• Journal of Cancer Prevention
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• v.23 no.4
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• pp.183-190
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• 2018

Background: As the number of big-cohort studies increases, validation becomes increasingly more important. We aimed to validate administrative database categorized as colorectal cancer (CRC) by the International Classification of Disease (ICD) 10th code. Methods: Big-cohort was collected from Clinical Data Warehouse using ICD 10th codes from May 1, 2003 to November 30, 2016 at Seoul National University Bundang Hospital. The patients in the study group had been diagnosed with cancer and were recorded in the ICD 10th code of CRC by the National Health Insurance Service. Subjects with codes of inflammatory bowel disease or tuberculosis colitis were selected for the control group. For the accuracy of registered CRC codes (C18-21), the chart, imaging results, and pathologic findings were examined by two reviewers. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for CRC were calculated. Results: A total of 6,780 subjects with CRC and 1,899 control subjects were enrolled. Of these patients, 22 subjects did not have evidence of CRC by colonoscopy, computed tomography, magnetic resonance imaging, or positron emission tomography. The sensitivity and specificity of hospitalization data for identifying CRC were 100.00% and 98.86%, respectively. PPV and NPV were 99.68% and 100.00%, respectively. Conclusions: The big-cohort database using the ICD 10th code for CRC appears to be accurate.

• Journal of Preventive Medicine and Public Health
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• v.51 no.6
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• pp.281-288
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• 2018

Objectives: We investigated the association between cholecystectomy or appendectomy and the subsequent risk of colorectal cancer (CRC) in the Korean population. Methods: A retrospective cohort study was conducted with the National Health Insurance Service-National Sample Cohort of Korea; this sample was followed up from January 1, 2002, until the date of CRC incidence, loss to follow-up, or December 31, 2015. The exposure status of cholecystectomy and appendectomy was treated as a time-varying covariate. The calculated risk of CRC was stratified by follow-up period, and the association between these surgical procedures and CRC was investigated by a Cox regression model applying appropriate lag periods. Results: A total of 707 663 individuals were identified for analysis. The study population was followed up for an average of 13.66 years, and 4324 CRC cases were identified. The hazard ratio (HR) of CRC was elevated in the first year after cholecystectomy (HR, 1.71; 95% confidence interval [CI], 1.01 to 2.89) and in the first year and 2-3 years after appendectomy (HR, 4.22; 95% CI, 2.87 to 6.20; HR, 2.34; 95% CI, 1.36 to 4.03, respectively). The HRs of CRC after applying 1 year of lag after cholecystectomy and 3 years of lag after appendectomy were 0.80 (95% CI, 0.57 to 1.13) and 0.77 (95% CI, 0.51 to 1.16), respectively. Conclusions: The risk of CRC increased in the first year after cholecystectomy and appendectomy, implying the possibility of bias. When appropriate lag periods after surgery were applied, no association was found between cholecystectomy or appendectomy and CRC.

• Tuberculosis and Respiratory Diseases
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• v.82 no.4
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• pp.311-318
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• 2019

Background: Although physical activity is known to be beneficial to lung function, few studies have been conducted to investigate the correlation between physical activity and lung function in dusty areas. Therefore, the purpose of this study is to investigate the correlation between physical activity and lung function in a Korean cohort including normal and COPD-diagnosed participants. Methods: Data obtained from the COPD in dusty areas (CODA) cohort was analyzed for the following factors: lung function, symptoms, and information about physical activity. Information on physical activity was valuated using questionnaires, and participants were categorized into two groups: active and inactive. The evaluation of the mean lung function, modified Medical Research Council dyspnea grade scores, and COPD assessment test scores was done based on the participant physical activity using a general linear model after adjusting for age, sex, smoking status, pack-years, height, and weight. In addition, a stratification analysis was performed based on the smoking status and COPD. Results: Physical activity had a correlation with high forced expiratory volume in 1 second ($FEV_1$) among CODA cohort (p=0.03). While the active group exhibited significantly higher $FEV_1$ compared to one exhibited by the inactive group among past smokers (p=0.02), no such correlation existed among current smokers. There was no significant difference observed in lung function after it was stratified by COPD. Conclusion: This study established a positive correlation between regular physical activity in dusty areas and lung function in participants.

