• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.345.1-345
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• 2002

This paper dealt with an experimental study on the hydroelastic vibration of clamped perforated rectangular plates submerged in water. The penetration of holes in the plates had a triangular pattern with P/D (pitch to diameter) 1.750, 2.125, 2.500, 3.000 and 3.750. The natural frequencies of the perforated plates in air were obtained by the analytical method based on the relation between the reference kinetic and maximum potential energies and compared with the experimental results. (omitted)

• Journal of the Korean Society for Aviation and Aeronautics
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• v.14 no.2
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• pp.39-44
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• 2006

The unsteady vortex lattice method is used to model lead-lag in flapping motions of a rectangular flat plate wing. The results for plunging and pitching motions were compared with the limited experimental results available and other numerical methods. They show that the method is capable of simulating many of the features of complex flapping flight. The lift, thrust and propulsive efficiency of a rectangular flat plate wing have been calculated for various lead-lag motion and reduced frequency with an amplitude of flapping angle(20o). To describe a motion profile of wing tip such as elliptic, line and circle, the phase difference of flapping and lead-lag motion was changed. And the effects of the motion profile on the aerodynamic characteristics of the flapping wing are discussed by examination of their trends.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.10a
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• pp.65-72
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• 1997

This study is the bending analysis of rectangular plates with 4-sides simply supported by Finite Element Method using substructuring technique. In finite element method, as the more number of finite element, the more dimension of matrix, it is difficult to obtain accuracy solution. In this paper substructuring technique is applied to finite element method in order to reduce the dimension of matrix according to the number of finite element mesh. To validate finite element method using substructuring technique, deflections and moments of rectangular plates by that method is compared with those of references. Considering the symmetry of the plate and load, one fourth of plate is analyzed. Operating time and the error of solutions according to the number of finite element mesh and substructure are compared with each other.

• Structural Engineering and Mechanics
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• v.5 no.6
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• pp.691-703
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• 1997

This paper investigates the optimal locations of internal point supports in a symmetric crossply laminated rectangular plate for maximum fundamental frequency of vibration. The method used for solving this optimization problem involves the Rayleigh-Ritz method for the vibration analysis and the simplex method of Nelder and Mead for the iterative search of the optimum support locations. Being a continuum method, the Rayleigh-Ritz method allows easy handling of the changing point support locations during the optimization search. Rectangular plates of various boundary conditions, aspect ratios, composed of different numbers of layers, and with one, two and three internal point supports are analysed. The interesting results on the optimal locations of the point supports showed that (a) there are multiple solutions; (b) the locations are dependent on both the plate aspect ratios and the number of layers (c) the fundamental frequency may be raised significantly with appropriate positioning of the point supports.

• Solar Energy
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• v.6 no.2
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• pp.62-69
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• 1986

An analysis is made of the fully developed laminar flow and heat transfer in a parallel flat plate with heated rectangular block arrays to investigated the influence of bouyancy force. The shrouds is considered as adiabatic, while the heated block surface transmit a uniform rate of heat flux per unit axial length. The governing equations for velocity and temperature are solved by SIMPLE(Semi-Implicit Method Pressure Linked Equation) algorithm. Detailed velocity and temperature fields and overall heat transfer on wide range of Rayleigh number and various aspect ratios of heated rectangular blocks are computed. The result show that bouyancy leads to a significient enhancement in heat transfer along with a smaller increase in pressure drop, with the great enhancement found when the aspect ratio is 3.0.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.77-79
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• 1995

This paper investigates the force on a rectangular AC supercoducting coil moving above and parallel to a conducting plate of finite thickness. Expressions are developed for the levitation and drag forces on the coil a a function of speed and frequency. The levitation force are generated at all speed including stand still in a AC supercoducting coil. The levitation and drag forces on a rectangular AC supercoducting coil are compared with those on a rectangular DC supercoducting coil moving above and parallel to a conducting plate.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.416-421
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• 2002

This paper dealt with an experimental study on the hydro-elastic vibration of clamped perforated rectangular plates submerged in water. The penetration of holes in the plates had a triangular pattern with P/D (pitch to diameter) 1.750, 2.125, 2.500, 3.000 and 3.750. The natural frequencies of the perforated plates in air were obtained by the analytical method based n the relation between the reference kinetic and maximum potential energy and compared with the experimental results. Good agreement between the results was found for the natural frequencies of the perforated plates in air. It was empirically found that the natural frequencies of the perforated plate in air increase with an increase of P/D, on the other hand, the natural frequencies of the perforated plate in contact with water decrease with an increase of P/D. Additionally, the effect of the submerged depth on the natural frequency was investigated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2541-2549
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• 2002

In order to study the vibration characteristics of fluid-structure interaction problem, two rectangular plates coupled with bounded fluid were investigated. Experimental modal analyses were carried out to extract the modal parameters of the system. Additionally. finite element modal analyses performed using a commercial computer code, ANSYS. The FEM solutions were compared with the experimental solutions to verify the finite element model. As a result, the comparison between the experiment and FEM results showed excellent agreement. The transverse vibration modes, in-phase and out-of-phase, were observed alternately in the fluid-coupled system. The thickness effect of the plates on the fluid-coupled natural frequencies and mode shapes was investigated for two different cases with the identical thickness and the unequal thickness. It was found that the coupled natural frequencies increase with the thickness for the identical plates regardless of the mode phase. The experimental and the finite element analysis results showed that the out-of-phase mode shapes were deviated from the symmetrical mode shapes in the plate transverse direction fur the unequal plate thickness case.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.4
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• pp.1395-1405
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• 1996

The purpose of this experimental research is to investigate the local heat transfer characteristics in the upward free water jet impinged on a downward flat plate of uniform heat flux. The inner shape of rectangular nozzle used was sine curve type and its contraction ratio of inlet to outlet area was five. Experimental parameters considered were Reynolds number, nozzle exit-flat plate distance, and level of supplementary water. Local Nusselt number was influenced by Reynolds number, Prandtl number, supplementary water level, and distance between the nozzle exit and flat plate. Within the impingement region, the Nusselt number has a maximum value on the nozzle center axis and decreases monotonically outward from center. Outside of the impingement region, on the other hand, the Nusselt number has a secondary peak near the position where the distance from nozzle center reaches four times the nozzle width. However if nozzle exit velocity exceeds 6.2 m/s, the secondary peak appears also in the impingement region. The empirical equation for the stagnation heat transfer is a function of Prandtl, Reynolds, and axial distance from the nozzle exit. The optimum level of supplementary water to augment the heat transfer rate at stagnation point was found to be twice the nozzle width.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.1
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• pp.70-78
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• 2003

This paper dealt with an experimental study on the hydroelastic vibration of clamped perforated rectangular plates submerged in water. The penetration of holes in the plates had a triangular pattern with P/D (pitch to diameter) 1.750, 2.125, 2.500, 3.000 and 3.750. The natural frequencies of the perforated plates in air were obtained by the analytical method based on the relation between the reference kinetic and maximum potential energy and compared with the experimental results. Good agreement between the results was found for the natural frequencies of the perforated plates in air. It was empirically found that the natural frequencies of the perforated plate in air increase with an increase of P/D, on the other hand, the natural frequencies of the perforated plate in contact with water decrease with an increase of P/D. Additionally. the effect of the submerged depth on the natural frequency was investigated.