• 한국지역사회생활과학회지
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• 제24권4호
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• pp.553-565
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• 2013

The purpose of this study is to segment urban farming patterns and analyse the preference on urban farming by applying two-step cluster analysis, chi-square analysis and ANOVA. The data was collected by face-to-face surveys on 9 urban farms which were chosen by location and operator. Respondents were asked to describe their urban farming pattern, preference on urban farming and socio-demographic characteristics. Three different clusters were derived from two-step cluster analysis based on operator, transportation, number of visits per month, travel time, area and motive. They were 'hobby-oriented farming', 'producing-oriented farming', and 'multipurpose farming'. The results of chi-square analysis showed that there were significant differences among these three segmented groups in terms of age, with or without children aged under 14, household income per month and housing type. In other words, there is quite a possibility that urbanites have different urban farming patterns according to their socio-demographic profiles. Also, there were significant differences on the preference on urban farming by cluster. According to the results, planning directions of urban farming were presented.

• 한국지역사회생활과학회지
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• 제21권4호
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• pp.619-631
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• 2010

The purpose of this study is to segment and examine urban farmers behavior by applying a two-step cluster analysis and multi-nominal logit model. The data were collected by a telephone survey with two-staged stratified random sampling in the cities around the country for the purpose of acquiring representative data. Respondents were asked to describe their awareness of urban agriculture, their agricultural activity, and sociodemographic characteristics. Among 2,000 cases, 381 cases(19.1%) which were of participants in urban agriculture were analysed in SPSS. From the findings, 27.3% of respondents had heard the word 'urban agriculture', and 25.5% of them regarded themselves as urban farmers. Four different clusters were derived from two-step clusters based on motive, place, companion, area and hours. They were 'Large scale hobby farming(cluster 1)', ‘Weekend farm/ hobby farming(cluster 2)', 'Land/ Self-supporting farming(cluster 3)', and 'Small scale hobby farming(cluster 4)'. The result of multinomial logistic regression showed that there were significant differences among these four segmented groups in terms of age, city size and housing type. In other words, there is quite a possibility that urbanites select different urban farming types according to their socio-demographic profiles. Therefore, the urbanite profiles can be used as the basis for promoting policy of several urban agriculture types. According to the result, policy directions for facilitating urban agriculture were presented.

• Communications for Statistical Applications and Methods
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• 제21권3호
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• pp.225-234
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• 2014

We propose a novel hierarchical clustering for distribution valued dissimilarities. Analysis of large and complex data has attracted significant interest. Symbolic Data Analysis (SDA) was proposed by Diday in 1980's, which provides a new framework for statistical analysis. In SDA, we analyze an object with internal variation, including an interval, a histogram and a distribution, called a symbolic object. In the study, we focus on a cluster analysis for distribution valued dissimilarities, one of the symbolic objects. A hierarchical clustering has two steps in general: find out step and update step. In the find out step, we find the nearest pair of clusters. We extend it for distribution valued dissimilarities, introducing a measure on their order relations. In the update step, dissimilarities between clusters are redefined by mixture of distributions with a mixing ratio. We show an actual example of the proposed method and a simulation study.

• 한국정보컨버전스학회:학술대회논문집
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• 한국정보컨버전스학회 2008년도 International conference on information convergence
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• pp.43-46
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• 2008

Centrality has been actively studied in network analysis field. In this paper we show a calculation method of closeness centrality for WSN. Since nodes in a sensor network are very scarce in energy and computation capability the calculation of the closeness is done in two tiers by dividing network into clusters. In first step closeness centrality for cluster heads is calculated. In the second step closeness of member nodes of the chosen cluster is computed in respect to that cluster itself.

