• Journal of Communications and Networks
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• v.15 no.2
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• pp.228-239
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• 2013

Peer-to-peer (P2P) systems have proved the most effective and popular file sharing applications in recent years. Previous studies mainly focused on equal service and differentiated service strategies when peers have no initial data before their downloads. For an upload-constrained P2P file sharing system, we model both the equal service process and the differentiated service process when the initial data distribution of peers satisfies some special conditions. Moreover, we show how to minimize the time required to distribute the file to any number of peers. The proposed fluid-based models can reveal the intrinsic relations among the initial data amount, the peer set size, and the minimum last finish time. The closed-form expressions derived from the extended models can closely approximate chunk-based models and systems, especially for relatively large files. As an application of the extended models, we show how to provide differentiated service efficiently to multiple peer sets. Since no limits are imposed on the upload bandwidth of peers or the size of each peer set, we believe that our analytic process and the results achieved can provide not only fundamental insights into bandwidth allocation and data scheduling but also a helpful reference for both improving system performance and building an effective incentive mechanism for P2P file sharing systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.7
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• pp.1447-1454
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• 2012

Recently P2P is the most popular network service on Internet and is applied various areas such as streaming, file sharing and software distribution, but there are many security threats depending on vulnerabilities by P2P network environments. Conceptually P2P network is a overlay network based on Internet, and it has security concerns of itself as well as those of Internet environments. In this paper, we analyze the vulnerabilities and threats for domestic P2P services through various experiments and describe their risk analysis. We expect that this work contributes to new domestic P2P services in consideration of service qualities and security vulnerabilities.

• Journal of information and communication convergence engineering
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• v.8 no.3
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• pp.295-300
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• 2010

Recent researches of network structure are moving to high-level networks because there are already many research results of low-level network. Especially, current network services has been changed to the multimedia service using multicast routing such as IPTV(Internet Protocol Television) service. And then previous multicast services were provider oriented. So previous multicast structures were organized server/client model. But future multicast services will make user oriented services. Therefore there will be many service providers in the future. At this point, we study P2P network for supporting multi provider. So we research load balancing and contents lookup protocols in P2P network. In this paper, we propose network protocol and system based on super peer P2P for load balancing and efficiently service search. And we considered mobile environment for mobile IPTV.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1640-1646
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• 2004

In this study, we propose the multiple VoIP service networks for P2P network environments based on portable internet. We found that voiceservice using portable internet is possible for real time services. After we designe the multiple VoIP service networks for P2P network environments based on portable internet, evaluate the performances. from the performance evaluations, we found satisfactory results and so we can expect the possibility of the portable internet services.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.8
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• pp.1691-1695
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• 2005

Mobile P2P Service can compose free network from one client to another without central server function. Diversified Information & Data are able to be transmitted among peer to peer based upon extended mobile concept. In this paper Mobile P2P Service is applied to the program which gathering, sharing, analysis agricultural information and the natural disasters Information We desire to authenticate request about service to user who is administered between each user to limit connection. Wish to admit authentication mechanism to mechanism that can do information sharing suety in P2P environment to solve this in this treatise and design authentication mechanism.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.3
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• pp.81-86
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• 2014

According to the development of streaming services with P2P and mobile network technologies, researches to enhance the service quality in mobile environment have been proposed. However, streaming services considering high-speed mobile environment and characteristics of heterogenous terminals have been hindered from being provided with the required quality from user because of bandwidth congestion between selfish peers of existing P2P system. It is also prone to long delay and loss in accordance with the repeated traffic amounts because there are no optimized solution for traffic localization. The structure to enhance peer contribution for service differentiation and peer selection with clustering scheme with location information of terminal can satisfy both users and service providers with service quality and efficiency. In this paper, we propose an incentive mechanism and resource distribution scheme with user contribution and traffic cost information based on user location, which make mobile users increase the satisfaction of service quality in LTE environments.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.5
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• pp.538-544
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• 2005

The service supporting structure for users in ubiquitous computing environment requires technology that divides efficiently resources shared around users according to users context. So, needs research that analyze service items and resources that is offered according to users context information and divide adaptively necessary service and resources. Therefore, in this paper we proposes an intelligent P2P mobile agent that recognizes users context using portable mobile devices and is available for intelligent service by sharing serviced item according to users' context. The proposed structure removes monopoly for specific resources, and supports effective users context-awareness and service.

