• Journal of Nutrition and Health
• /
• v.26 no.8
• /
• pp.942-952
• /
• 1993

This study was to investigate if Body Mass Index(BMI) is adequate as a method of physique classification of Korean female college students. For this study 571 students were selected to examine physique classification by anthropometric index, and the correlation between the various anthropometric index and risk facters(blood pressure, triglyceride, hematocrit). The following results were obtained by this study. 1) Average age of the subjects is 19.6, height 158.2cm and weight 54.4g. 2) All anthropometric indices and body fat percentage are highly correlated (r>0.713), among them BMI shows high and significant positive correlation with weight(r=0.919) and skinfold thickness(r>0.601), but negative correlation with height(r=-0.086). 3) All anthropometric indices and body fat percentage show significant correlation with blood pressure and triglyceride. Among them BMI shows high and significant positive correlation with blood pressure and triglyceride. 4) FAT% III calculated of BMI shows significant with FAT% I and FAT% II by skinfold thickness, and high correlation with blood pressure and triglyceride. Therefore FAT% III is adequate for calculation method of body fat percentage.

• Journal of Institute of Control, Robotics and Systems
• /
• v.17 no.9
• /
• pp.875-881
• /
• 2011

This paper describes a new method of estimating the gradient of a function with perturbation and correlation. We impose a known periodic perturbation to the input variable and observe the output of the function in order to obtain much richer and more reliable information. By taking the correlation between the input perturbation and the resultant function outputs, we can determine the gradient of the function. The computation of the correlation does not require derivatives; therefore the gradient can be estimated reliably. Robust estimation of the gradient using perturbation/correlation, which is very effective when an analytical solution is not available, is described. To verify the effectiveness of perturbation/correlation based estimation, the results of gradient estimation are compared with the analytical solutions of an example function. The effects of amplitude of the perturbation and number of samplings in a period are investigated. A minimization of a function with the gradient estimation method is performed.

• Journal of Communications and Networks
• /
• v.7 no.3
• /
• pp.258-262
• /
• 2005

An adaptive beamforming system based on code filtering and differential correlation approaches is proposed. The differential correlation method was originally proposed for time delay estimation of direct sequence code division multiple access (DS-CDMA) systems under near-far ratio conditions and the code filtering correlation algorithm, on the other hand, was proposed for array response estimation in DS-CDMA systems under perfect power control. In this paper, by combining differential correlation concept with the code filtering beamforming technology, an accurate estimate of the beam forming weights and an enhanced performance of DS-CDMA systems under sever near-far ratio conditions is achieved. The system performance in terms of beam pattern and bit-error-rate (HER) shows that the proposed adaptive beamformer outperforms the conventional code filtering correlation technique.

• 한국가시화정보학회:학술대회논문집
• /
• 2001.12a
• /
• pp.75-85
• /
• 2001

The hierarchic recursive local-correlation PIV algorithm with CBC(correlation based correction) method was developed to increase the spatial resolution of PIV results and to reduce error vectors. This new algorithm was applied to the single-frame and double-frame cross-correlation PIV techniques. In order to evaluate its performance, the recursive algorithm was tested using synthetic images, PIV standard images from Visualization Society of Japan, real flows including ventilation flow inside a vehicle passenger compartment and wake behind a circular cylinder with rib let surface. As a result, most spurious vectors were suppressed by employing CBC method. In addition, the hierarchical recursive correlation algorithm improved largely the sub-pixel accuracy of PIV results by decreasing the interrogation window size, increasing spatial resolution significantly.

• Bulletin of the Korean Chemical Society
• /
• v.22 no.8
• /
• pp.807-815
• /
• 2001

Two-dimensional (2D) correlation method, which generates the synchronous and the asynchronous 2D spectrum by complex cross correlation of the Fourier transformed spectra, is an analysis method for the changes of the sample spectrum induced by vari ous perturbations. In the present work, the 2D electronic correlation spectra have been simulated for the cases where the sample spectrum composed of two gaussian bands changes linearly. When only the band amplitudes of the sample spectrum change, the synchronous spectrum shows strong peaks at the band centers of the sample spectrum, but the asynchronous spectrum does not make peaks. When the sample spectrum shifts without changing intensity and width, the synchronous spectrum shows peaks around the initial and final positions of the band maximum and the asynchronous spectrum shows long peaks spanning the shifting range. The band width change produces the complex 2D correlation spectra. When the sample spectrum shifts with band broadening, the width change by 50% of full width at half maximum (FWHM) does not give so large an effect on the correlation spectrum as the spectral shift by one half of FWHM of the sample spectrum.

