• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.1
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• pp.107-114
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• 2020

This paper studies a method for estimating the scale of a Hadoop cluster to process big data as a cost-effective manner. In the case of medical institutions, demands for cloud-based big data analysis are increasing as medical records can be stored outside the hospital. This paper first analyze the Amazon EMR framework, which is one of the popular cloud-based big data framework. Then, this paper presents a efficiency model for scaling the Hadoop cluster to execute a Mapreduce application more cost-effectively. This paper also analyzes the factors that influence the execution of the Mapreduce application by performing several experiments under various conditions. The cost efficiency of the analysis of the big data can be increased by setting the scale of cluster with the most efficient processing time compared to the operational cost.

• The Korean Journal of Health Service Management
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• v.9 no.1
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• pp.17-29
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• 2015

This study, an examination of the plan for effective resource management for national university hospitals, was performed to determine the relationship between the effectiveness of patient output by considering input personnel using the DEA model and Management Performance, in which 4 years of data from 12 national university hospitals were analyzed. Among the components of the effectiveness, utilizing properly imput components from the application of VRS(Variable Returns to Scale), the Management Performance of national university hospitals was found to be affirmatively influenced by PTE(Pure Technical Efficiency). Regarding the Management Performance of national university hospitals in their attempts to establish a plan for effective human resource management, the management of patient numbers on the basis of calculation level with input is more recommendable than the controlling of personnel input using patient numbers. Thus, the establishment of a strategy plan for the proper allocation of administrative staff and sickbeds, considering the variation of patient numbers, is suggested.

• Journal of Environmental Health Sciences
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• v.29 no.1
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• pp.74-83
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• 2003

Microcystin, stable compounds with circular heptapeptides, is presented inside cyanobacterial cell. So far, over 30 types have been known to exist and microcystin-LR, RR among them are the most potent toxin compound. By this reason, a strong oxidant, ozone was used in this study to remove the microcystins produced by cyanobacteria. Removal efficiency of microcystin at M water treatment plant was also evaluated. Microcystin concentration was determined by protein phosphatase inhibition assay. The results showed that dissolved microcystin in raw water detected in the range of 0.011-0.028 ㎍ Microcystin-RR equivalent/l. Above 98% of microcystin was removed through overall treatment system. Therefore, the water treatability of M treatment plant seemed to be excellent. Removal efficiency of microcystin according to unit process varied as characteristics of raw water such as DOC, UV/sub 254/ and turbidity. Removal efficiency of microcystin by ozonation was investigated in laboratory according to contact time and ozone dose. Dissolved microcystin was increased by twice fold according to ozone contact time, but increased by fifth fold according to ozone dose. So, changing of ozone dose more affected microcystin release than changing of ozone contact time. Behavior of microcystin by ozonation was similar to that of DOC, and residual ozone concentration gave influence to removal ratio of microcystin. In conclusion, single ozone treatment wasn't effective on microcystin removal in case of water containing a lot of cells. Therefore, it's more effective to use ozonation process after the removal of cyanobacterial cells in advance.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1141-1148
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• 2008

One of the methods to increase the efficiency of an engine is to expand pressures obtained from combustions equal to the pressure of atmosphere as much as possible and then convert thermal energy into mechanical energy also as much as possible. In this research, the Diesel cycle was thermodynamically interpreted to evaluate the possibility of high efficiency by converting Diesel engines to the Atkinson cycle, and general cycle features were analyzed after comparing these two cycles. In the case of fuel air the Diesel-Atkinson cycle considering intake and exhaust similar to real cycles, the value of thermal efficiency and average effective pressure increased, though their values were smaller than those of standard air amount cycle, when expansion compression ratio increased. When normal Diesel engines of which compression stroke and expansion stroke are all the same, was converted to the Atkinson cycle by changing the time of intake value close, combustion pressure reduced due to reduced expansion compression ratio and intake air amount due to decreased effective cycle volume.

