• Journal of Digital Contents Society
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• v.19 no.9
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• pp.1769-1778
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• 2018

As the value of using Big Data is increasing, various researches are being carried out utilizing big data analysis technology in the field of education as well as corporations. In this paper, we propose a method to predict learning achievement using big data cluster analysis. In the proposed method, students in Korea Children and Youth Panel Survey(KCYPS) are classified into groups with similar learning habits using the Kmeans algorithm based on the learning habits of students of the first year at middle school, and group features are extracted. Next, using the extracted features of groups, the first grade students at the middle school in the test group were classified into groups having similar learning habits using the cosine similarity, and then the neighbors were selected and the learning achievement was predicted. The method proposed in this paper has proved that the learning habits at middle school are closely related to at the university, and they make it possible to predict the learning achievement at high school and the satisfaction with university and major.

• Journal of The Korean Astronomical Society
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• v.41 no.5
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• pp.121-137
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• 2008

We present optical and near-infrared imaging and long-slit spectroscopy for the blue compact dwarf galaxy (BCD) Mrk 49 in the Virgo Cluster. The surface brightness distribution analysis shows that Mrk 49 consists of an off-centered blue bright compact core of r = 10" and a red faint outer exponential envelope. The $H_{\alpha}$ image and color difference suggest that these two components have different stellar populations: a high surface brightness population of massive young stars and an underlying low surface brightness population of older stars. The redder near-infrared colors of the inner most region suggest that the near-infrared flux of Mrk 49 originates from evolved massive stars associated with the current star-forming activity. The total apparent magnitude is $B_T\;=\;14.32$ mag and the mean effective surface brightness is ${\mu}_{eff}(B)\;=\;21.56$ mag $arcsec^{-2}$. Long-slit spectroscopy shows that Mrk 49 rotates apparently as a solid body within r = 10" in a plane at position angle 55 degrees with an amplitude of about $20\;km\;sec^{-1}$. The measured radial velocity of Mrk 49 was derived as $1,535\;km\;sec^{-1}$; and the total mass of stars and gases is in the range of 3 to $6\;{\times}\;10^9\;M_{\odot}$. The mass-to-light ratios for the central region of Mrk 49 in I and B band are estimated 1.0 and 0.5, respectively. The upper limit of the dark matter to visible matter ratio seems to be < 5. The oxygen abundance is $12\;+\;\log(O/H)\;=\;8.21\;{\pm}\; 0.1$ which is about one quarter of the solar value while the relative helium abundance appears to be similar to that of the sun.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.33.1-33.1
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• 2018

The differential rotational properties of early-type galaxies (ETGs) revealed by integral field spectroscopy surveys is arguably one of the most exciting findings in the galaxy evolution study during the past decade. Numerical studies have shown that galaxy mergers under various configurations can reproduce the observed distribution of ETG spin. However, we suggest an alternative scenario for the spin evolution of a large fraction of ETGs. Using the Horizon-AGN simulation, we follow the spin evolution of 10037 color-selected ETGs more massive than 1010 Msun that are divided into four groups: cluster centrals (3%), cluster satellites (33%), group centrals(5%), and field ETGs (59%). We find a strong mass dependence of the slow rotator fraction, fSR, and the mean spin of massive ETGs. Although the environmental dependence is not clear in the fSR, it is visible in the mean value of the spin parameter. The environmental dependence is driven by the satellite ETGs whose spin gradually decreases as their environment becomes denser. Galaxy mergers appear to be the main cause of total spin changes in 94% of central ETGs of halos with Mvir > 1012.5 Msun, but only 22% of satellite and field ETGs. We find that non-merger induced tidal perturbations better correlate with the galaxy spin-down in satellite ETGs than mergers. Given that the majority of ETGs are not central in dense environments, we conclude that non-merger tidal perturbation effects played a key role in the spin evolution of ETGs observed in the local (z < 1) universe.

