• Journal of Korean Institute of Industrial Engineers
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• v.22 no.3
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• pp.377-385
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• 1996

We present an approximate algorithmic approach for the m-server fork-join queueing system with infinite queue capacity. We analyze the system size and queue waiting time. We assume Poisson arrival process and independent exponential service times.

• Journal of the Korea Safety Management & Science
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• v.11 no.4
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• pp.213-220
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• 2009

The minimum latency problem, also known as the traveling repairman problem and the deliveryman problem is to minimize the overall waiting times of customers, not to minimize their routing times. In this research, a genetic algorithm, a clonal selection algorithm and a population management genetic algorithm are introduced. The computational experiment shows the objective value of the clonal selection algorithm is the best among the three algorithms and the calculating time of the population management genetic algorithm is the best among the three algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.3
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• pp.277-287
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• 1992

In this paper, we study the performance eualuations of the FDDI Network, by mathmeticlal analysis and simulation, in which the Integrated Voice/Data transmission system with voice traffic in synchronous mode and data traffic inasynchronous mode.For the mean waiting times of Voice/Data packet, we use two-state of Marcov models for voice traffic with talkspurt and silenci state, and the data traffic would traffic would transmit at the silence state of voice traffic. By the mean wating times, we analyze the relations between synchronous and asynchronous mode. As a result, using Sync/Async mode with voice and data, voice was not under influnece of data traffic. and in the same time,data can be tanaxmitted in a short waiting time, too.

• Journal of the Korea Society for Simulation
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• v.21 no.4
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• pp.11-24
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• 2012

We compared a DBR(drum-buffer-rope) system with a CONWIP(constant work-in-process) system in a production line with constant processing times. Based on the observation that a WIP-controlled line production system such as DBR and CONWIP is equivalent to a m-node tandem queue with finite buffer, we applied a max-plus algebra based solution method for the tandem queue to evaluate the performance of two systems. Numerical examples with 6 workstations were also used to demonstrate the proposed analysis. The mathematical analyses support that CONWIP outperforms DBR in terms of expected waiting time and WIP. Unlike the CONWIP case, sequencing workstations in a DBR affects the performance of the system. Delaying a bottleneck station in a DBR reduces expected waiting time.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.77-85
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• 2015

This paper presents our performance evaluation after the way of minimizing waiting times between channel switching for eMBMS(evolved Multimedia Broadcast/Multicast Services) technique in LTE-Advanced systems. Existing composition of MBMS using IGMP(Internet Group Management Protocol) transfers the data with Multicast from BM-SC(Broadcast Multicast Service Center) to eNB(evolevd Node B) and with Broadcast from eNB to UE(User Equipment). Therefore, in case of channel switching, IGMP Join report should be transferred to BM-SC and then wait user's contents to be retransferred from eNB. To achieve this, Subscriber Channel technique of priorities is used for minimizing waiting times between channel switching as UE broadcasts favorite channels in advance.

• Advances in aircraft and spacecraft science
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• v.9 no.4
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• pp.335-347
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• 2022

Airport operations are well-known as a bottleneck in the air traffic system, putting growing pressure on the world's busiest airports to schedule arrivals and departures as efficiently as possible. Effective planning and control are essential for increasing airport efficiency and reducing aircraft delays. Many algorithms for controlling the arrival/departure queuing area are handled, considering it as first in first out queues, where any available aircraft can take off regardless of its relative sequence with other aircraft. In the suggested system, this problem was compared to the problem of scheduling n tasks (plane takeoffs and landings) on a multiple machine (runways). The proposed technique decreases delays (via efficient runway allocation or allowing aircraft to be expedited to reach a scheduled time) to enhance runway capacity and decrease delays. The aircraft scheduling problem entails arranging aircraft on available runways and scheduling their landings and departures while considering any operational constraints. The topic of this work is the scheduling of aircraft landings and takeoffs on multiple runways. Each aircraft's takeoff and landing schedules have time windows, as well as minimum separation intervals between landings and takeoffs. We present and evaluate a variety of comprehensive concepts and solutions for scheduling aircraft arrival and departure times, intending to reduce delays relative to scheduled times. When compared to First Come First Serve scheduling algorithm, the suggested strategy is usually successful in reducing the average waiting time and average tardiness while optimizing runway use.

