• Ecology and Resilient Infrastructure
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• v.4 no.1
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• pp.34-43
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• 2017

The Naeseong Stream as a tributary of Nakdong River has conserved the unique structure and function of a typical sand-bed stream ecosystem. However, it is expected to change the stream bed environments and then the fish fauna in the downstream of the dam after the operation of the Yeongju Dam from 2016. We collected fishes and investigated their habitat environments from 2014 to 2016 in the downstream of the Yeongju Dam under construction in order to monitor changes in habitat environment, fauna and community structure of fishes in the Naeseong Stream. The size of the bed materials increased immediately downstream of the Yeongju Dam under construction. Before the operation of the Yeongju Dam, Zacco platypus was dominated and Opsarichthys uncirostris amurensis, Coreoleuciscus splendidus, Hemibarbus longirostris and Pseudogobio esocinus were sub-dominated according to the different sampling sites. Hemibarbus labeo, H. longirostris, Pseudogobio esocinus, Gobiobotia nakdongensis, Cobitis hankugensis and Leiocassis ussuriensis were found as a psammophilous fish specific to sand stream in the Naeseong Stream. At the downstream of the dam, the fish community was classified into a group of gravel-bed fishes such as Microphysogobio yaluensis, Coreoleuciscus splendidus and Coreoperca herzi and a group of sand-bed fishes such as Hemibarbus labeo, Cobitis hankugensis and Gobiobotia nakdongensis. These fish communities gradually tended to change from sand-bed fish community to gravel-bed fish community during the construction of the Yeongju Dam. Therefore, it is necessary to collect the baseline data for the stream ecosystem conservation in the sandy stream by continuously monitoring changes in the environment and fish in the downstream of the Youngju Dam.

• Ocean and Polar Research
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• v.28 no.2
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• pp.79-94
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• 2006

Spatio-temporal patterns in the zooplankton communities, physicochemical environmental factors, and dominant species were examined in Camak Bay from April, July, September, and November, 2003. A total of 40 taxa were sampled with a mean abundance of total zooplankton ranging from $270{\sim}1,803inds/m^3$. The most abundant species was Acartia erythraea, followed by Eurytemora pacifica, Podon polyphemoides, A. omorii, and Paracalanus parvus s. 1 during the study period. Multivariate analysis revealed significant differences in community structure among three regions: the middle part of the sampling area (B), sites 1, 2 (A) and other sites (C). The number of species and diversity (H') varied significantly among the three regions (p<0.05), but no differences in the mean abundances were observed (p>0.05). In order to investigate factors affecting the correlations between the abundance of dominant species, all zooplankton and environmental factors ware calculated using a correlation analysis. Of these, the abundance of dominant taxon showed positive correlation with seawater temperature, salinity and dissolved oxygen (p<0.05). In statistical analysis showed that the environmental factors influencing the variation of the communities ere predominantly temperature, salinity, and dissolved oxygen.

• Journal of Korean Society of Transportation
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• v.36 no.2
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• pp.98-111
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• 2018

Truck platooning, which is a cluster of trucks in support of vehicle-to-vehicle communication and automated longitudinal vehicle control, is a promising method to both operational efficiency and prevent traffic crashes. Although a variety of studies have been conducted to identify the effects of vehicle platooning on traffic stream, we are not aware of any study attempting to identify promising road segments for vehicle platooning. This study aims to develop a methodology for determining the priority of freeway segments that would potentially lead to maximize the effectiveness of truck platooning. Evaluation measures derived in this study includes truck crash rates, the percentage of truck traffic, segment length, and the number of entry and exit points. Weighting values obtained from an analytical hierarchical process (AHP) method were applied to compute the proposed priority score to determine better freeway segment for truck platooning. Results suggested that a 46.9km freeway segment, from Sacheon IC to Sanin JC, was the most promising segment for maximizing the effectiveness of truck platooning. It is expected that the outcome of this study would be effectively used as a fundamental to establish operational strategies for truck platooning.

• Journal of Korean Society of Forest Science
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• v.104 no.4
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• pp.519-526
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• 2015

This study was investigated to analyze stand structure in Daegu Dodong T.orientalis Forest for conservation Thuja orientalis forest. Results of cluster analysis, it was classified to Quercus variabilis group(A), Quercus variabilis-Quercus mongolica group(B), Pinus densiflora group(C), Thuja orientalis group(D). Charaters of location environments for D group were analyzed that altitude 99.3 m, slope $59^{\circ}$, rock exposure 68.3%, BHA $21.8m^2/ha$ and North West aspects. The MRPP-test, It classified groups, appropriately. Importance value of D group was T. orientalis 85.42, Q. variabilis 1.28, P.densiflora 1.30, Fraxinus rhynchophylla 3.56 etc. DBH classes of D group were expressed inverted-J-shaped curve. H' was resulted in 0.600~0.834, H'max 1.317~1.466, J' 0.456~0.594, D' 0.405~0.544. Indecator species Analysis were conducted that woody plants were 4 taxa, Herbal plants 9 taxa.