• 한국정보시스템학회지:정보시스템연구
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• 제26권4호
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• pp.227-246
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• 2017

Purpose: As the importance of software has been emphasized recently, the size of the software market is continuously expanding. The development of the software market is being adversely affected by software piracy. In this study, we try to classify countries around the world based on the macro environmental factors, which influence software piracy. We also try to identify the differences in software piracy for each classified type. Design/methodology/approach: The data-driven approach is used in this study. From the BSA, the World Bank, and the OECD, we collect data from 1990 to 2015 for 127 environmental variables of 225 countries. Cronbach's ${\alpha}$ analysis, item-to-total correlation analysis, and exploratory factor analysis derive 15 constructs from the data. We apply two-step approach to cluster analysis. The number of clusters is determined to be 5 by hierarchical cluster analysis at the first step, and the countries are classified by the K-means clustering at the second step. We conduct ANOVA and MANOVA in order to verify the differences of the environmental factors and software piracy among derived clusters. Findings: The five clusters are identified as underdeveloped countries, developing countries, developed countries, world powers, and developing country with large market. There are statistically significant differences in the environmental factors among the clusters. In addition, there are statistically significant differences in software piracy rate, pirated value, and legal software sales among the clusters.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.111-111
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• 2016

Two step PEO ceramic coatings were formed on AZ91 magnesium alloy in $ZrO_2$ nanoparticles and $K_2ZrF_6$ based colloidal electrolyte solution for various voltages. Surface and layers tructure of the coatings was analyzed using SEM (ScanningElectronMicroscope). Structure analysis revealed that surface of the coating was transferred from individual pancake or craters-based structure to cluster-based structure with increasing the voltage of the secondary step process. Further, it was confirmed that the cluster zone was richin Zr-based complexes and formed due to high intensives parks. Increase in the Zr contents as discovered from the EDS analysis confirmed the rise in amorphous form of the Zr-based species, which justified the results of XRD where no increase in the intensity of Zr-based species was observed with increase in voltage. Potentiodynamic polarizariotion and impedance spectroscopy techniques were used to evaluate the corrosion performance of the coatings. The highest corrosion resistance was found for coatings prepared at 240V. The same specimen was found having highest and uniform vickers hardness ~1070.5 HV. The superior mechanical and electrochemical properties of the said coating can be attributed to the defect-less microstructure and the optimal role of $ZrO_2$ nanoparticles in the secondary PEO process at 240V.

• 동아시아경상학회지
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• 제7권2호
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• pp.21-30
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• 2019

Purpose - In this work, we categorize the 21 shopping items which foreign tourists purchase in South Korea and monitor the level of dissimilarity (or similarity) between each item by utilizing distance matrix, and both hierarchical and k-means cluster analyses, respectively, based on several purpose of visit attributes in 2017. In addition, multidimensional scaling (MDS) method is applied for mining visual appearance of proximities among shopping items based on purpose of visit attributes. Research design and methodology - This study is carried out in 2017 by Ministry of Culture, Sports and Tourism and conduct a face-to-face survey of foreign tourists from 20 countries who purchase shopping items in South Korea. CLUSTER, PROXIMITIES and ALSCAL modules in IBM SPSS 23.0 are used to perform this work. Results - We ascertain that 21 shopping items can be classified into five similar groups which have homogeneous traits by going through two-step cluster analysis. We can position homogeneous places of cluster and shopping items joining each cluster. Conclusions - We can relatively assess patterns and characteristics of each shopping item, come by useful information in activating shopping tour based on the actual state of recognition of foreign tourists and practically apply to each tourism industry on underlying results.

• Journal of Information Technology Applications and Management
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• 제26권1호
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• pp.53-64
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• 2019

The purpose of this study is to find out the fast delivery route that several drones return a truck again after departing from it for delivery locations at each cluster while the truck goes through the cluster composed of several delivery locations. The main issue is to reduce the total delivery time composed of the delivery time by relatively slow trucks via clusters and the sum of maximum delivery times by relatively fast drones in each cluster. To solve this problem, we use a three-step heuristic approach. First, we cluster the nearby delivery locations with minimal number of clusters satisfying a constraint of drone flight distance to set delivery paths for drones in each cluster. Second, we set an optimal delivery route for a truck through centers of the clusters using the TSP model. Finally, we find out the moved centers of clusters while maintaining the delivery paths for the truck and drones and satisfying the constraint of drone flight. distance in the two-dimensional region to reduce the total delivery time. In order to analyze the effect of this study model according to the change of the number of delivery locations, we developed a R-based simulation prototype and compared the relative efficiency, and performed paired t-test between TSP model and the cluster-based models. This study showed its excellence through this experimentation.

