• The Mathematical Education
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• v.55 no.3
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• pp.251-279
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• 2016

There are many studies on 'how' students solve mathematical problems, but few of them sufficiently explained 'why' they have to solve the problems in their own different ways. As quantitative reasoning is the basis for algebraic reasoning, to scrutinize a student's way of dealing with quantities in a problem situation is critical for understanding why the student has to solve it in such a way. From our teaching experiments with two ninth-grade students, we found that emergences of a certain level of covariational reasoning were highly consistent across different types of problems within each participating student. They conceived the given problem situations at different levels of covariation and constructed their own quantity-structures. It led them to solve the problems with the resources accessible to their structures only, and never reconciled with the other's solving strategies even after having reflection and discussion on their solutions. It indicates that their own structure of quantities constrained the whole process of problem solving and they could not discard the structures. Based on the results, we argue that teachers, in order to provide practical supports for students' problem solving, need to focus on the students' way of covariational reasoning of problem situations.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.230-230
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• 2019

대규모순환패턴과 같은 기후시스템에서의 상태와 변화를 정량화하여 나타낸 기상인자는 수문기상학적 변수와 밀접한 연관이 있는 것으로 알려져 있으며, 이에 따라 비정상성 빈도해석의 수행에 있어서 확률분포모형의 매개변수에 대한 공변량으로 널리 활용되고 있다. 본 연구에서는 비정상성 강우빈도해석 시 매개변수의 공변량으로 우리나라의 극치강우의 장기경향성을 잘 반영할 수 있는 기상인자를 선정하고자 한다. 먼저, 시계열자료를 주기성을 가지는 내재모드함수와 장기경향성을 나타내는 잔여값으로 분해할 수 있는 앙상블 경험적 모드분해법을 이용하여 우리나라 전역에 분포된 61개 지점에서 관측된 연 최대치 강우자료의 평균 및 분산에 대한 잔여값을 추출하였다. 다음으로 11개의 월 단위 기상인자에 대한 계절별 연 평균 시계열과 추출된 평균 및 분산의 잔여값과의 상관계수를 산정하였다. 그 결과, 11개의 기상인자 중 Atlantic Meridional Mode (AMM), Atlantic Multi-decadal Oscillation (AMO), North Atlantic Oscillation (NAO)가 우리나라 연 최대치 강우자료의 평균 및 분산에 대한 장기경향성과 높은 상관성이 있는 것으로 나타났다. 계절적으로는 AMM과 AMO의 경우 이전 년도 가을철 평균이 전 지점 평균 약 0.6, NAO는 이전 년도 여름철 평균이 전 지점 평균 0.3 이상의 유의한 상관계수를 가지는 것으로 나타났다.

• Journal of East-West Nursing Research
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• v.14 no.1
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• pp.78-86
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• 2008

본 연구는 여대생의 건강증진행위를 설명하기 위하여, 문헌고찰을 통해 가설적 모형을 도출하고, 여대생을 대상으로 건강증진행위를 횡단적으로 조사하여 모형의 적합성과 모형에서 제시된 가설을 검증하는 서술적 상관관계 연구이다. 연구에 사용된 변수는 건강증진행위와 관련된 선행 문헌의 고찰을 근거로 선정되었으며, 총 280명의 자료가 최종 분석에 이용되었다. 설문지는 Pender의 건강증진모형을 기초로 하여 개발하였으며, 조정요인 5문항, 건강상태 지각 3문항, 건강 통제위 4문항, 자아 존중감 5문항, 건강증진 행위 24문항의 총 41문항으로 구성하여 사용하였다. 개발된 항목에 대하여 간호대학생들을 대상으로 사전 조사를 실시하여 최종적인 설문지를 완성하였다. 본 연구모형에 대한 구성개념의 파악을 위해서 탐색적 요인분석을 실시하였고, 측정항목에 대한 요인별 단일 차원성 확인 및 통계적 검정을 위해 확인적 요인분석을 실시하였다. 연구의 가설검증을 위해 공변량 구조분석을 실시하였다. 모형의 적합도는 카이제곱은 244.04(자유도=121, p<0.001), GFI=0.91, CFI=0.97, NNFI=0.96, RMSR= 0.022으로 나타났다. 분석결과 여대생의 자아존중감과 내적통제위는 건강상태지각 및 건강증진행위에 유의한 영향을 미치는 요인으로 확인되었으며, 여대생의 건강상태지각은 건강증진행위에 유의한 영향을 미치는 것으로 나타났다.

