• Journal of Korean Society on Water Environment
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• v.24 no.4
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• pp.499-503
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• 2008

In order to control the non-point source pollution, a vegetative filter strips (VFS) was set up and the site-monitoring was performed. The objective of this study is to investigate the influence of the plant coverage on treatment efficiency of total nitrogen (T-N) and total phosphorus (T-P) using vegetative filter strips. According to the results, it seemed that the treatment efficiencies of T-N and T-P were closely related with the plant coverage ratio. The results showed that treatment efficiency of T-P average 50% at higher than 50% of the plant coverage and 20~23% at lower than 50% of the plant coverage. Also, the treatment efficiency of T-N increased with the increase of the plant coverage ratio.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.8
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• pp.3617-3619
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• 2012

Background: The completeness of cancer registration is a major validity index of any reported cancer incidence. The present study aimed to evaluate the esophageal cancer incidence registered in the Tehran Metropolitan Area Cancer Registry. Materials and methods: The data on esophageal cancer abstracted from three sources of 1) pathology departments, 2) medical records, and 3) death certificates during 2003 till 2007 were utilized. The completeness of the data sources were evaluated using coverage (defined as the proportion of a community population with esophageal cancer identified by the source) and density (defined as the proportion of non-empty fields of the data by source). Results: A total 1,404 cases of esophageal cancer were reported for the duration of the study. Pathology provided 771, medical records 432, and death certificates 609. The coverage was 0.55 for pathology, 0.31 for medical records, and 0.43 for death certificates. The respective density values were 0.82, 0.96 and 0.98, respectively. Pathology (0.45) was the most complete source followed by medical records (0.42), and death certificates (0.29). Discussion: A low degree of completeness dictates putting more effort into case finding plus abstracting data more thoroughly.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.61-61
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• 2010

By using high resolution x-ray photoelectron spectroscopy, we show that inelastic scattering of photoelectron at low temperature (30K~50K) generates two kinds of oxygen species on Pt (111) surface. Intense synchrotron radiation source dissociates oxygen molecules into chemisorbed atomic oxygen and induces the formation of PtO on surface. Estimated coverage of dissociated atomic oxygen is 0.5 ML, suggesting possible formation of p($2{\times}1$) surface structure, while PtO coverage shows saturation coverage of 0.5 ML. Molecular oxygen dosed at 30 K undergoes thermally activated transition from physisorbed to chemisorbed state at around 40K.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.4
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• pp.47-52
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• 2009

The transmitted signal from a source is transmitted to a destination through wireless channels. But if the mobile destination is out of the coverage of the source or exists in the shady side of the coverage, the destination can not receiver the signal from the source and they can not maintain communication. In order to overcome these problems, we adopt relays. A system employing relays is a multi-hop relay system. In the multi-hop relay system, coverages of each relay that is used for different systems can overlap each other in some place. When there is a destination in this place, interference occurs at the destination. In this paper, we study on the efficient co-channel interference (CCI) cancellation algorithm. In the proposed strategy, CCI is mitigated by zero forcing (ZF) or minimum mean square error (MMSE) receivers. Moreover, successive interference cancellation (SIC) with optimal ordering algorithm is applied for rejecting CCI efficiently. And we analyzed and simulated the proposed system performance in Rayleigh fading channel. In order to justify the benefit of the proposed strategy, the overall system performance is illustrated in terms of bit error probability.

• Journal of Korean Society for Geospatial Information Science
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• v.1 no.1 s.1
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• pp.171-180
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• 1993

Concern about nonpoint source pollution associated with urban storm water has led to the development of new tools for better water quality planning. This paper presents an application of a geographic information system (GIS) for urban water quality study. The GIS was used to manage land use data for nonpoint source pollution modeling and to aggregate pollutant loadings within various types of geographic units. An empirical water quality model was used to estimate pollutant loadings based primarily on land use. A land use coverage was created by updating an old coverage through interpretation of recent photography. This land use coverage was also used to record all pollutant loadings for each land use polygon. Storm sewer maps were digitized and interpreted to create a coverage of storm sewer basins and sub-basins. By overlaying pollutant loadings with the sewer sub-basin layer, aggregated pollutant loadings for major sewer outfalls were calculated. Based on the loading information, critical areas of excessive pollutant loadings were located and the effectiveness of Best Management Practices (BMPs) to control pollutant loadings were evaluated.

• Korean Journal of Radiology
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• v.21 no.1
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• pp.58-67
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• 2020

