Water Treatment Characteristics of Ceramic Membrane for Aqueous Organic Matter

학위논문 (석사)-- 서울대학교 대학원 : 생태조경·지역시스템공학부 지역시스템공학전공, 2016. 2. 김성배.최근 양질의 수자원의 안정적인 공급에 대한 요구가 확대되면서 공정이 간단하고 양질의 수자원을 확보할 수 있는 막 공정이 주목을 받고 있다. 그 중에서도 세라믹 막은 물리화학적 강도와 투과성이 우수하여 다양한 분야에의 적용이 기대되고 있다. 한편, 막 공정에서 필연적으로 발생하는 막 오염은 막 공정의 효율을 떨어뜨리고 막의 수명을 단축시키게 되므로 제어할 필요가 있으며, 수처리 공정에 있어서 막 오염을 유발하는 주요한 물질은 수중에 존재하는 유기물이다. 또한, 막 오염은 막 공정의 운전인자인 막간압력차에 큰 영향을 받는 것으로 알려져 있다. 본 연구에서는 세라믹 막을 이용하여 수중에 존재하는 유기물을 제거하는 경우의 여과 특성과 막 오염 기작 및 특성을 살펴보았다. 실험은 십자류 여과방식을 이용하여 일정한 십자류유량과 온도 조건에서 막간압력차를 변화시켜 여과수가 2 L가 될 때까지 진행하였다. 유입수는 증류수 (D.W.), 모사수인 Humic acid 용액 (HA10, HA20)과 현장수 (HR, SN)를 대상으로 하였다. 유입수, 여과수, 농축수에 대하여 정성분석인 F-EEM, 정량분석인 DOC, UVA254, SUVA를 통하여 수질분석을 수행하였다. 여과실험에 앞서 세라믹 막의 성능을 평가하기 위하여 증류수를 이용하여 투과실험을 진행하였다. 실험에 사용한 세라믹 막의 투과성능 (Permeability)은 10, 25, 40 ℃로 온도가 증가함에 따라 각각 233.76 ± 2.92, 320.06 ± 5.07, 396.68 ± 4.50 LMH로 증가하였으며, 이는 온도가 올라감에 따라 물의 점성이 낮아져 flux가 증가하였기 때문이다. 유입수를 대상으로 여과실험을 수행한 결과, 막간압력차가 증가할수록 flux의 감소가 크게 일어나고 여과시간은 단축되는 경향을 보였으며, 모사수보다 현장수의 flux 감소가 크게 나타났다. 유입수, 여과수, 농축수의 수질 특성을 분석한 결과, 모사수인 HA10과 HA20은 소수성 고분자 물질로, 현장수인 HR과 SN은 친수성 저분자 물질로 주로 이루어진 것으로 나타났다. 이러한 유입수의 특성으로 인하여 여과과정에서 소수성을 가지는 모사수는 농축이 일어나면서 막 오염이 적게 발생하였으나, 친수성을 가지는 현장수는 농축이 되기보다는 막 표면에 막 오염을 유발하는 것으로 나타났다. 여과실험의 결과를 바탕으로 Hermia 모델을 이용하여 막 오염의 기작을 해석한 결과, 전체적으로 Cake formation 모델이 실험값을 가장 잘 모사하는 것으로 나타났다. 여과실험 후 단계적인 세척으로 회복된 flux와 직렬저항모델을 이용하여 막 오염 특성을 평가하였다. 막간압력차가 증가할수록 총 막 오염은 증가하였으며, 물리적 세척으로 회복이 불가능한 비가역적 막 오염의 비율 또한 증가하는 것으로 확인하였다. 또한, 모사수인 HA10과 HA20보다 현장수인 HR과 SN의 막 오염이 크게 발생하였다.제 1 장 서론 1 1.1 연구의 배경 1 1.1.1 막 공정 1 1.1.2 분리막 – 세라믹 막 2 1.1.3 막 오염 5 1.1.4 수중유기물 7 1.2 연구의 목적 8 1.3 연구의 방법 8 제 2 장 선행 문헌 연구 9 2.1 운전조건과 유입수의 특성에 따른 막 오염의 영향 9 2.2 수중 유기물 처리에 대한 세라믹 막의 적용 15 제 3 장 재료 및 방법 21 3.1 유입수 21 3.2 세라믹 막 및 세라믹 막 장치 23 3.3 실험방법 및 실험조건 27 3.3.1 실험방법 27 3.3.2 실험조건 28 3.4 수질 분석 30 3.4.1 정성 분석 30 3.4.2 정량 분석 33 3.5 모델 분석 34 3.5.1 Hermia 모델 34 3.5.2 직렬저항 모델 36 제 4 장 결과 및 고찰 38 4.1 세라믹 막의 투과 특성 38 4.1.1 Flux에 영향을 미치는 요인 38 4.1.2 Permeability 및 막 자체의 저항 41 4.2 세라믹 막의 수처리 특성 43 4.2.1 여과 특성 43 4.2.2 수질 특성 46 4.2.2.1 정성 분석 46 4.2.2.2 정량 분석 50 4.2.3 모델 분석 55 4.2.3.1 Hermia 모델 : 기작 분석 55 4.2.3.2 직렬저항 모델 : 막 오염 분석 59 제 5 장 결론 62 참고문헌 64 Abstract 73Maste

