• Journal of Power System Engineering
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• v.12 no.2
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• pp.35-40
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• 2008

This paper deals with the free vibrations of conical shells with linearly variable thickness by the transfer influence coefficient method. The classical thin shell theory based upon the Flugge theory is assumed and the governing equations of a conical shell are written as a coupled set of first order matrix differential equations using the transfer matrix. The Runge-Kutta-Gill integration method is used to solve the governing differential equation. The natural frequencies and corresponding mode shapes are calculated numerically for the conical shells with linearly variable thickness and various boundary conditions at the edges. The present method is applied to conical shells with linearly varying thickness, and the effects of the semi-vertex angle, the number of circumferential waves and thickness ratio on vibration are studied.

• Asian-Australasian Journal of Animal Sciences
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• v.6 no.3
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• pp.433-440
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• 1993

Means and standard errors of 285 Taiwan's local chicken and 429 Single Comb White Leghorn pullets at 35 wk of age were: egg weight (g) $48.3{\pm}0.3$, $54.6{\pm}0.3$, shell index $73.39{\pm}0.26$, $73.20{\pm}0.18$, shell color $15.23{\pm}0.40$, $0.88{\pm}0.27$, shell whiteness $72.61{\pm}0.57$, $90.00{\pm}0.35$, shell strength ($kg/cm^2$) $3.77{\pm}0.07$, $3.35{\pm}0.05$, shell thickness (mm) $0.38{\pm}0.003$, $0.38{\pm}0.002$, Haugh units $85.26{\pm}0.50$, $91.81{\pm}0.38$ and yolk percent (%) $30.17{\pm}0.18$, $27.32{\pm}0.16$ respectively. Theestimated heritabiliities of Taiwan's local chicken based on sire and dam components of variance were as follows: egg weight 0.20, shell index 0.1, shell color 0.87, shell whiteness 0.79, shell strength 0.37, shell thickness 0.14, Haugh units 0.24 and yolk percent 0.16. Genetic correlations based on sire and dam components of variance and covariance were also estimated. Generically, the shell index was positively correlated with egg weight, shell strength and yolk percent, and egg weight was negatively correlated with shell thickness, Haugh unit and yolk percent.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.2
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• pp.68-77
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• 2003

Shell structure are widely used in a variety of engineering application and mathematical solution of shell structures are available only for a few special cases. The solution of shell structure is more complicated when it has such condition as winker foundation, variable thickness and other problem. In this paper, a simple finite element method is presented for the analysis of axisymmetric several types of shell structure subjected to axisymmetric loads and having uniform and varying wall thickness on elastic foundation. The method is based on the analogy with a beam on elastic foundation (BEF), foundation stiffness matrix where the foundation modulus and beam flexural rigidity are replaced by appropriate parameters pertaining to the shell under considerations. The technique is attractive for implementation on a numerical solution by means of a computer program coded in FORTRAN language with a few elements. To demonstrate this fact, it gives good results which compare well with SAP2000.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.728-732
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• 2004

In the FE analysis of sheet metal forming, efficient results can be obtained by using shell elements rather than using solid elements. However, shell elements have some limitations to describe three-dimensional material laws. In the recent years, solid-shell element, which has only translational degree of freedom like solid element, has been presented. The assumed nature strain (ANS) and enhanced assumed strain (EAS) methods can be used to remove several solid-shell locking problems. In this paper, ANS method was used for diminish transverse shear locking and EAS method for thickness locking. Using the element, the steel pipe making process from flat plate analyzed effectively, which is including bending and welding.

• Current Optics and Photonics
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• v.7 no.5
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• pp.496-503
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• 2023

We present a detailed analysis of the light extraction efficiency (LEE) of a core-shell nanorod light emitting diode (LED) using finite-difference time-domain (FDTD) simulations. We found that the LEE has a deep dependence on source positions and polarization directions based on the calculated LEE results for every x and z position inside the core-shell nanorod structure. The LEEs are different for the upper part (pyramid) and the lower part (sidewall) of the core-shell nanorod owing to total internal reflection (TIR) and the generated optical modes in the structure. As a result, the LEE of sidewall is much larger than that of pyramid. The averaged LEE of the core-shell nanorod LED is also investigated with variable p-GaN thickness, n-GaN thickness, and height for the design guidelines for the optimized LEE of core-shell nanorod LEDs.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.7
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• pp.1738-1750
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• 1994

Both cylindrical cup drawing and square cup drawing are analyzed using membrane analysis as well as shell analysis by the elastic-plastic finite element method. An incremental formulation incorporating the effect of large deformation and normal anisotropy is used for the analysis of elastic-plastic non-steady deformation. The computed results are compared with the existing experimental results to show the validity of the analysis. Comparisons are made in the punch load and distribution of thickness strain between the membrane analysis and the shell analysis for both cylindrical and square cup drawing processes. In punch load, both analyses show very little difference and also show generally good agreement with the experiment. For the cylindrical cup deep drawing, the computed thickness strain of a membrane analysis, however, shows a wide difference with the experiment. In the shell analysis, the thickness strain shows good agrement with the experiment. For the square cup deep drawing, both membrane and shell analyses show a wide difference with experiment, this may be attributable to the ignorance of the shear deformation. Concludingly, it has been shown that the membrane approach shows a limitation for the deep drawing process in which the effect of bending is not negligible and more exact information on the thickness strain distribution is required.

