• Communications of the Korean Mathematical Society
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• v.14 no.3
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• pp.611-625
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• 1999

We consider ΜΑΡ/G/ 1 finite capacity queue with mul-tiple thresholds on buffer. The arrival of customers follows a Markov-ian arrival process(MAP). The service time of a customer depends on the queue length at service initiation of the customer. By using the embeded Markov chain method and the supplementary variable method, we obtain the queue length distribution ar departure epochs and at arbitrary epochs. This gives the loss probability and the mean waiting time by Little's law. We also give a simple numerical examples to apply the overload control in packetized networks.

• Journal of the Korea Society for Simulation
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• v.19 no.3
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• pp.109-117
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• 2010

In this study, we consider stationary waiting times in a simple fork-and-join type queue which consists of three single-server machines, Machine 1, Machine 2, and Assembly Machine. We assume that the queue has a renewal arrival process and that independent service times at each node are either deterministic or non-overlapping. We also assume that the Machines 1 and 2 have an infinite buffer capacity whereas the Assembly Machine has two finite buffers, one for each machine. Services at each machine are given by FIFO service discipline and a communication blocking policy. We derive the explicit expressions for stationary waiting times at all nodes as a function of finite buffer capacities by using (max,+)-algebra. Various characteristics of stationary waiting times such as mean, higher moments, and tail probability can be computed from these expressions.

• Journal of the Korean Society of Food Culture
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• v.26 no.4
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• pp.344-353
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• 2011

The objective of this study was to classify dining-out customers' behaviors at ski resorts based on their restaurant selection factors. Data were collected one-on-one via interview questionnaires of 178 customers at the ski resorts. The mean scores of important attributes (4.12) and satisfactory attributes (3.08) for the sport&leisure purpose group were analyzed. For the date&family trip purpose group, the important attributes (4.13) and satisfactory attributes (3.06) were evaluated, resulting in a significant difference between the two visiting-purpose groups by independent t-test (p<0.05). The recognized important attributes for the sport&leisure purpose group were food taste (4.54), hygiene (4.53), menu variety (4.22), menu price (4.15), and convenience (4.12), and the most recognizable satisfactory attributes were related to convenience (3.52), waiting time (3.95), and employee service (3.90). For the date&family trip purpose group, recognized important attributes were hygiene (4.83), food taste (4.67), menu price (4.40), convenient (4.33), menu variety (4.25), waiting time (4.21), and employee service (4.10), and marked satisfactory attributes were convenience (3.65), hygiene (3.31), atmosphere (3.25), employee service (3.23), waiting time (3.17), and food taste (3.00). These results suggest that restaurant selection attributes would be useful tools to restaurant managers in controlling the quality of foodservice and satisfying service requirements for dinning-out customers at ski resorts.

• Proceedings of the KSPS conference
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• 2005.04a
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• pp.49-52
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• 2005

Cepstral Mean Subtraction (CMS) makes effectively compensation for a channel distortion, but there are some shortcomings such as distortions of feature parameters, waiting for the whole speech sentence. By assuming that the silence parts have the channel characteristics, we consider the channel normalization using subtraction of cepstral means which are only obtained in the silence areas. If the considered techniques are successfully used for the channel compensation, the proposed method can be used for real time processing environments or time important areas. In the experiment result, however, the performance of our method is not good as CMS technique. From the analysis of the results, we found potentiality of the proposed method and will try to find the technique reducing the gap between CMS and ours method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.10
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• pp.2605-2619
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• 1996

In this paper, we evaluated performance of mobile exchange control part. Queueing network model is used for modeling of mobile exchange control part. We developed a call control processing and location registration scenartio which has a message exchange function between processors in mobile exchange control part. A network symbol are used the simulation models that are composed of the initialization module, message generation module, message routing module, message processing module, message generation module, HIPC network processing module, output analysis module. as a result of computer simulation, we obtain the processor utilization, the mean queue length, the mean waiting time of control part based on call processing and location registration capacity. The call processing and location registration capacity is referred by thenumber of call attempts in the mobile exchange and must be satisfied with the quality of service(delay time).

