• Structural Engineering and Mechanics
• /
• v.33 no.5
• /
• pp.621-633
• /
• 2009

In this paper we compare the solution of the one-dimensional beam model and the numerical solution of the two-dimensional linearized elasticity problem for rectangular domain of the beam-like form. We first derive the beam model starting from the two-dimensional linearized elasticity, the same way it is derived from the three-dimensional linearized elasticity. Then we present the numerical solution of the two-dimensional problem by finite element method. As expected the difference of two approximations becomes smaller as the thickness of the beam tends to zero. We then analyze the applicability of the one-dimensional model and verify the main properties of the beam modeling for thin beams.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2006.04a
• /
• pp.849-856
• /
• 2006

This paper is to examine the applicability of ordinary Kriging interpolation(OK) to the p-adaptivity of the finite element analysis that is based on variogram. In the p-refinement, the analytical domain has to be refined automatically to obtain an acceptable level of accuracy by increasing the p-level non-uniformly or selectively. In case of non-uniform p-distribution, the continuity between elements with different polynomial orders is achieved by assigning zero higher-order derivatives associated with the edge in common with the lower-order derivatives. It is demonstrated that the validity of the proposed approach by analyzing results for stress singularity problem.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2001.09a
• /
• pp.391-398
• /
• 2001

This paper presents the application method of a wavelet theory for identification of the structural dynamic properties of a bridge, which is based on the ambient vibration signal caused by the traffic loadings. The method utilizes the time-scale decomposition of the ambient vibration signal , i . e. the continuous wavelet transform using the Morlet wavelet is used to decompose the ambient vibration signal into the time-scale domain. The applicability of the proposed approach is verified through the reduced scale bridge and automobile system in the laboratory. The results of verification shows that the use of the Morlet wavelet to identify the structural dynamic properties is reasonable and practicable.

• Journal of KSNVE
• /
• v.9 no.1
• /
• pp.103-112
• /
• 1999

A new modeling and analysis technique for one-dimensional distributed parameter systems is presented. First. discretized equations of motion in Laplace domain are derived by applying discretization methods for partial differential equations of a one-dimensional structure with respect to spatial coordinate. Secondly. the z and inverse z transformations are applied to the discretized equations of motion for obtaining a dynamic matrix for a uniform element. Four different discretization methods are tested with an example. Finally, taking infinite on the number of step for a uniform element leads to an exact dynamic matrix for the uniform element. A generalized modal analysis procedure for eigenvalue analysis and modal expansion is also presented. The resulting element dynamic matrix is tested with a numerical example. Another application example is provided to demonstrate the applicability of the proposed method.

• Proceedings of the International Microelectronics And Packaging Society Conference
• /
• 2003.11a
• /
• pp.247-250
• /
• 2003

In this paper, the boundary element analysis of viscoelastic strain energy release ,ate G(t) for the cracked linear viscoelastic materials is attempted. This study proposes the G(t) equation and the calculating method of G(t) by time-domain boundary element analysis for the viscoelastic solids. The G(t) is defined as the derivative of the viscoelastic potential energy $\Pi(t)$ with respect to crack length a. Two example problems are presented to show the applicability of the proposed method to the analysis of the cracked linear viscoelastic solids. Numerical results of example problems show the accuracy and effectiveness of the proposed method.

• Journal of Environmental Health Sciences
• /
• v.38 no.6
• /
• pp.550-560
• /
• 2012

Objectives: QSAR methodology was applied to explain two different sets of acceptable daily intake (ADI) data of 74 pesticides proposed by both the USEPA and WHO in terms of setting guidelines for food and drinking water. Methods: A subset of calculated descriptors was selected from Dragon$^{(R)}$ software. QSARs were then developed utilizing a statistical technique, genetic algorithm-multiple linear regression (GA-MLR). The differences in each specific model in the prediction of the ADI of the pesticides were discussed. Results: The stepwise multiple linear regression analysis resulted in a statistically significant QSAR model with five descriptors. Resultant QSAR models were robust, showing good utility across multiple classes of pesticide compounds. The applicability domain was also defined. The proposed models were robust and satisfactory. Conclusions: The QSAR model could be a feasible and effective tool for predicting ADI and for the comparison of logADIEPA to logADIWHO. The statistical results agree with the fact that USEPA focuses on more subtle endpoints than does WHO.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.16 no.1 s.106
• /
• pp.3-11
• /
• 2006

This paper presents a new approach for hysteresis modeling of a magnetorheological (MR) fluid. The field-dependent hysteresis of MR fluid is investigated using the Preisach model. The commercial MR product (MRF-132LD, Lord Corporation) is employed. Its field-dependent shear stress is then obtained using a rheometer (MCR 300, Physica). In order to show the applicability of the Preisach model to the MR fluid, two significant properties; the minor loop property and the wiping-out. property are experimentally examined. Subsequently, the Preisach model for the MR fluid is identified using experimental first order descending (FOD) curves in discrete manner. The effectiveness of the identified hysteresis model is verified in the time domain by comparing the predicted field-dependent shear stress with the measured one. In addition, the hysteresis model proposed in this work is compared to Bingham model.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.03a
• /
• pp.146-153
• /
• 2009

One dimensional site response analysis is widely used in prediction of the ground motion that is induced by earthquake. Equivalent linear analysis is the most widely used method due to its simplicity and ease of use. However, the equivalent linear method has been known to be unreliable since it approximates the nonlinear soil behavior within the linear framework. To consider the nonlinearity of the ground at frequency domain, frequency dependent algorithms that can simulate shear strain - frequency dependency have been proposed. In this study, the results of the modified equivalent linear analysis are compared to evaluate the degree of improvement and the applicability of the modified algorithms. Results show the novel smoothed curve that is proposed by this study indicates the most stable prediction and can enhance the accuracy of the prediction.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2002.11a
• /
• pp.217-221
• /
• 2002

In this paper, we propose a new scheme of motion tracking based on fuzzy inference (FI)and wavelet transform (WT) from image sequences. First, we present a WT to segment a feature extraction of dynamic image . The coefficient matrix for 2-level DWT tent to be clustered around the location of important features in the images, such as edge discontinuities, peaks, and corners. But these features are time varying owing to the environment conditions. Second, to reduce the spatio-temporal error, We develop a fuzzy inference algorithm. Some experiments are peformed to testify the validity and applicability of the proposed system. As a result, proposed method is relatively simple compared with the traditional space domain method. It is also well suited for motion tracking under the conditions of variation of illumination.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2000.10a
• /
• pp.361-368
• /
• 2000

This paper demonstrates how nonlinear soil behavior in a soil-structure interaction system can be realistically incorporated by using a hybrid method in a nonlinear time-domain analysis. The hybrid method employs a general-purpose nonlinear finite element program coupled with a linear SSI program for the unbounded layered soil medium In order to verify the validity and applicability of the hybrid method, nonlinear earthquake response analyses are carried out for the Hualien free-field problem, in which the ground and underground accelerations were measured during several earthquake events, and for a 2-D subway station. It is found that the nonlinear earthquake responses predicted for the Hualien free-field using the hybrid method compare very well with the observed responses whereas the subway station example gives reasonable results.