• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.11
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• pp.34-39
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• 2009

In this study, we have proposed the random function arbitration method using a random function manager in other to use the merits and overcome the demerits of fixed priority and round-robin, Starvation phenomenon can be generated from the master having low priority in fixed priority method. Also, round-robin method can't give a priority to important master, however, as the proposed random function arbitration method can be random set the rate of fixed priority and round-robin, we can solve the problems of conventional arbitration methods. From TLM simulation, we confirmed that the bus utilization of master could be controled from 32% to 16% and the starvation phenomenon of master could be prevented.

• Proceedings of the Korea Society for Simulation Conference
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• 1997.04a
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• pp.93-99
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• 1997

Most of the past studies on FMS scheduling problems may be classified into two classes, namely off-line scheduling and on-line scheduling approach. The off-line scheduling methods are used mostly for FMS planning purposes and may not be useful real time control of FMSs, because it generates solutions only after a relatively long period of time. The on-line scheduling methods are used extensively for dynamic real-time control of FMSs although the performance of on-line scheduling algorithms tends vary dramatically depending on various configurations of FMS. Current study is about finding a better on-line scheduling rules for FMS operations. In this study, we propose a method to create priority functions that can be used in setting relative priorities among jobs or machines in on-line scheduling. The priority functions reflect the configuration of FMS and the user-defined objective functions. The priority functions are generated from diverse dispatching rules which may be considered a special priority functions by themselves, and used to determine the order of processing and transporting parts. Overall system of our work consists of two modules, the Priority Function Evolution Module (PFEM) and the FMS Simulation Module (FMSSM). The PFEM generates new priority functions using input variables from a terminal set and primitive functions from a function set by genetic programming. And the FMSSM evaluates each priority function by a simulation methodology. Based on these evaluated values, the PFEM creates new priority functions by using crossover, mutation operation and probabilistic selection. These processes are iteratively applied until the termination criteria are satisfied. We considered various configurations and objective functions of FMSs in our study, and we seek a workable solution rather than an optimum or near optimum solution in scheduling FMS operations in real time. To verify the viability of our approach, experimental results of our model on real FMS are included.

• KIISE Transactions on Computing Practices
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• v.23 no.8
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• pp.510-515
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• 2017

It is important to speed up the loading time of web applications. Parsing is a loading process that contributes to an increased loading time. To address this issue, the optimization called Concurrent Parsing has been proposed which handles the parsing process in parallel by using additional threads. However, Concurrent Parsing has a limitation that it does not consider the priority order of parsing. In this paper, we propose heuristics that exploit priorities of parsing to improve the Concurrent Parsing. For parsing priority, we empirically investigate the sequence of function calls, classify functions into 3 categories, and extract function call probabilities. If a function has high call probability, we give a high priority and if a function has low probability, we give a low priority. We evaluate this priority heuristics on real web applications and get the 2.6% decrease of loading time on average.

• Journal of applied mathematics & informatics
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• v.31 no.1_2
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• pp.147-154
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• 2013

We analyze queueing model with priority scheduling by supplementary variable method. Customers are classified into two types (type-1 and type-2 ) according to their characteristics. Customers of each type arrive by independent Poisson processes, and all customers regardless of type have same general service time. The service order of each type is determined by the queue length of type-1 buffer. If the queue length of type-1 customer exceeds a threshold L, the service priority is given to the type-1 customer. Otherwise, the service priority is given to type-2 customer. Method of supplementary variable by remaining service time gives us information for queue length of two buffers. That is, we derive the differential difference equations for our queueing system. We obtain joint probability generating function for two queue lengths and the remaining service time. Also, the mean queue length of each buffer is derived.

