Factors associated with the non-screening status of cervical cancer screening test in Korean adult women : Korea National Health and Nutrition Examination Survey (2010–2012)

Background: This study aimed to explore the associations of social-demographic, health-behavioral, and woman-specific factors with the non-screening status of the cervical cancer screening test in Korean adult women. Methods: This study was a cross-sectional analysis of 9,698 Korean adult women aged 20 years or more who participated in the Korea National Health and Nutrition Examination Surveys V (2010?2012). Rao-Scott chi-square tests and survey logistic regression analyses were employed respectively to analyze the difference in the non-screening status of the cervical cancer screening test by each characteristic and to explore the factors related to the non-screening status. Results: The rate of the non-screening status of the cervical cancer screening test was 53.5% over the previous 2 years. In the survey logistics regression analysis, age, marital status, educational levels, income levels, residential area, occupation, private health insurance, smoking, alcohol, obesity, menstrual status, pregnancy experience, and hormone replacement therapy were significantly associated with the non-screening status of the cervical cancer screening test. Conclusion: On the basis of the results of this study, some social-demographic, health-behavioral, and woman-specific characteristics of Korean adult women seem to affect the non-screening status of the cervical cancer screening test. Therefore, appropriate health policies need to be designed, implemented, monitored, and evaluated to reduce the non-screening status of the cervical cancer screening test of them.ope

