• Proceedings of the Korea Information Processing Society Conference
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• 2020.05a
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• pp.63-65
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• 2020

과학응용분야의 원활한 협업 지원을 위해서는 원거리간 대용량 연구데이터의 고속 전송이 반드시 요구된다. 이와 관련하여, 본 논문은 기 구축된 대용량 파일 시스템을 다수의 데이터 전송 노드(DTN)에 연동하기 위해 필요한 요구사항들을 정리하고, 이에 기반하여 DTN 클러스터를 설계하고 구축한 사례를 제시한다. 추가적으로, 종단간 왕복지연 시간이 약 130ms에 달하는 원거리 종단 포인트와 대용량 실험데이터를 송수신함으로써 구축된 결과물의 전송 성능을 측정하고 확인한다.

• Journal of KIISE
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• v.42 no.6
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• pp.691-698
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• 2015

Application launch time is an important performance metric to user experience in desktop and laptop environment, which mostly depends on the performance of secondary storage. Application launch times can be reduced by utilizing solid-state drive (SSD) instead of hard disk drive (HDD). However, considering a cost-performance trade-off, utilizing SSDs as caches for slow HDDs is a practicable alternative in reducing the application launch times. We propose a new SSD caching scheme which migrates data blocks from HDDs to SSDs. Our scheme operates entirely in the file system level and does not require an extra layer for mapping SSD-cached data that is essential in most other schemes. In particular, our scheme does not incur mapping overheads that cause significant burdens on the main memory, CPU, and SSD space for mapping table. Experimental results conducted with 8 popular applications demonstrate our scheme yields 56% of performance gain in application launch, when data blocks along with metadata are migrated.

• Journal of Convergence for Information Technology
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• v.10 no.5
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• pp.23-29
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• 2020

These days, digital forensic technologies are being used frequently at crime scenes. There are various electronic devices at the scene of the crime, and digital forensic results of these devices are used as important evidence. In particular, the user's action and the time when the action took place are critical. But there are many limitations for use in real forensics analyses because of the short cycle in which user actions are recorded. This paper proposed an efficient method for recovering deleted user behavior records and applying them to forensics investigations, then the proposed method is compared with previous methods. Although there are difference in recovery result depending on the storage, the results have been identified that the amount of user history data is increased from a minimum of 6% to a maximum of 539% when recovered user behavior was utilized to forensics investigation.

• Journal of Korea Multimedia Society
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• v.15 no.8
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• pp.1048-1058
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• 2012

This paper proposes the DDMPF(Distributed Data Management Protocol using FAT) which prevents data loss and keeps the security of self-organized storages by comprising a client, a storage server, and a verification server in clouding environment. The DDMPF builds a self-organized storage server, solves data loss by decentralizing the partitioned data in it in contrast to the centralized problem and the data loss caused by the storage server problems of existing clouding storages, and improves the efficiency of distributed data management with FAT(File Allocation Table). And, the DDMPF improves the reliability of data by a verification server's verifying the data integrity of a storage server, and strengthens the security in double encryption with a client's private key and the system's master key using EC-DH algorithm. Additionally, the DDMPF limits the number of verification servers and detects the flooding attack by setting the TS(Time Stamp) for a verification request message and the replay attack by using the nonce value generated newly, whenever the verification is requested.

• Journal of KIISE
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• v.42 no.6
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• pp.723-733
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• 2015

The OTT service that provides multimedia video has spread over the Internet for terminals with a variety of resolutions. The terminals are in communication via a networks such as 3G, LTE, VDSL, ADSL. The service of the network has been increased for a variety of terminals giving rise to the need for a new way of encoding multimedia is increasing. SVC is an encoding technique optimized for OTT services. We proposed an efficient multimedia management system for the SVC encoded multimedia data. The I/O trace was generated using a zipf distribution, and were comparatively evaluated for performance with the existing system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.9
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• pp.2040-2048
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• 2010

In contemporary society, though convenience and efficiency of work using information system is growing high, adverse effect problems of malignant code, system hacking, information leak by insiders due to the development of the network are raising their head daily. Because of this, enormous work forces and expenses for the recovery and management of system is needed. The existing system can be divided into two aspects: security solution which surveils and treats virus and malignant codes, and network management solution which observes the system of computer, and practices maintenance and repair such as management, recovery, backup. This treatise applied Active Write Filter mechanism and the technology based on NFS and complemented the maintenance problems of user data of the existing system and designed the system which enables solving problems of intellectual property right such as information protection and illegal work.

