• Journal of the Korea Society of Computer and Information
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• v.15 no.3
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• pp.55-63
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• 2010

On Handoff, existing AP search has chosen one of various APs according to signal strength. However IEEE 802.11 uses Medium Access method with CSMA/CA(Carrier Sensing Multiple Access /Collision Avoidance) that competes to obtain a channel by sharing common medium. For that reason, network performance is heavily affected by the number of nodes and network congestion aside from signal strength. Consequently, in this paper we propose the method that choose one AP which ensures more improved network performance and set up a link, reflecting AP network information in Handoff area, on Handoff in the process of AP selection. We also demonstrate through simulation that it gets maximum performance even in the wireless network which many users concurrently access to, and it has considerable effects on aspects of resources and network management by distribution of users.

• KIPS Transactions on Software and Data Engineering
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• v.3 no.2
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• pp.101-108
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• 2014

As browsing and sharing multimedia contents through various social network services have become very common these days. there has been a rising demand for effectively provide appropriate multimedia contents to users depending on their interest and characteristics. Especially, considering the enormous volume of multimedia contents created daily, user satisfaction heavily depends on effective selection of appropriate multimedia contents. For instance, if the acquisition of contents is based on friends or related people, then it is usually considered to be more trustworthy. Facebook page is one of the social spaces where people can obtain various information of interest. Still, users have difficulty in finding proper information because Facebook generates tremendous amount of data daily. In this paper, we proposed a scheme to extract and select Facebook page contents effectively. In our proposed scheme, users are grouped based on mutual intimacy and Facebook pages of interest are selected based on the ranking of importance. We show the performance of our scheme through experiments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12A
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• pp.1111-1119
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• 2005

A single fiber cut can potentially influence a total of 1.6 Tbps of traffic and is surprisingly frequent and results in significant loss of traffic. The survivability as we as the resource utilization of the connection in optical networks is important. Existing protection mechanisms to rapidly recover the failures allocate the backup path just SRLG-disjointed with working path. Those did not consider the unbalanced resource share of backup paths. The backup paths can be centralized on the specific link so that the idle resource is not used. As a result, as those do not efficiently use the resource the whole resource utilization is not so good. So we propose the mechanism to enhance the resources utilization as settling down the unbalanced resource share. Our purpose is to improve the link utilization as distributing the maximum link load.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.2A
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• pp.83-94
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• 2012

Various wireless communication devices or network such as WRAN and WLAN will coexist in the TVWS(TV White Space). Because of this coexistence, the wireless devices which use the TVWS have to avoid interfering to not only licensed TV receiver and wireless microphone but also homogeneous or heterogeneous TVBD(TV Band Device)s. In this paper, we propose two frequency sharing methods for the coexistence of WLAN and WRAN in terms of interference reduction and throughput enhancement in both homogeneous and heterogeneous networks. One is the WRAN spectrum etiquette to provide more wide bandwidth for WLAN users and the other is the WLAN frequency selection methods to improve the throughput performance. The simulation results have confirmed the throughput improvement of the proposed methods. Moreover, the proposed methods is also applicable to improve the throughput performance and reduce interference of similar systems working in a cognitive manner.

• Journal of KIISE:Information Networking
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• v.30 no.3
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• pp.424-436
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• 2003

In this paper, we propose the Centroid-based Backbone Core Tree(CBCT) generation algorithm for the shared tree-based IP multicasting. The proposed algorithm is based on the Core Based Tree(CBT) protocol. Despite the advantages over the source-based trees in terms of scalability, the CBT protocol still has the following limitations; first, the optimal core router selection is very difficult, and second, the multicast traffic is concentrated near a core router. The Backbone Core Tree(BCT) protocol, as an extension of the CBT protocol has been proposed to overcome these limitations of the CBT Instead of selecting a specific core router for each multicast group, the BCT protocol forms a backbone network of candidate core routers which cooperate with one another to make multicast trees. However, the BCT protocol has not mentioned the way of selecting candidate core routers and how to connect them. The proposed CBCT generation algorithm employs the concepts of the minimum spanning tree and the centroid. For the performance evaluation of the proposed algorithm, we showed the performance comparison results for both of the CBT and CBCT protocols.

