• Communications for Statistical Applications and Methods
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• 제24권3호
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• pp.241-254
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• 2017

Drawing a sample can be costly or time consuming in some studies. However, it may be possible to rank the sampling units according to some baseline auxiliary covariates, which are easily obtainable, and/or cost efficient. Ranked set sampling (RSS) is a method to achieve this goal. In this paper, we propose a modified approach of the RSS method to allocate units into an experimental study that compares L groups. Computer simulation estimates the empirical nominal values and the empirical power values for the test procedure of comparing L different groups using modified RSS based on the regression approach in analysis of covariance (ANCOVA) models. A comparison to simple random sampling (SRS) is made to demonstrate efficiency. The results indicate that the required sample sizes for a given precision are smaller under RSS than under SRS. The modified RSS protocol was applied to an experimental study. The experimental study was designed to obtain a better understanding of the pathways by which positive experiences (i.e., goal completion) contribute to higher levels of happiness, well-being, and life satisfaction. The use of the RSS method resulted in a cost reduction associated with smaller sample size without losing the precision of the analysis.

• 한국산학기술학회논문지
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• 제18권5호
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• pp.581-586
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• 2017

사과, 배, 포도 등 과수 고품질 생산과 생산성 향상을 위한 시설현대화 정책은 사업 참여농가들의 생산량이 증가하는 등 사업의 성과가 높은 것으로 보고되고 있어, 생산농가의 정책 참여의향이 높은 것으로 보인다. 그 동안 이 사업에 참여한 생산농가는 품종갱신, 친환경과원관리, 배수시설, 지주시설, 관수관비시설, 비가림시설, 다겹보온커텐설치, 작업로 정비, 야생동물 방지시설, 서리피해방지시설 등 여러 사업에 참여했다. 이 논문은 우리나라 과수산업에서 생산비중이 높은 품목(사과, 배, 포도) 생산농가를 대상으로 정책수행의 성과를 측정하였다. 우리는 이를 위해 참여농가 약 300호를 대상으로 설문조사를 실시하였다. 설문조사 자료를 토대로 공변량매칭 및 PSM 방법을 이용하여, 생산량, 농가판매가격, 당도 증가율, 생산비 등 다양한 변수들에 대한 사업 전후의 성과 변화를 비교 검토하였다. 검토결과, 여러 세부 사업 중 사과의 경우는 주로 품종갱신, 배는 주로 관수관비시설 설치, 포도는 비가람시설의 설치사업에 주로 참여하여 양적 생산량 증대는 물론 당도개선 등 과실의 품질향상에도 상당한 기여를 한 것으로 파악된다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권14호
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• pp.5655-5661
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• 2015

Purpose: To assess the role of two adjuvant chemotherapy regimens, anthracycline-based and CMF on disease free survival and overall survival breast cancer patients by meta-analysis approach in Eastern Mediterranean and Asian countries to determine which is more effective and evaluate the appropriateness and efficiency of two different proposed statistical models. Materials and Methods: Survival curves were digitized and the survival proportions and times were extracted and modeled to appropriate covariates by two multivariate mixed effects models. Studies which reported disease free survival and overall survival curves for anthracycline-based or CMF as adjuvant chemotherapy that were published in English in the Eastern Mediterranean region and Asia were included in this systematic review. The two transformations of survival probabilities (Ln (-Ln(S)) and Ln(S/ (1-S))) as dependent variables were modeled by a multivariate mixed model to same covariates in order to have precise estimations with high power and appropriate interpretation of covariate effects. The analysis was carried out with SAS Proc MIXED and STATA software. Results: A total of 32 studies from the published literature were analysed, covering 4,092 patients who received anthracycline-based and 2,501 treated with CMF for the disease free survival and in order to analyze the overall survival, 13 studies reported the overall survival curves in which 2,050 cases were treated with anthracycline-based and 1,282 with CMF regimens. Conclusions: The findings illustrated that the model with dependent variable Ln (-Ln(S)) had more precise estimations of the covariate effects and showed significant difference between the effects of two adjuvant chemotherapy regimens. Anthracycline-based treatment gave better disease free survival and overall survival. As an IPD meta-analysis in the Italy the results of Angelo et al in 2011 also confirmed that anthracycline-based regimens were more effective for survival of breast cancer patients. The findings of Zare et al 2012 on disease free survival curves in Asia also provided similar evidence.

