• Particle and aerosol research
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• v.14 no.4
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• pp.171-180
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• 2018

To optimize the shape of the electrostatic precipitator for the removal of particulate matter in subway environments, the wind-tunnel experiments were carried out to characterize collection efficiency and ozone emission rate. As a standardized parameter, power consumption divided by the square of flow velocity, was increased, the $PM_{10}$ collection efficiency increased. If the standardized parameter is higher than 1.0 due to high power consumption or low flow velocity, increase in thickness of electrodes from 1 to 2 mm, or increase in distance of collection plates from 5 to 10 cm did not change the $PM_{10}$ collection efficiency much. Increase in thickness of high-voltage electrodes, however, can cause decrease in $PM_{10}$ collection efficiency by 28% for low power consumption and high flow velocity. The ozone emission rate decreased as distance of collection plates became wider, because the ozone emission rate per unit channel was constant, and the number of collection channels decreased as the distance of collection plates increased. When the distance of collection plates was narrow, the ozone emission rate increased with the increase of the thickness of electrodes, but the difference was negligible when the distance of collection plates was wide. It was found that the electrostatic precipitator having a thin high-voltage electrodes and a narrow distance of collection plates is advantageous. However, to increase the thickness of high-voltage electrodes, or to increase the distance of collection plates is needed, it is necessary to increase the applied voltage or reduce the flow rate to compensate reduction of the collection efficiency.

• Particle and aerosol research
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• v.12 no.1
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• pp.11-20
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• 2016

A large amount of wear dust generated during train operation is a major dust source in urban railway tunnels. To check possibility of a louver dust collector for the removal of dust in the railway tunnel, five louver dust collector models were designed and their performance was tested in a wind tunnel. JIS Z 8901 Class 8 dust was used as a test dust. Pressure drop and particle collection efficiency were evaluated with the face velocity ranging from 1 m/s to 4 m/s. At this low velocity range, particle collection efficiency of the louver dust collector was found to be insensitive to air velocity and design parameters. Pressure drop was under 40 Pa, and $PM_{10}$ and $PM_{2.5}$ collection efficiencies were approximately 50% and 30%, respectively.

• Health Policy and Management
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• v.23 no.1
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• pp.78-89
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• 2013

This study empirically analyze efficiency and productivity changes of public hospitals of Korea using data envelopment analysis/Window model and global Malmquist indices model. We use the ten-year data from 2001 to 2010 of 30 regional public hospitals listed database from the Association of Korean Regional Public Hospitals. The main focuses are to reveal whether the technical inefficiency are improved as time goes by, and efficiency and productivity are affected by environmental factors. The results can be summarized as follows. First, the efficiencies of public hospitals rise in trend as time passes. Second, regional public hospitals show the different average efficiencies according to their regional type, hospital type, operational type, medicaid type, and demand and supply conditions by Mann-Whitney U-tests. Third, technical efficiency changes mainly contribute to 4.4% annual average growth rate of productivity of regional public hospitals during that period. Our findings have some policy implications. It is confirmed that there exist some environmental inefficiencies, and those inefficiencies can not be overcome through just improving the inner management system. Thus, policy and institutional changes are necessary for regional public hospitals to improve efficiency and productivity overall.

• Journal of Home Health Care Nursing
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• v.25 no.1
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• pp.67-77
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• 2018

Purpose: The purpose of this study was to compare the efficiency of general ward nurses in hospitals using Data Envelopment Analysis (DEA). Methods: Participants were 30 nurses working at a general ward. Input variables were labor cost and time of direct nursing. Output variables were prevention rate of medication error and bedsores, and patient satisfaction. These variables were extracted using literature review and CVI of an expert group. Data were collected from September 18 to October 7, 2017. Data were analyzed using EMS 3.1 program for DEA and descriptive statistics. Results: The average efficiency score of 30 nurses was 0.986, which was very high over all. In the super-efficiency analysis of 11 nurses, their efficiency ranged from 1.0 to 1.047. In addition, when the current output was fixed, the labor cost of nurses did not affect efficiency. Conclusion: This study attempted a new approach concerning performance evaluation of nurses using DEA. This method was useful during appraisal of nurses. We suggest that various input and output variables that were not considered in this study should be added to develop a integrative performance analysis model for nurses.

• Journal of Environmental Impact Assessment
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• v.14 no.3
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• pp.109-115
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• 2005

This study was conducted to evaluate the efficiency of indoor air cleaners and to inform how to select them correctly to the users. The efficiencies of removing suspended bacteria per hour were $64.3{\pm}13.1%$ for filter, wet, and complex type, respectively, which showed the complex type was the most efficient. The removal efficiencies of formaldehyde (HCHO) after two hours operation of air cleaners showed 88.3% and 81.1% for filter and wet type, respectively. The efficiency of complex type, with removal rate of 55.5~58.4%, was decreased after 30 minutes operation. Therefore, it is recommended to perform over 60 minutes when doing air cleaner certification test for HCHO removal efficiency. Generally, air cleaners having low wind volume showed higher efficiency. All tested air cleaners had no potential for removing of volatile organic compounds (VOCs), which is toxic substances, and it is desirable to develop a device which can control these substances. The results also confirmed that there was no ozone production from all tested air cleaners. And it is recommended to ventilate for 20 minutes every four hours to maintain 50% ventilation status.

