• Journal of Chest Surgery
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• v.53 no.1
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• pp.1-7
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• 2020

Background: The aim of this study was to evaluate the short-term and long-term results of surgical treatment for native valve endocarditis (NVE) and to investigate the risk factors associated with mortality. Methods: Data including patients' characteristics, operative findings, postoperative results, and survival indices were retrospectively obtained from Hallym University Sacred Heart Hospital. Results: A total of 29 patients underwent surgery for NVE (affecting the mitral valve in 20 patients and the aortic valve in 9) between 2003 and 2017. During the follow-up period (median, 46.9 months; interquartile range, 19.1-107.0 months), the 5-year survival rate was 77.2%. In logistic regression analysis, body mass index (p=0.031; odds ratio [OR], 0.574; 95% confidence interval [CI], 0.346-0.951), end-stage renal disease (ESRD) (p=0.026; OR, 24.0; 95% CI, 1.459-394.8), and urgent surgery (p=0.010; OR, 34.5; 95% CI, 2.353-505.7) were significantly associated with in-hospital mortality. Based on Cox proportional hazard regression analysis, the statistically significant predictors of long-term outcomes were hypertension, ESRD, and urgent surgery. Conclusion: Surgical treatment for NVE is associated with considerable mortality. The in-hospital mortality and 5-year survival rates of this study were 13.8% and 77.2%, respectively. Underlying conditions, including hypertension and ESRD, and urgent surgery were independent risk factors for unfavorable outcomes.

• Tunnel and Underground Space
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• v.8 no.2
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• pp.107-117
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• 1998

In the case of a fire disaster in a uni-directional road tunnel, it is important to determine the critical ventilation velocity to prevent the backflow travelling toward the tunnel exit where vehicles are stopped. The critical ventilation velocity is horizontal velocity to prevent hot smoke from moving toward the tunnel exit. According to Froude modelling, the model tunnel whcih was 300mm in diameter and 21 m in length was made of acryl tubes. Inner section of acryl tubes was clothed with polycarbonate. 1/20 scaled model vehicles were installed to simulate the situation that vehicles are stopped in the tunnel exit. Methanol in a pool type burner was burned in the middle of tunnel to simulate a fire hazard. In this study, the basis of determining the critical ventilation velocity is the ventilation flow rate that is able to maintain the allowable CO concentration in the tunnel section. We assumed that the allowable CO concentration was backflow dispersion index. Futhermore, We intended to find out CO distribution and temperature distribution according as we changed ventilation velocity. The results of this study were that no backflow happened when ventilation velocity was 0.52 m/s in the case of 5.75 kW. If we adapt these results of a fire disaster releasing 10MW heat capacity in real tunnel which is 400m in length, no backflow happens when ventilation velocity is 2.31m/s. After we figured out dimensionless heat release rate and dimensionless ventilation velocity of model test and those of real test to verify experimental correctness, we tried to find out correlation between experimental results of model tunnel and those of real tunnel.

• Toxicological Research
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• v.29 no.1
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• pp.69-79
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• 2013

The purpose of this study was to investigate the current status of metal pollution in the sediment from rivers, lakes, and streams in active gold mining districts in Ghana. Two hundred and fifty surface sediment samples from 99 locations were collected and analyzed for concentrations of As, Hg, Cr, Co, Cu, Fe, Zn, Pb, Cd, Ni, and Mn using inductively coupled plasma-mass spectroscopy (ICP-MS). Metal concentrations were then used to assess the human health risks to resident children and adults in central tendency exposure (CTE) and reasonable maximum exposure (RME) scenarios. The concentrations of Pb, Cd, and As were almost twice the threshold values established by the Hong Kong Interim Sediment Quality Guidelines (ISQG). Hg, Cu, and Cr concentrations in sediment were 14, 20, and 26 times higher than the Canadian Freshwater Sediment Guidelines for these elements. Also, the concentrations of Pb, Cu, Cr, and Hg were 3, 11, 12, and 16 times more than the Australian and New Zealand Environment and Conservation Council (ANZECC) sediment guideline values. The results of the human health risk assessment indicate that for ingestion of sediment under the central tendency exposure (CTE) scenario, the cancer risks for child and adult residents from exposure to As were $4.18{\times}10^{-6}$ and $1.84{\times}10^{-7}$, respectively. This suggests that up to 4 children out of one million equally exposed children would contract cancer if exposed continuously to As over 70 years (the assumed lifetime). The hazard index for child residents following exposure to Cr(VI) in the RME scenario was 4.2. This is greater than the United States Environmental Protection Agency (USEPA) threshold of 1, indicating that adverse health effects to children from exposure to Cr(VI) are possible. This study demonstrates the urgent need to control industrial emissions and the severe heavy metal pollution in gold mining environments.

