• Asian-Australasian Journal of Animal Sciences
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• v.29 no.5
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• pp.607-614
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• 2016

The objectives of the study were to estimate genetic parameters for milk production traits of Holstein cattle using random regression models (RRMs), and to compare the goodness of fit of various RRMs with homogeneous and heterogeneous residual variances. A total of 126,980 test-day milk production records of the first parity Holstein cows between 2007 and 2014 from the Dairy Cattle Improvement Center of National Agricultural Cooperative Federation in South Korea were used. These records included milk yield (MILK), fat yield (FAT), protein yield (PROT), and solids-not-fat yield (SNF). The statistical models included random effects of genetic and permanent environments using Legendre polynomials (LP) of the third to fifth order (L3-L5), fixed effects of herd-test day, year-season at calving, and a fixed regression for the test-day record (third to fifth order). The residual variances in the models were either homogeneous (HOM) or heterogeneous (15 classes, HET15; 60 classes, HET60). A total of nine models (3 orders of $polynomials{\times}3$ types of residual variance) including L3-HOM, L3-HET15, L3-HET60, L4-HOM, L4-HET15, L4-HET60, L5-HOM, L5-HET15, and L5-HET60 were compared using Akaike information criteria (AIC) and/or Schwarz Bayesian information criteria (BIC) statistics to identify the model(s) of best fit for their respective traits. The lowest BIC value was observed for the models L5-HET15 (MILK; PROT; SNF) and L4-HET15 (FAT), which fit the best. In general, the BIC values of HET15 models for a particular polynomial order was lower than that of the HET60 model in most cases. This implies that the orders of LP and types of residual variances affect the goodness of models. Also, the heterogeneity of residual variances should be considered for the test-day analysis. The heritability estimates of from the best fitted models ranged from 0.08 to 0.15 for MILK, 0.06 to 0.14 for FAT, 0.08 to 0.12 for PROT, and 0.07 to 0.13 for SNF according to days in milk of first lactation. Genetic variances for studied traits tended to decrease during the earlier stages of lactation, which were followed by increases in the middle and decreases further at the end of lactation. With regards to the fitness of the models and the differential genetic parameters across the lactation stages, we could estimate genetic parameters more accurately from RRMs than from lactation models. Therefore, we suggest using RRMs in place of lactation models to make national dairy cattle genetic evaluations for milk production traits in Korea.

• Earthquakes and Structures
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• v.17 no.2
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• pp.143-162
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• 2019

Motivated by a simpler and more compact hybrid active tuned mass damper (ATMD) system with wide frequency spacing (i.e., high robustness) but not reducing the effectiveness using the least number of ATMD units, the active tuned tandem mass dampers (ATTMD) have been proposed to attenuate undesirable oscillations of structures under the ground acceleration. Likewise, it is expected that the frequency spacing of the ATTMD is comparable to that of the active multiple tuned mass dampers (AMTMD) or the multiple tuned mass dampers (MTMD). In accordance with the mode generalised system in the specific vibration mode being controlled (simply referred herein to as the structure), the closed-form expression of the dimensionless displacement variances has been derived for the structure with the attached ATTMD. The criterion for the optimum searching may then be determined as minimization of the dimensionless displacement variances. Employing the gradient-based optimization technique, the effects of varying key parameters on the performance of the ATTMD have been scrutinized in order to probe into its superiority. Meanwhile, for the purpose of a systematic comparison, the optimum results of two active tuned mass dampers (two ATMDs), two tuned mass dampers (two TMDs) without the linking damper, and the TTMD are included into consideration. Subsequent to work in the frequency domain, a real-time Simulink implementation of dynamic analysis of the structure with the ATTMD under earthquakes is carried out to verify the findings of effectiveness and stroke in the frequency domain. Results clearly show that the findings in the time domain support the ones in the frequency domain. The whole work demonstrates that ATTMD outperforms two ATMDs, two TMDs, and TTMD. Thereinto, a wide frequency spacing feature of the ATTMD is its highlight, thus deeming it a high robustness control device. Furthermore, the ATTMD system only needs the linking dashpot, thus embodying its simplicity.