• Journal of Korea Port Economic Association
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• v.34 no.3
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• pp.17-52
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• 2018

The purpose of this paper is to measure the clustering change and analyze empirical results. Additionally, by using k-means, hierarchical, and mixed models on Asian container ports over the period 2006-2015, the study aims to form a cluster comprising Busan, Incheon, and Gwangyang ports. The models consider the number of cranes, depth, birth length, and total area as inputs and container twenty-foot equivalent units(TEU) as output. Following are the main empirical results. First, ranking order according to the increasing ratio during the 10 years analysis shows that the value for average linkage(AL), mixed ward, rule of thumb(RT)& elbow, ward, and mixed AL are 42.04% up, 35.01% up, 30.47%up, and 23.65% up, respectively. Second, according to the RT and elbow models, the three Korean ports can be clustered with Asian ports in the following manner: Busan Port(Hong Kong, Guangzhou, Qingdao, and Singapore), Incheon Port(Tokyo, Nagoya, Osaka, Manila, and Bangkok), and Gwangyang Port(Gungzhou, Ningbo, Qingdao, and Kasiung). Third, optimal clustering numbers are as follows: AL(6), Mixed Ward(5), RT&elbow(4), Ward(5), and Mixed AL(6). Fourth, empirical clustering results match with those of questionnaire-Busan Port(80%), Incheon Port(17%), and Gwangyang Port(50%). The policy implication is that related parties of Korean seaports should introduce port improvement plans like the benchmarking of clustered seaports.

• Journal of Korean Society of Forest Science
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• v.86 no.2
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• pp.146-157
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• 1997

To investigate the structure and the conservation strategy of Korean native species, Abies koreana forest at Cheonwangbong-Deokpyungbong area in Chirisan National Park, 48 plots($10{\times}10m$) were set up with random sampling method. Three groups - Abies koreana community, Abies koreana-Quercus mongolica community, Picea jezoensis-Betula ermanii community - were classified by cluster analysis. High positive correlations were shown between Picea jezoensis and Sorbus commixta : Quercus mongodica and Fraxinus sieboldiana, Symplocos chinensis : Euonymus macroptera and Vaccinium koreanum, and high negative correlations were shown between Quereus mongolica and Sorbus commixta. Species diversity(H') of investigated area was calculated 0.7208-1.2074. Vigor of Abies koreana was depressed, 12.24 of total number of Abies koreana investigated were dead. DBH of dead individuals ranged mainly 10-30cm.

• The Korean Journal of Applied Statistics
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• v.20 no.2
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• pp.387-394
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• 2007

This paper considers several stratification strategies for multivariate and multipurpose survey with several quantitative stratification variables. We propose three methods of stratification based on, respectively, the method of cumulative frequency square root which is the most popular one in univariate stratification, cluster analysis, and factor analysis followed by cluster analysis. We then compare the efficiency of those methods using the Dong-Eup-Myun data of the holding numbers of farming machines, extracted from the 2001 Agricultural Census. It turned out that the method based on cluster analysis with factor analysis would be a relatively satisfactory strategy.

• Journal of the Korean Data and Information Science Society
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• v.26 no.6
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• pp.1239-1247
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• 2015

In this study, 64 administrative regions with high frequencies of apartment trade in Seoul, Korea are classified by the apartment sale price. To consider distributions of apartment price for each region as well as the mean of the price, the symbolic histogram-valued data approach is employed. Symbolic data include all types of data which have internal variation in themselves such as intervals, lists, histograms, distributions, and models, etc. As a result of the cluster analysis using symbolic histogram data, it is found that Gangnam, Seocho, and Songpa districts and regions near by those districts have relatively higher prices and larger dispersions. This result makes sense because those regions have good accessibility to downtown and educational environment.

• Journal of the Korean Data and Information Science Society
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• v.20 no.3
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• pp.551-562
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• 2009

In this paper, I would present a using method for The Fishing Operation Information(FOI) of National Federation of Fisheries Cooperatives(NFFC) through the availabilities analysis and put out the similarities by the section of the sea through classifying characteristics of fishing patterns by their locations. As a result, although the catch of FOI is nothing more than 33% level to National Fishery Production Statistics(NFPS), FOI data is useful in understanding the patterns of fishing operation by the location because both patterns and correlation were very similar in the usability analysis, comparing the FOI data with NFPS. So I classified optimal clusters for catch, the number of fishing days and the number of fishing vessels through 2 step cluster analysis by the big marine zone and divided fishing patterns.

• Journal of the Korean GEO-environmental Society
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• v.11 no.6
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• pp.57-67
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• 2010

Specific yield is an essential parameter of the water table fluctuation method for recharge calculation. Specific yield is not easily estimated because of limited availability of aquifer test data and soil samples at National Groundwater Monitoring Stations in South Korea. The linear relationship between rainfall and water level rise was used to estimate the specific yields of aquifer for 34 shallow monitoring wells which were grouped into three clusters. In the case of Cluster-1 and Cluster-2, this method was not applicable because of low cross correlation between rainfall and water level rise and also a long lag time of water level rise to rainfall. However, the specific yields for 19 monitoring wells belonging to Cluster-3, which have relatively high cross correlation and short lag time, within 2 days after rainfall, range from 0.06 to 0.27 with mean value of 0.17. These values are within the general range for sand and gravel sediments and similar to those from aquifer test data. A detailed field survey is required to identify monitoring sites that are not greatly affected by pumping, stream flow, evapotranspiration, or delayed response of water levels to rainfall, because these factors may cause overestimation of specific yield estimates.