• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.3 s.246
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• pp.310-317
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• 2006

Currently most practical vibration and structural problems in automotive suspensions require the use of the finite element method to obtain their structural responses. When the finite element model has a very large number of degrees of freedom the harmonic and dynamic analyses are computationally too expensive to repeat within a feasible design process time. To alleviate the computational difficulty, this paper presents a moment-matching based model order reduction (MOR) which reduces the number of degrees of freedom of the original finite element model and speeds up the necessary simulations with the reduced-size models. The moment-matching model reduction via the Arnoldi process is performed directly to ANSYS finite element models by software mor4ansys. Among automotive suspension components, a knuckle is taken as an example to demonstrate the advantages of this approach for vibration simulation. The frequency and transient dynamic responses by the MOR are compared with those by the mode superposition method.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.5 no.4
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• pp.30-39
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• 1994

The resonant frequency, reflection cofficient and input impedance of a microstrip transverse dipole coupled electromagnetically are calculated using Finite Difference Time Domain(FDTD) method, and the evolution of gaussian pulse and spatial distribution of electromagnetic field components in the computation domain is represented graphically. Also, we confirmed the computation results show good agreement with the results of Method of Moment(MOM) and experiment[8] reported in the literature.

• Journal of the Korea Concrete Institute
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• v.26 no.2
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• pp.159-169
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• 2014

This study generalizes the lateral load-displacement relationship of reinforced concrete shear walls from the section analysis for moment-curvature response to straightforwardly evaluate the flexural capacity and ductility of such members. Moment and curvature at different selected points including the first flexural crack, yielding of tensile reinforcing bar, maximum strength, 80% of the maximum strength at descending branch, and fracture of tensile reinforcing bar are calculated based on the strain compatibility and equilibrium of internal forces. The strain at extreme compressive fiber to determine the curvature at the descending branch is formulated as a function of reduction factor of maximum stress of concrete and volumetric index of lateral reinforcement using the stress-strain model of confined concrete proposed by Razvi and Saatcioglu. The moment prediction models are simply formulated as a function of tensile reinforcement index, vertical reinforcement index, and axial load index from an extensive parametric study. Lateral displacement is calculated by using the moment area method of idealized curvature distribution along the wall height. The generalized lateral load-displacement relationship is in good agreement with test result, even at the descending branch after ultimate strength of shear walls.

• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.403-409
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• 1997

The equilibrium constants of five deoxyribonucleosides (dDyd, dUrd, dGuo, dThd, dAdo) were estimated by the plate theory and the moment method under isocratic conditions of the Reversed-Phase High Performance Liquid Chromatography (RP-HPLC). The mobile phase in this system was composed of water and organic modifiers(acetonitrile and methanol) The plate theory of linear adsorption isotherm was treated on the basis of continuous flow of eluent through the plates of the column. The moment method was utilized to find the equilibrium constant from the first absolute moment of experimental data. The equilibrium constants of five deoxyribonucleosides in the two methods were very close, and also the equilibrium constants calculated by capacity factor were similar to those by both the plate theory and the moment method. The equilibrium constant was expressed as a semi-log function of the quantity of organic modifier. Excellent agreements between the calculated elusion profile by the plate theory and the experimental data were observed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.9
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• pp.878-885
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• 2009

One of important factors in designing MEMS resonators for RF filters is obtaining a desired frequency response function (FRF) within a specific frequency range of interest. Because various array-type MEMS resonators have been recently introduced to improve the filter characteristics such as bandwidth, pass-band, and shape factor, the degrees of freedom (DOF) of finite elements for their FRF calculation dramatically increases and therefore raises computational difficulties. In this paper the Krylov subspace-based model order reduction using moment-matching with non-zero expansion points is represented as a numerical solution to perform the frequency response analyses of those array-type MEMS resonators in an efficient way. By matching moments at a frequency around the specific operation range of the array-type resonators, the required FRF can be efficiently calculated regardless of their operating frequency from significantly reduced systems. In addition, because of the characteristics of the moment-matching method, a minimal order of reduced system with a prearranged accuracy can be determined through an error indicator using successive reduced models, which is very useful to automate the order reduction process and FRF calculation for structural optimization iterations. We also found out that the presented method could obtain the FRF of a $6\times6$ array-type resonator within a seventieth of the computational time necessary for the direct method and in addition FRF calculation by the mode superposition method could not even be completed because of a data overflow with a half after calculation of 9,722 eigenmodes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.6
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• pp.699-712
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• 1989