평균장 균질화법 및 다중스케일 유한요소 모델을 활용한 알루미늄 주조합금의 기계적 물성 및 파괴거동 예측

학위논문(박사) -- 서울대학교대학원 : 공과대학 재료공학부, 2021.8. 이명규.Cast Al alloys are commonly used in the aerospace and automobile industries because of their excellent properties such as weldability, corrosion resistance, wear-resistance, and lightweight. Herein, Si, Mg, and Mn were added to the A365.0-T6 alloy, and the resulting material was characterized. Si was added to increase castability, and magnesium and manganese are the main added elements. The microstructure and mechanical properties of the material are determined via the T6 heat treatment process, which undergoes artificial aging after the solution heat treatment. Cast Al alloys comprise the Al matrix, silicon particles, intermetallic compounds, and Mg2Si precipitates. Besides, void defects are observed because of the entrained air during casting. Cast Al alloys exhibit a large spread of fracture strain because of the large pores in the material. In the absence of pores, voids are formed due to the cracking of Si particles, which are inclusions, and the strain is concentrated between the cracked Si particles, causing material damage. In addition, in ductile metallic materials, failure is explained by the nucleation, growth, and coalescence of voids; thus, microvoids also affect the material’s mechanical properties. Therefore, the Al matrix, Si particles, and voids among the microstructure of the cast Al alloy are the main factors affecting the mechanical and fracture behavior of the material. Herein, the mechanical behavior and fracture scatter of cast Al alloys were described by multiscale modeling based on the material properties of microstructures. Performing the finite element analysis by dispersing the microstructures, similar to the distribution of real substances, was inefficient; therefore, the Mori–Tanaka (MT) mean-field method was introduced as an alternate. The MT mean-field approach can derive the homogenized mechanical behavior of a material comprising two phases based on several assumptions and Eshelby’s equation. Compared with calculating the average behavior of multiple phases using the representative volume element, the calculation is more efficient and can easily apply microstructures of various distributions. Assuming that the microvoids belong to the Al matrix, the cast Al alloy can be considered as a material comprising two phases of an Al matrix and Si particles, so that MT can be applied. The stress and strain of the Al matrix and Si particles were also calculated while calculating the homogenized mechanical response using MT. Because the Al matrix was assumed to contain microvoids, the mechanical behavior was computed by applying the Gurson–Tvergaard–Needleman (GTN) model, which is a damage-coupled model that describes the damage caused by the growth and coalescence of voids. Because the Si particles deform only elastically, the stress was calculated using the generalized Hooke’s law. The Weibull distribution function was used to determine whether the Si particles were cracked, and the nucleated voids by the cracks in the Si particles were added to the Al matrix and modeled to be applied while calculating the material damage using the GTN model. Tensile tests were performed using different shapes of specimens to measure the mechanical and fracture behavior of the cast Al alloys under different stress triaxialities. The material’s microstructure before deformation was observed to obtain the microstructural distribution information of the material required for the microstructure-based model. The distribution of microstructures was statistically analyzed using X-ray tomography, optical microscopy, and scanning electron microscopy, and based on these analyses, it was applied to computational simulations according to probability. The feasibility of the method proposed in this paper was verified by observing the microstructural changes after deformation. The results predicted using the proposed microstructure-based model were in good agreement with the experimental results of the mechanical and fracture behavior of cast Al alloys. The effect of the distribution and size of voids on the material’s fracture was analyzed. In particular, we confirmed that the macrovoids considerably affect the fracture of the material. The proposed model can explain the material’s damage evolution process starting from the cracking of the Si particles and the specimen fractures off-center.