• 응용통계연구
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• 제30권2호
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• pp.203-213
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• 2017

우리는 이변량 경시적 자료의 조건부 결합 분포를 추정하기 위하여 회귀 모형과 코플라 모형을 연구하였다. 주변 분포의 추정을 위하여 시변 변환 모형을 고려하였고, 이변량 반응변수 각각에 대한 주변 분포를 가우시안 코플라를 이용하여 결합하여 조건부 결합 분포를 추정하였다. 우리가 제안한 모형은 조건부 평균 모형만으로 자료를 설명하기 어려운 경우에 적용될 수 있다. 시변 변환 모형과 가우시안 코플라 모형을 결합한 본 논문의 방법은 반복 측정된 이변량 경시적 자료에 대한 모형화가 용이하며 해석하기 쉬운 장점이 있다. 우리는 본 논문의 방법을 반복 측정된 이변량 콜레스테롤 자료를 분석하는데 적용하여 보았다.

• Journal of the Korean Data and Information Science Society
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• 제27권3호
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• pp.689-700
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• 2016

본 논문에서는 이변량 경시적 자료의 조건부 결합 분포를 추정하기 위하여 회귀 모형과 코플라 모형을 연구하였다. 주변 분포의 추정을 위하여 시변 전환 모형을 고려하였고, 이변량 반응변수 각각에 대한 주변 분포를 경험 분포를 이용한 비모수적 코플라를 이용하여 결합하여 조건부 결합 분포를 추정하였다. 주변 분포 모형의 모수 추정치는 추정방정식의 해로 얻어낼 수 있으며 우리가 제안한 모형은 조건부 평균 모형만으로 자료를 설명하기 어려운 경우에 적용될 수 있다. 시변 전환 모형과 비모수적 코플라 모형을 결합한 본 논문의 방법은 반복 측정된 이변량 경시적 자료에 대한 모형화가 모형에 대한 가정에서 비교적 자유로운 장점이 있다. 우리는 본 논문의 방법을 반복 측정된 이변량 콜레스테롤 자료를 분석하는데 적용하여 보았다.

• Communications for Statistical Applications and Methods
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• 제20권4호
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• pp.283-290
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• 2013

Subjects can experience two types of recurrent events in a longitudinal study. In addition, there may exist intermittent dropouts that results in repeated observation gaps during which no recurrent events are observed. Therefore, theses periods are regarded as non-risk status. In this paper, we consider a special case where information on the observation gap is incomplete, that is, the termination time of observation gap is not available while the starting time is known. For a statistical inference, incomplete termination time is incorporated in terms of interval-censored data and estimated with two approaches. A shared frailty effect is also employed for the association between two recurrent events. An EM algorithm is applied to recover unknown termination times as well as frailty effect. We apply the suggested method to young drivers' convictions data with several suspensions.

• 공학교육연구
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• 제23권1호
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• pp.26-36
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• 2020

This study aims to investigate the effect of college choice factors on withdrawal intention of first-year undergraduates in STEM majors. The data for this study were collected from a national sample of 4-year institutions that participated in Collegiate Longitudinal Study funded by the National Research Foundation of Korea during 2013-2014. The data included 1,484 students in STEM majors from 30 institutions, and this study used bivariate and multivariate analytic methods to answer the research questions. This study found that while the internal dimensions of college choice showed a negative effect on the intention to dropout, external dimensions of college choice such as college environment, financial accessibility, admission possibility had a positive effect on the intention. The findings indicate that it is necessary to pay attention to college choice for enrollment management to prevent first-year undergraduates in STEM majors from dropping out.

