• Proceedings of the KOR-KST Conference
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• 2002.02a
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• pp.97-139
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• 2002

The aim of the present study is to find a good quality user equilibrium assignments under time varying condition. For this purpose, this study introduces a dynamic network loading method that can maintain correct flow propagation as well as flow conservation, and it develops a novel solution algorithm that does not need evaluation of the objective function by modifying the Schittenhelm (1990)'s algorithm. This novel algorithm turns out to be efficient and convenient compared to the conventional Frank-Wolfe (1956) algorithm because the former finds solutions based on routes rather than links so that it can maintain correct flow propagation intrinsically in the time-varying network conditions. The application of dynamic user equilibrium (DUE) assignment model with this novel solution algorithm to test networks including medium-sized one shows that the present DUE assignment model gives rise to high quality discrete time solutions when we adopt the deterministic queuing model for a link performance function, and we associate flows and costs in a proper way.

• IE interfaces
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• v.16 no.spc
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• pp.76-81
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• 2003

BPMS (Business Process Management Systems) is aninformation system that systematically supports designing, administrating, and improving the business processes. It can execute the business processes by assigning tasks to human or computer agents according to the predefined definitions of the processes. In this research we developed a task assignment algorithm that can maximize overall process efficiency under the limitation of agents' capacity. Since BPMS manipulates the formal and predictable business processes, we can analyze the processes using queuing theory to achieve overall process efficiency. We first transform the business processes into queuing network model in which the agents are considered as servers. After that, workloads of agents are calculated as server utilization and we can determine the task assignment policy by balancing the workloads. This will make the workloads of all agents be minimized, and the overall process efficiency is achieved in this way. Another application of the results can be capacity planning of agents in advance and business process optimization in reengineering context. We performed the simulation analysis to validate the results and also show the effectiveness of the algorithm by comparing with well known dispatching policies.

• Asia pacific journal of information systems
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• v.26 no.3
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• pp.427-448
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• 2016

The stochastic phenomena of traffic network condition, such as traffic speed and density, are affected not only by exogenous traffic control but also by endogenous changes in service time during congestion. In this paper, we propose a mixed M/G/1 queuing model by introducing a condition-varying parameter of traffic congestion to reflect structural changes in the traffic network. We also develop congestion indices to evaluate network efficiency in terms of traffic flow and economic cost in traffic operating system using structure-changing queuing model, and perform scenario analysis according to various traffic network improvement policies. Empirical analysis using Korean highway traffic operating system shows that our suggested model better captures structural changes in the traffic queue. The scenario analysis also shows that occasional reversible lane operation during peak times can be more efficient and feasible than regular lane extension in Korea.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.10
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• pp.684-690
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• 2014

In this work we investigate the benefit of multicast in the delivery of video data over the mobile MBMS network. In order to quantify the benefit in a practical aspect, this work proposes an analytic framework that employs a combined statistical and queuing model, where a queuing model represents the behavior of user's access to the video service and the statistical model captures the popularity of the video contents, via which we draw out a more realistic intuition for the expected benefit from multicast. Finally, we present results of numerical experiment that illustrates the validity of the proposed work.

• ETRI Journal
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• v.25 no.1
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• pp.34-40
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• 2003

This paper considers a TMN-based management system for the management of public ATM switching networks using a four-level hierarchical structure consisting of one network management system, several element management systems, and several agent-ATM switch pairs. Using Jackson's queuing model, we analyze the effects of one TMN command on the performance of the component ATM switch in processing local calls. The TMN command considered is the permanent virtual call connection. We analyze four performance measures of ATM switches- utilization, mean queue length and mean waiting time for the processor directly interfacing with the subscriber lines and trunks, and the call setup delay of the ATM switch- and compare the results with those from Jackson's queuing model.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.07a
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• pp.395-396
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• 2014

최근 급증하는 교통 혼잡으로 인해 시간적/물리적 손실이 크게 발생하고 있다. 이러한 교통난 해소는 시설투자만으로는 근본적인 해결책이 될 수 없다는 판단 하에 지난 수년간 보다 정확한 교통량을 예측하기 위해 다양한 교통량 예측 모델들이 개발되어왔다. 그러나 기존 모델들은 회기분석을 통해 과거 교통량을 분석하고 과거의 교통패턴이 미래에 지속적으로 연장된다는 가정 하에 연구되었기 때문에 실시간으로 급변하는 불규칙한 교통 패턴에 대한 예측의 신뢰성을 떨어트린다. 이를 위해 본 논문에서는 큐잉 네트워크 모델 기반의 교통량 예측 모델을 설계 하고 이를 바탕으로 안드로이드 기반의 애플리케이션을 구현하였다.

