• Journal of Information Technology Services
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• v.13 no.3
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• pp.201-219
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• 2014

This paper considers service deployment and priority optimization for multiple service-oriented applications sharing reusable services, which are deployed as multiple instances in the cloud. In order to handle variations in the workloads of the multiple applications, service instances of the individual reusable services are dynamically provisioned in the cloud. Also service priorities for each application in a particular reusable service are dynamically adjusted. In this paper, we propose an analytic performance model, based on a queueing network model, to predict the expected sojourn times of multiple service-oriented applications, given the number of service instances and priority disciplines in individual reusable services. We also propose a simple heuristic algorithm to search an optimal number of service instances in the cloud and service priority disciplines for each application in individual reusable services. A numerical example is also presented to demonstrate the applicability of the proposed performance model and algorithm to the proposed optimal decision problem.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.3
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• pp.66-75
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• 2017

Priority disciplines are an important scheme for service systems to differentiate their services for different classes of customers. (N, n)-preemptive priority disciplines enable system engineers to fine-tune the performances of different classes of customers arriving to the system. Due to this virtue of controllability, (N, n)-preemptive priority queueing models can be applied to various types of systems in which the service performances of different classes of customers need to be adjusted for a complex objective. In this paper, we extend the existing (N, n)-preemptive resume and (N, n)-preemptive repeat-identical priority queueing models to the (N, n)-preemptive repeat-different priority queueing model. We derive the queue-length distributions in the M/G/1 queueing model with two classes of customers, under the (N, n)-preemptive repeat-different priority discipline. In order to derive the queue-length distributions, we employ an analysis of the effective service time of a low-priority customer, a delay cycle analysis, and a joint transformation method. We then derive the first and second moments of the queue lengths of high- and low-priority customers. We also present a numerical example for the first and second moments of the queue length of high- and low-priority customers. Through doing this, we show that, under the (N, n)-preemptive repeat-different priority discipline, the first and second moments of customers with high priority are bounded by some upper bounds, regardless of the service characteristics of customers with low priority. This property may help system engineers design such service systems that guarantee the mean and variance of delay for primary users under a certain bounds, when preempted services have to be restarted with another service time resampled from the same service time distribution.

• Journal of the Korean Operations Research and Management Science Society
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• v.33 no.2
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• pp.115-135
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• 2008

An interesting problem in capacitated supply chains is how to guarantee customer service levels with limited resources. One of the common approaches to solve the problem is differentiating service depending on customer classes. High-priority customers receive a better service at the cost of low-priority customers' service level. One of common criteria to determine a customer's priority in practice is whether he has made a reservation before arrival or not. Customers with a reservation usually receive service based on the time the reservation was made. We examine the effect this advance information of customer arrival has on customer service levels. We show the trade-offs between the leadtime and other system characteristics such as the proportion of high-priority customers. when the service level is high. We also suggest how to differentiate service using the asymptotic ratio of the service levels for both types of customers.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.4
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• pp.1-14
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• 2020

Recently, M/G/1 priority queues with a finite buffer for high-priority customers and an infinite buffer for low-priority customers have applied to the analysis of communication systems with two heterogeneous traffics : delay-sensitive traffic and loss-sensitive traffic. However, these studies are limited to M/G/1 priority queues with finite and infinite buffers under a work-conserving priority discipline such as the nonpreemptive or preemptive resume priority discipline. In many situations, if a service is preempted, then the preempted service should be completely repeated when the server is available for it. This study extends the previous studies to M/G/1 priority queues with finite and infinite buffers under the preemptive repeat-different and preemptive repeat-identical priority disciplines. We derive the loss probability of high-priority customers and the waiting time distributions of high- and low-priority customers. In order to do this, we utilize the delay cycle analysis of finite-buffer M/G/1/K queues, which has been recently developed for the analysis of M/G/1 priority queues with finite and infinite buffers, and combine it with the analysis of the service time structure of a low-priority customer for the preemptive-repeat and preemptive-identical priority disciplines. We also present numerical examples to explore the impact of the size of the finite buffer and the arrival rates and service distributions of both classes on the system performance for various preemptive priority disciplines.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.2B
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• pp.11-20
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• 2005

