• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.3
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• pp.549-555
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• 2000

We propose an approximate algorithm to analyze the queuing system with n bursty and heterogeneous arrival processes. Each input process is modeled by Interrupted Bernoulli Process(IBP). We approximate N arrival processes by a single state variable and subsequently simplify the transition probability matrix of the Markov chain associated with these N arrival processes. Using this single state variable of arrival processes, we describe the state of the queuing system and analyze the system numerically with the reduced transition probability matrix. We compute the queue length distribution, the delay distribution, and the loss probability. Comparisons with simulation data show that the approximation algorithm has a good accuracy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.11B
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• pp.999-1006
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• 2003

In the paper, we investigate the impact of handoff on the packet delivery in the Mobile IPv6 networks, where the smooth handoff is adopted. That is measured by an 'unstable time period (UTP)', a 'silence time period(STP)', and a 'handoff time period (HTP)' in the mobile node's perspective. Then, we propose a queuing model to get the exact value of the handoff transient time. The numerical results show that the queuing delay for the handoff packets and the involved link (or route) capacities affect the estimated UTP, STP, and HTP. On the other hand, the damage of application caused by handoff will increases when the handoff transient time becomes longer. We show that the priority scheduling method can achieve shorter STP and UP than the FIFO scheduling method that is generally used in best-effort IP network.

• ETRI Journal
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• v.28 no.3
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• pp.301-310
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• 2006

In mobile communications, a class of variable-complexity algorithms for convolutional decoding known as sequential decoding algorithms is of interest since they have a computational time that could vary with changing channel conditions. The Fano algorithm is one well-known version of a sequential decoding algorithm. Since the decoding time of a Fano decoder follows the Pareto distribution, which is a heavy-tailed distribution parameterized by the channel signal-to-noise ratio (SNR), buffers are required to absorb the variable decoding delays of Fano decoders. Furthermore, since the decoding time drawn by a certain Pareto distribution can become unbounded, a maximum limit is often employed by a practical decoder to limit the worst-case decoding time. In this paper, we investigate the relations between buffer occupancy, decoding time, and channel conditions in a system where the Fano decoder is not allowed to run with unbounded decoding time. A timeout limit is thus imposed so that the decoding will be terminated if the decoding time reaches the limit. We use discrete-time semi-Markov models to describe such a Fano decoding system with timeout limits. Our queuing analysis provides expressions characterizing the average buffer occupancy as a function of channel conditions and timeout limits. Both numerical and simulation results are provided to validate the analytical results.

• The Journal of Information Systems
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• v.29 no.2
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• pp.131-147
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• 2020

Purpose The purpose of this study is to develop intelligent vehicle parking distribution system based on LoRa network at the circumstance of traffic congestion during cultural festival in a local city. This paper proposes a parking dispatch and distribution system using a Q-learning algorithm to rapidly disperse traffics that increases suddenly because of in-bound traffics from the outside of a city in the real-time base as well as to increase parking probability in a parking lot which is widely located in a city. Design/methodology/approach The system get information on realtime-base from the sensor network of IoT (LoRa network). It will contribute to solve the sudden increase in traffic and parking bottlenecks during local cultural festival. We applied the simulation system with Queuing model to the Yudeung Festival in Jinju, Korea. We proposed a Q-learning algorithm that could change the learning policy by setting the acceptability value of each parking lot as a threshold from the Jinju highway IC (Interchange) to the 7 parking lots. LoRa Network platform supports to browse parking resource information to each vehicle in realtime. The system updates Q-table periodically using Q-learning algorithm as soon as get information from parking lots. The Queuing Theory with Poisson arrival distribution is used to get probability distribution function. The Dijkstra algorithm is used to find the shortest distance. Findings This paper suggest a simulation test to verify the efficiency of Q-learning algorithm at the circumstance of high traffic jam in a city during local festival. As a result of the simulation, the proposed algorithm performed well even when each parking lot was somewhat saturated. When an intelligent learning system such as an O-learning algorithm is applied, it is possible to more effectively distribute the vehicle to a lot with a high parking probability when the vehicle inflow from the outside rapidly increases at a specific time, such as a local city cultural festival.