• Korean Journal of Poultry Science
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• v.10 no.1
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• pp.23-29
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• 1983

This study was carried out to investigate the variabilities of the thickness of egg shell and shell membrane of silky fowl egg from April 11, 1983 to May 14, 1983. One hundred and twenty eggs used in this experiment were obtained from a Synanmyun silky fowl farm, Sanchungkun, Gyeongnam province. The results obtained are summarized as follows: 1. Total items investigated for the silky fowl egg; egg weight, egg shell weight, egg shell thickness of sharp end, middle part, and blunt end, egg shell membrane thickness of snarp end, middle part, and blunt end, breaking strength, length of egg(L), width of egg(W), and L/W, were measured as 36.58${\pm}$0.446g, 4.53${\pm}$0.079g, 0.32${\pm}$0.006mm 0.32${\pm}$0.047mm, 0.30${\pm}$0.056mm, 0.050${\pm}$0.001mm, 0.050${\pm}$0.001mm, 0.053${\pm}$0.001mm, 3.06${\pm}$0.101kg, 4.80${\pm}$0.024mm, 3.82${\pm}$0.010cm, and 1.26${\pm}$0.005, respectively. 2. Correlation coefficients among 66 combinations of 12 items were estimated. The correlation coefficients relating to egg weight, egg shell weight, egg shell thickness of sharp end, middle part, and blunt end breaking strength, length of egg (L), width of egg (W), and L/W were largely to be highly significant but those related egg shell membrane thickness of sharp end middle part, and blunt end were not significant, sometimes showing inverse correlation

• Structural Engineering and Mechanics
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• v.55 no.2
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• pp.245-261
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• 2015

A three-dimensional (3-D) method of analysis is presented for determining the free vibration frequencies of eccentric hemi-spherical shells of revolution with variable thickness. Unlike conventional shell theories, which are mathematically two-dimensional (2-D), the present method is based upon the 3-D dynamic equations of elasticity. Displacement components $u_r$, $u_{\Theta}$, and $u_z$ in the radial, circumferential, and axial directions, respectively, are taken to be periodic in ${\theta}$ and in time, and algebraic polynomials in the r and z directions. Potential and kinetic energies of eccentric hemi-spherical shells with variable thickness are formulated, and the Ritz method is used to solve the eigenvalue problem, thus yielding upper bound values of the frequencies by minimizing the frequencies. As the degree of the polynomials is increased, frequencies converge to the exact values. Convergence to three or four-digit exactitude is demonstrated for the first five frequencies of the shells. Numerical results are presented for a variety of eccentric hemi-spherical shells with variable thickness.

• Structural Engineering and Mechanics
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• v.45 no.2
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• pp.259-275
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• 2013

Free vibration of symmetric angle-ply layered conical shell frusta of variable thickness is analyzed under shear deformation theory with different boundary conditions by applying collocation with spline approximation. Linear and exponential variation in thickness of layers are assumed in axial direction. Displacements and rotational functions are approximated by Bickley-type splines of order three and obtained a generalized eigenvalue problem. This problem is solved numerically for an eigenfrequency parameter and an associated eigenvector of spline coefficients. The vibration of three and five-layered conical shells, made up of two different type of materials are considered. Parametric studies are made for analysing the frequencies of the shell with respect to the coefficients of thickness variations, length-to-radius ratio, length-to-thickness ratio and ply angles with different combination of the materials. The results are compared with the available data and new results are presented in terms of tables and graphs.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1103-1114
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• 2000

Recent attempt to enhance the safety against collision reshaped the simple shell structures into the integrated complex shell structures. Moreover, due to various regulations continuously tightened for environment protection, weight reduction of automobiles becomes an increasingly important issue. Auto parts lightening is mainly accomplished by more reasonable design, adoption of lighter materials and miniaturization of the auto bodies. Focusing on the locally enhanced design approach among the above three ways, we here attempt to develop a patching optimization method, and also to determine the thicknesses of an integrated shell structure, both bringing a specified amount of stress relaxation. We first select a cross member as a patching optimization model. Based on the finite element stress calculations, we relieve the stress of cross member by patching in two ways-nonuniform thickness patching and optimized uniform thickness patching, the latter of which is more effective in a practical point of view for the preset amount of stress relaxation. Selecting a box type subframe as another finite element analysis model, we then determine the thickness of each part by axiomatic design approach for a preset amount of stress relaxation. The patching methodology and the axiomatic approach adopted in this work can be applied to the other complex shell structures such as center member and lower control arm.