• Journal of Animal Science and Technology
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• v.45 no.5
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• pp.739-748
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• 2003

The objective of this study was to estimate genetic parameters for test-day milk production and somatic cell score using field data collected by dairy herd improvement program in Korea. Random regression animal models were applied to estimate genetic variances for milk production and somatic cell score. Heritabilities for milk yields, fat percentage, protein percentage, solid-not-fat percentage, and somatic cell score from test day records of 5,796 first lactation Holstein cows were estimated by REML algorithm in single trait random regression test-day animal models. For these analyses, Legendre polynomial covariate function was applied to model the fixed effect of age-season, the additive genetic effect and the permanent environment effect as random. Homogeneous residual variance was assumed to be equal throughout lactation. Heritabilities as a function of time were calculated from the estimated curve parameters from univariate analyses. Heritability estimates for milk yields were in range of 0.13 to 0.29 throughout first lactation. Heritability estimates for fat percentage, protein percentage and solid-not-fat percentage were within 0.09 to 0.11, 0.12 to 0.19 and 0.17 to 0.23, respectively. For somatic cell score, heritabilities were within 0.02 to 0.04. Heritabilities for milk productions and somatic cell score were fluctuated by days in milk with comparing 305d milk production.

• Journal of agricultural medicine and community health
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• v.26 no.1
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• pp.1-17
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• 2001

This study was conducted to investigate the role of drinking pattern in the relationship of alcohol consumption by face-to-face interview in rural elderly(n=994) aged 60~64 in Dalsung County, April to September in 1996. Pattern of alcohol drinking included drinking status, alcohol drinking at the morning without breakfast, average drinks per day, frequency of drinks per month, quantity of alcohol drinking, kind of preferred alcoholic beverage and duration of alcohol drinking. Blood pressure was measured once in each subject using a portable automatic sphygmomanometer. Difference in means of systolic blood pressure, alcohol drinking status, alcohol drinking at the morning without breakfast, and kind of alcoholic beverage were statistically significant before adjusting covariates, but alcohol drinking status and alcohol drinking at the morning without breakfast were statistically significant after adjusting covariates. And difference in means of diastolic blood pressure, kinds of alcoholic beverage was statistically significant before adjusting covariates, but no variables was significant after adjusting covariates. Model I multiple regression for systolic blood pressure that included average drinks per day as the variable of drink pattern, age, educational attainment and, previous history of cardiovascular disease were statistically significant, and multiple regression for diastolic blood pressure, educational attainment, BMI, and previous history of cardiovascular disease were statistically significant. Model II multiple regression for systolic blood pressure that included drinking patterns variables except average drinks per day, previous history of cardiovascular disease were statistically significant. However, multiple regression for diastolic blood pressure, no variables were significant. So, inconsistent with prior research, a positive relationship was not found between average drinks per day and diastolic and systolic blood pressure. The effect of alcohol drinking patterns on blood pressure has public health as well as clinical relevance. The study should be replicated to determine the reliability of our findings.

• Journal of Animal Science and Technology
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• v.48 no.1
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• pp.29-38
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• 2006

The objective of this study was to estimate genetic variances of growth curve parameters in Hanwoo cows. The data used in this study were records from 1,083 Hanwoo cows raised at Hanwoo Experiment Station, National Livestock Research Institute(NLRI). First evaluation model(Model I) fit year-season of birth and age of dam as fixed effects and second model(Model II) added age at the final weight as a linear covariate to Model I. Heritability estimates of A, b and k from Gompertz model were 0.22, 0.11 and 0.07 using modelⅠ and 0.28, 0.11 and 0.12 using modelⅡ. Those from Von Bertalanffy model were 0.22, 0.11 and 0.07 using modelⅠ, 0.28, 0.11 and 0.12 using modelⅡ. Heritability estimates of A, b and k from Logistic model were 0.14, 0.07 and 0.05 using modelⅠ, 0.18, 0.07 and 0.12 using modelⅡ. Heritability estimates of A from Gompertz model were higher than those from Von Bertalanffy model or Logistic model in both model Ⅰand model Ⅱ. Heritability estimates of b from Logistic model were higher than those from Gompertz model or Von Bertalanffy model in both modelⅠand model Ⅱ. Heritability estimates of birth weight, weaning weight, 3 month weight, 6 month weight, 9 month weight, 12 month weight, 18 month weight, 24 month weight, 36 month weight were after linear age adjustment 0.27, 0.11, 0.19, 0.14, 0.16, 0.23, 0.52 and 0.32, respectively. Heritability estimates of birth weight, weaning weight, 3 month weight, 6 month weight, 9 month weight and 24 month weight fit by Gompertz model were larger than those estimated from linearly adjusted data. Heritability estimates of 12 month weight, 18 month weight and 36 month weight fit by Von Bertalanffy model were larger than those estimated from linearly adjusted data. In the multitrait analyses for parameters from Gompertz model, genetic and phenotypic correlations between A and k parameters were －0.47 and －0.67 using modelⅠand －0.56 and －0.63 using model Ⅱ. Those between the A and b parameters were 0.69 and 0.34 using modelⅠand 0.72 and 0.37 using model Ⅱ. Those between the b and k parameters were －0.26 and 0.01 using modelⅠand －0.30 and 0.01 using model Ⅱ. In the multitrait analyses for parameters from Von Bertalanffy model, genetic and phenotypic correlations between A and k parameters were －0.49 and －0.67 suing model Ⅰ and －0.57 and －0.70 using modelⅡ. Those between the A and b parameters were 0.61 and 0.33 using modelⅠ and 0.60 and 0.30 using model Ⅱ. Those between the b and k parameters were －0.20 and 0.02 using modelⅠ and 0.16 and 0.00 using modelⅡ. In the multitrait analyses for parameters from Logistic model, genetic and phenotypic correlations between A and k parameters were －0.43 and －0.67 using model Ⅰ and －0.50 and －0.63 using modelⅡ. Those between the A and b parameters were 0.47 and 0.22 using modelⅠ and 0.38 and 0.24 using modelⅡ. Those between the b and k parameters were －0.09 and 0.02 using model Ⅰ and －0.02 and 0.13 using model Ⅱ.