• Journal of KIISE:Computer Systems and Theory
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• v.37 no.6
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• pp.330-338
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• 2010

Flash storage devices are very popularly used in portable devices such as cell phones, PDAs and MP3 players. As technology is improved, users want much bigger and faster storage system. Paradoxically, people have to wait more and more time proportionally to the capacity of their storage devices when these are trying to be recovered after file system crash. It is serious problem because booting time of devices is dominated by crash recovery of flash file system. In this paper, we design a crash recovery mechanism, named 'Working Area(WA hereafter)' technique, which has bounded crash recovery execution time. With WA technique, write operations to flash memory are only performed in WA. Therefore, by simply scanning the latest WA. We can recover a file system crash because every change for flash memory is occured only in latest WA. We implement the WA technique based on YAFFS2 and evaluate by comparing with traditional techniques. As a result, WA technique shows that its crash recovery execution time is 25 times faster than Log-based Method when we use 1 gig a bytes NAND flash memory in worst case. This gap will be futher and futher as storage capacity grows.

• Journal of the Institute of Convergence Signal Processing
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• v.17 no.2
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• pp.53-60
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• 2016

In this paper, we introduce the implementation and test results of a new method of correlated result storage to achieve the full performance of the Daejeon hardware correlator. Recently, the observation of 8 Gbps speed, which is the maximum observational standard of KVN(Korean VLBI Network), has been performed. The correlation processing using the Daejeon hardware correlator is also required. Therefore, a new correlation result storage introduction has become necessary. The maximum correlation result output speed of the Daejeon hardware correlator is 1.4 GB/sec per 25.6 ms integration time. The conventional correlation result storage system can not cope with the maximum correlation output speed of the Daejeon hardware correlator, and the output speed is limited to 1/4. That is, among the four input ports of the Daejeon hardware correlator, the three inputs are limited to correspond to the observation rate of 1 Gbps. This new storage system uses the Gluster file system among many of the latest technologies used in storage systems. In tests that meet the maximum output rate of 1.4 GB/sec for the Daejeon hardware correlator, 350 MB/sec for each of the four optical outputs, resulting in 1.4 GB/sec in total.

• Journal of the Korean Society for information Management
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• v.40 no.1
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• pp.149-173
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• 2023

This study examines email records management patterns of undergraduate students and their perceptions of university email policy. The research collected data from 317 undergraduate students using a survey based on the five essential elements of email records management: common elements, email creation, email management, email preservation, and perception. Also, an in-depth interview was conducted with 6 undergraduate students, according to the method of university email service: Google, Microsoft, and in-house webmail. As a result, undergraduate students used email as an address book, cloud storage, file storage, and collaboration tool, and they had difficulties in systematically managing the email records according to the records lifecycle. Also, there was a tendency to prefer using an external email platform that can use additional functions to in-house webmail that has limitations in mobile service and preservation of attachments. Thus, this study suggests ways to help undergraduate students manage their email records, including maintaining graduates' email accounts, providing sufficient email storage, and providing email records management training and guidelines for undergraduate students.

• Proceedings of the Korean Information Science Society Conference
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• 2010.06b
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• pp.368-373
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• 2010

플래시 메모리의 집적도가 높아지고 가격이 저렴해 짐에 따라 낸드 플래시 기반의 SSD의 사용이 확산 되고 있다. 플래시 메모리 기반 SSD는 기존의 하드디스크와 비교하여 여러 가지 장점을 가지지만 덮어 쓰기가 불가능한 특성상 쓰기 공간 확보를 위해 가비지 컬렉션이 수행되어야 하는 단점을 가진다. 이러한 단점을 개선하기 위해 다양한 연구들이 제안되었다. 이 중, 운영체제의 페이지 캐시에 대한 연구가 상반된 주장을 보이고 있는 점[11, 12, 13]에 착안하여 실험을 통해 이를 재확인하였다. 실험 결과, 큰 용량의 페이지 캐시가 SSD를 스토리지로 갖는 시스템에서 파일 입출력 성능을 크게 향상시키는 것을 확인 할 수 있었다.