• Journal of the Korean Data and Information Science Society
• /
• v.24 no.3
• /
• pp.651-658
• /
• 2013

For the marginal model and generalized estimating equations (GEE) method there is important full covariates conditional mean (FCCM) assumption which is pointed out by Pepe and Anderson (1994). With longitudinal data with time-varying stochastic covariates, this assumption may not necessarily hold. If this assumption is violated, the biased estimates of regression coefficients may result. But if a diagonal working correlation matrix is used, irrespective of whether the assumption is violated, the resulting estimates are (nearly) unbiased (Pan et al., 2000).The quadratic inference functions (QIF) method proposed by Qu et al. (2000) is the method based on generalized method of moment (GMM) using GEE. The QIF yields a substantial improvement in efficiency for the estimator of ${\beta}$ when the working correlation is misspecified, and equal efficiency to the GEE when the working correlation is correct (Qu et al., 2000).In this paper, we interest in whether the QIF can improve the results of the GEE method in the case of FCCM is violated. We show that the QIF with exchangeable and AR(1) working correlation matrix cannot be consistent and asymptotically normal in this case. Also it may not be efficient than GEE with independence working correlation. Our simulation studies verify the result.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.20 no.4
• /
• pp.548-553
• /
• 2010

This paper presents an effective shape image recognition method using the correlation based on 4-dimensional histogram. The histogram-based correlation is accurately applied to express the similarity by comparing the positions of a corresponding dimension between the images, which is calculated by considering 4 directions of the shape image. The correlation measure by using the normalized cross-correlation is also applied to obtain the robust recognition to the geometrical variations such as shape, position, size, and rotation. The proposed method has been applied to the problem for recognizing the 8 shape images of 64*64 pixels and the 30 shape images of 256*256 pixels. The experimental results show that the proposed method has a superior recognition performance that appears the image characters well.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.1903-1906
• /
• 2005

We proposed a new variant of correlation approach for ARMA model. The proposed method is is intended to make the current prediction error uncorrelated with the past one. In the investigation of the properties, the uniqueness, consistency and asymptotic normality of the estimate are shown. Via simulation results, we show that the proposed method give good estimates for various systems.

• Proceedings of the IEEK Conference
• /
• 1998.06a
• /
• pp.669-672
• /
• 1998

In this paper, w epropose a fast fractal coding method based on correlation coefficients of subblocks in input image. In the proposed method, domain pool is selected based on correlation analysis of input image and the isometry transform for each block is chosen based on the IFS method. To investigate the performance of the proposed method, we compared image quality and encoding time with full search PIFS method and jacquin's PIFS method. Experimental results show that proposed method yields nearly the same performance in PSNR, and its encoding time is reduced for images size of 512*512 compared with full search PIFS method and jacquin's PIFS method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.29 no.7
• /
• pp.491-499
• /
• 2018

The conventional calibration method for a noise figure analyzer is to use a noise source. This method is accompanied by a significant irregular ripple in the measurement results, because it does not consider the mismatch of the noise source and noise figure analyzer during calibration. A novel calibration method of the noise figure analyzer is proposed that considers the mismatch between the noise power and noise figure analyzer. A novel noise correlation matrix measurement technique using this method is also proposed. The method determines the noise correlation matrix and the gain of the uncorrected noise figure analyzer using uncorrected noise powers. Then, having determined the gain and noise correlation matrix, the effects of noise figure analyzers were corrected in the measurement results of the noise correlation matrix for the device under test (DUT). Through the proposed method, the measured noise parameters of a DUT showed the same degree of irregular ripples as the result of using the relative noise ratio.