• Korean Journal of Community Nutrition
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• v.21 no.4
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• pp.354-365
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• 2016

Objectives: Studies that reported the association between diet quality/nutritional intake status and mortality have rarely used long-term follow-up data in Asian countries, including Korea. This study investigated the association between the risk of mortality (all-cause and cause-specific) and the diet quality/nutritional intake status using follow-up 12-year mortality data from a nationally representative sample of South Koreans. Methods: 8,941 individuals who participated in 1998 and 2001 Korea Health and Nutrition Examination Surveys were linked to mortality data from death certificates. Of those individuals, 1,083 (12.1%) had died as of December, 2012. Cox proportional hazard models were used to estimate the relative risks of mortality according to the level of diet quality and intakes of major nutrients. Indicators for diet quality index and nutritional intake status were assessed using MAR (mean adequacy ratio) and energy and protein intake level compared with the 2010 Korean DRI. Results: Higher diet quality/nutritional intake status were associated with lower mortality; the mortality risk (95% confidence interval) from all-cause of lowest MAR group vs highest was 1.66 (1.27 to 2.18) among ${\geq}30$ year old, and 1.98 (1.36 to 2.86) among 30~64 year old individuals. Those with below 75% of energy and protein intake of Korean DRI had higher mortality risks of all-cause mortality compared to the reference group. Diet quality/nutritional intake status was inversely associated with mortality from cardiovascular diseases and cancer. Conclusions: Poor Diet quality/nutritional intake status were associated with a higher risk of mortality from all-cause and mortality from cardiovascular diseases and cancer among South Korean adults.

• Atmosphere
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• v.27 no.2
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• pp.189-197
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• 2017

Progressing from weather forecasts and warnings to multi-hazard impact-based forecast and warning services represents a paradigm shift in service delivery. Urban flooding is a typical meteorological disaster. This study proposes support plan for urban flooding impact-based forecast by providing inundation risk matrix. To achieve this goal, we first configured storm sewer management model (SWMM) to analyze 1D pipe networks and then grid based inundation analysis model (GIAM) to analyze 2D inundation depth over the Gangnam drainage area with $7.4km^2$. The accuracy of the simulated inundation results for heavy rainfall in 2010 and 2011 are 0.61 and 0.57 in POD index, respectively. 20 inundation scenarios responding on rainfall scenarios with 10~200 mm interval are produced for 60 and 120 minutes of rainfall duration. When the inundation damage thresholds are defined as pre-occurrence stage, occurrence stage to $0.01km^2$, 0.01 to $0.1km^2$, and $0.1km^2$ or more in area with a depth of 0.5 m or more, rainfall thresholds responding on each inundation damage threshold results in: 0 to 20 mm, 20 to 50 mm, 50 to 80 mm, and 80 mm or more in the rainfall duration 60 minutes and 0 to 30 mm, 30 to 70 mm, 70 to 110 mm, and 110 mm or more in the rainfall duration 120 minutes. Rainfall thresholds as a trigger of urban inundation damage can be used to form an inundation risk matrix. It is expected to be used for urban flood impact forecasting.

• Journal of Environmental Health Sciences
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• v.40 no.5
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• pp.397-406
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• 2014

Objectives: Perchloroethylene (PCE) is a volatile chemical widely used as a solvent in the dry-cleaning and textile processing industries. It was evaluated as Group 2 "probably carcinogenic to humans" by the Integrated Risk Information System (IRIS) of the United State Environmental Protection Agency (U.S. EPA) in 2012. In order to provide a scientific basis for establishing risk management measures for chemicals on the national priority substances list, aggregate risk assessment was conducted for PCE, included in the top-10 substances. Methods: We conducted the investigation and monitoring of PCE exposure (e.g., exposure scenario, detection levels, and exposure factors, etc.) and assessed its multi-media (e.g., outdoor air, indoor air, and ground water) exposure risk with a deterministic and probabilistic approach. Results: In human risk assessment (HRA), the level of human exposure was higher in the younger age group. The exposure level through inhalation at home was the highest among the exposure routes. Outdoor air or uptake of drinking water represented less than 1% of total contributions to PCE exposure. These findings suggested that the level of risk was negligible since the Hazard Index (HI) induced by HRA was below one among all age groups, with a maximum HI value of 0.17 when reasonable maximum exposure was applied. Conclusion: In conclusion, it was suggested that despite low exposure risk, further studies are needed considering main sources, including occupational exposure.

• Earthquakes and Structures
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• v.9 no.3
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• pp.603-623
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• 2015

The scale and nature of the recent earthquakes in the world and the related earthquake disaster index coerce the concerned community to become anxious about it. Therefore, it is crucial that seismic lateral load effect will be appropriately considered in structural design. Application of seismic isolation system stands as a consistent alternative against this hazard. The objective of the study is to evaluate the structural and economic feasibility of reinforced concrete (RC) buildings with base isolation located in medium risk seismic region. Linear and nonlinear dynamic analyses as well as linear static analysis under site-specific bi-directional seismic excitation have been carried out for both fixed based (FB) and base isolated (BI) buildings in the present study. The superstructure and base of buildings are modeled in a 3D finite element model by consistent mass approach having six degrees of freedom at each node. The floor slabs are simulated as rigid diaphragms. Lead rubber bearing (LRB) and High damping rubber bearing (HDRB) are used as isolation device. Change of structural behaviors and savings in construction costing are evaluated. The study shows that for low to medium rise buildings, isolators can reduce muscular amount of base shears, base moments and floor accelerations for building at soft to medium stiff soil. Allowable higher horizontal displacement induces structural flexibility. Though incorporating isolator increases the outlay, overall structural cost may be reduced. The application of base isolation system confirms a potential to be used as a viable solution in economic building design.