• 한국지능시스템학회논문지
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• 제10권4호
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• pp.285-292
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• 2000

자료 분석 과정을 살펴 보면 1) 자료가 갖는 경향 평가, 2) 클러스터 분석, 3) 클러스터의 타당성 조사라는 과정을 거쳐 이루어진다. 이 분석법은 2) 및 3) 단계의 반복 수행으로 인하여 많은 계산 시간이 소요되므로 비효율적인 방법이라 할 수 있다. 본 논문에서는, 이와 같은 단점을 보완하기 위하여 자료가 갖는 개략적 특성을 파악하여 자료 속에 존재하는 클러스터의 근사적 개수 및 중심을 정한 후, 이 정보를 기존의 일반적인 퍼지 클러스터링 알고리즘에 입력하여 클러스터링을 수행하는 밀도함수를 이용한 계층적 구조의 근사적 클러스터링 알고리즘을 제안하고, 예제를 통하여 제안된 알고리즘의 타당성을 보인다.

• 사회복지연구
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• 제47권4호
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• pp.333-360
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• 2016

본 연구는 전세계 42개 SIB 사업의 운영구조를 검토하고, 주요 단계별 핵심기준을 중심으로 유형화 분석을 실시하였으며, 이를 토대로 SIB의 향후 방안에 대해 모색하였다. 분석의 결과는 다음과 같다. 첫째, SIB의 기획은 중앙정부의 부처가 기획한 경우가 과반수 이상을 차지하고 있었다. 투자자 구성은 2-3개 조직이 공동투자하는 경우가 일반적이었는데, 이 때 사회적금융조직이 투자자로 포함된 경우가 54.8%로 가장 많았지만, 민간 투자은행이나 고액 투자자가 참여하는 경우도 33.3%로 나타났다. 둘째, 서비스의 제공은 단일조직에서 수행하는 경우가 전체 분석사례 중 73.8%였고, 제공되는 서비스 중에서 74%가 아동과 청소년을 대상으로 하고 있었다. 셋째, 성과평가는 특정기준에 도달할 경우 성과를 지급하는 방식인 '성과표' 방식이 전체 사례 중 64.3%로 가장 많았지만, 유사한 집단과의 비교를 통해 성과를 평가하는 경우도 23.8%나 존재했다. 넷째, 유형화 분석 결과 세 개의 유형이 도출되었다. 첫번째로 도출된 유형은 '중앙정부-사회적 금융 결합형'으로서 중앙정부가 기획하고 사회적 금융조직이 주요한 투자자가 되면서 성과표를 중심으로 성과급을 지급하는 형태이다. 두 번째로 도출된 유형은 '복합참여형'으로서, SIB의 단계별로 참여하는 주체들이 가장 다양할 뿐만 아니라, 성과평가 과정에서도 가장 체계적인 절차를 보여주고 있다. 서비스는 주로 단일 기관에서 제공되고 있지만, 비교집단을 통한 유사실험설계를 활용한 성과평가를 하는 것이 특징이다. 마지막 유형은 '서비스기관 다수형'으로서, 유형의 고유한 특이점이 발견되지는 않았으나, 서비스를 제공하는 기관이 복수라는 공통점이 있었다. SIB에 대한 통계적 유형화를 처음으로 시도한 본 연구는 운영구조에 대한 개괄적 설명이나 단순나열식 비교에서 더 나아가지 못하고 있는 SIB 관련 연구를 보다 체계화시켰다는 의의가 있다. 또한, SIB를 기획하는데 있어 주요 단계별 고려해야 하는 이슈 및 쟁점에 대해 구체적인 정보를 제공하였으며, 지방정부나 민간조직이 SIB를 기획하는 경우에는 투자자 구성이나 참여하는 주체의 만족을 위하여 성과평가 및 관리와 관련된 방안을 보다 체계적으로 구성하는 것이 효과적인 전략임을 제안하였다. 뿐만 아니라 본 연구는 SIB의 등장 배경인 다양한 주체간 협치와 네트워크가 보다 활발하게 전개되기 위해서는 기획자나 투자자 구성이 보다 확대될 필요가 있음을 제안하였다.