• Journal of Environmental Impact Assessment
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• v.26 no.6
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• pp.418-430
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• 2017

The quality of surface water is a very important issue to use various demands like as drinking water, industrial, agricultural and recreational usages. There has been an increasing demand for monitoring water quality of many rivers by regular measurements of various water quality variables. However precise and effective monitoring is not enough, if the acquired dataset is not analyzed thoroughly. Therefore, the aim of this study was to estimate differences of seasonal and regional water quality using multivariate data analysis for each investing tributaries in Han River. Statistical analysis was applied to the data concerning 11 mainly parameters (flow, water temperature, pH, EC, DO, BOD, COD, SS, TN, TP and TOC) for the time period 2012~2016 from 12 sampling sites. The seasonal water quality variations showed that each of BOD, TN, TP and TOC average concentration in spring and winter was higher than that of summer and fall, respectively. In summer each flow rate and average concentration of SS was higher than any other seasons, respectively. The correlation analysis were explained that EC had a strong relationship with BOD (r=0.857), COD (r=0.854), TN (r=0.899) and TOC (r=0.910). According to principal component analysis, five principal components (Eigenvalue > 1) are controlled 98.0% of variations in water quality. The first component included TP, DO, pH. The second component included EC, TN. The third component included SS. The fourth component included flow. The last component included Temp. Cluster analysis classified that spring is similar to fall and winter with water quality parameters. AnyA, WangsA, JungrA and TancA were identified as affected by organic pollution. Cluster analysis derived seasonal differences with investigating sites and better explained the principal component analysis results.

• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.111-120
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• 2023

The nucleation mechanism was studied using a calcium ion selective electrode (Ca ISE) to observe the formation of CaCO₃, a representative mineral in the CO2 cycle, and to analyze the effect of the Mg/Ca-ratio and temperature on the formation of pre-nucleation cluster (PNC) and CaCO₃. As a result of the experiment, a small amount of crystal was formed. Energy dispersive X-ray spectroscopy (EDS) was used for surface element analysis, and a field emission scanning-electron microscope (FE-SEM) was used for the morphology analysis of synthesized carbonates. These results showed that various shapes of crystalline CaCO₃ (calcite, aragonite, etc.) were observed for each Mg/Ca ratio and temperature. In addition, the calibration plot obtained from Ca ISE showed information on the formation process of CaCO₃. Our results showed that as magnesium ions interfered with the binding of calcium and carbonate ions and delayed the aggregation between PNCs, the nucleation and formation of CaCO₃ were delayed. On the other hand, the temperature showed an opposite trend as compared to the effect of magnesium under our experimental conditions, indicating that temperature accelerated the formation of CaCO₃. Furthermore, the morphology of CaCO₃ clearly changed according to the Mg/Ca ratio and temperature, and it was confirmed that the two factors are very important for CaCO₃ formation in that they could affect the overall process.

• Journal of Microbiology and Biotechnology
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• v.17 no.8
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• pp.1330-1337
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• 2007

To better understand the gene expression of the cold-adapted polar diatom, we conducted a survey of the Chaetoceros neogracile transcriptome by cDNA sequencing and expression of interested cDNAs from the Antarctic diatom. A non-normalized cDNA library was constructed from the C. neogracile, and a total of 2,500 cDNAs were sequenced to generate 1,881 high-quality expressed sequence tags (ESTs) (accession numbers EL620615-EL622495). Based on their clustering, we identified 154 unique clusters comprising 342 ESTs. The remaining 1,540 ESTs did not cluster. The number of unique genes identified in the data set is thus estimated to be 1,694. Taking advantage of various tools and databases, putative functions were assigned to 939 (55.4%) of these genes. Of the remaining 540 (31.9%) unknown sequences, 215 (12.7%) appeared to be C. neogracile-specific since they lacked any significant sequence similarity to any sequence available in the public databases. C. neogracile consisted of a relatively high percentage of genes involved in metabolism, genetic information processing, cellular processes, defense or stress resistance, photosynthesis, structure, and signal transduction. From the ESTs, the expression of these putative C. neogracile genes was investigated: fucoxanthin chlorophyll (chl) a,c-binding protein (FCP), ascorbate peroxidase (ASP), and heat-shock protein 90 (HSP90). The abundance of ASP and HSP90 changed substantially in response to different culture conditions, indicating the possible regulation of these genes in C. neogracile.

