• 대한예방의학회:학술대회논문집
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• 2003.04a
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• pp.30-37
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• 2003

o Cohort study became the major approach to study of chronic diseases such as CVD and cancer o Cohort can be population-based or volunteer-based o Types of be population-be categorized by source population and selection mechanism o More and more cohort studies involve biological specimens, such as blood, urine, toenail, cheek cells, etc. o Multi-center and multi-national collaboration is an effective way to increase sample size. o Current statistical method typically use time-to-event analysis by Cox proportional hazard model.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.9
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• pp.4677-4681
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• 2012

Objective: Egg consumption has been suggested to increase the risk of colorectal and some other cancers. The present study summarized and quantified the current evidence relating dietary intake of eggs and prostate cancer. Materials and methods: Literature searches were conducted to identify peer-reviewed manuscripts published up to July 2012. Twenty manuscripts from nine cohort studies and 11 case-control studies were identified. Summary risk estimates with 95% confidence intervals (CIs) were calculated for case-control and cohort studies separately. Results: Neither the case-control not the cohort studies showed any association of prostate cancer incidence with egg consumption (case-control studies: odds ratio 1.09, 95% CI 0.86-1.31; cohort studies: relative risk 0.97, 95% CI 0.97-1.07). The results were consistent in subgroup analysis. Furthermore, no association was observed between egg consumption and prostate cancer-specific mortality. Conclusions: Our analyses provided no evidence of a significant influence of egg consumption on prostate cancer incidence and mortality. However, more studies, particularly large prospective studies, are needed.

• Journal of Korean Society of Rural Planning
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• v.12 no.3 s.32
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• pp.39-42
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• 2006

The purpose of this study is to develop rural population model adapting cohort survival method with sift-share effects. Administrative district in this study is below Myun: about 2,000 population. Population data of rural area in 1990, 1995, and 2000 by age cohort were selected for applying developed model. Damping coefficient from population data was calculated as 7% and results applying this coefficient in rural population data below the error from 12% to 1.06%. In detail, most of cohorts fitted with developed model except from 15 to 29 age groups. Application result of small population area; DaesulMyun revealed that main factor of population change is not natural change but migration.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.3
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• pp.813-820
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• 2015

In recent years, there has been an argument that the academic performance of college students taught in English might be lower than those exposed in Korean under ceteris paribus environment. This paper examined the validity of this argument against the effectiveness of teaching-in-English, using student data from investment courses at a leading national university in Busan. Of a total of 165 students, 77 students took the teaching-in-Korean class (cohort A), whereas 88 students registered for the teaching-in-English class (cohort B). The findings did not support the popular argument. There was no significant difference in academic performance between student cohort A and student cohort B.

• Speech Sciences
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• v.9 no.2
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• pp.135-146
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• 2002

Generally a speaker verification system improves its system recognition ratio by regularizing log likelihood ratio, using a speaker model and its background speaker model that are required to be verified. The speaker-based cohort method is one of the methods that are widely used for selecting background speaker model. Recently, Gaussian-based cohort model has been suggested as a virtually synthesized cohort model, and unlike a speaker-based model, this is the method that chooses only the probability distributions close to basic speaker's probability distribution among the several neighboring speakers' probability distributions and thereby synthesizes a new virtual speaker model. It shows more excellent results than the existing speaker-based method. This study compared the existing speaker-based background speaker models and virtual speaker models and then constructed new virtual background speaker model groups which combined them in a certain ratio. For this, this study constructed a speaker verification system that uses GMM (Gaussin Mixture Model), and found that the suggested method of selecting virtual background speaker model shows more improved performance.

• Safety and Health at Work
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• v.8 no.2
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• pp.169-174
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• 2017

Background: We assessed the cancer risks of four different Finnish asbestos-exposed cohorts. We also explored if the cohorts with varying profiles of asbestos exposure exhibited varying relative risks of cancer. Methods: The incident cancer cases for the asbestos-exposed worker cohorts were updated to the end of 2012 using the files of the Finnish Cancer Registry. The previously formed cohorts consisted of asbestos mine workers, asbestosis patients, asbestos sprayers, and workers who had taken part in a screening study based on asbestos exposure at work. Results: The standardized incidence ratio (SIR) for mesothelioma varied from about threefold to > 100-fold in the different cohorts. In the screening cohort the SIR for mesothelioma was highest in 2003-2007, In other cohorts it was more constant in 5-year period inspection. The SIR for lung cancer was about twofold to tenfold in all except the screening cohort. Asbestos sprayers were at the highest risk of mesothelioma and lung cancer. Conclusion: The SIR for mesothelioma is high in all of the cohorts that represent different kinds of asbestos exposure. The smaller SIR for mesothelioma in the screening cohort with lowest level of asbestos exposure might suggest dose-responsiveness between asbestos exposure and mesothelioma. It does seem that the highest risk of lung cancer in these cohorts except in the youngest of the cohorts, the screening cohort, is over. The highest SIR for lung cancer of the asbestosis patient and sprayers cohort is explained by their heavy asbestos exposure.

