• 응용통계연구
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• 제35권6호
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• pp.703-724
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• 2022

다변량 경시적 자료 분석은 반복 측정된 자료에 존재하는 상관관계를 올바르게 추정하면서 자료를 분석해야 한다. 경시적 연구에서는 다변량 경시적 자료가 주로 생성되지만, 기존 통계적 모형은 대부분 단변량으로 분석되어 다변량 경시적 자료에 존재하는 복잡한 상관관계를 제대로 설명하지 못하게 된다. 따라서 본 논문에서는 복잡한 상관관계를 설명하기 위해 공분산 행렬을 모형화하는 다양한 방법에 대해 고찰한다. 그 중 수정된 콜레스키 분해, 수정된 콜레스키 블록분해와 초구분해를 살펴본다. 그리고 일반화 자기회귀모수 행렬이 가지는 희박성 문제를 해결하기 위해 베이지안 방법을 이용하여 청소년 패널 데이터를 분석한다. 청소년 패널 데이터는 다변량 경시적 자료이며, 반응 변수로는 학교 적응도, 학업 성취도, 휴대전화 의존도를 고려한다. 자기 상관 구조와 혁신 표준 편차 구조를 달리 가정하여 여러 모형을 비교한다. 가장 적합한 모형에 대해 학교 적응도와 학업 성취도에 대해 모든 설명 변수가 유의미하며, 휴대전화 의존도가 반응 변수일 때 사교육 시간을 제외한 모든 설명 변수가 유의미한 것으로 나타난다.

• Nutrition Research and Practice
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• 제17권5호
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• pp.959-968
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• 2023

BACKGROUND/OBJECTIVES: Few studies have provided evidence of the association between diet quality and dental caries. This study aimed to examine the association between diet quality and untreated dental caries in a Korean representative population. SUBJECTS/METHODS: The study population included a sample of 13,815 participants, aged ≥ 19 from the Korea National Health and Nutrition Examination Survey during 2013-2015. The explanatory variable was diet quality and the outcome variable was untreated dental caries. Untreated dental caries were defined by the number of decayed teeth recorded according to the criteria established by the World Health Organization. Diet quality was defined by using the Korean Healthy Eating Index (KHEI) through the 24-h recall methods. We assessed the association between diet quality and untreated dental caries while adjusting for age, sex, education, income, smoking status, dental visits, toothbrushing frequencies, obesity, and diabetes mellitus. RESULTS: The mean overall KHEI scores in the untreated dental caries group were significantly lower than those in the group without untreated dental caries. Significant differences were observed in the untreated dental caries group based on the KHEI quartiles (P < 0.001). After adjusting for potential confounders, the quartiles of KHEI scores showed an association with untreated dental caries, demonstrating a dose-effect trend (odds ratio [OR], 1.57; 95% confidence interval [CI], 1.35-1.84 for 1st quartile; OR, 1.38; 95% CI, 1.19-1.59 for 2nd quartile; OR, 1.32; 95% CI, 1.14-1.53 for 3rd quartile; reference quartile highest]). CONCLUSIONS: The findings indicated an inverse association between diet quality and untreated dental caries in Korean adults. Healthcare providers should take into account the significant role of diet quality in preventing and managing oral health.

• 호스피스학술지
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• 제7권2호
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• pp.15-25
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• 2007

The purpose of this study was to survey the hospital staff's perception of hospice and death and thereby, suggest the ways to help them have a mature attitude towards and a better understanding of death through an effective education on hospice. For this purpose, this study was designed to provide some data useful for the hospital staff not experienced in facing the dying patients to handle the desperate situation skillfully and engage themselves more effectively in their hospice services. For this study, the researcher conducted a questionnaire survey for the staff of 'C' hospital in Seoul about their hospice philosophy, attitudes towards hospice and perception of death for the period from February, 2006 to March, 2006. A total of 751 subjects responded effectively to the survey. The data collected were analyzed using the SF55 11.0 for ANOVA and T-test in order to test the relationships among subjects' perception of death, their demographic variables, their health condition, their hospice philosophy formed from their experiences of patients' death and hospice services and their attitudes towards hospice. Besides, the correlations among their hospice philosophy, perception of death and attitudes towards hospice were tested. The results of this study can be summarized as follows; First, as a result of testing the relationships among subjects' experiences of health consulting. their experiences of patients' death and hospice and their hospice philosophy, it was confirmed that their experiences of health and death consulting and their experiences of having been educated were relevant. Second, it was found that such variables as health condition, death, experience of hospice and attitude towards hospice were not significantly correlated with each other. Third, as a consequence of testing the relationships among health condition, death, experience of hospice and perception of death, it was disclosed that only the physical health condition was significant. Fourth, it was confirmed that subjects' hospice philosophy, perception of death and attitudes towards hospice were at the usual level on average. Fifth, hospice philosophy, perception of death and attitudes towards hospice were found correlated significantly with each other. Sixth, as a result of the stepwise variable adjustment for such variables as hospice philosophy, perception of death, attitudes towards hospice, it was found that the adjusted r-square value was 0.347 when departments, experience of having been requested by dying patient for consulting, experience of having been educated on hospice, religion and marital status were set as independent variables. And the estimated value of each variable was found significant. Seventh, as a consequence of conducting the multiple regression analysis by setting 'religion' as significant independent variable, it was found that the estimated value of physical health condition was not significant statistically. This, as a result of the simple regression analysis for 'religion' only, its explanatory power was found .197, while its adjusted r-square value was 0.20. Eight, it was found that subjects' attitude towards hospice was significantly correlated with such variables of experience of patient's or relative's death, experience of having been requested for consulting about death, gender, marital status and departments. As a result of the multiple regression analysis and the subsequent stepwise adjustment for this variable, it was found that only 'experience of having been requested for consulting' had some explanatory power: its adjusted r-square value was 0.089. As discussed above, this study tested the correlations among various variables including hospital staff's attitude towards hospice and perception of death and thereby, provided for the data useful for their education on hospice. This study may be significant in that it proved that it would be essential to educate hospital staff on hospice for more effective care of hospice patients and their family members at hospital.

