• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.04a
• /
• pp.797-798
• /
• 2011

• Proceedings of the Korean Geotechical Society Conference
• /
• 1994.03a
• /
• pp.43-58
• /
• 1994

In this reaserch, the comparison between numerical results and field measurments including settlement, heaving and lateral displacement, in the interchange construction works on soft ground. Sand drain was performed for the improvement of the site and steel pipe piles driven for the pier foundation of interchange. The steel pipe piles were replaced to the equivalent steel sheet pile wall. Biot's equation was coupled with elasto-viscoplastic model for the multi-purpose program of soft foundation. Finally countemeasures for future possible lateral displacement and settlement were exmanined.

• International Journal of Safety
• /
• v.6 no.1
• /
• pp.22-25
• /
• 2007

Damping out high frequency low amplitude structural vibrations using PZT bimorph is presented. Static and Dynamic analyses of the piezoelectric bimorph bender were performed. Three layer piezoelectric actuators were modeled with SOLID5 coupled-field elements using ANSYS. Static deflection and modal analyses of the piezoelectric bimorph bender are presented. Proper tuning of the values of the resistor and inductor in the shunt circuit is required for maximum vibration suppression.

• Coupled systems mechanics
• /
• v.1 no.4
• /
• pp.361-379
• /
• 2012

This paper presents a fully coupled three-dimensional solver for the analysis of interaction between pulsatile flow and large deformation structure. A partitioned time marching algorithm is employed for the solution of the time dependent coupled discretised problem, enabling the use of highly developed, robust and well-tested solvers for each field. Conservative transfer of information at the fluid-structure interface is combined with an effective multi-predict-correct iterative scheme to enable implicit coupling of the interacting fields at each time increment. The three-dimensional unsteady incompressible fluid is solved using a powerful implicit time stepping technique and an ALE formulation for moving boundaries with second-order time accurate is used. A full spectrum of total variational diminishing (TVD) schemes in unstructured grids is allowed implementation for the advection terms and finite element shape functions are used to evaluate the solution and its variation within mesh elements. A finite element dynamic analysis of the highly deformable structure is carried out with a numerical strategy combining the implicit Newmark time integration algorithm with a Newton-Raphson second-order optimisation method. The proposed model is used to predict the wave flow fields of a particular flow-induced vibrational phenomenon, and comparison of the numerical results with available experimental data validates the methodology and assesses its accuracy. Another test case about three-dimensional biomedical model with pulsatile inflow is presented to benchmark the algorithm and to demonstrate the potential applications of this method.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.6
• /
• pp.61-73
• /
• 2004

The coefficient of permeability of natural clay shows a nonlinear property which is related to various stress level of soils, and this nonlinear property has effect on the period of consolidation and the property of deformation in clay soils under loading. Thus, in this paper the numerical analysis was conducted by FEM-using coupled theory which incorporated Biot's consolidation theory into modified Cam-clay model- to consider the effects of nonlinear permeability on the behavior of clay soils under loading. The result of this paper showed that nonlinear permeability had different effects on the deformation and excess pore water pressure in clay soils according to the change of ratios of coefficients of permeability which was presented a degree of nonlinear property, and average coefficients of permeability of soils. Therefore, it was concluded that nonlinear permeability should be considered according to both the change of ratios of coefficients of permeability and average coefficients of permeability to conduct more simultaneous analyses to field conditions.

• Tunnel and Underground Space
• /
• v.5 no.3
• /
• pp.205-213
• /
• 1995

In order to construct underground structural systems safely and economically, exact identification of the system parameters and accurate analysis of the system behaviors are required. Therefore, necessity of back analysis which is able to identify material properties of underground structural systems is increased. In this study a back analysis program which can identify the system parameters is developed using the direct method to be combined with the forward analysis program. Results of the back analysis program show good agreement with that of Gens et al. Sensitivity of the accuracy and convergency of the back analysis program on the number of measuring points is investigated. Comparison between the results of the back analysis with measurement data and the obtained material properties from the field tests shows good agreement for the real construction site.

