• Journal of the Korean Mathematical Society
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• v.48 no.2
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• pp.267-288
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• 2011

In this paper, we construct eight infinite families of ternary linear codes associated with double cosets with respect to certain maximal parabolic subgroup of the special orthogonal group $SO^-$(2n, q). Here q is a power of three. Then we obtain four infinite families of recursive formulas for power moments of Kloosterman sums with square arguments and four infinite families of recursive formulas for even power moments of those in terms of the frequencies of weights in the codes. This is done via Pless power moment identity and by utilizing the explicit expressions of exponential sums over those double cosets related to the evaluations of "Gauss sums" for the orthogonal groups $O^-$(2n, q).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.2
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• pp.196-203
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• 2015

In order to apply cylindrical periodic array to phased array antenna or frequency selective surface, efficient electromagnetic analysis is required. Finite periodic array is applied in real situation. But, generally, assumed that periodic structure is arranged infinitely, approximate electromagnetic characteristics can be obtained efficiently. But, difference of characteristics between real structure and approximate structure occurs because finite periodic array is approximated to infinite periodic array. Therefore, comparison and analysis of cylindrical infinite array and finite array are required. In this paper, cylindrical infinite periodic array are analyzed using cylindrical Floquet harmonics. Also, cylindrical finite periodic array is analyzed using method of moments (MoM) with thin wire approximation because periodic structures which are composed of strip with narrow width are analyzed. Transmission characteristics and surface currents of infinite and finite periodic structures are compared.

• Journal of the Korean Mathematical Society
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• v.57 no.3
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• pp.585-602
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• 2020

In this paper, we construct four infinite families of binary linear codes associated with double cosets with respect to a certain maximal parabolic subgroup of the orthogonal group O⁺(2n, 2^r). And we obtain two infinite families of recursive formulas for the power moments of Kloosterman sums and those of 2-dimensional Kloosterman sums in terms of the frequencies of weights in the codes. This is done via Pless' power moment identity and by utilizing the explicit expressions of exponential sums over those double cosets related to the evaluations of "Gauss sums" for the orthogonal groups O⁺(2n, 2^r).

• Structural Engineering and Mechanics
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• v.23 no.6
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• pp.599-613
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• 2006

A method for the dynamical analysis of FE discretized uncertain linear and nonlinear structures is presented. This method is based on the moment equation approach, for which the differential equations governing the response first and second-order statistical moments must be solved. It is shown that they require the cross-moments between the response and the random variables characterizing the structural uncertainties, whose governing equations determine an infinite hierarchy. As a consequence, a closure scheme must be applied even if the structure is linear. In this sense the proposed approach is approximated even for the linear system. For nonlinear systems the closure schemes are also necessary in order to treat the nonlinearities. The complete set of equations obtained by this procedure is shown to be linear if the structure is linear. The application of this procedure to some simple examples has shown its high level of accuracy, if compared with other classical approaches, such as the perturbation method, even for low levels of closures.

• Interaction and multiscale mechanics
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• v.3 no.4
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• pp.343-363
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• 2010

The present paper is concerned with vibrations of an elastic bridge loaded by a moving elastic beam of a finite length, which is an extension of the authors' previous study where the second beam was modeled as a semi-infinite beam. The second beam, which represents a train, moves with a constant speed along the bridge and is assumed to be connected to the bridge by the limiting case of a rigid interface such that the deflections of the bridge and the train are forced to be equal. The elastic stiffness and the mass of the train are taken into account. The differential equations are developed according to the Bernoulli-Euler theory and formulated in a non-dimensional form. A solution strategy is developed for the flexural vibrations, bending moments and shear forces in the bridge by means of symbolic computation. When the train travels across the bridge, concentrated forces and moments are found to take place at the front and back side of the train.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.461-464
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• 2000

A branched crack in a semi-infinite plate under tension and bending moment is considered. Intensity factors of the stress and moment for the branched crack are evaluated. The stress intensity factors are obtained by using the finite element method and the J-based mutual integral. The moment intensity factors are calculated by extrapolating the values of the moment near the crack tip. Approximate expressions are also obtained as functions of the branched crack length and branching angle.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.2
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• pp.60-66
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• 1994

The scattering problem by E-polarized plane wave with oblique incidence on a tapered resistive strip grating with infinite resistivity at strip-edges is analyzed by the method of moments in the spectral domain. Then the induced surface current density is expanded in a series of Ultraspherical polynomials of the zeroth order. The expansion coefficients are calculated numerically in the spectral domain, the numerical results of the geometricoptical reflection coefficient for the tapered resistivity in this paper are compared with those for the existing uniform resistivity. And the position of sharp variation points in the magnitude of the geometric-optical reflection coefficient can be moved by varying the incident angle and the strip spacing. It is found out that these sharp variation points are due to the transition of higher modes between the propagation mode and the evanescent mode.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.378-382
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• 2007

To improve the reliability for a wind-turbine gearbox, the mechanical loads acting on the gearbox need to be monitored and analysed exactly. This study was conducted to identify the characteristics of torques and bending moments acting on the main shaft of the gearbox using the rainflow counting method and predict the fatigue life of the main shaft by using the modified Miner's rule. While the mean wind speed became 3.5 m/s, the life of the main shaft by the acting torques was predicted as 4.3${\times}10^6$ years, and it by the bending moments was as 2.3${\times}10^4$ years. If the life of the wind turbine was estimated as 20 years, the fatigue life of the main shaft was regarded as infinite. Also, it was suggested that the life of the main shaft must be predicted by not the torques but the bending moments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.5
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• pp.395-407
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• 1996

In this paper, we describe the crossover of the parasitic capacitance at the interconnections for the system miniature, analyse ground capacitance and mutual capacitance due to actually coupled line in the ICs or MCMs. From the results of deviding interconnection line with infinite parts, using Green's function with image charge method and moments, we could obtain 70% decrease of system runtime parasitic inductance because of simplicity of transforming formular.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.8
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• pp.1187-1196
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• 1989

In this paper, a method for computing the capacitance parameter for a multi-interconnection line in a multilayered dielectric region is presented. The number of interconnection lines and the number of dielectric layers are arbitrary, and the interconnection lines are finite cross section or infinite cross section. The surface of lines and dielectric interface are divided into subsection. The surface charge density of each subsection is a constant step-pulse function for each subsection. After the solution of surface charge density is effected by the method of moments, capacitance parameter is calculated.