• Title/Summary/Keyword: social network density

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Social Network Analysis for the Effective Adoption of Recommender Systems (추천시스템의 효과적 도입을 위한 소셜네트워크 분석)

  • Park, Jong-Hak;Cho, Yoon-Ho
    • Journal of Intelligence and Information Systems
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    • v.17 no.4
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    • pp.305-316
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    • 2011
  • Recommender system is the system which, by using automated information filtering technology, recommends products or services to the customers who are likely to be interested in. Those systems are widely used in many different Web retailers such as Amazon.com, Netfix.com, and CDNow.com. Various recommender systems have been developed. Among them, Collaborative Filtering (CF) has been known as the most successful and commonly used approach. CF identifies customers whose tastes are similar to those of a given customer, and recommends items those customers have liked in the past. Numerous CF algorithms have been developed to increase the performance of recommender systems. However, the relative performances of CF algorithms are known to be domain and data dependent. It is very time-consuming and expensive to implement and launce a CF recommender system, and also the system unsuited for the given domain provides customers with poor quality recommendations that make them easily annoyed. Therefore, predicting in advance whether the performance of CF recommender system is acceptable or not is practically important and needed. In this study, we propose a decision making guideline which helps decide whether CF is adoptable for a given application with certain transaction data characteristics. Several previous studies reported that sparsity, gray sheep, cold-start, coverage, and serendipity could affect the performance of CF, but the theoretical and empirical justification of such factors is lacking. Recently there are many studies paying attention to Social Network Analysis (SNA) as a method to analyze social relationships among people. SNA is a method to measure and visualize the linkage structure and status focusing on interaction among objects within communication group. CF analyzes the similarity among previous ratings or purchases of each customer, finds the relationships among the customers who have similarities, and then uses the relationships for recommendations. Thus CF can be modeled as a social network in which customers are nodes and purchase relationships between customers are links. Under the assumption that SNA could facilitate an exploration of the topological properties of the network structure that are implicit in transaction data for CF recommendations, we focus on density, clustering coefficient, and centralization which are ones of the most commonly used measures to capture topological properties of the social network structure. While network density, expressed as a proportion of the maximum possible number of links, captures the density of the whole network, the clustering coefficient captures the degree to which the overall network contains localized pockets of dense connectivity. Centralization reflects the extent to which connections are concentrated in a small number of nodes rather than distributed equally among all nodes. We explore how these SNA measures affect the performance of CF performance and how they interact to each other. Our experiments used sales transaction data from H department store, one of the well?known department stores in Korea. Total 396 data set were sampled to construct various types of social networks. The dependant variable measuring process consists of three steps; analysis of customer similarities, construction of a social network, and analysis of social network patterns. We used UCINET 6.0 for SNA. The experiments conducted the 3-way ANOVA which employs three SNA measures as dependant variables, and the recommendation accuracy measured by F1-measure as an independent variable. The experiments report that 1) each of three SNA measures affects the recommendation accuracy, 2) the density's effect to the performance overrides those of clustering coefficient and centralization (i.e., CF adoption is not a good decision if the density is low), and 3) however though the density is low, the performance of CF is comparatively good when the clustering coefficient is low. We expect that these experiment results help firms decide whether CF recommender system is adoptable for their business domain with certain transaction data characteristics.

A Study on the Types of Social Networks of Housewives in Urban Nuclear Families (가족의 사회관계망 유형화 연구 - 도시 핵가족 주부를 중심으로 -)

  • 원효종;옥선화
    • Journal of Families and Better Life
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    • v.20 no.4
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    • pp.149-164
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    • 2002
  • The purpose of this study was to identify the types of social networks of urban housewives according to different network composition patterns and to analyze the structural and functional characteristics of identified types. The data used in this study were collected from 589 full-time housewives residing in Taejeon city. The major findings are as follows: 1) The social networks of housewives in urban nuclear families were classified into eight types: the kin network, the non-kin network, the kin-centered network, the friend-centered network, the neighbor-centered network, the associate-centered network, the parallel network, and the decentralized network. 2) The structual characteristics (size, density, homogeneity, duration, proximity, frequency, closeness, direction) varied according to the type. The kin network type and the non-kin network type showed extreme degrees in network characteristics. The parallel network type and the decentralized network type showed an average level of network characteristics. The kin-, friend-, neighbor-, and the associate-centered types showed network characteristics of an intermediate level between the single-category types and the decentralized type. 3) The average levels of function of social network types were different in only two(service support, interference) of the six function areas(emotional support, service support, material support, information support, social companionship support, interference). The average level of service support by the non-kin network type was higher than other types. The average level of interference by the kin-centered network type was higher than other types, and that of the neighbor-centered network type was lower than other types. On the other hand, the total amount of function performance of social network types was different in all function areas. The total amount of social support given by the decentralized network type was greater than the other types. The total amount of interference given by the non-kin network type was smaller than the other types.

