• Communications for Statistical Applications and Methods
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• v.17 no.4
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• pp.515-525
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• 2010

We investigated design-based properties of the ordinary least square estimator(OLSE) and the weighted least square estimator(WLSE) in a panel regression model. Given a complex data we derive the magnitude of the design-based bias of two estimators and show that the bias of WLSE is smaller than that of OLSE. We also conducted a simulation study using Korean welfare panel data in order to compare design-based properties of two estimators numerically. In the study we found the followings. First, the relative bias of OLSE is nearly two times larger than that of WLSE and the bias ratio of OLSE is greater than that of WLSE. Also the relative bias of OLSE remains steady but that of WLSE becomes smaller as the sample size increases. Next, both the variance and mean square error(MSE) of two estimators decrease when the sample size increases. Also there is a tendency that the proportion of squared bias in MSE of OLSE increases as the sample size increase, but that of WLSE decreases. Finally, the variance of OLSE is smaller than that of WLSE in almost all cases and the MSE of OLSE is smaller in many cases. However, the number of cases of larger MSE of OLSE increases when the sample size increases.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.5
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• pp.620-625
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• 2005

Correlation of microsatellite heterozygosity with performance or heterosis was reported in wild animal populations and domestic animal populations, but the correlation with heterosis in a crossbreeding F$_1$ pig population remained uncertain. To explore this, we had random selected and mated Yorkshire${\times}$Meishan (F, n = 82) and their reciprocal (G, n = 47) to F$_1$, and used the two straightbreds as control groups (Yorkshire = 34, Meishan = 55), and observed the heterosis of birth weight (BWT), average daily gain (ADG) and feed and meat ratio (FMR). Two Kinds of measurement-individual heterozygosity (IH) and individual mean d$^2$ (lg value, ID) were used as index of heterozygosity and variance from 39 microsatellite marker loci to perform univariate regression analysis against heterosis. We detected significant correlation of IH with BWT in all of F$_1$ (F+G) and in F. We observed significant correlation of ID with ADG in all of F$_1$ (F+G), and with FMR in all of F$_1$ (F+G) and in F. There was significant maternal effect on heterosis, which was indicated by significant difference of means and distribution of heterosis between F and G. This difference was consistent with distributions of IH and ID, and with difference of means in F and G. From this study, it would be suggested that the two kinds of genetic index could be used to explore the genetic basis of heterosis in crossbreeding populations but could not determine which is better.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.25 no.2
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• pp.138-146
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• 2022

Purpose: Children with celiac disease (CD) are at an increased risk of low bone mineral density (BMD) owing to malabsorption of fat-soluble vitamins, inflammation, and malnutrition. This study aimed to determine the prevalence and risk factors for low BMD in Iranian children with CD. Methods: This prospective cohort study examined 149 Iranian children with CD between 2011 and 2018 at Zabol University of Medical Sciences. BMD was measured using dual-energy X-ray absorptiometry. Demographic, clinical, and laboratory data were collected from patients' medical records. Logistic regression analysis was performed to identify the factors associated with low areal BMD (BMD-Z <-2) in the lumbar spine and femoral neck. Descriptive data were analyzed using the mean, standard deviation, and relative frequency. Data were analyzed using the chi-square test, t-test, and analysis of variance. Results: Of the 149 children with CD, 27.5% had osteoporosis. The mean body mass index (BMI) Z score was -1.28±1.2. Lower BMI was associated with a higher likelihood of BMD-Z (odds ratio 2.17; p≤0.05). Conclusion: Overall, the findings of this study showed that there was no correlation among Marsh classification, presence of specific human leukocyte antigens, and low BMD in Iranian children with CD. BMI can be a predictor of bone density in children with CD and may be applied clinically in early screenings to evaluate the bone health status in these children.