• Journal of Internet Computing and Services
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• v.23 no.5
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• pp.33-46
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• 2022

This paper, in order to minimize the ground waiting time of an Air tanker, the queuing theory, that is, a queue that calculates the waiting time under single-server and multi-server situations, was used in the study. Since the national budget and resources are limited, the unlimited increase of the logistics support service team is limited. Therefore, the number of logistic support service teams that can adaptively control the ground waiting time according to the wartime preparation stage or war environment was calculated. The results of this study provide a stipulated standard for calculating the optimal number of air tanker logistic support service teams of the Air Force, providing a basis for the logistical commander to assign logistic support service teams to each stage from peacetime to wartime.

• Journal of Korea Port Economic Association
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• v.26 no.3
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• pp.42-55
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• 2010

This paper primarily deals with a decision-making for determining the number of voyages in each ship size under a specific port structure in order to minimize the total transport cost consisting of transport cost at sea, queuing cost in port, and inventory cost in yard. As a result of computer simulation using queuing model characterized by inter-arrival time distribution, we were able to find out some combination of voyage numbers of 3 ship-size(50,000-ton, 100,000-ton, and 200,000-ton), where the total transport cost can be minimized under a specific port structure. The simulation model also allows us to figure out any trade-off relationship among sea transport cost, queuing cost in port, and inventory cost in yard. Put it differently, an attempt to reduce the sea transport cost by increasing the number of voyages of the largest ship size, the transport cost incurred in both port and yard is hypothesized to be increased and vice versa. Consequently, Port managers are required to adjust the number of annual number of voyages allocated in each ship size, put into the sea lines for importing raw materials, in order to optimize the transport costs incurred under the specific port system. We may consider a net present value(NPV) model for performing an economic feasibility analysis on port investment project. If a total discounted net benefit, including cost savings, exceeds the initial investment for an additional berth construction, then we accept the port investment project. Otherwise, we reject the proposed port investment plan.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.1087-1090
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• 2005

In all contemporary superscalar processors, the result repositories are implemented as the Reorder Buffer(ROB) slots. In such designs, the ROB is a large multi-ported structure. There are several approaches for reducing the ROB complexity in processors. The one technique relies on a distributed implementation that spreads the centralized ROB structure across the function units(FUs). Each distributed component sized to match the FU workload and with one write port and one read port on each component. We are using M/M/1 Queuing theory to determine the number of entries in each ROB component that the performance of processor depends on. Our schemes are evaluated using the simulation of CPU2000 benchmarks.

• Journal of the Korean Operations Research and Management Science Society
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• v.32 no.2
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• pp.1-15
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• 2007

This paper proposes a method for determining the number of storage rooms and designing the storage layout in warehouses for pyramid type stacks whose example are slacks for steel coils, paper rolls, and drums for oils. Formulas are derived for estimating the expected values and the variances of various handling times by cranes. From the derived formulas, the expected queuing time of road trucks is estimated. Base on the derived formulas, this study derives the cost function for determining the optimal numbers of rows, bays, and tiers of stacks and sizing cranes under the condition that the requirement for storage space is satisfied. Results of numerical analysis are provided.

• ETRI Journal
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• v.19 no.1
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• pp.13-25
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• 1997

In this paper, we propose a new queuing model, MMDP/MMDP/1/K, for an asynchronous transfer mode(ATM) multiplexer with multiple quality of service(QoS) variable bit rate (VBR) traffic in broadband-integrated services digital network (B-ISDN). We use the Markov Modulated Deterministic Process(MMDP) to approximate the actual arrival process and another MMDP for service process Using queuing analysis, we derive a formula for the cell loss probability of the ATM multiplexer in terms of the limiting probabilities of a Markov chain. The cell loss probability can be used for connection admission control in ATM multiplexer and the calculation of equivalent bandwidth for arrival traffic, The major advantages of this approach are simplicity in analysis, accuracy of analysis by comparison of simulation, and numerical stability.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.29B no.1
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• pp.11-17
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• 1992

This paper is to propose an analytical queuing model for parallel processing of sequential program with nested loops. The analytical results are compared with the results from the implemented multiprocessor system composed of four intel 8088 microprocessor, eight 2KB shared common memories, and a hardware token ring. At results, this study shows that the processed results are almost similar in proposed analytical model and real system. Proposed analytical model can be applied to evaluate parallel processing of sequential program with nested loops.