• Korean Journal of Adult Nursing
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• v.21 no.1
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• pp.77-85
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• 2009

Purpose: This study aimed to identify the difference of sexual knowledge, attitudes, and behavior of college students who fulfilled military service and those who did not, for providing basic data for developing nursing interventions for the college students. Methods: This study used a descriptive research design. The subjects of this study were 3,741 male college students. Data were collected through personal interviews using questionnaires from November to December 2007. The sexual knowledge, attitudes, and behavior measurement tool was used. The collected data were analyzed by descriptive statistics, t-test and chi-square test. Results: The major findings of this study were as follows: 1) There was a statistically significant difference in sexual knowledge of contraception / abortion(p = .002, t = 3.16), venereal disease(p = .006, t = .2.73), sexual attitude of sexual behavior(p = .002; t = 3.13) and sexual double think(p = .047, t = 1.98) according to military service 2) There was a statistically significant difference in sexual behavior experience frequency of 9 items(friendship with opposite sex, kiss / embracing, petting, porno magazine / porno video contact, masturbation, sexual intercourse via anus, sexual intercourse via mouth, cause pregnancy, cause abortion: p < .000, $x^2$ = 39.47; p < .000, $x^2$ = 55.88; p < .000, $x^2$ = 46.76; p = .034, $x^2$ = 6.77; p = .017, $x^2$ = 12.05; p = .003, $x^2$ = 14.24; p < .000, $x^2$ = 47.70; p < .000, $x^2$ = 23.86; p < .000, $x^2$ = 21.84) respectively according to military service. Conclusion: The results of this study indicate that sexual knowledge, attitudes and behavior differ before and after the experience of military service, so further study for detecting military sex culture character effecting difference in sex knowledge, attitudes and behavior is needed.

• The Journal of Korean Academic Society of Nursing Education
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• v.9 no.1
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• pp.103-114
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• 2003

The purpose of this study is to test the motivation, attitude of voluntary service and self-esteem of college students. Therefore it can give the fundamental data of the institutionalization plan and to find the activative methods of voluntary system. This study is based on the questionaire, that was consisted of motivation, attitude of voluntary service and self-esteem. For this study, 223 college students were answered. The data was collected from 10th to 30th September 2002. The results of this study are as follows : 1. $\cdot$The mean score on the motivations scale of voluntary service was $3.221{\pm}0.42$. $\cdot$The mean score on the attitudes scale of voluntary service was $3.28{\pm}0.49$. $\cdot$The mean score on the self-esteem was $2.56{\pm}0.46$. 2. There were significant differences between voluntary service was self motivated(F= 11.12, p= 0.000), the students who will participate very active in voluntary service aftergraduation(F= 11.12, p= 0.000), and the motivations of voluntary service. 3. There were significant differences between the students who will participate very active in voluntary service after graduation (F= 8.23, p= 0.000) and the attitudes of voluntary service. 4. There were significant differences between voluntary service was self motivated (F=4.69, p= 0.004), the students who will participate very active in voluntary service after graduation(F=2.49, p=0.045), the parents who have the experience of voluntary service(F= 5.03, p= 0.026), the students who have the experience of voluntary service before college entrance. 5. There was positively significant correlation between the motivations of voluntary service and the attitudes (r= .693, P=0.01), the attitudes and self-esteem (r= .326, p=0.01), and the motivations of voluntary service and self-esteem (r= .305, p=0.01).

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.1
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• pp.21-28
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• 2009

In this paper, we consider the Femtocell based enterprise wireless network using 2G/3G/4G cellular network technologies. And, we apply the open network service API which enable an easy development of ISP or enterprise services to P2P enterprise services. Based on the proposed scheme, enterprise services can be always connected at anywhere and anytime via heterogeneous devices. By using a qualitative analysis, we evaluate the performance of the proposed scheme and compare with that of the famous P2P service - Skype. Results show that the proposed scheme requests smaller servers and flows with enhanced service quality.