• PNF and Movement
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• v.19 no.3
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• pp.435-440
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• 2021

Purpose: The purpose of this study is to investigate the effects of older adult's head-turn gait on gait parameters by comparing with head oriented forward gait and to provide criteria for their risk of falling compared to young adult. Methods: The subjects were 19 young adults in their 20s and 18 older adults in their 60s or above residing in Daegu or Gyeongsangbuk-do. To evaluate their gait parameters, spatiotemporal gait parameters were measured using a gait analysis tool (Legsys, BioSensics, USA) under two conditions: 1) walking while keeping one's eyes forward and 2) walking while turning the head. The measurement for each test was performed after one practice session, and the mean value of three measurements was analyzed. The collected data were statistically processed using a two-way analysis of variance (ANOVA) to compare any differences in gait parameters between the two groups under the two conditions. The statistical significance level was set at α=0.05. Results: According to the comparison of gait parameters in young adult and older adult between the head oriented forward gait and head-turn gait, statistically significant differences were observed in two parameters: stride length according to the height ratio and stride speed obtained by dividing the stride length according to the height ratio by time (p<0.05). Conclusion: The results of this study indicate that the head-turn gait causes greater differences in stride length and speed among older adult than in young adult and therefore can act as a cause of falling.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1979.05a
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• pp.3.2-3
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• 1979

Bone conduction loss is one of the most common complication in chronic otitis media, and is mostly high frequency loss. Of 233 tympanomastoidectomy ears, 187 ears were considered eligible for this study. A histopathological change was examined in the natural otitis media of guinea pigs. It is our intention to analyze the pattern of bone conduction loss in chronic otitis media, and to correlate this findings with clinical and pathological changes in human and animal otitis media. l) In unilateral cases, a significant difference in bone conduction threshold was observed between normal and diseased ears, and between each frequency with significant interaction between 2KHz and 4KHz (p 0.01). 2) Using one way analysis of variance, mean bone conduction was compared with the duration of disease. We observed a significant difference (p 0.05) between each group of duration, except between 11-15 and 15-20 years group. 3) A comparison of bone conduction between stapes loss group and intact stapes group revealed significant t ratio (p 0.01) at each frequency. The effect of stapes loss on each frequency was evaluated, using one way analysis of variance. there were significant difference(p 0.05) between 250Hz and 500Hz. and between 2KHz and 4KHz. 4) A comparison of bone conduction between round window obliteration and nonobliteration group revealed significant t ratio (p 0.01) at each frequency. Using one way analysis of variance. the effect of round window obliteration was evaluated in each frequency. We observed significant difference (p 0.05) between 250Hz and 500Hz. and between 2KHz and 4KHz. 5) A comparison of bone conduction between cholesteatoma and non -cholesteatoma group revealed significant t ratio (p 0.01) only in 2KHz and 4KHz. No significant differency was observed in mean bone conduction. 6) In a histopathological study of natural otitis media in guinea pig, we observed inflammatory infiltration of the round window membrane, serofibrinous precipitate in the scala tympani, and degeneration of the organ of Corti most significant near the basal turn. These changes would explain high tone bone conduction loss in the process of chronic otitis media.

• Journal of Nutrition and Health
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• v.52 no.4
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• pp.408-411
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• 2019

Purpose: This study investigated the effect of bioactive Yeonsan Ogye peptides (YOPs) intake on changes in the hepatic anti-oxidant indexes in male rats. Methods: Sprague-Dawley male rats were divided into 3 groups and given a casein-based AIN-93G diet and distilled water ad libitum without any added YOPs (control), distilled water with 250 mg of YOPs (Y250), or 500 mg of YOPs (Y500) per kg of body weight for 4 weeks. YOP dose was decided as referred to in the referenced study where toxicity did not occur. The hepatic anti-oxidant indexes were determined using a commercial kit. Statistical analysis was performed using SPSS version 23.0 and are expressed as $mean{\pm}standard$ error of mean. Differences among the groups were evaluated by one-way analysis of variance followed by post hoc Duncan's multiple comparisons test. Results: There were no differences in the body weights, weight gain, food intake, food efficiency ratio, or organ weight, including liver, kidney, spleen, thymus, and epididymal fat, among all of the groups. The hepatic nitric oxide (NO) level in the Y500 group was lower than that in the control and Y250 groups, and the hepatic malondialdehyde (MDA) level was lower in the Y500 group than in the Y250 group. The differences in hepatic superoxide dismutase (SOD) and catalase (CAT) activities were not statistically significant between the groups. From these results we speculated that YOPs may have anti-oxidative abilities to regulate NO and MDA production without affecting SOD and CAT activities. Conclusion: YOPs are presumed to act as anti-oxidants in the animal or human body.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.253-260
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• 2009