• Journal of the Korean Society of Clothing and Textiles
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• v.26 no.5
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• pp.573-581
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• 2002

This study was done to classify children's somatotypes and to provide the fundamental data or their clothing sizing system for the purpose of designing patterns fur children's wear and standardizing sizes of ready-made clothes. The sampling was done for 7-8 years-old-girl living in Pusan and Kyungsangnam-do. Data from each girl comprises 33 anthropometic measurments and 7 photogrphic measurments, based on the somatometric characteristics of girls which I had obtained. Factor analysis, cluster analysis, discriminant analysis were performed for statistical analysis of the data. Seven factors which explain 76.49% of the whole variances were extracted. The thirst and second factors which explain more than 70% of the whole variances represent 'horizontal size 'and 'vortical size', which characterize most aspects of the body shape of the subjects. On the basis of the cluster analysis, three different upper body types were categorized. Type 1 has quite long surface length of the upper body and rising shoulders and are close to the averages of this age group. Type 2 has highest stature, biggest frame, dropped shoulders and surface length of the upper body similar to the type 1. Type 3 has shortest stature, smallest frame and sloping shoulders. According to the analysis to discriminate somatotypes of the upper body by this age group, the discriminative items in discriminant function are follows. As this group, waist circumference of discriminant function 1 and front length and length between both shoulder points of discriminant function 2 have large coefficient values.

• Journal of the Korean Data and Information Science Society
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• v.11 no.1
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• pp.127-137
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• 2000

In this paper, we consider hierarchical Bayesian analysis for P(Y < X) using Gibbs sampler, where X and Y are independent normal distributions with unknown means and variances, respectively. Also numerical study using real data is provided.

• The Journal of Korean Society for School & Community Health Education
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• v.15 no.3
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• pp.105-125
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• 2014

Background: The purpose of this study was to evaluate reliability and validity of a 27-item Korean Version of the Impact of Weight on Quality of Life in adolescents ($IWQOL-Kids^{(C)}$: Korean Version). Methods: This instrument was administered to 872 adolescents (mean z-BMI: 2.61, mean $age{\pm}SD$: $13.9{\pm}1.2$, male: 51.9%). Reliability was tested by internal consistency method and item analysis, validity test was performed by index of content validity, exploratory factor analysis, confirmatory factor analysis and concurrent validity. Sensitivity was tested by ANOVA and t-test. Analyses were performed using SPSS and Amos 18.0. Results: By an exploratory factor analysis, 4 factors were extracted; 'Body esteem' consisted of 9 items with 35.9% of variance (social life: 6 items, 10.23%, physical comfort: 6 items, 8.21%, family relations: 6 items, 7.0%). Four factors explained 61.34% of total variance. Internal consistency coefficients ranged from .766 to .929 for scales on 27 items and equal to .920 for total score for both the 26-item and 27-item tools. A confirmatory factor analysis was conducted for the convergent validity and discriminant validity. The standardized factor loadings to test the convergent validity showed more than .5(C.R<1.965) on all paths after deletion of item PC1 (avoid stairs). The average variances extracted were more than .50 and the construct reliabilities were more than .70. The average variances extracted were stronger than the squares of correlation coefficient of inter-latent variables. Conclusions: These results support that the $IWQOL-Kids^{(C)}$: Korean Version with a 26-item is a reliable and valid tool in Korean obese adolescents.

• The Journal of Engineering Geology
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• v.16 no.1 s.47
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• pp.15-21
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• 2006

Sandy soils obtained from the field were examined by the way of particle analyses. The hydraulic conductivity values of the disturbed soil samples were measured by the falling head method. Then the correlations between the hydraulic conductivity and particle distribution were defined. The soil which was a product of the weathering of the granitic rocks belonged to sand and loamy sand area in a sand-silt-clay triangular diagram. The measurements of hydraulic conductivity were $1.15X10^{-5}\sim7.31X10^{-4}cm/sec$ which is the range of sand and silt. It was clearly observed that the hydraulic conductivity measurements of the sandy soils showed stronger correlations with the particle variances rather than the mean grain sizes. The larger the variances, the smaller the hydraulic conductivity measurements. The sandy soil which was a product of weathered granite and whose mean grain size was $0.38\sim1.97mm$ showed regression curves of $y=6.0E-5x^{-1.4}$ in a correlations between hydraulic conductivity and particle variances. Accordingly, it is clearly concluded that making estimates with-out any consideration about particle variances can produce serious errors.

