• Journal of KIISE
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• v.43 no.7
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• pp.744-750
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• 2016

Recent cloud infrastructures provide competitive performances and operation costs for many internet services through pay-per-use model. Particularly, object storages are highlighted, as they have unlimited file holding capacity and allow users to access the stored files anytime and anywhere. Several lines of research are based on cloud-backed file systems, which support traditional POSIX interface rather than RESTful APIs via HTTP. However, these existing file systems handle all files with uniform size backing objects. Consequently, the accesses to cloud object storages are likely to be inefficient. In our research, files are profiled according to characteristics, and appropriate backing unit sizes are determined. We experimentally verify that different backing unit sizes for the object storage improve the performance of cloud-backed file systems. In our comparative experiments with S3QL, our prototype cloud-backed file system shows faster performance by 18.6% on average.

• Journal of KIISE:Information Networking
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• v.37 no.5
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• pp.386-395
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• 2010

Widespread deployment of infrastructure WLANs has made Wi-Fi an integral part of today's Internet access technology. Despite its crucial role in affecting end-to-end performance, past research has focused on MAC protocol enhancement, analysis, and simulation-based performance evaluation without sufficiently considering a misbehavior stemming from capture effect. It is well known that the capture effect occurs frequently in wireless environment and incurs throughput unfairness between nodes. In this paper, we propose a novel Fair MAC algorithm which achieves fairness even under physically unfair environment. While satisfying the fairness, the proposed algorithm maximizes the system throughput. Extensive simulation results show that the proposed Fair MAC algorithm substantially improves fairness without throughput reduction.

• The KIPS Transactions:PartC
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• v.13C no.4 s.107
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• pp.405-414
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• 2006

We present a symptom based taxonomy for network security. This taxonomy classifies attacks in the network using early symptoms of the attacks. Since we use the symptom it is relatively easy to access the information to classify the attack. Furthermore we are able to classify the unknown attack because the symptoms of unknown attacks are correlated with the one of known attacks. The taxonomy classifies the attack in two stages. In the first stage, the taxonomy identifies the attack in a single connection and then, combines the single connections into the aggregated connections to check if the attacks among single connections may create the distribute attack over the aggregated connections. Hence, it is possible to attain the high accuracy in identifying such complex attacks as DDoS, Worm and Bot We demonstrate the classification of the three major attacks in Internet using the proposed taxonomy.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.1
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• pp.97-105
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• 2015

Recently, due to an explosive growth of the internet traffic, the limitations of a current framework for a mobility management have been focused. The current centralized mobility management is prone to several problems and limitations: suboptimal routing, low scalability, signaling overhead, and a single point of failure. To overcome these problems and limitations, IETF is working about the distributed mobility management scheme that the centralized mobility functions of HA(Home Agents) are distributed to networks edges such as access routers. These distributions of mobility functions overcome the limitations of the centralized mobility managements and go with the trend of flat networks e.g. more simple network architecture. This paper analyzes the distributed mobility management based on Proxy Mobile IPv6 and demonstrates the performance superiority.

• Korean Security Journal
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• no.16
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• pp.283-304
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• 2008

The development of IT technology help citizens demand information and public services through internet that they want, and the changes also help the government converge public opinions and become important measures for citizens to participate in deciding governmental policies. So, this thesis makes an overture of a possibility for utilizing PCRM, a way for citizens to participate in Police Administration, by utilizing IT technologies in which everybody can participate without difficulty. The utilization ways are, on a large scale, classified with a macroscopic aspect and microscopic aspect. One of the macroscopic aspects is, first, the consideration of access to services and convenience in utilization. Second, services should have a both-sidedproperty. Ultimately, citizens'participation should have a positive mutual participation level. One of the microscopic aspects is, first, that the police organizations have to establish a strategy to analyze and fractionate customers. Second, the police organizations have to make an effort to develop policy services and P.R strategies. Third, police organizations have to make an effort to manage customers. Fourth, police organizations have to execute customer management in general. So, all of the police organizations have to maintain unity, to some extent, about citizen participation plazas. In addition, at the same time, consciousness aspects have to be accompanied for the reasonable utilization of PCRM. Citizens have to cultivate citizen consciousness, ownership consciousness for society, and positive participation consciousness to solve social problems.

• Journal of the Korean Society for Library and Information Science
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• v.43 no.3
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• pp.335-354
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• 2009

In the knowledge and information society, there is an increasing importance of information, being unable to access this information becomes a huge disadvantage. Blind and visually impaired users who are using assistant equipment such as screen readers are the very class that is having trouble accessing the web content that public libraries provide. In this research 10% of each region's libraries were picked as a research sample. Most of the web content that the public libraries provided did not meet the Internet web content accessibility guidelines as a Korean standard. Also evaluation into web accessibility by the visually impaired was also low. This research suggests some solutions for libraries to reduce the disadvantages that are put upon visually impaired people from various views such as perceivable, operable, understandable, and robust.

• Nutrition Research and Practice
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• v.2 no.2
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• pp.114-120
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• 2008

A diet habit, which is developed in childhood, lasts for a life time. In this sense, nutrition education and early exposure to healthy menus in childhood is important. Children these days have easy access to the internet. Thus, a web-based nutrition education program for children is an effective tool for nutrition education of children. This site provides the material of the nutrition education for children with characters which are personified nutrients. The 151 menus are stored in the site together with video script of the cooking process. The menus are classified by the criteria based on age, menu type and the ethnic origin of the menu. The site provides a search function. There are three kinds of search conditions which are key words, menu type and "between" expression of nutrients such as calorie and other nutrients. The site is developed with the operating system Windows 2003 Server, the web server ZEUS 5, development language JSP, and database management system Oracle 10 g.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.240-243
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• 2010

Smart Phone supplies are diffused and substitute the Internet PC with Mobile communications which they are applied. Smart Phone in Smart Grid where electric power watch and the IT of existing amalgamate are used with business. Consequently from Smart Grid network connections which lead Smart Phone in about connection and control in about security vulnerabilities and Smart Grid networks the research is necessary in about vulnerability. It uses Smart Phone from the present paper and when approaching electric power watch systems which lead Smart Grid networks, it researches in about connection vulnerability. Also it uses Smart Phone and after connecting in Smart Grid networks a vulnerability in seizure possibility and, electric power information and control information, about private data etc. access authority it analyzes with the problem point which occurs it confronts it researches. And the research direction for a security reinforcement under presenting boil in about Smart Grid network security vulnerabilities which lead Smart Phone.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.669-671
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• 2010

IStorage is a technology, which can use resources of server PC by using Android Phone supporting wireless internet access. IStorage utilizes resources of server PC through WebDAV protocol. And with GUI interface, Users upload their resources to the server PC and They can perform various kinds of works like Opening, Searching, Deleting and Downloading files. Since it is possible for them to use resources of server PC as if they are originally stored in their mobile devices, there is no limit on using the functions such as watching movies, listening musics and opening document files in real time. We expect this study can to overcome the limitation of storage space and also be a useful technology in the smart phone market.

• Journal of the Korea Society of Computer and Information
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• v.19 no.11
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• pp.73-79
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• 2014

In the period of rising the importance of software education, unplugged activities has drawn attention as one of the various educational approaches. It has a good reputation in educational effectiveness and usefulness in an aspect of learning the principle of computer science. This paper proposes the tool that allows unplugged learning contents to be used in the web based on HTML5 in order to enhance its merits and accessibilities. The proposed tool is easy to access because it is operated on the level of web browser with no plug in or extra application programs. In addition, as a learner focused contents aiming at interaction on the web environment, it is well organized for school class room.