• Korean Journal of Radiology
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• v.23 no.9
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• pp.921-930
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• 2022

Objective: To identify epidermal growth factor receptor (EGFR) mutations in lung adenocarcinoma based on ¹⁸F-fluorodeoxyglucose (FDG) PET/CT radiomics and clinical features and to distinguish EGFR exon 19 deletion (19 del) and exon 21 L858R missense (21 L858R) mutations using FDG PET/CT radiomics. Materials and Methods: We retrospectively analyzed 179 patients with lung adenocarcinoma. They were randomly assigned to training (n = 125) and testing (n = 54) cohorts in a 7:3 ratio. A total of 2632 radiomics features were extracted from the tumor region of interest from the PET (1316) and CT (1316) images. Six PET/CT radiomics features that remained after the feature selection step were used to calculate the radiomics model score (rad-score). Subsequently, a combined clinical and radiomics model was constructed based on sex, smoking history, tumor diameter, and rad-score. The performance of the combined model in identifying EGFR mutations was assessed using a receiver operating characteristic (ROC) curve. Furthermore, in a subsample of 99 patients, a PET/CT radiomics model for distinguishing 19 del and 21 L858R EGFR mutational subtypes was established, and its performance was evaluated. Results: The area under the ROC curve (AUROC) and accuracy of the combined clinical and PET/CT radiomics models were 0.882 and 81.6%, respectively, in the training cohort and 0.837 and 74.1%, respectively, in the testing cohort. The AUROC and accuracy of the radiomics model for distinguishing between 19 del and 21 L858R EGFR mutational subtypes were 0.708 and 66.7%, respectively, in the training cohort and 0.652 and 56.7%, respectively, in the testing cohort. Conclusion: The combined clinical and PET/CT radiomics model could identify the EGFR mutational status in lung adenocarcinoma with moderate accuracy. However, distinguishing between EGFR 19 del and 21 L858R mutational subtypes was more challenging using PET/CT radiomics.

• Journal of the Korean housing association
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• v.22 no.1
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• pp.11-23
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• 2011

The purpose of this study is to explore cohort changes in first-time homeownership in Korea. The study collected qualitative data from individual interviews to explore the housing trajectories of different birth cohorts. As a result, Individual interviews facilitated an exploration of the decision making process of first-time homeowner with in a cohort context. The cohorts born in the 1950s seek a sense of security through homeownership, and have strong Korean sentiments of ownership. They tried various means to buy a house, and real estate market boom at that time played a role in the driving force. The cohorts born in the 1960s have less insecurity of tenure than the previous cohorts, but they still feel the need for homeownership. Since the currency crisis in 1997 caused the fluctuation of housing price, the 1960s cohort experienced a dramatic decline and rebound of assets while the previous cohorts had experienced a steady rise in housing prices. Finally, the attitude towards housing in the group of 1970s cohorts has changed from ownershiporiented to use-oriented.

• Journal of the Korean Society of Food Culture
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• v.19 no.1
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• pp.118-127
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• 2004

The purpose of this study was to identify the preferred types and consumption patterns of food away from home by socio-demographic factors including cohort groups, sex. and consumption patterns consisting of 6 types. Data were collected from 412 respondents by questionnaire method in April through May 2002. Regression results indicate that sex, age, family income, family type and size as well as the consumption patterns were significant in explaining the determinants of food away from home expenditures. Four logit function (each for Korean, American, Japanese, and bunsik) results showed that each type of food away from home was likely to vary depending on socio-demographic factors (i.e., cohort groups and sex) and the consumption patterns (i.e., convenience and simple, distinction and variety, tradition oriented, foreign design, health and quality oriented, sensible taste and mood). Similarities and differences in food away from home types are discussed, and future implications for food and nutrition specialists as well as food industrial marketers are provided.

