• 한국대기환경학회지
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• 제30권3호
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• pp.281-290
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• 2014

This study was conducted to evaluate the distribution characteristics of $PM_{10}$ and heavy metals concentrations in the ambient air of Gyeonggi-do area by region and season from February, 2013 to March, 2014. The regression model for the prediction of formation characteristics and contamination degree of $PM_{10}$ and heavy metals by correlation analysis and regression analysis for using the multivariate statistical analysis was also established. The main wind direction during the investigation period was South East (SE) and West South West (WSW) winds, and the concentration of $SO_2$ at Ansan with industrial region showed 1.6 times higher than Suwon, Euiwang with residential region. The concentrations (median) of Pb, Cu and Ni at Ansan showed 3.2~4.5, 1.9~2.2 and 1.7~2.6 times respectively higher than those at Suwon. By the seasonal concentration variation, the concentrations of $PM_{10}$, Pb, Fe and As in winter and spring (December to May) showed 1.7, 1.9, 1.9 and 2.7 times respectively higher than those in summer and fall (June to November). As, Fe and $PM_{10}$ had a big difference by the seasonal factors, and Cu and Ni were evaluated to be influenced by the regional factors. From the results of correlation analysis among the target items, the correlation coefficient of PM and Mn had 0.82 (p/0.01) and that of Fe and Mn had 0.82 (p/0.01), which showed high correlation. And the correlation coefficients for $SO_2$ and Pb, CO and $PM_{10}$ were 0.66 (p/0.01) and 0.62 (p/0.01) respectively. The multiple linear regression models for $PM_{10}$, Pb, Cu, Cr, As, Ni, Fe and Mn were established by independent variables of CO, $SO_2$ and meteorological factors (wind speed, relative humidity). In the regression models, independent variable $SO_2$ was in cause-and-effect relationship with all dependent variables, and $PM_{10}$, Fe and Mn were influenced by CO and wind speed, and Pb, Cu, Ni and As had a main factor of $SO_2$.

• Tuberculosis and Respiratory Diseases
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• 제80권4호
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• pp.385-391
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• 2017

Background: Men with chronic obstructive pulmonary disease, have reduced endogenous testosterone levels, but the relationship between pulmonary function and endogenous testosterone levels, is inconsistent. Testicular volume is a known indicator of endogenous testosterone levels, male fertility, and male potency. In the present study, the authors investigated the relationship, between testicular volume and lung function. Methods: One hundred and eighty-one South Korean men age 40-70, hospitalized for urological surgery, were retrospectively enrolled, irrespective of the presence of respiratory disease. Study subjects underwent pulmonary function testing, prior to procedures, and testicular volumes were measured by orchidometry. Testosterone levels of patients in blood samples collected between $7{\small{AM}}$ and $11{\small{AM}}$, were measured by a direct chemiluminescent immunoassay. Results: The 181 study subjects were divided into two groups, by testicular volume (${\geq}35mL$ vs. <35 mL), the larger testes group, had better lung functions (forced vital capacity [FVC]: $3.87{\pm}0.65L$ vs. $3.66{\pm}0.65L$, p=0.037; forced expiratory volume in 1 second [$FEV_1$]: $2.92{\pm}0.57L$ vs. $2.65{\pm}0.61L$, p=0.002; FVC % predicted: $98.2{\pm}15.2%$ vs. $93.8{\pm}13.1%$, p=0.040; $FEV_1$ % predicted: $105.4{\pm}19.5%$ vs. $95.9{\pm}21.2%$, p=0.002). In addition, the proportion of patients with a $FEV_1/FVC$ of <70%, was lower in the larger testes group. Univariate analysis conducted using linear regression models, revealed that testicular volume was correlated with FVC (r=0.162, p=0.029), $FEV_1$ (r=0.218, p=0.003), $FEV_1/FVC$ (r=0.149, p=0.046), and $FEV_1$ % predicted (r=0.178, p=0.017), and multivariate analysis using linear regression models, revealed that testicular volume was a significant predictive factor for $FEV_1$ % predicted (${\beta}=0.159$, p=0.041). Conclusion: Larger testicular volume was independently associated, with favorable indices of lung function. These results suggest that androgens, may contribute to better lung function.