Objective: Third-generation dual-source computed tomography (3rd-DSCT) allows dynamic myocardial CT perfusion imaging (dynamic CTP) with a 10.5-cm z-axis coverage. Although the increased radiation exposure associated with the 50% wider scan range compared to second-generation DSCT (2nd-DSCT) may be suppressed by using a tube voltage of 70 kV, it remains unclear whether image quality and the ability to quantify myocardial blood flow (MBF) can be maintained under these conditions. This study aimed to compare the image quality, estimated MBF, and radiation dose of dynamic CTP between 2ndDSCT and 3rd-DSCT and to evaluate whether a 10.5-cm coverage is suitable for dynamic CTP. Materials and Methods: We retrospectively analyzed 107 patients who underwent dynamic CTP using 2nd-DSCT at 80 kV (n = 54) or 3rd-DSCT at 70 kV (n = 53). Image quality, estimated MBF, radiation dose, and coverage of left ventricular (LV) myocardium were compared. Results: No significant differences were observed between 3rd-DSCT and 2nd-DSCT in contrast-to-noise ratio (37.4 ± 11.4 vs. 35.5 ± 11.2, p = 0.396). Effective radiation dose was lower with 3rd-DSCT (3.97 ± 0.92 mSv with a conversion factor of 0.017 mSv/mGy∙cm) compared to 2nd-DSCT (5.49 ± 1.36 mSv, p < 0.001). Incomplete coverage was more frequent with 2nd-DSCT than with 3rd-DSCT (1.9% [1/53] vs. 56% [30/54], p < 0.001). In propensity score-matched cohorts, MBF was comparable between 3rd-DSCT and 2nd-DSCT in non-ischemic (146.2 ± 26.5 vs. 157.5 ± 34.9 mL/min/100 g, p = 0.137) as well as ischemic myocardium (92.7 ± 21.1 vs. 90.9 ± 29.7 mL/min/100 g, p = 0.876). Conclusion: The radiation increase inherent to the widened z-axis coverage in 3rd-DSCT can be balanced by using a tube voltage of 70 kV without compromising image quality or MBF quantification. In dynamic CTP, a z-axis coverage of 10.5 cm is sufficient to achieve complete coverage of the LV myocardium in most patients.

• Journal of Preventive Medicine and Public Health
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• v.23 no.2 s.30
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• pp.185-193
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• 1990

The purpose of this study is to observe the pattern of change in medical care utilization over time in early years of insurance coverage. The source of data is the benefit records file of a voluntary medical insurance society for covering the four-year period, from 1982 to 1985. The measure of medical care utilization used in this study is the age-sex standardized percentage of the enrollee who have visited a physician over total analytical population during a three-month period. For six cohorts by the year of enrollment ($1979{\sim}1984$), the relationship between the utilization and duration of insurance coverage was examined controlling for the calender year and season. In the analysis, logistic multiple regression and residual analysis were employed. It was observed that medical care utilization rapidly increased during the early stage of insurance coverage, and after then increased at a slower rate over time to become almost stable in about twenty months.

• Safety and Health at Work
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• v.2 no.2
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• pp.148-157
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• 2011

Objectives: Although compensation for occupational injuries and diseases is guaranteed in almost all nations, countries vary greatly with respect to how they organize workers' compensation systems. In this paper, we focus on three aspects of workers' compensation insurance in Organization for Economic Cooperation and Development (OECD) countries - types of systems, employers' funding mechanisms, and coverage for injured workers - and their impacts on the actual frequencies of occupational injuries and diseases. Methods: We estimated a panel data fixed effect model with cross-country OECD and International Labor Organization data. We controlled for country fixed effects, relevant aggregate variables, and dummy variables representing the occupational accidents data source. Results: First, the use of a private insurance system is found to lower the occupational accidents. Second, the use of risk-based pricing for the payment of employer raises the occupational injuries and diseases. Finally, the wider the coverage of injured workers is, the less frequent the workplace accidents are. Conclusion: Private insurance system, fixed flat rate employers' funding mechanism, and higher coverage of compensation scheme are significantly and positively correlated with lower level of occupational accidents compared with the public insurance system, risk-based funding system, and lower coverage of compensation scheme.

• Membrane and Water Treatment
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• v.10 no.1
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• pp.57-65
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• 2019

This study assessed the contribution of emergent vegetation (Phragmites australis, Typha latifolia, and Nelumbo nucifera) to the submerged surface area, the amount of biofilms attached to the submerged portions of the plants, and the treatment performance of a free water surface (FWS) constructed wetland. Results showed that a 1% increase ($31m^2$) in the vegetative area resulted in an increase of $220m^2$ of submerged surface area, and 0.48 kg Volatile Suspended Solids (VSS) of attached biofilm. As the vegetation coverage increased, effluent organic matter and total Kjeldahl nitrogen decreased. Conversely, a higher nitrate concentration was found in the effluent as a result of increased nitrification and incomplete denitrification, which was limited by the availability of a carbon source. In addition, a larger vegetation coverage resulted in a higher phosphorus in the effluent, most likely released from senescent biofilms and sediments, which resulted from the partial suppression of algal growth. Based on the results, it was recommended that constructed wetlands should be operated with a vegetation coverage of just under 50% to maximize pollutant removal.

• Korean Journal of Ecology and Environment
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• v.38 no.3 s.113
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• pp.393-402
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• 2005

The field scale experiment was performed to examine the effect of plant coverage on the constructed wetland performance and recommend the optimum development and management of macrophyte communities. Four sets (each set of 0.88 ha) of wetland (0.8 ha) and pond (0.08 ha) systems were used. Water flowing into the Seokmoon estuarine reservoir from the Dangjin stream was pumped into wetland system. Water depth was maintained at 0.3 ${\sim}$ 0.5 m and hydraulic retention time was managed to about 2 ${\sim}$ 5 days; emergent plants were allowed to grow in the wetlands. After three growing seasons of the construction of wetlands, plant coverage was about 90%, even with no plantation, from bare soil surfaces at the initial stage. During the start up period of constructed wetlands, lower water levels should be maintained to avoid flooding newly plants, if wetland plants are to be started from germinating seeds. Effluent T-N concentration in low plant coverage wetland was higher in winter than high plant coverage wetland, whereas no T-P effluent concentration and removal efficiency difference was observed within 15% plant coverage. Dead vegetation affected nitrogen removal during winter because it is a source of organic carbon which is an essential parameter in denitrification. Biomass harvesting is not a realistic management option for most constructed wetland systems because it could only slightly increase the removal rate and provide a minor nitrogen removal pathway due to lack of organic carbon.