• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.4
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• pp.1876-1883
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• 2011

The TPM is a hardware chip for making a trusted environment on computing system. We previously need a command authorization process to use principal TPM commands. The command authorization is used to verify an user who knows a usage secret to TPM chip. Since the user uses a simple password to compute usage secret, an attacker can retrieve the password by evasdropping messages between user and TPM chip and applying off-line dictionary attack. In this paper, we simulate the off-line dictionary attack in real PC environment adopted a TPM chip and propose a novel countermeasure to defeat this attack. Our proposed method is very efficient due to its simplicity and adaptability without any modification of TPM command structures.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.4
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• pp.148-159
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• 2005

We propose a technique for finding the worst case response time (WCRT) of a DMA request that is needed in the schedulability analysis of a whole real-time system. The technique consists of three steps. In the first step, we find the worst case bus usage pattern of each CPU task. Then in the second step, we combine the worst case bus usage pattern of CPU tasks to construct the worst case bus usage pattern of the CPU. This second step considers not only the bus requests made by CPU tasks individually but also those due to preemptions among the CPU tasks. finally, in the third step, we use the worst case bus usage pattern of the CPU to derive the WCRT of DMA requests assuming the fixed-priority bus arbitration protocol. Experimental results show that overestimation of the DMA response time by the proposed technique is within $20\%$ for most DMA request sizes and that the percentage overestimation decreases as the DMA request size increases.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.3
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• pp.231-241
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• 2019

Web Usage Mining (WUM) is one part of Web mining and also the application of data mining technique. Web mining technology is used to identify and analyze user's access patterns by using web server log data generated by web users when users access web site. So first of all, it is important that the data should be acquired in a reasonable way before applying data mining techniques to discover user access patterns from web log. The main task of data acquisition is to efficiently obtain users' detailed click behavior in the process of users' visiting Web site. This paper mainly focuses on data acquisition stage before the first stage of web usage mining data process with activities like data acquisition strategy and field extraction algorithm. Field extraction algorithm performs the process of separating fields from the single line of the log files, and they are also well used in practical application for a large amount of user data.

• The Journal of Korean Association of Computer Education
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• v.9 no.3
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• pp.85-96
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• 2006

This study analyzes a phenomenon observed in the problem-solving process using ICT that field learners prioritize functional and logical fields. The purpose of this study is to anticipate the future direction of education utilizing ICT and to explore what effort is needed to increase balanced ability of utilizing ICT in the area of education. To analyze the patterns of ICT usage in education, students were asked to solve the problems including functional and logical requests by using the program of framing document. That results were marked in accordance with standards framed in both functional and logical fields. As a result, students utilized the ICT functional field more than logical one. Therefore, we confirm learning through ICT is more effective on functional sides than on logical sides. We also confirm the excellency of ICT's functional sides in such variables as major, grade, computer capability and qualification, etc.

• Journal of the Korea Convergence Society
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• v.9 no.4
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• pp.271-283
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• 2018

This study aimed to investigate the effect of adolescent development environment including parenting attitude, peer relationship, and school environment on delinquent behavior, and between these relationships, the mediate effect of media environment such as computer and mobile devices. The $6^{th}$ year data from Korean Children & Youth Panel Survey (KCYPS) was used and the subjects were limited to 518 students of $7^{th}$ grade who are in their early adolescence. The result shows that adolescents under more affectionate, over involvement, and abusive parenting attitude will commit delinquent behaviors more frequently, and so does alienated youth from their friends. Parenting inconsistency and communication with friends make them use computer and cell phone more often, and excessive media usage increases adolescent's delinquent behavior. In conclusion, family environment and peer relation have influence on adolescents' delinquent behavior. Therefore, there is necessity to build development environment that prevent adolescents' delinquencies like parent education program or peer communication program for example. Also, proper education program for using computer or cell phone usage can reduce adolescents' delinquent behaviors, especially when its addictive aspect was recently issued.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.1
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• pp.69-78
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• 2015

Recently, due to the development of next-generation computing devices and high-performance network, VDI (Virtual Desktop Infrastructure) is receiving a great deal of attention from IT market as an essential part of cloud computing. VDI enables to host multiple, individual virtual machines that are provisioned from servers located at the data center by using hypervisor. One of the critical issues related to VDI is to reduce the performance difference between virtual machines and physical ones. In this paper, we present a real-time VM monitoring system, called SETMOV, that is able to collect the real-time resource usage information. We also present the performance results using iozone to verify SETMOV.