Spatial Autocorrelation of Disease Prevalence in South Korea Using 2012 Community Health Survey Data

As a basic research to investigate geographical variations of diseases, this study analyzes and compares spatial patterns of 24 different diseases in South Korea using prevalence rate data provided by Community Health Survey in 2012. Descriptive statistical analysis, global Moran"s I computation, and disease mapping were conducted to examine spatial associations and patterns of each disease. After the unique spatial patterns and distinctive spatial associations of each disease were observed, we concluded that 12 diseases displayed statistically significant spatial autocorrelation while the other 12 showed no spatial associations. This study suggests that diseases are caused by different risk factors and possess different etiological mechanisms. Furthermore, the study may lay foundation for future studies of geographical variations of disease prevalence in South Korea.ope

Changes in the Practice of Coronary Revascularization between 2006 and 2010 in the Republic of Korea

PURPOSE: Evidence suggests that technological innovations and reimbursement schemes of the National Health Insurance Service may have impacted the management of coronary artery disease. Thus, we investigated changes in the practice patterns of coronary revascularization. MATERIALS AND METHODS: Revascularization and in-hospital mortality among Koreans ≥20 years old were identified from medical claims filed between 2006 and 2010. The age- and sex-standardized procedure rate per 100,000 person-years was calculated directly from the distribution of the 2008 Korean population. RESULTS: The coronary revascularization rate increased from 116.1 (95% confidence interval, 114.9-117.2) in 2006 to 131.0 (129.9-132.1) in 2010. Compared to the rate ratios in 2006, the rate ratios for percutaneous coronary intervention (PCI) and coronary artery bypass graft (CABG) surgery in 2010 were 1.16 (1.15-1.17) and 0.80 (0.76-0.84), respectively. Among patients who received PCI, the percentage with drug-eluting stents increased from 89.1% in 2006 to 93.0% in 2010. In-hospital mortality rates from PCI significantly increased during the study period (p=0.03), whereas those from CABG significantly decreased (p=0.01). The in-hospital mortality rates for PCI and CABG were higher in elderly and female patients and at the lowest-volume hospitals. CONCLUSION: The annual volume of coronary revascularization continuously increased between 2006 and 2010 in Korea, although this trend differed according to procedure type. A high percentage of drug-eluting stent procedures and a high rate of in-hospital mortality at low-volume hospitals were noted.ope

Suicide loss, changes in medical care utilization, and hospitalization for cardiovascular disease and diabetes mellitus

AIMS: The impact of suicide loss on family members' cardiometabolic health has little been evaluated in middle-aged and elderly people. We investigated the effect of suicide loss on risks for cardiovascular disease (CVD) and diabetes mellitus (DM) in suicide completers' family members using a national representative comparison group. METHODS AND RESULTS: The study subjects were 4253 family members of suicide completers and 9467 non-bereaved family members of individuals who were age and gender matched with the suicide completers in the Republic of Korea. National health insurance data were used to identify medical care utilization during the year before and after a suicide loss. A recurrent-events survival analysis was performed to estimate the hazard ratios (HRs) of hospitalizations for CVD, DM, or psychiatric disorders, after adjusting for age, residence, and socioeconomic status. Among subjects without a past history of CVD, DM, or psychiatric disorders, the increased risks of recurrent hospitalizations were observed for CVD [HR 1.343, 95% confidence interval (CI) 1.001-1.800 in men; HR 1.240, 95% CI 1.025-1.500 in women] and DM (HR 2.238, 95% CI 1.379-3.362 in men; HR 1.786, 95% CI 1.263-2.527 in women). In subjects with a past history of CVD, DM, or psychiatric disorders, the number of medical care visits decreased after a suicide loss, and suicide completers' family members showed lower rates of hospitalization for CVD and DM than the comparison group. CONCLUSION: Compared with non-bereaved family members, suicide completers' family members without a past history of CVD, DM, or psychiatric disorder showed a high risk of hospitalization for those conditions.ope

