• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.4
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• pp.372-378
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• 2014

Noise in biomedical X-ray image degrades the quality so that it might causes to decrease the accuracy of diagnosis. Especially the noise reduction techniques is quite essential for low-dose biomedical X-ray images obtained from low radiation power in order to protect patients, because their noise level is usually high to well discriminate objects. This paper proposes an efficient method to remove the noise in low-dose X-ray images while preserving the edges with diverse resolutions. In the proposed method, a noisy image is at first decomposed into several images with different resolutions in pyramidal representation, then the stable map of edge confidence is obtained from each of analyzed image using a fuzzy logic-based edge detector. This map is used to adaptively determine the parameter for guided filters, which eliminate the noise while preserving edges in the corresponding image. The filtered images in the pyramid are extended and synthesized into a resulted image using interpolation technique. The superiority of proposed method compared to the median, bilateral, and guided filters has been experimentally shown in terms of noise removal and edge preserving properties.

• The Journal of the Korea Contents Association
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• v.20 no.8
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• pp.572-582
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• 2020

The purpose of this study was to investigate workplace bullying, job stress, organizational commitment, and turnover intention as well as determine influencing factors on the turnover intention of small and medium-sized hospital nurses. Participants included 140 nurses from six small and medium-sized hospitals with less than 300 beds in G-city and J-province. Data were analyzed using descriptive statistics, independent t-test, one-way analysis of variance, Pearson's correlation coefficient, and stepwise multiple regression, using the SPSS Win 21.0 program. The regression model was statistically significant (F=37.11, p<.001), and the explanatory power for turnover intention was 34.2%. The significant factors influencing turnover intention were organizational commitment (β=-.41, p<.001 and job stress (β=.25, p=.005). Human resources management is crucial for providing high quality healthcare service. The results of this study indicated that it is important to lower job stress and increase organizational commitment in order to reduce turnover intention among nurses of small and medium-sized hospitals. Based on these findings, customized programs for nurses in small and medium-sized hospitals need to be developed and implemented so as to lower their turnover intention and promote efficient management of healthcare human resources.

• Journal of Food Hygiene and Safety
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• v.31 no.2
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• pp.119-125
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• 2016

Antioxidative components and activities of the extracts from Pleurotus ostreatus extracted at different ethanol concentration were analyzed and their correlation were investigated. Ergothioneine, total phenolic compounds, and flavonoid contents of the extracts from P. ostreatus extracted with hot water (0% ethanol) were the highest ($2.98{\pm}0.05$, $9.51{\pm}0.45$, and $2.83{\pm}0.03mg/g$, respectively) and the contents were decreased according to increase of ethanol concentration for extraction. DPPH and ABTS radical scavenging activities of the extracts from P. ostreatus extracted with hot water were the highest ($80.41{\pm}0.56$ and $91.47{\pm}0.11%$, respectively). FRAP value also showed the highest reducing power by $8.86{\pm}0.33\;FeSO_4\;eq$. mM in hot water extracts. Positive correlations were found between ergothioneine contents and antioxidative active components and antioxidant activity of the extracts from P. ostreatus. Results indicate that hot water extraction was most efficient for the extracts with high antioxidative activities from P. ostreatus.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.12 no.4
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• pp.315-334
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• 2014

Wolsong Low- and Intermediate-level radioactive waste (LILW) disposal center has two different types of disposal facilities and interacts with the neighboring Wolsong nuclear power plant. These situations impose a high level of complexity which requires in-depth understanding of phenomena in the safety assessment of the disposal facility. In this context, multidimensional radionuclide transport model and hydraulic performance assessment model should be developed to identify more realistic performance of the complex system and reduce unnecessary conservatism in the conventional performance assessment models developed for the $1^{st}$ stage underground disposal. In addition, the advanced performance assessment model is required to calculate many cases to treat uncertainties or study parameter importance. To fulfill the requirements, this study introduces the development of two-dimensional integrated near-field performance assessment model combining near-field hydraulic performance assessment model and radionuclide transport model for the $2^{nd}$ stage near-surface disposal. The hydraulic and radionuclide transport behaviors were evaluated by PORFLOW and GoldSim. GoldSim radionuclide transport model was verified through benchmark calculations with PORFLOW radionuclide transport model. GoldSim model was shown to be computationally efficient and provided the better understanding of the radionuclide transport behavior than conventional model.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.7
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• pp.743-750
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• 2008