• Proceedings of the Korean Society for Bioinformatics Conference
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• 2004.11a
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• pp.138-149
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• 2004

In this study, we analyzed the gene expression data of Saccharomyces cerevisiae obtained from Holstege et al. 1998 to understand the relationship between expression level and nucleotide sequence of a gene. First, the correlation between gene expression and percent composition of each type of nucleotide was computed. It was observed that nucleotide 'G' and 'C' show positive correlation (r ${\geq}$ 0.15), 'A' shows negative correlation (r ${\approx}$ -0.21) and 'T' shows no correlation (r ${\approx}$ 0.00) with gene expression. It was also found that 'G+C' rich genes express more in comparison to 'A+T' rich genes. We observed the inverse correlation between composition of a nucleotide at genome level and level of gene expression. Then we computed the correlation between dinucleotides (e.g. AA, AT, GC) composition and gene expression and observed a wide variation in correlation (from r = -0.45 for AT to r = 0.35 for GT). The dinucleotides which contain 'T' have wide range of correlation with gene expression. For example, GT and CT have high positive correlation and AT have high negative correlation. We also computed the correlation between trinucleotides (or codon) composition and gene expression and again observed wide range of correlation (from r = -0.45 for ATA r = 0.45 for GGT). However, the major codons of a large number of amino acids show positive correlation with expression level, but there are a few amino acids whose major codons show negative correlation with expression level. These observations clearly indic ate the relationship between nucleotides composition and expression level. We also demonstrate that codon composition can be used to predict the expression of gene in a given condition. Software has been developed for calculating correlation between expression of gene and codon usage.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.6
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• pp.93-106
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• 2011

In this paper we describe an efficient and easy to use internet stopper, which is called AINS (Automatic Internet Stopper), which uses ARP spoofing scheme. Instead of forwarding packets to router for the case of hacking, in ARP spoofing, the AINS ignores all the packets so that internet stopping operates. The AINS program needs to be installed only in manager computer that does not require additional agent program. In addition to setting manually the stopping computer list, it is able to indentify network nodes automatically by analyzing broadcasting packets. The experimental results show that less than 4 secs for spoofing interval is enough for blocking internet usage regardless the number of computers and therefore network overhead is negligible. The AINS can indentify and control network nodes not only on same subnet but also on different subnet only if they are connected onto same ethernet switch physically. It is being used for an efficient tool for controling internet usage of university computer laboratory and also for an efficient network management.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.3
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• pp.127-135
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• 2015

Context-aware mobile cloud computing is a new promising paradigm that allows to improve user experience by analyzing contextual information such as user location, time of the day, neighboring devices and current activity. In this paper we provide performance study of context-aware mobile cloud computing system with Volare middleware. Volare monitors the resources and context of the device. and dynamically adapts cloud service requests accordingly, at discovery time or at runtime. This approach allows for more resource-efficient and reliable cloud service discovery, as well as significant cost savings at runtime. We also have studied the performance of context-aware mobile cloud computing for different quality of service (QoS) adaptation policies. Our simulations results show that when battery level is low and CPU usage is high and user cannot maintain the initial QoS, service cost is decreased according to current adaptation policy. In conclusion, the current adaptation policy suggested in this paper may improve user experience by providing a dynamically adapted service cost according to a situation.

• Journal of Preventive Medicine and Public Health
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• v.37 no.4
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• pp.312-320
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• 2004

Objectives : An outbreak of acute hemorrhagic conjunctivitis (AHC) caused by coxsackie A24 (CA24) virus occurred in South Korea in 2002. CA24 was isolated for the first time from patients with AHC. Therefore, this study was conducted to understand the transmission routes and prevent another AHC outbreaks. Methods : The authors conducted a questionnaire survey among 1,730 students from 2 middle schools and 1 technical high school in Gyeongju city. For statistical analysis the chi-square test was used, and chi-square for trend method showing a level of significance less than p<0.05 was proven to be significant. Variables which were proven to be significant in univariate analysis were analysed by multiple logistic regression. Results : The attack rate was 57.1%. The student groups with rubbing one s own eyes, computer usage, and sharing cellular phone had a significantly higher AHC attack rate (p<0.05). According to the multiple logistic regression, the odds ratios for male, high school, computer use, sharing cellular phone, and rubbing one s own eyes were significant (p<0.05). Conclusion : The most significant feature of this outbreak was that many students rubbed their own eyes following contact with AHC patients in a deliberate attempt to avoid going to school. Other transmission methods were computer usage and sharing cellular phone. In the future, health and school authorities must plan new strategies for the prevention of AHC.