This paper, mathematically analyzes the performance of newly proposed TR-UWB system which the frequency components of a UWB pulse were processed so that the system could be implemented with ADCs of a few MHz sampling rate, and presents the comparison with an existing frequency-domain based TR-UWB system. The comparison is mainly based on the SNR ratio which depends on the mean and the variance of the frequency components. We also shows that the simulation results to support the theoretical analysis where the comparison is made under the IEEE 802.15.3a channel model as well as AWGN channel.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.1
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• pp.122-126
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• 2010

Purpose: F-18-FPCIT that shows strong familiarity with DAT located at a neural terminal site offers diagnostic information about DAT density state in the region of the striatum especially Parkinson's disease. In this study, we altered the iteration and subset and measured SUV${\pm}$SD and Contrasts from phantom images which set up to specific iteration and subset. So, we are going to suggest the appropriate range of the iteration and subset. Materials and Methods: This study has been performed with 10 normal volunteers who don't have any history of Parkinson's disease or cerebral disease and Flangeless Esser PET Phantom from Data Spectrum Corporation. $5.3{\pm}0.2$ mCi of F-18-FPCIT was injected to the normal group and PET Phantom was assembled by ACR PET Phantom Instructions and it's actual ratio between hot spheres and background was 2.35 to 1. Brain and Phantom images were acquired after 3 hours from the time of the injection and images were acquired for ten minutes. Basically, SIEMENS Bio graph 40 True-point was used and True-X method was applied for image reconstruction method. The iteration and Subset were set to 2 iterations, 8 subsets, 3 iterations, 16 subsets, 6 iterations, 16 subsets, 8 iterations, 16 subsets and 8 iterations, 21 subsets respectively. To measure SUVs on the brain images, ROIs were drawn on the right Putamen. Also, Coefficient of variance (CV) was calculated to indicate the uniformity at each iteration and subset combinations. On the phantom study, we measured the actual ratio between hot spheres and back ground at each combinations. Same size's ROIs were drawn on the same slide and location. Results: Mean SUVs were 10.60, 12.83, 13.87, 13.98 and 13.5 at each combination. The range of fluctuation by sets were 22.36%, 10.34%, 1.1%, and 4.8% respectively. The range of fluctuation of mean SUV was lowest between 6 iterations 16 subsets and 8 iterations 16 subsets. CV showed 9.07%, 11.46%, 13.56%, 14.91% and 19.47% respectively. This means that the numerical value of the iteration and subset gets higher the image's uniformity gets worse. The range of fluctuation of CV by sets were 2.39, 2.1, 1.35, and 4.56. The range of fluctuation of uniformity was lowest between 6 iterations, 16 subsets and 8 iterations, 16 subsets. In the contrast test, it showed 1.92:1, 2.12:1, 2.10:1, 2.13:1 and 2.11:1 at each iteration and subset combinations. A Setting of 8 iterations and 16 subsets reappeared most close ratio between hot spheres and background. Conclusion: Findings on this study, SUVs and uniformity might be calculated differently caused by variable reconstruction parameters like filter or FWHM. Mean SUV and uniformity showed the lowest range of fluctuation at 6 iterations 16 subsets and 8 iterations 16 subsets. Also, 8 iterations 16 subsets showed the nearest hot sphere to background ratio compared with others. But it can not be concluded that only 6 iterations 16 subsets and 8 iterations 16 subsets can make right images for the clinical diagnosis. There might be more factors that can make better images. For more exact clinical diagnosis through the quantitative analysis of DAT density in the region of striatum we need to secure healthy people's quantitative values.

