• Communications for Statistical Applications and Methods
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• v.7 no.2
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• pp.489-497
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• 2000

The M/M/1 queue with impatient customers is studied. Impatient customers wait for service only for limited time K/0 and leave the system if their services do not start during that time. Notice that in the analysis of virtual waiting time, the impatient customer can be considered as the customer who enters the system only when his/her waiting time does not exceed K. In this paper, we apply martingale methods to the virtual waiting time and obtain the expected period from origin to the point where the virtual waiting time crosses over K or reaches 0, and the variance of this period. With this results, we obtain the expected busy period of the queue, the distribution, expectation and variance of the number of times the virtual waiting time exceeding level K during a busy period, and the probability of there being no impatient customers in a busy period.

• Journal of Korean Institute of Industrial Engineers
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• v.28 no.2
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• pp.187-192
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• 2002

In this paper we consider an M/G/1 queueing system with vacation. The length of vacation period may be controlled by the waiting time of the first customer. The server goes on vacation as soon as the system is empty, and resumes service either when the waiting time of the leading customer reaches a predetermined value, or when the vacation period is expired, whichever comes first. We consider two types of vacation, say, multiple vacation type and N-policy type. We derive the steady-state distributions of the number of customers at arbitrary time and arbitrary customer's waiting time by means of decomposition property. Also, the mean lengths of busy period, idle period and a cycle time are given.

• Journal of Information Technology Applications and Management
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• v.21 no.4
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• pp.15-33
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• 2014

Recently, the service providers are making various attempts to provide smartphone applications for waiting information in order for customers to perceive waiting time short. This research, therefore, investigates the impact of smartphone use on the waiting experience and provide service organizations with effective measures for managing customers' waiting. As a result of this study, utilization of smartphone during the waiting period shows the positive impact on perceived waiting time, acceptability, and emotional response. Among these, the largest impact appears on the acceptability of waiting that has the largest impact on the perceived service quality. In addition, results reveal that smartphone users shows more positive waiting experience than non-users who read newspapers or magazines, watch TV, or do nothing.

• Journal of the Korean Statistical Society
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• v.28 no.4
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• pp.523-533
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• 1999

We consider the M/G/1 queueing model with D-policy. The server is turned off at the end of each busy period and is activated again only when the sum of the service times of all waiting customers exceeds a fixed value D. We obtain the distribution of unfinished work and show that the unfinished work decomposes into two random variables, one of which is the unfinished work of ordinary M/G/1 queue. We also derive the distribution of queue waiting time.

• IE interfaces
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• v.25 no.3
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• pp.283-289
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• 2012

M/G/1 queue with server vacations period depending on the previous vacation and customer's arrival is considered. Most existing studies on M/G/1 queue with server vacations assume that server vacations are independent of customers' arrival. However, some vacations are terminated by some class of customers' arrival in certain queueing systems. In this paper, therefore, we investigate M/G/1 queue with server vacations where each vacation period has different distribution and vacation length is influenced by customers' arrival. Laplace-Stieltjes transform of the waiting time distribution and the distribution of number of customers waiting for each class of customers are respectively derived. As performance measures, mean waiting time and average number of customers waiting for each class of customers are also derived.

• Korea Journal of Hospital Management
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• v.8 no.2
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• pp.49-69
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• 2003

This study purported to evaluate the performance of the appointment system for outpatients in primary care dental clinic. The data of patients' time flow for 1,245 patients in Y Dental Clinic were collected for one month in 2002 and then analyzed. Specifically, the time periods of treatment and patients' waiting as well as rates of appointment and it's failure are estimated. The accuracy of expected treatment time period was also evaluated. The results showed that 72% of patients visited the clinic with appointments, and only 56% kept their appointments. The patient's waiting time period turned out to be 11 minutes in Y clinic. The expected treatment time period is turned out to be very important because they influence significantly on patient's waiting time period. Practically, the expected treatment time period should be overestimated about 9 minutes in general, and the characteristics of dentist, each patient's diagnosis and age need to be especially considered. Hospitals and clinics also need to make the systematic and detailed critical pathways for a variety of patient cases by analyzing the patients' treatment pattern. With the improved appointment systems, healthcare institutions will approach the goal of effective and efficient management of the institution and also satisfy their customers.

• Proceedings of the Korean Statistical Society Conference
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• 2004.11a
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• pp.289-294
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• 2004

We consider M/G/1 queue in which the customers are classified into n+1 classes by their impatience time. First, we analyze the model of two types of customers; one is the customer with constant impatience duration k and the other is patient customer. The expected busy period of the server and the limiting distribution of the virtual waiting time process are obtained. Then, the model is generalized to the one in which there are classes of customers according to their impatience duration.

• International Journal of Reliability and Applications
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• v.3 no.4
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• pp.165-171
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• 2002

An optimization of the M/M/1 queue with impatient customers is studied. The impatient customer does not enter the system if his or her virtual waiting time exceeds the threshold K ＞ 0. After assigning three costs to the system, a cost proportional to the virtual waiting time, a penalty to each impatient customer, and also a penalty to each unit of the idle period of the server, we show that there exists a threshold K which minimizes the long-run average cost per unit time.

• Journal of Korea Multimedia Society
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• v.9 no.2
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• pp.208-214
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• 2006

Participants of a NVE(networked virtual environment) may have different hardwares and network environments, and to guarantee the fairness, messages of participants should be synchronized. A solution for the synchronization problem is to wait for a certain amount of time until the server processes the message. It is not easy to determine a suitable waiting period because of the trade-off between the fairness and the responsiveness. In this paper we propose a method to decide a waiting period by considering only the participants with small network delays and perform experiments for the performance evaluation. Experiments show that the proposed method leads to significant improvement of responsiveness, while retaining fairness.

• Journal of Korea Game Society
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• v.5 no.4
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• pp.33-38
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• 2005

In the online game that thousands of participants connect to a game world by using Internet simultaneously, participants of the game world may have different hardwares and network environments, and messages of participants should be synchronization. A solution for the synchronization problem is to wait for a certain amount of time until the server processes the message. It is not easy to determine a suitable waiting period because of the trade-off between the fairness and the responsiveness. In this paper we propose a method to decide a waiting period by considering features of the MMOFPS game and the probability of interaction among participants. We implement the proposed method and perform experiments for the performance evaluation.