• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.39-39
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• 2015

극치 수문(Hydrologic extremes)분야에서는 수문자료의 분포에 따라 Gumbel, GEV, 그리고 GLO 분포와 같은 다양한 확률통계 분포형이 존재한다. GEV와 GLO 분포형의 경우 Gumbel 분포형과 달리 형상매개변수가 포함된 3변수 분포형으로써 이상 기후 현상으로 인한 잦은 극치 수문사상을 표현하는데 좀 더 유연한 것으로 알려져 있다. 특히 GLO 분포형의 경우 영국에서 홍수빈도해석 시 적정분포형으로 선정된바 있다(Institute of Hydrology, 1999). 다양한 분포형 중에서 표본 자료를 대표할 수 있는 분포형을 선정하는 통계적 기법이 적합도 검정이다. 적합도 검정에는 $x^2$-검정, Cramer von-Mises 검정, Kolmogorov-Smirnov 검정, PPCC(probability plot correlation coefficient, 확률도시 상관계수)검정 등이 있으며 그 중 PPCC 검정은 이용방법이 간편하면서도 뛰어난 기각능력을 보이는 것으로 알려져 있다. 본 연구에서는 극치 수문분야에서 널리 이용되고 있는 GLO 분포형을 대상으로 자료의 왜곡도 영향을 고려할 수 있는 확률도시 상관계수 검정의 검정통계량을 추정하여 보았다.

• Journal of the Korean Data and Information Science Society
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• v.25 no.5
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• pp.1025-1038
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• 2014

Linear mixed model has often been utilized for genetic association analysis with family-based samples. The correlation matrix for family-based samples is constructed with kinship coefficient and assumes that parental phenotypes are independent and the amount of correlations between parent and offspring is same as that of correlations between siblings. However, for instance, there are positive correlations between parental heights, which indicates that the assumption for correlation matrix is often violated. The statistical validity and power are affected by the appropriateness of assumed variance covariance matrix, and in this thesis, we provide the linear mixed model with flexible variance covariance matrix. Our results show that the proposed method is usually more efficient than existing approaches, and its application to genome-wide association study of body mass index illustrates the practical value in real data analysis.

• The Korean Journal of Applied Statistics
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• v.31 no.2
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• pp.241-251
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• 2018

The analysis of gene sets in microarray has advantages in interpreting biological functions and increasing statistical powers. Many statistical methods have been proposed for detecting significant gene sets that show relations between genes and phenotypes, but there is no consensus about which is the best to perform gene sets analysis and permutation based tests are considered as standard tools. When many gene sets are tested simultaneously, a large number of random permutations are needed for multiple testing with a high computational cost. In this paper, several parametric approximations are considered as alternatives of the permutation distribution and the moment based gene set test has shown the best performance for providing p-values of the permutation test closely and quickly on a general framework.

• The Korean Journal of Applied Statistics
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• v.23 no.6
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• pp.1103-1113
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• 2010

An extensively used approach for family based association test(FBAT) is compared with the sib transmission/disequilibrium test(S-TDT), and in particular the adjusted S-TDT, in which the covariance among related siblings is taken into consideration, can provide a more sensitive test statistic for association. A simulation study comparing the three test statistics demonstrates that the type I error rates of all three tests are larger than the prespecified significance level and the power of the FBAT is lower than those of the other two tests. More detailed studies are required in order to assess the influence of the assumed conditions in FBAT on the efficiency of the test.

• The Korean Journal of Applied Statistics
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• v.12 no.1
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• pp.225-239
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• 1999

범주형 자료에 대하여 탐색적 자료분석을 할 수 있는 기존의 여러 그림들을 변수의 수가 많아지면 시각적인 식별이 어렵다는 단점이 있다. 본 논문에서는 삼차원이상의 다차원 범주형 자료를 이차원 평면성에 표현할 수 있는 링차트(ring chart)를 제안한다. 각 칸의 확률값을 표현하는 링차트는 범주형 자료의 구조 전체를 시각적으로 파악할 수 있으며, 관측값을 표준화한 링차트는 변수들간의 연관성 여부를 시각적으로 판단하는데 유용한 정보를 제공한다. 삼차원이상의 자료에서는 이중 링차트(조건부 링차트)를 개발하여 일차 및 이차교호작용 검정까지도 가능하다. 또한, 관측값과 잔차를 동시에 표현한 잔차 링차트는 설정된 모형의 적합성 여부를 시각적으로 평가할 수 있는 장점이 있다.

• Journal of Korea Water Resources Association
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• v.47 no.2
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• pp.161-170
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• 2014

It is important to estimate an appropriate quantile for design of hydraulic structure. For this purpose, it is necessary to find the appropriate probability distribution which can represent the sample data well. Probability plot correlation coefficient test as one of goodness-of-fit test, is recently developed and has been known as a simple and powerful method. In this study, probability plot correlation coefficient test statistics using the plotting position considering the coefficients of skewness for the GEV distribution is derived, and represented by the regression equation. Monte-Carlo method is also performed to compare the rejection power between each method. As the results, the probability plot correlation coefficient test which is derived in this study is better than the others. In particular, when sample size is small and distribution has the shape parameter, rejection power of probability plot correlation coefficient test considering the coefficients of skewness is bigger than the others.