This paper describes a method of Korean speech synhes is using format VOCODER. The parameters of speech synthes is are a follows, 1) format F1, F2, and F3 by spectrum moment method and F4, F5 using the length of vocal tract. 2) pitch frequencies obtained by optimu, Comb method using AMDF. 3) short time average energy and short time mean amplitude. 4) The decision method of bandwidth reportd by Fant. 5) voicde/unvoiced discrimination using zerocrossing. 6) excitation wave reported by Rosenberg. 7) gaussian white noise. Synthesis results are in fairly good agreement with original speech.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.5
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• pp.541-549
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• 2007

In the case of control for mechanical systems, it is highly useful to be able to provide a compact model of the mechanical system to control engineers using the smallest number of state variables, while still providing an accurate model. The reduced mechanical model can then be inserted into the complete system models and used for extended system-level dynamic simulation. In this paper, moment-matching based model order reductions (MOR) using Krylov subspaces, which reduce the number of degrees of freedom of an original finite element model via the Arnoldi process, are presented to study the eigenvalue and frequency response problems of a HDD actuator and suspension system.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.12
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• pp.566-574
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• 2002

In this paper, the scattered field from a perfectly conducting fractal surface by the Monte-Carlo moment method was computed. An one-dimensional fractal surface was generated by using the fractional Brownian motion model. Back scattering coefficients are calculated with different values of the spectral parameter(S$\_$0/), and fractal dimension(D) which determine characteristics of the fractal surface. The number of surface realization for the computed field, the point number, and the width of surface realization are set to be 80, 2048, and 64L, respectively. In order to verify the computed results these results are compared with those of small perturbation methods, which show good agreement between them.

• Journal of IKEEE
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• v.7 no.1 s.12
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• pp.32-42
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• 2003

In this paper, radiation pattern of rectangular microstrip patch antenna with anisotropy substrates and superstrate is studied by using a rigorous full-wave approach and a moment method calculation. Dyadic Green's function is derived for selected anisotropy material by constitutive relation. From these results, integral equations of electric fields are formulated. The electric field integral equations are discretized into the matrix form by applying Galerkin's moment method and then the current coefficients are obtained.. After solving the current coefficients, the far-zone electric field in spherical coordinates can be obtained by using the stationary phase method. To verify the validity of numerical result, we compare our result with existing one and get a good agreement between them. From the numerical results, the radiation patterns for variation of uniaxial superstrate thickness, anisotropy ratio of substrate and superstrate layer are presented and analyzed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.7
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• pp.973-984
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• 1999

This paper presents a method of moments with the transmission line theory to analyze the sleeve dipole array antennas and analyses characteristics of that. There were several considerations for analysis of the method of moments. First, the method of moments were applied at both of the sleeve dipole elements and the coaxial line because the current flows on both of them. Second, the feed voltages of each sleeve dipole element were obtained by using a transmission line theory because the feeding structure is fed by coaxial line in series. Third, the series reactance between the coaxial line and the open side of the sleeve was considered as impedance loading on the antenna. The radiation patterns and current distributions from the numerical results were considered as variation of the feed distances and frequencies. To verify the validity of our method, 4 elements sleeve dipole array antennas with 1 λg distance were fabricated and measured, and then the measured radiation patterns were compared with the numerical results. The measured results were confirmed a good agreement with the numerical results.