• Journal of The Korean Association of Information Education
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• v.17 no.4
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• pp.375-382
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• 2013

Collaborative filtering has been most widely used in commercial sites to recommend items based on the history of user preferences for items. The basic idea behind this method is to find similar users whose ratings for items are incorporated to make recommendations for new items. Hence, similarity calculation is most critical in recommendation performance. This paper presents a new similarity measure that takes each rating of a user relatively to his own ratings. Extensive experiments revealed that the proposed measure is more reliable than the classic measures in that it significantly decreases generation of extreme similarity values and its performance improves when consulting neighbors with high similarites only. In particular, the results show that the proposed measure is superior to the classic ones for datasets with large rating scales.

• Journal of the Korean Data and Information Science Society
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• v.27 no.4
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• pp.1027-1033
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• 2016

The purpose of this study is to examine the satisfaction level for military food services as well as to find out influential factors which affect satisfaction. The questionnaire survey was conducted by 111 soldiers. In the satisfaction analysis for military food services, 69.3% of soldiers presented positive response. There are, however, some differences in satisfaction between corporal and private groups as well as corporal and sergeant groups. Overall, the corporal group shows low satisfaction for military food services. To identify influential factors for satisfaction of military food services, we considered various factors: tasty, nutrition, quantity, hygienic conditions, environment, ambient factors, waiting time, presence of desert, menu, and kindness of a cook. Satisfaction analysis shows that main significant factors are tasty and quantity of the food. Thus, tasty and quantity of the food are need to be consistently monitored and improved to increase the satisfaction of military food services.

• Journal of the Korean Data and Information Science Society
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• v.21 no.6
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• pp.1009-1020
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• 2010

In this study, we applied a hierarchial linear model to Anyang city data because students and their schools are hierarchial data structure. As a result, main factors which affect parents' satisfaction to school which their children go to are parents' satisfaction to Anyang city's education policies and areas which their schools located at. We suggest based on the analysis by this hierarchial linear model that if Anyang city make educational policies more efficient and effective in order for students to study in public school without private education and if Anyang city improve environment related with school like those of new cities, parents' satisfaction to school which their children go to will be increased.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.5
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• pp.16-24
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• 2007

Wireless mesh network extends the limited coverage of conventional wireless service from one-hop access point to wider area. It is recognized as an important issue to provide seamless handoff in the wide coverage of wireless mesh network. A long handoff delay may cause high packet loss and disconnection of service, degrading the network performance. The handoff delay is mainly introduced from the channel scanning process obtaining information to make handoff decision and the unnecessary handoffs due to inaccurate handoff decision. In this paper, we propose the handoff algorithm based on one-way trip time (OTT) to expedite the handoff procedure. As compared to the handoff algorithm based on the receiving signal power, the proposed algorithm takes advantage of OTT to obtain the necessary handoff information in a relatively shorter time and reduce the unnecessary handoffs. The performance of proposed algorithm is evaluated through the simulations. It is verified that the proposed handoff algorithm can effectively enhance the handoff accuracy, and therefore reduce the handoff delay and unnecessary handoffs.

• The Journal of the Convergence on Culture Technology
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• v.1 no.1
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• pp.79-85
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• 2015

According to the growing use of the personal GPS in the mobile device recently, the LBS (Local bases service), which processes and refines the GPS information, such as a position-tracking service, a public safety service, a local based information service, has increased steadily. Due to the refraction or reflection of GPS, however, it is impossible to use GPS around or in buildings. Therefore, it is necessary to correct the errors of GPS. We propose the method which corrects the errors of GPS and creates the refined trajectory using intersection region indexing. After analyzing the trajectory, receiving trajectories from many people and identifying the similarity between of trajectories, we will recommend the favorite route and useful information such as restaurant, convenience store, bus station and emergency call service.