• Journal of dental hygiene science
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• v.15 no.1
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• pp.77-82
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• 2015

The purpose of this study was to understand the buying behavior characteristics of the customers. Also, it was intended to provide information to provide companies marketing strategy. The criteria of purchasing toothpaste was to try to understand the impact on satisfaction, recommendation and repurchase Intention. The study was surveyed 248 customers who re-buy the toothpaste in oral care products showroom at university dental hospital. Statistical analysis was performed using PASW Statistics 18.0 and AMOS 18.0 at the 5% significance level. The results were as follows: 'Flavor', 'Price', 'Brand', 'Function', 'Design' of toothpaste and satisfaction showed a positive correlation. Satisfaction and repurchase intention, Recommendation showed a positive correlation. Selection criteria that affect the satisfaction when customers buy toothpaste, 'Function' was the greatest and others became the order of the 'Brand', 'Flavor', 'Price'. Satisfaction affect the recommendation and repurchase Intention. If customers are satisfied with the toothpaste products, showed the Repurchase Intention, have shown opinion that is willing to recommend this product to others. Therefore, dentistry and manufacturers of toothpaste must share a lot of information about toothpaste with customers. Also, information, function, flavor of toothpaste as well as other oral care product, It will be a needed the continuing research and development.

• Korean Educational Research Journal
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• v.38 no.2
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• pp.109-125
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• 2017

The purpose of this study was to examine how group argumentations mediated individual arguments by analyzing physics teachers' group argumentation and individual follow-up written arguments. Five in-service physics teachers participated in this study, two middle school and three high school teachers. The topics of argumentation included physics topics and pedagogy of them. Findings showed that the teachers constructed much more elaborated individual written arguments than group argumentation, which seemed to be resulted from different perceptions of teachers' verbal and written argumentations. Also, in their written arguments the teachers selectively utilized their colleagues' ideas shared during group argumentation. Lastly, teachers' argumentation showed different features between topics of physics and physics pedagogy. These differences were related to their orientations toward argumentation about content knowledge and teaching. These findings shed light on a productive physics teacher professional development in argumentation.

• Journal of the Korean Society for information Management
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• v.28 no.4
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• pp.183-200
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• 2011

This study surveyed editors of 309 gratis open access journals in Korea in order to examine the reason why they decided to open their journals to the public on the Web. Also this study examined their perceptions and attitudes toward open access publishing. The main reasons of open access publishing in Korea were expansion of free use, increasing citation, and international trends regarding open access in their scholarly fields. Also, 65% of all respondents were aware of the concepts of open access, and 75% supported open access. The reasons of supporting open access were sharing of research results with the public, increasing the availability of peer researchers, and enhancing journal reputations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.3
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• pp.249-257
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• 2013

Recently, data traffic is significantly increased by high rate data service. As a result, radio spectrum is considered one of the most scarce and valuable resources for wireless communications. For the solution of this problem, cognitive radio(CR) has been proposed as an efficient means to opportunistic spectrum sharing between primary (licensed) users and cognitive radio users. In this paper, user selection scheme in CR networks is proposed for additional consideration of secondary system. The proposed user selection scheme mitigates interference to primary user by using orthogonal channel vectors while improves performance of secondary system. Simulation results show that the proposed scheme achieves 1.62bps/Hz higher average throughput of whole system than one of the existing scheme.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.1
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• pp.106-112
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• 2007

A new space-time cooperative communication relaying strategy with assistant or management terminals is proposed in multi-hop wireless communication systems. More than one relaying terminals are included in one cooperative group to share the state information such as frame error rate and channel information. Among the cooperative group, the best ones are selected to send bit information using space-time codes. An implementation for the proposed scheme is also presented using a TDMA cooperative protocol. Receive signal to transmit signal ratio($E_r/E_s$) and computer simulation show the strategy outperform the conventional cooperative system.