• 전기의세계
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• v.24 no.6
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• pp.97-101
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• 1975

The electrical neuronal model described in this paper simulates the most important functional properties of nerve cells. An model circuit incorporating many of the digital and analog properties of neurons is described. Having such properties as variable threshold level, action potential, summation, all-or-none output, absolute and relative refract oriness, and ingibition, it exhibits a considerable amount of functional equivalence to biological structures. This electrical neuronal model has utility not only for studying single unit properties but also for investigating group interactions. Such studies may be relevent to elucidation of neuronal network behavior.

• Korean Journal of Mathematics
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• v.28 no.4
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• pp.791-802
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• 2020

We obtain a two variable generating function for the number of triangular partitions. Using this generating function, we study arithmetic properties of a certain weighted count of triangular partitions. Finally, we introduce a rank-type function for triangular partitions, which gives a combinatorial explanation for a triangular partition congruence.

• Geomechanics and Engineering
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• v.22 no.1
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• pp.65-80
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• 2020

This paper presents a theoretical investigation on the response of the thermo-mechanical bending of FG plate on variable elastic foundation. A quasi-3D higher shear deformation theory is used that contains undetermined integral forms and involves only four unknowns to derive. The FG plates are supposed simply supported with temperature-dependent material properties and subjected to nonlinear temperature rise. Various homogenization models are used to estimate the effective material properties such as temperature-dependent thermoelastic properties. Equations of motion are derived from the principle of virtual displacements and Navier's solution is used to solve the problem of simply supported plates. Numerical results for deflections and stresses of FG plate with temperature-dependent material properties are investigated. It can be concluded that the proposed theory is accurate and simple in solving the thermoelastic bending behavior of FG thick plates.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.419-426
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• 2001

Industrial products determined by fixed size posses definite limits variety by manufacture tolerance in existence. The optimum value solved by deterministic approaches do not account of tolerance bands of design variables and material properties. If we examine optimum value considering tolerance bands of design variables and material properties, it might be useless, owing to exist infeasible region. We have two ways to prevent being useless value. The one is to minimize tolerance band, the other is to consider tolerance band in optimum design. The former needed more accuracy during manufacturing process require higher production cost, the letter is more appropriate to consider tolerance band. In this research, we consider the tolerance bands of all variables, which might have the tolerance bands used in the problem, based on optimum value of deterministic approaches. Orthogonal arrays are used to minimize the number of trial. Tolerance bands are supposed discretionary according to design variable. Appropriateness suggested by this research is examined through two examples. Mathematical problem is investigated only in terms of tolerance bands of design variables, and cantilever beam problem is explained through tolerance bands of design variable, material properties and loading conditions. It is proved that values from the presented method are satisfactory for tolerance bands of variables.

• Journal of the Korean Data and Information Science Society
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• v.27 no.6
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• pp.1653-1660
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• 2016

Smoothly clipped absolute deviation (SCAD) penalty is known to satisfy the desirable properties for penalty functions like as unbiasedness, sparsity and continuity. In this paper, we deal with the regression function estimation and variable selection based on SCAD penalized censored regression model. We use the local linear approximation and the iteratively reweighted least squares algorithm to solve SCAD penalized log likelihood function. The proposed method provides an efficient method for variable selection and regression function estimation. The generalized cross validation function is presented for the model selection. Applications of the proposed method are illustrated through the simulated and a real example.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.1
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• pp.90-100
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• 1993

This paper presents some inherent characteristics of a semi-active variable damper featuring electro-rheological (ER) fluid. The damping force of the damper can be selectively adjusted or controlled by employing electric field to the ER fluid domain. This is possible owing to the pressure drop across the piston occured by field-dependent variable yield stress of the ER fluid. This is fundamentally different than the performance of a conventional adjustable viscous damper. To demonstrate the effectiveness and superiority over the conventional one, the proposed damper is incorporated with a suspension system. A quarter car model with the suspension system is formulated and represented by a state equation. By choosing numerical values based on realistic package size, power requirements and suitable ER properties, the performance characteristics of the suspension system are obtained and evaluated in both frequency and time domains. The effects of constant electric field and on-off controlled electric field which relates to the damping force are also examined.

