• Communications of the Korean Mathematical Society
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• v.12 no.3
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• pp.619-629
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• 1997

In this paper, we give some properties of the sets $D_z(x_o, G)P_{G, z}(x)$. We also provide the relation between $P_{G, z}(x)$ and G$\hat{a}$teaux derivatives.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.6
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• pp.519-525
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• 2016

This paper addresses the framework of object-oriented image coding, describing a new algorithm, based on monodimensional Legendre polynomials, for texture approximation. Through the use of 1D orthogonal basis functions, the computational complexity which usually makes prohibitive most of 2D region-oriented approaches is significantly reduced, while only a slight increment of distortion is introduced. In the aim of preserving the bidimensional intersample correlation of the texture information as much as possible, suitable pseudo-bidimensional basis functions have been used, yielding significant improvements with respect to the straightforward 1D approach. The algorithm has been experimented for coding still images as well as motion compensated sequences, showing interesting possibilities of application for very low bitrate video coding.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.719-724
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• 1994

This paper describes a hybrid surface-based method for smooth 3D surface approximation to a sequence of 2D cross sections. The resulting surface is a hybrid G $^{1}$ surface represented by a mesh of triangular and rectangular Bezier patches defined on skinning, branching, or capping regions. Each skinning region is approximated with a closed B_spline surface, which is transformed into a mesh of Bezier patches. Triangular G $^{1}$ surfaces are constructed over brabching and capping regions such that the transitions between each capping regions such that the transitions between each triangular surface and its neighboring skinning surfaces are G $^{1}$ continuous. Since each skinning region is represented by an approximated rectangular C $^{2}$ suface instead of an interpolated trctangular G $^{[-1000]}$ surface, the proposed method can provide more smooth surfaces and realize more efficient data reduction than triangular surfacebased method.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.4
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• pp.335-341
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• 2009

In this paper, review of developed MLS-based finite elements and a proposal for their applications are described. The shape functions and their derivatives of MLS-based finite elements are constructed using Moving-Least Square approximation. In MLS-based finite element, using the adequate influence domain of weight function used in MLS approximation, kronecker delta condition could be satisfied at the element boundary. Moreover, because of the characteristics of MLS approximation, we could easily add extra nodes at an arbitrary position in MLS-based finite elements. For these reasons, until now, several variable-node elements(2D variable element for linear case and quadratic case and 3D variable-node elements) and finite crack elements are developed using MLS-based finite elements concept. MLS-based finite elements could be extended to 2D variable-node triangle element, 2D finite crack triangle element, variable-node shell element, finite crack shell element, and 3D polyhedron element. In this paper, we showed the feasibility of 3D polyhedron element at the case of femur meshing.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.12a
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• pp.93-96
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• 2000

In this paper, we suggest a feature points selection method using block-based watershed segmentation and polygon approximation for preprocessing of MPEG-4 mesh generation. 2D natural image is segmented by 8$\times$8 or 4$\times$4 block classification method and watershed algorithm. As this result, pixels on the watershed lines represent scene's interior feature and this lines are shapes of closed contour. Continuous pixels on the watershed lines are selected out feature points using Polygon approximation and post processing.

• Interaction and multiscale mechanics
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• v.3 no.2
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• pp.123-143
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• 2010

The essential idea of the element-free Galerkin method (EFG) is that moving least-squares (MLS) approximation are used for the trial and test functions with the variational principle (weak form). By using the weighted orthogonal basis function to construct the MLS interpolants, we derive the formulae for an improved element-free Galerkin (IEFG) method for solving three-dimensional problems in linear elasticity. There are fewer coefficients in improved moving least-squares (IMLS) approximation than in MLS approximation. Also fewer nodes are selected in the entire domain with the IEFG method than is the case with the conventional EFG method. In this paper, we selected a few example problems to demonstrate the applicability of the method.

• Journal of information and communication convergence engineering
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• v.6 no.3
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• pp.320-322
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• 2008

We present efficient algorithms for solving the piecewise-cubic approximation problems in the plane. Given a set D of n points in the plane, we find a piecewise-cubic polynomial curve passing through only the points of a subset S of D and approximating the other points using the uniform metric. The goal is to minimize the size of S for a given error tolerance $\varepsilon$, called the min-# problem, or to minimize the error tolerance $\varepsilon$ for a given size of S, called the min-$\varepsilon$ problem. We give algorithms with running times O($n^2$ logn) and O($n^3$) for both problems, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.11
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• pp.1043-1050
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• 2004

In this paper, Phase noise is analyzed and a novel approach of the nonlinear approximation including second order term of phase noise is presented to analyze and quantize system performance. As results, in QPSK-OFDM system, when PLL loop bandwidth is 5.0 Hz, 1.0 kHB, 0.5 kHz respectively, there are about 0.6 dB, 1.0 dB, 1.7 dB SNR penalties at BER=10$\^$-4/ compared with system without phase noise in AWGN channel. In 16QAM modulation, there are about 1.9 dB, 3.2 dB, 6.7 dB SNR penalties at BER=10$\^$-4/ respectively. At QPSK-OFDM system, comparing the previous linear approximation method with our proposed nonlinear approximation method, there is similar BER performance at phase noise variance lower than 0.02, but certain difference occurs as variance increases more than 0.02. Furthermore, analytical BER results closely match with simulation results in the OFDM system employing QPSK and 16qAM modulation. And, BER performance of QPSK-OFDM system is considerably degraded because of the BER error floor if the phase noise variance becomes larger than 0.03.

• Journal of applied mathematics & informatics
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• v.31 no.5_6
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• pp.609-621
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• 2013

At present, research on providing new methods to solve nonlinear integral equations for minimizing the error in the numerical calculations is in progress. In this paper, necessary conditions for existence and uniqueness of solution for nonlinear 2D Fredholm integral equations are given. Then, two different numerical solutions are presented for this kind of equations using 2D shifted Legendre polynomials. Moreover, some results concerning the error analysis of the best approximation are obtained. Finally, illustrative examples are included to demonstrate the validity and applicability of the new techniques.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1481-1486
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• 2013

In this paper, a new two dimensional (2D) analytical model of a Dual Material Gate tunnel field effect transistor (DMG TFET) is presented. The parabolic approximation technique is used to solve the 2-D Poisson equation with suitable boundary conditions. The simple and accurate analytical expressions for surface potential and electric field are derived. The electric field distribution can be used to calculate the tunneling generation rate and numerically extract tunneling current. The results show a significant improvement of on-current and reduction in short channel effects. Effectiveness of the proposed method has been confirmed by comparing the analytical results with the TCAD simulation results.