• Journal of Gastric Cancer
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• v.16 no.2
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• pp.98-104
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• 2016

Purpose: The incidence of gallstones after gastrectomy for gastric cancer is higher than in the general population. However, the causes and mechanisms of post-gastrectomy gallstones are unclear. The aim of this study was to evaluate the incidence of gallstone formation and the risk factors for their development after gastrectomy for gastric cancer. Materials and Methods: Of 1,744 gastric cancer patients who underwent gastrectomy at Seoul National University Bundang Hospital between January 2010 and December 2012, 1,284 were included in this study and retrospectively reviewed. Patients' age, sex, body mass index (BMI), tumor location, stage, type of gastrectomy, type of reconstruction, and extent of node dissection were evaluated. Results: The incidence of gallstones after gastrectomy for gastric cancer was significantly higher in men than in women (P=0.019). Exclusion of the duodenum during reconstruction was associated with a significantly higher incidence of gallstones (P=0.003). Overweight and obese patients with BMI ${\geq}23kg/m^2$ had significantly higher incidence of gallstones than those with a lower BMI (P=0.006). Multivariate analysis showed that obesity (hazard ratio, HR=1.614; 95% confidence interval, CI: 1.135~2.296; P=0.008), male sex (HR=1.515, 95% CI: 1.029~2.231, P=0.033), and exclusion of the duodenum (HR=1.648, 95% CI: 1.192~2.280, P=0.003) were significant, independent risk factors for gallstones after gastrectomy. Conclusions: The cumulative incidence of gallstones for 5 years after gastrectomy was 15.3%. Male sex, obesity, and exclusion of the duodenum were risk factors for gallstone formation after gastrectomy. Careful surveillance will be required for these patient groups after gastrectomy.

• Journal of Biomedical Engineering Research
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• v.18 no.3
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• pp.233-241
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• 1997

The research on chromosomes is very significant in cytogenetics since genes of the chromosomes control revelation of the inheritance plasma. The human chromosome analysis is widely used to study leukemia, malignancy, radiation hazard, and mutagen dosimetry as well as various congenital anomalies such as Down's, Klinefelter's, Edward's, and Patau's syndrome. The framing and analysis of the chromosome karyogram, which requires specific cytogenetic knowledge is most important in this field. Many researches on automated chromosome karyotype analysis methods have been carried out, some of which produced commercial systems. However, there still remains much room to improve the accuracy of chromosome classification and to reduce the processing time in real clinic environments. In this paper, we proposed a hierarchical artificial neural network(HANN) to classify the chromosome karyotype. We extracted three or four chromosome morphological feature parameters such as centromeric index, relative length ratio, relative area ratio, and chromosome length by preprocessing from ten human chromosome images. The feature parameters of five human chromosome images were used to learn HANN and the rest of them were used to classify the chromosome images. The experiment results show that the chromosome classification error is reduced much more than that of the other researchers using less feature parameters.

• Environmental Analysis Health and Toxicology
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• v.26
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• pp.8.1-8.9
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• 2011

Objectives: This study assessed the health risks for children exposed to phthalate through several pathways including house dust, surface wipes and hand wipes in child facilities and indoor playgrounds. Methods: The indoor samples were collected from various children's facilities (40 playrooms, 42 daycare centers, 44 kindergartens, and 42 indoor-playgrounds) in both summer (Jul-Sep, 2007) and winter (Jan-Feb, 2008). Hazard index (HI) was estimated for the non-carcinogens and the examined phthalates were diethylhexyl phthalate (DEHP), diethyl phthalate (DEP), dibutyl-n-butyl phthalate (DnBP), and butylbenzyl phthalate (BBzP). The present study examined these four kinds of samples, i.e., indoor dust, surface wipes of product and hand wipes. Results: Among the phthalates, the detection rates of DEHP were 98% in dust samples, 100% in surface wipe samples, and 95% in hand wipe samples. In this study, phthalate levels obtained from floor dust, product surface and children's hand wipe samples were similar to or slightly less compared to previous studies. The $50^{th}$ and $95^{th}$ percentile value of child-sensitive materials did not exceed 1 (HI) for all subjects in all facilities. Conclusions: For DEHP, DnBP and BBzP their detection rates through multi-routes were high and their risk based on health risk assessment was also observed to be acceptable. This study suggested that ingestion and dermal exposure could be the most important pathway of phthalates besides digestion through food.