• Journal of Platform Technology
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• v.11 no.3
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• pp.68-75
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• 2023

This paper discusses methods for increasing the germination rate of barley seeds using low direct and alternating current power below 110V. The experimental apparatus used here is a parallel plate, with the bottom surface of the plate designed to be wider than the top surface to increase the size of the electrostatic field. As a result, three different magnitudes of electrostatic fields were created on the plates: the first ranging from 400V/cm to 600V/cm, the second from 600V/cm to 900V/cm, and the third from 2200V/cm to 2400V/cm. The finite difference method was applied to analyze the electrostatic field inside the parallel plate. The plant seeds used in the experiments were barley seeds produced domestically. The average germination rate of barley seeds using the presented electrostatic field in this paper was 57%, while it was 65% when using a microwave of 2.45GHz, compared to a control group with a result of 31%. An important difference between using the electrostatic field and the 2.45GHz microwave is the dry method and wet method. When applying these two methods to practical seed germination, it is necessary to consider the advantages and disadvantages of each experimental approach and choose the appropriate method accordingly.

• Smart Structures and Systems
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• v.8 no.3
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• pp.253-274
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• 2011

In this paper, the harmonic displacement response of a damaged square plate with all-over part-through damage parallel to one edge is utilized as the input signal function in wavelet analysis. The method requires the properties of the damaged plate, i.e., no information about the original undamaged structure is required. The location of damage is identified by sudden changes in the spatial variation of transformed response. The incurred damage causes a change in the stiffness or mass of the plate. This causes a localized singularity which can be identified by a wavelet analysis of the displacement response. In this study via numerical examples shown by using harmonic response is more versatile and effective compared with the static deflection response, specially in the presence of noise. In the light of the obtained results, suggestions for future work are presented and discussed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.1
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• pp.10-17
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• 1984

The critical conditions marking the onset of thermally induced vortices over an inclined iso-thermal plate are investigated using the linear stability theory. The stability equations are simplified by estimating the orders of magnitude of respective terms. The analysis is carried out under the assumption that for the system of large Prandtl numbers temperature disturbances are initiated within the conventional thermal boundary layer of the basic flow. The stability criteria obtained from the present results agree well with those of the existing quasi-parallel flow models. In addition it is found that the critical conditions generate the heat transfer correlation in good agreement with experiments. Therefore, it is suggested that the validity of existing theoretical models will be reexamined.

• Journal of Mechanical Science and Technology
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• v.20 no.12
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• pp.2250-2264
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• 2006

In micro- and nanoflows, the Boltzmann distribution is valid only when the electric double layers (EDL's) are not overlapped and the ionic distributions establish an equilibrium state. The present study has numerically investigated unsteady two-dimensional fully-developed electroosmotic flows between two parallel flat plates in the nonoverlapped and overlapped EDL cases, without any assumption of the Boltzmann distribution. For the study, two kinds of unsteady flows are considered: one is the impulsive application of a constant electric field and the other is the application of a sinusoidally oscillating electric field. For the numerical simulations, the ionic-species and electric-field equations as well as the continuity and momentum ones are solved. Numerical simulations are successful in accurately predicting unsteady electroosmotic flows and ionic distributions. Results show that the nonoverlapped and overlapped cases are totally different in their basic characteristics. This study would contribute to further understanding unsteady electroosmotic flows in micro- and nanofluidic devices.

• Journal of Welding and Joining
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• v.21 no.4
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• pp.31-38
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• 2003

Line heating is an effective and economical process for forming flat metal plates into three-dimensional shapes for plating of ships. Because the nature of the line heating process is a transient thermal process, followed by a thermo elastic plastic stress field, predicting deformed shapes of plate is very difficult and complex problem. In this paper, neural network model o3r solving the inverse problem of metal forming is proposed. The backpropagation neural network systems for determining line-heating positions from object shape of plate are reported in this paper. Two cases of the network are constructed-the first case has 18 lines which have different positions and directions and the second case has 10 parallel heating lines. The input data are vertical displacements of plate and the output data are selected heating lines. The train sets of neural network are obtained by using an analytical solution that predicts plate deformations in line heating process. This method shows the feasibility that the neural network can be used to determine the heating-line positions in line heating process.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.771-775
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• 2006

There has been much effort to find suitable methods for structural analysis in the mid-frequency region where traditional low frequency methods have increasing uncertainties whilst statistical energy analysis is not strictly applicable. Systems consisting of relatively stiff beams coupled to flexible plates have a particularly broad mid-frequency region where the beams support only a few modes whilst the plate has a high modal density and modal overlap. A system of two parallel beams coupled to a plate is investigated based on the wave method, which is an approximate method. The wave model is extended from a single-beam-plate system, to a plate with two identical beams which is modelled using a symmetric-anti symmetric technique. Experimental results such as powers and energy ratios show the validity of the analytical wave models.

• Journal of electromagnetic engineering and science
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• v.5 no.4
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• pp.193-196
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• 2005

The DC power-bus for the PCB is loaded with metal walls on its selected sides and is characterized electromagnetically. This is a novel concept of approach to mitigate the spurious resonance and finally signal integrity problems. In particular, the peak at DC, which is always in the way to secure parallel-plates' EMC, can be completely removed by the proposed method. Through the findings of this study, the effect of metal-loading of the power-bus will be presented along with the impression that the suggested technique can tackle the headaches of signal integrity, ground bounce, EMIs.

• Korea-Australia Rheology Journal
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• v.14 no.4
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• pp.203-207
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• 2002

Particle-particle interaction is of great importance in the study of suspension rheology. In this research we have investigated the hydrodynamic interaction between two identical cylinders in viscoelastic fluids numerically as a model problem for the study of viscoelastic suspension. We confine two neutrally buoyant cylinders between two parallel plates and impose a shear flow. We determine the migration velocity of two cylinders. The result shows that cylinders move toward or away from each other depending upon the initial distance between them and that there is an equilibrium distance between two cylinders in viscoelastic fluids regardless of the initial distance. In the case of Newtonian fluid, there is no relative movement as expected. The results partly explain the chaining phenomena of spherical particles in shear flows of viscoelastic fluids.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.11
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• pp.1418-1425
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• 1999

Flow over a protruding surface is investigated using numerical simulation. We consider flow between two parallel plates with a cube mounted on one side of the channel. As the flow approaches the cube, the adverse pressure gradient produces three-dimensional boundary-layer separation, resulting In the formation of horseshoe vortices. The objective of our study is to clarify both the steady and the unsteady characteristics of the vortex system. As the Reynolds number increases, the structure of the vortices near the cube becomes complex and the number of vortices increases. The distribution of skin friction on the cube-mounted wall reflects the effect of the horseshoe vortices. All these results are consistent with the experimental findings currently available.

• Structural Engineering and Mechanics
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• v.26 no.5
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• pp.591-615
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• 2007

An improvement is introduced to solve the plane problems of linear elasticity by reciprocal theorem for orthotropic materials. This method gives an integral equation with complex kernels which will be solved numerically. An artificial boundary is defined to eliminate the singularities and also an algorithm is introduced to calculate multi-valued complex functions which belonged to the kernels of the integral equation. The chosen sample problem is a plate, having a circular or elliptical hole, stretched by the forces parallel to one of the principal directions of the material. Results are compatible with the solutions given by Lekhnitskii for an infinite plane. Five different orthotropic materials are considered. Stress distributions have been calculated inside and on the boundary. There is no boundary layer effect. For comparison, some sample problems are also solved by finite element method and to check the accuracy of the presented method, two sample problems are also solved for infinite plate.