알루미늄 주조 합금은 용접성, 부식 저항성 마모 저항성 등의 특성이 우수하고, 가벼워서 항공우주분야 및 자동차 산업에서 널리 사용된다. 본 논문에서 다루는 알루미늄 주조 합금은 A365.0-T6로 주조성을 높이기 위하여 규소(Si)를 첨가한 것이 특징이며, 마그네슘 및 망간이 주요 첨가 원소이다. 용체화 처리 후 인공 시효를 거치는 T6 열처리과정을 통하여 재료의 미세조직과 기계적 물성이 정해진다. 알루미늄 주조 합금은 알루미늄 기지(Matrix)와 규소 입자(Si particle), 금속간 화합물, Mg2Si 석출물로 구성되어 있으며, 주조 공정 중 혼입된 공기로 인한 기공(Void) 결함이 관찰된다. 알루미늄 주조 합금은 큰 산포의 파단 변형률을 갖는다. 이는 재료 내에 존재하는 커다란 기공에 의한 것으로 알려져 있다. 기공이 없는 경우에는 개재물인 규소 입자의 균열로 인해 기공이 형성되고, 균열된 규소 입자 사이에 변형이 집중되어 재료의 손상을 유발하는 것으로 알려져 있다. 또한 일반적으로 연성 금속재료의 경우 기공의 형성, 성장, 합체로 파단을 설명하곤 하므로, 미소 기공도 재료의 기계적 물성에 영향을 미친다고 할 수 있다. 그러므로, 알루미늄 주조 합금의 미세조직 중 알루미늄 기지, 규소 입자, 기공이 재료의 기계적 거동과 파단 거동에 영향을 주는 주요 요소라 할 수 있다. 본 연구에서는 이러한 미세조직들의 물성에 기반한 멀티스케일 모델링을 통하여 알루미늄 주조 합금의 기계적 거동 및 산포를 보이는 파단 거동을 모사하고자 하였다. 미세조직의 분포를 실제 재료와 똑같이 유한요소 해석 상에서 구현하는 것은 효율적이지 않으므로, 이를 대체할 방법으로 모리-다나카 평균장 이론(Mori-Tanaka mean–field method, MT)을 도입했다. MT는 두 상(phase)으로 구성된 재료의 균질화된 기계적 거동을 몇 가지 가정과 Eshelby의 식을 바탕으로 도출할 수 있는 방법이다. RVE를 활용하여 다 상의 평균 거동을 계산하는 방법에 비하여 계산의 효율이 좋고, 다양한 분포의 미세조직을 보다 용이하게 적용할 수 있는 장점이 있다. 미소기공이 알루미늄 기지에 속한다 가정하면, 알루미늄 주조합금은 알루미늄 기지와 규소 입자 두 상으로 이루어진 재료로 간주할 수 있으므로 MT의 적용이 가능해진다. MT로 균질화된 기계적 반응을 계산하는 과정에서 알루미늄 기지와 규소 입자의 응력 및 변형율도 함께 산출된다. 알루미늄 기지는 기공을 포함한다고 가정하였으므로, 기공의 성장 및 결합 (Coalescence)으로 인한 손상을 모사하는 damage coupling 모델인 Gurson-Tvergaard-Needleman (GTN) 모델을 적용하여 기계적 거동을 나타냈다. 규소 입자는 탄성 변형만 하므로 일반화된 훅의 법칙으로 응력을 산출했다. 바이불 분포 함수(Weibull distribution function)를 활용하여 규소 입자의 균열 여부를 판단했다. 규소 입자의 균열로 인해 생성되는 기공은 알루미늄 기지에 추가하여 GTN 모델로 재료의 손상을 계산할 때 적용되도록 모델링했다. 알루미늄 주조 합금이 다양한 응력 상태 아래에서 보이는 기계적 거동 및 파단 거동을 측정하기 위해 여러 형상의 시편을 활용하여 인장 실험을 진행했다. 미세조직 기반의 모델에 필요한 재료의 미세조직 분포 정보 획득을 위해 재료의 변형 전 미세조직을 관찰했다. Micro–CT, 광학현미경, 주사전자 현미경을 활용하여 미세조직을 통계적으로 분석했고, 이를 바탕으로 전산모사에 확률에 기반하여 적용했다. 변형 후의 미세조직 변화도 관찰하여 이 논문에서 제안한 방법의 타당성을 검증했다. 제안한 미세조직 기반 파단 예측 모델이 알루미늄 주조 합금의 기계적 거동 및 파단 거동을 잘 모사하는 것을 확인했으며, 기공의 분포와 크기가 재료의 파단에 미치는 영향을 분석했다. 특히 거대한 기공이 재료의 파단에 큰 영향을 주는 것을 확인했다. 규소 입자의 균열로부터 시작되는 재료의 손상 진화 과정, 삼축 응력도가 클수록 파단에 빨리 이르는 현상, 시편의 파단이 중앙이 아닌 곳에서 나타나는 현상을 제안된 모델로 모사할 수 있었다.1. Introduction 1 1.1. Cast Al alloy 1 1.2. Mechanical properties of cast Al alloy 3 1.3. Fracture approaches of cast Al alloy 4 1.4. Homogenization method of multiphase materials 5 1.5. Research objectives 7 2. Microstructure-based fracture model 8 2.1. MoriTanaka mean-field method 8 2.1.1. Mean-field homogenization 9 2.1.2. Homogenization method 11 2.1.3. MoriTanaka mean-field method 12 2.1.4. Implementation of MoriTanaka mean-field method 14 2.2. Modified GursonTvergaardNeedleman model 17 2.2.1. GursonTvergaardNeedleman model 17 2.2.2. Shear-modified GTN model 20 2.2.3. Implementation of shear-modified GTN model 24 2.2.4. Calculation of consistent tangent modulus 29 2.3. Weibull distribution function 32 2.4. Summary of algorithmic implementation 33 3. Experiments 39 3.1. Mechanical test 39 3.2. Statistical microstructural analysis 44 3.3. Microstructural analysis using Energy-dispersive spectroscopy (EDS) 48 4. Finite element simulation 52 4.1. Simulation conditions 52 4.2. Parameter identification 56 4.3. Model validation 65 5. Discussion 68 5.1. Mechanism of void nucleation 68 5.2. Effect of macroscopic voids on ductile fracture 60 5.3. Detailed analysis of fracture evolution 73 5.4. Effect of macrovoid on ductile fracture 85 5.5. Fracture behavior with few voids 93 6. Conclusion 95박