• Communications for Statistical Applications and Methods
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• v.22 no.2
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• pp.147-157
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• 2015

We consider a sparse high-dimensional linear regression model. Penalized methods using LASSO or non-convex penalties have been widely used for variable selection and estimation in high-dimensional regression models. In penalized regression, the selection and prediction performances depend on which penalty function is used. For example, it is known that LASSO has a good prediction performance but tends to select more variables than necessary. In this paper, we propose an additive sparse penalty for variable selection using a combination of LASSO and minimax concave penalties (MCP). The proposed penalty is designed for good properties of both LASSO and MCP.We develop an efficient algorithm to compute the proposed estimator by combining a concave convex procedure and coordinate descent algorithm. Numerical studies show that the proposed method has better selection and prediction performances compared to other penalized methods.

• Journal of Korean Society for Quality Management
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• v.32 no.4
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• pp.252-264
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• 2004

Variable sampling Interval (VSI) control charts vary the sampling interval according to value of the control statistic while the sample size is fixed. It is known that control charts with 2-state VSI scheme, which uses only two sampling intervals, give good statistical properties. Variable sample size (VSS) control charts vary the sample size according to value of the control statistic while the sampling interval is fixed. In the VSS scheme no optimal results are known for the number of sample sizes. It is also known that the variable sampling rate (VSR) $\bar{X}$ control chart with 2-state VSS and 2-state VSI scheme leads to large improvements In performance over the fixed sampling rate (FSR) $\bar{X}$ chart, but the optimal number of states for sample size Is not known. In this paper, the VSR Χ charts with multi-state VSS and 2-state VSI scheme are designed and compared to 2-state VSS and 2-state VSI scheme. The multi-state VSS scheme is considered to, achieve an additional improvement by switching from the 2-state VSS scheme. On the other hand, the multi-state VSI scheme is not considered because the 2-state scheme is known to be optimal. The 3-state VSS scheme improves substantially the sensitivity of the $\bar{X}$ chart especially for small and moderate mean shifts.

• Spatial Information Research
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• v.18 no.5
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• pp.13-26
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• 2010

In this paper, a dynamic variable window-based topographical classification method is proposed which has the changeable classification units depending on topographical properties. In the proposed scheme, to im prove the classification efficiency, the unit of topographical classification can be changeable dynamically according to the topographical properties and repeated patterns. Also, in this paper, the classification efficiency and accuracy of the proposed method are analyzed in order to find an optimal maximum decision window-size through the experiment. According to the experiment results, the proposed dynamic variable window-based topographical classification method maintains similar accuracy but remarkably reduce computing time than that of a fixed window-size based one, respectively.

• Structural Engineering and Mechanics
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• v.66 no.6
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• pp.737-748
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• 2018

The current study presents a new technique in the framework of the nonlocal elasticity theory for a comprehensive buckling analysis of Euler-Bernoulli nano-beams made up of bidirectional functionally graded material (BDFGM). The mechanical properties are considered by exponential and arbitrary variations for axial and transverse directions, respectively. The various circumstances including tapering, resting on two-parameter elastic foundation, step-wise or continuous variations of axial loading, various shapes of sections with various distribution laws of mechanical properties and various boundary conditions like the multi-span beams are taken into account. As far as we know, for the first time in the current work, the buckling analyses of BDFGM nano-beams are carried out under mentioned circumstances. The critical buckling loads and mode shapes are calculated by using energy method and a new technique based on calculus of variations and collocation method. Fast convergence and excellent agreement with the known data in literature, wherever possible, presents the efficiency of proposed technique. The effects of boundary conditions, material and taper constants, foundation moduli, variable axial compression and small-scale of nano-beam on the buckling loads and mode shapes are investigated. Moreover the analytical solutions, for the simpler cases are provided in appendices.