• 대한토목학회논문집
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• 제39권1호
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• pp.81-91
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• 2019

도시철도역사 이용자는 철도역 주변의 토지이용계획에 많은 영향을 받으나, 우리나라는 이와 관련된 연구는 미진한 상태로 토지이용계획에 상관없이 일률적으로 출입구 너비를 산정하여 일부 출입구에서는 대기행렬이 발생 하거나 이용자가 거의 없는 등 편차를 보인다. 따라서 본 연구에서는 도시철도역 출입구별 이용수요 추정 모형을 정립하고자 하며, 이를 위해 도시철도역 20개소를 대상으로 출입구별 이용수요, 토지이용면적, 사회경제지표 등을 철도역 중심으로 200 m, 500 m로 조사하여 다중회귀모형을 정립하였다. 모형의 종속변수(반응변수)를 1일, 첨두 1시간, 첨두 시간대 5분 동안의 철도역 방향별 유출입 이용수요로 설정하고, 철도역 반경 500 m, 200 m 범위의 토지용도(주거, 상업 업무, 공업, 교육, 공원) 면적과 사회경제지표(인구, 고용자, 종사자, 학생)를 독립변수(설명변수)로 설정하였다. 그 결과 도시철도 중심 반경 500 m 내 토지용도별 이용면적을 독립변수, 철도역 1일 유출입 이용수요를 종속변수로 사용하는 것이 모형의 적합도가 통계적으로 더 유의한 것으로 분석 되었다. 본 연구는 도시철도역의 이용자 및 교통약자의 이동 편의성 개선을 위해 도시철도 출입구 적정 규모 산정을 위한 기초 연구로 추후 교통약자 이용자 수를 반영하여 출입구별 이용자 수 추정, 교통약자 편의시설 적정 규모 산정 시 활용 가능할 것으로 보인다.

• 경영과정보연구
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• 제31권1호
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• pp.89-116
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• 2012

본 논문은 2001년부터 2010년의 표본기간 동안 상장된 제조업을 대상으로 Shyam-Sunder and Myers(1999) 그리고 Frank and Goyal(2003)의 목표조정모델과 자본조달순위모델에 기초하여 Chirinko and Singha(2000)의 비판적인 관점이 반영된 실증분석 논문이다. Shyam-Sunder and Myers(1999)의 모형을 통해 분석한 결과, 목표 조정계수는 0과 1 사이에 값을 가지며 설명력이 높고 유의한 변수인 반면에 자금 부족분 계수는 0에 가까워 자본조달이론을 지지 하기에는 작은 값을 가졌다. 또한 Frank and Goyal(2003)의 방법론을 사용하여 실증분석한 결과 자본조달순위이론은 지지되지 않았다.

