• 대한전기학회논문지:시스템및제어부문D
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• 제50권12호
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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.

• 한국운동역학회지
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• 제20권4호
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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.

• 한국통신학회논문지
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• 제21권10호
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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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• 제9권1호
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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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• 제1권1호
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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.

• 한국전자파학회논문지
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• 제7권4호
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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.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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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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• 제22권1호
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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.

• 한국수산과학회지
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• 제27권6호
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• pp.782-786
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• 1994

Dey and Morrison (1979)이 육상의 전기탐사문제의 해결에 성공적으로 적용한 적분차분법(integral finite different method)의 해양에서의 응용성을 연구해보기 위해, 해석해가 존재하는 연안역의 해수고유진동 문제를 도출하여 기존의 고유진동문제에 적용하여 보았다. 그 응용성의 평가는 기존 해양에 널리 적용되는 기존차분법(conventional finite different method)으로 구한 수치결과와 적분차분법으로 구한 결과를 해석해와의 비교검증을 통하여 실시되었다. 그 결과 적분차분법으로 구한 고유치와 고유함수값이 기존차분법으로 구한 결과보다 좋은것으로 나타났다. 이러한 결과는 적분차분법의 경우 원래의 기본방정식에 Green's theorem을 적용함으로써, 기본방정식에 존재하는 2계 미분연산자가 1계 미분연산자로 해석적으로 처리되었기 때문으로 사료된다. 따라서 적분차분법을 이용하여 해수고유진동문제를 비롯한 다른 유사문제를 풀 경우 기본차분법보다 좋은 결과가 나을 것으로 사료된다. 또한 미분방정식의 수치해를 구할 경우 적분법이 차분법보다 좋은해를 줄 수 있다는 것을 증명한 것으로 사료된다.

• 제어로봇시스템학회논문지
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• 제16권12호
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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.