• Journal of Korean Society of Forest Science
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• v.104 no.3
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• pp.368-374
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• 2015

On the basis of vegetation data by point quarter sampling method, the natural forest of Jirisan(Mt.) was classified into eight forest types by cluster analysis. They were Quercus mogolica forest type, Fraxinus mandshurica - Betula costata forest type, Mixed mesophytic forest type, Abies koreana forest type, Carpinus laxiflora forest type, Quercus serrata forest type, Pinus densiflora forest type, and Quercus variabilis forest type. Then, succession index was estimated for each forest type so as to evaluate succession process comparatively among forest types. The results showed that Carpinus laxiflora forest type had highest succession index of 219.7, followed by Mixed mesophytic forest type with little difference of the index of 218.3. Pinus densiflora forest type had lowest index. Succession indices were hardly correlated with species diversity indices of forest types. We presumed that the higher value of succession index a forest type had, the closer toward the climax forest. However, the estimated index was not supposed to be absolute level of successional stage, but it could play a role of comparative assessment in the position of the seral stage among forest types.

• Journal of Korea Multimedia Society
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• v.3 no.4
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• pp.339-346
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• 2000

Medical image is analyzed to get an anatomical information for diagnostics. Segmentation must be preceded to recognize and determine the lesion more accurately. In this paper, we propose automatic segmentation algorithm for MR brain images using T1-weighted, T2-weighted and PD images complementarily. The proposed segmentation algorithm is first, extracts cerebrum images from 3 input images using cerebrum mask which is made from PD image. And next, find 3D clusters corresponded to cerebrum tissues using scale filtering and 3D clustering in 3D space which is consisted of T1, T2, and PD axis. Cerebrum images are segmented using FCM algorithm with its initial centroid as the 3D cluster's centroid. The proposed algorithm improved segmentation results using accurate cluster centroid as initial value of FCM algorithm and also can get better segmentation results using multi spectral analysis than single spectral analysis.

• Journal of Microbiology and Biotechnology
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• v.16 no.2
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• pp.193-199
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• 2006

Halotolerant spore-forming Gram-positive bacteria were isolated from the root, rhizosphere, and non-rhizosphere soil of Blutaparon portulacoides. The different isolates were characterized genetically using an amplified ribosomal DNA restriction analysis (ARDRA), and phenotypically based on their colonial morphology, physiology, and nutritional requirements. Three different 16S rRNA gene-based genotypes were observed at a 100% similarity using the enzymes HinfI, MspI, and RsaI, and the phenotypic results also followed the ARDRA groupings. Selected strains, representing the different ARDRA groups, were analyzed by 16S rDNA sequencing, and members of the genera Halobaeillus, Virgibacillus, and Oceanobacillus were found. Two isolates showed low 16S rDNA sequence similarities with the closest related species of Halobacillus, indicating the presence of new species among the isolates. The majority of the strains isolated in this study seemed to belong to the species O. iheyensis and were compared using an AP-PCR to determine whether they had a clonal origin or not. Different patterns allowed the grouping of the strains according to Pearson's coefficient, and the resulting dendrogram revealed the formation of two main clusters, denoted as A and B. All the strains isolated from the soil were grouped into cluster A, whereas cluster B was exclusively composed of the strains associated with the B. portulacoides roots. This is the first report on the isolation and characterization of halotolerant spore-forming Gram-positive bacteria that coexist with B. portulacoides. As such, these new strains may be a potential source for the discovery of bioactive compounds with industrial value.