• Journal of applied mathematics & informatics
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• v.12 no.1_2
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• pp.291-297
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• 2003

This paper considers discrete-time two-class Ge $o^{X/}$G/1 queues with preemptive repeat priority. Service times of messages of each priority class are i.i.d. according to a general discrete distribution function that may differ between two classes. Completion times are derived for the preemptive repeat identical and different priority disciplines. By using the completion time, the stability condition for our system is investigated.d.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.6
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• pp.63-68
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• 2009

Most of agricultural reservoirs in Korea have no function of flood control except 5% of reservoirs even exposed to natural disaster. In addition, there are increasing needs for the reservoir to guarantee the release of environmental flow to the downstream. Thus, the purpose of this paper is to study the priority decision method for the reservoir redevelopment satisfying both water utilization and flood control. The major scopes of this research are to set up six priority indices and to make needed GIS data for calculating each priority. There is important consideration of obtaining the data or not in deciding the indices. Although the detailed indices is expected to better reflect redevelopment priority but the subjective indices like, 'opinion' and 'landscape' are excluded. From the results, it will enables the six priority indices to really assist in decision redevelopment priority of agricultural reservoirs.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.6
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• pp.107-115
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• 1998

A path planning using potential field method is very useful for the real-time navigation of mobile robots. However, the method needs high modeling cost to calculate the potential field because of complex preprocessing, and mobile robots may get stuck into local minima. In this paper, An efficient path planning algorithm for multiple mobile robots, based on the potential field method, was proposed. In the algorithm. the concepts of subgoals and obstacle priority were introduced. The subgoals can be used to escape local minima, or to design and change the paths of mobile robots in the work space. In obstacle priority, all the objects (obstacles and mobile robots) in the work space have their own priorities, and the object having lower priority should avoid the objects having higher priority than it has. In this paper, first, potential based path planning method was introduced, next an efficient collision-avoidance algorithm for multiple mobile robots, moving in the obstacle environment, was proposed by using subgoals and obstacle priority. Finally, the developed algorithm was demonstrated graphically to show the usefulness of the algorithm.

• Asia pacific journal of information systems
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• v.8 no.1
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• pp.27-42
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• 1998

In a competitive environment, selecting and effectively pursing the right information system investments can be a key factor in sustaining corporate viability and prosperity. This study applies quality function deployment(QFD) to the determination of information system development priority. The intent of QFD is to incorporate the needs of a customer through the various stages of product planning and manufacturing into a final product. The basic idea of our study is to translate the core competence and the competitive environment into the business strategy, and the critical success factors, and subsequently into information system development priority. Our method is applied to a motor company for the determination of the information system development priority. The company case is illustrated step by step with real data of the company and motor market.

• Journal of applied mathematics & informatics
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• v.22 no.1_2
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• pp.453-460
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• 2006

A discrete-time priority queueing system with place reservation discipline is studied, in which two different types of packets arrive according to batch geometric streams. It is assumed that there is a reserved place in the queue. Whenever a high-priority packet enters the queue, it will seize the reserved place and make a new reservation at the end of the queue. Low-priority arrivals take place at the end of the queue in the usual way. Using the probability generating function method, the joint distribution of system state and the delay distribution for each type are obtained.

• Journal of Communications and Networks
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• v.7 no.3
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• pp.313-324
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• 2005

The success of the IEEE 802.11 standard has prompted research into efficiency of the different medium access methods and their support for different traffic types. A modified version of the point coordination function (PCF) called modified PCF has been introduced as a way to improve the efficiency over the standard method. It has been shown through a simulation study and a mathematical analysis that channel utilization can be much improved compared to the standard, in case there is no so-called hidden station problem. However, under the hidden station problem, the efficiency of the modified PCF would obviously decrease. In this paper, some enhancements of the modified PCF are introduced. Firstly, we propose a retransmission process to allow frames involved in collisions to be retransmitted. Then, we propose a collision resolution mechanism to reduce the frame collision probability due to the hidden station problem. In addition, we propose a priority scheme to support prioritization for different traffic types such as interactive voice and video, and real-time data traffic in the modified PCF. To prevent the starvation of one low priority traffic, minimum transmission period is also guaranteed to each traffic type via an admission control algorithm. We study the performance of the modified PCF under the hidden station problem and the performance of the modified PCF with priority scheme through simulations. To illustrate the efficiency of the priority scheme, we therefore compare its simulation results with those of some standardized protocols: The distributed coordination function (DCF), the enhanced distributed channel access (EDCA), the PCF, and our previously proposed protocol: The modified PCF without priority scheme. The simulation results show that the increment of delay in the network due to the hidden station problem can be reduced using the proposed collision resolution mechanism. In addition, in a given scenario the modified PCF with priority scheme can provide better quality of service (QoS) support to different traffic types and also support a higher number of data stations than the previous proposals.