• Journal of Korean Institute of Industrial Engineers
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• v.16 no.2
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• pp.23-36
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• 1990

A unit-load automated guided vehicle system is considered in which a single vehicle is operated on a unidirectional path in a closed loop. The vehicle serves a manufacturing cell moving pallets from one station to another based on the "First-Encountered-First-Serve" dispatching rule. An approximation method is developed to compute the mean waiting time of an arbitrary pallet at each station. Extensive numerical experiments, performed for various problems, yield fairly good results in most of the cases compared with those obtained by simulation method.

• Journal of Korean Institute of Industrial Engineers
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• v.25 no.1
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• pp.141-149
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• 1999

In this paper, we consider multiple-class queueing systems in which the server starts a set-up as soon as the number of customers in the "start-up class" reaches threshold N. After the set-up the server starts his service. We obtain the Laplace-Stieltjes transform and the mean of the waiting times of each class of customers for FCFS and non-preemptive priority disciplines.

• Journal of radiological science and technology
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• v.35 no.1
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• pp.45-50
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• 2012

Nowadays, most of the hospital serves "one stop service" for CT scan. The patients could be taken the CT scan in the day they register for scan. On the contrary to the time convenience, patients are not satisfied with long waiting time and unkindness of staff. The objective of this study is to improve the patient's satisfaction for the CT scan, by analyzing inconvenience factors and improving the service qualities. From April 1 to August 30 in 2011, we investigated the satisfaction of patients who did examined abdomen CT scan with contrast media. We analyzed the 89 questionnaires before and after the service improvements from them. The worker's kindness, the environment of CT room and understanding about CT scan were answered by questionnaire and the waiting time of a day CT scan was drawn by medical information statistics. Also, the period before improvement was from April to June and the period after improvement was from July to September. And these questionnaire was analyzed through SPSS V. 15.0. In this study, kindness of staff, environment of CT room, intelligibility for CT scan and waiting time was explored and analyzed by SPSS V.15.0. The score of kindness was improved by 32%, satisfaction level of the environment was improved by 52.54%. The understanding level about CT scan was improved by 52.36% and the wating time of a day CT was shortened by 21% through our service enhancement programs. Consequentially, it is considered that these efforts would contribute to increase the revenue of hospital.

• 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.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.2
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• pp.234-246
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• 2007

The combination of chloral hydrate and hydroxyzine is one of the safest and most commonly used drug regimens for sedating young, uncooperative pediatric dental patients. Midazolam IM or IN and $N_2O/O_2$ inhalation is sometimes administered with chloral hydrate and hydroxyzinecombination when deeper and longer sedation is needed. The purpose of this study was to assess the outcome and safety of chloral hydrate, hydroxyzine and $N_2O/O_2$ in the sedation of a large number of uncooperative pediatric dental patients and to identify variables associated with their effectiveness. In a nine-month retrospective study, 171 records of sedation performed in 94 healthy children(male 46, female 48) with mean age of $30{\pm}8$ months were reviewed. The authors analyzed several variables such as age, sex, weight, methods of drug delivery, waiting time after drug delivery, treatment rendered, treatment time, adverse events, sedation outcome. Eighty five percent of sedation had success behavioral outcome. Sedation sessions rated success used more $N_2O/O_2$ administration and had longer treatment duration than sedation sessions rated failure. A children patient under 36 months of age had enough sleep by only oral administration and the mean waiting time of this case was significantly shorter than that of a children patient over 36 months of age. There was a clear correlation between age and $N_2O/O_2$ using tine, but no correlation between weight and $N_2O/O_2$ using time. There was no statistically significant difference among variables of treatment duration, $N_2O/O_2$ administration and adverse event.