• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.2
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• pp.318-329
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• 1994

This paper deals with the finite wordlength effect on the performance of digital PID controllers. The finite wordlength, one of the major limitation factors in digital controllers, results on two kinds of quantization error : the signal quantization error and the coefficient quantization error. This paper derives the variance of the plant output due to the signal quantization error. Using stability margins as performance criterion, the statistical wordlength concept is adopted for coefficient wordlength selection. Finally, the experimental results exhibit satisfactory performance of the digital PID controller with statistical coefficient wordlength.

• Korean Journal of Adult Nursing
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• v.20 no.3
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• pp.470-480
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• 2008

Purpose: The purpose of this study was to validate the scale of Informatics Competencies for Nurses developed by Staggers, Gassert & Curran(2001) among Korean nurses. Methods: The subjects of this study were 58 RN-BSN students and 314 nurses in Busan, Ulsan and Kyoungnam province. Data were collected by questionnaires from June to August, 2006 and from October, 2006 to August, 2007 and were analyzed by Principal Component Analysis for construct validity and Cronbach's ${\alpha}$ coefficient for reliability. Results: A factor analysis was conducted and 30 items that had a factor loading more than .40 were extracted. The explained variance from 5 factors was 55.33% of the total variance. The factors were named 'basic computer usage', 'medical informatics-related software usage', 'computer related information management', 'perception of informatics', and 'information search using internet'. The first factor consisted 10 items which explained 29.89% of the total variance and the second factor contained 7 items. The Cronbach's ${\alpha}$ coefficient was .91 among the 30 items. Conclusion: This scale, Informatics Competencies for Nurses, was proved as a proper instrument to apply to Korean nurses.

• Communications for Statistical Applications and Methods
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• v.27 no.5
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• pp.523-533
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• 2020

This paper suggests three available methods for finding nonnegative estimates of variance components of the random effects in mixed models. The three proposed methods based on the concepts of projections are called projection method I, II, and III. Each method derives sums of squares uniquely based on its own method of projections. All the sums of squares in quadratic forms are calculated as the squared lengths of projections of an observation vector; therefore, there is discussion on the decomposition of the observation vector into the sum of orthogonal projections for establishing a projection model. The projection model in matrix form is constructed by ascertaining the orthogonal projections defined on vector subspaces. Nonnegative estimates are then obtained by the projection model where all the coefficient matrices of the effects in the model are orthogonal to each other. Each method provides its own system of linear equations in a different way for the estimation of variance components; however, the estimates are given as the same regardless of the methods, whichever is used. Hartley's synthesis is used as a method for finding the coefficients of variance components.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.1
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• pp.57-66
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• 2007

Scanning worms increase network traffic load because they randomly scan network addresses to find hosts that are susceptible to infection. Since propagation speed is faster than human reaction, scanning worms cause severe network congestion. So we need to build an early detection system which can automatically detect and quarantine such attacks. We propose algorithms to detect scanning worms using network traffic characteristics such as variance, variance to mean ratio(VMR) and correlation coefficient. The proposed algorithm have been verified by computer simulation. Compared to existing algorithm, the proposed algorithm not only reduced computational complexity but also improved detection accuracy.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.12
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• pp.1686-1689
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• 2002

Genetic gains and inbreeding coefficients in a Holstein MOET breeding population were predicted under different conditions relating to the distribution of the number of transferable embryos collected per flush using Monte Carlo simulation. The numbers of transferable embryos collected per flush were determined using five distributions (distributions 1, 3, 5, 7 and 9) with different aspects and similar means. Distributions 1, 3, 5, 7 and 9 were assumed to have gamma distribution's parameters ($\alpha$ and $\beta$) of (1 and 4.4), (3 and 1.47), (5 and 0.88), (7 and 0.63) and (9 and 0.49), respectively. Inbreeding rates were statistically significantly different among distributions but genetic gains were not. Relationships between inbreeding rates and variances of family size could be were clearly distinguished. The highest inbreeding coefficients were predicted in distribution 1 with the largest variance of family size, while distributions 5, 7 and 9 with smaller variance of family size had lower inbreeding coefficients.

• Journal of the Korea Society for Simulation
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• v.14 no.4
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• pp.9-18
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• 2005

In this paper, the system is implemented in four ways , For those who want to learn Chinese characters using the internet, and To make the learning more interesting and entertaining. Four different learning methods have been provided , using the transition process of Chinese characters, games, animations, and an illustration of the relationships between Chinese Characters and korean letters. The subjects of the evaluation were freshmen polled about the Chinese character learning system. The evaluation methods are : the validity of the research content is evaluated using the Cronbach's coefficient alpha and the performance of the system is evaluated by F-type of Analysis of variance.

• Proceedings of the Safety Management and Science Conference
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• 2008.11a
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• pp.353-359
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• 2008

Somatotype is a very important factor for the comfortable and safe work environments. Many researches are trying to find the characteristics of somatotype according to age. Thus, the main objective of this study is to analyze somatotype of male residents in Seoul. The data used in this study included 267 men subjects who are living in Seoul. In order to analyze a detailed somatotype of citizens, age groups are divided into six groups. In order to compare and analyze data, Coefficient of Variance, Cronbach's Alpha, $R\ddot{o}hrer$ Index and Drop Value were used in this study. The results of this study can be applied to the comfortable and safe work environments for workers.

• Korean Journal of Food Science and Technology
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• v.26 no.1
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• pp.57-61
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• 1994

Performance of panelists trained for cooked rice quality was evaluated using analysis of variance, correlation analysis, and principal component analysis. Each method offered different information. Results showed that panleists with high F ratios (p=0.05) did not always have high correlation coefficient (p=0.05) with mean values pooled from whole panel. The results of analysis of variance for the panelists whose performance were extremely good or extremely poor were consistent with those of correlation analysis. Outliers designated by principal component analysis were different from the panelists whose performance was defined as extremely good or extremely poor by analysis of variance and correlation analysis. The results of principal component analysis descriminated the panelists with different scoring range more than different scoring trends depending on the treatments. Our study suggested combination of analysis of variance and correlation analysis provided valid basis for screening panelists.

• Journal of the Korean Statistical Society
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• v.29 no.1
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• pp.81-94
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• 2000

For the balanced variance component model, sometimes intraclass correlation coefficient is of interest. If there is little information about the parameter, then the reference prior(Berger and Bernardo, 1992) is widely used. Pettit nd Young(1990) considered a measrue of the effect of a single observation on a logarithmic Bayes factor. However, under such a reference prior, the Bayes factor depends on the ratio of unspecified constants. In order to discard this problem, influence diagnostic measures using the intrinsic Bayes factor(Berger and Pericchi, 1996) is presented. Finally, one simulated dataset is provided which illustrates the methodology with appropriate simulation based computational formulas. In order to overcome the difficult Bayesian computation, MCMC methods, such as Gibbs sampler(Gelfand and Smith, 1990) and Metropolis algorithm, are empolyed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.6
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• pp.510-520
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• 1988

In this paper, the output error variance due to the differential vcariation of the state-space coefficient [ABCD], which is the coefficient quentization error, is normalized on the variance for cases that infinite wordlength state-space digital filter is realized by the finite one. That is, defining S as the statistical sensitivity and extending controllability gramian, observability gramian, and 2nd order mode analysis method to the state space digital filter, we synthesize the realization structure with the minimum statistical sensitivity and prove the effecency of the minimum statistical sensitivity structure synthesis by the simulation.