• Journal of Korean Society of Rural Planning
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• v.25 no.4
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• pp.99-107
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• 2019

This paper analyzed the characteristics of population change from 2000 to 2018 in 466 mountainous areas using resident registration data from the Ministry of the Interior and Safety, and projected the population in those areas through 2050 with the cohort change ratio method. The population had dramatically decreased from 2000 to 2009. With the slowing population decrease after 2010, the population has increased gradually since 2014. Especially the population of ages over 65 in 2018 had increased 34% compared to 2000, while the working age population had decreased 29%. This shows that population aging becomes serious problems in the mountainous area. Assuming the cohort change ratios from 2010 to 2015 and child-woman ratio in 2015 remain constant, it appeared that the projected population of the mountainous area dropped to 1.26 million in 2030 and 820,000 in 2050. It is expected to have a population with an inverted pyramid structure showing a gender imbalance with more females in 60's and 70's. Although it continues to show the recent population growth in mountainous area, population in mountainous area is expected to consistently decrease. Therefore, it is required to develop policies and strategies to promote an influx of people into mountainous area for maintaining functionality and sustainability of mountainous areas.

• Journal of Korean society of Dental Hygiene
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• v.19 no.3
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• pp.409-419
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• 2019

Objectives: The purpose of this study was to analyze the factors affecting antibiotic prescription in dental outpatients. Methods: The present study was conducted using data from the National Health Insurance Service - National Sample Cohort. We analyzed prescriptions issued in the dental outpatient department in 2015, for adults over 19 years of age. Antibiotic prescription rates and mean prescription days were analyzed by sex, age, insurance type, presence of diabetes mellitus and hypertension, season in treatment, type of dental institution, and location of dental institution. Multivariate logistic regression was also performed to analyze the factors affecting antibiotic prescription in dental outpatients. Results: A total of 257,038 prescriptions were analyzed. The mean prescription days of antibiotics in dental outpatients were $3.04{\pm}1.08days$, and the prescription rate was 93.0%. Two variables (presence of diabetes mellitus and insurance type) were excluded from the multivariate logistic regression analysis model because they did not significantly affect antibiotic prescription. The possibility of antibiotic prescription was higher in men ${\geq}61years$ of age and those with hypertension. Furthermore, antibiotics were most frequently prescribed in dental clinics rather than dental hospitals, and more frequently in Busan compared to other areas (p<0.001). Conclusions: Several factors were determined to affect antibiotic prescription, and detailed guidelines for consistent antibiotic prescription are needed.

• Korean Journal of Social Welfare
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• v.60 no.2
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• pp.53-76
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• 2008

This study analyze the intergenerational transmission of poverty in Korea, using the first wave of Korea Welfare Panel Study. For this analysis, I produced poverty transition tables across generation and estimated logistic models to explore the effects of parent's poverty on the children's adulthood poverty. As the results, I found that parent's poverty reduced children's education level and then the low education level increased the likelihood that children experience poverty in their adulthood. In other words, parent's poverty might increase children's adulthood poverty through the mediating effects of education level. This mediating effects were also identified in the analyses by group and cohort. From the analyses by group, daughters rather than sons, those from urban rather than rural area, and the older cohort rather than younger cohort showed greater intergenerational transmission of poverty.

• Journal of the Korean Society of Clothing and Textiles
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• v.38 no.1
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• pp.33-45
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• 2014

This study investigates urban household consumption patterns for clothing items in different income cohorts through the analysis of an Almost Ideal Demand System (AIDS) model. Korea quarterly time-series statistics data for urban household expenditures from 1990 to 2013 analyzed household demand. The price and total consumption expenditure elasticities of 4 clothing items (outer wear, shoes, clothing related services and other miscellaneous clothing) for 7 income cohorts were estimated to investigate the clothing consumption patterns of different income cohorts. The study results show that the different household income cohorts have different consumption patterns for clothing items. The elastic demand of total consumption expenditures in the lowest household income cohort suggests that they consume clothing items as luxuries while other households mostly consume them as necessities. The price elasticity for all household income cohorts and clothing items (except the highest household income cohort and outer wear) was found to be elastic. The highest household income cohort had an inelastic price demand for all clothing items that implied a less sensitive clothing consumption change for the clothing price change than other households.