• The Korean Journal of Applied Statistics
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• v.28 no.2
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• pp.221-230
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• 2015

Traditionally, sib-pair linkage analysis with repeated measures has employed linear mixed models, but it suffers from the lack of power to find genetic marker loci associated with a phenotype of interest. In this paper, we use a gamma mixed model to improve sib-pair linkage analysis and compare it with a linear mixed model in terms of power and Type I error. We illustrate that the use of gamma mixed model can achieve higher power than linear mixed model with Genetic Analysis Workshop 13 data.

• Journal of the Korean Data and Information Science Society
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• v.28 no.6
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• pp.1349-1360
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• 2017

This study was conducted to estimate the genetic parameters for common ketosis indicators (${\beta}$-hydroxybutyrate acid, BHBA; milk acetone), feed intake efficiency indicator (energy-corrected milk, ECM), and milk yield (MY) in Korean Holstein. A total of 75,072 monthly test-day records from 14,397 first parity cows were collected, between 2012 and 2016, from Korea animal improvement association enrolled farms. Variance components were estimated using a multiple trait random regression model. The heritability of BHBA and acetone levels ranged from 0.06 to 0.15 at different DIMs. The phenotypic and genetic correlations between BHBA and acetone were between 0.73 and 0.90, and between 0.93 and 0.98, respectively. The phenotypic correlation between BHBA and MY, between acetone and MY, between BHBA and ECM, and between acetone and ECM ranged from -0.18 to -0.05, -0.23 to -0.05, 0 to 0.10, and -0.09 to 0.01, respectively. Genetic correlation estimates between BHBA and MY, between acetone and MY, between BHBA and ECM, and between acetone and ECM also ranged from -0.55 to 0.05, -0.62 to -0.04, -0.10 to 0.11, and -0.20 to 0.00, respectively. We hope that these results would greatly assist in the improvement of ketosis disease in the local Holsteins.

• Communications for Statistical Applications and Methods
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• v.4 no.3
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• pp.645-661
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• 1997

연속형 변수들의 상관관계와 범주형 변수들의 연관성 측도들을 비교 연구하였다. 이 연구를 위하여 연속형 변수들이며 +1에서 -1까지 완벽한 상관관계를 갖고 있는 2 변량 정규분포를 이용하여 2$\times$2 분할표와 확장하여 일반적인 I$\times$J 분할표를 대신하는 3$\times$3 분할표를 생성하였다. 2 차원 분할표에서 정의된 연관성 측도들을 구하여 논의하였는데 2$\times$2 분할표에서는 교차적비 $\alpha$ 통계량과 교차적비의 함수로 표현되는 Yule [1912]의 Q와 Y의 통계량 그리고 상관계수 R 통계량과 R 통계량의 함수인 P 통계량을 설명하고 생성된 분할표에서 구한 통계량값을 분석하였으며, 3$\times$3 분할표에서는 Pearson의 독립성 검정통계량 $X^2$의 함수로 표현되는 P. T. V 통계량과 Goodman과 Kruskal [1954]의 $\lambda_{C/R}$통계량과 Light와 Margolin [1971]의 $\tau_{R/C}$ 통계량을 설명하고 그 값들을 Pearson의 상관계수와 비교 분석하였다.

• Journal of Animal Science and Technology
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• v.54 no.2
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• pp.83-87
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• 2012

The purpose of this study was to estimate genetic parameters for productive traits in swine. Productive traits were considered on average daily gain (ADG), body height (BH) and body length (BL). Genetic analysis was consisted of 18,668 heads for productive traits which were based on on-farm performance tested from May, 2007 to Apr, 2011. For estimating genetic parameters on productive traits, single best model was fitted after finding source of variance on fixed and random effects and estimated with a multiple trait animal model by using DF-REML (Derivative-Free Restricted Maximum Likelihood). The estimated heritabilities of Duroc, Berkshire, Landrace and Yorkshire 0.22-0.58 for the average daily gain, 0.34-0.41 for the body height and 0.4-0.52 for the body length, respectively. Phenotypic correlations of average daily gain with body height and body length for the four breeds were 0.42-0.48, 0.53-0.58, 0.34-0.46 and 0.47-0.56, respectively. Phenotypic correlations of body height with body length were 0.41, 0.57, 0.52, 0.59, respectively. The estimated genetic correlation coefficients of average daily gain with body height and body length estimated for the four breeds were 0.34-0.47, 0.70-0.75, 0.17-0.38 and 0.50-0.53, respectively. The estimated genetic correlation coefficients of body height with body length were 0.57, 0.69, 0.61 and 0.71, respectively.