• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.884-887
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• 2002

This paper considers a scheduling problem of routers with VOQ(Virtual Output Queue)s, where the router has an N ${\times}$N port input-queued switch and each input queue is composed of N VOQs. The objective of the paper is to develope scheduling algorithms which minimize mean tardiness under a common due date. The paper characterizes the optimal solution properties. Based upon the characterization, a integer programming is formulated for the optimal solution and two optimal solution algorithms are developed for two special cases of 2 ${\times}$2 switch and N${\times}$N switch with identical traffic.

• Journal of the Korea Society of Computer and Information
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• v.7 no.3
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• pp.122-127
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• 2002

The Weighted Round Robin(na) discipline which is a sort of scheduling algorithm is quite simple and straightforward for handling multiple queues, and by Putting a different weight on each queue. In this paper, we propose new BSW structure, which can execute the WRR scheduling algorithm efficiently. Also, we develop a cell scheduling algorithm which is adapt in the new BSW structure. The Proposed BSW structure and the algorithm is capable of maintaining an allocated VC's weight correctly and decrease of average cell delay and maximum buffer length by serving other VC cell when empty in each VC queue. The proposed algorithm is a structure suitable for na implementation.

• Journal of the Korea Computer Industry Society
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• v.4 no.12
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• pp.1053-1068
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• 2003

In this paper, we propose a new scheduling method without timing covert channel of real-time transaction for secure database systems that implement mandatory access control. Our scheduling method use the wait queue based on security level to remove timing covert channel. And it use priority queue that consider transaction type, deadline, and weight. Therefore, the proposed scheduling method prevents timing covert channel because it is kept noninterference between transactions with different security level, and maximizes the sum of the weight of transactions that satisfy its deadline. The simulation results, is a comparison of traditional methods, show that our scheduling method is improved to 30%.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.4
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• pp.692-699
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• 2008

Semiconductor research and development(R&D) fabs are very different than production fabs in many ways such as the scales of production, job priority, production methods, and performance measures. Efficient operations of R&D fabs are very important to the development of new product, process stability, high yield, and ultimately company competitiveness. This paper proposes the fab-wide scheduling method for operational optimization of the R&D fabs. Most scheduling systems of semiconductor fabs have only focused on maximizing throughput of each separated areas without considering WIP(works in process) flows of entire fab. In this paper, we proposes the a fab-wide scheduling system which schedules all lots to entire fab equipment at once. We develop the MIP(mixed integer programing) model which allocates the lots to production equipment considering many constraints of all processes and the CP(constraint programming) model which determines the sequences of the lots in the production equipment. The proposed FAB-wide scheduling model is applied to the newly constructed R&D fab. As a result, we have accomplished the system based automated job reservation, decrease of the hot lot delay, increase of the queue time satisfaction, the high throughput by maximizing the batch sizes, decrease of the WIP TAT(Turn Around Time).

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.2
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• pp.279-287
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• 1993

In this paper, double laxity threshold MLT(Minimum Laxity Threshold) algorithm and double queue threshold QLT(Queue Length Threshold) algorithm are proposed as DPS(Dynamic Priority Scheduling) techniques for advanced processing of multiple class traffics. Also, the performance of the proposed algorithms is analyzed by a computer simulation. According to the simulation results, it can be shown that the proposed double laxity threshold ML T algorithm advances the processing performance versus ML T algorithm for 2 or more classes delay sensitive traffics, and that double queue length threshold QL T algorithm provides more efficient performance than QL T for 2 or more classes of non real time traffics.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.445-448
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• 2000

This paper considers a scheduling algorithm for high-speed routers, where the router has an N x N port input-queued switch and the input queues are composed of N VOQ(Virtual Output Queue)s at each input port. The major concern of the paper is on the scheduling mechanism for the router. The paper discusses the preferred levels of the performance measures and then develope a non-linear mixed integer programming. Additionally, the paper suggests a heuristic scheduling algorithm for efficient and effective switching.

• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.293-298
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• 2001

This paper propose the DoubleQ web server that classifies incoming requests according to whether the requested document is cached or not. Requests that demand a cached document is put into the Service Queue while other requests are added to the Defer Queue. The DoubleQ web server services requests that are in the Service Queue before it services requests in the Defer Queue. This strategy is used to reduce disk accesses that have been the predominant overhead of traditional web servers. Experimental results using synthetic data show that improvements in the average user response time and the throughput of the web server may be achieved.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.6
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• pp.337-343
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• 2006

The Stack Resource Policy (SRP) is a real-time synchronization protocol with some distinct properties. One of such properties is early blocking; the execution of a job is delayed instead of being blocked when requesting shared resources. If SRP is used with dynamic priority scheduling such as Earliest Deadline First (EDF), the early blocking requires that a scheduler should select the highest-priority job among the jobs that will not be blocked, incurring runtime overhead. In this paper, we analyze the runtime overhead of EDF scheduling when SRP is used. We find out that the overhead of job search using the conventional implementations of ready queue and job search algorithms becomes serious as the number of jobs increases. To solve this problem, we propose an alternative data structure for the ready queue and an efficient job-search algorithm with O([log$_2n$]) time complexity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.10
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• pp.1240-1243
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• 2016

In this paper, we analyze the queueing performance of cumulative distribution function (CDF)-based opportunistic scheduling over Nakagami-m Markov fading channels. We derive the formula for the average queueing delay and the queue length distribution by constructing a two-dimensional Markov chain. Using our formula, we investigate the queueing performance for various fading parameters.