations was not that large for when using the exponential function and the simple linear function to estimate the non-measured displacements.

  • PDF