• Structural Engineering and Mechanics
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• v.8 no.6
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• pp.623-637
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• 1999

This paper presents a four-noded quadrilateral $C^0$ strain plate element for the analysis of thick laminated composite plates. The element formulation is based on: 1) the third-order shear deformation theory; 2) assumed strain element formulation; and 3) interrelated edge displacements and rotations along element boundaries. Unlike the existing displacement-type composite plate elements based on the third-order theory, which rely on the $C^1$-continuity formulation, the present plate element is of $C^0$-continuity, and its element stiffness matrix is evaluated explicitly. Because of the third-order expansion of the in-plane displacements through the thickness, the resulting theory and hence elements do not need shear correction factors. The explicit element stiffness matrix makes the present element more computationally efficient than the composite plate elements using numerical integration for the analysis of thick layered composite plates.

• 전기의세계
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• v.20 no.5
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• pp.19-22
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• 1971

This paper deals with the state-variable analysis of the arbitrary RLC lumped linear time-invariant networks. A formulation technique for determining a set of state equation using Bryant-Bashkow A Matrix and by means of the procedure setting up the terminal equation is discussed.

• The Mathematical Education
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• v.28 no.1
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• pp.57-61
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• 1989

• Journal of Mechanical Science and Technology
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• v.19 no.spc1
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• pp.283-291
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• 2005

Accurate seismic analyses of large deformable moving structures are still unsolved problems in the field of earthquake engineering. In order to analyze these problems, the nonlinear finite element method formulated by the absolute nodal coordinate approach is noticed. Because, this formulation has several advantages over the standard procedures on mass matrix, elastic forces and damping forces in the case of large displacement problems. But, it has not been fully studied to build frame structure models by using beam elements in the absolute nodal coordinate formulation. In this paper, we propose the connecting method of the beam elements formulated by the absolute nodal coordinate. The coordinate transformation matrix of this element is introduced into the frame structure. This beam element has the characteristic that the mass matrix and bending stiffiness matrix are constant even if in the case of large displacement problems, and this characteristic is being kept after the transformation. In order to verify the proposed method, we show the numerical simulation results of frame structures for a vibration problem and a large displacement problem.

• Coupled systems mechanics
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• v.10 no.6
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• pp.509-520
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• 2021

Fiber-reinforced concrete (FRC) is a composite material where small fibers made from steel or polypropylene or similar material are embedded into concrete matrix. In a material model each constituent should be adequately described, especially the interface between the matrix and fibers that is determined with the 'bond-slip' law. 'Bond-slip' law describes relation between the force in a fiber and its displacement. Bond-slip relation is usually obtained from tension laboratory experiments where a fiber is pulled out from a matrix (concrete) block. However, theoretically bond-slip relation could be determined from bending experiments since in bending the fibers in FRC get pulled-out from the concrete matrix. We have performed specially designed laboratory experiments of three-point beam bending with an intention of using experimental data for determination of material parameters. In addition, we have formulated simple layered model for description of the behavior of beams in the three-point bending test. It is not possible to use this 'forward' beam model for extraction of material parameters so an inverse model has been devised. This model is a basis for formulation of an inverse model that could be used for parameter extraction from laboratory tests. The key assumption in the developed inverse solution procedure is that some values in the formulation are known and comprised in the experimental data. The procedure includes measured data and its derivative, the formulation is nonlinear and solution is obtained from an iterative procedure. The proposed method is numerically validated in the example at the end of the paper and it is demonstrated that material parameters could be successfully recovered from measured data.

• Structural Engineering and Mechanics
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• v.42 no.1
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• pp.39-53
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• 2012

This paper presents an alternative way to derive the exact element stiffness matrix for a beam on Winkler foundation and the fixed-end force vector due to a linearly distributed load. The element flexibility matrix is derived first and forms the core of the exact element stiffness matrix. The governing differential compatibility of the problem is derived using the virtual force principle and solved to obtain the exact moment interpolation functions. The matrix virtual force equation is employed to obtain the exact element flexibility matrix using the exact moment interpolation functions. The so-called "natural" element stiffness matrix is obtained by inverting the exact element flexibility matrix. Two numerical examples are used to verify the accuracy and the efficiency of the natural beam element on Winkler foundation.

• Journal of Pharmaceutical Investigation
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• v.40 no.5
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• pp.313-319
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• 2010

The objectives of this study were to evaluate the effect of formulation ingredients on the drug release and to optimize the novel sustained release matrix tablet formulations of bupropion hydrochloride. A three factor, three-level Box-Behnken design was used for the optimization procedure, with the amounts of PEO ($X_1$), citric acid ($X_2$) and Compritol 888 ATO ($X_3$) as the independent variables. The selected dependent variables were the cumulative percentage values of bupropion hydrochloride that had dissolved after 1, 4 and 8 hr. Various dissolution profiles of the drug from sustained release matrix tablets were obtained. Optimization was performed for $X_1$, $X_2$ and $X_3$ using the following target ranges; $30%{\leq}Y_1{\leq}45%$; $70{\leq}Y_2{\leq}85%$; $85%{\leq}Y_3{\leq}100%$. The optimized formulation for bupropion hydrochloride was achieved with 12.5% PEO ($X_1$), 2.5% citric acid ($X_2$) and 10% Compritol 888 ATO ($X_3$). The sustained release matrix tablets with the optimized formulation provided a release profile that was close to predicted values. In addition, the dissolution profiles of the sustained release matrix tablet with the optimized formulation were similar to those of the commercial product Wellbutrin$^{(R)}$ SR tablets ($f_2$=79.83).

• The Journal of the Acoustical Society of Korea
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• v.16 no.3E
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• pp.32-36
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• 1997

This study models mobile communication channels as a discrete finite Markovian process, and Markovian jump linear system having parallel Kalman filter type is applied. What is newly proposed in this paper is an equation for obtaining the transition matrix according to sampling time by using a weighted Gaussian sum approximation and its simple calculation process. Experiments show that the proposed method has superior performance and reuires computation compared to the existing MJLS using the ransition matrix given by a statistical method or from priori information.

• Proceeding of KASS Symposium
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• 2006.05a
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• pp.256-264
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• 2006

This paper describes the formulation of rectangular flat shell element that is modeled with the six degree of freedoms including a rotational degree of freedom. The rectangular finite element matrix with a rotational degree of freedom is developed using a beam stiffness matrix and compared with other methods. The outputs of the quantity of vertical deflection of cantilever beam show us the improving evidence of the Frame-Shell finite element matrix in a calculation of vertical deflections of cantilever beam.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.292.1-292.1
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• 2003

Purpose. To develop a new heterodisperse 650mg acetaminophen HPMC matrix tablet with biphasic sustained release profiles. Methods. Hydroxypropylmethylcellulose(HPMC) matrix tablets were prepared by wet-granulating drug with other excipients, followed by direct compression of the dried granule mixtures into tablet using a rotary tablet machine. (omitted)