• 대한원격탐사학회지
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• 제15권2호
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• pp.147-158
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• 1999

지표면에 대한 다양한 정보를 제공해 주는 원격탐사기법은 수 십년 동안 우리의 환경을 관찰하고 이해하는데 중요한 역할을 해왔다. 이러한 원격탐사 자료를 이용하는데 다양한 디지털 영상처리기법이 도입되어 자료에서 관찰되는 여러 가지 특성을 모형화하고 처리하는데 매우 유용하게 활용되어져 왔다. 화소들 간의 공간적 관계를 고려하는 Markov Random Field (MRF) 모형은 텍스처 모델링이나 영상분할 및 분류와 같은 여러 분야에서 많이 이용되는 모형으로 이것에 기초한 다양한 알고리즘이 발표되었다. 보통 원격탐사 자료는 그 크기가 매우 크고 시간적 간격을 두고 변화를 관측해 가는 경우에는 분석해야할 자료의 양이 매우 방대하다. 이러한 자료를 처리하는데 걸리는 시간은 처리해야할 자료의 양과는 비선형적 관계에 있다. 본 논문에서는 MRF를 이용하여 원격탐사 자료를 처리할 때 걸리는 시간을 단축하기 위한 방법론이 연구되었다. 이를 위해 논리적 구조로 영상을 피라미드형태로 감소하는 크기로 분석하는 multiresolution 구조가 고려되었는데 이는 연상의 거시적 특징과 미세한 특징을 효율적으로 분석할 수 있는 방법을 제공해 준다. 영상의 크기가 커질수록 파라미터 추정 또한 복잡하고 많은 시간을 요하게 된다. 본 논문에서는 이를 위해 Bayesian 방법을 이용하여 원격탐사 영상과 같은 크기가 큰 영상의 MRF 모형의 파라미터를 효율적으로 추정할 수 있는 방법에 제안되어 있다.

• Nutrition Research and Practice
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• 제5권4호
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• pp.357-364
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• 2011

Selenium is an antioxidant trace element linked to cardiovascular disease and cancer. Although diet is a major source, relatively little else is known about independent determinants of selenium levels in free-living humans. In this study, we aimed to investigate the independent demographic. lifestyle, and dietary determinants of selenium levels in 1,997 men and 1,905 women in two large prospective U.S. cohorts. Toenail selenium levels were quantified using neutron activation analysis. Diet, geographic residence, demographic, and environmental factors were assessed by validated self-administered questionnaires. Multivariate generalized linear models were conducted to assess the independent relations of these factors with toenail selenium levels, correcting for measurement error in the diet. In multi variable-adjusted analyses, independent predictors of higher selenium were male gender (6.3% higher levels); living in West and Northern-Midwest U.S. regions (8.9% and 7.4% higher than Southern-Midwest regions, respectively); consumption of beef and bread products (between 0.7 - 2.5% higher per daily serving); and selenium supplement use (6.9% higher than non-users); whereas cigarette smoking (5-10% lower than never smokers), older age (0.6% lower per 5 years), and consumption of eggs, white rice, dairy products, coffee, and alcohol (between 0.1 to 2.0% lower per daily serving) were associated with lower selenium. Multiple dietary and non-dietary factors independently predicted selenium levels, suggesting that both consumption and non-dietary processes (e.g.. related to oxidant status) may affect levels. Significant geographic variation in selenium levels exists in the US.

• Nutrition Research and Practice
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• 제12권5호
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• pp.443-448
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• 2018

BACKGROUND/OBJECTIVES: This study was conducted to investigate the effects of sodium-potassium ratio on insulin resistance and sensitivity in Korean adults. SUBJECTS/METHODS: Subjects were 3,722 adults (1,632 men and 2,090 women) aged 40-69 years participating in the Korean genome and epidemiology study_Ansan and Ansung study. Insulin resistance was assessed using homeostasis model assessment of insulin resistance (HoMA-IR) and fasting insulin, and insulin sensitivity was assessed by using the quantitative insulin sensitivity check index (QUICKI). The 24-h urinary sodium and potassium excretion were estimated from spot urinary samples using the Tanaka formula. The generalized linear model was applied to determine the association between urinary sodium-potassium ratio and insulin resistance. RESULTS: HoMA-IR (P-value = 0.029, P-trend = 0.008) and fasting insulin (P-value = 0.017, P-trend = 0.005) levels were positively associated with 24-h estimated urinary sodium-potassium ratio in the multivariable model. QUICKI was inversely associated with 24-h estimated urinary sodium-potassium ratio in all models (P-value = 0.0002, P-trend < 0.0001 in the multivariate model). CONCLUSION: The present study suggests that high sodium-potassium ratio is related to high insulin resistance and low insulin sensitivity. Decreasing sodium intake and increasing potassium intake are important for maintaining insulin sensitivity. Further studies are needed to confirm these findings in longitudinal studies.

