• Journal of KIISE:Computer Systems and Theory
• /
• v.32 no.2
• /
• pp.68-74
• /
• 2005

In deadline scheduling, jobs have deadlines by which they are completed. The scheduling algorithm determines which jobs are executed at each time. Then only the completed jobs contribute to the throughput or gain of the algorithm. The jobs have arbitrary weights and the gain of the algorithm is given as the sum of weights of the completed jobs. The goal of the scheduling algorithm is to maximize its gain. In this paper, we consider online non-preemptive scheduling, where jobs arrive online and the scheduling algorithm has no information about jobs arriving ahead. Also the jobs cannot be preempted or rejected while they are executed. For this problem, we obtain lower bounds for any online algorithms and also we propose an optimal online algorithm meeting the lower bounds.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.48 no.1
• /
• pp.26-32
• /
• 2011

It is very important for more effective military operation to share information required in recognizing a situation by monitoring battlefield. The recognition of situations is offered visually though multi-media systems such as a COP(Common Operation Picture), UAV etc. The operating method has rapidly changed into Network-Centric Warfare (NCW). As a result, the data that these Multimedia systems should control is increasing. Improved performance of Multimedia systems is required to deal with them. In this paper, we propose Extended-Military Multimedia System(E-MMS) applying the most excellent scheduling method in terms of meet-ratio in real time when Multimedia systems carry out assigned information in real time for monitoring as the method of improved performance. As a result of utility about proposed system, it is verified that realtime EDF(Earliest Deadline First) scheduling method is more improved up to 20% compared to non-realtime FCFS(First Come First Service) in terms of the deadline meet ratio.

• Journal of Internet Computing and Services
• /
• v.6 no.2
• /
• pp.25-35
• /
• 2005

The Rate Monotonic(RM) scheduling algorithm and Earliest Deadline First(EDF) scheduling algorithm are normally used in Real-Time scheduling algorithm. In those scheduling algorithm, we could predict the performance possibility with total utilization value of task group. But. it had problems with prediction of the boundedness in individual task when the utilization value was over in temporary task. In this paper, the suggested scheduling algorithm can predict task when the utilization value was over and it suggested the method of predicting scheduling possibility based on the utilization value of individual task as well. it predicted the boundedness of scheduling possibility test through simulation In Real-Time scheduling algorithm and analyzed the result.

• Journal of the Korea Society of Computer and Information
• /
• v.7 no.2
• /
• pp.1-8
• /
• 2002

By now, Schedulers for RMS and EDF are implemented for real-time Linux Scheduler. These Schedulers are used for do not consider there's characteristics. Missing Schedulability-test cause result that increase deadline miss rate. Also The present real-time Linux causes system halt Because of scheduling for unschedulable tasks . These appearances are very fatal for real-time system. Therefor, In this paper The peaceful schedulability-test use scheduler which is proper characteristics of RMS and EDF scheduling methods. This scheduler keeps deadline and eliminates system halt from scheduling unschedulable tasks. In this paper, we propose the schedulability-test algorithm and scheduler select algorithm for the effective management of tasks sets.

• The KIPS Transactions:PartD
• /
• v.13D no.3 s.106
• /
• pp.399-404
• /
• 2006

A real-time system is used for various systems from small embedded systems to distributed enterprise systems. Because it has a characteristic that provides a service on time, developers should make efforts to keep this property about time when developing real-time applications. As the result of research about real-time system indicates, TMO model supports various functions for time processing according to the real-time concept. And it guarantees response time which developers defined. So developers need a point of reference to define deadline and check the correctness of time. This paper proposes an improved PS-Block as an infrastructure of analysis tools for TMO to present a point of reference. There is a problem that the existing PS-Block has overhead caused by a policy making duplicated blocks. As such, this paper implements a PS-Block Timing Model to reduce the overhead due to block duplication, and defines a base class for searching in PS-Block. The PS-Block Timing Model, using an improved PS-Block structure, offers a point of reference of deadline and an infrastructure of execution time analysis according to the PS-Block configuration policy. Therefore, TMO developers can easily verify deadline of real-time methods, and improve reliability, and reduce development terms.