Relationship between Physical Function Factors and Discrimination Experiences of the Elderly in Korea: The 2014 and 2017 National Survey on Living Conditions and Welfare Needs of Korean Older Persons

Background: Supporting the elderly population is presented as a social issue, and it affects age discrimination, which forms a negative perception and avoids the elderly. Since age discrimination lowers the quality of life of the elderly and hinders social unity, it may be important to research related factors. This study examined the physical function as a factor that influences discrimination experiences and aimed to identify the relationship between physical function factors and discrimination experiences. Methods: In this study, we analyzed 20,225 elderly from the 2014 and 2017 survey of living conditions and welfare needs of Korean older persons, conducted nationwide among older than 65 years. Physical function factors are activities of daily living, instrumental activities of daily living, sight discomfort, hearing discomfort, chewing discomfort, and leg strength as factors of interest. We performed multivariable logistic regression that reflected survey characteristics, adjusting for socio-demographic factors, health related factors, and social-support factors. Results: The number of elderly who faced discrimination experiences was 1,175 (5.8%). The results showed that the odds ratio of facing a discrimination experience in the dependent group was significantly higher compared to the independent group when being transferring out of the room (4.05; 95% confidence interval [CI], 1.50–10.88) and difficulty in hearing (1.25; 95% CI, 1.05–1.49). Even with respect to chewing ability, which was significant in models 1 and 2, they face more discrimination experiences (1.30; 95% CI, 1.11–1.53). Conclusion: These research results indicate that an important strategy for preventing age discrimination is to understand the physical function conditions of the elderly and promote the physical functions of the elderly related to transferring, hearing, and chewing; it is necessary to develop a practical intervention plan that considers these aspects.ope

Factors Associated with Self-Rated Health among Poor Glycemic Control Group with Diabetes Mellitus: The 4th-6th Korea National Health and Nutrition Examination Survey (2007-2015)

Background: This study aimed to properly manage diseases such as blood sugar control so that patients with diabetes can benefit from both medication and health activities. Also, these health practices are greatly influenced by self-rated health, a subjective assessment of health status. Because self-rated health does not necessarily match the objective health status, it is important to identify which factors affect self-rated health. Methods: For the study, the data was gathered from the 4th–6th National Health Nutrition Survey (2007–2015). Out of the total 73,353 participants in the survey, 2,303 patients with uncontrolled blood sugar with an HbA1c level of more than 7% were selected for the final study. Dependent variables fell into two categories depending on how the participant reported whether he or she was in good health or not. Independent variables included socio-demographics, health behavioral, and health status factors. This study performed logistic regression analysis. Results: Out of 2,303 participants, 18.1% reported that their heath was ‘good,’ despite the fact that their blood sugar level was not controlled. After running a logistic regression model, the odds ratio of groups that perceive subjective health awareness as good was higher in the groups of people as below: in the people over 60 years old; in the people who graduated from a junior college or higher than those who had a level of education of primary school completion or less; in the people living in Chungnam than those living in Seoul; and in the group with hypertriglyceridemia. Conclusion: The study identified factors associated with those failed to perceive the blood sugar level as a severe health problem despite of the fact that blood sugar was not controlled. To improve public health, diabetes management policies need to be addressed to population groups with these problems above.ope

Association between arthritis and socio-demographic factors in Korean elderlies : the National Survey of Korean Elderly (2014, 2017) dataset analysis

Background: As South Korea is becoming an aged society very rapidly, the increase in osteoarthritis prevalence raises various public health issues in this country. This study aimed to explore the socio-demographic factors associated with osteoarthritis in the current Korean elderlies. Methods: Using the National Survey of Korean Elderly data (2014, 2017), we analyzed 20,326 elderlies (males, 8,248; females, 12,078) and conducted multivariate logistic regression analyses by sex. The dependent variable is whether a participant was diagnosed with osteoarthritis or not. Independent variables of interest is socio-demographic factors such as age, marital status, household type, residential area, household income, religion, the longest job, the number of close relatives, the number of close friends, and survey year. Control variables are various health behavioral factors and disease-related factors. Results: Prevalence of osteoarthritis was 19.2% in male elderlies and 47.0% in female elderlies. According to the results of the multivariate logistic regression adjusted for all studied control variables, the odds ratio (OR) for having osteoarthritis of under-elementary school graduates (their counterpart was college graduate group) was 1.81 (95% confidence interval [CI], 1.29– 2.52) in males and 1.67 (95% CI, 1.12–2.47) in females. The OR of those having a job in agriculture & forestry fishery as their longest job (their counterpart was those who had never participated in labor force during their lifetime) was 5.07 (95% CI, 1.46–17.58) in males and 1.49 (95% CI, 1.27–1.74) in females. In males, the second-low quartile group in household yearly income (their counterpart was the highest quartile group) had the OR of 1.22 (95% CI, 0.98–1.53). In females, the OR of those having a religion of Buddhism (their counterpart was those having no religion) was 1.20 (95% CI, 1.07–1.35) and the OR of those who had no relatives (their counterpart was those having more than 3 close relatives) was 1.31 (95% CI, 1.10–1.56). Conclusion: This study found that in Korean elderlies, education, the longest job, household income, religion, and the number of close relatives are associated with their suffering from osteoarthritis. Further study and designing appropriate interventions are needed to alleviate current and future individual and socioeconomic burdens of osteoarthritis in an aged society like South Korea.ope