• Korea Journal of Hospital Management
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• v.17 no.2
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• pp.21-33
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• 2012

Purpose : This study aims to suggest application of patients DB to hospital marketing by performing market segmentation and selecting target market. Consequently help to establish suited strategy of marketing. Method : 14,072 patients hospitalized in a University Medical Center were recruited into this study. In order to classify the customer groups, cluster analysis was used with RFM(Recency, Frequency, Monetary) model, and 1-way ANOVA verified the differences among groups. And then, sociodemographical status, healthcare utilization and diagnosis(ICD-10) of each group were compared to draw a marketing strategy. Results : Four groups were classified through clustering analysis, and'high use and high profit' and'low use and high profit' groups were selected as a target market. The features of target market were as follows, the female proportion was high; used a private room; hospitalized through the emergency room; had operation; length of stay was long; had many comorbidity and cooperative treatment. There was difference in each feature of target market: as for the'high use and high profit' group, many patients were diagnosed with 'certain infectious and parasitic diseases'; and as for the'low use and high profit'group, the proportion of patients who purchased'industrial accident compensation insurance'and'auto insurance'was relatively high; many patients were diagnosed with'Injury, poisoning and certain other consequences of external causes'. Conclusion : It is needed to establish'positioning' strategy by monitoring and communicating with'high use and high profit' group. And for the case of'low use and high profit' group, it is necessary to make a follow-up management and lead them to have a medical check-up.

• Composites Research
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• v.26 no.4
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• pp.218-222
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• 2013

This study demonstrated that a slag, an industrial solid waste, can be used as a structural reinforcement. The mechanical properties(tensile strength and Elastic modulus) of slag reinforced composite(SRC) was investigated as functions of slag particle size (8~12 ${\mu}m$ and 12~16 ${\mu}m$) and volume fraction (0-40 vol.%). In order to investigate the interface and a degree of particle dispersion which have an effect on mechanical properties, optical microscopic images were taken. The results of tensile tests showed that the tensile strength decreased with an increase in slag volume fraction and particle size. The elastic modulus increased with an increase in slag volume fraction and particle size except for 30 vol.% SRC. The tensile strength decreased with an increase in slag particle size. The microscopic picture showed SRC has fine degree of particle dispersion at low slag volume fraction. SRC has a good interface at every volume fraction. However particle cluster was incorporated with an increase in slag volume fraction.

• The Journal of Society for e-Business Studies
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• v.25 no.3
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• pp.15-40
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• 2020

Due to the explosive growth of mobile application services, categorizing mobile application services is in need in practice from both customers' and developers' perspectives. Despite the fact, however, there have been limited studies regarding systematic categorization of mobile application services. In response, this study proposed a method for categorizing mobile application services, and suggested a service taxonomy based on the network clustering results. Total of 1,607 mobile healthcare services are collected through the Google Play store. The network analysis is conducted based on the similarity of descriptions in each application service. Modularity detection analysis is conducted to detects communities in the network, and service taxonomy is derived based on each cluster. This study is expected to provide a systematic approach to the service categorization, which is helpful to both customers who want to navigate mobile application service in a systematic manner and developers who desire to analyze the trend of mobile application services.

• Environmental Engineering Research
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• v.23 no.1
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• pp.28-35
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• 2018

