• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.12
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• pp.590-596
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• 2001

The pre-emphasis is an essential process for speech signal processing. Widely used two methods are the typical method using a fixed value near unity and te optimal method using the autocorrelation ratio of the signal. This study proposes a new pre-emphasis method using the short-term energy difference of speech signal, which can effectively compensate the glottal source characteristics and lip radiation characteristics. Using the proposed pre-emphasis, speech analysis, such as spectrum estimation, formant detection, is performed and the results are compared with those of the conventional two pre-emphasis methods. The speech analysis with 5 single vowels showed that the proposed method enhanced the spectral shapes and gave nearly constant formant frequencies and could escape the overlapping of adjacent two formants. comparison with FFT spectra had verified the above results and showed the accuracy of the proposed method. The computational complexity of the proposed method reduced to about 50% of the optimal method.

• Korean Journal of Applied Biomechanics
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• v.20 no.4
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• pp.421-427
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• 2010

The purpose of this study was to investigate the relationship between the quantitative analysis of biomechanical movement and the qualitative analysis of video software in order to evaluate for the walking movement. The fourteen collegiate students who agreed with the purpose and method of this study participated as subjects. The slow walking and fast walking of the subjects in the place of experiment were photographed, and calculated several mechanical factors. This empirical evidence from the experiment indicated the significant difference(p<.001) between each distant factors of the walking movement for both analyses methods, but there was no statistically significant difference between the spacial factors observed in the experiment. For more detail, no significant difference between the walking ratios that expressed the coordination between stride length and stride frequency was found. The findings also indicated the high coefficient of correlation(over r=.9) which supports higher explanation force for the biomechanical method and the Dartfish video software method. Therefore, if the data was gathered by using the proper experimental method, the video software method could be used just like the quantitative data of biomechanical method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.10
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• pp.2724-2730
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• 1996

In this paper, the dispersive characteristics of the Finite-Difference Frqequency-Domain method based on the Multi-Resolution Technique(MR-FDFD) are numerically analyzed. A dispersion analysis of the MR-FDFD ority of the MR-FDFD method to the spatial discretization is shown. We expect that the multi-resoluation technique will improve the disavantage of the finite difference techqnique which needs the large comutational memory for accurate electromagnetic analysis.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.9 no.1
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• pp.91-98
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• 2005

The straight rectangular fin is analyzed using the one-dimensional analytic method and the finite difference method. For the finite difference method, the numbers of nodes vary from 20 to 100. The relative errors of heat loss and temperature between the analytic method and the finite difference method are represented as a function of Biot Number and dimensionless fin length. One of the results shows that the relative error between the analytic method and the finite difference method decreases as the numbers of nodes for finite difference method increase.

• International Journal of Safety
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• v.1 no.1
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• pp.13-17
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• 2002

A new system of equations governing the nonlinear thin laminated plates with large deflections using von Karman equations is derived. The effects of transverse shear in the thin interlayer are included as part of the analysis. The finite difference method is used to perform the geometrically nonlinear behavior of the plate. The resultant equations permit the analysis of the effect of transverse shear stress deformation on the overall behavior of the interlayer using the load incremental method. For the purpose of feasibility and validity of this present method, the numerical results are compared with other available solutions for accuracy as well as efficiency. The solution techniques have been implemented and the numerical results of example problem are discussed and evaluated.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.4
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• pp.320-327
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• 1996

This paper presents that the lossy or amplification property of the Finite Difference-Time Domain(FD-TD) method based on the leap-frog scheme is theoretically verified by using a plane wave analysis. The basic algorithm of the FD-TD method is introduced in order to help understanding the analysis procedure. Since our analysis is formulated by the Von Neumann's approach, the stability inequality is also produced as an another outcome.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.920-924
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• 2002

This paper presents the reverse design of a cam mechanism using NURBS(Nonuniform Rational B-spline curve). Cam is very difficult to make the accurate shape on the design and the manufacture. Because the cam shape is commonly made in order to move in special functions. The reverse design can be used to check accuracy between the designed data and the manufactured data of the cam shape and also reproduce the cam without the design data. The reverse design procedures consist of motion analysis and curve fitting. The motion analysis is used the central difference method and the relative velocity method to find the displacement and velocity. The curve fitting is used NURBS to develope the whole curve. The central difference method is derived in the 3 dimensional space.

• Journal of Magnetics
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• v.22 no.1
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• pp.104-108
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• 2017

Induction motors have wide applicability in many fields, both in industrial sectors and households, for their advantages of a high efficiency and robust structure. The introduction of power-source-containing harmonics into the induction motor winding lowers its efficiency and increases its temperature, greatly affecting its operation characteristics. In this study, we performed an electromagnetic field analysis using the time-difference finite-element method with the purpose of analyzing the steady-state current characteristics of an induction motor. Additionally, we calculated the steady-state current with a method combining an electromagnetic field equation and a circuit equation. In the electromagnetic field analysis, the nonlinearity was taken into account using the Newton-Raphson method, and a backward time-difference method was employed for the time derivative term. Then, we compared the steady-state current of the induction motor obtained by calculation with the experimentally measured values, thus validating the proposed algorithm. Furthermore, we analyzed the impacts of the shape and material of the rotor conductor bar of the induction motor on the steady-state current of the main winding.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.6
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• pp.782-786
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• 1994

Integrated finite difference method (IFDM) is used to solve one dimensional free oscillation problem in the coastal area. To evaluate the solution accuracy of IFDM in free oscillation analysis, two finite difference equations based on area discretization method and point discretization method are derived from the governing equations of free oscillation, respectively. The difference equations are transformed into a generalized eigenvalue problem, respectively. A numerical example is presented, for which the analytical solution is available, for comparing IFDM to conventional finite difference equation (CFDM), qualitatively. The eigenvalue matrices are solved by sub-space iteration method. The numerical results of the two methods are in good agreement with analytical ones, however, IFDM yields better solution than CFDM in lower modes because IFDM only includes first order differential operator in finite difference equation by Green's theorem. From these results, it is concluded that IFDM is useful for the free oscillation analysis in the coastal area.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.12
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• pp.1176-1181
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• 2010

This paper proposes three positioning algorithms using TOA measurements: 1) The well-known linearization method using Taylor series, 2) a modified Savarese method considering measurement noise, which does not need linearization, and 3) a modified Bancroft method where TOA measurements instead of pseudorange measurements are considered. Furthermore, through an error analysis, for Savarese method, divergence of altitude is anticipated if the transmitters are located at the same height. To prevent height divergence, the Savarese method is modified again for receivers which assumed moving on the even plane. Error analysis also shows the relationship between Bancroft and Savarese method. From the analysis it is expected that the performance of Savarese method is worse than Bancroft method because of error amplification during difference operation. Experiments using real TOA measurement from the time difference of ultra sound and RF validate the proposed methods and show that analysis is correct.