• Annals of Occupational and Environmental Medicine
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• v.35
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• pp.26.1-26.15
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• 2023

Background: The objective of this study is to investigate the differences in incidence rates of targeted diseases by classification of occupations among construction workers in Korea. Methods: In a subject-based cohort of the Korean Construction Worker's Cohort, we surveyed a total of 1,027 construction workers. As occupational exposure, the classification of occupations was developed using two axes: construction business and job type. To analyze disease incidence, we linked survey data with National Health Insurance Service data. Eleven target disease categories with high prevalence or estimated work-relatedness among construction workers were evaluated in our study. The average incidence rates were calculated as cases per 1,000 person-years (PY). Results: Injury, poisoning, and certain other consequences of external causes had the highest incidence rate of 344.08 per 1,000 PY, followed by disease of the musculoskeletal system and connective tissue for 208.64 and diseases of the skin and subcutaneous tissue for 197.87 in our cohort. We especially found that chronic obstructive pulmonary disease was more common in construction painters, civil engineering welders, and civil engineering frame mold carpenters, asthma in construction painters, landscape, and construction water proofers, interstitial lung diseases in construction water proofers. Conclusions: This is the first study to systematically classify complex construction occupations in order to analyze occupational diseases in Korean construction workers. There were differences in disease incidences among construction workers based on the classification of occupations. It is necessary to develop customized occupational safety and health policies for high-risk occupations for each disease in the construction industry.

• Communications for Statistical Applications and Methods
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• v.25 no.5
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• pp.545-557
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• 2018

The inclusion of covariates in the model often affects not only the estimates of meaningful variables of interest but also its statistical significance. Such gap between statistical and subject-matter significance is a critical issue in huge sample studies. A popular huge sample study, the sample cohort data from Korean National Health Insurance Service, showed such gap of significance in the inference for the effect of obesity on cause of mortality, requiring careful consideration. In this regard, this paper proposes a sample size calibration method based on a Monte Carlo t (or z)-test approach without Monte Carlo simulation, and also proposes a test procedure for subject-matter significance using this calibration method in order to complement the deflated p-value in the huge sample size. Our calibration method shows no subject-matter significance of the obesity paradox regardless of race, sex, and age groups, unlike traditional statistical suggestions based on p-values.

• Proceedings of the Korean Statistical Society Conference
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• 2004.11a
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• pp.243-248
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• 2004

The timings of two successive events of interest may not be measurable, instead it may be right censored or interval censored; this data structure is called doubly censored data. In the study of HIV, two such events are the infection with HIV and the onset of AIDS. These data have been analyzed by authors under the assumption that infection time and induction time are independent. This paper investigates the regression problem when two events arc modeled to allow the presence of a possible relation between two events as well as a subject-specific effect. We derive the estimation procedure based on Goetghebeur and Ryan's (2000) piecewise exponential model and Gauss-Hermite integration is applied in the EM algorithm. Simulation studies are performed to investigate the small-sample properties and the method is applied to a set of doubly censored data from an AIDS cohort study.

• Korean Journal of Human Ecology
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• v.21 no.4
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• pp.629-647
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• 2012

This study explored what Korean college students, especially preservice teacher in early childhood education, experienced and how they constructed the meanings of experiences about their subject- matter course (early childhood mathematics education) taught in English. One cohort- 20 senior students- majoring in early childhood education in a 4-year university was participated in this study. Using action research method and narrative research method, data were analyzed. The findings were as follows: 1) preservice teacher experienced some difficulties to construrct professional knowledge through English. 2) They challenged to overcome these difficulties through active participation. 3) They got supports from instructor and peer group. 4) They accomplished the course with self-satisfaction. 5) They experienced the conflicts between social requirements and personal needs.

• Tuberculosis and Respiratory Diseases
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• v.63 no.5
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• pp.405-411
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• 2007

