• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4442-4466
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• 2016

This paper proposes a privacy-preserving aggregation scheme based on the designed P-Gene (PAPG) for sensor networks. The P-Gene is constructed using the designed erasable data-hiding technique. In this P-Gene, each sensory data item may be hidden by the collecting sensor node, thereby protecting the privacy of this data item. Thereafter, the hidden data can be directly reported to the cluster head that aggregates the data. The aggregation result can then be recovered from the hidden data in the cluster head. The designed P-Genes can protect the privacy of each data item without additional data exchange or encryption. Given the flexible generation of the P-Genes, the proposed PAPG scheme adapts to dynamically changing reporting nodes. Apart from its favorable resistance to data loss, the extensive analyses and simulations demonstrate how the PAPG scheme efficiently preserves privacy while consuming less communication and computational overheads.

• Journal of Internet Computing and Services
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• v.10 no.5
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• pp.145-152
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• 2009

Applications such as study guides and adaptive tutoring must rely on a fine grained student model to tailor their interaction with the user. They are useful for Computer Adaptive Testing (CAT), for example, where the test items can be administered in order to maximize the information. I study how to design learner tailoring question process for recommendation. And this process can be applied the CAT and I use the formal language such as CSP in each process development for efficient process design. I use the item difficulty of item response theory for question recommendation process and learner can choice the difficulty step for learning change to control the difficulty of question in next learning. Finally, this method displayed the structural difference to compare between existent and this process.

• Journal of Internet Computing and Services
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• v.11 no.2
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• pp.165-172
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• 2010

In Web-based learning systems, the techniques, as self-regulated learning, self-directed learning, are used to improve the effect of learner's study. These techniques are methods considering learner's study level but to consider the learner's study ability properly, the tailored course for learner should be applied. In this research, the learning system considering learner's study ability was proposed. To decide a learner's study ability, IRT(Item Response Theory) was applied and learning contents and question items were developed and applied by the degree of difficulty.

• Journal of Internet Computing and Services
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• v.10 no.2
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• pp.117-124
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• 2009

SEED game provides distribution of ability, bulky scenario, association system and a item layered. To improve SEED mobile game, we was designed the high degree of freedom as according to player's processing direction and optimization lavel. And also we assigned various event and quest for users.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.9
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• pp.4684-4705
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• 2019

Collaborative filtering recommender systems are vulnerable to shilling attacks in which malicious users may inject biased profiles to promote or demote a particular item being recommended. To tackle this problem, many robust collaborative recommendation methods have been presented. Unfortunately, the robustness of most methods is improved at the expense of prediction accuracy. In this paper, we construct a robust Bayesian probabilistic matrix factorization model for collaborative filtering recommender systems by incorporating the detection of user anomaly rating behaviors. We first detect the anomaly rating behaviors of users by the modified K-means algorithm and target item identification method to generate an indicator matrix of attack users. Then we incorporate the indicator matrix of attack users to construct a robust Bayesian probabilistic matrix factorization model and based on which a robust collaborative recommendation algorithm is devised. The experimental results on the MovieLens and Netflix datasets show that our model can significantly improve the robustness and recommendation accuracy compared with three baseline methods.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.11a
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• pp.191-194
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• 2003

As internet commerce grows, many company has begun to use a CF (Collaborative Filtering) as a Recommender System. To achieve an accuracy of CF, we need to obtain sufficient account of voting scores from customers. Moreover, those scores may not be consistent. To overcome this problem, we propose a new recommendation scheme using binary user-item matrix, which represents whether a user purchases a product instead of using the voting scores. Through the experiment regarding this new scheme, a better accuracy is demonstrated.

• Korean Journal of Child Studies
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• v.28 no.6
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• pp.37-52
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• 2007

This study was planned to develop an Internet Game Addiction Scale for 9- to 12-year-old Korean children. Based on literature review and analysis of counseling cases, the concept of the internet game addiction was defined. Items of the scale were developed and then the content validity of the scale was examined by 20 professionals. Then a preliminary survey of 188 3rd to 6th grade students was made, and the main survey of 699 3rd to 6th grade students throughout Korea. The main results are as follows; [I] Internet Game Addiction Scale consists of 3 factors with 20 items : game-oriented life(6 items), tolerance & mastery loss(7 items), and withdrawal & emotional experience(7 items); [II] appropriateness of item mean and standard deviation was proved, a 3-factor structure confirmed through factorial analysis and cross validation; [III] appropriateness of the scale confirmed through criterion validity and reliability.

• Journal of Korea Multimedia Society
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• v.13 no.1
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• pp.153-160
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• 2010

The main goal of general Online games is that the game user gain a high level character. If you want to grow up your character so fast, you need to have proper items. But sometimes users get items in the game that are not fit for the character. For the reason, game's users exchange these items each other. But such a function that serviced in the game is very restricted. To improve dealing function, it is necessary to support various method in the game such as Internet item dealing sites. By providing various service like as auction system service not the general dealing method, it is convenient for game users to deal with their own items. In this paper, by analyzing both function of internet item dealing site and function of item dealing used some domestic on-line game, we are propose the design method of auction type e-commerce that has the each advantage. Using the our proposed method, users can get information rapidly who want to deal with their own items, and deal with items through various functions.

• Journal of Families and Better Life
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• v.24 no.1 s.79
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• pp.71-82
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• 2006

The purpose of this study was to develop a standardized scale to measure consumers' motivation to purchase based on a self-determination theory. A preliminary 27-item scale was developed through literature review, diary analysis, and FGI. A questionnaire survey was conducted among 1,000consumers on internet using the preliminary scale. Then a series of tests, such as test-retest, item analysis, item-to-total correlation, Cronbach's reliability coefficient, and factor analysis, were conducted using the survey data. The final scale with21 items was constructed in the end. The Purchase Motivation Scale for Consumers consisted of five factors: (1) external motivation, (2) introjected motivation, (3) identified motivation I: self-respect, (4) identified motivation II: pursuit of harmony, and (5) internal motivation.

• Communications for Statistical Applications and Methods
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• v.9 no.2
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• pp.425-434
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• 2002

In this paper, we evaluated the technological forecasting based on questionnaires of experts working in internet-banking industry. We prepared questionnaires on the 13 items. We examined specialties of respondents, relative importance of research contents, expected time of realization, likelihood of conviction on the expected time of realization, and their opinions on the levels of domestic's research and development comparing with advanced standards on each item. And we made various analysis based on data collected from Delphi method.