• The Journal of the Korea Contents Association
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• v.8 no.9
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• pp.34-41
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• 2008

Existing mobility support scheme like MIPv4 has the delay at data transfer and Triangle routing problem. This paper proposes the new mobility support scheme and method that can overcome the problem using MPLS LSP in Next Generation Network. The proposed scheme overcomes the problem by introducing the LMS(Location Management Server) managing the location of the mobile terminal and the MPLS LSP between FA for a tunneling. We shows on the mathematical analysis using the queuing theory that this proposed scheme is more superior to the existing method(MIP).

• Industrial Engineering and Management Systems
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• v.15 no.1
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• pp.19-31
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• 2016

A design method of the network for automated transporters mounted on rails is addressed for automated container terminals. In the network design, the flow directions of some path segments as well as routes of transporters for each flow requirement must be determined, while the total transportation and waiting times are minimized. This study considers, for the design of the network, the waiting times of the transporters during the travel on path segments, intersections, transfer points below the quay crane (QC), and transfer points at the storage yard. An algorithm, which is the combination of a modified Dijkstra's algorithm for finding the shortest time path and a queuing theory for calculating the waiting times during the travel, is proposed. The proposed algorithm can solve the problem in a short time, which can be used in practice. Numerical experiments showed that the proposed algorithm gives solutions better than several simple rules. It was also shown that the proposed algorithm provides satisfactory solutions in a reasonable time with only average 7.22% gap in its travel time from those by a genetic algorithm which needs too long computational time. The performance of the algorithm is tested and analyzed for various parameters.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.10
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• pp.4724-4747
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• 2016

To efficiently reduce on-grid energy consumption, the admission control algorithm in the hybrid energy powered cellular network (HybE-Net) with base stations (BSs) powered by on-grid energy and solar energy is studied. In HybE-Net, the fluctuation of solar energy harvesting and energy consumption may result in the imbalance of solar energy utilization among BSs, i.e., some BSs may be surplus in solar energy, while others may maintain operation with on-grid energy supply. Obviously, it makes solar energy not completely useable, and on-grid energy cannot be reduced at capacity. Thus, how to control user admission to improve solar energy utilization and to reduce on-grid energy consumption is a great challenge. Motivated by this, we first model the energy flow behavior by using stochastic queue model, and dynamic energy characteristics are analyzed mathematically. Then, fuzzy logic based admission control algorithm is proposed, which comprehensively considers admission judgment parameters, e.g., transmission rate, bandwidth, energy state of BSs. Moreover, the index of solar energy utilization balancing is proposed to improve the balance of energy utilization among different BSs in the proposed algorithm. Finally, simulation results demonstrate that the proposed algorithm performs excellently in improving solar energy utilization and reducing on-grid energy consumption of the HybE-Net.

• Journal of Korean Society of Transportation
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• v.22 no.4 s.75
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• pp.19-30
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• 2004

Due to the inefficient operation of the existing logistic facilities, the complicated distribution structure, and closed utilization of logistic information are causing high logistic costs. The general improvement in the distribution structure and the expansion of the logistic facilities are needed for solving these problems. However, existing unit-scale forecast is not considering the loading and unloading characteristics of the trucks and the improvement of operation efficiency from the mechanization and automation of the loading and unloading works. The queuing theory based on the status quo of the cargo trucks to the cargo terminals is considered in this study. The optimal scale estimation method(OSCM) which the loading and unloading characteristics of the cargo trucks were taken into consideration was suggested. Also, the relationship between the optimal scale of the cargo terminal and the mechanization, automation, and informationization of the present loading and unloading system was investigated. As a result, it showed that the regularity of the truck arrival and service times had less influence on the scale of the cargo terminal, but the improvement of the loading and unloading speeds and the service rate of the trucks did more influence on it.

• Journal of Korean Society of Transportation
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• v.28 no.1
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• pp.143-156
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• 2010

The walking is very important because of its environment friendly and low accident rate, and transferring is also important as increasing public transportation uses. Facilities for transferring such as transfer path in Sadang station and internal stairways in Sindorim station are the object of this paper. Using preexistence methodology for Level of Service is not appropriate to transferring facilities because they are occurred only when the train arrive that station. To solve this problem, this paper uses queuing theory and utilization factor. In result, we can get Level of Service which can simulate real situation of the facilities by using new methodology which introduce by this paper. Also it reveals that preexistence methodology cannot simulate real phenomenon in transferring center.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.6
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• pp.337-343
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• 2006

The Stack Resource Policy (SRP) is a real-time synchronization protocol with some distinct properties. One of such properties is early blocking; the execution of a job is delayed instead of being blocked when requesting shared resources. If SRP is used with dynamic priority scheduling such as Earliest Deadline First (EDF), the early blocking requires that a scheduler should select the highest-priority job among the jobs that will not be blocked, incurring runtime overhead. In this paper, we analyze the runtime overhead of EDF scheduling when SRP is used. We find out that the overhead of job search using the conventional implementations of ready queue and job search algorithms becomes serious as the number of jobs increases. To solve this problem, we propose an alternative data structure for the ready queue and an efficient job-search algorithm with O([log$_2n$]) time complexity.

