• Current Optics and Photonics
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• v.2 no.6
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• pp.499-507
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• 2018

For the spatiotemporally aligned observation of photothrombosis induction and transient variations of in vivo brain stroke, we developed a novel photothrombosis inducing system compatible to a magnetic resonance imaging (MRI) system using nonmagnetic stereotaxic equipment. From the spatial point of view, the system provides a more reliable level of reproducibility of the photothrombosis in each brain. From the temporal point of view, from T1- and T2-weighted in vivo MR (magnetic resonance) images, the transient variations such as incidence, location, and size of the thrombosis are measured quantitatively. In addition, the final variation is observed in the ex vivo brain by TTC (Triphenyltetrazolium chloride) staining based on histological assay and utilized for the verification of the MR images. From the experimental result of the rat brain, the proposed system shows more reliable characteristics for transient variations of brain strokes.

• Structural Engineering and Mechanics
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• v.59 no.6
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• pp.1019-1035
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• 2016

This paper proposes a new foundation model called "Dynamic foundation model" for the dynamic analysis of plates on foundation subjected to a moving oscillator. This model includes a linear elastic spring, shear layer, viscous damping and the special effects of mass density parameters of foundation during vibration. By using finite element method and the principle of dynamic balance, the governing equation of motion of the plate travelled by the oscillator is derived and solved by the Newmark's time integration procedure. The accuracy of the algorithm is verified by comparing the numerical results with the other numerical results in the literature. Also, the effects of mass and damping ratio of system components, stiffness of suspension system, velocity of moving oscillator, and dynamic foundation parameters on dynamic responses are investigated. A very important role of these factors will be shown in the dynamic behavior of the plate.

• Structural Engineering and Mechanics
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• v.21 no.6
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• pp.699-712
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• 2005

The response of a plate-column system having five-degree-of-freedom supported by an elastic foundation and subjected to static lateral load, harmonic ground motion and earthquake motion is studied. Two Winkler foundation models are assumed: a conventional model which supports compression and tension and a tensionless model which supports compression only. The governing equations of the problem are obtained, solved numerically and the results are presented in figures to demonstrate the behavior of the system for various values of the system parameters comparatively for the conventional and the tensionless Winkler foundation models.

• Geomechanics and Engineering
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• v.34 no.6
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• pp.649-664
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• 2023

Structural inertial interaction is a representative the effect of dynamic soil-foundation-structure interaction (SFSI), which leads to a relative displacement between soil and foundation, period lengthening, and damping increasing phenomena. However, for a system with a significantly heavy foundation, the dynamic inertia of the foundation influences and interacts with the structural seismic response. The structure-to-foundation mass ratio (MR) quantifies the distribution of mass between the structure and foundation for a structure on a shallow foundation. Although both systems exhibit the same vertical factor of safety (FS_v), the MR and corresponding seismic responses attributed to the structure and foundation masses may differ. This study explored the influence of MR on the permanent deformation and seismic response of soil-foundation-structure system considering SFSI via numerical simulations. Given that numerous dimensionless parameters of SFSI described its influence on the structural seismic response, the parameters, except for MR and FS_v, were fixed for the sensitivity analysis. The results demonstrated that the foundation inertia of heavier foundations induced more settlement due to sliding behavior of heavily-loaded systems. Moreover, the structural inertia of heavier structures evidently exhibited foundation rocking behavior, which results in a more elongated natural period of the structure for lightly-loaded systems.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.120-129
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• 2000

As structure-soil interaction analysis for the seismic analysis of structures requires a nonlinear analysis of a structure-soil system considering the inelastic characteristics of soil layers nonlinear analyses of the foundation-soil system with the horizontal excitation were performed considering the nonlinear soil conditions for the nonlinear seismic analysis of structures. Stiff soil profile of SD and soft soil profile of SE specified in UBC were considered for the soil layers of a foundation and Ramberg-Osgood model was assumed for the nonlinear characteristics of soil layers. Studies on the changes of dynamci stiffnesses and damping rations of surface and embedded foundations depending on foundation size soil layer depth and piles were performed to investigate the effects of the nonlinear soil layer on the horizontal and rotational dynamic stiffnesses and damping ratios of the foundation-soil system According to the study results nonlinear prperties of a soil laryer decreeased horizontal and rotational linear stiffnesses and increased damping ratios largely Effects of foundation size soil layer depth and piles were also significant suggesting the necessity of nonlinear seismic analyses of structures.