• Convergence Security Journal
• /
• v.4 no.3
• /
• pp.57-82
• /
• 2004

The confluence of computers, communications, and databases is quickly creating a distributed database where many applications require real-time access to temporally consistent sensor data. We have developed an object-oriented real-time database system called BeeHive to provide a significant improvement in performance and functionality over conventional non-real-time database and object management systems. In this paper, the performance of two data-deadline cognizant scheduling policies EDDF and EDF-DC and the baseline EDF policy with/without admission control are evaluated through extensive experiments on BeeHive. The ranges where data-deadline cognizant scheduling policies are effective and where admission control plays a role are identified.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.12 no.2
• /
• pp.579-603
• /
• 2018

In this paper we propose a QoS-enhanced intelligent stochastic optimal fair real-time packet scheduler, QUEST, for 4G LTE traffic in routers. The objective of this research is to maximize the system QoS subject to the constraint that the processor utilization is kept nearly at 100 percent. The QUEST has following unique advantages. First, it solves the challenging problem of starvation for low priority process - buffered streaming video and TCP based; second, it solves the major bottleneck of the scheduler Earliest Deadline First's failure at heavy loads. Finally, QUEST offers the benefit of arbitrarily pre-programming the process utilization ratio.Three classes of multimedia 4G LTE QCI traffic, conversational voice, live streaming video, buffered streaming video and TCP based applications have been considered. We analyse two most important QoS metrics, packet loss rate (PLR) and mean waiting time. All claims are supported by discrete event and Monte Carlo simulations. The simulation results show that the QUEST scheduler outperforms current state-of-the-art benchmark schedulers. The proposed scheduler offers 37 percent improvement in PLR and 23 percent improvement in mean waiting time over the best competing current scheduler Accuracy-aware EDF.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.48 no.5
• /
• pp.650-657
• /
• 1999

In this paper, a real-time communication method using a PICNET-NP(Plant Instrumentation and Control Network for Nuclear Power plant) is proposed with an analysis of the control network requirements of DCS(Distributed Control System) in unclear power plants. The method satisfies deadline in case of worst data traffics by considering aperiodic and periodic real-time data and others.

• The Journal of the Korea Contents Association
• /
• v.13 no.10
• /
• pp.27-36
• /
• 2013

Recently, as researches on VANET have actively progressed, the convenient and reliable services can be provided to the vehicles. In this paper, we propose the collaborative RSU scheduling scheme using multiple RSUs which are connected through a wired backbone. The proposed scheme efficiently disseminates both unsafety data and safety data, and reduces the deadline miss rate and the average response time. When safety data is occurred, it is send to previous RSU in advance and is scheduled by deadline and reception rate. We provide the prevention technology for unsafety data when the workload is occurred in RSU because it is on-demand data processed by user requests. It is shown through performance evaluation that the proposed scheme outperforms the existing scheme in terms of the deadline miss rate and the average response time according to the number of vehicles and the velocities of vehicles.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.12 no.3
• /
• pp.1-7
• /
• 2012

Cognitive radio, a new paradigm for wireless communication, is being recently expected to support various types of multimedia traffics. To guarantee Quality of Service (QoS) from SUs, a static packet priority policy can be considered. However, this approach can easily satisfy Quality of Service of high priority application while that of lower priority applications is being degraded. In the paper, we propose a fuzzy-based dynamic packet scheduling algorithm to support multimedia traffics in which the dynamic packet scheduler modifies priorities of packets according to Fuzzy-rules with the information of priority and delay deadline of each packet, and determines which packet would be transmitted through the channel of the primary user in the next time slot in order to reduce packet loss rate. Our simulation result shows that packet loss rate can be improved through the proposed scheme when overall traffic load is not heavy.