Social Network Effects on Post-Traumatic Stress Disorder (PTSD) in Female North Korean Immigrants

  • Lee, Byung-Kyu;Youm, Yoo-Sik
    • Journal of Preventive Medicine and Public Health
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    • v.44 no.5
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    • pp.191-200
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    • 2011
  • Objectives: The goal of this paper is to examine the social network effects on post-traumatic sdress disorder (PTSD) in female North Korean immigrants who entered South Korea in 2007. Specifically, it attempts to verify if the density and composition of networks make a difference after controlling for the network size. Methods: A multivariate logistic regression is used to probe the effects of social networks using the North Korean Immigrant Panel data set. Because the data set had only completed its initial survey when this paper was written, the analysis was cross-sectional. Results: The size of the support networks was systematically related to PTSD. Female North Korean immigrants with more supporting ties were less likely to develop PTSD, even after controlling for other risk factors (odds-ratio for one more tie was 0.8). However, once we control for the size of the network, neither the density nor the composition of the networks remains statistically significant. Conclusions: The prevalence of the PTSD among female North Korean immigrants is alarmingly high, and regardless of the characteristics of supporting network members, the size of the supporting networks provides substantial protection. This implies that a simple strategy that focuses on increasing the number of supporting ties will be effective among North Korean immigrants who entered South Korea in recent years.

Evaluation of Coordination of Emergency Response Team through the Social Network Analysis. Case Study: Oil and Gas Refinery

  • Mohammadfam, Iraj;Bastani, Susan;Esaghi, Mahbobeh;Golmohamadi, Rostam;Saee, Ali
    • Safety and Health at Work
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    • v.6 no.1
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    • pp.30-34
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    • 2015
  • Background: The purpose of this study was to examine the cohesions status of the coordination within response teams in the emergency response team (ERT) in a refinery. Methods: For this study, cohesion indicators of social network analysis (SNA; density, degree centrality, reciprocity, and transitivity) were utilized to examine the coordination of the response teams as a whole network. The ERT of this research, which was a case study, included seven teams consisting of 152 members. The required data were collected through structured interviews and were analyzed using the UCINET 6.0 Social Network Analysis Program. Results: The results reported a relatively low number of triple connections, poor coordination with key members, and a high level of mutual relations in the network with low density, all implying that there were low cohesions of coordination in the ERT. Conclusion: The results showed that SNA provided a quantitative and logical approach for the examination of the coordination status among response teams and it also provided a main opportunity for managers and planners to have a clear understanding of the presented status. The research concluded that fundamental efforts were needed to improve the presented situations.

An Analysis of the Cruise Courses Network in Asian Regions Using Social Network Analysis (SNA를 이용한 아시아 지역 크루즈 항로의 네트워크 분석에 관한 연구)

  • Jeon, Jun-Woo;Cha, Young-Doo;Yeo, Gi-Tae
    • Journal of Korea Port Economic Association
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    • v.32 no.1
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    • pp.17-28
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    • 2016
  • This study examines the cruise course network structure in the Asian regions and the centrality of ports using social network analysis (SNA). For network analysis of Asian cruise courses, a data network of cruise courses was constructed using data on courses of cruise ships operating in Asian ports collected from the reports of the Cruise Lines International Associations.There are 249 nodes or ports of ship companies that provide cruise courses to Asia between from October 2015 to June 2016, and these nodes connect 545 ports. Density analysis based on ports where cruise ship companies operated cruise ships showed that, from October 2015 to June 2016, the density was 0.009, which was lower than the average of global port network density (2006 to 2011) and railroad network density. In addition, was calculated to be, which means that connection with all ports was possible through 2,180 steps. In the analysis of the Asian cruise course network centrality, Singapore ranked first in both out-degree and in-degree in connection centrality, followed by Hong Kong, Shanghai, Ho Chi Minh, and Keelung. Singapore also ranked first in the result betweenness centrality analysis, followed by Penang, Dubai, and Hong Kong. From October 2015 to June 2016, the port with the highest Eigenvector centrality was Hong Kong, followed by Ho Chi Minh, Singapore, Shanghai, and Danang. In the case of the domestic ports Incheon, Busan, and Jeju, connection centrality, betweenness centrality, and Eigenvector centrality all ranked lower than their competitor Chinese ports.

