• The Journal of Korean Association of Computer Education
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• v.3 no.2
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• pp.67-75
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• 2000

Due to the advantages of Internet, many teachers use Internet as an educational tool and due to the computerized works in schools, the usages of the Internet increase. However, because of the openness of the Internet, the sensitive data of an organization are exposed to outsiders and the Internet-based working has some problems such as the corruptions of instructional data or on-line assessment results. The need for protecting a school network from outsiders increases but the school networks with firewalls rarely exist. In this paper, in order to solve the security problem of a school network, we construct a hybrid firewall for school networks. In addition, we implement a graphical user interface for teachers to set up the access control rules of a hybrid firewall easily. The interface also provides the facilities such as log analysis, a real-time monitor for network traffics, and the statistic on traffics.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.7
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• pp.693-701
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• 2002

In this paper, we analyze the coverage of asynchronous IMT(International Mobile Telecommunication)-2000 reverse link with a MUD(Multi-User Detector) system. The MUD system is utilized to increase the coverage of reverse link. Also we have considered a propagation loss model and an interference effect. Because it is very difficult that we have calculated the interference accurately, so a fractional cell loading factor(F) is used in this paper. We make use of a MUD efficiency($\beta$) to analyze the performance; this efficiency is presented the MAI of reduction. A simulation utilizes Hata's model, we calculated the coverage according to voice and data services. In this paper, we have assumed that the frequency of carrier has 800 MHz or 1.9 GHz, and a bandwidth is decided 3.84 MHz. We have predicted the performance of actual system by the analysis of capacity and coverage.

• Journal of Information Science Theory and Practice
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• v.7 no.3
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• pp.6-20
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• 2019

Learning analytics, or educational data mining, is an emerging field that applies data mining methods and tools for the exploitation of data coming from educational environments. Learning management systems, like Moodle, offer large amounts of data concerning students' activity, performance, behavior, and interaction with their peers and their tutors. The analysis of these data can be elaborated to make decisions that will assist stakeholders (students, faculty, and administration) to elevate the learning process in higher education. In this work, the power of Excel is exploited to analyze data in Moodle, utilizing an e-learning course developed for enhancing the information computer technology skills of school teachers in primary and secondary education in Greece. Moodle log files are appropriately manipulated in order to trace daily and weekly activity of the learners concerning distribution of access to resources, forum participation, and quizzes and assignments submission. Learners' activity was visualized for every hour of the day and for every day of the week. The visualization of access to every activity or resource during the course is also obtained. In this fashion teachers can schedule online synchronous lectures or discussions more effectively in order to maximize the learners' participation. Results depict the interest of learners for each structural component, their dedication to the course, their participation in the fora, and how it affects the submission of quizzes and assignments. Instructional designers may take advice and redesign the course according to the popularity of the educational material and learners' dedication. Moreover, the final grade of the learners is predicted according to their previous grades using multiple linear regression and sensitivity analysis. These outcomes can be suitably exploited in order for instructors to improve the design of their courses, faculty to alter their educational methodology, and administration to make decisions that will improve the educational services provided.

• Convergence Security Journal
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• v.18 no.5_1
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• pp.45-51
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• 2018

As data utilization and importance becomes important, data-related accidents and damages are gradually increasing. Especially, insider threats are the most harmful threats. And these insider threats are difficult to detect by traditional security systems, so rule-based abnormal behavior detection method has been widely used. However, it has a lack of adapting flexibly to changes in new attacks and new environments. Therefore, in this paper, we propose an adaptive anomaly movement detection framework based on a statistical Markov model to detect insider threats in advance. This is designed to minimize false positive rate and false negative rate by adopting environment factors that directly influence the behavior, and learning data based on statistical Markov model. In the experimentation, the framework shows good performance with a high F2-score of 0.92 and suspicious behavior detection, which seen as a normal behavior usually. It is also extendable to detect various types of suspicious activities by applying multiple modeling algorithms based on statistical learning and environment factors.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.5
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• pp.813-826
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• 2023

Organization members often use the Internet for non-work purposes during work hours, which is called cyberloafing. Certain types of cyberloafing (e.g., webhard, adult, and gambling sites access) can be a major cause of malware infection, which can ultimately generate significant damages to organizations. It therefore is important to examine the relationship between cyberloafing and cybersecurity risks of organizations. We analyzed log data from an internet filtering system of a financial institute and found that the more employees access to blacklist sites, the higher the possibility of malicious code infection. In other words, cyberloafing increases cybersecurity risks of organizations. We suggest that organizations need to monitor and control their members' internet use in an appropriate way.

