• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.1
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• pp.1-9
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• 1999

For roughened annular pipes with diameter ratios of 0.26, 0.39, and 0.56 and with Reynolds numbers ranging 13,000 to 67,000, friction factor, autocorrelation coefficients, power spectral density functions, and integral length scales for each flow condition using X-type hot wire anemometry system are experimentally investigated. Distributions of these quantities show that the times which the streamwise autocorrelation coefficients become zero first increase with decreasing the radius ratios of concentric annuli and Reynolds numbers, however the power spectra density functions increase with increasing the radius ratios and Reynolds number.

• Journal of applied mathematics & informatics
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• v.18 no.1_2
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• pp.301-310
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• 2005

The coefficients of the Rudin-Shapiro polynomials are $\pm1$. In this paper we first replace-1 coefficient by 0 which on that case the structure of the coefficients will be on base 2. Then using the results obtained for the numbers on base 2, we introduce a quite fast algorithm to calculate the autocorrelation coefficients. Main facts: Regardless of frequencies, finding the autocorrelations of those polynomials on which their coefficients lie in the unit disk has been a telecommunication's demand. The Rudin-Shapiro polynomials have a very special form of coefficients that allow us to use 'Machine language' for evaluating these values.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.959-964
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• 2010

In this work, equilibrium molecular dynamics (MD) simulations in a microcanonical ensemble are performed to evaluate the friction coefficient of a Brownian particle (BP) in a Lennard-Jones (LJ) solvent. The friction coefficients are determined from the time dependent friction coefficients and the momentum autocorrelation functions of the BP with its infinite mass at various ratios of LJ size parameters of the BP and solvent, ${\sigma}_B/{\sigma}_s$. The determination of the friction coefficients from the decay rates of the momentum autocorrelation functions and from the slopes of the time dependent friction coefficients is difficult due to the fast decay rates of the correlation functions in the momentum-conserved MD simulation and due to the scaling of the slope as 1/N (N: the number of the solvent particle), respectively. On the other hand, the friction coefficient can be determined correctly from the time dependent friction coefficient by measuring the extrapolation of its long time decay to t=0 and also from the decay rate of the momentum autocorrelation function, which is obtained by time integration of the time dependent friction coefficient. It is found that while the friction coefficient increases quadratically with the ratio of ${\sigma}_B/{\sigma}_s$ for all ${\sigma}_B$, for a given ${\sigma}_s$ the friction coefficient increases linearly with ${\sigma}_B$.

• The Journal of the Acoustical Society of Korea
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• v.1 no.1
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• pp.45-53
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• 1982

A robust linear predictive coding method that can be used in noisy as well as quiet environment has been studied. In this method, noise autocorrelation coeffieients are first obtained and updated during nonspeech periods. Then, the effect of additive noise in the input speech is removed by subtracting values of the noise autocorrelation coefficients of corrupted speech in the course of computation of linear prediction coefficients. When signal-to-noise ratio of the input speech ranges from 0 to 10 dB, a performance improvement of about 5 dB can be gained by using this method. The proposed method is computationally very efficient and requires a small storage area.

• Journal of Korean Society of Disaster and Security
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• v.6 no.2
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• pp.49-56
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• 2013

In this paper, used by the boundary layer wind tunnel test, have conducted a series of wind tunnel experiments, i.e. test the mean velocity profile regarding the surface roughness, turbulence intensity and power spectrum measured by augmentation device. After that, to provide data relevant for the preliminary design step of tall building hazard fluctuating wind loads may be obtained fluctuating pressure coefficients, fluctuating pressure spectrum, autocorrelation coefficients by the boundary layer wind tunnel test. From the results of experiments, this study can be obtained conclusions as follows. 1. We know the fact that the mean velocity profile and the turbulence intensity are well fitted natural wind flow in the boundary layer wind tunnel. 2. The satisfactory agreement of velocity spectrum can be obtained from the compare of fluctuating power spectrum and Von Karman spectrum. 3. We know the fact that the fluctuating pressure spectrums distributed peak at 0.01 Hz-0.1 Hz in the windward surfaces and at 0.1 Hz in the leeward surfaces. 4. We know the fact that the autocorrelation coefficients distributed stationary random processes with application time of hazard fluctuating wind loads.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.75.5-75
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• 2002

$\textbullet$ FFT $\textbullet$ Autocorrelation $\textbullet$ Levinson_Durbin resolution $\textbullet$ LP coefficients $\textbullet$ LP cepstral Coefficients $\textbullet$ Incremental Learning

• Bulletin of the Korean Chemical Society
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• v.4 no.5
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• pp.223-227
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• 1983

A molecular dynamic computer experiment was performed on a system of 108 particles composed of a single polymer chain and solvent molecules. The state considered was in the immediate neighborhood of the triple point of the system. The polymer itself is an analog of a freely jointed chain. The Lennard-Jones potential was used to represent the interactions between all particles except for that between the chain elements forming a bond in the polymer chain, for which the interaction was expressed by a harmonic potential. The self-diffusion coefficient and velocity autocorrelation function (VACF) of a polymer were calculated at various chain lengths $N_p$, and various interaction strengths between solvent molecules and a polymer chain element. For self-diffusion coefficients D, the Einstein relation holds good; as chain length $N_p$ increases the D value decreases, and D also decreases as ${\varepsilon}_{cs}$ (the interaction parameter between the chain element and solvent molecules) increases. The relaxation time of velocity autocorrelation decreases as ${\varepsilon}_{cs}$ increases, and it is constant for various chain lengths. The diffusion coefficients in various conditions reveal that our systems are in a free draining limit as is well known from the behavior of low molecular weight polymers, this also agrees with the Kirkwood-Riesman theory.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.12
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• pp.120-128
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• 1996

An attempt is made to characterize and synthesize engineered surfaces. The proposed method is not only an analytical tool to characterize but also to generate/synthesize three-dimensional surfaces. The developed method expresses important engineered surface characteristics such as the autocorrelation or power spectrum density functions in terms of the two-dimensional autoregressive coefficients.

• Journal of applied mathematics & informatics
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• v.26 no.5_6
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• pp.973-981
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• 2008

In this paper we focus on a type of Unimodular polynomial pair used for digital systems and present some new properties of them which lead us to estimation of their autocorrelation coefficients and the moments of a Rudin-Shapiro polynomial product. Some new results on the Rudin-shapiro sequences will be presented in the last section. Main Facts: For positive integers M and n with $M\;<\;2^n$ - 1, consider the $2^n$ - M numbers ${\epsilon}_k$ ($M\;{\leq}\;k\;{\leq}\;2^n$ - 1) which form a collection of Rudin-Shapiro coefficients. We verify that $|{\sum}_{k=M}^{2^{n-1}}\;{{\epsilon}_k}e^{ikt}|$ is dominated by $(2+\sqrt{2})\;\sqrt {2^n-M}-{\sqrt{2}}$.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.41 no.2
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• pp.37-44
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• 2004

In this paper, we performed the design and the development of the wide-band correlation board to be an important role in the autocorrelation spectrometer's building for the observation study of an extra-galaxy's spectral lines and the survey research of the special radio sources in field of the radio astronomy. In this research, the developed correlation board by using QUAINT correlator chip(made by NRAO) has maximum 100 MHz clock speed and operate at a intermediate frequency with 400 MHz bandwidth. For the Performance test we supply the 0.5 and 1.67 MHz rectangular wave, then we obtain the autocorrelation coefficients. The final results, which process by using FFT, get the almost same results compare with the theoretical correlation.