• The Journal of Engineering Geology
• /
• v.17 no.2 s.52
• /
• pp.197-204
• /
• 2007

Tunnel deformation happens by excavation. After installation of support, tunnel is gradually stabilized over time. Effect of excavation on tunnel behavior decreases as increase of distance from face. If the time that the displacement converges by tunnel stabilization is estimated, processes after stabilization can be advanced and economic loss can be reduced. In this study, the distance of displacement convergent point from face in the tunnel constructed on sedimentary rock is estimated using control chart method. As the results of analysis using a control of chart, displacements in a sedimentary rock tunnel are converged within 100 m from each tunnel face.

• Tunnel and Underground Space
• /
• v.23 no.2
• /
• pp.120-129
• /
• 2013

It is important to measure the displacement behind and ahead of a tunnel face during construction for evaluating mechanical stability by comparing it to a displacement criteria set by tunnel designers. The 30 m long horizontal inclinometer was installed frontward from the tunnel face and the displacement occurred ahead of a tunnel face during excavation was measured by using it. Tunnel arch settlements behind tunnel face were surveyed using a settlement pins on the arch. So total settlement and longitudinal displacement curve were obtained combining settlement measured by both the horizontal inclinometer ahead of tunnel face and the settlement pins behind the tunnel face.

• Korean Journal of Optics and Photonics
• /
• v.17 no.6
• /
• pp.500-506
• /
• 2006

An optical fiber displacement sensor has the advantages of relatively simplicity, cheap, small probe size and immunity against environmental perturbation. The working principle of the sensor is based on the intensity modulation that is detection light intensity reflecting from the surface being measured. This paper presents the mathematical model of displacement measurement mechanism of this sensor type. The theoretical and experimental data are compared to verify the model in describing the realistic approach to sensor design. Finally, the analysis results show that displacement response characteristics such as sensitivity, measuring range are easily modified by principal design parameters such as magnitude of optical Power, diameter of optical fiber core and distance between transmitting fiber and receiving fiber.

• Journal of Korean Society of Steel Construction
• /
• v.10 no.1 s.34
• /
• pp.63-72
• /
• 1998

The stiffness design method is presented as a drift control model of steel structures and applied to design of space trusses subjected to stress and displacement constraints. The stiffness design method is developed by integrating the resizing techniques for an effective drift control algorithm with the strength design process according to the commonly used design specifications such as allowable stress design. In the resizing technique the amount of material to be modified depends on the member displacement participation factors and is determined by an optimization technique. Using the stiffness design method, a structural design model for steel structures is proposed and applied to two verifying examples. As demonstrated in the examples, the displacement of the structures can be effectively controlled without expensive computational cost.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.36 no.9
• /
• pp.985-996
• /
• 2012

An unsteadily propagating permeable crack in piezoelectric materials (PMs) under anti-plane shear mechanical loading and in-plane electric loading is studied. The equilibrium equations for a transiently propagating crack in a PM are developed, and the solutions on the stress and displacement fields for a permeable crack though an asymptotic analysis are obtained. The influences of piezoelectric constant, dielectric permittivity, time rate of change of the crack tip speed and time rate of change of stress intensity factor on the stress and displacement fields at the transiently propagating crack tip are explicitly clarified. By using the stress and displacements, the characteristics of the stress and displacement at a transiently propagating crack tip in a PM are discussed.

• 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.

• Journal of the Korean Geosynthetics Society
• /
• v.7 no.2
• /
• pp.41-47
• /
• 2008

This paper describes the results of model experiments in the laboratory, which were conducted to assess the behavior characteristics of geosynthetic reinforced soil walls according to different surcharge loads and reinforcement types. The model walls were built in the box having dimension, 100 cm tall, 140 cm long, and 100cm wide. Three types of geosynthetics, geonet, geogrid A and geogrid B, are used as the reinforcements. Decomposed granite soil (SM) was used as a backfill material. Seven model walls are constructed and tested. After the construction of the model wall, the LVDTs are installed to obtain the displacements of the wall face. As the results of the model tests, the maximum horizontal displacements of the model walls occurred due to uniform surcharge pressure were measured at the 0.7H from the bottom of the wall. The more the reinforcement strength increases, the more the wall displacements decrease, and also the reduction ratio of the wall displacement decrease with increasing the surcharge pressure.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.31 no.5
• /
• pp.516-521
• /
• 2011

The basilar membrane, an important functional part of the cochlea, is responsible for spectral separation of vibration signals transmitted from the stapes. In current study, scaled-up polymer membranes designed by mimicking the human basilar membrane were used for investigation of the frequency-separation characteristic. Displacement field formed on each polymer membrane was acquired by Laser Doppler scanning vibrometer and post-processed frequency-wise. The locations of the maximum displacement along the centerline were identified and collected for individual frequency range to produce the frequency-position map of individual polymer membrane. The influences of the membrane thickness and material properties on the variation of the frequency separability were discussed.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.24 no.5
• /
• pp.473-480
• /
• 2011

Recently, the resizing algorithms based on the displacement participation factors have been developed for sizing members to satisfy stiffness criteria. It is proved that this resizing algorithms made for utilizing worker's stiffness design are practical and rational due to the simplicity and convenience of the method. The resizing algorithm can be practically and effectively applied to drift design of buildings. However, the researches on the change of inelastic behavior by the resizing algorithm has been insufficient. To identify the effect on the inelastic behavior of buildings by the resizing method, this study used the reinforced concrete shear wall-frame example. Through the application of the resizing method, the weights of shear wall in the lower class and the weights of columns and beams in the upper class increased respectively. And the initial stiffness of the building increased and the ductility of the buildings had similar with that of the initial structure.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.5
• /
• pp.503-515
• /
• 2011

We developed a walking-assistance robot for walking rehabilitation and assessed the kinematic characteristics of a prototype. The walking-assistance robot is composed of hip, knee, and ankle joints, and each joint is driven by a motor with a decelerator. The equations of angular displacement while walking were derived by theoretically analyzing human locomotion, and the calculated angular displacements were then applied to the robot controller. The output angular displacement of each joint was measured and compared with its input angular displacement in walking experiments on a treadmill at various walking speeds and strides. The differences between the input and output angular displacements are 5.22% for the hip and 2.97% for the knee joints, and it has been confirmed that the walking-assistance robot works well.