• Structural Engineering and Mechanics
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• v.22 no.6
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• pp.719-739
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• 2006

An analytical method for the free vibration of two circular plates coupled with an inviscid and compressible fluid is developed by the Rayleigh-Ritz method. The fluid is bounded by a rigid cylindrical vessel and two circular plates with an unequal thickness and diameter. It was found that the theoretical results could predict well the fluid-coupled natural frequencies with an excellent accuracy when compared with the finite element analysis results. As the fluid thickness increases or the plate thickness difference increases, an abrupt curve veering in the natural frequency loci of the neighboring modes and drastic changes in the corresponding mode shapes are observed. The mode localization frequently appears in the higher modes and in the wide gap between the plates because of a decrease in the fluid coupling owing to the fluid dispersion effect.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.4
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• pp.43-51
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• 2001

An experimental modal analysis is the process to identify structure's dynamic characteristics such as resonant frequencies, damping values and mode shapes. An experimental model was made of stainless steel in the shape of a circular cylindrical shell and installed on the test bed with jigs. For investigating vibrational characteristics of the continuous circular cylindrical shell with intermediate supports, modal testing is performed by using impact hammer, accelerometer and 8-channel FFT analyzer. The frequency response function(FRF) measurements are also made on the experimental model within the frequency range from 0 to 4kHz. Modal parameters are identified from resonant peaks in the FRF's and animated deformation patterns associated with each of the resonances are shown on a computer screen. The experimental results are compared with analytical and FEA results.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.967-972
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• 2008

This paper presents the free vibration analysis of a circular plate with a concentric square hole. The present problem deals with the numerical calculation of the natural frequencies and mode shapes of vibration of the structure by means of Independent Coordinate Coupling Method (ICCM). In this study, the boundary condition is the edge of the square hole is free and the outer circular plate is simply supported. Due to the geometric abnormality, this analysis does not permit an exact solution. Since the ICCM employs coordinate systems corresponding to each domain independently, the kinetic and potential energy expressions necessary for the Rayleigh-Ritz method can be easily obtained. Lastly, the kinematic relation is imposed. In this way, the eigenvalue problem can be easily set up. The numerical results show the efficacy of the ICCM and changes in natural frequencies and modes due to the square hole size.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.276-276
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• 2003

This paper dealt with an experimental study on the free vibration of circular-tube-beam submerged in water. A circular-tube-beam is commonly founded on the nuclear fuel assembly system in nuclear reactor. The nuclear fuel assembly susceptible to flow-induced vibration in nuclear reactor. So, the nuclear fuel assembly be designed to avoid any resonance due to the vibration during the reactor operation. In the experiment, applied boundary condition is clamped-free and the effect of water height to natural frequency and damping is studied. The experiment in air and in water has been performed. Used experimental method is impact exciting method. The natural frequencies and damping ratio according to water height is presented.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.2
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• pp.192-199
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• 2009

This paper presents the free vibration analysis of a circular plate with a concentric square hole. The boundary condition is the edge of the square hole is free and the outer circular plate is simply supported. Due to the geometric abnormality, this analysis does not permit an exact solution. The present problem deals with the numerical calculation of the natural frequencies and mode shapes of vibration of the structure by independent coordinate coupling method(ICCM). The numerical results show the efficacy of the ICCM and changes in natural frequencies and modes due to the square hole size.

• Geomechanics and Engineering
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• v.32 no.6
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• pp.553-566
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• 2023

A circular tank foundation resting on the ground and subjected to axisymmetric horizontal and vertical loads and moments is analyzed using the variational principles of mechanics. The circular foundation is assumed to behave as a Kirchhoff plate with in-plane and transverse displacements. The soil beneath the foundation is assumed to be a multi-layered continuum in which the horizontal and vertical displacements are expressed as products of separable functions. The differential equations of plate and soil displacements are obtained by minimizing the total potential energy of the plate-soil system and are solved using the finite element and finite difference methods following an iterative algorithm. Comparisons with the results of equivalent two-dimensional finite element analysis and other researchers establish the accuracy of the method.

• Geomechanics and Engineering
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• v.38 no.6
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• pp.583-591
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• 2024

To properly simulate the excavation process and evaluate the structural stability of the tunnel, rigorous large deformation analysis method is necessary. This study applies two most widely used numerical approaches capable of modelling and considering the large deformations behavior during excavation process to analyze and evaluate the structural stability of circular tunnel based on tunnel boring machine (TBM) excavation. By comparing and combining the results from two numerical approaches, the deformation of the excavated ground will be analyzed. The stability of the circular tunnel from TBM tunneling was assessed based on the maximum deformation occurred during the excavation process. From the numerical computation it was concluded that although the range of the damage on the ground done during excavation was found to be larger under hard rock condition, maximum deformation within the circular tunnel structure was larger under weak ground conditions and deeper tunnel depths.

• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3411-3420
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• 2011

Kinetic and structural studies have been carried out on the effects of meso-tetrakis(4-sulfonatophenyl)-porphyrin ($H_2TPPS_4$) as an anionic and meso-tetrakis(3-N-methyl-pyridyl)porphyrin ($H_2TMPYP$) as a cationic porphyrin with adenosine deaminase (ADA) in 25 mM citrate/phosphate buffer, pH = 4-8, at $37^{\circ}C$ using UVvis spectrophotometry, circular dichroism (CD), fluorescence spectrophotometry as well as molecular dynamics (MD) and molecular docking. Kinetic results showed that the two porphyrins are non-competitive inhibitors. Increasing pH, increases $K_I$ and cationic porphyrin has a higher $K_I$ and lower binding constant ($K_b$) at all pH ranges. Analyzing the secondary structure revealed that both ligands decrease the secondary structure and that the anionic porphyrin is more effective.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.1
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• pp.60-72
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• 1994

The effect of free stream tubulence on the coherent structure in the near wake of a circular cylinder was investigated by a conditional sampling technique. The measurements were made from C.T.A. with hot wire I-probe and a Split-film sensor. Contours of phase-averaged velocity and vorticities were presented and discussed. It was found that the value of the vortex strength increased with increasing free stream turbulence which can enhance the roll-up of the shear layer.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.2
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• pp.512-518
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• 1994

An experimental study is made on turbulent diffusion flames stabilized by a circular cylinder in a divergence flow. In this paper, stabilization characteristics and flame structure are examined by varying the divergence angle of duct and position of a circular cylinder. The fuel used is a commercial grade gaseous propane injected by two slit of rod. It is found that the positive pressure gradient greatly influences the eddy structure behind the rod. and that two different kinds of combustion patterns exist at the blowoff limit depending on the divergent angle of duct. They are distinguished by their wake structures: one associated with Karman vortex shedding, the other without it. Also, the blowoff velocity in the former is found to be higher than in the later.