• Korean Journal of Microbiology
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• v.30 no.3
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• pp.193-198
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• 1992

Environmental parameters and physiological characteristics of heterotrophic bacterial isolates were compared by factor analysis to investigate the influences of river barrage construction on the ecosystem of Naktong River Estuary. Aftcr the construction of river barrage, the influence of seawater was no longer significant. ant1 the influences of nutrients loading were increased from 50.7% to 77.1% of the environmental variances before and after the construction, respectively. The interpretations of features of bacterial physiological characteristics were closely related to environmental parameters as the results of factor analysis. But. differing from the environmental variances. it was found that the halophilic feature was the third factor of bacterial characteristics after the construction of river barrage. This suggests that the stability of Naktong estuarine ecosystem and heterotrophic bacterial characteristics are not established till now.

• Journal of the Korean Society of Costume
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• v.60 no.1
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• pp.43-55
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• 2010

To pursue youth and agelessness can be regarded as a global trend today. The younger a woman recognizes herself to be, the more sensation seeking tendency and the more active fashion exploratory behavior of younger generation she would show. This study attempted to empirically examine the relationship between sensation seeking behavior and fashion exploratory behavior according to the difference age in women in their 30's to 50s'. After the survey, a total of 480 questionnaires was used for data analysis. The results of this study are as follows, 1. It was found that there was a very high correlation among cognitive ages, and the lower cognitive age a woman had, the higher difference age she showed. 2. Sensation seeking tendency of adult women was shown in two factors of change seeking and artistic sensation seeking, and these factors accounted for 73.99% of the total variances. Fashion exploratory behavior had 4 factors such as fashion leadership, behavior of hedonic shopping, behavior of clothing communication and behavior of clothing purchase with taking a risk, and these four factors accounted for 75.87% of the total variances. 3. The higher difference age and the higher tendency of sensation seeking an adult woman had, the higher fashion exploratory behavior was shown, and the higher the difference age, the higher tendency of change seeking and artistic sensation seeking.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.1
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• pp.1-6
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• 2001

Additive and dominance genetic variances were estimated for purebred Landrace selected with line breeding from 1989 to 1995 at Miyazaki Livestock Experiment Station, Kawaminami Branch. Ten body measurements, two reproductive traits and fifteen carcass traits were analyzed with single-trait mixed model analysis. The estimates of narrow-sense heritabilities by additive model were in the range of 0.07 to 0.46 for body measurements, 0.05 to 0.14 for reproductive traits, and 0.05 to 0.68 for carcass traits. The additive model tended to slightly overestimate the narrow-sense heritabilities as compared to the additive and dominance model. The proportion of the dominance variance to total genetic variance ranged from 0.11 to 0.91 for body measurements, 0.00 to 0.65 for reproductive traits, and 0.00 to 0.86 for carcass traits. Large differences among traits were found in the ratio of dominance to total genetic variance. These results suggested that dominance effect would affect the expression of all ten body measurements, one reproductive trait, and nine carcass traits. It is justified to consider the dominance effects in genetic evaluation of the selected lines for those traits.

• The Mathematical Education
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• v.45 no.2 s.113
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• pp.145-154
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• 2006

The main purpose of this study is to investigate the effect of departures from normality and equal variance on the two-sample test when the variances are unknown. We have found that type I error brought about a little bit change which is ignorable in relation to kurtosis. But the change of type I error was mainly based on the skewness of the parent population. In introductory statistics classes where data analysis includes techniques for detecting skewness of two populations, we recommend the two-sample t-test when maximal skewness of two populations is smalter than the value 4 when the variances seem equal. Furthermore, our simulations reveal that the two-sample t-test appears somewhat more robust than that of z-test if the assumption of equal variance is satisfied. In the case of unequal variance, the two-sample t-test appears somewhat more robust provided the t-statistic using Satterthwaite's approximate degrees of freedom.