• 근관절건강학회지
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• 제22권1호
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• pp.13-19
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• 2015

Purpose: The purpose of this study was to identify the relationships among network centrality, psychological well-being (PWBS), and intention to exercise maintenance in participants of an aquatic exercise program. Methods: Using a single-experimental design, 17 osteoarthritis patients participated in an aquatic exercise program. The questionnaire to connect the network of members was used to peer nomination by Moreno (1953). Data were analyzed with the UCINET using centrality (degree, closeness, betweenness) and SPSS using descriptive statistics, wilcoxon signed ranked test, and spearman's rho. Results: Closeness centrality, PWBS, and intention to exercise maintenance were significantly different between 4 weeks and 8 weeks. At 4 weeks, PWBS was positively correlated with closeness centrality. Intention to exercise maintenance was positively correlated with degree, closeness, and betweenness centrality. At 8 weeks, PWBS was positively correlated with closeness centrality. Intention to exercise maintenance was positively correlated with closeness centrality. Conclusion: The aquatic exercise program can be effective in increasing closeness centrality, psychological well-being, and intention to exercise maintenance. This was the first study attempted to analyze construction of member relationships in osteoarthritis patients participating an exercise program by using social network analysis.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권3호
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• pp.1454-1466
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• 2016

This paper implements an estimated ranking algorithm of closeness centrality measures in large-scale workflow-supported social networks. The traditional ranking algorithms for large-scale networks have suffered from the time complexity problem. The larger the network size is, the bigger dramatically the computation time becomes. To solve the problem on calculating ranks of closeness centrality measures in a large-scale workflow-supported social network, this paper takes an estimation-driven ranking approach, in which the ranking algorithm calculates the estimated closeness centrality measures by applying the approximation method, and then pick out a candidate set of top k actors based on their ranks of the estimated closeness centrality measures. Ultimately, the exact ranking result of the candidate set is obtained by the pure closeness centrality algorithm [1] computing the exact closeness centrality measures. The ranking algorithm of the estimation-driven ranking approach especially developed for workflow-supported social networks is named as RankCCWSSN (Rank Closeness Centrality Workflow-supported Social Network) algorithm. Based upon the algorithm, we conduct the performance evaluations, and compare the outcomes with the results from the pure algorithm. Additionally we extend the algorithm so as to be applied into weighted workflow-supported social networks that are represented by weighted matrices. After all, we confirmed that the time efficiency of the estimation-driven approach with our ranking algorithm is much higher (about 50% improvement) than the traditional approach.

• 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.

• 인터넷정보학회논문지
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• 제14권5호
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• pp.77-85
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• 2013

본 논문에서는 워크플로우 소셜 네트워크(WSSN, Workflow-supported Social Network) 근접중심성 분석 알고리즘을 제안한다. 워크플로우모델과 모델의 실행을 기반으로 형성되는 업무수행자들간의 협업 관계를 워크플로우 소셜 네트워크라고 정의하고, 이를 기존의 소셜 네트워크 근접중심성 분석기법을 적용하여 워크플로우 소셜 네트워크의 근접중심성을 분석하는 알고리즘을 설계한다. 특히, 제안한 알고리즘의 적용 사례를 통해 특정 워크플로우모델로부터 해당 워크플로우 소셜 네트워크 근접중심성을 분석함으로써 본 논문에서 제안한 알고리즘의 정확성 및 적합성을 검증한다.

• 응용통계연구
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• 제24권2호
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• pp.401-409
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• 2011

사회네트워크분석(social network analysis)은 l개 연결선을 갖는 n개 노드의 자료를 대상으로 한다. 기본적인 자료기술로서 노드 간 최단거리(shortest distance), 근접 중심성(closeness centrality), 중개 중심성(betweenness centrality) 등을 산출한다. 기존의 사회학적 연구에서 다룬 네트워크는 대개 노드 수 n이 수십 또는 수백 정도였으나 최근에는 그 크기가 수십만 또는 수백만에 이르는 경우가 드물지 않다. 이에 따라 사회네트워크분석에서도 자료 규모성(data scalability)의 이슈가 생겼다. 본 연구에서는 몬테칼로(Monte Carlo) 방법을 활용하여 n = 100,000 규모의 임의 네트워크의 작은 세상(small world) 성질을 실증적으로 탐구하고 그 정도 규모에서의 중개 중심성과 근접 중심성의 산출 방법을 제안하고자 한다.

• Communications for Statistical Applications and Methods
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• 제29권4호
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• pp.487-498
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• 2022

Social network analysis (SNA) techniques have recently been developed to monitor and detect abnormal behaviors in social networks. As a useful tool for process monitoring, control charts are also useful for network monitoring. In this paper, the degree and closeness centrality measures, in which each has global and local perspectives, respectively, are applied to an exponentially weighted moving average (EWMA) chart and a multinomial cumulative sum (CUSUM) chart for monitoring undirected weighted networks. In general, EWMA charts monitor only one variable in a single chart, whereas multinomial CUSUM charts can monitor a categorical variable, in which several variables are transformed through classification rules, in a single chart. To monitor both degree centrality and closeness centrality simultaneously, we categorize them based on the average of each measure and then apply to the multinomial CUSUM chart. In this case, the global and local attributes of the network can be monitored simultaneously with a single chart. We also evaluate the performance of the proposed procedure through a simulation study.

