• The Korean Journal of Applied Statistics
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• v.22 no.2
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• pp.415-424
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• 2009

As one of the unsupervised learning neural network methods, self-organizing maps(SOM) are applied to various fields. It reduces the dimension of multidimensional data by representing observations on the low dimensional manifold. On the other hand, the minimal spanning tree(MST) of a graph that achieves the most economic subset of edges connecting all components by a single open loop. In this study, we apply the MST technique to SOM with subnodes. We propose SOM's with embedded MST and a distance measure for optimum choice of the size and shape of the map. We demonstrate the method with Fisher's Iris data and a real gene expression data. Simulated data sets are also analyzed to check the validity of the proposed method.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.24 no.4
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• pp.248-254
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• 1991

The demersal fishes of Asan Bay were collected by an otter trawl in August 1990 to determine optimum sample size for the analysis of community structure. A total of 17 species comprising 957 individuals and 21,840 grams in biomass was collected. Predominant species were Cynoglossus joyneri, Thrissa koreana, Hexagrammos otakii and Johnius belengerii. Coefficients of variation for fish numbers in ten replicate tows ranged from 2.2 to $385.1\%$ for four abundant species and from 52.2 to $162.0\%$ when all species were considered. The cumulative number of species increased rapidly until 4 hauls, and less than 1 species per haul in average was added thereafter. The cumulative diversity index reached nearly an asymptote value when three of samples were combined. Variance in the number of individuals diminished as the sample size increased. The ratio of variance to mean numbers (dispersion index) was not significantly different from the unity when first 4-haul samples were combined. Four of 20-minute trawl haul are proposed to be a proper sampling size for the unbiased estimation of abundance in the study area.

• Korean Journal of Environment and Ecology
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• v.21 no.6
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• pp.506-514
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• 2007

Temporal and spatial distribution of fish community were investigated from September 2006 to April 2007 targeting the lagoon Youngrang, Korea. A total of 32 species belonging to 16 families were collected during the period, among which the species of primary freshwater fish accounted for 11 (34.38%), the species of peripheral freshwater fish for 18 (56.25%), and that of marine fish for 3 (9.38%) in collected fish community. As a result of taking a look at the transitional aspects of community by each surveyed station and period, it was found that when the 'Breaking-sandbar' occurred, there came a change in the composition ratio of the fish species according to their ecological characteristics. In addition, compared with the data obtained in the past with respect to the ichthyofauna of the lagoon Youngrang, it was found that the ratio of the primary freshwater species gradually decreased, while the peripheral freshwater and seawater species gradually increased according to the indraft of seawater. Thus, it was concluded that fish community in the lagoon seemed to go under transition in its spatio-temporal characteristics depending on the 'Breaking- sandbar.'

• Journal of Digital Convergence
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• v.12 no.8
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• pp.397-410
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• 2014

This study sought to identify types of health behavior clusters among Korean adults and their related factors. A secondary analysis of 1,441 subjects, aged 19 to 64, in the 2009 Korean National Health and Nutrition Examination Survey (KNHANES IV-3) was conducted. A cluster analysis was used to identify types of clusters related to physical activity, smoking, and alcohol drinking. A complex samples chi square test and multivariate logistic regression were performed to analyze the associations between types of health behavior clusters and sample's characteristics using SPSS WIN 21. Five clusters were identified: health promotion, smoking, alcohol drinking, passive attitude, and risky behavior. The passive attitude cluster had the most subjects, with 47.7% of subjects as members. Socio-demographic factors, hypertension, and depressive symptoms were associated with membership in the alcohol drinking, smoking, passive attitude, or risky behavior cluster rather than the health promotion cluster. The findings of this study suggest that integrated health promotion programs incorporating multiple strategies need to be investigated. In addition, further studies should explore psychosocial factors that affect health behavior clusters, such as stress, self-efficacy, social support, and social networks.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.1
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• pp.203-215
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• 2015

The study aims to identify the degree and types of spatial recessions in Si/Gun and Eup/Myun units within Chungcheong region in South Korea to contribute to the efforts being made to diagnose the rural recession and the potentials. To this end, we analyzed 27 Sis and Guns to identify the degree of recession and potentials of rural areas in Chungcheong region. We also carried out the diagnosis and K-Means Clustering on 274 Eups and Myuns, smaller administrative units, to figure out the types and characteristics of the rural recessions. In case of the analysis targeting the Sis and Guns, a relatively high degree of rural recession was found in Cheongyang, Seocheon and Taean for Chungcheongnam-do, and in Danyang and Goisan, as well as in Boeun, Okcheon and Youngdong - which are collectively called as 'Southern 3 Areas in Chungcheongbuk-do' as they are conventionally known by their high degree of rural recession. According to the results of the clustering analysis carried out on the 166 Eups and Myuns, there were five outstanding clusters. They were; areas with housing deterioration (29), areas with poor economic foundation (16), areas with poor accessibility to central areas (42), areas with poor residential environment (51) and areas with aged population (28). The findings and results of the present study are likely to serve as a basis for the design and enforcement of forthcoming rural area activation policies. Also, it would be highly recommended that a more comprehensive diagnosis is taken from a community-level perspective and policy suggestions and strategies tailored for rural communities are further discussed.