• Asian-Australasian Journal of Animal Sciences
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• 제21권9호
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• pp.1227-1232
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• 2008

Carcass characteristics data of Hanwoo (N = 1,084) were collected from two stations of the National Livestock Institute of Animal Science (NIAS), Korea and records from thirteen individual cow-calf operators were analyzed to estimate variance and covariance components and the effect of different slaughter endpoints. Carcass traits analyzed were cold carcass weight (CWT, kg), REA (rib eye area, cm2), back fat thickness (mm) and marbling score (1-7). Four different models were examined. All models included sex and contemporary group as fixed effects and the animal's direct genetic potential and environment as random effects. The first model fitted a linear covariate of age at slaughter. The second model fitted both linear and quadratic covariates of age at slaughter. The third model fitted a linear covariate of body weight at slaughter. The fourth model fitted both linear covariates of age at slaughter and body weight at slaughter. Variance components were estimated using the REML procedure with Gibb's sampler. Heritability estimate of CWT was in the range of 0.08-0.11 depending on the model applied. Heritability estimates of BF, REA and MS were in the ranges of 0.23-0.28, 0.19-0.26, and 0.44-0.45, respectively. Genetic correlations between CWT and BF, between CWT and REA, and between CWT and MS were in the ranges of -0.33 - -0.14, 0.73-0.84, and -0.01- 0.11, respectively. Genetic correlations between REA and BF, between MS and BF and between REA and MS were in the ranges of -0.82 ~ -0.72, 0.04~0.28 and -0.08 ~ -0.02, respectively. Variance and covariance components estimated varied by model with different slaughter endpoints. Body weight endpoint was more effective for direct selection in favor of yield traits and body weight endpoints affected more of the correlated response to selection for the traits of yield and quality of edible portion of beef.

• Asian-Australasian Journal of Animal Sciences
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• 제15권8호
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• pp.1178-1181
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• 2002

Records from a total of 202 crossbred pigs were classified by their ear type and coat color to examine the presence of interrelationships with growth performances. Crossbred pigs were F2 generations of full sib family out of ten Landrace sows bred by 5 Korean domestic boars. Heavily drooped ear type was predominant, 195 out of 202 pigs over the other two types (1 straight and 6 slightly drooped). Coat colors were classified as four categories, all white, all black, dominant white or dominant black. Ratio among coat color categories did not fall within Mendelian principle of independence regarding two loci involved. There was dependency between ear type and coat color. However, due to rarity of ear types other than heavy drooped, dependency comes from distribution of those rare ear types. Three least squares models to test the effect of ear type and coat colors on growth performances were analyzed. First model analyzed effects on birth weight, body weight at 3 and 6 weeks and ADG' before weaning and between 3 and 5 weeks of age. This model included sex in addition to ear type and coat color. Second model analyzed postweaning growth traits (initial weight, final weight and ADG between these periods) upon initiation of performance testing. This model included effects of sex, test group and start age (as a covariate) in addition. Third model was fit for fasted weight before slaughter and included the effects of sex, test group and age at slaughter (as a covariate). The effects of sex and ear type were not significant source of variation for all traits. Test group was a significant source of variation for all the postweaning traits. Effect of coat color was not significant until the initiation of performance testing and became significant then after. Least squares means of dominantly black pigs were significantly lower than the other three coat colored pigs in final weight around 195 days of age and in ADG from the start of performance test and final weight measure.

• 응용통계연구
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• 제26권3호
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• pp.413-420
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• 2013

확률적 날씨 발생기(Stochastic weather generator)는 일일 날씨를 생성하는데 일반적으로 사용되는 방법으로 최근에는 일반화선형모형에 기초한 확률적 날씨 발생 방법이 제안되었다. 본 논문에서는 서울지역의 일일 기온을 모형화하하기 위해서 일반화선형모형에 기초한 확률적 날씨 발생기를 고려하였다. 이 모형에서는 계절성을 나타내는 변수와 강우발생 유무가 공변수로 사용되었다. 일반적으로 확률적 날씨 발생기에서는 생성된 일일 날씨가 월별 또는 계절별 총강우량이나 평균온도에 충분한 변동을 만들어 내지 못하는 과대산포 현상이 발생하는데, 이러한 한계를 극복하기 위해 본 연구에서는 평활된 계절별 평균 온도를 일반화선형모형의 공변수로 추가하였다. 그리고 제안된 모형을 1961년부터 2011년까지 51년 동안의 서울지역 일일 평균 기온자료에 적용하였다.