A Study on the Social Network Characteristics in Press Organizations of Korea (국내 언론사 조직에 내재한 사회적 네트워크 특성 연구 -국민정부에서 실용정부까지 신문사와 방송사 조직에서의 밀도 및 위치 분석을 중심으로)

  • Kwon, Jang-Won
    • Korean journal of communication and information
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    • v.67
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    • pp.7-34
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    • 2014
  • This study analyzes the characteristics, implications, and problems of Social Network of Press Organizations from the Kim Dae-jung administration to the Lee Myung-bak administration in Korea. For analyzing these issues, this study attempts to investigate the traits of social network structure based on the density analysis, distribution character analysis and correspondence analysis in each and among regimes. To answer these questions, this study utilizes human relationship data which related to personal network aspects (place of birth, affiliated college) and expertise aspects (types of major field), and which data has been gathered from the biographical web-site of Press Organizations in Korea. The results showed that the membership format of each Press Organizations depends on the connection with political environment directly and indirectly. Especially, the network traits of Broadcasting Press Organizations stands out a place of birth aspect. This findings indicate that the broadcasting policy reality that the path of decision making is connected with the political environment is more effective.

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A Comparative Study of Information Delivery Method in Networks According to Off-line Communication (오프라인 커뮤니케이션 유무에 따른 네트워크 별 정보전달 방법 비교 분석)

  • Park, Won-Kuk;Choi, Chan;Moon, Hyun-Sil;Choi, Il-Young;Kim, Jae-Kyeong
    • Journal of Intelligence and Information Systems
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    • v.17 no.4
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    • pp.131-142
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    • 2011
  • In recent years, Social Network Service, which is defined as a web-based service that allows an individual to construct a public or a semi-public profile within a bounded system, articulates a list of other users with whom they share connections, and traverses their list of connections. For example, Facebook and Twitter are the representative sites of Social Network Service, and these sites are the big issue in the world. A lot of people use Social Network Services to connect and maintain social relationship. Recently the users of Social Network Services have increased dramatically. Accordingly, many organizations become interested in Social Network Services as means of marketing, media, communication with their customers, and so on, because social network services can offer a variety of benefits to organizations such as companies and associations. In other words, organizations can use Social Network Services to respond rapidly to various user's behaviors because Social Network Services can make it possible to communicate between the users more easily and faster. And marketing cost of the Social Network Service is lower than that of existing tools such as broadcasts, news papers, and direct mails. In addition, Social network Services are growing in market place. So, the organizations such as companies and associations can acquire potential customers for the future. However, organizations uniformly communicate with users through Social Network Service without consideration of the characteristics of the networks although networks have different effects on information deliveries. For example, members' cohesion in an offline communication is higher than that in an online communication because the members of the offline communication are very close. that is, the network of the offline communication has a strong tie. Accordingly, information delivery is fast in the network of the offline communication. In this study, we compose two networks which have different characteristic of communication in Twitter. First network is constructed with data based on an offline communication such as friend, family, senior and junior in school. Second network is constructed with randomly selected data from users who want to associate with friends in online. Each network size is 250 people who divide with three groups. The first group is an ego which means a person in the center of the network. The second group is the ego's followers. The last group is composed of the ego's follower's followers. We compare the networks through social network analysis and follower's reaction analysis. We investigate density and centrality to analyze the characteristic of each network. And we analyze the follower's reactions such as replies and retweets to find differences of information delivery in each network. Our experiment results indicate that density and centrality of the offline communicationbased network are higher than those of the online-based network. Also the number of replies are larger than that of retweets in the offline communication-based network. On the other hand, the number of retweets are larger than that of replies in the online based network. We identified that the effect of information delivery in the offline communication-based network was different from those in the online communication-based network through experiments. So, you configure the appropriate network types considering the characteristics of the network if you want to use social network as an effective marketing tool.

The Effect of Problem Based Learning on Nursing Students' Interaction and Self-directed Learning: A Social Network Analysis (문제중심학습방법이 대학생들의 학습자 상호작용 및 자기주도학습능력에 미치는 영향: 사회연결망 분석을 중심으로)

  • Piao, Mei Hua;Kim, Jeong Eun
    • Perspectives in Nursing Science
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    • v.13 no.1
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    • pp.29-35
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    • 2016
  • Purpose: This study aimed to explore the underlying structures of students' interaction networks to monitor network changes during the year, to verify the relationship with self-directed learning, and to identify the effect of problem-based learning on interaction and self-directed learning. Methods: A longitudinal study was designed which included 3 parts (A=25, B=27, C=26) with a total of 78 second-year nursing students from 2013 to 2014. Interaction indicators used group network centralization and density, and individual in-degree centrality. Results: Group network centralization showed mean reversion patterns, however, centralization and density showed a slight increase from 2013 to 2014 (Centralization of A part from 52.78 to 36.96, B part from 20.56 to 32.20, C part from 34.40 to 37.24; Density of A part from 0.122 to 0.123, B part from 0.111 to 0.121, C part from 0.109 to 0.121). The individual in-degree centrality is significantly correlated with self-directed learning and the correlation coefficient increased during the year (r=.274 in 2013, r=.356 in 2014, p<.001). Conclusion: Students share information more interactively during the year and the more they share the higher the scores of self-directed learning.

