• KIPS Transactions on Computer and Communication Systems
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• v.5 no.12
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• pp.447-454
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• 2016

The research on multipath routing has been studied to solve the problem of frequent path breakages due to node and link failures and to enhance data delivery reliability in wireless sensor networks. In the multipath routing, mobile sinks such as soldiers in battle fields and rescuers in disaster areas bring about new challenge for handling their mobility. The sink mobility requests new multipath construction from sources to mobile sinks according to their movement path. Since mobile sinks have continuous mobility, the existing multipath can be exploited to efficiently reconstruct to new positions of mobile sinks. However, the previous protocols do not address this issue. Thus, we proposed an efficient multipath reconstruction protocol called LGMR for mobile sinks in wireless sensor networks. The LGMR address three multipath reconstruction methods based on movement types of mobile sinks: a single hop movement-based local multipath reconstruction, a multiple hop movement-based local multipath reconstruction, and a multiple hop movement-based global multipath reconstruction. Simulation results showed that the LGMR has better performance than the previous protocol in terms of energy consumption and data delivery delay.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.8
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• pp.317-326
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• 2013

In this paper, we present an effective method for comparing control flow graphs which represent static structures of binary programs. To compare control flow graphs, we measure similarities by comparing instructions and syntactic information contained in basic blocks. In addition, we also consider similarities of edges, which represent control flows between basic blocks, by edge extension. Based on the comparison results of basic blocks and edges, we match most similar basic blocks in two control flow graphs, and then calculate the similarity between control flow graphs. We evaluate the proposed edge extension method in real world Java programs with respect to structural similarities of their control flow graphs. To compare the performance of the proposed method, we also performed experiments with a previous structural comparison for control flow graphs. From the experimental results, the proposed method is evaluated to have enough distinction ability between control flow graphs which have different structural characteristics. Although the method takes more time than previous method, it is evaluated to be more resilient than previous method in comparing control flow graphs which have similar structural characteristics. Control flow graph can be effectively used in program analysis and understanding, and the proposed method is expected to be applied to various areas, such as code optimization, detection of similar code, and detection of code plagiarism.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.1
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• pp.115-119
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• 2010

As the subjects of education has been changed from the instructors to learners, a web-based self-directed learning which can accelerate the initiative of learners and can be free from the restriction of time and space has been received attention. In this paper, the web-based self-directed learning system was designed. For the design, to make the learners build their own lecture plan, the service was designed to provide three kinds of lectures of video clip, slide lecture, and e-text lecture that were focused on various lecture contents. In addition, a learner and an assistant was man to man matched to enable the on-line mentoring for mutual communication between learners and assistants. Implementation was carried out by three sets of module - Manager, Learner and Assistant - that were applied to the real educational activities. The survey on satisfaction for the education, efficiency of ability improvement, and educational intelligibility for the attendants on the education showed more than 67.2% of satisfaction in satisfaction for the education. Furthermore, more than 86.9% of attendants replied that their ability were improved after the education of this system. The educational system realized in this paper shows effectiveness for the self-directed learning.

• Journal of KIISE:Computing Practices and Letters
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• v.11 no.5
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• pp.401-415
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• 2005

Owing to the improved wireless communication technologies, it is possible to provide streaming service of multimedia with PDAs and mobile phones in addition to desktop PCs. Since mobile client devices have low computing power and low network bandwidth due to wireless network, the transcoding technology to adapt media for mobile client devices considering their characteristics is necessary. Transcoding servers transcode the source media to the target media within corresponding grades and provide QoS in real-time. In particular, an effective load balancing policy for transcoding servers is inevitable to support QoS for large scale mobile users. In this paper, the resource weighted load distribution policy is proposed for a fair load balance and a more scalable performance in cluster-based transcoding servers. Our proposed policy is based on the resource weighted table and number of maximum supported users, which are pre-computed for each pre-defined grade. We implement the proposed policy on cluster-based transcoding servers and evaluate its fair load distribution and scalable performance with the number of transcoding servers.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.10
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• pp.1808-1814
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• 2008

In addition to RBL function, which is used to applying for spam e-mail filtering, as an effective way to deal with the recently widespread spam types, this paper proposes how to extract URL that was comprised in the original e-mail, apply it to RBL, and expand it. The BotNet, which is used to using for sending spam mails these days, has a problem that it is not able to solve with the distributed addresses of sent mails in spam e-mails. In general, as these spam e-mails are sent from the infected Zombi PC of individual user, the sent address itself is not efficient and is meaningless to use in RBL. As an effective way to filter spam e-mail sent by BotNet, this paper analyzes URLs that contained in the original spam e-mail and proposes how to effectively improve filter rate, based on the distribution data of URL site tempting users. This paper proposes the sending mechanism of spam e-mails from BotNet and the methods to realize those types of spam e-mails. In order to gather analyzable spam e-mails, this paper also carries out an experiment by configuring trap system of spam e-mail. By analyzing spam e-mails, which have been received during the certain period of experiment, this paper shows that the expanded RBL method, using URLs that contained in spam e-mails, is effective way to improve the filter distribution of spam e-mail.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.9
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• pp.1575-1583
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• 2008

