• Korean Security Journal
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• no.42
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• pp.7-36
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• 2015

This study aims at analyzing difference of social Security network, Community unity and local government trust according to socio-demographical features, exploring the relation of social Security network, Community unity and local government trust according to socio-demographical features, presenting results between each variable as a model and verifying the property of mutual ones. This study sampled general citizens in Gwangju for about 15 days Aug. 15 through Aug. 30, 2014, distributed total 450 copies using cluster random sampling, gathered 438 persons, 412 persons of whom were used for analysis. This study verified the validity and credibility of the questionnaire through an experts' meeting, preliminary test, factor analysis and credibility analysis. The credibility of questionnaire was ${\alpha}=.809{\sim}{\alpha}=.890$. The inout data were analyzed by study purpose using SPSSWIN 18.0, as statistical techniques, factor analysis, credibility analysis, correlation analysis, independent sample t verification, ANOVA, multi-regression analysis, path analysis etc. were used. the findings obtained through the above study methods are as follows. First, building a social Security network has an effect on Community institution. That is, the more activated a, the higher awareness on institution. the more activated street CCTV facilities, anti-crime design, local government Security education, the higher the stability. Second, building a social Security network has an effect on trust of local government. That is, the activated local autonomous anti-crime activity, anti-crime design. local government's Security education, police public oder service, the more increased trust of policy, service management, busines performance. Third, Community unity has an effect on trust of local government. That is, the better Community institution is achieved, the higher trust of policy. Also the stabler Community institution, the higher trust of business performance. Fourth, building a social Security network has a direct or indirect effect on Community unity and local government trust. That is, social Security network has a direct effect on trust of local government, but it has a higher effect through Community unity of parameter. Such results showed that Community unity in Gwangju Region is an important factor, which means it is an important variable mediating building a social Security network and trust of local government. To win trust of local residents, we need to prepare for various cultural events and active communication space and build a social Security network for uniting them.

• Journal of Intelligence and Information Systems
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• v.23 no.2
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• pp.19-38
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• 2017

Collaborative filtering (CF) algorithm has been popularly used for implementing recommender systems. Until now, there have been many prior studies to improve the accuracy of CF. Among them, some recent studies adopt 'hybrid recommendation approach', which enhances the performance of conventional CF by using additional information. In this research, we propose a new hybrid recommender system which fuses CF and the results from the social network analysis on trust and distrust relationship networks among users to enhance prediction accuracy. The proposed algorithm of our study is based on memory-based CF. But, when calculating the similarity between users in CF, our proposed algorithm considers not only the correlation of the users' numeric rating patterns, but also the users' in-degree centrality values derived from trust and distrust relationship networks. In specific, it is designed to amplify the similarity between a target user and his or her neighbor when the neighbor has higher in-degree centrality in the trust relationship network. Also, it attenuates the similarity between a target user and his or her neighbor when the neighbor has higher in-degree centrality in the distrust relationship network. Our proposed algorithm considers four (4) types of user relationships - direct trust, indirect trust, direct distrust, and indirect distrust - in total. And, it uses four adjusting coefficients, which adjusts the level of amplification / attenuation for in-degree centrality values derived from direct / indirect trust and distrust relationship networks. To determine optimal adjusting coefficients, genetic algorithms (GA) has been adopted. Under this background, we named our proposed algorithm as SNACF-GA (Social Network Analysis - based CF using GA). To validate the performance of the SNACF-GA, we used a real-world data set which is called 'Extended Epinions dataset' provided by 'trustlet.org'. It is the data set contains user responses (rating scores and reviews) after purchasing specific items (e.g. car, movie, music, book) as well as trust / distrust relationship information indicating whom to trust or distrust between users. The experimental system was basically developed using Microsoft Visual Basic for Applications (VBA), but we also used UCINET 6 for calculating the in-degree centrality of trust / distrust relationship networks. In addition, we used Palisade Software's Evolver, which is a commercial software implements genetic algorithm. To examine the effectiveness of our proposed system more precisely, we adopted two comparison models. The first comparison model is conventional CF. It only uses users' explicit numeric ratings when calculating the similarities between users. That is, it does not consider trust / distrust relationship between users at all. The second comparison model is SNACF (Social Network Analysis - based CF). SNACF differs from the proposed algorithm SNACF-GA in that it considers only direct trust / distrust relationships. It also does not use GA optimization. The performances of the proposed algorithm and comparison models were evaluated by using average MAE (mean absolute error). Experimental result showed that the optimal adjusting coefficients for direct trust, indirect trust, direct distrust, indirect distrust were 0, 1.4287, 1.5, 0.4615 each. This implies that distrust relationships between users are more important than trust ones in recommender systems. From the perspective of recommendation accuracy, SNACF-GA (Avg. MAE = 0.111943), the proposed algorithm which reflects both direct and indirect trust / distrust relationships information, was found to greatly outperform a conventional CF (Avg. MAE = 0.112638). Also, the algorithm showed better recommendation accuracy than the SNACF (Avg. MAE = 0.112209). To confirm whether these differences are statistically significant or not, we applied paired samples t-test. The results from the paired samples t-test presented that the difference between SNACF-GA and conventional CF was statistical significant at the 1% significance level, and the difference between SNACF-GA and SNACF was statistical significant at the 5%. Our study found that the trust/distrust relationship can be important information for improving performance of recommendation algorithms. Especially, distrust relationship information was found to have a greater impact on the performance improvement of CF. This implies that we need to have more attention on distrust (negative) relationships rather than trust (positive) ones when tracking and managing social relationships between users.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.12
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• pp.1898-1903
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• 2021

Recently, the need to be wary of internal access such as internal access as well as external attackers' access to work has increased due to network expansion, cloud infrastructure expansion, and changes in working patterns due to COVID-19 situations. For this reason, a new network security model called Zero Trust is drawing attention. Zero Trust has a key principle that a trusted network does not exist, and in order to be allowed access, it must be authenticated first, and data resources can only be accessed by authenticated users and authenticated devices. In this paper, we will explain these zero trust and zero trust architectures and examine new security application strategies applicable to various companies using zero trust and the process of building a new security system based on the zero trust architecture model.