• Journal of the Korean GEO-environmental Society
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• v.14 no.4
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• pp.59-66
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• 2013

The foundation of offshore wind energy system is generally assumed to be fixed-ended in system analysis for the convenience of calculation and, correspondingly, it might lead a conservative design. If soil-foundation interaction get involved with the analysis, the system characteristics such as natural frequency, shear force, moment and displacement are expected to differ from those of fixed-ended case. In this study, the analysis have been conducted to identify how the response of offshore wind turbine varies upon considering the foundation flexibility with soil-foundation interaction. The model taking account of the flexibility of foundation was compared with fixed-ended model at the seabed. The flexibilities of foundation were obtained by coupled spring model at the seabed and Winkler Spring Model with soil depth. As a result, the first mode of the whole system with the Winkler Spring Model was decreased relative to that with the fixed-ended model. The results showed that the effect of foundation flexibility should be considered when designing the offshore wind energy system.

• Structural Engineering and Mechanics
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• v.42 no.1
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• pp.1-12
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• 2012

In this study, Pasternak foundation model, which is a two parameter foundation model, is used to analyze the behavior of laterally loaded beams embedded in semi-infinite media. Total potential energy variation of the system is written to formulate the problem that yielded the required field equations and the boundary conditions. Shear force discontinuities are exposed within the boundary conditions by variational method and are validated by photo elastic experiments. Exact solution of the deflection of the beam is obtained. Both foundation parameters are obtained by self calibration for this particular problem and loading type in this study. It is shown that, like the first parameter k, the second foundation parameter G also depends not only on the material type but also on the geometry and the loading type of the system. On the other hand, surface deflection of the semi infinite media under singular loading is obtained and another method is proposed to determine the foundation parameters using the solution of this problem.

• Journal of Ocean Engineering and Technology
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• v.25 no.2
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• pp.47-54
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• 2011

A piled raft foundation is one of the systems used to reduce the settlement of structures. However, the general design method for a piled raft foundation system assumes that the piles only support external loads, which exclude the bearing capacity of the raft itself. In this study, an experimental model test was performed to evaluate the raft capacity for the external load on the sand. Additionally, a part of the sandy ground under the raft was replaced with a gravel mat to reinforce the piled raft foundation system and increase the bearing capacity. Then, parametric studies of the reinforced ground were performed to determine the displacement and load-sharing ratio of the piled raft foundation system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.7
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• pp.82-88
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• 2013

IEC standards do not require to limit the earthing resistance of the concrete-embedded foundation earthing electrode which is installed to a specific value. However, in Korea the value of $5{\Omega}$ and below applies to the earthing resistance for a domestic customer whose receiving voltage is 22.9kV. This paper calculates the minimum area and volume of the concrete-embedded foundation earthing electrode in order to obtain a specific value of the earthing resistance when the electrode of the building's lightning protection system and that of its power system are interconnected. It also suggested the most appropriate method of installing the foundation earthing electrode, taking the electric characteristics of concrete into account.

• Journal of Ocean Engineering and Technology
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• v.12 no.3 s.29
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• pp.19-30
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• 1998

In this paper, the dynamic analysis of a dolphin system for mooring a floating structure such as barge mounted plant is studied. The characteristics of the soil-pile system are simplified by a set of equivalent spring elements at the mudline. To evaluate the equivalent spring constants, the finite difference method is used. Since the characteristics of the soil-pile system are nonlinear in case of soft foundation, the nonlinear dynamic analysis technique is needed. The Newmark $beta$ method incorporating the modified Newton-Raphson method(initial stiffness method) is used. A numerical analysis is performed on two mooring dolphin systems on soft foundation and rock foundation. In case of the rock foundation, the characteristics are found to be nearly linear, so the linear dynamic analysis may be sufficient to consider the foundation effect. But in case of soft foundation, the non-linearity of the foundation appears to be very signigicant, so the nonlinear dynamic analysis si needed.