Residential radon and environmental burden of disease among Non-smokers

BACKGROUND: Lung cancer was the second highest absolute cancer incidence globally and the first cause of cancer mortality in 2014. Indoor radon is the second leading risk factor of lung cancer after cigarette smoking among ever smokers and the first among non-smokers. Environmental burden of disease (EBD) attributable to residential radon among non-smokers is critical for identifying threats to population health and planning health policy. METHODS: To identify and retrieve literatures describing environmental burden of lung cancer attributable to residential radon, we searched databases including Ovid-MEDLINE, -EMBASE from 1980 to 2016. Search terms included patient keywords using 'lung', 'neoplasm', exposure keywords using 'residential', 'radon', and outcomes keywords using 'years of life lost', 'years of life lost due to disability', 'burden'. Searching through literatures identified 261 documents; further 9 documents were identified using manual searching. Two researchers independently assessed 271 abstracts eligible for inclusion at the abstract level. Full text reviews were conducted for selected publications after the first assessment. Ten studies were included in the final evaluation. REVIEW: Global disability-adjusted life years (DALYs)(95 % uncertainty interval) for lung cancer were increased by 35.9 % from 23,850,000(18,835,000-29,845,000) in 1900 to 32,405,000(24,400,000-38,334,000) in 2000. DALYs attributable to residential radon were 2,114,000(273,000-4,660,000) DALYs in 2010. Lung cancer caused 34,732,900(33,042,600 ~ 36,328,100) DALYs in 2013. DALYs attributable to residential radon were 1,979,000(1,331,000-2,768,000) DALYs for in 2013. The number of attributable lung cancer cases was 70-900 and EBD for radon was 1,000-14,000 DALYs in Netherland. The years of life lost were 0.066 years among never-smokers and 0.198 years among ever-smoker population in Canada. CONCLUSION: In summary, estimated global EBD attributable to residential radon was 1,979,000 DALYs for both sexes in 2013. In Netherlands, EBD for radon was 1,000-14,000 DALYs. Smoking population lost three times more years than never-smokers in Canada. There was no study estimating EBD of residential radon among never smokers in Korea and Asian country. In addition, there were a few studies reflecting the age of building, though residential radon exposure level depends on the age of building. Further EBD study reflecting Korean disability weight and the age of building is required to estimate EBD precisely.ope

Elevation of Serum Aminotransferase Levels and Future Risk of Death from External Causes: A Prospective Cohort Study in Korea

PURPOSE: The association between liver enzymes and death from external causes has not been examined. We investigated the association between serum aminotransferase levels and external-cause mortality in a large prospective cohort study. MATERIALS AND METHODS: A total of 142322 subjects of 35-59 years of age who completed baseline examinations in 1990 and 1992 were enrolled. Mortalities were identified using death certificates. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were categorized into quintiles. Sub-distribution hazards ratios and 95% confidence intervals (CIs) were estimated using a competing risks regression model in which deaths from other causes were treated as competing risks. RESULTS: Of 8808 deaths, 1111 (12.6%) were due to external causes. Injury accounted for 256 deaths, and suicide accounted for 255. After adjusting for covariates, elevated ALT and AST were significantly associated with an increased risk of all external-cause mortalities, as well as suicide and injury. Sub-distribution hazards ratios (95% CIs) of the highest versus the lowest quintiles of serum ALT and AST were, respectively, 1.57 (1.26-1.95) and 1.45 (1.20-1.76) for all external causes, 2.73 (1.68-4.46) and 1.75 (1.15-2.66) for suicide, and 1.79 (1.10-2.90) and 1.85 (1.21-2.82) for injury. The risk of external-cause mortality was also significantly higher in the fourth quintile of ALT (21.6-27.5 IU/L) than in its first quintile. CONCLUSION: Elevated aminotransferase levels, even within the normal range, were significantly associated with increased risk of all external-cause mortalities, including suicide, and injury.ope

Short-term Effects of Ambient Air Pollution on Emergency Department Visits for Asthma: An Assessment of Effect Modification by Prior Allergic Disease History