• 대한화학회지
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• 제46권4호
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• pp.377-384
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• 2002

본 연구에서는 학생들이 사전 성취 수준에 따른 협동적 컴퓨터 보조 수업의 쇼과를 개념 이해도, 개념 적용력, 학습 동기 측면에서 조사하였다. 서울시의 중학교 2개 학급을 대상으로 분자 운동 단원에 대해 5차시 동산 수업을 실시하였다. 수업 처치 전, 학습 동기 검사를 실시하여 공변인으로 사용하였다. 사전 학업 성취도 검사 점수는 개념 관련 변인의 공변인으로 사용하였다. 중간고사 과학 성적을 조사하여 구획변인으로 사용하였다. 수업처치 후 , 개념검사, 개념 적용력 검사, 학습 동기 검사를 실시하였다. 이원 공변량 분석 결과 개념 검사와 개념 적용력 검사 점수에서는 처치 집단과 통제 집단 사이에 유의미한 차이가 없었다. 그러나 학습 동기 검사에서는 처치 집단의 점수가 통제 집단에 비하여 유의미하게 높았다.

• 농업생명과학연구
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• 제44권3호
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• pp.89-97
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• 2010

이 논문은 대기오염 개선에 따른 부수적 가치를 분석하기 위하여 가상가치평가법을 이용하였으며, 지불의사 유도방법으로는 이중 양분선택법을 적용하였다. 온실가스의 감축, 특히 이산화탄소 감축은 화석연료의 사용감소를 통해 대기오염물질의 감소라는 부수적 효과를 갖는다. 주요 분석결과를 정리하면 다음과 같다. 첫째, 대기오염 개선에 따른 부수적 가치는 연간 329,236원으로 분석되었다. 둘째, 지불의사금액의 가치 추정에 있어 사회 경제적 특성변수와 환경에 대한 인식을 포함한 분석모형의 적합성이 다소 개선되는 것으로 나타났다. 따라서 제시금액뿐만 아니라 사회 경제적 특성변수들을 포함한 분석모형을 적용하고 이를 통한 지불의사금액의 가치가 보다 타당할 것으로 판단된다.

• 한국융합학회논문지
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• 제12권12호
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• pp.519-528
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• 2021

본 연구는 간호 대학생을 대상으로 시뮬레이션 기반 인수인계 교육프로그램을 적용하여 학생들의 인수인계 수행능력과 인수인계 자신감에 미치는 효과를 검증하고자 한다. K도 소재 P시와 A시 소재 간호 대학생 104명에게 사전·사후 실험설계의 비동등성 대조군 유사 실험연구를 수행하였다. 자료 수집 기간은 2017년 10월 30일부터 11월 10일까지이며, 수집된 자료 분석은 SPSS WIN 21.0 프로그램을 이용하여 x² test, Fisher's exact test, independent t-test, ANCOVA with pretest value as covariate를 실시하였다. 효과를 검증한 결과 인수인계 수행능력에서 유의한 차이가 있는 것으로 나타났다. 본 연구에서 개발된 시뮬레이션 기반 인수인계 교육 프로그램은 간호대학생의 인수인계 수행능력을 증진하는 데 효과적인 인수인계 교육 프로그램으로 적용될 수 있을 것이다.

• 대한의용생체공학회:의공학회지
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• 제44권1호
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• pp.53-63
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• 2023

There have been many studies from the genetic system to physical activity and emotional expression such that there are gender differences. The purpose of this study was to determine how the structural characteristics of cortical thickness differ between males and females. This study used data from the Human Connectome Project (HCP). To analyze age-specific sexual dimorphisms of cortical thickness, selected 8-80 year old subjects were divided into five detailed age range groups according to each criterion. A total of 1,700 individual brain MRI T1 data were registered in stereotaxic space for analysis and classified into white matter (WM), gray matter (GM), and cerebro-spinal fluid (CSF). For surface-based analysis, the WM/GM surface was reconstructed from a spherical polygon model with 40962 vertices per hemisphere, and each vertex was extended to the GM/CSF boundary. Cortical thickness was then measured between each vertex using the t-link method. In the statistical analysis, intracranial volume was used as a covariate to exclude the effect of the difference in brain size of each individual, and the result of using age as a covariate was added to confirm the age effect within each group. Gender differences in cortical thickness had significant results by group. This may be an index to explain diseases with sexual dimorphism in prevalence or become a basis for explaining the characteristics of each sex that appear in behavior, personality, and aging. Therefore, the results of our study could be a criterion for age classification in future studies and for understanding 'normal' sexual dimorphism.