• Journal of Korean Society of Rural Planning
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• v.21 no.1
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• pp.129-141
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• 2015

This study classifies the types of spatio-functional differentiation in Korean island areas and analyses typical characters and suggests the development directions by each type. Eup/Myeon-level island areas are classified as six types by the factor analysis and the cluster analysis. First type is the traditional rural center. This type puts emphasis on maintaining phase as the central space and has to maximize development potential of the whole of settlement zone. Second type is the specialized region in manufacturing industry and the qualitative mutual growth of regional industries is able to be suggested. Third type is the specialized region in the neighborhood service provision. This type needs to devise the plan for utilizing potential customers actively and developing into the region specialized in tourism industry. Fourth type is the specialized region in tourism-support service functions. This type has to promote differentiated policies for maintaining amenity infra or value of countryside capital and preservation and utilization of resources by regional features. Fifth type is the fishing industry-dominated region. This type has to promote sustainable fishery development through the policy reflecting regional features and condition. Finally, sixth type is the sluggish region dominated with the traditional agriculture and fishery. This type is needed to aim at developing into the new food production base having the advantage of clean environment by strengthening support in specialized agro-fishery products. The existing researches on spatio-functional differentiation were mostly discussed with respect to land development, but this study highlights the difference in deal with the island areas distinguished from the condition of industry.

• Journal of Preventive Medicine and Public Health
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• v.42 no.2
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• pp.135-142
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• 2009

Objectives : An appropriate sampling strategy for estimating an epidemiologic volume of diabetes has been evaluated through a simulation. Methods : We analyzed about 250 million medical insurance claims data submitted to the Health Insurance Review & Assessment Service with diabetes as principal or subsequent diagnoses, more than or equal to once per year, in 2003. The database was re-constructed to a 'patient-hospital profile' that had 3,676,164 cases, and then to a 'patient profile' that consisted of 2,412,082 observations. The patient profile data was then used to test the validity of a proposed sampling frame and methods of sampling to develop diabetic-related epidemiologic indices. Results : Simulation study showed that a use of a stratified two-stage cluster sampling design with a total sample size of 4,000 will provide an estimate of 57.04%(95% prediction range, 49.83 - 64.24%) for a treatment prescription rate of diabetes. The proposed sampling design consists, at first, stratifying the area of the nation into "metropolitan/city/county" and the types of hospital into "tertiary/secondary/primary/clinic" with a proportion of 5:10:10:75. Hospitals were then randomly selected within the strata as a primary sampling unit, followed by a random selection of patients within the hospitals as a secondly sampling unit. The difference between the estimate and the parameter value was projected to be less than 0.3%. Conclusions : The sampling scheme proposed will be applied to a subsequent nationwide field survey not only for estimating the epidemiologic volume of diabetes but also for assessing the present status of nationwide diabetes control.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.5
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• pp.385-392
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• 2002

Collaborative filtering method for personalization can suggest new items and information which a user hasn t expected. But there are some problems. Not only the steps for calculating similarity value between each user is complex but also it doesn t reflect user s interest dynamically when a user input a query. In this paper, classifying users by their interest makes calculating similarity simple. We propose the a1gorithm for readjusting user s interest dynamically using the profile and Bayesian learning. When a user input a keyword searching for a item, his new interest is readjusted. And the user s profile that consists of used key words and the presence frequency of key words is designed and used to reflect the recent interest of users. Our methods of adjusting user s interest using the profile and Bayesian learning can improve the real satisfaction of users through the experiment with data set, collected in University s library. It recommends a user items which he would be interested in.

• Journal of Korea Game Society
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• v.18 no.1
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• pp.105-114
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• 2018

Various data analysis methods used for customer type analysis are very important for game companies to understand their type and characteristics in an attempt to plan customized content for our customers and to provide more convenient services. In this paper, we propose a k-mode cluster analysis algorithm that uses information uncertainty by extending information entropy to reduce information loss. Therefore, the measurement of the similarity of attributes is considered in two aspects. One is to measure the uncertainty between each attribute on the center of each partition and the other is to measure the uncertainty about the probability distribution of the uncertainty of each property. In particular, the uncertainty in attributes is taken into account in the non-probabilistic and probabilistic scales because the entropy of the attribute is transformed into probabilistic information to measure the uncertainty. The accuracy of the algorithm is observable to the result of cluster analysis based on the optimal initial value through extensive performance analysis and various indexes.