• 산업진흥연구
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• 제5권3호
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• pp.31-36
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• 2020

본 연구는 호텔업, 숙박업 그리고 관광업에 종사하는 기업들의 자본구조가 어떤 요인들에 의해서 결정되는가를 탐색하기 위해 2000년부터 2019년까지 한국의 환대산업 기업들을 대상으로 실증적 분석을 하였다. 자본구조이론과 기존연구들에서 제시된 몇 가지 설명변수들을 이용하여 종속변수인 레버리지와의 회귀분석을 하였다. 표본기간 전체와 글로벌 금융위기라는 특수한 기간을 제외하고 그 이전과 이후로 구분하여 분석한 결과, 판매비용, 수익성 및 기업규모의 회귀계수가 각각 통계적으로 유의한 음(-)을 나타냈으며, 이 중에서 특히 기업규모의 계수는 제조기업을 대상으로 한 기존연구에서 보고된 정(+)의 관계와 정반대인 음(-)으로 나타나 환대산업의 특수성을 나타낸 것으로 추정된다.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.969-980
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• 2017

Galloping is one of the most serious vibration problems in transmission lines. Power lines can be extensively damaged owing to aerodynamic instabilities caused by ice accretion. In this study, the accident probability induced by galloping phenomenon was analyzed using logistic regression analysis. As former studies have generally concluded, main factors considered were local weather factors and physical factors of power delivery systems. Since the number of transmission towers outnumbers the number of weather observatories, interpolation of weather factors, Kriging to be more specific, has been conducted in prior to forming galloping accident estimation model. Physical factors have been provided by Korea Electric Power Corporation, however because of the large number of explanatory variables, variable selection has been conducted, leaving total 11 variables. Before forming estimation model, with 84 provided galloping cases, 840 non-galloped cases were chosen out of 13 billion cases. Prediction model for accidents by galloping has been formed with logistic regression model and validated with 4-fold validation method, corresponding AUC value of ROC curve has been used to assess the discrimination level of estimation models. As the result, logistic regression analysis effectively discriminated the power lines that experienced galloping accidents from those that did not.

• Journal of the Korean Data and Information Science Society
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• 제20권6호
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• pp.1093-1101
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• 2009

분위수 회귀모형은 확률변수들 사이에 확률적인 관계구조를 포함한 함수 모형을 좀 더 완벽하게 추정하도록 제공한다. 본 논문에서는 함수 추정에 로버스트하다고 알려져 있는 서포트벡터기계 기법과 이중벌칙커널기계를 이용하여 분위수 회귀모형을 추정하고자 한다. 이중벌칙커널기계는 고차원의 입력변수에 대한 분위수 회귀가 요구될 때 분위수 회귀모형을 잘 추정한다고 알려져 있다. 또한 본 논문에서는 광범위한 형태의 분위수 회귀모형 추정을 위해서 정규분포보다 비대칭 라플라스 분포를 이용한다. 본 논문에서 제안한 모형은 분위수 회귀모형 추정을 위해서 서포트벡터기계 기법에 이중벌칙커널기계를 이용하여 각각의 평균과 분산을 동시에 추정한다. 평균과 분산함수 추정을 위해 사용된 커널함수의 모수들은 최적의 값을 찾기 위해 일반화근사 교차타당성을 이용한다.

• 한국환경복원기술학회지
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• 제20권1호
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• pp.131-142
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• 2017

The function of urban parks as wildlife habitats is becoming increasingly important. The urban park serves as a key area for preserving urban biodiversity. The purpose of this study is to estimate the bird species diversity in 30 parks in Cheonan city and quantitatively analyze the influence of vegetation, park structure and landscape connectivity index. As the results, a total of 27 birds species and 1,509 individuals were found at the sites and the largest number of birds were found in the Cheongsa park with 17 species. The optimal regression model was selected as the explanatory variables for the logged park area (LPA), the tree cover ratio (Co_T) and the patch betweenness centrality (PB). LPA and Co_T mean the internal characteristics of the park, and PB was the external environmental variable meaning landscape connectivity. LPA was the most important factor (73.3%) as bird habitat, and the PB could be interpreted as a factor that should be considered as important (26.7%). It will be possible to consider these environmental variables in the park and green area construction and management.

• Journal of Nutrition and Health
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• 제28권7호
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• pp.644-652
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• 1995

The purpose of this study was to examine the relationship between sugar intake and behavioral problems in Korean school children. The subjects were 280 school children lived in Soung Nam city. Nutrient and sugar intakes were measured by 24-hour recall method and food frequency method through personal interview. Hyperactivity scores of children were measured by teacher and mother using conners Rating Scale-Revised. The average daily total sugar intake for the total sample was 63.0$\pm$37.4g(Range : 10g-220g). The result of stepwise multiple regression analysis using the sugar intake as dependent variable showed that energy, participation of school lunch program, Vit B2, protein, education of fathers, niacin, calcium are significant explanatory variables, explaining 44.8% of variation. As a result of the Conners scale test by teacher, 4% of children were Attention Deficit Hyperactivity Disorder(ADHD) children. A result of the Conners scale test by mother, 8% of children were ADHD children. The result of simple regression analysis had not shown significant relationship between sugar intake and ADHD scores. But the result of the Conners test by teacher, sugar intake(69.9$\pm$37.1g) of ADHD children were significantly higher than sugar intake(62.9$\pm$37.7g) of normal children(p<0.01).