• Title/Summary/Keyword: Displacement

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Development of an Algorithm for Detecting Angular Bisplacement with High Accuracy Based on the Dual-Encoder (이중 증분 엔코더에 기초한 초정밀 회전각도 변위 검출 알고리즘 개발)

  • Lee, Se-Han
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.8
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    • pp.29-36
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    • 2008
  • An optical rotary encoder is easy to implement for automation system applications. In particular, the output of the encoder has a digital form pulse, which is also easy to be connected to a popular digital controller. By using an incremental encoder and a counting device, it is easy to measure angular displacement, as the number of the output pulses is proportional to the rotational displacement. This method can only detect the angular placement once a pulse signal comes out of the encoder. The angular displacement detection period is strongly subject to the change of the angular displacement in case of ultimate low velocity range. They have ultimate long detection period or cannot even detect angular displacement at near zero velocity. This paper proposes an algorithm for detecting angular displacement by using a dual encoder system with two encoders of normal resolution. The angular displacement detecting algorithm is able to keep detection period moderately at near zero velocity and even detect constant angular displacement within nominal period. It is useful for motion control applications in case of changing rotational direction at which there occurs zero velocity. In this paper, various experimental results are shown for the angular displacement detection algorithm.

Deformation Analysis of Excavated Behind Ground by The Artificial Displacement Method (II) - Numerical Analysis and Application - (강제변위법을 이용한 굴착배면지반의 변형해석(II) - 수치해석 및 적용성 -)

  • Yun, Jung-Mann
    • Journal of the Korean Geosynthetics Society
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    • v.7 no.3
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    • pp.31-40
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    • 2008
  • The deformation behavior of the excavated behind ground due to the displacement shape of retention walls is predicted by numerical analysis, which can be performed using the artificial displacement method with elasto-plastic constitutive model. The displacement shape of the behind ground around the retention wall is similar to the displacement shape of the retention wall. However, far from the retention wall, it changes to the displacement shape of cantilever. The deformation (the settlement, the lateral movement) of the excavated behind ground can be decreased by restraining the upper displacement of the retention wall. The displacement shape of the retention wall due to excavation affects on the plastic failure zone and decreasing zone of stability of the excavated behind ground.

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Estimation of Displacement Responses from the Measured Dynamic Strain Signals Using Mode Decomposition Technique (모드분해기법을 이용한 동적 변형률신호로부터 변위응답추정)

  • Kim, Sung-Wan;Chang, Sung-Jin;Kim, Nam-Sik
    • Proceedings of the KSR Conference
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    • pp.109-117
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    • 2008
  • In this study, a method predicting the displacement responseof structures from the measured dynamic strain signal is proposed by using a mode decomposition technique. Dynamic loadings including wind and seismic loadings could be exerted to the bridge. In order to examine the bridge stability against these dynamic loadings, the prediction of displacement response is very important to evaluate bridge stability. Because it may be not easy for the displacement response to be acquired directly on site, an indirect method to predict the displacement response is needed. Thus, as an alternative for predicting the displacement response indirectly, the conversion of the measured strain signal into the displacement response is suggested, while the measured strain signal can be obtained using fiber optic Bragg-grating (FBG) sensors. To overcome such a problem, a mode decomposition technique was used in this study. The measured strain signal is decomposed into each modal component by using the empirical mode decomposition(EMD) as one of mode decomposition techniques. Then, the decomposed strain signals on each modal component are transformed into the modal displacement components. And the corresponding mode shapes can be also estimated by using the proper orthogonal decomposition(POD) from the measured strain signal. Thus, total displacement response could be predicted from combining the modal displacement components.

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CHANGE OF JOINT SPACE ACCORDING TO SIDEWAYS DISC DISPLACEMENT OF TMJ (악관절원판의 측방변위에 따른 관절간극의 변화)

  • Kim, Joon-Bae;Lee, Doo-Hee;Kim, Hyung-Soo;Oh, Soon-Ho
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • v.27 no.4
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    • pp.337-343
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    • 2001
  • Objective. Disc displacement may affect the joint space narrowing between condyle head and glenoid fossa. This study was designed to evaluate the correlation between the joint space change and the directions of disc displacement. Study Design. Two hundreds temporomandibular joints MR images of TMD patients (170 joints) and asymptomatic volunteers (30 joints) were evaluated for this purpose. Anterior disc displacement was divided into 3 stages (normal, little to mild, and moderate to severe displacement) based on sagittal images. And sideways displacement was classified as 3 categories (center, medial and lateral displacement) based on coronal images, then joint spaces were measured at medial, central and lateral parts of condyle head on coronal MR images, respectively. The joint spaces of 7 groups divided according to the severity and the direction of disc displacement were compared. Results. The reduction of the joint space was affected by sideways disc displacement at the opposite side of the condyle head, except the cases accompanied with severe anteriorly and laterally displaced disc. Conclusion. The sideways disc displacement affected on the opposite side temporomandibular joint space width.

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Study on Evaluating Displacement Tolerance of Sky-bridge in Tall Buildings (고층 스카이브리지의 변위 허용치 산정에 대한 연구)

  • Kim, Yun Gon
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.36 no.4
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    • pp.135-142
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    • 2020
  • The new method for evaluating the displacement tolerance of sky-bridges with pin-roller type supports was proposed considering both return period of phase difference between connected buildings and geometrical characteristics of skybridge. Because displacement tolerance is relative value, which is most affected by the phase difference of the connected buildings, the dynamic response of these building with time history analysis should be evaluated. However, the initial phase could not be specified, so the result of displacement tolerance would be varied with respect to initial value. Thus, the tolerance can be reasonably evaluated SRSS calculation with design displacements based on statistical approach and of each building. In addition, the geometrical characteristics of sky-bridge should be considered because the transverse displacement of sky-bridge span causes the shear deformation of the bridge and longitudinal displacement tolerance cannot release the shear deformation. Therefore, the some pin-end support in sky-bridge should have longitudinal displacement tolerance to accommodate the shear deformation. By resolving this shear deformation, it is possible not only to accommodate transverse displacement, but also to avoid the complicated joint details such as both pot bearing and guided supports with shear key.

