• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.2
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• pp.139-143
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• 1988

A new measurement method of coupled transmission line characteristics is described. This method presents precision values of even-and odd-mode impedances as well as effective dielectric constants of symmetric parallel coupled microstrip lines from the scalar quantities obtained by transmission coefficients at two different resonance frequencies. Especially these values include dispersion effects in the measured frequency band. The measured impedances and effective dielectric constants of actually fabricated coupled lines on the Teflon substrates with low dielectric constants are good agreement with predicted values. And the experimental pass band characteristics of single section resonator by using previously designed coupled lines agree well with theoretical values.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.92-94
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• 1995

This paper is to describe a method for calculating resistance of cage rotor end-ring, based on 3-D finite element method using magnetic vector potential $\vec{A}$ and electric scalar potential ${\phi}$. The induced current of a cage rotor flows through the bars of a cage rotor. The current completes their closed paths by passing around the end-ring. The end-ring may contribute a significant influence to the performance of machine. The resistance under consideration of skin effect is calculate by using Joule's loss equation.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.23 no.3
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• pp.211-236
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• 2019

This paper is devoted to the study and investigation of the Runge-Kutta discontinuous Galerkin method for a system of differential equations consisting of two hyperbolic conservation laws. The numerical coupling flux which is used at a given interface (x = 0) is the upwind flux. Moreover, in the linear case, we derive optimal convergence rates in the $L_2$-norm, showing an error estimate of order ${\mathcal{O}}(h^{k+1})$ in domains where the exact solution is smooth; here h is the mesh width and k is the degree of the (orthogonal Legendre) polynomial functions spanning the finite element subspace. The underlying temporal discretization scheme in time is the third-order total variation diminishing Runge-Kutta scheme. We justify the advantages of the Runge-Kutta discontinuous Galerkin method in a series of numerical examples.

• Journal of applied mathematics & informatics
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• v.41 no.6
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• pp.1341-1364
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• 2023

This article introduces a method for estimating the conditional hazard function of a real-valued response variable based on a functional variable. The method uses local linear estimation of the conditional density and cumulative distribution function and is applied to a functional stationary ergodic process where the explanatory variable is in a semi-metric space and the response is a scalar value. We also examine the uniform almost complete convergence of this estimation technique.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.4
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• pp.310-317
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• 2017

Recently, many nations are operating and developing Global Navigation Satellite System (GNSS). Also, Satellite Based Augmentation System (SBAS), which uses the geostationary orbit, is operated presently in order to improve the performance of GNSS. The most widely-used SBAS is Wide Area Augmentation System (WAAS) of GPS developed by the United States. SBAS uses various algorithms to offer guaranteed accuracy, availability, continuity and integrity to its users. There is algorithm for guarantees the integrity of the satellite. This algorithm calculates the satellite errors, generates the correction and provides it to the users. The satellite orbit errors are calculated in three-dimensional space in this step. The reference placement is crucial for this three-dimensional calculation of satellite orbit errors. The wider the reference placement becomes, the wider LOS vectors spread, so the more the accuracy improves. For the next step, the regional features of the US and Korea need to be analyzed. Korea has a very narrow geographic features compared to the US. Hence, there may be a problem if the three-dimensional space method of satellite orbit error calculation is used without any modification. This paper suggests a method which uses scalar values to calculate satellite orbit errors instead of using three-dimensional space. Also, this paper proposes the feasibility for this method for a narrow area. The suggested method uses the scalar value, which is a projection of orbit errors on the LOS vector between a reference and a satellite. This method confirms the change in errors according to the baseline distance between Korea and America. The difference in the error change is compared to present the feasibility of the proposed method.

• 한국연소학회:학술대회논문집
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• 2003.05a
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• pp.191-194
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• 2003

The present study is focused on the subgrid scale combustion model in context with a Large Eddy Simulation. In order to deal with detailed chemical kinetic, the level-set method based on a flamelet model is addressed. In this model, the flame front is treated as an interface, represented by an iso-surface of a scalar field G. This iso-surface is convected by the velocity field and its filtered quantities are include the turbulent burning velocity, which is to be modelled. For modelling the turbulent burning velocity, an equation for the length-scale of the sub-filter flame front fluctuations was developed. The formulations and issues for the turbulent premixed and partially premixed flames are addressed in detail.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.803-808
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• 2012

We have implemented two-component spin-orbit relativistic effective core potential (SOREP) methods in an all-electron relativistic program DIRAC. This extends the capacity of the two-component SOREP method to many ground and excited state calculations in a single program. As the test cases, geometries and energies of the small halogen molecules were studied. Several two-component methods are compared by using spin-orbit and scalar relativistic effective core potentials. For the $I_2$ molecule, excitation energies of low-lying excited states agree well with those from corresponding all-electron methods. Efficiencies in SOREP calculations enhanced by using symmetries are also discussed briefly.

• Communications of the Korean Mathematical Society
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• v.20 no.3
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• pp.563-578
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• 2005

In [Z. Cai and B. C. Shin, SIAM J. Numer. Anal. 40 (2002), 307-318], we developed the discrete first-order system least squares method for the second-order elliptic boundary value problem by directly approximating $H(div){\cap}H(curl)-type$ space based on the Helmholtz decomposition. Under general assumptions, error estimates were established in the $L^2\;and\;H^1$ norms for the vector and scalar variables, respectively. Such error estimates are optimal with respect to the required regularity of the solution. In this paper, we study solution methods for solving the system of linear equations arising from the discretization of variational formulation which possesses discrete biharmonic term and focus on numerical results including the performances of multigrid preconditioners and the finite element accuracy.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.3
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• pp.91-102
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• 1994

For the analysis of textured image, it requires large storage space and computation time to calculate the matrix features such as SGLDM(Spatial Gray Level Dependence Matrix). NGLDM(Neighboring Gray Level Dependence Matrix). NSGLDM(Neighboring Spatial Gray Level Dependence Matrix) and GLRLM(Gray Level Run Length Matrix). In spite of a large amount of information that each matrix contains, a set of several correlated scalar features calculated from the matrix is not sufficient to approximate it. In this paper, we propose a new classifier for textured images based on these matrices in which the projected vectors of each matrix on the meaningful directions are used as features. In the proposed method, an unknown image is classified to the class of a known image that gives the maximum similarity between the projected model vector from the known image and the vector from the unknown image. In the experiment to classify images of agricultural products, the proposed method shows good performance as much as 85-95% of correct classification ratio.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.1
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• pp.8-15
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• 1998

An analysis of the microstripline is started as an assumption of the axial & transveral current distribution. Applying the boundary conditions to the scalar wave equations of a electric & magnetic potential, the two simultaneous coupled integral equations are produced. The electronmagnetic fields in microstrip line can be obtained by solving these two coupled integral equaltion. In general, either a numerical analysis method or a Galerkin method was used to solve them. In this paper, a residue theorem is proposed to solve them. The electromagnetic fields are expressed as integral equations for LSE and LSM mode in the spectral domain. Applying a residue theorem to the Fourier transformed equation and Fourier inverse transformed equation which is necessary for interchanging the space domain and the spectral domain, the electromagnetic fields are expressed as algebraic equations whichare relatively easier to handle. the distributions of the electromagnetic field are shown at the range of -5w/2.leq.x.leq.5w/2, 0.lep.y.leq.4h for z=0. It agrees well with the results of the Quasi-TEM mode analysis.