• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.10
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• pp.24-34
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• 2003

In this paper, we investigated the problems of the offset time based service differentiation scheme for optical burst switching (OBS) networks, and proposed the preemption-based service differentiation scheme which combines a preemption channel selection algorithm and channel partitioning algorithm. The proposed preemption channel selection algorithm minimizes the length of preempted bursts to improve the channel efficiency, while the proposed channel partitioning algorithm controls the degree of service differentiation between service classes. The simulation results showed that the proposed schemes could improve the end-to-end performance and effectively provide controllable service differentiation in the multiple hop network environments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.9
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• pp.1906-1914
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• 2012

In this paper, relative service differentiation in JET based optical burst-switched networks with deflection routing is presented. It differs from conventional schemes in that it tries to make the loss rate of high class bursts as low as possible while maintaining the desired proportional ratio between the high class bursts and low class bursts. Strategies applied to it are dynamic wavelength allocation and the preemption which are combined to deflection routing. With dynamic wavelength allocation, the number of wavelengths allocated to high class bursts are dynamically changed. Preemption which gives more preference to high class bursts is also applied to decrease its loss rate. To lower the loss rate, deflection routing is applied for any kind of traffic. With those strategies, the suggested scheme shows desired properties that the loss rate of high class traffic is as lowered as possible. A queueing model for the scheme is developed to approximate loss ratio and the numerical results show that the proposed scheme provisions relative service differentiation.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.4
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• pp.345-353
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• 2010

A general solution in global self-position location of robot is to generate multiple hypothesis in self-position of robot, which is to look for the most positive self-position by evaluating each hypothesis based on features of observed landmark. Markov Localization(ML) or Monte Carlo Localization(MCL) to be the existing typical method is to evaluate all pairs of landmark features and generated hypotheses, it can be said to be an optimal method in sufficiently calculating resources. But calculating quantities was proportional to the number of pairs to evaluate in general, so calculating quantities was piled up in wide environments in the presence of multiple pairs if using these methods. First of all, the positive and promising pairs is located and evaluated to solve this problem in this paper, and the newly locating method to make effective use of calculating time is proposed. As the basic method, it is used both RANSAC(RANdom SAmple Consensus) algorithm and preemption scheme to be efficiency method of RANSAC algorithm. The calculating quantity on each observation of robot can be suppressed below a certain values in the proposed method, and the high location performance can be determined by an experimental on verification.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.171-180
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• 2004

CDP(handoff Call Dropping Probability) and CBP(new Call Blocking Probability) have been used as two important call level QoS parameters in cellular mobile communications. But, many methods to reduce CDP without considering CBP have been studied, and hand-off call priority scheme has been introduced. But the use of hand-off call priority scheme increases CBP and decreases channel utilization rate depending on the number of reserved channel for priority. In this paper, we propose a CAC(Call Admission Control) algorithm with overflow and preemption to solve the problem caused by considering CDP and CBP in calculation of the number of channel reserved. The problem is the increase of CDP as the traffic load increases. In our CAC algorithm, hand-off call is permitted to use(overflow) unreserved and unused channel if there is no reserved and unused channel, and new call is permitted to use(preemption) the channel overflowed by hand-off call if there is no unreserved and unused channel. This mechanism of calculation of the number of reserved channel and CAC algorithm is expected to increase channel utilization rate, and can be applied to media-based QoS provision in cellular mobile communications.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.12
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• pp.2835-2842
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• 2013

In this paper, service differentiation scheme using optical buffer that is reduced in size with slow-light technology in optical burst switching networks is presented. In suggested scheme, each outport has buffer to store high-class burst only in case that all its wavelengths are occupied. When all wavelengths are being used, a new arriving high-class burst goes into the buffer and waits until a burst is serviced. As soon as a burst is serviced with a wavelength, the high-class burst at buffer is allocated to the free wavelength. In case that low-class burst is arriving under the same situation, it is not stored at the buffer but discarded. An analytical model is derived to analyze the performance of the suggested scheme and compare its performance with the conventional scheme such as preemption and deflection as well as no service differentiations.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.137-154
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• 2019

This study analysed the center control emergency vehicle preemption[EVP] test result on the 1.782 km section around Gangbuk Fire Station. The pros and cons between center control and site control EVP was compared through the review of existing research. The test site was selected based on the higher link speed for choosing low congested area and 4 to 6 lane road. EVP operates green extension under the estimated arrival time to each intersection. This study is about EVP system field application and its evaluation by analyzing EVP operation result with the emergency vehicle's trace, GPS data. The impact on the surrounding traffic was analysed in delay from the queue length survey. Analysis showed the decrease in averge travel time 41.81%, but the increase in delay of surrounding traffic slightly. It is expected that EVP can be applied to the expanded area by researching EVP compensation scheme.

