• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.6 no.1
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• pp.1-15
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• 2002

Advection-dominated transport problems possess difficulties in the design of numerical methods for solving them. Because of the hyperbolic nature of advective transport, many characteristic numerical methods have been developed such as the classical characteristic method, the Eulerian-Lagrangian method, the transport diffusion method, the modified method of characteristics, the operator splitting method, the Eulerian-Lagrangian localized adjoint method, the characteristic mixed method, and the Eulerian-Lagrangian mixed discontinuous method. In this paper relationships among these characteristic methods are examined. In particular, we show that these sometimes diverse methods can be given a unified formulation. This paper focuses on characteristic finite element methods. Similar examination can be presented for characteristic finite difference methods.

• Journal for History of Mathematics
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• v.32 no.1
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• pp.27-44
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• 2019

This study analyses and discusses on the characteristic and the origin of the exhaustion method caused by the controversy over whether that method succeeded to the Antiphone's complete exhaustion idea and whether that method is similar to the method of limits. First, this study analyses 'principle of exhaustion method' which play an important role in that method in order to grasp the local characteristic of it. And this study speculates the origin of the exhaustion method by considering the time and situation of appearance and looking through the local characteristic of it. Also, this study takes a view of the overall characteristic of the exhaustion method by inquiring into the process of actual application of 'principle of exhaustion method' in a proof. As these results, this study reveals that the exhaustion method uprose not as a succession of Antiphone's idea but as a reaction to its idea, and that the exhaustion method has the recognized character of 'finitude' as distinct from the method of limits.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1585-1591
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• 2009

This paper describes a new method for extracting characteristic impedance of transmission line using Substrate Integrated Artificial Dielectric (SIAD). The new procedure to calculate the characteristic impedance of SIAD transmission line is described with the proper equations and basic transmission line theory. The characteristic impedance is determined as an almost fixed value in the proposed method, while it fluctuates according to frequency in the previous method. As the result, the effective dielectric constant of SIAD transmission line is calculated as a fixed value rather than fluctuating one. In order to show the validity of the proposed method, SIAD microstrip lines are simulated and measured, and characteristic impedances and effective dielectric constant are calculated and compared to the previous method.

• Journal of applied mathematics & informatics
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• v.34 no.1_2
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• pp.19-34
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• 2016

In this paper, we present a split least-squares characteristic mixed finite element method(MFEM) to get the approximate solutions of the convection dominated Sobolev equations. First, to manage both convection term and time derivative term efficiently, we apply a least-squares characteristic MFEM to get the system of equations in the primal unknown and the flux unknown. Then, we obtain a split least-squares characteristic MFEM to convert the coupled system in two unknowns derived from the least-squares characteristic MFEM into two uncoupled systems in the unknowns. We theoretically prove that the approximations constructed by the split least-squares characteristic MFEM converge with the optimal order in L² and H¹ normed spaces for the primal unknown and with the optimal order in L² normed space for the flux unknown. And we provide some numerical results to confirm the validity of our theoretical results.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.8
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• pp.432-437
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• 2004

Since the characteristic frequency is decreased in proportion to the fault distance, the characteristic frequency component may be insufficiently eliminated by a low-pass filter on a long transmission line. In order to set a standard for the cut-off frequency of the low-pass filter, this paper proposes a method for obtaining the characteristic frequencies due to line faults. The application results of the proposed method are presented for line to ground (LG) faults and line to line (LL) faults on a 345 kV 200 km overhead transmission line. The EMTP is used to generate fault signals under different fault locations and fault inception angles. By comparison between the characteristic frequencies obtained from the proposed method and the EMTP simulation, it is shown that the proposed method accurately obtains the characteristic frequency.

• Journal of Korean Society for Quality Management
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• v.32 no.4
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• pp.265-273
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• 2004

We got the growth distance curve by spline smoothing method with observed marketing data and the growth velocity curve by the derivation of the growth distance curve. Using this growth velocity curve, we defined the several characteristic points which describe the variation of marketing data. In this paper, to specify several patterns of marketing data, we suggested characteristic function by using these characteristic points. In addition, we applied characteristic function to the seventeen brands of electric home products data.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.318-327
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• 2010

This paper deals with analysis on dynamic characteristic and circuit parameter of linear switched reluctance motor by electromagnetic analytical method. Above all, using space harmonic method, which is electromagnetic method, the air-gap flux density is analyzed in the both align and unaign positions, and the inductance profile, force characteristic and resistance per phase are calculated by means of the process. The validity of the analyzed results are demonstrated by the finite element method(FEM) and manufacture of the prototype machine. Second, the dynamic simulation is analyzed by the use of circuit parameters derived from analytical method, and the operating system of the prototype machine is manufactured to demonstrated the validity of simulation analysis. As a result, it is considered that the characteristic equation suggested in this paper will contribute to the design, analysis and application of LSRM.

• East Asian mathematical journal
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• v.35 no.5
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• pp.569-587
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• 2019

In this paper, we consider a split least-squares characteristic mixed element method for Sobolev equations with a convection term. First, to manipulate both convection term and time derivative term efficiently, we apply a characteristic mixed element method to get the system of equations in the primal unknown and the flux unknown and then get a least-squares minimization problem and a least-squares characteristic mixed element scheme. Finally, we obtain a split least-squares characteristic mixed element scheme for the given problem whose system is uncoupled in the unknowns. We prove the optimal order in $L^2$ and $H^1$ normed spaces for the primal unknown and the suboptimal order in $L^2$ normed space for the flux unknown.

• Bulletin of the Korean Mathematical Society
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• v.54 no.4
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• pp.1409-1419
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• 2017

We introduce an extrapolated Crank-Nicolson characteristic finite element method to approximate solutions of a convection dominated Sobolev equation. We obtain the higher order of convergence in both the spatial direction and the temporal direction in $L^2$ normed space for the extrapolated Crank-Nicolson characteristic finite element method.

• East Asian mathematical journal
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• v.33 no.3
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• pp.295-308
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• 2017

We introduce a Crank-Nicolson characteristic finite element method to construct approximate solutions of a nonlinear Sobolev equation with a convection term. And for the Crank-Nicolson characteristic finite element method, we obtain the higher order of convergence in the temporal direction and in the spatial direction in $L^2$ normed space.