• Proceedings of the Korea Information Processing Society Conference
• /
• 2014.11a
• /
• pp.1215-1217
• /
• 2014

개인적인 용도의 파일을 저장하고 이를 여러 디바이스에서 공유하는 클라우드 서비스가 주목을 받고 있다. Dropbox와 OAuth, PACloud를 통해 이와 같은 서비스를 구현할 수 있다. 또한 스레드 폴링을 이용하여 서버에 들어오는 여러 태스크들을 적절하게 처리할 수 있는 구현 기술을 제시하였다. 구현 기술을 설명하기 위해 소프트웨어 공학적인 여러 다이어그램을 제시하였다.

• Proceedings of the Korea Multimedia Society Conference
• /
• 2003.05b
• /
• pp.57-60
• /
• 2003

최근 대부분의 기업 정보 범죄가 기업 내부자 소행으로 일어난다. 허가되지 않은 사용자의 불법적인 사용 및 도용은 기업 내부의 정보유출, 파괴 등 기업에 막대한 피해를 가져온다. 이런 환경에서 공용으로 사용되는 기업 정보에 대한 사용자별 파일 또는 디렉토리 접근에 대한 실시간적인 관리가 이루어져야 한다. 본 논문에서는 멀티 유저 윈도우서버의 디렉토리 및 파일에 접근하는 사용자를 실시간적으로 모니터링하고, 사용자 권한에 위배되는 행동을 모니터링하는 시스템을 설계 및 구현한다.

• Proceedings of the Korea Multimedia Society Conference
• /
• 2003.05b
• /
• pp.65-68
• /
• 2003

최근 웹 서버에 대한 해킹이 다양하고 지능적인 웜의 형태로 시도되고 있다 이러한 웹 서버 해킹은 대개 웹을 통하여 접근할 수 있는 취약성 파일에 악의적인 코드를 삽입하여 전파시킴으로써 웹서버에 피해를 주며 급속히 확산된다 따라서 이러한 취약성이 있는 파일을 조사할 수 있는 자동화된 도구가 요구되며, 본 논문에서는 웹으로 공유되어 있는 디렉토리 내에 웹 스캔을 이용하여 취약성 파일을 조사하는 방법으로 웹 서버 내의 취약성을 알아내는 분석도구를 개발하였다.

• Journal of Broadcast Engineering
• /
• v.23 no.4
• /
• pp.549-558
• /
• 2018

We designed and implemented streaming server based on MEPG DASH, which is able to provide high quality video with low-latency live streaming service like 360 VR video on the existing cable network via low-spec media service devices such as IPTV and OTT(Over the Top) SettopBox. We also designed and applied management process which is cable of supporting services by cashing streaming video file(MPD, Segment Files) to reduce the server response delay time. Further more, we confimred that it is also able to provide high quality of tiled video streaming with over 50,000kbps bitrate and 8K@60P through the experiment.

• Journal of the Korea Society for Simulation
• /
• v.16 no.2
• /
• pp.9-15
• /
• 2007

As the Internet grows and the mass multimedia data become popular, the storage system migrates from DAS, where the storage and the server are directly connected, to SAN and NAS. SAN connects the storages with a separate network, and NAS provides only file services, connects the storages with IP network. However, SAN and NAS can not fulfill the needs for companies if used separately, thus are asked to be integrated. In this research, we propose an efficient data sharing method which employees the concept of GMC, Croup Master Cache for the integrated environment of SAN and NAS. GMC is based on MCI, Metadata server and Cluster system Integration, but tries to solve the high expansion cost problem with MCI. We introduce the basic concept of GMC, compare the performance of GMC with that of MCI using computer simulation.

• Journal of Information Processing Systems
• /
• v.7 no.1
• /
• pp.53-62
• /
• 2011

With the steady growth of mobile technology and applications, demand for more storage in mobile devices has also increased. A lightweight block-level protocol, Internet Advanced Technology Attachment (iATA), has been developed to deliver a cost-effective storage network solution for mobile devices to obtain more storage. This paper seeks to contribute to designing and implementing Load Balancing (LB), Network Monitoring (NM) and Write Replication (WR) modules to improve the protocol's scalability and data availability. LB and NM modules are invoked to collect system resources states and current network status at each associate node (server machine). A dynamic weight factor is calculated based on the collected information and sent to a referral server. The referral server is responsible to analyze and allocate the most ideal node with the least weight to serve the client. With this approach, the client can avoid connecting to a heavily loaded node that may cause delays in subsequent in-band I/O operations. Write replication is applied to the remaining nodes through a WR module by utilizing the Unison file synchronization program. A client initially connected to node IP A for write operations will have no hindrances in executing the relevant read operations at node IP B in new connections. In the worst case scenario of a node crashing, data remain recoverable from other functioning nodes. We have conducted several benchmark tests and our results are evaluated and verified in a later section.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.18 no.3
• /
• pp.685-703
• /
• 2024

