• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.649-650
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• 2008

In order to resolve mechanical limit in HDD, recently, the hybrid hard disk combining HDD and a flash memory was launched. In this paper, we propose a simulator for hybrid hard disk which considers redirection, flushing and spin-down function to complement the difference between HDD and hybrid hard disk. The simulator was implemented in linux kernel 2.6.20 by modifying system calls related with file system. The experiment shows that the power consumption of hybrid hard disk is 47% smaller than that of hard disk in laptop PC.

• Journal of KIISE:Computer Systems and Theory
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• v.34 no.12
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• pp.683-695
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• 2007

NAND flash memory-based file systems cannot store their system-related information in the file system due to wear-leveling of NAND flash memory. This forces NAND flash memory-based file systems to scan the whole flash memory during their mounts. The mount time usually increases linearly according to the size of and the usage pattern of the flash memory. NAND flash memory has been widely used as the storage medium of mobile devices. Due to the fact that mobile devices have unstable power supply, the file system for NAND flash memory requires stable recovery mechanism from power failure. In this paper, we present design and implementation of a new NAND flash memory-based file system that provides fast mount and enhanced stability. Our file system mounts 19 times faster than JFFS2's and 2 times faster than YAFFS's. The stability of our file system is also shown to be equivalent to that of JFFS2.

• KIPS Transactions on Computer and Communication Systems
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• v.6 no.10
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• pp.415-420
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• 2017

Virtualization technique of OS-level is a new paradigm for deploying applications, and is attracting attention as a technology to replace traditional virtualization technique, VM (Virtual Machine). Especially, docker containers are capable of distributing application images faster and more efficient than before by applying layered image structures and union mount point to existing linux container. These characteristics of containers can only be used in layered file systems that support snapshot functionality, so it is required to select appropriate layered file systems according to the characteristics of the containerized application. We examine the characteristics of representative layered file systems and conduct write performance evaluations of each layered file systems according to the operating principles of the layered file system, Allocate-on-Demand and Copy-up. We also suggest the method of determining a appropriate layered file system principle for unknown containerized application by learning block I/O usage history of each layered file system principles in artificial neural network. Finally we validate effectiveness of artificial neural network created from block I/O history of each layered file system principles.

• The KIPS Transactions:PartC
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• v.12C no.6 s.102
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• pp.865-874
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• 2005

The information stored in the computer system needs to be protected from unauthorized access, malicious destruction or alteration and accidental inconsistency. In this paper, we propose an intrusion detection system based on sensor concept for defecting and preventing malicious attacks We use software sensor objects which consist of sensor file for each important directory and sensor data for each secret file. Every sensor object is a sort of trap against the attack and it's touch tan be considered as an intrusion. The proposed system is a new challenge of setting up traps against most interception threats that try to copy or read illicitly programs or data. We have implemented the proposed system on the Linux operating system using loadable kernel module technique. The proposed system combines host~based detection approach and network-based one to achieve reasonably complete coverage, which makes it possible to detect unknown interception threats.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.2
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• pp.415-420
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• 2010

This paper describes the design overview of shared file system $SANique^{TM}$ and analyzes the performance evaluation results of I/O intensive stress test based on various cluster file system architectures. Especially, we illustrate the performance analysis for the comparison results between the $SANique^{TM}$ and the Linux file system EXT3 system that is used to generally in Unix world. In order to perform our evaluation, Oracle 10g database system is operated on the top of cluster file system, and we developed the various kinds of testing tools which are compiled by ESQL/C from Oracle. Three types of architectures are used in this performance evaluation. Those are the cluster file system $SANique^{TM}$, EXT3 and the combined architecture of $SANique^{TM}$ and EXT3. In this paper, we present that the results of $SANique^{TM}$ outperforms other cluster file systems in the overhead for providing the true sharing over the connecting server nodes.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10c
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• pp.6-11
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• 2007