• Journal of Environmental Health Sciences
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• v.26 no.4
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• pp.9-14
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• 2000

In this study, the removal efficiencies of organics, nitrogens and phosphorus from municipal wastewater using $A^2$/O process were investigated. BO $D_{5}$ removal efficiencies were indicated 95% and 94% with HRT of 12 hr and 10 hr, respectively. CO $D_{Cr}$ average removal efficiency and concentration of effluent were indicated 87% and 34mg/$\ell$. SS average removal efficiency and concentration of effluent were indicated 93% and 4~17mg/$\ell$. T-N removal efficiency and concentration of effluent were shown as 60~80% and below 15mg/$\ell$. In aerobic basin, removal efficiency of N $H_4$-N was shown over 97% with N $H_4$-N volume load 0.16kg N $H_4$-N/㎥.d and in anoxic basin, denitrification efficiency was indicated over 80% with return sludge rate 0.5Q and internal recirculation rate 2.5Q. Removal efficiency and effluent concentration of phosphorus were shown over 80% and below 2 mg/$\ell$ with return sludge rate 0.5Q.Q.

• The Korean Journal of Food & Health Convergence
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• v.6 no.6
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• pp.17-23
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• 2020

The main task of agro-industrial production is to provide the population with food products for the production of which energy is expended in the form of electricity, technical means, fuels and lubricants, mineral fertilizers, etc. Accordingly, we have developed a concept and general methodological principles for the analysis of ecological and biotechnical systems in animal husbandry, it makes it possible to simulate the influence of various factors on the energy and ecological efficiency of systems, to compare and search for energy-saving modes and technologies. General methodological principles have been developed for the analysis of energy efficiency and environmental safety of agricultural ecological and biotechnical systems, which are based on the definition of the bioenergy efficiency coefficient, the quantitative expression of which is the ratio of energy accumulated in products to the total energy consumption for its production. This makes it possible to model with sufficient accuracy the influence of various factors on the energy and environmental efficiency of the system, to compare and search for energy-saving modes and technologies in order to find and select the most energy efficient ones to increase the energy efficiency of the complex.

• Journal of Wellbeing Management and Applied Psychology
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• v.6 no.1
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• pp.17-22
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• 2023

Purpose: VOCs (volatile organic compounds) are all the organic compounds that react with solar rays and increase the concentration of ozone in the troposphere and are partially also known as carcinogens. The adsorption using activated carbon is usually applied to remove VOCs. Research design, data and methodology: The 20 places of surface coating facilities were selected to evaluate the emission amount of VOCs in Seoul. In addition, the removal efficiency of VOCs in 25 places of automobile coating facilities was evaluated. Results: The average emission amount of VOCs was 10.903 kg/hr from automobile coating facilities, while 3.520 kg/hr from other surface coating facilities. The removal efficiency in adsorption with the combustion catalytic process has the mean value of 87.9% and the regeneration efficiency of activated carbon has the mean value of 95.0%. Conclusions: The removal efficiency in adsorption with the biofiltration process has the mean value of 89.8% and the regeneration efficiency of activated carbon has the mean value of 94.8%. The removal efficiency in the plasma catalyst process has the mean value of 79.3%.

• Korea Journal of Hospital Management
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• v.13 no.3
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• pp.69-93
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• 2008

Rising healthcare cost is a global phenomenon that justifies governments' introduction of 'incentive regulation' plan for the improvement of hospital efficiency. A number of previous studies tried to evaluate the efficiency of healthcare organization by using Data Envelopment Analysis(DEA), a common efficiency benchmarking method. However, there is a concern that this kind of efficiency evaluation could induce "quantity-quality trade-off". Moreover, as quality aspect is especially important in terms of 'effectiveness' of health care, it should be considered in efficiency evaluation of healthcare organization. A number of different models were tried so far to incorporate quality aspect into DEA, however, none is universally recognized as a standard. Thus, in this study, previous quality-incorporating DEA models were categorized into 6 types according to the way of incorporating quality aspect, and strengths and limitations of each type were reviewed with a set of artificial data as an example. Based on this review, a new quality-incorporating efficiency evaluation model, named Quality-adjusted output DEA(QAO-DEA), was suggested. As an exploratory empirical analysis, technical efficiency of human resource were measured with different quality-incorporating DEA models, using 2004 data from National University Hospitals. In conclusion, Quality-adjusted output DEA(QAO-DEA) model seems to be one of the most desirable alternatives to incorporate quality aspect in efficiency evaluation of hospital, and deserves the consideration as a policy tool to induce simultaneous improvement of both efficiency and quality.

• Journal of Environmental Health Sciences
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• v.37 no.1
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• pp.64-72
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• 2011

This study was performed to assess the removal efficiency on nitrogen, phosphorus and organic carbon in wastewater by spatial separation and internal recycling in a modified oxidation ditch process (modified OD). The performances of the modified OD were evaluated via laboratory-scale experiments. The process was operated at hydraulic retention times of 6-48 hours and solid retention times of 17-38 days. We found that organic carbon removal efficiency increased after the modified OD operation period. T-N removal efficiency remained stable; average T-N concentration of effluent was 8.02 mg/l after modified OD operation. In contrast, T-P concentration of effluent was over 1 mg/l. Nitrogen and phosphorus removal efficiency of modified OD at HRT 12 hr were 83.1% and 74.1%, respectively. Also, maximum efficiency was found at SRTs from 20 to 30 days. T-N removal efficiency was 83.1% at a C/N ratio from 3.0 to 3.5. However, T-N removal efficiency decreased at C/N ratios over 3.5. Also, T-P removal efficiency increased with HRT at C/P ratios in the same condition. Maximum efficiency was 74.1% at a C/P ratio from 25 to 28. T-N removal efficiency was 79.2% and T-P removal efficiency was 65.3% after M4 mode operation (added to the internal recycle line connected to the anoxic reactor). The modified OD with spatial separation and internal recycling developed in this study is, therefore, believed to be an improvement for solving problems in the nutrient removal technologies.