• IEMEK Journal of Embedded Systems and Applications
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• v.5 no.3
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• pp.128-135
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• 2010

Recently complexity of embedded software cause to be used real-time operating system (RTOS) to implement various functions in the embedded system. And also, according to requirement of complex functions in embedded systems, the number as well as complexity of tasks get increased continuously. In case that many tasks collaborated in a microprocessor, context switching time between tasks is a overhead waisting a CPU resource. Therefore the time of task context switching is an important factor that affects performance of RTOS. In this paper, we concentrate on the improvement of task context switch for reducing overhead and achieving fast response time in RTOS. To achieve these goal, we suggest multiple register files and task context switching algorithm. By reducing the context switch overhead, we try to ease scheduling and assure fast response times in multitasking environment. As a result, the context switch overhead decreased by 8~16% depend on the number of register files, and some task set which are not schedulable with single register file are schedulable due to that decrease with multiple register files.

• The Transactions of the Korea Information Processing Society
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• v.4 no.3
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• pp.639-648
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• 1997

As the areas of computer application are expanded, the real-time applicition enviroments that must process as many transactions as possible within their deadlines have been increased recently. Conventional disk based databaes system is not appropriate in real-time transaction processing due to delying time for disk I/O processing. When the system is overloaede, the performance of transaction scheduling technique using earliest deadline first deteriorates rapidly because it can assign the highest priority ot a transaction that has already missed or is about to miss tis deadline. Therfore, the performance of suggested transaction secheduling technique is made to improved by propos-ing the doule locking mechanism based on priority. Finally, in order to evaluate the performance of the proposed priority-based double locking techniques under single proessor and main memory database system environments, the simulation model was developed using the SLAM II language.

• The Transactions of the Korea Information Processing Society
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• v.6 no.11
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• pp.3124-3130
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• 1999

A duplex system enhances reliability by tolerating faults through spatial redundancy. Faults can be detected by duplicating identical tasks in pairs of modules. However, this kind of systems cannot even detect the fault if it occurs coincidently due to either malfunctions of common component such as power supply and clock or due to such environmental disruption as EMI. In the paper, we propose a method to reduce those effects of coincident faults in the duplex controller computer. Specifically, a duplex system tolerates coincident faults by using a sophistication sequencing of scheduling technique with certain timing redundancy. In particular when all tasks should be completed in the sense of real-time, the suggested scheduling method works properly to minimize the probability of faulty tasks due to coincident fault without missing the timing constraints.

• ETRI Journal
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• v.29 no.1
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• pp.120-123
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• 2007

In this letter, we address the problem of resource allocation with efficiency and quality of service (QoS) support in uplink for a wireless CDMA network supporting real-time (RT) and non-realtime (NRT) communication services. For RT and NRT users, there are different QoS requirements. We introduce and describe a new scheme, namely, traffic aided uplink opportunistic scheduling (TAUOS). While guaranteeing the different QoS requirements, TAUOS exploits the channel condition to improve system throughput. In TAUOS, the cross-layer information, file size information, is used to improve fairness for NRT users. Extensive simulation results show that our scheme can achieve high system throughput in uplink wireless CDMA systems, while guaranteeing QoS requirements.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.2 s.146
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• pp.228-235
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• 2006

Nowadays, digital manufacturing has been known to be very effective method in manufacturing fields. It is aimed to estimate process time, to improve operation efficiency, and to prevent bottleneck processes in advance of real manufacturing. This paper addresses a scheduling support system for panel hues in a shipyard through digital manufacturing simulation. The proposed system supports operators to make better decisions on the shop-floor scheduling in panel lines. It ,would provide a complete schedule that is at least as good as any schedule currently obtained. Furthermore, it can evaluate the operator's schedule by simulating it with 3-dimensional models before the work orders and schedules are released.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.438-440
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• 2004

Energy consumption has become an increasingly important consideration in designing real-time embedded systems. In this paper, we propose a voltage scaling method to reduce energy consumption in fixed priority real-time systems using variable voltage processors. The Hyperperiod of tasks is divided into dimains. The most suitable voltage of each domain is determined off-line and stored in a table. During task execution, the voltage of processor is adjusted according to the information of the table. A simulation result shows that the proposed method can reduce 80% of power consumption in comparison to no power management. The difference to the optimal EDF based method is only 5%.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.52-63
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• 2009

The problem of scheduling simply periodic task systems upon a uniform multiprocessor is considered. Partitioning of periodic task systems requires solving the bin-packing problem, which is known to be intractable (NP-hard in the strong sense). This paper presents a global scheduling algorithm which transforms a given simply periodic task system into another using a "task-splitting" technique. Each transformed simply periodic task system is guaranteed to be successfully scheduled upon any uniform multiprocessor using a partitioned scheduling algorithm. It is proven that the proposed algorithm achieves the theoretical maximum utilization bound upon any uniform multiprocessor platform.

• Journal of Computing Science and Engineering
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• v.8 no.1
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• pp.43-56
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• 2014

Semi-partitioned scheduling is a new approach for allocating tasks on multiprocessor platforms. By splitting some tasks between processors, semi-partitioned scheduling is used to improve processor utilization. In this paper, a new semi-partitioned scheduling algorithm called SS-DRM is proposed for multiprocessor platforms. The scheduling policy used in SS-DRM is based on the delayed rate monotonic algorithm, which is a modified version of the rate monotonic algorithm that can achieve higher processor utilization. This algorithm can safely schedule any system composed of two tasks with total utilization less than or equal to that on a single processor. First, it is formally proven that any task which is feasible under the rate monotonic algorithm will be feasible under the delayed rate monotonic algorithm as well. Then, the existing allocation method is extended to the delayed rate monotonic algorithm. After that, two improvements are proposed to achieve more processor utilization with the SS-DRM algorithm than with the rate monotonic algorithm. According to the simulation results, SS-DRM improves the scheduling performance compared with previous work in terms of processor utilization, the number of required processors, and the number of created subtasks.

• Journal of Korean Society for Quality Management
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• v.28 no.1
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• pp.196-209
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• 2000

In order to intensify an enterprise competition, quality inspection controls are very important issue. An organization or division of a company hopes which to acquire the quality inspection information be updated in real-time with respect to shop floor. In this paper, we develop a quality inspection control system for a Turbine/Generator production industry. The system compromises inspection scheduling module related to shop floor control (SFC) system, formal documentation control module, and formal inspection control module. In the quality inspection control system, ORACLE RDBMS is used for the database management system and ORACLE DEVELOPER 2000 is used for system development tool. The characteristic of this system is to support so it can enhance productivity and quality through inspection plans related to production scheduling.

• The KIPS Transactions:PartB
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• v.12B no.2 s.98
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• pp.173-180
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• 2005

In this paper, we propose an efficient real-time scheduling method of multimedia tasks for decoding frames of MPEG-2 video streams. In our task model, each frame is decoded by a separate multimedia task. The decoding task for each frame is assigned to the priority according to the precedence and importance of frames in a video stream. We use a priority-based scheduling policy in order to effectively allocate the CPU bandwidth to multimedia tasks for MPEG-2 decoding. We show how to dynamically control the fraction of the CPU bandwidth allocated to each multimedia task according to the priority. The primary purpose of our scheduling method is to enhance the real-time performance of the multimedia system by minimizing the number of decoding tasks that have missed their deadlines while reducing the decoding times of these multimedia tasks. The performance of this scheduling method is compared with that of similar mechanisms through simulation experiments.