• Journal of applied mathematics & informatics
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• v.12 no.1_2
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• pp.429-436
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• 2003

We study the asymptotic equivalence between the nonlinear differential system $\chi$'(t) = f(t, $\chi$(t)) and its variational system ν'(t) = f$\chi$(t, 0)ν(t) by using the comparison principle and notion of strong stability.

• Communications of the Korean Mathematical Society
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• v.20 no.2
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• pp.351-358
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• 2005

We study asymptotic equivalence between nonlinear difference system $$\Delta\chi(n)=f(n,\chi(n))$$ and its variational system $${\Delta}v(n)=f_{\chi}(n,0)v(n)$$.

• Bulletin of the Korean Mathematical Society
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• v.44 no.1
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• pp.177-184
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• 2007

We study the asymptotic behavior of nonlinear Volterra difference system $$x(n+1)=f(n,x(n))+{\sum\limits^{n}_{s=n_{o}}\;g(n,s,x(s)),\;x(n_{o})=xo$$ by using the resolvent matrix R(n, m) of the corresponding linear Volterra system and the comparison principle.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.5
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• pp.614-620
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• 1998

In this paper, we analyze theoritically the propagation and radiation characteristics for elliptical corrugated waveguides. The solutions of wave equations in an elliptic cylinder system are obtained in terms of Mathieu functions of 1st and 2nd kind. The electromagnetic fields in the elliptical corrugated waveguide can be represented by series and products of angular and radial Mathieu functions. By using impedence matching at the boundary between the inner region and the slot region, characteristic equations are derived. Then the characteristic equation is solved for $HE_{11}$ mode which is dominant mode in the elliptical corrugated waveguide and the fields in the aperture is calculated. And the propagation pattern for the elliptical corrugated waveguides is calculated through the field equivalence principle.

• Proceedings of the Korean Statistical Society Conference
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• 2002.11a
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• pp.293-298
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• 2002

We propose an improved version of Kim (2000) to the effect that in principle we may deal with a graphical model of any size. Kim (2000) proposed a method of estimating parameters for a model of categorical variables which is too large to handle as a single model. We applied the proposed method to a simulated data of 158 binary variables.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.5
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• pp.666-671
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• 1990

The characteristics of the corrugated conical horn antenna for the satellite communication earth station operating at C band is analyzed and its radiation patterns is measured. We obtain the characterstic equations for corrugated horn in the condition that the balanced hybrid mode is formed on born aperture and calculate radiation patterns in the Fresnel region from the aperture integral expressions obtained by the equivalence principle. The radiation patterns which are calculated for the frequency of 3.85GHz and 6.18GHz are well agreed with the measured data.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.9
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• pp.1236-1243
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• 1995

The propagation characteristics of the symmetric and the asymmetric shielded coplanar waveguide with finite metallization thickness is analyzed by boundary integral method employing the equivalence principle. Since the Green's function and the basis functions are composed of sinusoidal functions, the integration in Galerkin's method is solved analytically. The propagation constants of the fundamental and the first higher order mode are obtained and the effects of strip thickness, substrate permittivity, and the asymmetry of the structure are calculated.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.2
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• pp.19-24
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• 1998

The problem of Smith-Purcell radiation by a strip grating over a groundeddielectric slabl is analyzed by use of the equivalence principle, Floquet's theorem, and the method of moment. the relative radiation intensities of the space harmonics, computed by use of the proposed method, for the appropriately chosen charge velocities and grating dimensions are presented. In particular, some relationships between the smith-purcell radiation and the leaky-wave radiation in the proposed geometry are investigated.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.18-21
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• 1987

The problem of electromagnetic scattering from arbitrarily shaped lossy dielectric bodies of revolution is studied. Two coupled vector integral equations are formulated from the potential formulas, the equivalence principle and boundary condition. The unknown surface currents (both electric and magnetic) can be found by the moment method, Galerkins's procedure. After the surface currents are determined, the scattering pattern can be evaluated.

• Journal for History of Mathematics
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• v.32 no.1
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• pp.17-25
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• 2019

This essay elucidates the way the geometries of space-time theories explain material bodies' motions. A conventional attempt to interpret the way that space-time geometry explains is to consider the geometrical structure of space-time as involving a causally efficient entity that directs material bodies to follow their trajectories corresponding to the laws of motion. Newtonian substantival space is interpreted as an entity that acts but is not acted on by the motions of material bodies. And Einstein's curved space-time is interpreted as an entity that causes the motions of bodies. This essay argues against this line of thought and provides an alternative understanding of the way space-time geometry explain the laws of motion. The workings of the way that Newton's flat and Einstein's curved space-time explains the law of motion is such that space-time geometry encodes the principle of inertia which specifies straight lines of moving bodies.