• Journal of Korean Society for Atmospheric Environment
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• v.31 no.2
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• pp.157-163
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• 2015

To establish National Reference Method (NRM) for $PM_{2.5}$, operational performance of 5 different commercial gravimetric-based $PM_{2.5}$ measuring instruments was assessed at Bulkwang monitoring station from January 23, 2014 to February 28, 2014. First, physical properties, design, and functional performance of the instruments were assessed. Evaluation was carried out to determine whether operating method for the instruments and levels of QA/QC activities meet the data quality objectives (DQOs). To verify whether DQOs were satisfied, reproducibility of QA/QC procedures, accuracy, relative sensitivity, limit of detection, margin of error, and coefficient of determination of the instruments were also evaluated. Results of flow rate measurement of 15 candidate instruments indicated that all the instruments met performance criteria with accuracy deviation of 4.0% and reproducibility of 0.6%. Comparison of final $PM_{2.5}$ mass concentrations showed that the coefficient of determination ($R^2$) values were greater than or equal to 0.9995, and concentration gradient ranged from 0.97 to 1.03. All the instruments satisfied criteria for NRM with the estimated precision of 1.47~2.60%, accuracy of -1.90~3.00%, and absolute accuracy of 1.02~3.12%. This study found that one particular type of measuring instrument was proved to be excellent, with overall evaluation criteria satisfied.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.5
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• pp.1-14
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• 2015

In case of a gas turbine engine for supersonic operation, the engine have a wide range of operating inlet mass flow rate and required high performance such as thrust and fuel consumption. Therefore, variable system and its optimal control logic are essentially needed. In this work, a method for performance prediction of a gas turbine engine with variable system compressor and its control scheme were developed. Conceptual design of compact acuation system for the operation of the variable system was also conducted. The performance of a low-bypass ratio mixed flow turbofan engine was analyzed, and it was observed that the surge margin of the engine is improved at off-design condition by applying the control scheme.

• Health Policy and Management
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• v.18 no.4
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• pp.148-169
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• 2008

As the Korean Government began to perceive healthcare as one of foundational industries for national dynamics, there has been mounting advocacy for the introduction of for-profit hospitals with a view to bringing efficiency in healthcare services industries and improvement of their international competitiveness. The Government is now considering the issue from all angles in favor of permitting for-profit hospitals. However, There have been few precedent studies on this subject to provide helpful data for the discussion and in the health policy making. This study used private hospitals - for-profit and nonprofit - in Florida, USA as study subjects to accumulate basic data that may be utilized for those involved in debates and health policy making relating to the introduction of for-profit hospitals in Korea. Among all the private general hospitals in Florida, those surveyed by AHA(American Hospital Association) for four consecutive years from 2001 and 2004 and others reported about to MCR(Medicare Cost Report) included in the collected data for analysis. In total 139 private general hospitals consisting of 73 for-profit hospitals and 66 nonprofit hospitals were included in the collected analysis data. Results of analysis revealed no significant difference between for-profit hospitals and nonprofit hospitals in the usage aspects of healthcare services including the average length of stay and the ratio of Medicare vs Medicaid patients. However, financial performances indicated by such factors. as the pre-tax return on assets and the pre-tax operating margin showed to be significantly higher in for-profit hospitals compared with nonprofit hospitals. And the ratio of personnel expenses and the turn period of total assets showed to be significantly lower in for-profit hospitals. Based on the hypothesis that arguments about the introduction of for-profit hospitals have considerably different viewpoints depending on the size of hospital represented by the number of bed, these two hospital types were compared again using the number of beds as a controlled factor, but the results were similar. We, therefore, could conclude that the for-profit hospitals in Florida included in this study could, in their for-profit operation, improve their financial performance by pursuing cost reduction and effectively utilizing their assets without limiting the amount and the range of their services or avoiding less medically protected groups such as Medicare and Medicaid patients.

• Journal of Korean Society for Atmospheric Environment
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• v.7 no.1
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• pp.55-65
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• 1991