• Journal of Communications and Networks
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• v.15 no.2
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• pp.222-227
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• 2013

This paper presents an analytical framework for dynamic spectrum allocation in cognitive radio networks. We propose a distributed queuing based Markovian model each for single channel and multiple channels access for a contending user. Knowledge about spectrum mobility is one of the most challenging problems in both these setups. To solve this, we consider probabilistic channel availability in case of licensed channel detection for single channel allocation, while variable data rates are considered using channel aggregation technique in the multiple channel access model. These models are designed for a centralized architecture to enable dynamic spectrum allocation and are compared on the basis of access latency and service duration.

• ETRI Journal
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• v.19 no.4
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• pp.344-362
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• 1997

The delay which is one of the quality of service parameters is considered to be a crucial factor for the effective usage of real-time audio and video streams in interactive multimedia collaborations. Among the various causes of the delay, we focus in this paper on the local delay concerned with the schemes which handle continuous inflow of encoded data from constant or variable bit-rate audio and video encoders. We introduce two kinds of implementation approaches, pull model and push model. While the pull model periodically pumps out the incoming data from the system buffer, the push model receives events from the device drivers. From our experiments based on Windows NT 3.51, it is shown that the push model outperforms the other for both constant and variable bit-rate streams in terms of the local delay, when the system suffers reasonable loads. We interpret this experimental data with M/G/1 multiple vacation queuing theories, and show that it is consistent with the queuing theoretic interpretations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.1
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• pp.107-114
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• 2011

Today the company adopts to use information management method at the network base such as internet, intranet and so on for the speed of business. Therefore the security of information asset protection and continuity of business within company in relation to this is directly connected to the credibility of the company. This paper secures continuity to the certified users using queuing model for the business interruption issue caused by DDoS attack which is faced seriously today. To do this I have reflected overloaded traffic improvement process to the queuing model through the analysis of related traffic information and packet when there occurs DDoS attack with worm/virus. And through experiment I compared and analyzed traffic loading improvement for general network equipment.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.7
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• pp.2257-2285
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• 2022

Cyber-physical systems (CPS) have been growing exponentially due to improved cloud-datacenter infrastructure-as-a-service (CDIaaS). Incremental expandability (scalability), Quality of Service (QoS) performance, and reliability are currently the automation focus on healthy Tier 4 CDIaaS. However, stable QoS is yet to be fully addressed in Cyber-physical data centers (CP-DCS). Also, balanced agility and flexibility for the application workloads need urgent attention. There is a need for a resilient and fault-tolerance scheme in terms of CPS routing service including Pod cluster reliability analytics that meets QoS requirements. Motivated by these concerns, our contributions are fourfold. First, a Distributed Non-Recursive Cloud Model (DNRCM) is proposed to support cyber-physical workloads for remote lab activities. Second, an efficient QoS stability model with Routh-Hurwitz criteria is established. Third, an evaluation of the CDIaaS DCN topology is validated for handling large-scale, traffic workloads. Network Function Virtualization (NFV) with Floodlight SDN controllers was adopted for the implementation of DNRCM with embedded rule-base in Open vSwitch engines. Fourth, QoS evaluation is carried out experimentally. Considering the non-recursive queuing delays with SDN isolation (logical), a lower queuing delay (19.65%) is observed. Without logical isolation, the average queuing delay is 80.34%. Without logical resource isolation, the fault tolerance yields 33.55%, while with logical isolation, it yields 66.44%. In terms of throughput, DNRCM, recursive BCube, and DCell offered 38.30%, 36.37%, and 25.53% respectively. Similarly, the DNRCM had an improved incremental scalability profile of 40.00%, while BCube and Recursive DCell had 33.33%, and 26.67% respectively. In terms of service availability, the DNRCM offered 52.10% compared with recursive BCube and DCell which yielded 34.72% and 13.18% respectively. The average delays obtained for DNRCM, recursive BCube, and DCell are 32.81%, 33.44%, and 33.75% respectively. Finally, workload utilization for DNRCM, recursive BCube, and DCell yielded 50.28%, 27.93%, and 21.79% respectively.