• Proceedings of the Korea Concrete Institute Conference
• /
• 1990.04a
• /
• pp.116-121
• /
• 1990

Baxed on the results tested by various researchers, a complete stress-strain relation of plain and confined concrete is proposed. The peak strength and the corresponding strain are calculated by using the Mohr-Coulomb theory and elastic tri-axial constitutive relation. A parametric study was conducted to assess the influence of the plain concrete strength, the degree of confinement, the shape of the section, and the tie configuration for the square section. According to this model, the behavior of concrete section is predicted, and compared with experimental data and other proposed models on circular and square sections. A good agreement between theoretical and experimental results is observed.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05a
• /
• pp.398-401
• /
• 2006

This study investigates the behaviour of Hybrid Beam with reinforced concrete encased steel center and reinforced concrete end. Two types of encased steel shape and two sections are examined in this study. Test results showed that H-Hybrid beam is stronger than Honey-comb Hybrid beam, and the behaviour of composite beam embedded steel at the elastic state is same as that of simple beam.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.06a
• /
• pp.737-742
• /
• 2000

The paper describes a theoretical study on the flexural vibration of an elastic rectangular plate with periodically nonuniform material properties. The approximate solution of the natural frequency and mode shape has been obtained using the perturbation technique for sinusoidal modulation of the flexural rigidity and mass density. It has been shown that distributed modes exist in the plate which is a two-dimensional model of the flat panel speaker.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1997.03a
• /
• pp.121-124
• /
• 1997

In the present study, a general tool surface contac search ad check algorithm is proposed. A general tool surface is described by triangular FE mesh. To check a proposed algorithm, clover cup and L-shape cup deep drawing processes are calculated. The elastic-plastic FEM using SEAM (Shear Energy Augmented Membrane) element is adapted for numerical stability.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1999.07a
• /
• pp.208-208
• /
• 1999

It is found that with increasing power, the measured electron energy distribution by Langmuir probe evolves into a Druyvesteyn-like electron energy distribution in the low-pressure regime of 1mTorr in a small inductively coupled plasma. Electron bounce resonance is introduced to explain the transition of the electron energy distribution against the rf power, The energy diffusion coefficients which determine the shape of the electron energy distribution in elastic range are calculated with and without electron bounce resonance. This electron energy distribution transition is well explained by the electron bounce resonance.

• Journal of applied mathematics & informatics
• /
• v.7 no.3
• /
• pp.895-904
• /
• 2000

The contact problem of two elastic bodies of arbitrary shape with a general kernel form, investigated from Hertz problem, is reduced to an integral equation of the second kind with Cauchy kernel. A numerical method is adapted to determine the unknown potential function between the two surfaces under certain conditions. Many cases are derived and discussed from the work.

• Structural Engineering and Mechanics
• /
• v.45 no.3
• /
• pp.355-371
• /
• 2013

Single- and multi-span orthotropic functionally graded hollow cylinders subjected to axisymmetrical bending are investigated on the basis of a unified shear deformable shell theory, in which the transverse displacement is expressed by means of a general shape function. To approach the through-thickness inhomogeneity of the hollow cylinder, a laminated model is employed. The shape function therefore shall be determined for each fictitious layer. To improve the computational efficiency, we resort to a transfer matrix method. Based on the principle of minimum potential energy, equilibrium equations are established, which are then solved analytically using the transfer matrix method for arbitrary boundary conditions. Numerical comparisons among a third-order shear deformable shell theory, an exact elastic theory and the present theory are provided for a simply supported hollow cylinder, from which the present theory turns out to be superior in stress estimation. Distributions of displacements and stresses in single- and three-span hollow cylinders with different boundary conditions are also illustrated in numerical examples.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.22 no.3
• /
• pp.680-683
• /
• 1998

In case of the infinite body containing a rigid inclusion with line crack shape, stress intensity factor is determined and the relation between stress intensity factor and stress distribution near a crack tip is developed. Also, the relation between stress intensity factor and Kolosoff stress function is developed. Finally, these results are compared with those that the crack surface is under no traction.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.12 no.4
• /
• pp.9-17
• /
• 1993

Three types of piezoelectric sensors to detect acoustic emission signals were developed and characterized. Epicentral displacement and velocity of a plate to have infinite boundary were calculated by convolution between a Green's function and a simulated source time function to show parabolic rising characteristic. The sensor calibration system set up was composed of a steel plate, a glass capillary, an indentor and a load cell indicator The transient elastic signals were detected by the sensors. The results were compared with the theoretical results and Fast Fourier Transformed. As the results, the sensor fabricated using a disk shape of a piezoelectric PZT element showed resonant characteristics. The sensors fabricated using a conical shape PZT element and a PVDF polymer film showed the wide band characteristics for particle displacement and velocity, respectively. The calculated results showed good agreements with the transient responses in the cases of the wide band sensors and it was confirmed that the simulated source time function had been properly assumed.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2001.05a
• /
• pp.102-105
• /
• 2001

In this paper, the solution of two dimensional deflection of circular wavy elastica beam was obtained for one end clamped boundary and concentrated load condition. The beam was regarded as a linear elastic material. Wavy shape was described as a combination of half-circular arc smoothly connected each other with constant curvature of all the same magnitude and alternative sign. Also load direction was taken into account. As a result, the solution was expressed in terms of a series of integral equations. While we found the exact solutions and expressed them in terms of elliptic integrals, the recursive ignition formulae about the displacement and arc length at each segment of circular section were obtained. Algorithm of determining unknown parameters was established and the profile curve of deflected beam was shown compared with initial shape.