• Journal of Preventive Medicine and Public Health
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• 제54권1호
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• pp.37-45
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• 2021

Objectives: Bisphenol A (BPA) is used in the electrical, mechanical, medical, and food industries. Previous studies have suggested that BPA is an endocrine disruptor. Regulation of BPA has led to increased use of bisphenol F (BPF) and bisphenol S (BPS). However, few studies have investigated the associations of BPF and BPS with thyroid dysfunction in children. Our study investigated the associations of prenatal BPA and early childhood BPA, BPF, and BPS exposure with thyroid function in 6-year-old children. Methods: Prenatal BPA concentrations were measured during the second trimester of pregnancy in an established prospective birth cohort. We measured urinary BPA, BPF, and BPS concentrations and thyroid hormone levels (thyroid-stimulating hormone, total T3, and free T4) in 6-year-old children (n=574). We examined the associations between urinary bisphenol concentrations and percentage change of thyroid hormone concentrations using multivariate linear regression. We also compared thyroid hormone levels by dividing the cohort according to BPA, BPF, and BPS concentrations. Results: The associations between prenatal BPA and total T3 levels were statistically significant in all models, except for girls when using a crude model. The associations between urinary BPA and BPS concentrations and levels of all thyroid hormones were not statistically significant. However, we observed that lower free T4 levels (-1.94%; 95% confidence interval, -3.82 to -0.03) were associated with higher urinary BPF concentrations in girls only. Conclusions: Our findings identified significant associations between prenatal BPA exposure and total T3 levels in all children and between BPF exposure and free T4 levels in girls only.

• Steel and Composite Structures
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• 제45권3호
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• pp.389-408
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• 2022

Residual capacity is defined as the load carrying capacity of an RC column after undergoing severe damage. Evaluation of residual capacity of RC columns is necessary to avoid damage initiation in RC structures. The central aspect of the current research is to propose an empirical formula to estimate the residual capacity of RC columns after undergoing severe damage. This formula facilitates decision making of whether a replacement or a repair of the damaged column is adequate for further use. Available literature mainly focused on the simulation of explosion loads by using simplified pressure time histories to develop residual capacity of RC columns and rarely simulated the actual explosive. Therefore, there is a gap in the literature concerning general relation between blast damage of columns with different explosive loading conditions for a reliable and quick evaluation of column behavior subjected to blast loading. In this paper, the Arbitrary Lagrangian Eulerian (ALE) technique is implemented to simulate high fidelity blast pressure propagations. LS-DYNA software is utilized to solve the finite element (FE) model. The FE model is validated against the practical blast tests, and outcomes are in good agreement with test results. Multivariate linear regression (MLR) method is utilized to derive an analytical formula. The analytical formula predicts the residual capacity of RC columns as functions of structural element parameters. Based on intensive numerical simulation data, it is found that column depth, longitudinal reinforcement ratio, concrete strength and column width have significant effects on the residual axial load carrying capacity of reinforced concrete column under blast loads. Increasing column depth and longitudinal reinforcement ratio that provides better confinement to concrete are very effective in the residual capacity of RC column subjected to blast loads. Data obtained with this study can broaden the knowledge of structural response to blast and improve FE models to simulate the blast performance of concrete structures.

• 대한원격탐사학회지
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• 제37권6_1호
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• pp.1739-1756
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• 2021

대기 중 이산화질소(NO₂)는 주로 인위적인 배출요인으로 발생하며 화학 반응을 통해 이차오염 물질 및 오존 형성에 매개 역할을 하는 인체 건강에 악영향을 미치는 물질이다. 우리나라는 지상 관측소에 의한 실시간 NO₂ 모니터링을 수행하고 있지만, 이는 점 기반의 관측 값으로써 미관측 지역의 공간 분포 분석이 어렵다는 한계점을 지닌다. 본 연구에서는 선형 회귀 기반 모델인 다중 선형 회귀와 회귀 크리깅, 기계학습 알고리즘인 Random Forest (RF), Support Vector Regression (SVR)을 적용한 공간 내삽 모델링을 통해 서울 지역의 지상 NO₂ 농도 지도를 제작하였고, 일별 Leave-One-Out Cross Validation (LOOCV) 교차 검증을 시행하였다. 2020년 연구기간 내 일별 LOOCV에서 MLR, RK, SVR 모델의 일별 평균 Index of agreement (IOA)는 약 0.57로 유사한 성능을 보였으며, RF (0.50)보다 높은 성능이 확인되었다. RK의 일별 평균 nRMSE는 0.9483%으로 MLR (0.9501%)보다 상대적으로 낮은 오차를 나타냈다. MLR과 RK, RF 모델의 계절별 공간 분포는 비슷한 양상을 보였으며, RF는 다른 모델에 비해 좁은 NO₂ 농도 범위가 확인되었다. 본 연구에서 제안된 선형 회귀 기반 공간 내삽은 지상 NO₂ 뿐 아니라 다른 대기 오염 물질의 도시 지역 공간 내삽을 위해 활용 가능성이 높을 것으로 기대된다.

