• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.60.1-60
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• 2001

In recent years, distributed control systems(DCS) using fieldbus such as CAN have been being applied to process systems but it is very difficult to design the DCS in order to guarantee the given end-to-end constraints such as precedence constraints, time constraints, and periods and priorities of tasks and messages. This paper presents a scheduling method to guarantee the given end-to-end constraints. The presented scheduling method is the integrated one considering both tasks executed in each node and messages transmitted via the network and is designed to be applied to a general DCS that has multiple loops with several types of constraints, where each loop consists of ...

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.2
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• pp.230-237
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• 1987

This paper proposes a compatible variables scheduling algorithm, which is the process to pack variables into same register without modifying program semantics, for efficient register allocation of microprogram. The algorithm constructs T-V matrix, obtains incompatible variable set and scheduling priority, and schedules compatible groups. By this algorithm, the number of compatible groups can be minimized. The algorithm was implemented with C language on VAX-11/780 computer. By applying the algorithm to practical microprograms, the effectiveness of the algorithm is verified.

• The Transactions of the Korea Information Processing Society
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• v.3 no.4
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• pp.803-816
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• 1996

It is possible to prevent deadlock if the priority which is conventionally given to transactions is endowed to data items and the transactions with the highest priority among transactions accessing the data item is allowed to proceed. Based on this observation, we proposed a Data-Priority Based Locking Protocol(DPLP) and evaluated its performance against known locking protocols in Real Time Database Management System(RTDBMS). Transaction inter-arrival time(IAT) was varied to determine success ratio, average-lateness, confict ratio and restart ratio, In these simulations we verified that the proposed DPLP performs better than the other protocols.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.9
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• pp.39-48
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• 2008

Recently, many multimedia services have emerged in Internet such as real-time and non- real time services. However, in this Internet environment, we have some limitations to satisfy each service feature. To guarantee the service features in Measurement-Based Admission Control(MBAC) based system on the flow-aware network, there is the method applying Dynamic Priority Scheduling(DPS) algorithm that gives a higher priority to an earlier incoming flow in all of the link bandwidth. This paper classifies all flows under several groups according to flow characteristics on per-flow MBAC algorithm based system. In each flow group, DPS algorithm is applied. This paper proposes two methods that are a DPS based bandwidth borrowing method and a bandwidth dynamic allocation method. The former is that if low priority class has available bandwidths, the flow of high priority class borrows the bandwidth of low priority class when high priority flow has insufficient bandwidth to connect a flow call. The later is that the each group has a minimum bandwidth and is allocated the bandwidth dynamically according to the excess rate for available bandwidth. We compare and analyze the characteristics of the two proposed methods through the simulation experiments. As the results of the experiment, the proposed methods are more effective than existing DPS based method on the packet loss and delay characteristics. Consequently the proposed two methods are very useful in various multimedia network environments.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.70-73
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• 1998

This paper present a new priority control mechanism which is to balance the cell loss rate by measuring, in real time, the number of discarded cells in the queuing system with a different loss priority for each class of service such that each class of service meets its cell loss rate requirements. And, to reduce the delay rates we modified existing cell scheduling scheme. Throughout the computer simulation, the existing methods and proposed scheme is compared with respect to cell loss rate and average delay time. In the result of simulation, the proposed scheme have more improved performance than the other schemes with respect to cell loss rate and average delay time.

• The Journal of the Korea Contents Association
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• v.21 no.6
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• pp.12-18
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• 2021

A proportional share scheduler allocates CPU time to tasks and determines which task will be dispatched according to their priorities. In this paper, we investigate the correlation between the characteristics of applications and task priorities in the Linux Completely Fair Scheduler(CFS), which is one of the representative proportional share schedulers. We also propose a method of controlling the granularity of priority assignments according to the characteristics of applications. We implemented the proposed technique in a Linux system and confirmed the meaningful experimental results.

• The Transactions of the Korea Information Processing Society
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• v.5 no.11
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• pp.2973-2979
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• 1998

As this paper is a scheduling algorithm for the synthesis of a pipelined datapath under resource constraints in high level synthesis, the proposed heuristic algorithm uses a priority function based on the collision count of resourecs. In order to schedule the pipelined datapath under resource constraints, we define the collision count and the priority function based on the collision count, a number of resource, and the mobility of operations to resolve a resource collision. The proposed algorithm supports chaining, multicycling, and structural pipelining to design the realistic hardware. The evaluation of the Performance is compared with other systems using the results of the synthesis for a 16point FIR filter and a 5th order elliptic wave filter, where in most cases, the optimal solution is obtained.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.307-310
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• 2000

ATM is the switching and multiplexing technology chosen by the ITU-T for the operation of B-lSDN. Basically, ATM technology is designed to combine the reliability of circuit switching with the efficiency and flexibility of packet switching technology. For servicing QoS in IPOA(IP over ATM) when the larger effort is given, it will be the good method that the original QoS benefits having ATM switching have in ATM layer underlying layer. The IETF has recently proposed Differentiated Services framework for provision of QoS. In this paper we analyse performance of two Diffserv mechanism. Threshold Dropping and Priority Scheduling. Threshold Dropping and Priority Scheduling can be regarded as basic mechanisms from which the other mechanisms have been derived. Hence comparative performance of these two mechanisms in providing required QoS is an important issue. In this Paper we carry out a performance comparison of the TD and PS mechanisms with the aim of providing the same level of packet loss to the preferred flow. Our comparison of the TD and PS allows us to determine resultant packet loss for the non-preferred flows as a function of various parameters of the two mechanisms.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.10
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• pp.562-574
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• 2004

We address the problem of energy-optimal voltage scheduling for fixed-priority hard real-time systems. First, we prove that the problem is NP-hard. Then, we present a fully polynomial time approximation scheme (FPTAS) for the problem. for any $\varepsilon$>0, the proposed approximation scheme computes a voltage schedule whose energy consumption is at most (1+$\varepsilon$) times that of the optimal voltage schedule. Furthermore, the running time of the proposed approximation scheme is bounded by a polynomial function of the number of input jobs and 1/$\varepsilon$. Experimental results show that the approximation scheme finds more efficient voltage schedules faster than the best existing heuristic.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.3 s.345
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• pp.135-143
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• 2006

PQ(Priority Queue) and WRR(Weighted Round Robin) are the most famous schedulers, however, these schedulers have both points of advantages and disadvantages. In this paper, we propose an algorithm that can be adopted in my kind of scheduling type with making up for weak points of PQ and WRR. The proposed algorithm includes a fuzzy theory in the scheduler to assign priorities dynamically in the DiffServ network. This algorithm produces the control discipline by the fuzzy theory to assign priorities of the Queue effectively with checking the Queue status of each class dynamically under the discipline.