• Journal of Periodontal and Implant Science
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• 제47권2호
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• pp.96-105
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• 2017

Purpose: The National Health Insurance Service-National Sample Cohort and medical checkup data from 2002 to 2013 were used to evaluate the association between periodontal surgery for the treatment of periodontitis (PSTP) and vasculogenic erectile dysfunction (VED). Methods: Bivariate and multivariate logistic regression analyses were applied to a longitudinal retrospective database to assess the association between PSTP and VED while adjusting for the potential confounding effects of sociodemographic factors (age, household income, insurance status, health status, residence area, and smoking status) and comorbidities (diabetes mellitus, angina pectoris, cerebral infarction, and myocardial infarction). Results: Among the 7,148 PSTP within the 268,296 recruited subjects, the overall prevalence of VED in PSTP was 1.43% (n=102). The bivariate analysis showed that VED was significantly related to PSTP (odds ratio [OR], 1.99; 95% confidence interval [CI], 1.38-2.06; P<0.001), and this was confirmed in the multivariate analysis after adjusting for sociodemographic factors and comorbidities (OR, 1.29; 95% CI, 1.06-1.58; P=0.002). Conclusions: Subjects with a history of periodontal flap surgery had a significantly higher risk of VED, after adjusting for potential confounding factors. Further studies are required to identify the key mechanisms underlying the association between severe periodontal disease and VED.

• 성인간호학회지
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• 제26권6호
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• pp.621-629
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• 2014

Purpose: The purpose of this study was to investigate the nutritional support, gastric residual volume, and nutritional status of the intensive care unit (ICU) patients on enteral feeding. Methods: A descriptive longitudinal design was used to collect 5 day data on enteral nutrition of 52 ICU patients in an university hospital. Nutritional support was calculated with actual caloric intake compared to individual caloric requirement. Residual volumes were measured prior to routine feedings, and the serum albumin levels and the total lymphocyte counts were checked to evaluate nutritional status. The data were analyzed using one group repeated measures ANOVA, paired t-test, and Spearman's bivariate correlation analysis. Results: The subjects received their first enteral feeding on the $5.75^{th}$ day of ICU admission. The mean nutritional support rate was 49.1% of the requirement, however prescription rate and support rate were increased as time goes by. Gastric residual volumes were less than 10 cc in 95% cases. A significant negative correlation was found between nutritional support and nutritional status. Conclusion: The nutritional support for ICU patient was low compared to the requirement, and their nutritional status was worse than at the time of ICU admission. Further studies are necessary to develop nursing interventions for improving nutritional support for ICU patients.

• Journal of Preventive Medicine and Public Health
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• 제37권2호
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• pp.174-181
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• 2004

Objective : To examine the association between dietary factors and cognitive impairment in older Korean women living in the community. Methods : Wave 2 data, from the Suwon Longitudinal Aging Study (SLAS), of 365 women aged 65 years or over, were used. The Korean version of the 30-point Mini-Mental State Examination (MMSE-K) was used to assess cognitive impairment (score$\geq$19). Dietary habits and frequencies of food group consumption were also examined. Results : A total of 67 women (18.4%) were found to be cognitively impaired. In bivariate analyses, nondietary factors, such as age, marital status, education, income, self-rated health, depression, emotional support, social activity, exercise, and dietary factors, such as self-rated nutritional status, frequency of beans and bean products and milk and dairy products consumption were associated with cognitive impairment. In the multivariate analysis, a higher frequency ($\geq$1 vs. <1 time/day) of beans and bean products (OR=0.48, 95% CI: 0.23-0.99) and milk and dairy products (OR=0.25, 95% CI: 0.10-0.61) consumption was inversely associated with cognitive impairment, after adjustment for non-dietary factors. Conclusion : These results suggest that dietary factors may play a significant role in cognitive impairment of older Korean women.

• 한국사회복지학
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• 제67권3호
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• pp.281-303
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• 2015

