• Journal of the Korean Institute of Rural Architecture
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• v.12 no.4
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• pp.29-36
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• 2010

The purpose of this study is to have detailed data of the distribution, locations, and the amount of people in the waiting line of the nursing home. Also, we studied the accessibility to the facilities by using Web GIS to analyze the transit time it takes from the nursing home to health center and hospitals. We can provide the basic data that could contribute when future plans for the nursing homes' locations, health and medical policy are made. The results are as follows. 1. The nursing homes are stiffly concentrated in regions of Seoul and Gyeongi-do where large number of the elderly covered by long-term care insurance and the waiting line was very long for the elderlies to enter the nursing homes. In these cities of Ulsan and Jeju where number of the elderly covered by long-term care insurance is relatively small, there were less facilities. 2. The nursing homes located in urban areas had higher occupancy rate and higher number of people in the waiting line. 3. The average time taken by driving from the nursing homes and health center was 10 minutes and there was not a noticeable difference between the cities. Driving from the nursing homes to hospitals in rural areas took 22 minutes which is 2.5 times of the time taken for urban areas. Daegu-si and Incheon-si had relatively short distance from the nursing homes and the hospitals while Jeju-do had the furthest. For rural areas, it is needed for health center to be equipped with a wider medical coverage, have closely connected with hospitals to minimize the differences they have from ones in rural areas. It is also needed to have ambulances equipped for tele-medical examination and treatment system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.1
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• pp.110-122
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• 1993

When voice is transmitted through packet switching network, there needs a overload control, that is, a control for the congestion which lasts short periods and occurrs in local extents. In this thesis, we analyzed the performance of the statistical packet voice multiplexer using the overload control strategy by bit dropping. We assume that the voice is coded accordng to (4,2) embedded ADPCM and that the voice packet is generated and transmitted according to the procedures in the CCITT recomendation G. 764. For the performance analysis, we must model the superposed packet arrival process to the multiplexer as exactly as possible. It is well known that interarrival times of the packets are highly correlated and for this reason MMPP is more suited for the modelling in the viewpoint of accuracy. Hence the packet arrival process in modeled as MMPP and the matrix geometric method is used for the performance analysis. Performance analysis is similar to the MMPP IG II queueing system. But the overload control makes the service time distribution G dependent on system status or queue length in the multiplexer. Through the performance analysis we derived the probability generating function for the queue length and using this we derived the mean and standard deviation of the queue length and waiting time. The numerical results are verified through the simulation and the results show that the values embedded in the departure times and that in the arbitrary times are almost the same. Results also show bit dropping reduces the mean and the variation of the queue length and those of the waiting time.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.3
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• pp.1-7
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• 2022

This paper aims to compare the mean object size of M/G/1/PS model with that of M/BP/1 model used in the web service. The mean object size is one of important measure to control and manage web service economically. M/G/1/PS model utilizes the processor sharing in which CPU rotates in round-robin order giving time quantum to multiple tasks. M/BP/1 model uses the Bounded Pareto distribution to describe the web service according to file size. We may infer that the mean waiting latencies of M/G/1/PS and M/BP/1 model are equal to the mean waiting latency of the deterministic model using the round robin scheduling with the time quantum. Based on the inference, we can find the mean object size of M/G/1/PS model and M/BP/1 model, respectively. Numerical experiments show that when the system load is smaller than the medium, the mean object sizes of the M/G/1/PS model and the M/BP/1 model become the same. In particular, when the shaping parameter is 1.5 and the lower and upper bound of the file size is small in the M/BP/1 model, the mean object sizes of M/G/1/PS model and M/BP/1 model are the same. These results confirm that it is beneficial to use a small file size in a web service.

• Journal of the Korean Mathematical Society
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• v.35 no.3
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• pp.503-525
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• 1998

In the theory of retrial queues it is usually assumed that the flow of primary customers is Poisson. This means that the number of independent sources, or potential customers, is infinite and each of them generates primary arrivals very seldom. We consider now retrial queueing systems with a homogeneous population, that is, we assume that a finite number K of identical sources generates the so called quasi-random input. We present a survey of the main results and mathematical tools for finite source retrial queues, concentrating on M/G/1//K and M/M/c//K systems with repeated attempts.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.7
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• pp.3533-3549
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• 2019