• Journal of Preventive Medicine and Public Health
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• v.53 no.5
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• pp.313-322
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• 2020

Objectives: This study was conducted to determine the incidence and risk factors of myocardial infarction (MI) and stroke in farmers compared to the general population and to establish 5-year prediction models. Methods: The farmer cohort and the control cohort were generated using the customized database of the National Health Insurance Service of Korea database and the National Sample Cohort, respectively. The participants were followed from the day of the index general health examination until the events of MI, stroke, or death (up to 5 years). Results: In total, 734 744 participants from the farmer cohort and 238 311 from the control cohort aged between 40 and 70 were included. The age-adjusted incidence of MI was 0.766 and 0.585 per 1000 person-years in the farmer and control cohorts, respectively. That of stroke was 0.559 and 0.321 per 1000 person-years in both cohorts, respectively. In farmers, the risk factors for MI included male sex, age, personal history of hypertension, diabetes, current smoking, creatinine, metabolic syndrome components (blood pressure, triglycerides, and high-density lipoprotein cholesterol). Those for stroke included male sex, age, personal history of hypertension, diabetes, current smoking, high γ-glutamyl transferase, and metabolic syndrome components (blood pressure, triglycerides, and high-density lipoprotein cholesterol). The prediction model showed an area under the receiver operating characteristic curve of 0.735 and 0.760 for MI and stroke, respectively, in the farmer cohort. Conclusions: Farmers had a higher age-adjusted incidence of MI and stroke. They also showed distinct patterns in cardiovascular risk factors compared to the general population.

• Safety and Health at Work
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• v.11 no.2
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• pp.173-177
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• 2020

Background: Indoor air dampness microbiota (DM) is a big health hazard. Sufficient evidence exists that exposure to DM causes new asthma or exacerbation, dyspnea, infections of upper airways and allergic alveolitis. Less convincing evidence has yet been published for extrapulmonary manifestations of dampness and mold hypersensitivity syndrome). Methods: We investigated the prevalence of extrapulmonary in addition to respiratory symptoms with a questionnaire in a cohort of nurses and midwives (n = 90) exposed to DM in a Helsinki Obstetric Hospital. The corresponding prevalence was compared with an unexposed cohort (n = 45). Particular interest was put on neurological symptoms and multiple chemical sensitivity. Results: The results show that respiratory symptoms were more common among participants of the study vs. control cohort, that is, 80 vs 29%, respectively (risk ratio [RR]: 2.56, p < 0.001). Symptoms of the central or peripheral nervous system were also more common in study vs. control cohort: 81 vs 11% (RR: 6.63, p < 0.001). Fatigue was reported in 77 vs. 24%, (RR: 3.05, p < 0.001) and multiple chemical sensitivity in 40 vs. 9%, (RR: 3.44, p = 0.01), the so-called "brain fog", was prevalent in 62 vs 11% (RR: 4.94, p < 0.001), arrhythmias were reported in 57 vs. 2.4% (RR: 19.75, p < 0.001) and musculoskeletal pain in 51 vs 22% (RR: 2.02, p = 0.02) among participants of the study vs. control cohort, respectively. Conclusion: The results indicate that the exposure to DM is associated with a plethora of extrapulmonary symptoms. Presented data corroborate our recent reports on the health effects of moist and mold exposure in a workplace.

• The Korean Journal of Applied Statistics
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• v.30 no.1
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• pp.13-24
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• 2017

The Sample Cohort DB supplied by the National Health Insurance Service is a valuable resource for statistical studies as well as for health and medical studies. It takes significant time and effort to extract data from this Cohort DB having a large size. As such, we introduce a database system, conveniently called the National Health Insurance Service Cohort DB Extract Tool (NICE Tool), which supports several useful operations for effectively and efficiently managing the Cohort DB. For example, researchers can extract variables and cases related with study by simply clicking a computer mouse without any prior knowledge regarding SAS DATA step or SQL. We expect that NICE Tool will facilitate the faster extraction of data and eventually lead to the active use of the Cohort DB for research purposes.

• Annals of Geriatric Medicine and Research
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• v.20 no.3
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• pp.114-117
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• 2016

A research project, the "Construction of Frailty Cohort for Elderly and Intervention Study," funded by the Ministry of Health and Welfare, has been ongoing since December 2015. The Korean Frailty and Aging Cohort Study (KFACS) aims to identify risk factors for adverse outcomes associated with frailty in community-dwelling older adults, as well as means of prevention. KFACS is a multicenter, longitudinal study, with the baseline survey being conducted in 2016-2017. The sample (n=3,000) consists of those aged 70-84 years, stratified by age and gender, recruited from urban and rural regions nationwide. An in-person interview and health examination are performed every 2 years. This project is also conducting many intervention studies. Project interventions focus on nutrition and exercise. The nutritional intervention study compares the effects of 1.2 g/kg versus 1.5 g/kg daily protein intake on sarcopenia and frailty in older Koreans. The exercise trial examines the effectiveness of an information and communication technology-based program in preventing or reducing frailty.