• 무역학회지
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• 제47권4호
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• pp.137-159
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• 2022

This study aims to analyze international trade papers published in Korea during the past 2002-2022 years. Through this study, it is possible to understand the main subject and direction of research in Korea's international trade field. As the research mythologies, this study uses the big data analysis such as the text mining and Social Network Analysis such as frequency analysis, several centrality analysis, and topic analysis. After analyzing the empirical results, the frequency of key word is very high in trade, export, tariff, market, industry, and the performance of firm. However, there has been a tendency to include logistics, e-business, value and chain, and innovation over the time. The degree and closeness centrality analyses also show that the higher frequency key words also have been higher in the degree and closeness centrality. In contrast, the order of eigenvector centrality seems to be different from those of the degree and closeness centrality. The ego network shows the density of business, sale, exchange, and integration appears to be high in order unlike the frequency analysis. The topic analysis shows that the export, trade, tariff, logstics, innovation, industry, value, and chain seem to have high the probabilities of included in several topics.

• Kyungpook Mathematical Journal
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• 제56권4호
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• pp.1191-1205
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• 2016

The emergence of various Internet worms, including the stand-alone Code Red worm that caused a distributed denial of service (DDoS), has prompted many studies on their propagation speed to minimize potential damages. Many studies, however, assume the same probabilities for initially infected nodes to infect each node during their propagation, which do not reflect accurate Internet worm propagation modelling. Thus, this paper analyzes how Internet worm propagation speed varies according to the number of vulnerable hosts directly connected to infected hosts as well as the link costs between infected and vulnerable hosts. A mathematical model based on centrality theory is proposed to analyze and simulate the effects of degree centrality values and closeness centrality values representing the connectivity of nodes in a large-scale network environment on Internet worm propagation speed.

• 인터넷정보학회논문지
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• 제16권3호
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• pp.71-77
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• 2015

본 논문에서는 대규모 워크플로우 기반 소셜 네트워크를 위한 추정 근접 중심도 랭킹 알고리즘을 구현하고, 그에 대한 성능 분석을 수행한다. 기존의 근접 중심도 분석 방법은 특정 노드와 다른 모든 노드들 간의 최단거리를 구하므로 네트워크의 크기가 커짐에 따라 근접 중심도 분석 시간이 기하급수적으로 증가하는 문제점을 가진다. 이로 인해 대규모 소셜 네트워크의 근접 중심도 랭킹 과정에도 계산시간 문제를 가진다. 이러한 문제점을 개선하고자 본 논문에서는 추정기법을 활용한 근접 중심도 랭킹 알고리즘을 구현하며 기존 알고리즘과의 성능 분석을 수행한다. 이는 약 50%의 계산 시간 단축 결과를 보여주었다.

• 인터넷정보학회논문지
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• 제17권1호
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• pp.47-53
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• 2016

워크플로우 소속성 네트워크는 워크플로우 기반 조직의 수행자와 업무 사이의 연관관계를 나타내는 소셜 네트워크의 한 형태이며, 이를 기반으로 연결 중심도, 근접 중심도, 사이 중심도, 위세 중심도 등과 같은 다양한 분석 기법들이 제안되었다. 특히, 전사적 워크플로우 모델을 기반으로 하는 소속성 네트워크의 근접 중심도 분석은 워크플로우 소속성 네트워크의 규모가 증가함에 따라, 중심도 및 랭킹 계산의 시간 복잡도 문제점을 가진다는 것을 발견하였다. 본 논문에서는 근접 중심도 분석의 시간 복잡도 문제를 개선하기 위해, 근사치 추정 방법을 이용한 워크플로우 기반 소속성 네트워크의 추정 근접 중심도 기반 랭킹 알고리즘을 제안한다. 노드의 타입이 수행자인, 워크플로우 예제 모델을 추정 근접 중심도 기반 랭킹 알고리즘에 적용한 성능 분석을 실시하였다. 수행 결과, 네트워크 규모 관점에서의 정확도는 평균적으로 47.5% 향상되었고, 샘플 모집단 비율 관점에서는 평균적으로 9.44%정도의 향상된 수치를 보였다. 또한, 추정 근접 중심도 랭킹 알고리즘의 평균 계산 시간은 네트워크의 노드 수가 2400개, 샘플 모집단의 비율이 30%일 때, 기존 근접 중심도 랭킹 알고리즘의 평균 계산 시간보다 82.40%의 높은 성능을 보였다.