• Journal of Digital Convergence
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• v.12 no.4
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• pp.21-32
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• 2014

Recently, the number of Koreans who use smartphones has increased drastically; many use smartphones to learn English. In this study, one hundred Korean adult ELT (English language teaching) learners were surveyed to investigate their use of smartphones and factors influencing such use. For comparison, sixty-two students of a Korean cyber university were surveyed; these students were able to study using their smartphones in a smart campus environment. The research results showed that both groups positively used smartphones frequently, and that many intended to continue using them. With regard to ELT, both groups intended to learn English using their smartphones. Furthermore, they preferred certain types of ELT content: thirty-minute or less learning sessions, receptive English skills that focused on listening and reading, and short units of framed language items such as pronunciation and vocabulary. However, few of the respondents in both groups installed ELT apps on their smartphones, and few of the ELT apps satisfied them. The cyber university students responded similarly about smartphone use, although their responses regarding smartphone use for ELT purposes were less positive. These results indicate that the goal of cyber universities in achieving optimum learning outcomes through smart learning and the smart campus has not yet been realized.

• Science of Emotion and Sensibility
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• v.24 no.2
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• pp.13-24
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• 2021

In level 5 (mind-off) of autonomous driving, the autonomous vehicle passengers are expected to have various activities such as face-to-face meetings, working, relaxing, and watching movies. In particular, various changes in the interior space of the vehicle are expected. Moreover, according to the survey conducted by the American Automobile Association, 73% of the respondents reported that they were afraid to board autonomous vehicles. In level 5 of autonomous driving, the subject of safety was expected to be transferred to autonomous vehicles; thus, research should be conducted from the user's perspective. Recently, various studies have been conducted to secure the safety of fully autonomous vehicles. However, there are limited studies addressing the psychological safety of actual passengers. Therefore, this study conducted a questionnaire based on the AHP technique. Consequently, the automobile safety system's priority for securing passengers' psychological safety according to each type of indoor behavior was derived, and the interior space for securing the psychological stability of passengers was suggested based on the obtained results. This study offers a new direction for interior space design, satisfying the psychological safety of passengers. This study is important because it advocates that the interior environment of fully autonomous driving cars is expected to be designed to secure the user's psychological safety.

• Journal of the Korea Convergence Society
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• v.3 no.3
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• pp.7-12
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• 2012

mVoIP (mobile Voice over Internet Protocol) service is a technology to transmit voice data through an IP network using mobile device. mVoIP provides various supplementary services with low communication cost. It can maximize the availability and efficiency by using IP-based network resources. In addition, the users can use voice call service at any time and in any place, as long as they can access the Internet on mobile device easily. However, SIP on mobile device is exposed to IP-based attacks and threats. Observed cyber threats to SIP services include wiretapping, denial of service, and service misuse, VoIP spam which are also applicable to existing IP-based networks. These attacks are also applicable to SIP and continuously cause problems. In this study, we analysis the threat and vulnerability on mVoIP service and propose several possible attack scenarios on existing mobile VoIP devices. Based on a proposed analysis and vulnerability test mechanism, we can construct more enhanced SIP security mechanism and stable mobile VoIP service framework after eliminating its vulnerability on mobile telephony system.

• The KIPS Transactions:PartC
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• v.17C no.1
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• pp.89-98
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• 2010

In current digital broadcasting systems, GEM(Globally Executable MHP)-based middlewares such as MHP(Multimedia Home Platform), OCAP(OpenCable Application Platform), ACAP(Advanced Common Application Platform) are the norm. Despite much of the common characteristics shared, such as MPEG-2 and DSM-CC(Digital Storage Media-Command and Control) protocols, the information and data structures they need are slightly different, which results in incompatibility issues. In this paper, in line with an effort to develop an integrated DTV middleware, we propose a general-purpose, reconfigurable DSM-CC architecture for supporting various standard GEM-based middlewares without code modifications. First, we identify DSM-CC components that are common and thus can be shared by all GEM-based middlewares. Next, the system is provided with middleware-specific information and data structures in the form of XML. Since the XML information can be parsed dynamically at run time, it can be interchanged either statically or dynamically for a specific target middleware. As for the performance issues, the response time and usage frequency of DSM-CC module highly contribute to the performance of STB(Set-Top-Box). In this paper, we also propose an efficient application cache management strategy and evaluate its performance. The performance result has shown that the cache strategy reflecting user preferences greatly helps to reduce response time for executing application.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.11
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• pp.369-382
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• 2015