• Journal of the Korean housing association
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• v.26 no.3
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• pp.99-108
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• 2015

The purpose of this study was to determine the relationship between subjective happiness and social capital. The data for the analysis were collected via the questionnaire survey method, from October 29 to November 10, 2013. The sample consisted of 338 residents, living in Seoul and Gyeonggi-Do province. Social capital is composed of the social network, social trust and social norms. The social network is composed of the satisfaction of one's social relations, and the degree of social interaction. Social trust is composed of the trust in ones's neighbors and the local community. Social norms are composed of reciprocity, participation and a sense of belonging and solidarity. The findings of this study were as follows: 1) The average for subjective happiness was 3.82 points, over neutral. In particular, the subjective happiness of people over 50 years old was highest. 2) The social network, social trust, and social norms were related to the subjective happiness.

• Knowledge Management Research
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• v.14 no.5
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• pp.101-120
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• 2013

The effective management of knowledge has become one of the critical success factors in current organizations. In spite of the extensive use of Knowledge Management System (KMS), useful information and knowledge resources are still transmitted through personal networks among people in organizations. Thus, social network theory which focuses on social relationships in organization can be a fruitful theoretical resource for enhancing Knowledge Management (KM) performances. In this study, we investigate the effects of intra-team network characteristics (i.e., group density and degree of centralization) and external boundary spanning activities on knowledge management performances of a team. We also acknowledge that all group members do not necessarily agree on the team goal and actively disseminate useful information and knowledge. Drawing on the political perspective on KM which emphasizes the role of trust among group members, we examine the mediating effects of team trust between internal/external network characteristics and KM performances. From the data of 220 teams in financial companies in Korea, we found that: (1) group density had positive effects on KM performances (i.e., knowledge creation, sharing, and use). (2) However, centralization was not significantly associated with KM performances. (3) Team trust was found to be an important factor mediating the relationship between intra-team network characteristics, boundary spanning activities, and KM performances. Based on these results, we discuss and suggest possible implications of the findings when designing and implementing KM practices.

• Journal of Communications and Networks
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• v.18 no.1
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• pp.105-111
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• 2016

Trust models in the literature of MANETs commonly assume that packets have different security requirements. Before a node forwards a packet, if the recipient's trust level does not meet the packet's requirement level, then the recipient must perform certain security association procedures, such as re-authentication. We present in this paper an analysis of the epidemic broadcast delay in such context. The network, mobility and trust models presented in this paper are quite generic and allow us to obtain the delay component induced only by the security associations along a path. Numerical results obtained by simulations also confirm the accuracy of the analysis. In particular, we can observe from both simulation's and analysis results that, for large and sparsely connected networks, the delay caused by security associations is very small compared to the total delay of a packet. This also means that parameters like network density and nodes' velocity, rather than any trust model parameter, have more impact on the overall delay.

• KIPS Transactions on Software and Data Engineering
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• v.2 no.11
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• pp.747-756
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• 2013

It is important to reduce unnecessary overhead in sensor network using battery. In addition encryption is important because of necessity of security. Since unavoidable overhead occurs in case of encryption, security and overhead are in trade-off condition. In this paper, we use a concept called trust to reduce the encryption overhead. We reduce overhead by controlling encryption key sizes while maintaining the security level where high and low trust nodes are mixed. We simulated and compared normal encryption and trust value based encryption. As a result, the latter has lower execution time and overhead. If we define a standard of trust levels considering purpose and circumstances of real network, we can use constrained resources efficiently in sensor network.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.199-201
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• 2013

In a construction project in which cooperation among project members gets its importance, trust among construction site members should be foundation to enhance team spirit and achievement. This study analyzes the trust network among staff by using social network analysis (SNA) theory for organizations in apartment complex construction sites in Korea. The analysis illustrates higher level of trust for those positioning in the higher positions in hierarchy and having greater experiences. It might be attributable to own features of construction works where skills are acquired by site experience.

• Informatization Policy
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• v.18 no.2
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• pp.49-71
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• 2011

This study aims at finding what factors influence trust in e-government and how trust in e-government and satisfaction with e-government services affect trust in government. Despite of the importance of trust in e-government, there has not been sufficient research. Giving light on the factors of affecting trust in e-government is of academic significance. Therefore, the purpose of this study is to explore the nature, driving forces and consequences of citizens'trust in e-government and in government. The empirical results indicated that temporal embeddedness, network embeddedness, information provision quality, information security quality and e-participation quality affect satisfaction with e-government services and trust in e-government. Also, satisfaction with e-government services and trust in e-government influence trust in government, and satisfaction with e-government services affect trust in e-government.

• International Journal of Computer Science & Network Security
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• v.21 no.12spc
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• pp.565-569
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• 2021

The rapid growth and development of ICT (Information and Communication Technology) and internet services has boosted the adoption of Mobile Government services all around the globe. There is a huge increase in the adoption of government services during COVID-19 pandemic. Existing Mobile Government (MG) solutions are not trustworthy and secure. This paper provides secure and trustworthy solution for mobile government, proposes a centralized smart governance architecture which is based on trust manager. Our proposed work has Wireless Bridge Certifying Authority (WBCA) and Wireless Public Key Infrastructure (WPKI) thereby ensuring security and privacy. Our proposed work ensures trust with WBCA as WBCA acts as a Trust Manager (TM). Proposed protocol has less computational cost and energy cost