• Nuclear Engineering and Technology
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• v.28 no.4
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• pp.390-396
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• 1996

Piping Systems are usually designed for thermal expansion loads based on uniform temperatures at each cross section. However, in lines with low flow rates such as surge lines and spray lines, large transverse temperature gradients have been observed, resulting in too types of additional thermal stresses : (1) local thermal gradient stresses which are independent of routing and supports and (2) gross bending stresses due to induced pipe curvature which are routing and support system dependent. This paper presents a simplified method for analyzing a PER surge line for stratified flow.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.10
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• pp.9-25
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• 1997

Personal Communication Networks will be composed of ATM-based broadband ISDN in the future. However, unlike the wired networks, many challenges will arise in the wireless communication service such as PCS. These callenges are frequency alteration of cell routing path, relatively very high error rate at transmission over the wireless interface, etc. Particularly, the alteration of cell routing path caused by handoff makes temporary deterioration of QoS. In this paper, the signaling flows of handoff scenarios which may occur on Personal Communication Networks are presented, and verified by Pertri-Net toolkit. In addition, the cell flow control scheme which minimizes the lagging gap between cells and maintains the cell sequence during handoff is proposed. The proposed scheme can be summarized as the differentiation of normal queue and handoff queue, and the cell flow control between these queues. For verification of the proposed scheme, we used two approaches, which are mathermatical manipulation and SLAM simulation.

• Journal of Advanced Navigation Technology
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• v.18 no.6
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• pp.594-599
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• 2014

The routinized wireless devices such as smart phone have promoted to expand the use of IEEE 802.11 groups. The challenge environments of the wireless network utilizes effectively and user-oriented seamless services that handover is the most desirable issues under the wireless circumstance. In data center software defined network (SDN) has provided the flow routing to reduce costs and complexities. Flow routing has directly offered control for network administrator and has given to reduce delay for users. Under the circumstance of being short of network facilities, SDNs give the virtualization of network environments and to support out of the isolation traffic conditions. It shows that the mechanism of handover makes sure seamless services for higher density of the network infrastructure which is SDN to support network service re-configurable.

• Journal of Korea Water Resources Association
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• v.50 no.12
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• pp.827-836
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• 2017

The most important parameters of the Muskingum method, widely used in hydrologic river routing, are the storage coefficient and the weighting factor. The Muskingum method does not consider the lateral inflow from the upstream to the downstream, but the lateral inflow actually occurs due to the rainfall on the watershed. As a result, it is very difficult to estimate the storage coefficient and the weighting factor by using the actual data of upstream and downstream. In this study, the flow without the lateral inflow was calculated from the river flow through the hydraulic flood routing by using the HEC-RAS one-dimensional unsteady flow model, and the method of the storage coefficient and the weighting factor calculation is presented. Considering that the storage coefficient relates to the travel time, the empirical travel time formulas used in the establishment of the domestic river basin plan were applied as the storage coefficient, and the simulation results were compared and analyzed. Finally, we have developed a formula for calculating the travel time considering the flow rate, and proposed a method to perform flood routing by updating the travel time according to the inflow change. The rise and fall process of the flow rate, the peak flow rate, and the peak time are well simulated when the travel time in consideration of the flow rate is applied as the storage coefficient.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.462-465
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• 2002

This paper presents a basic theory of information flow from single sending point to multiple receiving points, where new theories of algebraic system called "Hybrid Vector Space" and flow vector space play important roles. Based on the theory, a new algorithm for finding maximum homogenous information flow is proposed, where homogenous information flow means the flow of the same contents of information delivered to multiple clients at a time. Effective multi-routing algorithms fur tree-shape delivery rout search are presented.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.6
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• pp.302-310
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• 2002

This paper presents an application of a improved branch exchange (IBE) algorithm with a tie branch power (TBP) flow equation to solve the Optimal Routing problem for operation of a radial Power system including power distribution system. The main objective of the Optimal Routing problem usually is to minimize the network real power loss and to improve the voltage profile in the network. The new BE algorithm adopts newly designed methods which are composed by decision method of maximum loss reduction and new index of loss exchange in loop network Thus, the proposed algorithm in this paper can search the optimal topological structures of distribution feeders by changing the open/closed states of the sectionalizing and tie switches. The proposed algorithm has been evaluated with the practical IEEE 32, 69 bus test systems and KEPCO 148 bus test system to show favorable performance gained.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.10
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• pp.12-19
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• 1996

Many recent supercomputers employ a kind of switch-based multistage interconnection network architectrues (MINs) for constructing scalabel parallel compters. This paper proposed a new routing method, hybrid wormhole and virtual-cut through routing (HWCR) for the prevention of rapid performance degradation comming from a conflict in links usage at hot traffic situation. This HWCR through (VCT) for the fast removing temporal stagger, result in seamless flow of packet stream. When the blocked link is removed, wormhole routing is resumed. The HWCR method adopted a hierachical buffer scheme for improving the network performance and reducing the cost in BMINs. We could get optimum buffer size and communicatin latency through the computer simulation based on proposed HWCR, and the results were compared to those using wormhole and VCT.

• Journal of the Korea Society of Computer and Information
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• v.6 no.1
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• pp.74-81
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• 2001

In this paper. the architecture of a high-speed ATM router using ATM switch is studied and the performance of the high-speed ATM router is analyzed through simulation. The high-speed ATM router using ATM switch is able to reduce the load of router and the processing time of a packet in the router. The size of router buffers has been studied through simulation processes for the analysis of performance capacity in due course of making changes in routing time(RT), which is the performance capacity parameters of high-speed ATM routers, flow table size(FS), flow live time(FT) and input circuit efficiencies. The result of this study can be used as the source material for analyzing the suitability of equipment in upgrading networks and applying high-speed ATM routers by using ATM switches.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.1
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• pp.73-79
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• 2001

IP Switching is a new routing technology Proposed to improve the Performance of IP routers. Flow classification is one of the key issues in IP Switching. To achieve better performance, flow classification should be matched to the varying IP traffic and an IP switch should make use of its hardware switching resources as fully as possible. This paper proposes an dynamic flow classification method for IP Switching. By dynamically adjusting the values of its control parameters in response to the present usage of the hardware switching resources, this dynamic method can efficiently match the varying IP traffic and thus improve the performance of an IP switch.

• Journal of Communications and Networks
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• v.11 no.3
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• pp.297-305
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• 2009

Multiprotocol label switching (MPLS) networks require dynamic flow admission control to guarantee end-to-end quality of service (QoS) for each Internet protocol (IP) traffic flow. In this paper, we propose to tackle the joint routing and admission control problem for the IP traffic flows in MPLS networks without rerouting already admitted flows. We propose two mathematical programming models for this problem. The first model includes end-to-end delay constraints and the second one, end-to-end packet loss constraints. These end-to-end QoS constraints are imposed not only for the new traffic flow, but also for all already admitted flows in the network. The objective function of both models is to minimize the end-to-end delay for the new flow. Numerical results show that considering end-to-end delay (or packet loss) constraints for all flows has a small impact on the flow blocking rate. Moreover, we reduces significantly the mean end-to-end delay (or the mean packet loss rate) and the proposed approach is able to make its decision within 250 msec.