Cloud computing provides each consumer with a large-scale computing tool. Different Cyber Attacks can potentially target cloud computing systems, as most cloud computing systems offer services to many people who are not known to be trustworthy. Therefore, to protect that Virtual Machine from threats, a cloud computing system must incorporate some security monitoring framework. There is a tradeoff between the security level of the security system and the performance of the system in this scenario. If strong security is needed, then the service of stronger security using more rules or patterns is provided, since it needs much more computing resources. A new way of security system is introduced in this work in cloud environments to the VM on account of resources allocated to customers are ease. The main spike of Fog computing is part of the cloud server's work in the ongoing study tells the step-by-step cloud server to change the tremendous measurement of information because the endeavor apps are relocated to the cloud to keep the framework cost. The cloud server is devouring and changing a huge measure of information step by step to reduce complications. The Medical Data Health-Care (MDHC) records are stored in Cloud datacenters and Fog layer based on the guard intensity and the key is provoked for ingress the file. The monitoring center sustains the Activity Log, Risk Table, and Health Records. Cloud computing and Fog computing were combined in this paper to review data movement and safe information about MDHC.

• Journal of KIISE:Computer Systems and Theory
• /
• v.33 no.3
• /
• pp.193-204
• /
• 2006

In most existing distributed Web systems, incoming requests are distributed to servers via Domain Name System (DNS). Although such systems are simple to implement, the address caching mechanism easily results in load unbalancing among servers. Moreover, modification of the DNS is necessary to load considering the server's state. In this paper, we propose a new dynamic load balancing method using dynamic DNS update and round-robin mechanism. The proposed method performs effective load balancing without modification of the DNS. In this method, a server can dynamically be added to or removed from the DNS list according to the server's load. By removing the overloaded server from the DNS list, the response time becomes faster. For dynamic scheduling, we propose a scheduling algorithm that considers the CPU, memory, and network usage. We can select a scheduling policy based on resources usage. The proposed system can easily be managed by a GUI-based management tool. Experiments show that modules implemented in this paper have low impact on the proposed system. Furthermore, experiments show that both the response time and the file transfer rate of the proposed system are faster than those of a pure Round-Robin DNS.

• Journal of KIISE
• /
• v.44 no.4
• /
• pp.363-373
• /
• 2017

Ext4 file system is widely used in various computing environments such as those of the PC, the server, and the Linux-based embedded system. Ext4, which uses a buffer for block I/O, provides fsync() system call to applications to guarantee the consistency of a specific file. A log of the analytical studies regarding the operation of Ext4 and the improvement of its performance has been compiled, but it has not been studied in detail in terms of kernel versions. We figure out that the behavior of fsync() system call is different depending on the kernel version. Between the kernel versions of 3.4.0 and 4.7.2, 3.4.0, 3.8.0, and 4.6.2 showed behavioral differences regarding the fsync() system call. The latency of fsync() in kernel 3.4.0 is longer than that of the more-advanced 3.7.10; meanwhile, the characteristics of 3.8.0 enabled the disruption of the Ext4 journaling order, but the ordered defect was solved with 4.6.2.

• The Transactions of the Korea Information Processing Society
• /
• v.4 no.5
• /
• pp.1221-1230
• /
• 1997

In this study, the performance of a parallel file system(N-PFS), which is inplemented using conventional disks as disk arrays on a Workstation Cluster, is analyzed by using analytical method and adtual values in experiments.N-PFS can be used as high-performance file sever in small-scale server systems and effciently pro-cess massive data I/Os such as multimedia and scientifid data. In this paper, an analytical model was suggested and the correctness of the suggested was verified by analyzing the experimental values on a system.The result of the appropriate stping unit for processing massive data of the Workstation Cluster with 8 disks is 64-128Kbytes and the maximum throughput on it is 15.8 Mbytes/ses.In addition, the performance of parallel file system on massive data is bounded by the time required to copy data between buffers.