• Water for future
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• v.10 no.1
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• pp.39-51
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• 1977

The purpose of this study is to make "The Rainfall Frequency Atlas in Korea" by the analytical method with new hydrological concepts. In this study, all of the rainfall datas in Korea was used for surveying of the basic data, and so we can get 103 sites for annual rainfall data and 100 sites for the max. in a day that are suitable to the purpose of the study. The above data groups are possible to estimate the normal standard period by the moving average method with $\pm$5% of significance level of variance ratio between the max. and min. moving average and arithmetic mean, but it may be impossible to study until 1990's for the short duration under 18-hr because the sites, having the short duration data, are only 12. The results of this study are as follows; 1. The normal standard period estimated by the moving average method is 20 year with $\pm$5% of significance level of variance ratio, and 30 year with$\pm$2-3%. 2. For the annual and max. rainfall in a day, it is possible to make the rainfall frequency atlas with 30normal standard period, but it may be impossible until 1990's for short duration. 3. "Y-k method" developed by writer is best suitable in the rainfal frequency analysis in Korea because of its convenience and reduction in the amount of calculation compared with other methods. 4. To improve the utilization of the rainfall frequency atlas, the larger-sized and the more detailed iso-precipitation atlas must be drawn.atlas must be drawn.

• Magazine of the Korean Society of Agricultural Engineers
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• v.31 no.4
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• pp.96-110
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• 1989

To suggest the fundamental data for the estimation of crop evaportranspiration by the ca- lculated coefficients for estimating the radiation suitable to the different regions of korea in application of Penman equcation, the daily data such as sc(skycover), n(actual sunshine hours), N(possible sunshine hours), Rs(horizontal solar radiation) and Ra(extraterrestial solar radiation) for 10 years (from 1977 to 1986) collected from 19 meteorological stations were analysed. The results are summarized as follows : 1. The coefficients a, b and c for estimating the radiation taken by the regression method with the daily and monthly mean data of the skycover and the ratio of Rs to Ra were shown as a=0.619, b= -0.0202, c= -0.0023 and a=0.64, b=0.0377 c=0.0001 in ave- rage respectively. 2. The coefficients a and b for estimating the radiation analysed by the regression and arithmetic method from the daily ratio of sunshine hours and Rs to Ra were shown as a= 0.157, b= 0.529, and a=0.119, b= 0.726 in average, respectively. 3. The coefficients a and b for estimating the radiation calculated by the regression me- thod based on the monthly ratio of sunshine hours and radiation were shown as a=0. 319 and b= 0.557 in average. 4. The values of a and b for estimating the radiation taken from the relationship between the daily ratio of sunshine hours and radiation showed high significance level. 5. The standard deviation and the coefficient of variance between the radiation calculated from the coefficients by the regression and arithmetic method with the daily data and the actual radiation were analysed and compared to the results by the coefficients of the modified Penman method (a=0.18, b=0.55) and by those of the F.A.O inodified Penman method(a=0.25, b=0.5). The standard deviation and the coefficient of varia- nce by the regression method in this study showed the lowest value. 6. From the above results, it is suggested that regression method using the coefficients taken from the relationship between the ratio of sunshine hours and the ratio of radia- tion based on the daily data has the highest accuracy in estimating the radiation. 7. The average reference crop evapotranspiration estimating by the modified Penman me- thod using the coefficients a and b derived by the regression method from the daily meterological data was closer to the actual evapotsranspiration of grass measured in Suwon area than the estimated evapotranspiration by the modified Penman method and the F.A.O modified Penman method.