The study was performed to select a adaptable tree species under stressed field conditions where there are a industrial plants operating with a number of smoke stacks emitting pollutants, such as hydrogen fluoride and sulfur dioxide. As a result of the study, a tree species selected are due to construct a forest belt in a zones near industrial plants to reduce the concentrations of air pollutants. The concentrations of atmospheric hydrogen fluoride and sulfur dioxide were very higher at experimental sites near industrial plants (air-pollution sites) than at control site. The leaves of 7 tree species grown at air pollution sites contained more sulfur and, specially, fluorine than at those control site. Among the tested tree species, Ligustrum japonicum Thunb. and Euonymus japonica Thunb. grown at air pollution sites did not at all break out a foliar injury but appeared to be healthy, as well as those grown at control site. Acer pseudo-sieboldianum Kom., Pinus virginiana Mill., Larix leptolepis Gordon., Pinus koraiensis Sieb. et Zucc., Pinus strobus L., Picea abies Karst and Ligustrum obtusifolium Sieb. et Zucc., however, showed a severe fluoride-type foliar injury such as necrosis on tip or margin of leaves, etc. Fluorine found in leaves was proved to be correlated to sulfur found in leaves whereas index of foliar injury hadn't a good correlation to pollutants found in leaves. It appears that Euonymus japonica Thunb., Ligustrum japonica Thunb., Platanus acerifolia Willd, Chamaecyparis pisifera Endl., Populus tomentiglandulosa T. Lee and Sophora japonica L. grown at both experimental sites had a high value of percent survival whereas Pinus virginiana Mill., Pinus koraiensis Sib. et Zucc., Koelreuteria paniculata Laxm. and Alnus hirsuta Rupr. had an extremely low value of that. In comparison with control site, the percent tree height increments in Chamaecyparis pisifera Endl., Ligustrum japonicum Thunb., Quercus acutissima Carruth., Populus tomentiglandulosa T. Lee, Pinus thunbergii Parl and Euonymus japonica Thunb. and the percent upmost root diameters in Populus tomentiglandulosa T. Lee, Chamaecyparis pisifera Endl., Euonymus japonica Thunb., Ligustrum japonicum Thunb., Betula platyphylla var. japonica Hara and Pinus thunbergii Parl. cultivated at air polluted sites showed very high value above 90%, respectively. A significant negative correlation (r=-0.662) was recognized between the index of foliage injury and the percent collective character, which was the mean of tree characters such as percent survival, percent tree height increment and percent upmost root diameter increment which compared to those at air polluted site with those at control site. Based on the percent collective character Ligustrum japonicum Thunb., Euonymus japonica Thunb., Chamaecyparis pisifera Endl., Populus tomentiglandlosa T. Lee, Betula platyphyla var. japonica Hara and Platanus occidentalis L. have large value about 90%, respectively. Therefore, the results indicate that this tree species are adaptable species in air polluted regions. For better understanding of the adaptable tree species, furthur studies concerning the effects of various air pollutants on the tree growth are required.

• Archives of Plastic Surgery
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• v.36 no.4
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• pp.512-515
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• 2009

Purpose: Neurofibromatosis(NF) is an autosomal - dominant systemic disease. Up to fifty percent of patients with NF are reported to have concomitant vascular abnormalities. In the resection of a larger NF, the risk of uncontrolled hemorrhage is much higher due to the difficulty of hemostasis of large vessels within the tumor. We ligated the base of the giant NF with a simple loop - shaped ligation before removal of the giant NF in both buttocks. And then we could successfully reduce the amount of hemorrhage during the operation. Methods: A 46 - year - old female patient presented for giant masses of both gluteal area, which has been growing slowly for the last ten years. Each mass was about $30{\times}20cm$ in size. After designing the elliptical resection margin, we tightened the tumor base by using continuous loop - shaped suture ligation(weaving the thread up and down in a loop - shaped pattern, leaving a space of 2 cm between each loop) with a straight needle and prolene 2 - 0. After skin incision, we proceeded the dissection toward the central and inferior side of the mass obliquely while we avoided breaking large vascular sinuses. We resected the tumor in a wedged - shape. Subcutaneous tissue was sutured layer by layer and skin was closed by vertical mattress and interrupted suture. The loop - shaped ligation of the base was removed and compressive dressing was done with gauzes and elastic bandages. Results: Postoperative complications such as infection, hemorrhage, hematoma, and dehiscense did not occur. Perioperatively the patient was sufficiently transfused with five units of blood and two units of fresh frozen plasma. During the subsequent 1 year follow - up, the functional and cosmetic result was excellent. Conclusion: A continuous loop - shaped suture ligation procedure along the base of the giant NF effectively reduced the amount of hemorrhage during the operation, made dissection and ligation of vessels easily and quickly, and shorten the operating time and postoperative recovery time.

• Journal of Energy Engineering
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• v.24 no.2
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• pp.129-143
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• 2015

Increasing concerns on climate change and energy security accelerated policies to reduce green-house gas emission, especially from the transportation sector. Electric vehicle (EV) has been on the spotlight to deal with such environmental issue and V2G (Vehicle-to-Grid) technology began to draw attentions as an alternative to reduce ownership costs while contributing to an efficient and decentralized power grid. This study conducts a scenario analysis on total cost of ownership of EV under V2G scheme and compare with non-V2G EV and Internal Combustion Engine (ICE) vehicle. As result, V2G service is expected to provide an annual average profit of $210 to EV users willing to reverse flow its residual power in the battery. The profit from V2G service leaves a margin of $4,530 over operational lifetime, compared with $2,420 cost of charge for non-V2G EV. In summary, total cost of ownership of V2G-capable EV was 6.2% less than non-V2G EV and 10.2% higher than ICE vehicle. The results confirm a comparative economic advantage of operating EV under V2G scheme. Increased number of EVs with V2G service has shown to provide positive effects to power industry for valley filling in load distribution, thus, favorably increasing the overall economic feasibility.

