• Proceedings of the Korean Society of Computer Information Conference
• /
• 2018.07a
• /
• pp.15-16
• /
• 2018

본 논문에서는 다수의 센서 노드로 구성된 Internet of Things (IoT) 환경에서 새로운 환경에 대해 적응하는데 걸리는 시간을 줄이기 위한 새로운 스케줄링 기법을 제안한다. IoT 환경에서는 데이터 수집 및 전송 패턴이 사전에 정의되어 있지 않기 때문에 기존 정적인 Packet scheduling 기법으로는 한계가 있다. Q-learning은 네트워크 환경에 대한 사전지식 없이도 반복적 학습을 통해 Scheduling policy를 확립할 수 있다. 본 논문에서는 기존 Q-learning 스케줄링 기법을 기반으로 각 큐의 패킷 도착률에 대한 bound 값을 이용해 Q-table과 Reward table을 초기화 하는 새로운 Q-learning 스케줄링 기법을 제안한다. 시뮬레이션 결과 기존 기법에 비해 변화하는 패킷 도착률 및 서비스 요구조건에 적응하는데 걸리는 시간이 감소하였다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.9
• /
• pp.2213-2221
• /
• 2015

The ondemand governor used in android-based smartphone platforms is a CPU frequency scaling technique. The ondemand governor sets the CPU operating frequency depending on the CPU utilization rate. Job scheduling affects the CPU utilization rate. The power consumption is proportional to the value of operating frequency. Consequently, CPU frequency scaling and CPU utilization rate have an effect on power consumption in a smartphone. In this paper, we evaluated the performance of job scheduling techniques incorporating the ondemand governor in terms of CPU utilization, power consumption, and job deadline miss ratio.

• Journal of Korea Multimedia Society
• /
• v.17 no.10
• /
• pp.1189-1197
• /
• 2014

Recently, general purpose graphic processing units(GPUs) are being widely used in mobile embedded systems such as smart phone and tablet PCs. Because of architectural limitations of mobile GPGPUs, only a single program is allowed to occupy a GPU at a time in a non-preemptive way. As a result, it is difficult to meet performance requirements of applications such as frame rate or response time if applications running on a GPU are not scheduled properly. To tackle this difficulty, we propose to specify applications using synchronous data flow model of computation such that applications are formed with edges and nodes. Then nodes of applications are scheduled onto a GPU unlike conventional scheduling an application as a whole. This approach allows applications to share a GPU at a finer granularity, node (or task)-level, providing several benefits such as eliminating need for manually partitioning applications and better GPU utilization. Furthermore, any scheduling policy can be applied in response to the characteristics of applications.

• Journal of Preventive Medicine and Public Health
• /
• v.26 no.4 s.44
• /
• pp.650-660
• /
• 1993

This study aims to describe the causes of medically unnecessary hospital stay at a teaching tertiary hospital, using modified version of Delay Tool in which the causes of delay are divided into slx major categories : delay related to test scheduling, test results, surgery, medical staff, patient/family, and administration. For the analysis of hospital stay, 6,479 inpatient-days were reviewed in two medical and four surgical departments for one month. Initially inappropriate hospital stays were identified using Appropriateness Evaluation Protocol (AEP), and causes of delay listed in Delay Tool were assigned to each of them. In both medical and surgical services, the most important cause of delay was related to medical staffs, ranging from 3.6% to 51.6% of total inpatient days. Next important category was delay related to test scheduling in medical services ($4.7{\sim}9.2%$), and delay related to surgery in surgical services ($7.3{\sim}15.0%$). Among subcategories of delay related to medical staffs, delay due to conservative care was the most important cause of inappropriate hospital stay ($2.9{\sim}6.4%$). Each clinical departments had different distribution among delay categories, which could not be fully justified by their clinical charateristics. The Delay Tool would be helpful in exploring factors related to the inefficient use of hospital beds. As a measurement tool of inappropriate hospital stay, however, the Delay Tool should be refined in the definitions of categories and its contents.