• Journal of the Korean Operations Research and Management Science Society
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• v.37 no.4
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• pp.73-93
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• 2012

In recent years, service delivery systems employing a self-service approach have been rapidly spreading. Since a self-service system provides a lower product price, it attracts more customers. However, some system managers are still hesitant to accept a self-service system, because there is no systematic model to predict its performance. Therefore, this research attempts to provide a systematic and quantitative model to predict the performance of a self-service system, focused specifically on a self-service gas station. Under this model, the traditional queuing theory was adopted to describe the general self-service process, but it is also assumed that some changes occur in both the customer arrival rate and the service performance rate. In particular, the price elasticity was introduced to capture the change in the customer arrival rate, and the existence of learning effect and helpers were assumed to design the changed service performance rate. Under these assumptions, a simulation model for a self-service gas station is established, and three performance measurements, such as average number of customers, average waiting time, and Utilization are observed, depending on the changes in price difference and helper-operating time. In this research, the optimal operation strategy for price differentiation and helper-operating time is proposed in accordance with the level of the customer learning rate. Although this research confines the scope of the study to the self-service gas station model, the results of this research can be applied to any type of self-service system.

• Journal of the Korean Society for Railway
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• v.13 no.3
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• pp.339-348
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• 2010

The government continues to make efforts to improve effectiveness, integration and connectivity of public transportation systems. But there have been only a few studies about it. This paper addresses the quality evaluation of pedestrian facility service in transfer stations at urban railroad. LOS (Level Of Service) model of urban railroad by facility based on the body ellipse and density recalculated considering the recent Korean body standard and the suggested Pedestrian Moving Equivalent (PME) and Pedestrian Waiting Equivalent (PWE). For LOS model for the ticket booths and ticket vending machines, queuing theory has been applied to determine LOS of Pedestrians. And the importance weights among the pedestrian facilities is obtained by applying AHP analysis. Lastly, this paper shows and discusses the evaluation results of overall LOS of pedestrian facilities of five urban railroad transfer stations in Seoul.

• Industrial Engineering and Management Systems
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• v.9 no.3
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• pp.285-293
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• 2010

To obtain visible and traceable information from the supply chain, HW/SW standards for the EPC global network, which process electronic product code (EPC) data read from Radio frequency identification (RFID) tags, are regarded as the de facto industry standard. Supply chain participants install information service systems and provide logistics information to partners by following the EPCglobal architecture framework. Although quality of service (QoS) is essential for providing dependable and scalable services as pointed out by Auto-ID Lab, only a few models for the performance analysis of QoS-related work have been developed in the context of EPC information service systems. Specifically, doing so allows alternative design choices to be tested in an easy and cost-effective manner and can highlight potential performance problems in designs long before any construction costs are incurred. Thus, in this study we construct a model of an EPC information service system for the purposes of performance analysis and designing a dependable system. We also develop a set of building blocks for analytical performance models. To illustrate how the model works, we determine the characteristics of an EPC information service system and then select a combination of these proven modeling concepts. We construct a performance model that considers the response time and shows how to derive meaningful performance values. Finally, we compare the analytical results to measurements of the EPC information service system.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.7
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• pp.847-862
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• 1999

본 논문에서는 유한버퍼의(finite-buffered) 동기화된(synchronous) 큐잉모델(queueing model)을 이용하여 명령어들간의 병렬성, 분기명령의 빈도수, 분기예측(branch prediction)의 정확도, 캐쉬미스 등의 파라미터들을 고려하여 프로세서의 명령어 실행율을 예측하며 캐쉬의 성능과 파이프라인 성능간의 관계를 분석할 수 있는 새로운 해석적 모델을 제안하였다. 해석적 모델은 모델의 타당성을 검증하기 위해서 시뮬레이션을 수행하여 얻은 결과와 비교하였다. 해석적 모델과 시뮬레이션을 비교한 결과 대부분 10% 오차 내에서 일치하였다. 본 연구를 통하여 얻은 해석적 모델을 사용하면 시뮬레이션에서는 드러나지 않는 성능제약의 원인에 대한 명확한 규명이 가능하기 때문에 성능향상을 위한 설계자료를 얻을 수 있으며, 시스템 성능 밸런스를 위한 캐쉬와 비순차이슈 파이프라인 성능간의 관계에 대한 정확한 분석이 가능하다.Abstract This research presents a novel analytic model to predict the instruction execution rate of superscalar processors using the queuing model with finite-buffer size and synchronous operation mode. The proposed model is also able to analyze the performance relationship between cache and pipeline. The proposed model takes into account various kinds of architectural parameters such as instruction-level parallelism, branch probability, the accuracy of branch prediction, cache miss, and etc.. To prove the correctness of the model, we performed extensive simulations and compared the results with the analytic model. Simulation results showed that the proposed model can estimate the average execution rate accurately within 10% error compared to simulation results. The proposed model can explain the causes of performance bottleneck which cannot be uncovered by the simulation method only. The model is also able to show the effect of the cache miss on the performance of out-of-order issue superscalar processors, which can provide an valuable information in designing a balanced system.