• Journal of the Korea Society of Computer and Information
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• v.20 no.5
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• pp.1-12
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• 2015

NAND flash memory has being used for storage systems widely, because it has good features which are low-price, low-power and fast access speed. However, NAND flash memory has an in-place update problem, and therefore it needs FTL(flash translation layer) to run for applications based on hard disk storage. The FTL includes complex functions, such as address mapping, garbage collection, wear leveling and so on. Futhermore, implementation of the FTL on low-power embedded systems is difficult due to its memory requirements and operation overhead. Accordingly, many index data structures for NAND flash memory have being studied for the embedded systems. Overall performances of the index data structures are enhanced by a decreasing of page write counts, whereas it has increased page read counts, as a side effect. Therefore, we propose an index management method using a page mapping log table in $B^+$-Tree based on NAND flash memory to decrease page write counts and not to increase page read counts. The page mapping log table registers page address information of changed index node and then it is exploited when retrieving records. In our experiment, the proposed method reduces the page read counts about 61% at maximum and the page write counts about 31% at maximum, compared to the related studies of index data structures.

• The Journal of the Korea Contents Association
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• v.5 no.4
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• pp.141-149
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• 2005

The paper's suggestion is Web based Tele-Medicine System will be open to public, low-budget featuring high quality of extensive medical services. It will keep a log of personal medical history to allow doctors to share information on patients and their families. This will result in the reduction of erroneous diagnosis and ensure successful e-business. On top of this, the new system will provide a solution for membership (client) management. It will combine online and offline medical services and be available 24 hours a day to anywhere users have Internet access, setting itself apart from the existing distance medical services system. Specially, The paper's suggestion is sharing medical treatment information between family members is suggested. This approach makes possible understanding physical constitution and environment between family members, and can result in bringing a faster treatment effect if some family member suffers from a similar disease.

• Journal of Convergence Society for SMB
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• v.6 no.4
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• pp.31-36
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• 2016

User authentication is the first step to network security. There are lots of authentication types, and more than one authentication method works together for user's authentication in the network. Except for biometric authentication, most authentication methods can be copied, or someone else can adopt and abuse someone else's credential method. Thus, more than one authentication method must be used for user authentication. However, more credential makes system degrade and inefficient as they log on the system. Therefore, without tradeoff performance with efficiency, this research proposed user's behavior based authentication for secure communication, and it will improve to establish a secure and efficient communication.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.556-560
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• 2002

In this paper, we propose a remote controller for robot manipulator using local area network(LAN) and internet. To do this, we develope a server-client system as used in the network field. The client system is in any computer in remote place for the user to log-in the server and manage the remote factory. the server system is a computer which controls the manipulator and waits for a access from client. The server system consists of several control algorithms which is needed to drive the manipulator and networking system to transfer images that shows states of the work place, and to receive a Tmp data to run the manipulator The client system consists of 3D(dimension) graphic user interface for teaching and off-line task like simulation, external hardware interface which makes it easier for the user to teach. Using this server-client system, the user who is on remote place can edit the work schedule of manipulator, then run the machine after it is transferred and monitor the results of the task.

• Journal of the Korea Computer Industry Society
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• v.4 no.10
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• pp.621-630
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• 2003

Web logs are the information recorded by a web server when users access the web sites, and due to a speedy rising of internet usage, the worth of their practical use has become increasingly important. Analyzing such logs can use to determine the patterns representing users' navigational behavior in a Web site and restructure a Web site to create a more effective organizational presence. For these applications, the generally used key methods in many studies are association rules and sequential patterns based by Apriori algorithms, which are widely used to extract correlation among patterns. But Apriori inhere inefficiency in computing cost when applied to large databases. In this paper, we develop a new algorithm for mining interesting patterns which is faster than Apriori algorithm and recommendation agents which could provide a system manager with valuable information that are accessed sequentially by many users.