• Journal of Korea Multimedia Society
• /
• v.13 no.9
• /
• pp.1285-1298
• /
• 2010

Since the TinyOS incorporating a non-preemptive task scheduling policy uses a FIFO (First-In First-Out) queue, a task with the highest priority cannot preempt a task with lower priority before the task with lower priority must run to completion. Therefore, the non-preemptive TinyOS cannot guarantee the completion of real-time user tasks within their deadlines. Additionally, the non-preemptive TinyOS needs to meet the deadlines of user tasks as well as those of TinyOS platform tasks called by user tasks in order to guarantee the deadlines of the real-time services requested by user tasks. In this paper, we present a group-based real-time scheduling technique that makes it possible to guarantee the deadlines of real-time user tasks in the TinyOS incorporating a non-preemptive task scheduling policy. The proposed technique groups together a given user task and TinyOS platform tasks called and activated by the user task, and then schedule them as a virtual big task. A case study shows that the proposed technique yields efficient performance in terms of guaranteeing the completion of user tasks within their deadlines and aiming to provide them with good average response time, while maintaining the compatibility of the existing non-preemptive TinyOS platform.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.11A
• /
• pp.1106-1112
• /
• 2007

As a demand for high speed uplink packet services increases, the WCDMA enhanced uplink, also known as high speed uplink packet access (HSUPA), has been specified in release 6 by 3GPP. This HSUPA will provide various types of multimedia services, such as real-time video streaming, gaming, VoIP, and FTP. Generally, the performance of HSUPA is dominated by scheduling policy. Therefore, it is required to design a scheduling algorithm considering the traffic characteristics to provide QoS guaranteed services in various traffic environments. In this paper, we propose a scheduling algorithm considering the traffic characteristics to guarantee QoS in a mixed traffic environment. Finally, the performance of the proposed scheduling algorithm is evaluated in terms of average packet delay, packet delay jitter, and system throughput using a system level simulator.

• Journal of Korea Multimedia Society
• /
• v.13 no.3
• /
• pp.349-358
• /
• 2010

Adaptability is an important issue in video streaming over mobile environments, since the clients may request videos with great differences in their workload. In this paper, we propose the issues in limited bandwidth scheduling for efficient MPEG-4 video stream transmission over a mobile or wireless network. In the phase of admission control, the amount of bandwidth allocated to serve a video request is the mean bandwidth requirement of its requested video. The dynamic allocation of bandwidth in the phase of scheduling depends on the playback buffer levels of the clients with an objective to make it more adaptive to the playback situation of individual clients. In the proposed RTA scheduling protocol, more bandwidth may be allocated temporarily to the client whose buffer level is low. By employing the buffer level based scheduling policy, this protocol attempts to maximize the real-time performance of individual playback while minimizing the impact of transient overloading. Extensive simulation experiments have been performed to investigate the performance characteristics of the RTA protocol as comparing with BSBA protocol. This RTA protocol shows the better performance by transferring more frames than BSBA protocol.Computer simulations reveals that the standard deviation of the bit rate error of the proposed scheme is 50% less than that of the conventional method.

• Journal of KIISE:Computer Systems and Theory
• /
• v.29 no.9
• /
• pp.520-529
• /
• 2002

This paper presents an approach for scheduling network messages with real-time dynamic algorithms. We present the method that calculates an intermediate relative deadline of the message based on the EDF(Earliest Deadline First) scheduling policy. We adjust the slack of message by using this intermediate relative deadline to allocate a priority of message. The priority of the message can be determined accurately by using the slack that calculates in our approach, which increases the schedulability efficiency of the message. As a result, we reduce the worst-case response time and improve the guarantee ratio of real-time messages. Also, we describe the analysis method to check the schedulability on message sets, and show the efficiency of our approach by comparing the results of the DM(Deadline Monotonic) approach and the existing EDF approach with that of the improved EDF in our approach through the simulation.

• Proceedings of the Korean Information Science Society Conference
• /
• 2008.06a
• /
• pp.377-378
• /
• 2008

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.1A
• /
• pp.44-53
• /
• 2010

This paper proposes a traffic management policy for delay control in the wireless networks. The so-called EDD(Earliest Due Date) scheme is adopted as the packet scheduling policy, so that the service provision is performed in the order of the transmission urgency of the backlogged packets. In addition, we derive a formula to determine the contention window, one of the MAC parameters, with the goal of minimizing the non-work conserving characteristics of the traditional MAC scheme. This method eliminates the burden of the class-wise parameter settings which is typically required for the priority control. Simulations are performed to show the validity of the proposed scheme in comparison with the policy that adopts the class-level queue management such as the IEEE 802.11e standard. Smaller delays and higher rates of delay guarantees are observed throughout the experiments.