• The Journal of Korean Association of Computer Education
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• v.12 no.6
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• pp.69-79
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• 2009

The current user interface (UI) of NEIS school affairs business system is not efficient in conducting the business because of complicated data input forms as well as unharmonious connection between similar items and functional menu. In the paper, the term UI means a comprehensive concept including input/output, input/output related functionality, and menu configuration for users to perform their tasks. The first survey, carried out with one hundred teachers at three elementary schools of Kyeonggi-do, shows that the UI problems of the system are manual inputs, inconvenient menu configuration, disconnection between academic calendar and educational process, complexities of managing attendance report and curriculum evaluation, etc. We have improved the UI design by providing more efficient input method and more systematic menu configuration compared to the current system, and then evaluated the design through the second survey. Evaluation results show that users prefer the proposed UI design especially from the viewpoint of user-friendly input interface and user-oriented view composition.

• Journal of Intelligence and Information Systems
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• v.9 no.3
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• pp.117-135
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• 2003

This study is to propose a procedure solving scale problem of traditional collaborative filtering (CF) approach. The CF approach generally uses some similarity measures like correlation coefficient. So, as the user of the Website increases, the complexity of computation increases exponentially. To solve the scale problem, this study suggests a clustering model-based approach using Self-Organizing Map (SOM) and RFM (Recency, Frequency, Momentary) method. SOM clusters users into some user groups. The preference score of each item in a group is computed using RFM method. The items are sorted and stored in their preference score order. If an active user logins in the system, SOM determines a user group according to the user's characteristics. And the system recommends items to the user using the stored information for the group. If the user evaluates the recommended items, the system determines whether it will be updated or not. Experimental results applied to MovieLens dataset show that the proposed method outperforms than the traditional CF method comparatively in the recommendation performance and the computation complexity.

• KIPS Transactions on Computer and Communication Systems
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• v.1 no.2
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• pp.109-118
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• 2012

As a result of the prevalence of smartphone, various mobile services became faster by LTE networks. Because many mobile devices are used more wireless services, heavy signaling traffic for authentication could be generated. Authentication is an important factor in wireless networks to identify devices; it is the start of wireless networks. This paper analyzes previous patterns for more effective authentication in accessing of another external networks. We propose a fast authentication scheme for minimizing of signaling cost between the authentication server and external networks. And we calculate the rate of authentication occurrence in LTE networks using mathematical modeling as well as the change of signaling cost for authentication in various network environments. Finally, we calculate the optimized number of authentication data and show the effectiveness for authentication signaling costs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.5988-5994
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• 2014

This study examined the effects of dubbing on the ticket sales of foreign animation movies put on the screen in Korea in the context of 'Skopos Theory'. The ticket power of animation increased when dubbing was chosen as the translation strategy. Moreover, the effects were greater when the animation was in the peak seasons, classified as non-restricted, and made in non-US countries. The ticket power was also found to be greater when celebrities joined in the dubbing. This finding was consistent with the 'Skopos Theory', which implied that dubbing is superior to captioning for audience understanding and audience attraction. This study confirmed empirically the positive effects of dubbing on the performance of foreign animation movies, which is the contribution to the literature that has been limited on case studies. These results also suggest that a dubbing strategy should be consistent with its target audience.

• Journal of the Korean Society for Library and Information Science
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• v.49 no.3
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• pp.351-370
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• 2015

This study aims to look at overall adolescents' perceptions of library and reveal the relevance of search engine sources and library sources compared each elements of them and find out any related issues of perceptions of library and information use of them. The data for this study were collected through survey and analyzed descriptive statistics and correlation analysis using the data. The result shows the population users preferred search engine over library as their information search tool, and they used library as primarily a source of information for printed materials such as books and most of them don't use the library often. Also the result shows the population users tend to select information when it is easy to get and fast to access. Correlation analysis such as ${\chi}^2$ and Spearman were implemented and the result of the correlation shows that many factors of this study covered-such as comparison of information sources- have significant differences each other.