Energy aware server clusters aim to reduce power consumption at maximum while keeping QoS(quality of service) compared to energy non-aware server clusters. They adjust the power mode of each server in a fixed or variable time interval to activate only the minimum number of servers needed to handle current user requests. Previous studies on energy aware server cluster put efforts to reduce power consumption or heat dissipation, but they do not consider energy efficiency well. In this paper, we propose an energy efficient cluster management method to improve not only performance per watt but also QoS of the existing server power mode control method based on autonomous learning. Our proposed method is to adjust server power mode based on a hybrid approach of autonomous learning method with multi level thresholds and power consumption prediction method. Autonomous learning method with multi level thresholds is applied under normal load situation whereas power consumption prediction method is applied under abnormal load situation. The decision on whether current load is normal or abnormal depends on the ratio of the number of current user requests over the average number of user requests during recent past few minutes. Also, a dynamic shutdown method is additionally applied to shorten the time delay to make servers off. We performed experiments with a cluster of 16 servers using three different kinds of load patterns. The multi-threshold based learning method with prediction and dynamic shutdown shows the best result in terms of normalized QoS and performance per watt (valid responses). For banking load pattern, real load pattern, and virtual load pattern, the numbers of good response per watt in the proposed method increase by 1.66%, 2.9% and 3.84%, respectively, whereas QoS in the proposed method increase by 0.45%, 1.33% and 8.82%, respectively, compared to those in the existing autonomous learning method with single level threshold.

• Journal of Digital Contents Society
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• v.14 no.4
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• pp.419-428
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• 2013

Real-time accessibility and agility are required in u-commerce under ubiquitous computing environment. Most of the existing recommendation techniques adopt the method of evaluation based on personal profile, which has been identified with difficulties in accurately analyzing the customers' level of interest and tendencies, as well as the problems of cost, consequently leaving customers unsatisfied. Researches have been conducted to improve the accuracy of information such as the level of interest and tendencies of the customers. However, the problem lies not in the preconstructed database, but in generating new and diverse profiles that are used for the evaluation of the existing data. Also it is difficult to use the unique recommendation method with hierarchy of each customer who has various characteristics in the existing recommendation techniques. Accordingly, this dissertation used the implicit method without onerous question and answer to the users based on the data from purchasing, unlike the other evaluation techniques. We applied FRAT technique which can analyze the tendency of the various personalization and the exact customer.

• KIISE Transactions on Computing Practices
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• v.20 no.12
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• pp.632-639
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• 2014

In this paper, we propose a PC's self-monitoring system for protecting illegal outflow of important personal files, which are managed in the Windows environment PC. This paper is based on the idea that it should be a read (access) file operation in order to outflow files through the network. To compare the information (name, some content) obtained from all operations of the reading of the 'Windows File System Driver' and captured transmission packets of mini port of 'Windows NDIS (Network Driver Interface Specification) Driver', and, if two pieces of information match, this system will determine the transmission to user. In this paper, tentatively, we developed a function to gather file information about file read operation and developed a function for transmission packet capture. This demonstration implementation showed that the proposed process has validity and the proposed process verified that it does not significantly affect the PC's performance.

• The Journal of the Korea Contents Association
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• v.9 no.11
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• pp.212-224
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• 2009

Proliferation of high performance internet infrastructures finally allows their users download a single copy of regular movie just within in a couple of seconds. Ease of accesses to the software for downloading consequently leads them insensitive to the ethics or legitimacy of their conduct. Thus, strong legal action is enforced for piracy over nationally through strengthen the copyright law. We in this paper conducted a survey to see whether netizens prefer to download just for the matter of their convenience. Whilst the level of awareness is addressed even in a far-fetched manner in the area of music piracy and computer software piracy, the case of movie is much different in that we even fail to find any survey that has been made for movie piracy. The survey has been made by devising questionnaires for netizens and it was posted web WorldSurvey, which is the most prominent online survey site in Korea. To our surprise, 9 out of 10 respondents expressed they actually resort to illegal downloading for the reason of convenience. We realized one more surprise. More than 95% of netizens conspicuously aware of their downloading behaviors are mischievous and illegal without reservation.

• Journal of the Korea Convergence Society
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• v.2 no.1
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• pp.1-6
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• 2011

The wide use of mobile devices such as smart phones makes the mobile commerce industry be growing-up rapidly. In mobile commerce security, how to secure a copyright of mobile contents and how to distribute it are of major concerns. The user can carry the smart phone regardless of the places. Thus the utilization of it is very high than that of personal computers. The USIM(Universal Subscriber Information Module) inserted in the smart phone binds the user with the device. This means that the smart phone can be used to represent the owner's identity. In this paper, we develop the mobile ID based digital signature scheme. We create the mobile ID by combining USIM with the user's random secret value. In addition, undeniable property of our signature scheme can make ID based applications such as mobile voting and mobile content distribution be possible with the smart phone.

• The Journal of the Korea Contents Association
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• v.12 no.1
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• pp.9-16
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• 2012

Though Android-based smart phones are being released in Korea, Korean TTS engine is not built on them and Google has not announced service or software developer's kit related to Korean TTS officially. Thus, application developers who want to include Korean TTS capability in their application have difficulties. In this paper, we design and implement Android OS-based Korean TTS system and service. For speed, text preprocessing and synthesis libraries are implemented using Android NDK. By using Java's thread mechanism and the AudioTrack class, the response time of TTS is minimized. For the test of implemented service, an application that reads incoming SMS is developed. The test shows that synthesized speech are generated in real-time for random sentences. By using the implemented Korean TTS service, Android application developers can transmit information easily through voice. Korean TTS service proposed and implemented in this paper overcomes shortcomings of the existing restrictive synthesis methods and provides the benefit for application developers and users.