• Journal of the Korean Operations Research and Management Science Society
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• v.20 no.1
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• pp.35-54
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• 1995

Routing in ATM network is set up by combination of both virtual path routing and virtual channel routing. While virtual channel is similar concept to virtual circuit of data networks, virtual path is a special concept which is not used in traditional data networks. Virtual path can rearrange in structure and size by simply changing virtual path routing tables and giving the network the capability to eash allocate network resources according to the demand needs. This paper provides reconfiguration models of virtual path network which give the bandwidth of link and the routing path for each traffic class. The reconfiguration models are network optimization problems of multicommodity network flow type. The numerical examples are also included.

• Journal of the Korean Operations Research and Management Science Society
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• v.21 no.1
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• pp.1-17
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• 1996

There have been considerable researches for solving large-scale separable convex optimization ptoblems. In this paper we present a method for large-scale nonseparable smooth convex optimization problems with block-angular linear constraints. One of them is occurred in reconfiguration of the virtual path network which finds the routing path and assigns the bandwidth of the path for each traffic class in ATM (Asynchronous Transfer Mode) network [1]. The solution is approximated by solving a sequence of the block-angular structured separable quadratic programming problems. Bundle-based decomposition method [10, 11, 12]is applied to each large-scale separable quadratic programming problem. We implement the method and present some computational experiences.

• Korean Management Science Review
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• v.25 no.2
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• pp.25-42
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• 2008

CDMA/TOD with asymmetric capacity allocation between uplink and downlink is a highly attractive solution to support the next generation mobile systems. This is because flexible asymmetric allocation of capacity to uplink and downlink usually improves the utilization of the limited bandwidth. In this paper, we mathematically formulate an optimal timeslot and code allocation problem, which is to maximize the total utility considering the numbers of codes(channels) allocated to each data class and the forced terminations of previously allocated codes. We also suggest a real-time integrated timeslot and code allocation scheme using Lagrangean relaxation and subgradient optimization techniques. Experimental results show that the proposed scheme provides high-quality solutions in a fast time.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.892-895
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• 2002

We propose new buffer management scheme for GFR service through FIFO queuing discipline. Proposed scheme can provide minimum bandwidth guarantees for GFR VCs as well as improve the fairness among the competing GFR VCs on a single FIFO queue. From simulation results, we demonstrate the proposed scheme fulfills the requirements of GFR service as well as improves the TCP throughput.

• Journal of Korea Society of Digital Industry and Information Management
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• v.7 no.2
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• pp.47-58
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• 2011

Snoop was suitably designed for wired and wireless network as having snoop agent module in BS(Base Station) which is connecting to both wired and wireless network in order to supplement the problems of TCP. This study examined performance difference by using the web traffic taken wide possession in current internet traffic. The web traffic has greater amount of traffic, shorter life time, and smaller size than other traffics. This study found that snoop producing performance improvement of wireless network in the network mixed with the wired and wireless lead performance loss when transmitting web traffic. This study found that in case of web traffic is transmitted it bring a performance improvement of web traffic as computing BWE((Bandwidth Expansion), and also found that this study prove of performance improvement by decreasing local retranmission.

• Journal of Communications and Networks
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• v.4 no.2
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• pp.136-147
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• 2002

In this paper, the maximal capacity of the data network link has attempted to be exploited by using the dynamic allocation strategy. We propose a new methodology based on the economic models for competing traffic classes (classes of sessions) in packet networks. As the demand for network services accelerates, users' satisfaction to the service level might decrease due to the congestion at the network nodes. To prevent this, efficient allocation of a networks resources, such as available bandwidth and switch capacity, is needed. By using the so-called user profile as well as the utility (e.g., data rate) functions, it is possible to allocate data rates and other utilities using the arbitrary number of QoS classes, say $0.01,...,$10.

• Journal of Communications and Networks
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• v.14 no.6
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• pp.692-702
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• 2012

Supporting quality of service (QoS) guarantees for diverse multimedia services are the primary concerns for WiMAX (IEEE 802.16) networks. A scheduling scheme that satisfies QoS requirements has become more important for wireless communications. We propose a downlink scheduling scheme called adaptive priority-based downlink scheduling (APDS) for providing QoS guarantees in IEEE 802.16 networks. APDS comprises two major components: Priority assignment and resource allocation. Different service-type connections primarily depend on their QoS requirements to adjust priority assignments and dispatch bandwidth resources dynamically. We consider both starvation avoidance and resource management. Simulation results show that our APDS methodology outperforms the representative scheduling approaches in QoS satisfaction and maintains fairness in starvation prevention.

• Proceedings of the Safety Management and Science Conference
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• 2000.11a
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• pp.1-5
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• 2000

With the advent of the internet era, web-based virtual training system is gaining its importance in recent years. Because of the fact that the training can take place in any place and at any time, the virtual system is now replacing many of the conventional off-line classes. Hardware environments such as communication bandwidth and computer performance gets fast enough to accommodate the virtual education. Based on the observations on current virtual training system, this paper proposes three critical design rules required when developing a new virtual training system: i) With conceptual mapping, the menu hierarchy can be organized in a clear-cut manner, ii) Extensive use of multimedia tools can help students keep their attention to the lecture materials, and iii) Provision of interaction mechanisms helps students to gain their identity and motivation.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.426-433
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• 2002

This paper deals with an offline routing problem, which can be used as an explicit routing procedure in MPLS(Multiprotocol Label Switching) network, for traffic engineering. This problem is formulated as an MIP(Mixed Integer Programming) with the objective function which is to minimize the sum of the maximum link utilization for load balancing (link utilization) and the routing cost. Constraints arc composed of link capacity restriction and demand requirement that has origin-destination pair, bandwidth requirement and hop restriction. The problem is proved to be NP-hard so that the Lagrangean relaxation method is applied to propose a Lagrangean heuristic. To test the effectiveness & efficiency of the proposed algorithm, computational experiments are performed with numerical instances. The experiment results show that the proposed algorithm solves the problem within a reasonable time.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.120-127
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• 2002

The multicasting is defined as the distribution of the same information stream from one to many nodes concurrently. There has been an intensive research effort to design protocols and construct multicast routing graphs for a single multicast group. However. there have been few researches about the relation between multiple and concurrent multicast groups. In this paper, the multiple multicast tree allocation algorithm to avoid congestion is proposed. The multicast group with different bandwidth requirement is also considered. A two-phase algorithm is proposed. The first phase is for basic search and the second phase for further improvement. The performance of the proposed algorithm is experimented with computational results. Computational results show that the proposed algorithm outperforms an existing algorithm.