Background: The objective of this study was to evaluate the clinical applicability of the repeatability criteria recommended by the American Thoracic Society/European Respiratory Society (ATS/ERS) spirometry guidelines and to determine which factors affect the repeatability of spirometry in Korean adults. Methods: We reviewed the spirometry data of 4,663 Korean adults from the Korean National Health and Nutritional Examination Survey (KNHANES) Chronic Obstructive Pulmonary Disease Cohort (COPD cohort) and the Community-based Cohort Study VI-Fishing village/Islands (community cohort). We measured the anthropometric factors and differences between the highest and second-highest FVC (dFVC) and $FEV_1$ ($dFEV_1$) from prebronchodilator spirometry. Analyses included the distribution of dFVC and $dFEV_1$, comparison of the values meeting the 1994 ATS repeatability criteria with the values meeting the 2005 ATS/ERS repeatability criteria, and the performance of linear regression for evaluating the influence of subject characteristics and the change of criteria on the spiro-metric variability. Results: About 95% of subjects were able to reproduce FVC and $FEV_1$ within 150 ml. The KNHANES based on the 1994 ATS guidelines showed poorer repeatability than the COPD cohort and community cohort based on the 2005 ATS/ERS guidelines. Demographic and anthropometric factors had little effect on repeatability, explaining only 0.5 to 3%. Conclusion: We conclude that the new spirometry repeatability criteria recommended by the 2005 ATS/ERS guidelines is also applicable to Korean adults. The repeatability of spirometry depends little on individual characteristics when an experienced technician performs testing. Therefore, we suggest that sustained efforts for public awareness of new repeatability criteria, quality control of spirograms, and education of personnel are needed for reliable spirometric results.

• Korean Journal of Community Nutrition
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• v.8 no.4
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• pp.603-609
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• 2003

This study examined the reproducibility of nutrient intakes estimated by the 24-hour recall method in a prospective cohort study (Longitudinal study of aging and health monitoring of Korean elderly) of middle-aged volunteer subjects (42 males and 49 females) in the Seoul area. The three-day 24-hour recall was administered twice at an interval of approximately 6 months. The first data were collected and a corrective procedure was performed by interviewing of the subjects and a trained dietitian. The second data were collected by mail from the subjects without the performance of any corrective procedure. The mean age of the subjects was 53.5 $\pm$ 9.6 for the males and 52.2 $\pm$ 8.9 for the females. The subjects who had above college education were 95% in the case of the males and 60% in the case of the females. The characteristics of the male subjects in this study were that they were highly educated and held professional jobs and were from the middle or upper class. Comparing the first and second 24-hour recall data, the second data showed relatively lower intakes of all nutrients, except vitamin A, vitamin Bi and cholesterol. There was no difference in the nutrients of the first and the second data with respect to vitamin A, vitamin B$_1$ and cholesterol in the males and calcium, iron, sodium, vitamin A, vitamin B$_1$, vitamin B$_2$ and cholesterol in the females. This data may indicate that the 24 hour retail method without a dietitian's help may result in lower reporting of the subject's intakes. The men had a tendency to remember less than the women. Pearson's correlation coefficients with unadjusted nutrient intakes values were ranged from 0.24 to 0.66. When energy intake was adjusted, there was a slight increase (from 0.26 to 0.71). Intra-class correlation coefficients with nutrient-unadjusted values ranged from 0.22 to 0.66, and the energy-adjusted values were ranged from 0.23 to 0.69. The weighted Kappa statistical values ranged from 0.10 to 0.40. On the average,46.3% of the subjects who were found in the lowest quartile of the nutrient intake levels based on the first 24-hour recall, were in the lowest quartile based on the second 24-hour recall. Therefore, there was a low reproducibility between the first and the second 24-hour recall. We should examine the factors influencing low reproducibility. Also, strategies should be developed to maximize the reliability of the assessment, with regard to portion-size training and telephone validation. (Korean J Community Nutrition 8(4) : 603∼609, 2003)

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.7
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• pp.868-875
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• 2017

The aim of the present study was to investigate antioxidant nutrient intake and risk of metabolic syndrome based on stress level in rural Korean women. Subject were participants from the Multi-Rural Communities Cohort Study, which was a part of the Korean Genome and Epidemiology Study. According to scores of the Psychosocial Well-Being Index Short-Form, a total of 10,111 subjects were classified into 'low stress group (n=8,015)' from 0 to 26 points and 'high stress group (n=2,096)' above 27 points. Data were collected using self-administered questionnaires, anthropometric measurements, and blood chemical analysis. Dietary nutrient consumption was assessed by a semi-quantitative food frequency questionnaire. High stress group showed lower intake of antioxidant nutrients, such as vitamin A, vitamin C, vitamin E, folate, zinc, and carotene compared to the low stress group. Intake of fruits and vegetable was lower in the high stress group compared to the low stress group. Subjects with high stress showed higher risk of hypertension [odd ratio (OR), 95% confidence interval (CI)=1.226 (1.112~1.351)] and hypertriglyceridemia [OR, 95% CI=1.227 (1.110~1.356)] than subjects with low stress. High stress group had a significantly greater odds ratio for metabolic syndrome compared with the low stress group [OR, 95% CI=1.216 (1.101~1.342]). Thus, the present study suggests that high stress might be associated with low intake of antioxidant nutrients and high risk of metabolic syndrome in rural Korean women.