• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.674-677
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• 2012

An operating system acts as an intermediary between your computer hardware and computer users to perform, that the user can run the program provides an environment in which. Therefore, the main purpose of the operating system having a computer available for your convenience and to effectively manage computer hardware. The popularization of the people who use computers, improve hardware performance, advent of the internet, popularity of wireless networks, Smartphone and Tablet PC appearance, advent of virtualization technologies and cloud computing, etc. began making changes to the operating system. In particular, cloud computing environments based on server virtualization and using a variety of wired and wireless devices with internet connection, a Web-based operating system was born. In this paper, the definition of a Web-based operating system, types and characteristics, an analysis of the pros and cons, and find out about the future prospects.

• Journal of IKEEE
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• v.13 no.4
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• pp.29-36
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• 2009

The packet loss and the disconnection during handoff are the most critical problems which degrade the video quality in wireless video streaming. To cope with these problems, we propose an efficient video streaming method in this paper, which does not only dynamically adjust the video transmission rate based on the raptor forward error correction (FEC) level, but also minimize the error propagation during handoff. Firstly, the channel bandwidth of the wireless broadband internet, called WiBro, is estimated by analyzing channel parameters including the carrier to interference and noise ratio (CINR) and the handoff. Secondly, the streaming server adjusts the next transmission rate according to the estimated channel bandwidth and the raptor FEC level to avoid packet error. Also, the encoder performs the intra refresh method that inserts an intra frame (I-frame) right after handoff to reduce the error propagation effectively. Experimental results indicate that the proposed method can improve the performance of the video streaming over WiBro network.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.4
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• pp.57-61
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• 2014

Zeroboard is a public bulletin board that can support PHP and MySQL. It has been used by many people because it is easy to use, but there is no more updates after Zeroboard4. So, there is a problem that its administrator will have nothing to do about it if zeroboard has a vulnerability. In this paper, we will discuss about CSRF(Cross Site request Forgery) which is developed and expanded by XSS(Cross Site Scripting). Also, we will find CSRF attacks and suggest an alternative method using VM-ware. The main features and contributions of the proposed method are as follows. First, make an environment construction using VM-ware and other tools. Second, analyze and prepare vulnerabilities using Proxy server. Performance evaluation will be conducted by applying possible countermeasure.

• Journal of KIISE
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• v.44 no.9
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• pp.966-975
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• 2017

In Internet of Things (IoT), the aim of the nodes (called 'Things') is to exchange information with each other, whereby they gather and share information with each other through self decision-making. Therefore, we cannot apply existing aggregation algorithms of Wireless sensor networks that aim to transmit information to only a sink node or a central server, directly to the IoT environment. In addition, since existing algorithms aggregate information from all sensor nodes, problems can arise including an increasing number of transmissions and increasing transmission delay and energy consumption. In this paper, we propose the clustering and property based data exchange method for energy efficient information sharing. First, the proposed method assigns the properties of each node, including the sensing data and unique resource. The property determines whether the node can respond to the query requested from the other node. Second, a cluster network is constructed considering the location and energy consumption. Finally, the nodes communicate with each other efficiently using the properties. For the performance evaluation, TOSSIM was used to measure the network lifetime and average energy consumption.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.4
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• pp.35-43
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• 2017

In this paper, we propose indoor IoT monitoring system based on visible light communication using smart phone with attracting attentions in recent wireless communication. The main features and contributions of the proposed system developed in this paper are as follows. First, the actual data generated within indoor can be processed via the server by using only the visible light communication. Second, the collected data by using the visible light communication can be monitered by smart phone. Performance evaluation of the proposed system is performed under illumination of the normal fluorescent lamps. We first check successful transmission between transmitting module and receiving module of the data collection system. The monitoring system is tested according to the change of the degree of condensing and distance of the LED and the decoding success rate of the proposed smart phone application. We expect that the proposed system can be applied for indoor and outdoor IoT areas together.

