• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
• /
• v.6 no.1
• /
• pp.44-50
• /
• 2003

If the accelerometers are used in measuring the response, the absolute values of the velocity and displacement are not usually obtainable because their initial values are not accounted for in the integration of the acceleration response. A new dynamic response conversion algorithm of both the time domain and the frequency domain is proposed for the problem in estimating the displacement data by defining the transformed responses. In this algorithm, the displacement response can be obtained from the measured acceleration records by integration without requiring the knowledge of the initial velocity and displacement information. The applicability of the technique is tested by an example problem using the real bridge's superstructure under several cases of moving load. In the response conversion procedure of the frequency domain, the identified response according to the frequency can be estimated by changing over the limits of integration. If the reliability of the identified responses is ensured, it is expected that the proposed method for estimating the impact factor can be useful in the bridge's dynamic test. This method can be useful in those practical cases when the direct measurement of the displacement is difficult as in the dynamic studies of huge structure.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.11a
• /
• pp.392-395
• /
• 2003

In this study was compared with result of instrumentation and numeral analysis of non-weir of concrete dam to prepare a plan for total safety estimation method such as reliability estimation of numerical analysis result, characteristics of dam behavior and etc. The results of instrument analysis of displacement and stress on N.H.W.L was similar to that of numeral analysis.

• Proceedings of the KSR Conference
• /
• 2001.10a
• /
• pp.568-577
• /
• 2001

An important and cotinuing research effort has been concentrated to estimate safety for behavior of soil nearby construction site. This construction under ground would cause the soil to deform and vibrate at any direction. This paper presents to estimation of safety for movement and reliability for vibration due to steel tube jacked under ground.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1999.10a
• /
• pp.275-282
• /
• 1999

In this study, the algorithm which can estimate displacements from the acceleration data is developed. For proving the validity of this study, the calculated displacements are compared with the measured displacements through the forced vibration tests in the laboratory. So the sampling frequency and filtering range for the estimation of the displacements are proposed. Finally, these results are applied to estimate displacements from the acceleration data obtained from the real bridge.

• Proceedings of the KSR Conference
• /
• 2005.11a
• /
• pp.418-423
• /
• 2005

In designing underground structure such as tunnels, estimating geotechnical characteristics of the ground is one of the most important and difficult tasks. In this paper, a methodology that can identify geotechnical parameters using only field-measured relative convergence displacements is presented. By using only relative convergence measurement data, inevitable errors in absolute convergence estimation can be avoided and in turn the parameter estimation process can be simplified. The methodology utilizes sensitivity relationship between static displacement measurements and geotechnical parameters. The feasibility and applicability of the proposed methodology is verified via a 3-d numerical example of a tunnel structure.

• Structural Engineering and Mechanics
• /
• v.22 no.4
• /
• pp.401-418
• /
• 2006

Solutions to the problems of structural parameter estimation from modal response using leastsquares minimization of force or displacement residuals are generally sensitive to noise in the response measurements. The sensitivity of the parameter estimates is governed by the physical characteristics of the structure and certain features of the noisy measurements. It has been shown that the regularization method can be used to reduce effects of the measurement noise on the estimation error through adding a regularization function to the parameter estimation objective function. In this paper, we adopt the regularization function as the Euclidean norm of the difference between the values of the currently estimated parameters and the a priori parameter estimates. The effect of the regularization function on the outcome of parameter estimation is determined by a regularization factor. Based on a singular value decomposition of the sensitivity matrix of the structural response, it is shown that the optimal regularization factor is obtained by using the maximum singular value of the sensitivity matrix. This selection exhibits the condition where the effect of the a priori estimates on the solutions to the parameter estimation problem is minimal. The performance of the proposed algorithm is investigated in comparison with certain algorithms selected from the literature by using a numerical example.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.8 no.6
• /
• pp.831-837
• /
• 2013

MEMS accelerometer provides a low cost alternative in retrieving the acceleration signal for motion sensing. Theoretically, displacement can be calculated by double integrate the acceleration signal. However, in practical, it could not be done in straight forward manner due to several factors that exist in the real world. This experiment focuses on the processes from practical accelerometer signal acquisition till the result of double integration for low frequency vertical motion.

• Proceedings of the KSR Conference
• /
• 2003.10b
• /
• pp.483-488
• /
• 2003

Calibration and gauge factor readjustment process made for the health monitoring system installed in the railway bridges is reviewed and some findings are explained in this study: specifically, the calibrators made for this purpose are illustrated and the regression processes of the calibration on long-term displacement using water level sensor, longitudinal displacement using LVDT sensor, instantaneous displacement using LVDT sensors and accelerometer are described in details. Based on the regression results, new gauge factors are obtained from regression equation and another verification is made by performing another calibration again with new factors. From the second calibration, it was found that the suggested regression curves and their factors are appropriate and much better results are expected. Future work will be concentrated on the long-term analysis of the measurement data and on the database structures so that the assessment of the structure such as damage detection and remaining life estimation is possible.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.2 no.3
• /
• pp.61-71
• /
• 1998

A performance-based seismic design method for reinforced concrete building structures being developed in Japan is outlined. Technical and scientific background of the performance-based design philosophy as well as recently developed seismic design guidelines are is presented, in which maximum displacement response to design earthquake motion is used as the limit-state design criteria. A method of estimating dynamic response displacement of the structures based on static nonlinear analysis is described. A theoretical estimation of nonlinear dynamic response considering the characteristics of energy input to the system is described in detail, which may be used as the standard method in the new performance-based code. A desing philosophy not only satisfying the criteria but also evaluating seismic capacity of the structures is also introduced.

• Proceedings of the KSME Conference
• /
• 2001.11a
• /
• pp.80-86
• /
• 2001

An engineering estimation equation for the crack opening displacement (COD) is proposed for a complex cracked pipe, based on the reference stress approach. To define the reference stress, a simple plastic limit load analysis for the complex cracked pipe subjected to combined bending and tension is performed considering the crack closure effect in the compressive-stressed region. Comparison with ten published test data and the results from existing method shows that the present method not only reduces non-conservatism associated with the existing method, but also provides consistent and overall satisfactory results.