Socioeconomic costs of liver disease in Korea

BACKGROUND/AIMS: This study analyzed the scale and trends of the social and economic costs of liver disease in Korea for the past 5 years. METHODS: The social aspects of socioeconomic costs were projected for viral hepatitis (B15-B19), liver cirrhosis, malignant neoplasm of the liver (C22) and other liver diseases (K70-K76), as representative diseases by dividing costs into direct and indirect from 2004 to 2008. Direct costs include hospitalization, outpatient, and pharmacy costs in the health-care sector, and transportation and caregiver costs. Indirect costs include the future income loss due to premature death and the loss of productivity resulting from absence from work. RESULTS: The social and economic costs of liver disease were projected to be KRW 5,858 billion in 2004, KRW 5,572 billion in 2005, KRW 8,104 billion in 2006, KRW 6,095 billion in 2007, and KRW 5,689 billion in 2008. The future income loss resulting from premature death is thus greatest, from 73.9% to 86.1%, followed by the direct medical costs, from 9.0% to 18.1%. The productivity loss resulting from absence from work accounts for 3.3-5.5%, followed by the direct nonmedical costs such as transportation and caregiver costs, at 1.5-2.5%. CONCLUSIONS: Among the socioeconomic costs of liver disease in Korea, the future income loss resulting from premature death is showing a decreasing trend, whereas direct medical costs are increasing dramatically.ope

Factors Associated with Poor Glycemic Control among Patients with Type 2 Diabetes Mellitus: The Fifth Korea National Health and Nutrition Examination Survey (2010-2012)

Background: Glycemic control is an effective way to reduce the cardiovascular complications of diabetes, but more than half of the adults with diabetes in Korea are improperly controlling their glycemic levels. The purpose of this study is to identify the factors associated with poor glycemic control in type 2 diabetes patients. Methods: This study analyzed 1,261 subjects ≥30years≥30years old diagnosed with type 2 diabetes who participated in the fifth Korean National Health and Nutrition Examination Survey (2010-2012). Poor glycemic control rates were defined as hemoglobin A1c (HbA1c) level ≥7≥7 . To shed light on the causes of poor glycemic control, socio-demographics, diabetes severity, health status, and health behavior factors were adjusted and logistic regression was done. Results: Of the total 1,261 patients, 53.0% of patients with type 2 diabetes had HbA1c ≥7≥7 . After running a logistic regression model, the odds ratio of poor glycemic control was higher in high school graduates than elementary school graduates; in people living in Chungcheong and Jeolla/Jeju than those living in Seoul; in the group with diabetes for over 5 years had diabetes less than 5 years; in a group with insulin and oral hypoglycemic agent treatment than non-treatment; in a group with hypertriglyceridemia than without hypertriglyceridemia; and in the group with slept less than 6 hours slept 7-8 hours. Conclusion: We need a comprehensive public health policy to reduce the poor glycemic control rates in type 2 diabetes patients. We should recognize the education levels, duration of diabetes, diabetes treatment, hypertriglyceridemia, and sleep duration were associated with poor glycemic control.ope