• Asian Pacific Journal of Cancer Prevention
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• 제15권20호
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• pp.8607-8612
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• 2014

Background: Breast cancer patients experience a variety of altered appearance - such as loss or disfigurement of breasts, discolored skin, and hair loss - which result in psychological distress that affect their quality of life. This study aims to evaluate the impact of socioeconomic status on the altered appearance distress, body image, and quality of life among Korean breast cancer patients. Materials and Methods: A cross-sectional survey was conducted at advocacy events held at 16 different hospitals in Korea. Subjects were eligible to participate if they were 18 years of age or older, had a histologically confirmed diagnosis of breast cancer, had no evidence of recurrence or metastasis, and had no psychological problems at the time of the survey. Employment status, marital status, education, and income were assessed for patient socioeconomic status. Altered appearance distress was measured using the NCI's cancer treatment side effects scale; body image and quality of life were measured by the EORTC QLC-C30 and BR23. Means and standard deviations of each outcome were compared by socioeconomic status and multivariate linear regression models for evaluating the association between socioeconomic status and altered appearance distress, body image, and quality of life. Results: A total of 126 breast cancer patients participated in the study; the mean age of participants was 47.7 (SD=8.4). Of the total, 83.2% were married, 85.6% received more than high school education, 35.2% were employed, and 41% had more than $3000 in monthly household income. About 46% had mastectomy, and over 30% were receiving either chemotherapy or radiation therapy at the time of the survey. With fully adjusted models, the employed patients had significantly higher altered appearance distress (1.80 vs 1.48; p<0.05) and poorer body image (36.63 vs 51.69; p<0.05) compared to the patients who were unemployed. Higher education (10.58, standard error (SE)=7.63) and family income (12.88, SE=5.08) was positively associated with better body image after adjusting for age, disease stage at diagnosis, current treatment status, and breast surgery type. Similarly, patients who were married and who had higher education had better quality of life were statistically significant in the multivariate models. Conclusions: Socioeconomic status is significantly associated with altered appearance distress, body image, and quality of life in Korean women with breast cancer. Patients who suffer from altered appearance distress or lower body image are much more likely to experience psychosocial, physical, and functional problems than women who do not, therefore health care providers should be aware of the changes and distresses that these breast cancer patients go through and provide specific information and psychosocial support to socioeconomically more vulnerable patients.

• Safety and Health at Work
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• 제4권1호
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• pp.27-36
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• 2013

Objectives: Mental health has been shown to be linked with certain underlying physiological mechanisms. The objective of this cross sectional study was to investigate the relationship between depressive symptoms and brachial artery reactivity (BAR) in an understudied population: police officers. Methods: Participants were 351 police officers who were clinically examined in the Buffalo Cardio-Metabolic Police Stress (BCOPS) study. BAR was performed using standard B-Mode ultrasound procedures. Depressive symptoms were measured using the Center for Epidemiological Studies Depression (CES-D) scale. Mean values of the difference between the baseline and maximum diameters of the brachial artery were determined across three categories of CES-D score using the analysis of variance and the analysis of covariance. p-values for linear trends were obtained from linear regression models. Results: The mean age (${\pm}$ standard deviation) of all officers was $40.9{\pm}7.2$ years. Women had a slightly higher mean CES-D score than men ($8.9{\pm}8.9$ vs. $7.4{\pm}6.4$) and a slightly higher percentage increase of BAR than men (6.90 vs. 5.26%). Smoking status significantly modified the associations between depressive symptoms and BAR. Among current smokers, mean absolute values of BAR significantly decreased as depressive symptoms increased after adjustment for age, gender, race/ethnicity, hypertension, and diabetes; the multivariate-adjusted p-values were 0.033 (absolute) and 0.040 (%). Associations between depressive symptoms and BAR were not statistically significant among former smokers or never smokers. Conclusion: Depressive symptoms were inversely associated with BAR among police officers who were current smokers and together may be considered a risk factor for cardiovascular disease among police officers. Further prospective research is warranted.