Wireless sensor network has merit of low-power, low-cost and self-organization network, so there are many researches substituted for existing wire network. As structure reinforcement work need a high accuracy, many sensors are installed in structure and connected with data logger for monitoring. However this wire data logger method takes a long time to install wires and installed wires obstruct to work. Additionally, wire data logger method represent sensor data by only numeric and graph, it is not able to support a rapid decision-making for working. To resolve wiring problem and support decision-making, we designed and implemented the monitoring system based in wireless sensor network. For verifying performance, accuracy and availability, we simulated and tested our system in real field. Consequently, wireless sensor network method is easier to install and deploy than wire data logger method, user is able to monitor instinctively and overall by 3D representation of structure and sensors, and it show not only accuracy but also performance for many sensors.

• Korean Journal of Remote Sensing
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• v.26 no.2
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• pp.263-275
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• 2010

KOSC(Korea Ocean Satellite Center), the primary operational organization for GOCI(Geostationary Ocean Color Imager), was established in KORDI(Korea Ocean Research & Development Institute). For a stable distribution service of GOCI data, various systems were installed at KOSC as follows: GOCI Data Acquisition System, Image Pre-processing System, GOCI Data Processing System, GOCI Data Distribution System, Data Management System, Total Management & Control System and External Data Exchange System. KOSC distributes the GOCI data 8 times to user at 1-hour intervals during the daytime in near-real time according to the distribution policy. Finally, we introduce the KOSC website for users to search, request and download GOCI data.

• Convergence Security Journal
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• v.18 no.5_1
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• pp.113-120
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• 2018

Today, the development of information and communication technology is rapidly increasing the number of users of network-based service, and enables real-time information sharing among users on the Internet. There are various methods in the information sharing process, and information sharing based on portal service is generally used. However, the process of information sharing serves as a cause of illegal activities in order to amplify the social interest of the relevant stakeholders. Public opinion attack using macro function can distort normal public opinion, so security measures are urgent. Therefore, security measures are urgently needed. Macro attacks are generally defined as attacks in which illegal users acquire multiple IP or ID to manipulate public opinion on the content of a particular web page. In this paper, we analyze network path information based on traceback for macro attack of a specific user, and then detect multiple access of the user. This is a macro attack when the access path information for a specific web page and the user information are matched more than once. In addition, when multiple ID is accessed for a specific web page in the same region, it is not possible to distort the overall public opinion on a specific web page by analyzing the threshold count value.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.3
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• pp.149-156
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• 2019

In the field of maintenance of power transmission lines, drones have been used for their patrol and inspection by KEPCO since 2017. This drone technology was originally developed by KEPCO Research Institute, and now workers from four regional offices of KEPCO have directly applied this technology to the drone patrol and inspection tasks. In the drone inspection system, a drone with an optical zooming camera and a thermal camera can fly automatically along the transmission lines by the ground control system developed by KEPCO Research Institute, but its camera gimbal has been remotely controlled by a field worker. Especially the drone patrol and inspection has been mainly applied for the transmission lines in the inaccessible areas such as regions with river-crossings, sea-crossings and mountains. There are often communication disruptions between the drone and its remote controller in such extreme fields of mountain areas with many barriers. This problem may cause the camera gimbal be out of control, even though the inspection drone flies along the flight path well. In addition, interference with the reception of real-time transmitted videos makes the field worker unable to operate it. To solve these problems, we have developed the auto-tracking camera gimbal system with deep learning method. The camera gimbal can track the transmission line automatically, even when the transmitted video on a remote controller is intermittently unavailable. To show the effectiveness of our camera gimbal system, its field test results will be presented in this paper.

• Journal of the Korean Society for Computer Game
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• v.31 no.4
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• pp.81-89
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• 2018

The purpose of this study is to classify the types of internet personal game broadcasting in China and to examine viewers' preferences type of it. By targeting top 100 creators of Player-Unknown's Battleground streaming as a personal game broadcaster with over 100,000 followers, the game types were classified based on the purpose and characteristic of game broadcasting such as game play, entertainment, and audience participation. As a result, the type of internet personal game broadcasting in China was classified into progamer type, cooperative playing type, storytelling type, and reciprocal entertainment type. The progamer type was 38% and it was the highest proportion of Player-Unknown's Battlegrounds streaming. Next came storytelling type, cooperative playing type and reciprocal entertainment type with 25%, 19% and 18% respectively. In sum, progamer type and storytelling type which shows relatively low real - time communication with audiences accounted for a high percentage of 63%. This implies that the characteristics of the broadcast media focused on 'showing' have influenced the production and planning of personal game broad casting. The interactive characteristics of the platform of personal game broad casting can be expected to gradually change the conventional customs of broadcasting media.