• Korean Journal of Microbiology
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• v.49 no.4
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• pp.353-359
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• 2013

The objectives of this study were to investigate effectiveness of the Compressed Air Jet (CAJ) System for cleaning up shorelines contaminated with crude oils and to examine effects of the system on total petroleum hydrocarbon (TPH) removal and microbial community changes before and after remediation of the oil-contaminated shorelines. These data will lead to better understanding of optimized remediation process. About 66% of TPH reduction was observed when the contaminated site was treated with the CAJ System 2, 3, 4, and 5 times. This treatment system was more efficient than the seawater pumping system under similar treatment conditions (by 40%). By the way, little oil degrader communities were observed despite a potential function of the air jet system to stimulate aerobic oil degraders. The apparent low population density of the oil degraders might be as a result of low concentration of TPH as a carbon source and limiting nutrients such as nitrogen and phosphorus. It was proposed that the CAJ System would contribute significantly to removal of residual oils on the shorelines in combination with addition of these limiting nutrients.

• Korean Journal of Environmental Agriculture
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• v.37 no.2
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• pp.135-140
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• 2018

BACKGROUND: The Asian hornet (Vespa velutina nigrithorax), a wasp species, has attacked honey bee populations and affected the beekeeping industry in Korea over the past 15 years. However, little research has been done with this invasive species. In this study, we investigated the intestine bacterial microbiota of Asian hornets and honey bees to design an attractive trap for Asian hornets. METHODS AND RESULTS: Genomic DNAs isolated from the intestine microorganisms of Asian hornets and honey bees were utilized to amplify bacterial 16S rDNA for the comparative sequence analysis. The next generation sequencing analysis identified that the orders Flavobacteriales as the most abundant intestinal microorganisms in Asian hornets, showing a clear difference compared to honey bees in which Aeromonadales are dominant. We also report five newly identified 16S rDNA sequences of Asian hornet intestinal bacteria. According to the sequence blast search, these five bacteria belong to the genera Thalassomonas, Caedobacter, Vampirovibrio, Alkaliphilus and Calothrix. CONCLUSION: While Asian hornets and honey bees show similar intestine bacterial diversity, the relative ratio of bacterial populations is different. providing useful information to design pest control agents specifically targeting Asian hornets.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.6
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• pp.535-543
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• 2019

Recently, growing social interest in alley markets, which have shown rapid growth like Gyeonglidan-gil street in Seoul, has led to the need for an analysis of growth factors. This paper aims at exploring growing alley markets through time-series clustering using DTW (Dynamic Time Warping) and examining the growth factors through logistic regression. According to cluster analysis, the number of growing markets of the Northeast, the Southwest, and the Southeast were much more than the Northwest but the proportion in region of the Northwest, the Northeast, and the Southwest were much more than the Southeast. Logistic regression results show that people in 20s and 30s have a lower impact on sales than those in 50s, but have a greater impact on growth of alley market. Alley markets located in high-income areas often reached their growth limits, indicating a tendency to stagnate or decline. The proximity of a subway station effected positive on sales but negative on growth. This research is an advanced study in that the causes of sales growth of alley markets is examined, which has not been examined in the preceding study.

• Journal of Environmental Impact Assessment
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• v.25 no.6
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• pp.384-401
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• 2016

The vegetation assessment indicator has been developed recently as a biological part of the integrated assessment system for river environment to improve the efficiency of river restoration projects. This study carried out to test the vegetation assessment indicator and to reset its grade criteria on experimental streams. We classified and mapped vegetation communities at the level of physiognomic-floristic composition by each assessment unit. A total of 204 sampling quadrats were set up on the 68 assessment units at 5 experimental streams. By analyzing the vegetation data collected, we examined the appropriate numbers of sampling quadrats, the criteria of vegetation index score, classification of vegetation community, and grade criteria for vegetation assessment. The developed vegetation assessment indicator composed with the vegetation complexity index (VCI), the vegetation diversity index (VDI), and the vegetation naturalness index (VNI) was proved to reflect the current conditions of the streams sufficiently. The contribution of vegetation naturalness index to grading by vegetation assessment indicator was larger, but three indexes were closely correlated to each other. Also there was more clearer discrimination of grading with the application of adjusted criteria of vegetation assessment indicator and the standardized classification of vegetation community, but the stream segment type did not influence the vegetation assessment grade significantly.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.4
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• pp.124-137
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• 2018

The main purpose of this study is to find the hotspots of crimes that occur frequently in the space and to derive the appropriate CCTV installation location. One of the characteristics of crime is clustered around past occurrence area, and these crimes are strongly correlated. It is also possible to find the cause of the clusters and the variables that affect the crime through the history of the crime. In addition to the traditional OLS model, spatial differential model including spatial autocorrelation and spatial error model were used to select the variables influencing the five major crime rate, the theft rate and the foreign resident rate. The variables affecting the Five major crimes were positive (+) sign for the welfare and the rate of the bar cluster rate, and negative (-) for the street density. The CCTV area occupies 46% of the hotspots based on the overlapping of the areas where the elderly people are crowded, the bar cluster, many multicultural families, and the areas with low density of street lamps. It turned out. Taking into account the current CCTV operation, the total number of new cases to cover the risk point was 89.