• Nuclear Engineering and Technology
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• v.38 no.3
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• pp.225-230
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• 2006

With the advent of inexpensive computing power over the past two decades, applications of Monte Carlo radiation transport techniques have proliferated dramatically. At Los Alamos, the Monte Carlo codes MCNP5 and MCNPX are used routinely on personal computer platforms for radiation shielding analysis and dosimetry calculations. These codes feature a rich palette of variance reduction (VR) techniques. The motivation of VR is to exchange user efficiency for computational efficiency. It has been said that a few hours of user time often reduces computational time by several orders of magnitude. Unfortunately, user time can stretch into the many hours as most VR techniques require significant user experience and intervention for proper optimization. It is the purpose of this paper to outline VR strategies, tested in practice, optimized for several common radiation shielding tasks, with the hope of reducing user setup time for similar problems. A strategy is defined in this context to mean a collection of MCNP radiation transport physics options and VR techniques that work synergistically to optimize a particular shielding task. Examples are offered in the areas of source definition, skyshine, streaming, and transmission.

• Journal of the Korean Data and Information Science Society
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• v.25 no.3
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• pp.547-554
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• 2014

This paper discusses a method of estimating variance components for random effects model. Henderson's method I and III are discussed for the esimation of variance components. This paper shows how to use projections instead of using Henderson's methods for the calculation of sums of squares which are quadratic forms in the observations. It also discusses that eigenvalues can be used for getting the expectations of sums of squares in place of using the method of Hartley's synthesis. It shows the suggested method is much more effective than those methods.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.12
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• pp.1217-1223
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• 2008

Vehicle vibration mostly originates from the road excitation and causes discomfort, fatigue and even injury to a driver. Vehicle ride comfort is one of the most important performance indices to achieve a high-quality vehicle design. Since design parameter variations inevitably result in the vehicle ride comfort variance, the variance characteristics should be analyzed in the early design stage of the vehicle. The vehicle ride comfort is often defined by an index which employs a weighted RMS value of the acceleration PSD of a seat position. The design solution is obtained through two steps in this study. An optimization problem to obtain a minimum ride comfort index is solved first. Then another optimization problem to obtain minimum variance of the ride comfort index is solved. For the optimization problems, the equations of motion and the sensitivity equations are derived basing on a 5-DOF vehicle model. The numerical results show that an optimal solution for the minimum ride comfort is not necessarily same as that of the minimum variance of the ride comfort.

• Journal of Life Science
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• v.14 no.3
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• pp.400-405
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• 2004

Morphological characteristics of Kalopanox pictus Nakai were studied to examine population differentiation of this species. Based on a phenogram of using 23 morphological characteristics, differentiation of regions were distinct. Collections of 138 specimens from nine populations served as operational taxonomic unit (OTU's) were examined for phenotypic similarity and morphological variation using clustering (Ward's minimum variance method) and principal component analysis (PCA). The first three principal components were responsible for 77.0% of the total variance. Principal component 1 explained 52% of the total variance and was contributed to by the number of palmately parted, the number of pinnately lobed, and width between two lateral lobe apex.

• Women's Health Nursing
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• v.14 no.1
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• pp.56-65
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• 2008

Purpose: The study was to develop an instrument to measure grandmothering stress for Korean day-care grandmothers and to test the validity and reliability of the instrument Method: The items of the instrument were based on a literature review and secondary data, After content validity tests and a pilot test, 20 items were developed. In order to test the reliability and validity of the scale, data were collected from 126 grandmothers. Result: After a factor analysis, five factors and 15 items were selected. These explained 67.2% of the total variance. The first domain was termed 'Health problems', and explained 18.1 % of the total variance, and the second domain of 'Possibility of role substitution' explained 13.8%. The third and the fourth domains were 'Relations with adult children' and 'Grandchildren's characteristics' explaining 12.5% and 12.1 %, respectively. The last domain explained 10.8% of the total variance with the theme 'Restriction of social life' After accomplishing the reliability analysis, Cronbach's alpha coefficient was determined to be .75. Conclusions : This initial step in the development of a Grandmothering Stress Index is valuable to reflect the subject of Grandmothering stress in senior citizens in Korea. Future study should to refine the constitution of the instrument.