The Network Structural Characteristic of Social Welfare Organizations - Focused on the Social Welfare Organizations in Busan - (사회복지시설 네트워크 구조적 특성 - 부산 사회복지 개별기관의 네트워크 활동을 중심으로 -)

  • Kim, Kyeo-Jeung
    • The Journal of the Korea Contents Association
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    • v.9 no.6
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    • pp.309-324
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    • 2009
  • The purpose of this study, decision factors about network characteristics among Social Welfare service organizations and individuals are defined to obtain proper empirical bases for building systematic human service network in the local community bases. As results of analysis, Firstly The order of density is shown as follows the information exchange, the client refer, the resource exchange. Secondly The result about the analysis whether the level factor of the organizational members and organizations affect positively is summarized as follows.it is shown that the number of meeting, organizational type, the prior experience of networking affect positively.

Predicting the Performance of Recommender Systems through Social Network Analysis and Artificial Neural Network (사회연결망분석과 인공신경망을 이용한 추천시스템 성능 예측)

  • Cho, Yoon-Ho;Kim, In-Hwan
    • Journal of Intelligence and Information Systems
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    • v.16 no.4
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    • pp.159-172
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    • 2010
  • The recommender system is one of the possible solutions to assist customers in finding the items they would like to purchase. To date, a variety of recommendation techniques have been developed. One of the most successful recommendation techniques is Collaborative Filtering (CF) that has been used in a number of different applications such as recommending Web pages, movies, music, articles and products. CF identifies customers whose tastes are similar to those of a given customer, and recommends items those customers have liked in the past. Numerous CF algorithms have been developed to increase the performance of recommender systems. Broadly, there are memory-based CF algorithms, model-based CF algorithms, and hybrid CF algorithms which combine CF with content-based techniques or other recommender systems. While many researchers have focused their efforts in improving CF performance, the theoretical justification of CF algorithms is lacking. That is, we do not know many things about how CF is done. Furthermore, the relative performances of CF algorithms are known to be domain and data dependent. It is very time-consuming and expensive to implement and launce a CF recommender system, and also the system unsuited for the given domain provides customers with poor quality recommendations that make them easily annoyed. Therefore, predicting the performances of CF algorithms in advance is practically important and needed. In this study, we propose an efficient approach to predict the performance of CF. Social Network Analysis (SNA) and Artificial Neural Network (ANN) are applied to develop our prediction model. CF can be modeled as a social network in which customers are nodes and purchase relationships between customers are links. SNA facilitates an exploration of the topological properties of the network structure that are implicit in data for CF recommendations. An ANN model is developed through an analysis of network topology, such as network density, inclusiveness, clustering coefficient, network centralization, and Krackhardt's efficiency. While network density, expressed as a proportion of the maximum possible number of links, captures the density of the whole network, the clustering coefficient captures the degree to which the overall network contains localized pockets of dense connectivity. Inclusiveness refers to the number of nodes which are included within the various connected parts of the social network. Centralization reflects the extent to which connections are concentrated in a small number of nodes rather than distributed equally among all nodes. Krackhardt's efficiency characterizes how dense the social network is beyond that barely needed to keep the social group even indirectly connected to one another. We use these social network measures as input variables of the ANN model. As an output variable, we use the recommendation accuracy measured by F1-measure. In order to evaluate the effectiveness of the ANN model, sales transaction data from H department store, one of the well-known department stores in Korea, was used. Total 396 experimental samples were gathered, and we used 40%, 40%, and 20% of them, for training, test, and validation, respectively. The 5-fold cross validation was also conducted to enhance the reliability of our experiments. The input variable measuring process consists of following three steps; analysis of customer similarities, construction of a social network, and analysis of social network patterns. We used Net Miner 3 and UCINET 6.0 for SNA, and Clementine 11.1 for ANN modeling. The experiments reported that the ANN model has 92.61% estimated accuracy and 0.0049 RMSE. Thus, we can know that our prediction model helps decide whether CF is useful for a given application with certain data characteristics.