Objectives : The goal of this study was to investigate the short-term effect of ambient air pollution on emergency department (ED) visits in Seoul for asthma according to patients’ prior history of allergic diseases. Methods : Data on ED visits from 2005 to 2009 were obtained from the Health Insurance Review and Assessment Service. To evaluate the risk of ED visits for asthma related to ambient air pollutants (carbon monoxide [CO], nitrogen dioxide [NO2], ozone [O3], sulfur dioxide [SO2], and particulate matter with an aerodynamic diameter <10 μm [PM10]), a generalized additive model with a Poisson distribution was used; a single-lag model and a cumulative-effect model (average concentration over the previous 1-7 days) were also explored. The percent increase and 95% confidence interval (CI) were calculated for each interquartile range (IQR) increment in the concentration of each air pollutant. Subgroup analyses were done by age, gender, the presence of allergic disease, and season. Results : A total of 33 751 asthma attack cases were observed during the study period. The strongest association was a 9.6% increase (95% CI, 6.9% to 12.3%) in the risk of ED visits for asthma per IQR increase in O3 concentration. IQR changes in NO2 and PM10 concentrations were also significantly associated with ED visits in the cumulative lag 7 model. Among patients with a prior history of allergic rhinitis or atopic dermatitis, the risk of ED visits for asthma per IQR increase in PM10 concentration was higher (3.9%; 95% CI, 1.2% to 6.7%) than in patients with no such history. Conclusions : Ambient air pollutants were positively associated with ED visits for asthma, especially among subjects with a prior history of allergic rhinitis or atopic dermatitis.ope

A Case of Kommerell's Diverticulum Initially Detected by Transesophageal Echocardiography

Kommerell's diverticulum is a rare congenital disorder characterized by typical right sided aortic arch and aberrant left subclavian artery which are usually detected by accident in asymptomatic patients. However, some of patients complain of severe symptoms caused by compression of the adjacent organs or complicated aortic dissection by the diverticulum. Early detection of the disease can lead to elective surgical correction. In this article, we report a Kommerell's diverticulum case initially detected by transesophageal echocardiography.ope

Decreased blood pressure associated with in-vehicle exposure to carbon monoxide in Korean volunteers

BACKGROUND: Carbon monoxide (CO) is one of the primary components of emissions from light-duty vehicles, and reportedly comprises 77% of all pollutants emitted in terms of concentration. Exposure to CO aggravates cardiovascular disease and causes other health disorders. The study was aimed to assess the negative effects by injecting different amounts of CO concentration directly to human volunteers boarding in the car. METHODS: Human volunteers were exposed to CO concentrations of 0, 33.2, and 72.4 ppm, respectively during the first test and 0, 30.3, and 48.8 ppm respectively during the second test while seated in the car. The volunteers were exposed to each concentration for approximately 45 min. After exposure, blood pressure measurement, blood collection (carboxyhemoglobin [COHb] analysis), medical interview, echocardiography test, and cognitive reaction test were performed. RESULT: In patients who were exposed to a mean concentration of CO for 72.4 ± 1.4 ppm during the first exposure test and 48.8 ± 3.7 ppm during the second exposure test, the COHb level exceeded 2%. Moreover, the diastolic blood pressure was decreased while increasing in CO concentration after exposure. The medical interview findings showed that the degree of fatigue was increased and the degree of concentration was reduced when the exposed concentration of CO was increased. CONCLUSION: Although the study had a limited sample size, we found that even a low concentration of CO flowing into a car could have a negative influence on human health, such as change of blood pressure and degree of fatigue.ope

Medical Care Utilization During 1 Year Prior to Death in Suicides Motivated by Physical Illnesses

OBJECTIVES: Many epidemiological studies have suggested that a variety of medical illnesses are associated with suicide. Investigating the time-varying pattern of medical care utilization prior to death in suicides motivated by physical illnesses would be helpful for developing suicide prevention programs for patients with physical illnesses. METHODS: Suicides motivated by physical illnesses were identified by the investigator's note from the National Police Agency, which was linked to the data from the Health Insurance Review and Assessment. We investigated the time-varying patterns of medical care utilization during 1 year prior to suicide using repeated-measures data analysis after adjustment for age, gender, area of residence, and socioeconomic status. RESULTS: Among 1994 suicides for physical illness, 1893 (94.9%) suicides contacted any medical care services and 445 (22.3%) suicides contacted mental health care during 1 year prior to suicide. The number of medical care visits and individual medical expenditures increased as the date of suicide approached (p<0.001). The number of medical care visits for psychiatric disorders prior to suicide significantly increased only in 40- to 64-year-old men (p=0.002), women <40 years old (p=0.011) and women 40 to 64 years old (p=0.021) after adjustment for residence, socioeconomic status, and morbidity. CONCLUSIONS: Most of the suicides motivated by physical illnesses contacted medical care during 1 year prior to suicide, but many of them did not undergo psychiatric evaluation. This underscores the need for programs to provide psychosocial support to patients with physical illnesses.ope