• Radiation Oncology Journal
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• v.36 no.2
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• pp.139-146
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• 2018

Purpose: IBTR! 2.0 nomogram is web-based nomogram that predicts ipsilateral breast tumor recurrence (IBTR). We aimed to validate the IBTR! 2.0 using an external data set. Materials and Methods: The cohort consisted of 2,206 patients, who received breast conserving surgery and radiation therapy from 1992 to 2012 at our institution, where wide surgical excision is been routinely performed. Discrimination and calibration were used for assessing model performance. Patients with predicted 10-year IBTR risk based on an IBTR! 2.0 nomogram score of <3%, 3%-5%, 5%-10%, and >10% were assigned to groups 1, 2, 3, and 4, respectively. We also plotted calibration values to observe the actual IBTR rate against the nomogram-derived 10-year IBTR probabilities. Results: The median follow-up period was 73 months (range, 6 to 277 months). The area under the receiver operating characteristic curve was 0.607, showing poor accordance between the estimated and observed recurrence rate. Calibration plot confirmed that the IBTR! 2.0 nomogram predicted the 10-year IBTR risk higher than the observed IBTR rates in all groups. High discrepancies between nomogram IBTR predictions and observed IBTR rates were observed in overall risk groups. Compared with the original development dataset, our patients had fewer high grade tumors, less margin positivity, and less lymphovascular invasion, and more use of modern systemic therapies. Conclusions: IBTR! 2.0 nomogram seems to have the moderate discriminative ability with a tendency to over-estimating risk rate. Continued efforts are needed to ensure external applicability of published nomograms by validating the program using an external patient population.

• Management & Information Systems Review
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• v.31 no.4
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• pp.33-56
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• 2012

The purposes of this paper are analysed the relationship between environmental regulation and financial performance in Korea. The financial performance of listed companies and Outside Auditing firms was evaluated by logistic regression. First, R&D investment is proportionally correlated with the ability to comply with environmental regulations. It can be explained increase of investment in R&D causes enhancement of compliance of environmental regulations with development of environmental technology. Second, statistical significance is not observed between financial aspects such as current ratio, debt-to-equity ratio, cash flow, and operating profit margin and the ability to comply with environmental regulations. It indicates high financial performance could not directly lead investment for the ability of that. Third, in terms of structural aspects, firm size and employees have a reliable correlation with compliance with environmental regulations due to high attention of larger firms for PR, and IR, while capital intensity and gravity, and exports do not. Finally, violation of environmental regulations is not affect by the controlling shareholder ownership.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.614-623
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• 2017

The purpose of this study is to analyze the impact of the financial performance of regional public hospitals on their efficiency. In addition, the analysis of their efficiency using environmental factors, such as the market share, operating mode, and size of the regional public hospitals, as well as the factors influencing their efficiency, are selected by selecting the input and output factors of the hospitals and some differences were found between them. The DEA index and financial performance of the 31 regional public hospitals were calculated for the three years from 2012 to 2014. ANOVA and hierarchical regression analysis were used. As a result, there was a significant difference in their efficiency according to the environmental factors, such as the city scale of the regional public hospital, the number of hospital beds, and their business performance, productivity, and publicness. The medical profit margin (p<0.05), labor cost investment efficiency (p<0.05) and HHI (p<0.05) were found to affect the efficiency. In order to identify the inefficiencies of the regional public hospitals and increase their efficiency, it is necessary to measure the efficiency of the input resources and to reduce their cost. In addition, if the regional public hospitals were to provide specialized services, such as specialized functions of medical care that would give them a competitive advantage over private hospitals, their operational efficiency would be enhanced and they would be able to fulfill their role as public medical institutions.

• Journal of Digital Convergence
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• v.17 no.3
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• pp.261-269
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• 2019

The purpose of this study is to present the effective management strategy of RI based on the results of research on the causal relationship between the regional medical care capacity and the hospital management performance by calculating the RI of the general hospitals in Korea, This research has significance. The results of this study are as follows: First, statistically significant differences were found in Number of beds and recurring profits in urban areas by the general characteristics. Second, the correlations between the RI and the variables of the regional medical use are as follows: Recurring profit ratio, New Outpatient Visits, Operating Margin, Daily Outpatient Visits per 100 Beds, Daily Inpatient Days per 100 Beds, and Average Charge per Inpatient Day. Based on the results of this study, the significance of this study is as follows. First, we calculated the affinity for local medical use, which is the index of local medical utilization. Secondly, it is analyzed according to internal and external environmental factors such as city size, hospital size, etc. It can be said that the hospital provided basic data for establishment of hospital management strategy to increase the utilization rate of local medical care.