방대한 양의 데이터를 처리하는 요구가 증가하면서 그로부터 유용한 정보를 추출해낼 수 있는 방법에 대한 필요성이 증가하고 있다. 메타데이터(metadata)를 관리하는 파일 시스템은 이러한 일을 빠르고 효과적으로 수행할 수 있는 방법 중 하나이다. 본 논문에서는 통합적인 메타데이터 관리를 가능하게 하고, 임베디드(embedded) 환경으로도 확장이 가능한 새로운 파일 시스템을 제안한다. 이를 위해 기존 리눅스(Linux) 파일 시스템을 바탕으로 새로운 파일 시스템을 설계하고 제시한다. 이렇게 설계된 파일 시스템은 사용자와 응용 프로그램에게 데이터의 다양한 뷰(view)를 제공할 수 있고 시스템 상에 존재하는 많은 양의 데이터를 통합하여 효율적으로 관리 할 수 있다.

• Journal of the Institute of Convergence Signal Processing
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• v.14 no.3
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• pp.181-190
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• 2013

In this paper, we designed file system in order to utilize data analysis by using correlation result from Daejeon correlator including related software development. Correlation results are consisted of visibility component (amplitude and phase) of radio source, but for data analysis of correlation result, various information such as weather, radio telescope position, observation time, radio source position, source type, and receiver noise temperature are needed. In this paper, we designed file system as a directory-structure for making use of these informations at Linux system for analyzing data and developed software to make file system. To verify the effectiveness of designed file system and developed software, file system generation experiment is conducted, and then astronomers accepted that there is no severe problem for scientific analysis using designed file system.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.9
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• pp.527-535
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• 2004

Handling mixed workload in digital set-top box or streaming server becomes an important issue as integrated file system gets momentum as the choice for the next generation file system. The next generation file system is required to handle real-time audio/video playback while being able to handle text requests such as web page, image file, etc. Legacy file system provides only best effort I/O service and thus cannot properly support the QoS of soft real-time I/O. In this paper, we would like to present our experience in developing the file system which fan guarantee the QoS of multimedia stream. We classify all application I/O requests into two category: periodic I/O and sporadic I/O. The QoS requirement of multimedia stream could be guaranteed by giving a higher priority to periodic requests than sporadic requests. The proto-type file system(Qosfs) is developed on Linux Operating System.

• Convergence Security Journal
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• v.7 no.4
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• pp.123-131
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• 2007

Recently, various threat and security incident are occurred for unspecified individuals, and this problem increases as the rapid of information sharing through Internet. The using of Information Security System such as IDS, Firewall, VPN etc. makes this problem minimal. However, professional knowledge or skill is needed in that case, normal user can't operate the Information Security System. This paper designs and implements File Access Control Module(FACM) to use easily for normal user against malicious threats and attacks. The FACM can exclude from malicious threats and attacks based on operation system rather than detection of threats and attacks. The FACM is working not only Windows System but also Linux System, and the FACM has effect on access control, integrity and non-repudiation for a file with an access control over files on the each OS that are used by multi-user.

• Journal of Broadcast Engineering
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• v.6 no.3
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• pp.246-259
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• 2001

Due to recent rapid deployment of Internet streaming service and digital broadcasting service, the issue of how to efficiently support streaming workload in so called "Internet Home Appliance" receives prime interests from industry as well as academia. The underlying dilemma is that it may not be feasible to put cutting edge CPU, boards, disks and other peripherals into that type of device. The primary reason is its cost. Usually, Internet Home Appliances has its dedicated usage, e.g. Internet Radio, and thus it does not require high-end CPU nor high-end Va subsystem. The same reasoning applies to I/O subsystem. In Internet Home Appliances dedicated to handle compressed moving picture, it is not equipped with high end SCSI disk with fast rotational speed. Thus, it is mandatory to devise elaborate software algorithm to exploit the available hardware resources and maximize the efficiency of the system. This paper presents our experiences in the design and implementation of a new multimedia file system which can efficiently deliver the required disk bandwidth for a periodic I/O workload. We have implemented the file system on the Linux operating system, and examined itsperformance under streaming I/O workload. The results of the study show that the proposed file system exhibits superior performance than the Linux Ext2 file system under streaming I/O workload. The result of this work not only contribute to advance the state f art file system technology for multimedia streaming but also put forth the software which is readily available and can be deployed. deployed.