Which Occupation is Highly Associated with Cognitive Impairment? A Gender-Specific Longitudinal Study of Paid and Unpaid Occupations in South Korea

Background: To examine the associations between paid and unpaid occupations and the risk of cognitive impairment with respect to gender in a middle-aged population using the dataset of a nationally representative longitudinal survey. Methods: Overall, 24,925 observations of 5865 participants aged 45-64 years were sampled from the seven waves of the Korean Longitudinal Study of Ageing (2006-2018). A dichotomous outcome variable was derived based on the Korean version of the Mini-Mental State Examination scores, and occupations were grouped into 12 categories, including three unpaid ones. Sociodemographics, lifestyle, and medical conditions were included as covariates in the mixed logistic regression models. Adjusted odds ratios and predicted probabilities of cognitive impairment were estimated. Results: In the longitudinal models with all-studied covariates, the risk of cognitive impairment was similar between genders but differed across occupation categories for each gender. Moreover, the association between occupation and cognitive impairment varied between genders. Regarding the predicted probability, in men, the retired category exhibited the highest risk of cognitive impairment. However, in women, the highest risk was related to the homemakers category, with the risk being more than five times higher than those in the professionals and related workers category. Conclusions: Public health policies to reduce the risk of cognitive impairment in the middle-aged population need to be designed and implemented with respect to both gender and occupation.ope

A Reversal of the Association between Education Level and Obesity Risk during Ageing: A Gender-Specific Longitudinal Study in South Korea

This study aimed to examine and quantify obesity risk across different education levels during ageing using the dataset of a nationally representative longitudinal survey. A total of 45,391 observations of 9991 individuals aged ≥45 years were included in this study. Obesity was defined as a body mass index of ≥25, according to a guideline for Asians by the World Health Organization, and education level was grouped into three categories. Socio-demographics, lifestyles, and health conditions were used as covariates. Adjusted odds ratios and predicted probabilities of obesity were computed and adjusted for a complex survey design. With respect to gender, education level and age were significantly associated with obesity risk, and the association was stronger in women than in men. Furthermore, education level was negatively associated with obesity risk in the middle age in each gender. However, the association became positive in the old age, specifically among highly educated women. Therefore, policy efforts to reduce obesity risk and the resulting education gradients should be established based on studies considering their old age. Further longitudinal studies are required to examine whether these findings are valid in other socio-cultural or economic settings.ope

Differential Risk of Cognitive Impairment across Paid and Unpaid Occupations in the Middle-Age Population: Evidence from the Korean Longitudinal Study of Aging, 2006-2016

To examine and quantify the risk of cognitive impairment across a variety of occupations including unpaid work in a middle-age population using the dataset of a nationally representative longitudinal survey. A total of 20,932 observations of 5865 subjects aged 45-64 were obtained from six waves of the Korean Longitudinal Study of Aging (2006-2016). A dichotomous outcome variable was constructed on the basis of the Korean Versions of the Mini-Mental State Examination scores, and occupations were grouped into 10 occupation categories, including unpaid housekeepers. Socio-demographics, lifestyle, and medical conditions were used as covariates in mixed logistic regression models. Adjusted odds ratios and predicted probabilities of cognitive impairment were computed and adjusted for a complex survey design. In longitudinal models with all studied covariates, the risk of cognitive impairment differed significantly across occupation categories, but the association of occupation with the risk of cognitive impairment was the same between genders. In terms of the predicted probability, the risk of cognitive impairment in the unpaid housekeepers' category (11.2%, 95% confidence interval (CI): 10.4% to 11.9%) was the highest among occupation categories, being three times higher than in the professionals' and related workers' category (3.7%, 95% CI: 1.6% to 5.7%). Public policies based on studies of the risk of cognitive impairment across different occupations in the middle-age population should be designed so as to prevent cognitive impairment in the middle-age population as well as their older life stages, particularly targeting high-risk groups such as people engaged in unpaid domestic and care activities.ope