• Journal of the Korean Society of Clothing and Textiles
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• v.14 no.4 s.36
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• pp.245-251
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• 1990

The purposes of the study were to efplain the independent influences of Asthetic Expression and Fashion on aesthetic evaluation in the clothing, to examine which in more important aesthetic components such as line/style, color, textile and detail in aesthetic evaluation in the clothing. Data were obtained from 221 female students living in Seoul area by eight photo-graphs of clothed bodies and a questionnaire. The data were analysied by Pearson's correlation, Analysis of valiables, scheffe-test and Regression analysis. The results of the study were as follows; 1. In the aesthetic evaluation of clothing, the $59.30\%$ of the total variance was explained by Aesthetic Expression, the $20.91\%$ of the total variance was explained by Fashion and $59.68\%$ of the total variance were explained by Aesthetic Expression and Fashion. More important variable of aesthetic evaluation was found to be an Aesthetic Expression. 2. Among aesthetic components such as line/style, color, textile and detail in aesthetic evaluation of the clothing, such general aspects as color and line/style were perceived at first and then specific ones like textile and detail.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.2307-2310
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• 2003

In this paper, a method for face recognition based on the wavelet packet decomposition is proposed. In the proposed method, the input image is decomposed by the 2-level wavelet packet transformation and then the face areas are defined by the Integral Projection technique applied to each of the 1-level subband images, HL and LH. After the defined face areas are divided into three areas, called top, bottom, and border, the mean and the variance of the three areas of the approximation image are computed, and the variance of the single predetermined face area for the rest of 15 detail images, from which the feature vectors of statistical measure are extracted. In this paper we use the wavelet packet decomposition, a generalization of the classical wavelet decomposition, to obtain its richer signal analysis features such as discontinuity in higher derivatives, self-similarity, etc. And we have shown that even with very simple statistical features such as mean values and variance we can make an excellent basis for face classification, if an appropriate probability distance is used.

• Communications for Statistical Applications and Methods
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• v.9 no.3
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• pp.835-844
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• 2002

For the one-way random model when the ratio of the variance components is of interest, Bayesian analysis is often appropriate. In this paper, we develop the noninformative priors for the ratio of the variance components under the balanced one-way random effect model. We reveal that the second order matching prior matches alternative coverage probabilities up to the second order (Mukerjee and Reid, 1999) and is a HPD(Highest Posterior Density) matching prior. It turns out that among all of the reference priors, the only one reference prior (one-at-a-time reference prior) satisfies a second order matching criterion. Finally we show that one-at-a-time reference prior produces confidence sets with expected length shorter than the other reference priors and Cox and Reid (1987) adjustment.

• Nuclear Engineering and Technology
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• v.31 no.3
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• pp.257-266
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• 1999

A simplified statistical methodology is developed in order to both reduce over-conservatism of deterministic methodologies employed for PWR fuel rod internal pressure (RIP) calculation and simplify the complicated calculation procedure of the widely used statistical methodology which employs the response surface method and Monte Carlo simulation. The simplified statistical methodology employs the system moment method with a deterministic approach in determining the maximum variance of RIP The maximum RIP variance is determined with the square sum of each maximum value of a mean RIP value times a RIP sensitivity factor for all input variables considered. This approach makes this simplified statistical methodology much more efficient in the routine reload core design analysis since it eliminates the numerous calculations required for the power history-dependent RIP variance determination. This simplified statistical methodology is shown to be more conservative in generating RIP distribution than the widely used statistical methodology. Comparison of the significances of each input variable to RIP indicates that fission gas release model is the most significant input variable.

• Phonetics and Speech Sciences
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• v.11 no.3
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• pp.23-29
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• 2019

This study acoustically examines the quality of fricatives produced by ten dysarthric speakers with cerebral palsy. Previous similar studies tend to focus only on sibilants, but to obtain a better understanding of how dysarthria affects fricatives we selected a range of samples with different places of articulation and voicing. The Universal Access (UA) Speech database was used to select thirteen words beginning with one of the English fricatives (/f/, /v/, /s/, /z/, /ʃ/, /ð/). The following four measurements were taken for both dysarthric and healthy speakers: phoneme duration, mean spectral peak, variance and skewness. Results show that even speakers with mild dysarthria have significantly longer fricatives and a lower mean spectral peak than healthy speakers. Furthermore, mean spectral peak and variance showed significant group effects for both healthy and dysarthric speakers. Mean spectral peak and variance was also useful for discriminating several places of articulation for both groups. Lastly, spectral measurements displayed important group differences when taking severity into account. These findings show that in general there is a degradation in the production of fricatives for dysarthric speakers, but difference will depend on the severity of dysarthria along with the type of measurement taken.