An Analysis on Volumetric Displacement of Hydraulic Gerotor Motor (제로터 유압 모터의 용량에 관한 연구)

  • Kim, D.M.;Ham, Y.B.;Kim, S.D.
    • 유공압시스템학회:학술대회논문집
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    • pp.39-43
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    • 2010
  • It is hard and complex to analytically derive a volumetric displacement formula of a gerotor hydraulic motor because geometric shape of its rotors is complicate. An analytical method about the volumetric displacement is proposed in this work, which is relatively easy and based upon two physical concepts. The first one is energy conservation between hydraulic input energy of the motor and mechanical output energy. The second concept is torque equilibrium with respect to inner and outer rotors. The proposed formula about the volumetric displacement is verified by comparing an analytical displacement and a numerical displacement for an example specification of the motor. The numerical displacement is calculated through a kind of CAD technology. The analytical formula can be utilized in analysis and design of hydraulic gerotor motors.

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A RADIOGRAPHIC STUDY ON THE CONDYLAR DISPLACEMENT FROM CENTRIC RELATION TO CENTRIC OCCLUSION (중심위에서 중심교합으로 전위될 때의 과두의 변위에 관한 방사선학적 연구)

  • Rhyee In Suk;Ahn Hyung Kyu
    • Journal of Korean Academy of Oral and Maxillofacial Radiology
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    • v.12 no.1
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    • pp.15-20
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    • 1982
  • The purpose of this study was to investigate the normal range of condylar displacement of normal adults. The author has observed two roentgenographic images of condylar head taken by transcranial projection. Two roentgenographic images are centric occlusion and centric relation. The results were obtained as follow: 1. Total subjects are 72 condyles. The condylar displacement from centric relation to centric occlusion was shown in 65 condyles (90%) anteriorly. 59 condyles (82%) inferiorly. Two condyles (3%) showed neither anterior displacement nor inferior displacement. 2. The average displacement of right condyles was 0.54±0.06㎜ anteriorly, 0.34±0.05㎜ inferiorly. The average displacement of left condyles was 0.74±0.09㎜ anteriorly, 0.45±0.05㎜ inferiorly. 3. The subjects of synmetrical displacement are 7 cases (20%) anteriorly, 2 cases (6%) inferiorly.

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Disturbance Observer-Based Hybrid Control of Displacement and Force in a Medical Tele-Analyzer

  • Suebsomran Anan;Parnichkun Manukid
    • International Journal of Control, Automation, and Systems
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    • v.3 no.1
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    • pp.70-78
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    • 2005
  • This paper presents hybrid control of displacement and force in a Medical Tele-Analyzer by disturbance observer-based controller which is robust to internal and external disturbances; model uncertainty, load, and friction for instances. The developed Medical Tele-Analyzer consists of 2 subsystems; doctor-side subsystem and patient-side subsystem. In the doctor side subsystem, an array of displacement sensor is equipped to detect movement of doctor's hand and fingers. The detected information is transmitted to the patient side to be used in medical analysis. On the other hand, the patient-side subsystem consists of an array of displacement actuators, which is used to follow displacement of doctor's hand and fingers. An array of force sensors is used to detect forces between patient and the equipment. Since displacement control in patient side is coupled with force control in doctor side and vice-versa, design of the controller has to take into account this coupling. Not only using in medical tele-analysis, the proposed system can also be used in any tele-displacement-force controls of industrial processes.

A Basic Study of Displacement Measurement of Magnetic Bearing System Using Hall Effect Sensor (자기베어링 시스템에서의 변위측정을 위한 홀 효과 센서의 기초 연구)

  • Yang, J.H.;Jeong, G.G.;Jeong, H.H.;Son, S.K.
    • Journal of Power System Engineering
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    • v.11 no.2
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    • pp.72-76
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    • 2007
  • Since the magnetic bearing system has unstability inherently it is necessary to measure the displacement for stable operation. Normally the displacement measurement is implemented by using sensors. The sensor for the displacement measurement is selected by precision, installation space, effect of magnetic field and response speed. And the cost of displacement measurement sensor also is considered. At the cost the hall effect sensor has a large advantage comparing with the others. Therefore this study concern about the basis experimental test for the displacement measurement of the magnetic bearing system that uses the hall effect sensor coupled with a tiny permanent magnet. The experimental results confirm the validity and practicability for this displacement measurement sensor.

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The Measurement Method of Lateral Displacement in Bridge Abutment. (교량구조물의 측방이동 측정방법에 관한 연구)

  • 장용채
    • Journal of Korean Port Research
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    • v.14 no.1
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    • pp.115-124
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    • 2000
  • This study is a suggest a measurement method of lateral displacement, which can be used to judge the stability of bridge abutment on soil undergoing lateral movement. The abutment of bridge on soft foundation makes lateral movement due to the settlement of back fill and lateral flow. To measure the displacement of such a abutment, there are a lot of indirect method for measurement such as survey of leveling or inclinometer gauge around the abutment. But all of them are not sufficient to confirm the ground behavior and measure the exact lateral behavior of structure. As making the structure and pile cooperatively by measuring the movement of lateral displacement, for measuring the abutment displacement precisely by using the inclinometer. In this work, we try to suggest efficient measuring method of abutment displacement and its application.

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