• Health Policy and Management
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• v.19 no.3
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• pp.27-44
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• 2009

The length of stay in emergency departments has been used as a quality indicator to reflect the overall efficiency of emergency care. Identifying characteristics associated with length of stay is critical to monitor overcrowding and improve efficient throughput function of emergency departments. This study examined the level of waiting time for initial assessment by physician and length of stay in emergency departments. Furthermore, we investigated the characteristics of patients' attendance associated with length of stay. An observational study was performed for a sample of 1,526 patients visiting ten nation-wide emergency departments. A structured form was designed to collect information about patients' demographics, route of admission, time and mode of arrival, triage level, cause of attendance, initial assessment time by physician, departure time, and disposition. Multiple regression analysis was performed to determine factors associated with length of stay. The average length of stay was 209.4 minutes (95% confidence interval [CI]=197.1-221.7), with a mean waiting time for initial assessment of 5.9 minutes (95% CI=5.1-6.7). After controlling for emergency department characteristics, increasing age, longer waiting times, attendance due to diseases, higher acuity, multiple diagnoses($\geq$2) and requiring admission or transfer to other health care facilities were positively associated with length of stay in emergency departments. The findings suggest that both patients' characteristics and the flow between emergency departments and parent hospitals should be taken into account in predicting length of stay in emergency departments.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.2829-2834
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• 2013

The objective was to analyze the radiotherapy (RT) practice at the cancer centre of a tertiary academic medical institution in Delhi. This audit from an Indian public institution covered patient care processes related to cancer diagnosis, integration of RT with other anti-cancer modalities, waiting time, overall treatment time, and compliance with RT. Over a period of one year, all consecutively registered patients in radiotherapy were analyzed for the audit cycle. Analysis of 1,030 patients showed median age of 49.6 years, with presentation as stage I and II in 14.2%, stage III and IV in 71.2% and unknown stage in 14.6%. A total of 974 (95%) were advised for RT appointment; 669 (68.6%) for curative intent and 31.4% for palliation. Mean times for diagnostic workup and from registration at cancer centre to radiotherapy referral were 33 and 31 days respectively. Median waiting time to start of RT course was 41 days. Overall RT compliance was 75% and overall duration for a curative RT course ranged from 50 days to 61 days. Non-completion and interruption of RT course were observed in 12% and 13% respectively. Radiotherapy machine burden in a public cancer hospital in India increases the waiting time and 25% of advised patients do not comply with the prescribed treatment. Infrastructure, machine and manpower constraints lead to more patients being treated on cobalt (74%) and by two-dimensional (78%) techniques.

• Communications for Statistical Applications and Methods
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• v.24 no.3
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• pp.193-209
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• 2017

The power Lindley distribution with some of its properties is considered in this article. Maximum likelihood, least squares, maximum product spacings, and Bayes estimators are proposed to estimate all the unknown parameters of the power Lindley distribution. Lindley's approximation and Markov chain Monte Carlo techniques are utilized for Bayesian calculations since posterior distribution cannot be reduced to standard distribution. The performances of the proposed estimators are compared based on simulated samples. The waiting times of research articles to be accepted in statistical journals are fitted to the power Lindley distribution with other competing distributions. Chi-square statistic, Kolmogorov-Smirnov statistic, Akaike information criterion and Bayesian information criterion are used to access goodness-of-fit. It was found that the power Lindley distribution gives a better fit for the data than other distributions.

• IE interfaces
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• v.24 no.4
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• pp.274-280
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• 2011

Delayed access to surgery may lead to deterioration in the patient condition, poor clinical outcomes, increase in the probability of emergency admission, or even death. The purpose of this work is to decide the number of patients selected from a waiting list and to schedule them in accordance with the operating room capacity in the next period. We formulate the problem as an infinite horizon Markov Decision Process (MDP), which attempts to strike a balance between the patient waiting times and overtime works. Structural properties of the proposed model are investigated to facilitate the solution procedure. The proposed procedure modifies the conventional value iteration method along with the binary search technique. An example of the optimal policy is provided, and computational results are given to show that the proposed procedure improves computational efficiency.