• Journal of Environmental Science International
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• v.13 no.11
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• pp.987-991
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• 2004

The purpose of this research is to evaluate the removal efficiencies of COD$\_$Cr/ and color for the dyeing wastewater by the different dosages of ferrous solution and H$_2$O$_2$ in Fenton process. In the case of H$_2$O$_2$ divided dosage for the Fenton's reagent 7:3 of H$_2$O$_2$ was more effective than 3:7 to remove COD$\_$Cr/ and color. The results showed that COD$\_$Cr/ was mainly removed by Fenton coagulation, where the ferric ions are formed in the initial step of Fenton reaction. On the other hand color was removed by Fenton oxidation rather than Fenton coagulation. The removal mechanism of COD$\_$Cr/ and color was mainly coagulation by ferrous ion, ferric ion and Fenton oxidation. The removal efficiencies were dependent on the ferric ion amount at the beginning of the reaction. However, the final removal efficiency of COD$\_$Cr/ and color was in the order of Fenton oxidation, ferric ion coagulation and ferrous ion coagulation. The reason of the highest removal efficiency by Fenton oxidation can be explained by the chain reactions with ferrous solution, ferric ion and hydrogen peroxide.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.4
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• pp.442-446
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• 2010

In this paper we propose an indexing method supporting the browsing scheme for effective image search on large photo database. The proposed method is based on M-tree, a representative indexing scheme on matrix space. While M-tree focuses on the searching efficiency by pruning, it did not consider browsing efficiency directly. This paper proposes node selection method, node splitting method and node splitting conditions for browsing efficiency. According to test results, node cohesion and clustering precision improved 1.5 and twice the original respectively and searching speed also increased twice the original speed.

• Journal of the Korean Ceramic Society
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• v.52 no.6
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• pp.479-482
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• 2015

The flue gas desulfurization (FGD) process is one of the most effective methods to reduce the amount of $SO_2$ gas (up to 90%) generated by the use of fossil fuel. Limestone is usually used as a desulfurizing agent in the wet-type FGD process; however, the limestone reserves of domestic mines have become exhausted. In this study, limestone sludge produced from the steel works process is used as a desulfurizing agent. Seven different types of additives are also used to improve the efficiency of the desulfurization process. As a result, alkaline additive is identified as the least effective additive, while certain types of organic acids show higher efficiency. It is also observed that the amount of FGD gypsum, which is a by-product of the FGD process, increases with the used of some of those additives.

• 한국태양에너지학회:학술대회논문집
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• 2012.03a
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• pp.480-487
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• 2012

The application of solar energy in residential building is general and natural in today. And application methods of solar thermal energy is divided in two kind of form, single evacuated tube and flat-plate form. Then in this study, the efficiency of single evacuated tube and flat-plate system is compared by total and effective area considering the time receiving the solar radiation between 24 hours and the specific time(10:00~15:00). As a result of the experiment, single evacuated tube and flat-plate collector's efficiency is varied by the quantity of solar radiation. And especially, the flat-plate system is more affected by outdoor temperature. Therefore the application of solar thermal system should be considered the solar radiation and outdoor temperature.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.6
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• pp.108-116
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• 2002

The diesel engine is one of the most effective transport options available in all sizes and covering a wide range of applications. But, many researchers developing the diesel engine are facing tough challenges in view of the increasingly lower emissions standards. Thus, this study will explore the possible fuel additive technology to further reduce the emissions from the IDI diesel engine. The purpose of this study is to investigate the effects of oxygenated fuels on the exhaust emissions and to attain a better trade-off relation between smoke and NOx in four cylinder diesel engine. Experiments were conducted with oxygenated fuels as an effective way to improve the combustion efficiency. Some of oxygenated fuel(Diglyme and DEE) were added to the conventional diesel fuel which had no an oxygen content. Also, EGR was adopted for reducing NOx without any strong adverse effects on other exhaust emissions. This study concluded that exhaust emissions in diesel engine could be reduced by adding the oxygenated fuels which had lower boiling point, and the combustion efficiency was also improved as the oxygen content in fuel increased.

• Environmental Engineering Research
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• v.22 no.2
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• pp.141-148
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• 2017

Globalization, industrialization, mining, and uncontrolled population growth have fostered a shortage of potable water. Therefore, it has become imperative to understand an effective and reasonable water purification technique. A renewed interest in electrocoagulation (EC) has been spurred by the search for reliable, cost-effective, water-treatment processes. This paper has elucidated a technical approach for getting rid of heavy metals and total suspended solids (TSS) from synthetic water using an aluminum electrode. The effect of operational parameters, such as current density, inter-electrode distance, operating time, and pH, were studied and evaluated for maximum efficiency. This study corroborates the correlation between current density and removal efficiency. Neutral pH and a low electrode gap have been found to aid the efficacy of the EC setup. The outcome indicates that a maximum TSS removal efficiency of 76.6% occurred at a current density of $5.3mA/cm^2$ during a contact time of 30 min. In the case of heavy metals remediation, 40 min of process time exhibited extremely reduced rates of 99%, 59.2%, and 82.1%, for Cu, Cr, and Zn, respectively. Moreover, kinetic study has also demonstrated that pollutants removal follows first-and second-order model with current density and EC time being dependent.