• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.15 no.4 s.97
• /
• pp.388-394
• /
• 2005

This paper has the object of investigating natural frequencies of tapered thick plate on Pasternak foundation by means of finite element method and providing kinetic design data for mat of building structures. Vibration analysis for tapered thick plate subjected to in-plane stress is presented in this paper. Finite element analysis of rectangular plate is done by use of rectangular finite element with 8-nodes. Analysis conditions of tapered thick plate are as follows each. The ratio of in-plane stress to critical load is varied with $0.2\sigma_{cr}$, $0.4\sigma_{cr}$, $0.6\sigma_{cr}$. The Winkler parameter is 0, 10, 100, 1000, the shear foundation parameter is 0, 10 and the taper ratio is 0.0, 0.2, 0.4, 0.6, 0.8.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.11a
• /
• pp.907-910
• /
• 2005

This paper has the object of investigating natural frequencies of tapered thick plate, tapered ratio, thick plate's opening size by means of finite element method and providing kinetic design data for mat of building structures. Free vibration analysis that tapered thick plate in this paper. Finite element analysis of rectangular plate is done by use of rectangular finite element with 8-nodes. In order to analysis plate which is varioued of plate thickness. the thickness is varied with 5, 10, 15, 20 and the tapered ratio is applied as 0.0, 0.25, 0.5, 0.75, 1.0 respectively. This paper is analyzed varying thickness by taper ratio.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.4 no.1
• /
• pp.93-101
• /
• 1984

New formulas to determine the critical elastic buckling load of long tapered columns are given. This study is restricted to solid round or rectangular columns with fixed-free ends as often used in highway design. The exact solution of the differential equation of the deflection curve is expressed in terms of Bessel Function and the solution is numerically evaluated using Bisection method by computer. In the F.E.M analysis of columns under their own weight, the stability problem can be resulted in a eigen value problem of conservative system. Approximate solution by the F.E.M is evaluted numerically using Jacobi method and compared with exact solution of the prismatic column to increase the precision. In addition, critical buckling load of the tapered column for every shape factor and ratio of cross-sectional change (Diameter of bottom end/Diameter of upper end) was converted into a comparable expression to critical buckling load of the prismatic column.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.11a
• /
• pp.819-822
• /
• 2006

This paper has the objects of deciding dynamic instability regions of thick plates on inhomogeneous Pasternak foundation by finite element method and providing kinematic design data for mats and slabs of building structures. In this paper, dynamic stability analysis of tapered opening thick plate is done by use of Serendipity finite element with 8 nodes considering shearing strain of plate. To verify this finite element method, buckling stress and natural frequencies of thick pate with or without in-plane stress are compared with existing solutions. The results are as follow that this finite element solutions with $4{\times}4$ meshes are shown the error of maximum 0.56% about existing solutions, and the larger foundation parameters, the farther dynamic instability regions are from vertical axis of graph presented relation of ${\beta}\;and\;\overline{\omega}/\omega$.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.21 no.8
• /
• pp.698-707
• /
• 2011

This paper is to analyze the stability of the thick plate on inhomogeneous Pasternak foundation, with linearly varying thickness and concentrated mass by finite element method. To verify this finite element method, the results of natural frequencies and buckling stresses by the proposed method are compared with the existing solutions. The dynamic instability regions are decided by the dynamic stability analysis of the thick plate on inhomogeneous Pasternak foundation, with linearly varying thickness and concentrated mass. The non-dimensional Winkler foundation parameter is applied as 100, 1000 and non-dimensional shear foundation parameter is applied as 5. The tapered ratios are applied as 0.25 and 1.0, the ratios of concentrated mass to plate mass as 0.25 and 1.0, and the ratio of in-plane force to critical load as 0.4. As the result of numerical analysis of the thick plate on inhomogeneous Pasternak foundation for $u{\times}v=300cm{\times}300cm$ and $a{\times}b=600cm{\times}600cm$, instability areas of the thick plate which has the larger rigidity of inner area are farther from ${\beta}$-axis and narrower than those which has the larger rigidity of outer area.

• Journal of Korea Water Resources Association
• /
• v.40 no.11
• /
• pp.899-908
• /
• 2007

In this study, wave reflection due to depression of seabed is calculated by using eigenfunction expansion method. The proper numbers of steps and evanescent modes needed for analysis are suggested by applying the eigenfunction expansion method to bottom topography of which slope or curvature varies. While satisfying shallow or intermediate water depth condition, the optimal figure of depression of seabed is obtained by calculating reflection coefficient for various depressions of seabed. The reflection coefficient with distance between the depression of seabeds is then calculated after arraying the optimal geometry in two and three rows.

• Journal of Bio-Environment Control
• /
• v.8 no.4
• /
• pp.250-256
• /
• 1999

A wrapped fruit-vegetable can restrain from evaporating its water, help to be supplied with a little fresh air, prevent from injuring and damaging during transporting to other positions. Therefore, this study was carried out to develop an automatic wrapping system specifically tailored to pack up from one to four numbers of long type fruit-vegetable in wrap foil. Performance tests of the system were conducted by using three different kinds of fruit-vegetable (cucumber, eggplant, Pumpkin) to determine the success wrapping rate. Each fruit-vegetable is divided into two grades such as A grade and B grade. B grade is more bended curve than A grade. The success wrapping rate of eggplant was 100% regardless of the grade and the number of fruit-vegetable. and also that of cucumber was 100% all but packing 4 numbers of B grade. However, that of pumpkin was 45%, As the number and the bended degree of pumpkin was increased, the success wrapping rate of pumpkin was decreased, because the surface area or the bended degree were increased.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.175-176
• /
• 2010

Current Bridge Specification for Highway Bridges adopts a simplified method to determine sectional forces of abutment wing by diving its area into four sections. This simplified method was developed when numerical analysis was not mature and computer resources were expensive. It has been criticized that the simplified method produces conservative results. This study evaluates the problem of current design practice to improve the design guideline for abutment wing.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.18 no.12
• /
• pp.1935-1944
• /
• 1993

We calculate the optimum refractive index and thickness for a single layer antireflection coating as a function of active layer thickness of a laser diode using three different simplified numerical methods. The difference of the results using three methods comes from that of the effective refractive index of a laser used in three methods. We compare three simplified methods to an exact method to check the validity of the simplified methods. We conclude that the simplified method, choosing the effective index of a laser diode as a function of incidence angle of each plane wave composing of a guided mode agree well to an exact method for both TE and TM modes and the cases of strongly and weakly guiding.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.8 no.4
• /
• pp.55-66
• /
• 2004

In this paper a method for finding solutions of acoustic, vortex and entropy wave equations in a cylindrical tube with variable section area was suggested under the consideration of that the high frequency instability in a rocket engine combustion chamber is an acoustic phenomena, which Is coupled with combustion reaction. and that a combustion chamber and exhaust nozzle are usually shaped cylindrically As a consequence of that some method. which enable the mathematical analysis of the influence of entropy and vortex waves to acoustic wave. was suggested. According to the method reflection coefficients of acoustic wave on a supercritical nozzle was numerically calculated, through which it was presented that entropy or vortex waves can strengthen or weaken the reflection rate of acoustic wave.