• Journal of The Korean Association For Science Education
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• v.18 no.2
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• pp.173-182
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• 1998

This study investigated the influences of metacognitive learning strategies upon 6th-graders' achievement, science process skill, use of cognitive strategies, use of metacognitive strategies, self-efficacy, intrinsic value, attitude toward science class, and scientific attitude. The metacognitive learning strategies were developed on the basis of previous results and modified in a pilot study. Before the instructions, a pretest of motivation was administered, and used as a blocking variable. The score of previous achievement test was used as covariates for achievement and science process skill. Tests of use of cognitive strategies, use of metacognitive strategies, self-efficacy, intrinsic value, attitude toward science class, and scientific attitude were also administered, and their scores were used as covariates. After the instructions, a researcher-made achievement test, the Middle Grades Integrated Science Process Skills Test, and post-tests of above variables were administrated. Two-way ANCOVA results revealed that the scores of the treatment group were significantly higher than those of the control group for all tests except for science process skill. No interactions between the treatment and the level of the previous motivation were found. Educational implications are discussed.

• Korean Journal of Plant Taxonomy
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• v.37 no.3
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• pp.239-254
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• 2007

A comparative micromorphological study was examined on the leaves of the genus Glechoma and related genera (Nepetinae, Lamiaceae) by scanning electron microscopy (SEM) in order to evaluate their significance in the taxonomy. The leaves of taxa Marmoritis, Nepeta sect. Glechomanthe, G. hederacea var. longituba (Korea) are revealed amphistomatic type, while the remnants of taxa had hypostomatic type. The size range of the guard cells is $12.50-28.75{\times}9.17-21.25{\mu}m$: the smallest one was found in M. pharicus ($12.50-15.83{\times}9.17-11.25{\mu}m$), while the largest one was measured to G. hederacea var. longituba (Korea: $28.75-28.88{\times}21.25-21.38{\mu}m$). The stomatal type of genera Agastache, Dracocephalum was mostly diacytic, however for the rest rarely together with anisocytic and anomocytic, except G. hederaca var. longituba (Korea), Meehania urticifolia by having combined with diacytic and anomocytic. The shapes of epidermal cells are differ from in abaxial and adaxial side, and dived with two types (e.g., platelet, stripe pattern). Five types (three glandular, two non-glandular hairs) of trichomes are distributed in leaves. Among trichomes, long and stalk capitates glandular trichome, subsessile glands are different from studied taxa so that leaf micromorphological characters are significance features in the taxonomy.

• Journal of agriculture & life science
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• v.45 no.6
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• pp.109-114
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• 2011

The objective of this study was to investigate the effects of environments (farms born, testing groups, age at the tests, date at slaughter, ages at slaughter) on body weights at 6, 12, 18 and 24 months of ages, body type measurements at 18 months of age and carcass characteristics in Hanwoo steer populations that were collected from commercial farms and reared in a progeny testing station. Performances of a total of 1,838 steer calves set for tests from 2004 to 2008 were recorded. Carcass characteristics were the carcass grading results evaluated and data collected slaughter scores at 24 months of age. For growth traits of all age classes and body type traits measured at 18 months of age, farms born, test group and linear covariate of age at test were fit in the models. For carcass traits, date at slaughter and linear covariate of ages at slaughter were fit in the models. Effect of farm at birth was not significant for body weight at 24 months of age. Carcass weight, eye muscle area, yield score and back fat thickness were affected by dates at slaughter but not by the ages at slaughter. Marbling score, however, was affected by these two effects. Farms at birth did not seem to affect body type measures greatly. This study will be utilized for Hanwoo Steers genetic evaluation.

• Proceedings of the Korean Statistical Society Conference
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• 2002.11a
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• pp.287-292
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• 2002

최근 여러 분야에서 로지스틱 회귀에 대한 필요성과 그 응용이 급증하면서 이를 분석하기 위한 통계패키지가 많이 개발되어 사용되고 있다. 이 논문에서는 자료의 유형에 따라 활용할 수 있는 여러 형태의 로지스틱 회귀모형을 간단히 살펴보고, SPSS, SAS, STATA, MINITAB과 같은 통계패키지를 사용하여 로지스틱 회귀모형에 적용할 때 각각 다룰 수 있는 범위와 그 특징에 대해 다룬다.