• Journal of Internet Computing and Services
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• v.17 no.5
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• pp.89-95
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• 2016

In a software testing domain, test case prioritization techniques improve the performance of regression testing, and arrange test cases in such a way that maximum available faults be detected in a shorter time. User-sessions and cookies are unique features of web applications that are useful in regression testing because they have precious information about the application state before and after making changes to software code. This approach is in fact a user-session based technique. The user session will collect from the database on the server side, and test cases are released by the small change configuration of a user session data. The main challenges are the effectiveness of Average Percentage Fault Detection rate (APFD) and time constraint in the existing techniques, so in this paper developed an intelligent framework which has three new techniques use to manage and put test cases in group by applying useful criteria for test case prioritization in web application regression testing. In dynamic weighting approach the hybrid criteria which set the initial weight to each criterion determines optimal weight of combination criteria by evolutionary algorithms. The weight of each criterion is based on the effectiveness of finding faults in the application. In this research the priority is given to test cases that are performed based on most common http requests in pages, the length of http request chains, and the dependency of http requests. To verify the new technique some fault has been seeded in subject application, then applying the prioritization criteria on test cases for comparing the effectiveness of APFD rate with existing techniques.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.6
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• pp.83-94
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• 2016

Recent cloud, big data, there is a problem for the architectural security vulnerability to the server platforms of various fields such as artificial intelligence occurs consistently, but using the virtualization technology. In addition, most secure virtualization technology is known to be dependent on the type is limited and the platform provider. This paper presents a method for mutual authentication for secure data between multiple instances of a shared virtualized environment. The proposed method was designing a security architecture in consideration of the mutual authentication between multiple independent instances, and enhance the safety of a security protocol for sharing data by applying a key chain techniques. Performance analysis results and the existing security architecture demonstrated that protect each virtualized instances of the session and the other way, a compliance effectiveness for each instance of the mutual authentication process.

• KIISE Transactions on Computing Practices
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• v.23 no.12
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• pp.691-697
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• 2017

Volcanic ash has been predicted to be the main source of damage caused by a potential volcanic disaster around Mount Baekdu and the regions of the Korean peninsula. Computer simulations to predict the diffusion of volcanic ash should be performed according to prevalent meteorological situations within a predetermined time. Therefore, a workflow using pipelining is proposed to parallelize the software used for this computation. Due to the nature of volcanic calamities, the simulations need to be carried out for various plausible conditions given that the parameters cannot be precisely determined during the simulations, even at the time of a volcanic eruption. Among the given conditions, computations need to be first performed for the condition with the highest probability so that a response to the volcanic disaster can be provided using these results. Further action can then be performed later based on subsequent results. The computations need to be performed using a volcanic disaster damage prediction system on a computing server with limited computing performance. Hence, an optimal distribution of the computing resources is required. We propose a method through which specific data can be provided first to the proposed pipeline-based workflow.

• KIISE Transactions on Computing Practices
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• v.23 no.12
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• pp.670-676
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• 2017

Naval combat systems use real-time processing and compositing of collected information to provide the optimal combat capabilities that maximize survival and ensure mission effectiveness. The software for a combat system has dozens to thousands of components depending on the size of the system, and the communication between the components is achieved via DDS. Although the message interface of the combat system is managed through MDMS, an increase in the system size can result in problems such as the deterioration of the development efficiency. In this paper, we implement XMDMS to operate a distributed processing environment and then solve the problem of the reduction in the development efficiency caused by a load at the server. The experimental results shows that XMDMS improves the processing delay and network performance compared to MDMS.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.8
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• pp.472-483
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• 2002

This paper presents the design and implementation of a cache file system, umcFS, which is specifically designed to provide an efficient caching and transmission of streaming media. The proposed file system is based on the concept of file disk and implemented as an application level on top of a general-purpose file system. The file disk favors the continuity of cached media and provides an efficient I/O mechanism for cache server. umcFS statically allocates control blocks as well as media cache blocks. These blocks are referenced by the single-level indirect management structure. As the file system is designed as an application level, it is easy to develop and port to other systems. The performance of the implemented system shows that umcFS performs about 13% better than the native file system in randomly accessing the cache blocks of 1024KB.