In water treatment plant the Dissolved Ozone Flotation(DOF) System may be employed because this system has various abilities, such that it can remove SS using microbubbles, and it can exert strong oxidation power in removing taste and odor, color, and microbial agents. In order to investigate effectiveness of the DOF system in water treatment, removal characteristics of various water quality parameters were observed depending on the different levels of ozone concentrations. Removal efficiencies of water quality parameters in DOF system were compared with those in DAF(Dissolved Air Flotation) system and in CGS(Conventional Gravity Settling) system. Optimum ozone dose obtained in the pilot experiments was 2.7 mg/L. With increasing ozone dose higher than 2.7 mg/L, removal rates of turbidity, KMnO$_4$ consumption, UV$_{254}$ absorbance, and TOC were reversely lowered. High concentration of ozone dissociate organic matter in water, so that increasing dissolved organic level in effluent. Removal rates of water quality parameters at optimum ozone dose were obtained, such that removal rates of turbidity, KMnO$_4$ consumption, TOC, and UV$_{254}$ asorbance were 88.9%, 62.9%, 47%, and 77.3% respectively. Removal rate of THMFP was 51.6%. For all the parameters listed above, the DOF system was more effective than the DAF system or the CGS system. It is found that the DOF system may be used in advanced water treatment not only because the DOF system is more efficient in removing water quality parameters than the existing systems, but because the DOF system is also required smaller area than the CGS system for the treatment plant.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.673-680
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• 2017

sump pump is a system that draws in water that is stored in a dam or reservoir. They are used to pump large amounts of water for cooling systems in large power plants, such as thermal and nuclear plants. However, if the flow and sump pump ratio are small, the flow rate increases around the inlet port. This causes a turbulent vortex or swirl flows. The turbulent flow reduces the performance and can cause failure. Various methods have been devised to solve the problem, but a correct solution has not been found for low water level. The most efficient solution is to install an anti-vortex device (AVD) or increase the length of the sump inlet, which makes the flow uniform. This paper presents a computational fluid dynamics (CFD) analysis of the flow characteristics in a sump pump for different sump inlet lengths and AVD types. Modeling was performed in three stages based on the pump intake, sump, and pump. For accurate analysis, the grid was made denser in the intake part, and the grid for the sump pump and AVD were also dense. 1.2-1.5 million grid elements were generated using ANSYS ICEM-CFD 14.5 with a mixture of tetra and prism elements. The analysis was done using the SST turbulence model of ANSYS CFX14.5, a commercial CFD program. The conditions were as follows: H.W.L 6.0 m, L.W.L 3.5, Qmax 4.000 kg/s, Qavg 3.500 kg/s Qmin 2.500 kg/s. The results of analysis by the vertex angle and velocity distribution are as follows. A sump pump with an Ext E-type AVD was accepted at a high water level. However, further studies are needed for a low water level using the Ext E-type AVD as a base.

• Journal of Navigation and Port Research
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• v.44 no.4
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• pp.338-346
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• 2020

In this study, we first measured the Malmquist productivity index by DEA among the Korean ocean carriers. Second, it was intended to present measures to improve productivity by identifying the influence and discriminating power between productivity and the major financial ratios (profitability, financial stability, liquidity, efficiency and value-added productivity). Compared to 2017, there are 11 more shipping carriers with decline in productivity (MPI) than those with an increase in 2018. The increase in productivity is attributed to an increase in the Technology Change Index (TCI) affected by the external environment. There is strong significant correlation between the productivity (MPI) and the management efficiency (CRS). Additionally, the TECI (TECHI) index of the technological efficiency changes from internal factors of the shipping carrier is significantly higher than that of the efficient shipping carrier. This is because of the differences in scale efficiency. The ratio of charter cost/sales is also lower than that of the carriers with high productivity (0.17) and with low productivity (0.21). With 7% of the shipping carrier with MPI>1, only 1% of MPI <1 is found to have a significant impact on its productivity.