Strict priority scheduling scheme is a good candidate for the implementation of service differentiation in an Internet because of simplicity in implementation and the capability to guarantee the delay requirement of the highest class of traffic. However, it is also blown that strict priority starves the lower-class traffic at the cost of prioritizing the higher-class traffic. The purpose of this work is to propose an analytic method which can estimate the average delay performance of Diffserv service architecture and shows that strict priority scheme does not sacrifice the lower class traffic over a diverse condition of the load. From the numerical experiments for three-class Diffserv network we validate our argument that strict priority scheme may be applied to a service differentiation scheme for the future Internet.

• Journal of IKEEE
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• v.7 no.2 s.13
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• pp.181-187
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• 2003

In high speed packet switching network, packet service by priority scheme prefer to QoS. Efficient packet service according to the priority scheme in high speed packet switch is a key point. Therefore development of priority service algorithm in the packet switch is very important. In this paper, we proposed W-iSLIP algorithm that service time take queue length into consideration and compared the proposed W-iSLIP algorithm to other previous proposed algorithm through simulation. Simulation results show 2.6% performance elevation in average delay, and 34.6% performance elevation in priority service.

• Journal of the Korean Association of Geographic Information Studies
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• v.11 no.2
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• pp.132-147
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• 2008

So far ubiquitous service (u-service) priority has seldom been empirically examined based on the customer's view. It is usual to prioritize the relative importance of u-service variables by the supplier's intuition and a few specialist's experienced knowledge. Such approaches have the disadvantage that they provide only limited empirical information on the field practices in relation to u-service since customer demand of u-service is poorly defined despite abundant interest in this problem. Therefore, the aim of this research was to develop u-service priority model in the context of multi-criteria framework integrating customer and supplier's view, using high technology acceptance theory as major controlling factors. An important question was how to measure or represent criteria that is important to u-service and should be included in a priority model. The selection criteria for the model variables were derived from high technology acceptance theory and AHP approach through the analysis of frequency count, elimination of overlapping factors and brainstorming with specialists. Daegu showed top-rankings in transportation-aid service, guidance service for the eyesight disabled and u-telematics service. In contrast, disaster prevention service and industrial specialized town service ranked highly in the typical supplier's approach were not a dominant determining factor in the u-service priority. The model identified the fact that typical high priority service in terms of supplier's view did not necessarily accompany the important predictor for the u-service priority.

• Journal of the Korea Safety Management & Science
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• v.18 no.4
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• pp.195-209
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• 2016

This research determined priority of quality improvement of public institution's education service by using ASC for importance and applying Topsis, a multi-standard decision-making method simplifying various attributes and scales of evaluation items and deciding the comparative priority for satisfaction and discussed the differences so as to measure the quality of public institution's educational service and examine the priority of education service' quality improvement. This research classified the characteristics of quality improvement. As a result, it's significant to suggest positive direction and method to improve satisfaction and education service's quality from an angle of demander by analyzing educational satisfaction of education service quality of public education institution and effects on the following improvement.

• The KIPS Transactions:PartC
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• v.16C no.2
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• pp.217-222
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• 2009

This paper proposes the number of Optical Network Unit (ONU) based priority scheduling mechanism over Ethernet Passive Optical Network (EPON) to support multicast Quality of Service (QoS) for Internet Protocol Television (IPTV) service. Multicast QoS is effected by the receivers' number of a packet because multicast efficiency is determined by how many receivers are received multiple copied packets. Therefore, the proposed mechanism assigns a priority with the number of ONUs to allocate high priority to IPTV services used by many people and firstly transmits a packet with high priority. By doing so, we show that the proposed mechanism support favorite IPTV services with better and stable QoS in spite of congestion.