• Journal of Korean Institute of Industrial Engineers
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• v.25 no.1
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• pp.47-55
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• 1999

This paper develops an efficient heuristic algorithm for scheduling workforce level that can accommodate all the requested maintenance jobs. Each job has its own release and due dates as well as man-day requirement, and must be scheduled in a non-interrupted time interval, namely, without preemption. Duration of each job is not fixed, but to be determined within given specific range. The objective is to minimize workforce level to complete all the requested maintenance jobs. We show that the problem can be seen as a variant of the two-dimensional bin-packing problem with some additional constraints. A non-linear mixed integer programming model for the problem is developed, and an efficient heuristic algorithm based on bin-packing algorithms is proposed. In order to evaluate goodness of the solution obtained from the proposed algorithm, a scheme for getting a good lower bound for the optimum solution is presented and analyzed. The computational experiment shows that the proposed algorithm performs quite satisfactorily.

• ETRI Journal
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• v.29 no.3
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• pp.259-269
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• 2007

The ubiquitous flexible operating system (UbiFOS) is a real-time operating system designed for cost-conscious, low-power, small to medium-sized embedded systems such as cellular phones, MP3 players, and wearable computers. It offers efficient real-time operating system services like multi-task scheduling, memory management, inter-task communication and synchronization, and timers while keeping the kernel size to just a few to tens of kilobytes. For flexibility, UbiFOS uses various task scheduling policies such as cyclic time-slice (round-robin), priority-based preemption with round-robin, priority-based preemptive, and bitmap. When there are less than 64 tasks, bitmap scheduling is the best policy. The scheduling overhead is under 9 ${\mu}s$ on the ARM926EJ processor. UbiFOS also provides the flexibility for user to select from several inter-task communication techniques according to their applications. We ported UbiFOS on the ARM9-based DVD player (20 kB), the Calm16-based MP3 player (under 7 kB), and the ATmega128-based ubiquitous sensor node (under 6 kB). Also, we adopted the dynamic power management (DPM) scheme. Comparative experimental results show that UbiFOS could save energy up to 30% using DPM.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12B
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• pp.811-817
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• 2005

Efficient bandwidth management is necessary in order to provide high quality service to users in a multimedia wireless/mobile network. In this paper, I propose an on-line load balancing algorithm with preemption. This technique is able to balance the traffic load among cells accommodating heterogeneous multimedia services while ensuring efficient bandwidth utilization. The most important features of my algorithm are its adaptability, flexibility and responsiveness to current network conditions. In addition, my online scheme to control bandwidth adaptively is a cell-oriented approach. This approach has low complexity making it practical for real cellular networks. Simulation results indicate the superior performance of my algorithm.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.3
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• pp.66-75
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• 2017

Priority disciplines are an important scheme for service systems to differentiate their services for different classes of customers. (N, n)-preemptive priority disciplines enable system engineers to fine-tune the performances of different classes of customers arriving to the system. Due to this virtue of controllability, (N, n)-preemptive priority queueing models can be applied to various types of systems in which the service performances of different classes of customers need to be adjusted for a complex objective. In this paper, we extend the existing (N, n)-preemptive resume and (N, n)-preemptive repeat-identical priority queueing models to the (N, n)-preemptive repeat-different priority queueing model. We derive the queue-length distributions in the M/G/1 queueing model with two classes of customers, under the (N, n)-preemptive repeat-different priority discipline. In order to derive the queue-length distributions, we employ an analysis of the effective service time of a low-priority customer, a delay cycle analysis, and a joint transformation method. We then derive the first and second moments of the queue lengths of high- and low-priority customers. We also present a numerical example for the first and second moments of the queue length of high- and low-priority customers. Through doing this, we show that, under the (N, n)-preemptive repeat-different priority discipline, the first and second moments of customers with high priority are bounded by some upper bounds, regardless of the service characteristics of customers with low priority. This property may help system engineers design such service systems that guarantee the mean and variance of delay for primary users under a certain bounds, when preempted services have to be restarted with another service time resampled from the same service time distribution.