• Geomechanics and Engineering
• /
• v.21 no.5
• /
• pp.489-501
• /
• 2020

This paper conducts a complicated coupled effective stress analysis of X-section-in-place concrete (XCC) pile installation and consolidation processes using the dual-stage Eulerian-Lagrangian (DSEL) technique incorporating the modified Cam-clay model. The numerical model is verified by centrifuge data and field test results. The main objective of this study is to investigate the shape effect of XCC pile cross-section on radial total stress, excess pore pressure and time-dependent strength. The discrepancies of the penetration mechanism and set-up effects on pile shaft resistance between the XCC pile and circular pile are discussed. Particular attention is placed on the time-dependent strength around the XCC pile shaft. The results show that soil strength improved more significantly close to the flat side compared with the concave side. Additionally, the computed ultimate shaft resistance of XCC pile incorporating set-up effects is 1.45 times that of the circular pile. The present findings are likely helpful in facilitating the incorporation of set-up effects into XCC pile design practices.

• Geomechanics and Engineering
• /
• v.31 no.2
• /
• pp.209-222
• /
• 2022

Finite element analyses using coupled Eulerian-Lagrangian technique are performed to investigate the effect of soil conditions on plugging of open-ended piles in sands. Results from numerical simulations are compared against the data from field load tests on three open-ended piles and show very good agreement. A parametric study focusing on determination of the coefficient of lateral earth pressure (K) in soil plug after pile driving are then performed for various soil densities, end-bearing conditions, and layering conditions. Results from the parametric study suggest that the K value in the soil plug - and hence the degree of soil plugging - increases with increasing soil densities. The analysis results further show that the K value within the soil plug can reach about 63 to 71% of the coefficient of passive earth pressure after pile driving. For layered soil profiles, the greater K values are achieved after pile driving when the denser soil layer is present near the pile base regardless of number of soil layers. This study provides comprehensive numerical and experimental data that can be used to develop advanced theory for analysis and design of open-ended pipe piles, especially for estimation of inner shaft resistance after pile driving.

• Mass Spectrometry Letters
• /
• v.6 no.4
• /
• pp.85-90
• /
• 2015

This article reviews recent analytical techniques using inductively coupled plasma-mass spectrometry (ICP-MS) immunoassay for clinical and bio analysis. We classified the techniques into two categories, direct and indirect analysis, which depend upon a guideline of whether tagging materials are used or not. Direct analysis is well known, and generally used in conjunction with various other techniques, such as laser ablation, chromatographic separations, etc. Recently, indirect analysis using tagging elements has intensively been discussed because of its importance in future applications to bio and clinical analysis, including environmental and food industries. The method has shown advantages of multiplex detection, excellent sensitivity, and short analysis time owing to signal amplification and magnetic separation. Now, it expands the application field from small biomolecules to large cells.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.6 no.3
• /
• pp.562-577
• /
• 2014

A reliable steady/transient hydro-elastic analysis is developed for flexible (composite) marine propeller blade design which deforms according to its environmental load (ship speed, revolution speed, wake distribution, etc.) Hydro-elastic analysis based on CFD and FEM has been widely used in the engineering field because of its accurate results however it takes large computation time to apply early propeller design stage. Therefore the analysis based on a boundary element method-Finite Element Method (BEM-FEM) Fluid-Structure Interaction (FSI) is introduced for computational efficiency and accuracy. The steady FSI analysis, and its application to reverse engineering, is designed for use regarding optimum geometry and ply stack design. A time domain two-way coupled transient FSI analysis is developed by considering the hydrodynamic damping ffects of added mass due to fluid around the propeller blade. The analysis makes possible to evaluate blade strength and also enable to do risk assessment by estimating the change in performance and the deformation depending on blade position in the ship's wake. To validate this hydro-elastic analysis methodology, published model test results of P5479 and P5475 are applied to verify the steady and the transient FSI analysis, respectively. As the results, the proposed steady and unsteady analysis methodology gives sufficient accuracy to apply flexible marine propeller design.