• Journal of KIISE:Computing Practices and Letters
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• v.11 no.1
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• pp.36-49
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• 2005

Recently, many researchers have given high attention to the semantic web services based on the semantic web technology While existing web services use the XML-based web service description language, WSDL, semantic web services are utilizing web service description languages such as DAML-S in ontology languages. The researchers of semantic web services are generally focused on web service discovery, web service invocation, web service selection and composition, and web service execution monitoring. Especially, the semantic web service discovery as the basis to accomplish the ultimate semantic web service environment has some different properties from previous information discovery areas. Hence, it is necessary to develop the storage system and discovery mechanism appropriate to the semantic well description languages. Even though some related systems have been developed, they are not appropriate for the embedded system environment, such as intelligent robotics, in which there are some limitations on memory disk space, and computing power In this regard, we in the embedded system environment have developed the document management system which efficiently manages the web service documents described by DAML-S for the purpose of the semantic web service discovery, In addition, we address the distinguishing characteristics of the system developed in this paper, compared with the related researches.

• International Journal of Highway Engineering
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• v.17 no.3
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• pp.49-58
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• 2015

PURPOSES : The use of environmentally friendly construction methods has been recently encouraged to reduce fuel consumption and the effects of global warming. For this purpose, the roller compacted concrete pavement (RCCP) construction method has been developed. RCCP is more environmentally friendly and economically efficient than general concrete by reducing the amount of CO2 generated through the application of a smaller amount of cement. RCCP has a number of advantages such as an easy construction method, low cost, high structural hydration performance, and aggregate interlocking. However, mix design standards and construction guidelines of RCCP are required for domestic application. In addition, a study on aggregate selection, which has an effect on the characteristics of RCCP, is necessary owing to a limited number of researches. Thus, the aggregate effect on the performance of RCCP in securing the required strength and workability was evaluated in consideration of domestic construction. METHODS : Sand and coarse aggregates of both 19mm and 13mm in maximum size were used in this study. Four types of aggregate gradations (s/a = 30%, 58%, and 70% for the sand and coarse aggregate of 19mm in maximum size, and s/a = 50% for a combination of the three types of aggregates) were set up to investigate the effects of the PCA band on the RCC characteristics. The conditions of s/a = 30% and 70% were evaluated to check the gradation effect outside of the recommended band. The conditions of s/a = 58% and 50% were used because they are the optimum combination of the two and three types of aggregates, respectively. RCCP gradation band was suggested gradation with a proper construction method of RCCP by synthetically comparing and analyzing the correlation of optimum water content, maximum dry density, and strength of requirements through its consistency and compaction test. RESULTS : The lower and upper limit lines are insufficient to secure a relatively strong development and workability compared to an aggregate gradation in the RCCP gradation band region. On the other hand, the line in the RCCP gradation band and the 0.45 power curve in the RCCP gradation band region were satisfactory, ensuring the required strength and workability. CONCLUSIONS : The suitable aggregate gradation on RCCP process should meet the RCCP gradation band area; however, fine particles passing through a #60 sieve do not need to be within the recommended gradation band because the influence of this region on such fine particles is small.

• Membrane Journal
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• v.30 no.3
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• pp.173-180
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• 2020

As the demand for fossil fuels continues to increase worldwide, carbon dioxide (CO₂) concentration in the air has increased over the centuries. The way to reduce CO₂ emissions to the atmosphere, carbon capture and sequestration (CCS) technology have been developed that can be applied to power plants and factories, which are primary emission sources. According to the climate change mitigation policy, direct air capture (DAC) in air, referred to as "negative emission" technology, has a low CO₂ concentration of 0.04%, so it is focused on adsorbent research, unlike conventional CCS technology. In the DAC field, chemical adsorbents using CO₂ absorption, solid absorbents, amine-functionalized materials, and ion exchange resins have been studied. Since the absorbent-based technology requires a high-temperature heat treatment process according to the absorbent regeneration, the membrane-based CO₂ capture system has a great potential Membrane-based system is also expected for indoor CO₂ ventilation systems and immediate CO₂ supply to smart farming systems. CO₂ capture efficiency should be improved through efficient process design and material performance improvement.