본 연구는 남편과 아내의 은퇴가 상호의존적임을 파악한 연구로, 대다수가 비자발적으로 은퇴하는 경향을 고려하여 배우자의 자발적 은퇴와 비자발적 은퇴가 어떻게 영향을 미치는지 살펴보았다. 이를 위해 한국고령화연구패널 4차년도 응답자 중 노동경험이 있는 75세 이하의 부부 1,038쌍(2,076명)을 대상으로 프로빗분석과 다변량프로빗분석을 실시하였다. 분석 결과, 아내의 은퇴는 남편의 은퇴 결정에 유의미한 영향을 미치는 것으로 드러났다. 배우자의 비자발적 은퇴 역시 유의미한 영향요인으로 나타났는데, 60세 미만 집단에서 남편의 비자발적인 은퇴는 아내의 은퇴에 정적 영향을 미치나, 아내의 비자발적인 은퇴는 남편의 은퇴에 부적 영향을 미치는 것으로 나타났다. 이는 아내의 노동시장 지위가 남편에 종속되는 비율이 높고, 아내가 남편에 비하여 배우자의 건강문제로 은퇴하는 비율이 더 높은 기술통계와 맥을 같이 한다. 본 연구는 기존연구에서 다뤄지지 않은 부부의 상호의존적 영향을 확인하여, 향후 은퇴 연구와 고령자 노동정책에 시사점을 제공할 수 있을 것이다.

• 한국산업보건학회지
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• 제16권4호
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• pp.324-333
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• 2006

This study was designed to investigate the effect of bone demineralization and tibia lead on blood lead in retired lead workers. Two hundred thirty five(126 females and 109 males) retired lead workers who worked in 4 different lead factories and 101 non-occupationally lead exposed subjects(51 females and 51 males) were recruited from March 2004 to October 2004. Bone mineral density(BMD) was measured at left calcaneous bone area by broadband ultrasound attenuation(BUA) method with QUS-2(Metra Biosystems Inc, USA). The BUA value transformed into T-score by WHO standard conversion criteria. Tibia bone lead was measured for skeletal bone lead with K-xray fluorescence(K-XRF) and blood lead was analyzed with flameless atomic spectrophotometer. Hemoglobin, hematocrit, serum calcium and iron were also analyzed. In addition, information for smoking and drinking status and basic personal data such as age, gender and lead exposure were also collected using questionnaire inquiry. Blood lead was correlated with tibia lead (r=0.664) and these two variables were negatively correlated with BMD in bivariate analysis. BMD showed significant main effect on the change of blood lead independent to tibia lead without any effect modification of age or gender; the one T-score unit decrease of mineral bone density made $0.43{\mu}g/dl$ increase of blood lead. On the other hand, tibia lead showed effect modification with gender on blood lead; the slope of tibia lead on blood lead in male was steeper than in female and crossed at around zero of tibia lead. In the multiple regression analysis of blood lead and tibia lead on BMD after adjustment of related covariates, only blood lead showed statistically significant effect on BMD. This study confirmed that BMD and blood lead were significantly associated. To verify the causal association of BMD on blood lead and vice versa, further longitudinal studies are needed.

• 한국산업보건학회지
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• 제20권1호
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• pp.19-28
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• 2010

This study was designed to investigate the effect of increased blood and tibia lead on the change of bone mineral density in retired male lead workers. One hundred nine retired male lead workers who worked in 4 different lead industries and 51 nonoccupationally lead exposed male subjects were recruited from March 2004 to October 2004. Bone mineral density(BMD) was measured by broadband ultrasound attenuation(BUA) at left calcaneous bone area with broadband ultrasound attenuation method of QUS-2(Metra Biosystems Inc, USA). Tibia bone lead was measured for skeletal bone lead with K-xray fluorescence(K-XRF) and blood lead was analyzed with flameless atomic spectrophotometer. Hemoglobin, hematocrit, serum calcium and iron were also analyzed. In addition, information for smoking and drinking status and basic personal data such as age and lead exposure were also collected using questionnaire inquiry. Blood lead was correlated with tibia lead (r=0.711) and these two variables were negatively correlated with BUA in bivariate analysis. BUA and tibia lead showed significant main effects on the change of blood lead after adjusting covariates. The effect modification by the level of BMD (low: lower than the median of BUA and high: higher than the median of BUA) was observed between the association of tibia lead and blood lead after adjustment of covariates. The subjects who had higher BMD seemed to have lower blood lead by the increase of tibia lead than those of lower BMD. In the multiple regression analysis of blood lead and tibia lead on BUA after adjustment of covariates, only blood lead showed statistically significant effect on BUA. This study confirmed that BMD and blood lead were significantly associated. To verify the causal association of BMD on blood lead and vice versa, further longitudinal studies are needed.