$17{\alpha}-ethinylestradiol$ (EE2), a synthetic estrogen which interfere the endocrine and reproductive function in living organisms, has been found extensively to be deposited into municipal wastewater treatment plants and the environment via human excretion. EE2 has long been known to be efficiently cometabolized by ammonia-oxidizing bacteria (AOB) during ammonia ($NH_3$) oxidation. Current study aims to investigate the effect of culture history on the biotransformation of EE2 by nitrifying sludge which was enriched under different ammonia loading rates in continuous flow reactors. Result showed that past growth condition largely affected not only the metabolic rate of $NH_3$ oxidation but also EE2 cometabolism. Sludge previously acclimated with higher $NH_3$ loads as well as sludge dominated with AOB belong to high growth cluster (Nitrosomonas europaea-Nitrosococcus mobilis) showed higher rate of EE2 biotransformation than those one being acclimated with lower $NH_3$ loads because of its ability to provide more reducing power from $NH_3$ oxidation. Moreover, the correlation between the degradation rates of $NH_3$ and EE2 was higher in sludge being acclimated with higher load of $NH_3$ in comparison with other sludge. Implication of the findings emphasized the role of volumetric $NH_3$ loading rate in determining EE2 removal in wastewater treatment system.

• Korean Business Review
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• v.21 no.2
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• pp.79-97
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• 2008

Between different organization, they creat competitiveness from the result of their own manufacturing and sales activity especially the manufacturing companies. This paper will focus on the spot location strategy of korea company which have oversea business and find out the relationship between the spot location strategy and the resources or competitive ability of this kind of companies. Each company has their own way to realize their overseas business expansion and creat their competitiveness in their international business. At the same time, they also have their own way to share their resources and their competitive ability. All this 3 kinds of strategies are important and the combination of them is more important for companies that have overseas business. To examine the relationship between the spot location, the resources and the competitive ability strategies, this paper developed two hypotheses and tested them. To test the hypotheses, this paper conducted a mail survey to operations managers of overseas companies in Korea and collected 102 usable responses. To simplify the responses, this paper used cluster analysis and found 3groups of spot location strategy, 2 groups of resources strategy and 2 groups of competitive abilities strategy. This paper also investigated interdependence and performance differences between these groups. From the analyses, this paper found the following results: It is important for a overseas company to make their spot location strategy to be fit for their resources strategy and competitive abilities strategy and a perfect spot location strategy can make the company gain a advantage of high level in most of time.

• Journal of the Korean Ceramic Society
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• v.42 no.9 s.280
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• pp.602-606
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• 2005

[ $LiCoO_{2}$ ] is the most common cathode electrode materials in Lithium-ion batteries. $LiCo_{0.97}Mg_{0.03}O_2$ was synthesized by the solid-state reaction method. We investigated crystal structures, electrical conductivities and electrochemical properties. The crystal structure of $LiCo_{0.97}Mg_{0.03}O_2$ was analyzed by X-ray powder diffraction and Rietveld refinement. The material showed a single phase of a layered structure with the space group R-3m. The lattice parameter(a, c) of $LiCo_{0.97}Mg_{0.03}O_2$ was larger than that of $LiCoO_2$. The electrical conductivity of sintered samples was measured by the Van der Pauw method. The electrical conductivities of $LiCoO_2$ and $LiCo_{0.97}Mg_{0.03}O_2$ were $2.11{\times}10^{-4}\;S/cm$ and $2.41{\times}10^{-1}\;S/cm$ at room temperature, respectively. On the basis of the Hall effect analysis, the increase in electrical conductivities of $LiCo_{0.97}Mg_{0.03}O_2$ is believed due to the increased carrier concentrations, while the carrier mobility was almost invariant. The electrochemical performance was investigated by coin cell test. $LiCo_{0.97}Mg_{0.03}O_2$ showed improved cycling performance as compared with $LiCoO_2$.

• Journal of the Economic Geographical Society of Korea
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• v.14 no.1
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• pp.71-85
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• 2011

Many of the old industrial cities in advanced economies have experienced deindustrialization since the 1960s. While some of them have been transforming their economic structures with new economies, such as arts and cultural industries, others have been seriously suffering from economic and social problems. Brooklyn Borough of New York City is one of the best examples which have gone trough rapid de-industrialization; but have been reasonably successful in recovering its economy with arts and cultural industries. This paper introduces the process of developing creative industry clusters, articulates major actors, and find out the governance of the clusters, using three Brooklyn's arts clusters, such as DUMBO, BAM and Williamsburg. Based on the case studies, the paper draws theoretical and policy implications applicable to the Korean circumstance.