A big database utilizes the establishing network technology, and it became an emerging trend in the computing field. Therefore, there is a necessity for an optimal and effective data distribution approach to deal with this trend. This research presents the practical perspective of designing and implementing distributed database features. The proposed system has been establishing the satisfying, reliable, scalable, and standardized use of information. Furthermore, the proposed scheme reduces the vast and recurring efforts for designing an individual system for each university, as well as it is effectively participating in solving the course equivalence problem. The empirical finding in this study shows the superiority of the distributed system performance based on the average response time and the average waiting time than the centralized system. The system throughput also overcomes the centralized system because of data distribution and replication. Therefore, the analyzed data shows that the centralized system thrashes when the workload exceeds 60%, while the distributed system becomes thrashes after 81% workload.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.2
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• pp.1-10
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• 2016

In this paper, we present a new way to derive the mean cycle time of the G/G/m failure prone queue when the loading of the system approaches to zero. The loading is the relative ratio of the arrival rate to the service rate multiplied by the number of servers. The system with low loading means the busy fraction of the system is low. The queueing system with low loading can be found in the semiconductor manufacturing process. Cluster tools in semiconductor manufacturing need a setup whenever the types of two successive lots are different. To setup a cluster tool, all wafers of preceding lot should be removed. Then, the waiting time of the next lot is zero excluding the setup time. This kind of situation can be regarded as the system with low loading. By employing absorbing Markov chain model and renewal theory, we propose a new way to derive the exact mean cycle time. In addition, using the proposed method, we present the cycle times of other types of queueing systems. For a queueing model with phase type service time distribution, we can obtain a two dimensional Markov chain model, which leads us to calculate the exact cycle time. The results also can be applied to a queueing model with batch arrivals. Our results can be employed to test the accuracy of existing or newly developed approximation methods. Furthermore, we provide intuitive interpretations to the results regarding the expected waiting time. The intuitive interpretations can be used to understand logically the characteristics of systems with low loading.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.7 no.1
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• pp.15-23
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• 2003

ATM networks provide the various kinds of service which require the different Quality of Services(QoS) such as loss and delay. By statistically multiplexing of traffics and the uncertainty and fluctuation of source traffic pattern, the congestion may occur. The leaky bucket scheme is a representative policing mechanism for preventive congestion control. In this paper, we analyze the HOL(Head-of-Line) priority leaky bucket scheme. That is, traffics are classified into real-time and nonreal-time traffic. The real-time traffic has priority over nonreal-time traffic for transmission. For proposed mechanism, we obtain the system state distribution, finally the loss probability and the mean waiting time of real-time and nonreal-time traffic. The simple numerical examples also are presented.

• International Journal of Safety
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• v.8 no.2
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• pp.5-8
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• 2009

Fusing process of laser printer is the step to fuse toner on the paper and it has a great effect on fast printing speed, decrease in waiting time and improvement of printing quality. In order to improve the quality of fusing, a study on the fusion region is required. Recently, various researches are progressing in this field. In this study, the research about the temperature distribution of fusing region is performed through numerical analysis because fusing region is one of the important factors influencing fusing quality. According to results, it is ascertained that the temperature of fusing region is relative to velocity of the paper under print and has a regular distribution to width direction of the paper.

• Journal of the Korean Operations Research and Management Science Society
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• v.38 no.3
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• pp.13-22
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• 2013

Queueing system with scheduled arrivals is useful in many fields where both customers' waiting time and servers' operation time (utilization) are important, and arrival time of customers is possible to be controlled. In this paper, we analyzed the operation of ship maintenance with the queueing system with scheduled arrival. Based on the model presented by Pegden and Rosenshine [8], who dealt with exponential service time, we extended the service time distributions to phase-type distribution which is able to include a wide range of real stochastic phenomena. Since most activities in the military are carried out under tight control and schedule, scheduled arrival queue has quite good applicability in this area. In this context, we applied queue with scheduled arrival to the optimal booking time decision for the ship maintenance in the navy.

• Journal of Korea Society of Industrial Information Systems
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• v.23 no.2
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• pp.29-39
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• 2018

In this paper, we discuss a discrete-time queueing system with dyadic server control policy that combines workload control and multiple vacations. Customers arrive at the system with Bernoulli arrival process. If there is no customer to serve in the system, an idle single server spends a vacation of discrete random variable V and returns. The server repeats the vacation until the total service time of waiting customers exceeds the predetermined workload threshold D. In this paper, we derived the steady-state workload distribution of a discrete-time queueing system which is operating under a more realistic and flexible server control policy. Mean workload is also derived as a performance measure. The results are basis for the analysis of system performance measures such as queue lengths, waiting time, and sojourn time.