• Journal of Advanced Navigation Technology
• /
• v.18 no.6
• /
• pp.594-599
• /
• 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 the Korean Society for Precision Engineering
• /
• v.15 no.4
• /
• pp.83-90
• /
• 1998

In this paper, we present neural network for control of Left Ventricular Assist Device(LVAD) system with a pneumatically driven mock circulation system. Beat rate(BR), Systole-Diastole Rate(SDR) and flow rate are collected as the main variables of the LVAD system. System modeling is completed using the neural network with input variables(BR, SBR, their derivatives, actual flow) and output variable(actual flow). It is necessary to apply high perfomance control techniques, since the LVAD system represent nonlinear and time-varing characteristics. Fortunately. the neural network can be applied to control of a nonlinear dynamic system by learning capability In this study, we identify the LVAD system with neural network and control the LVAD system by PID controller and neural network feedforward controller. The ability and effectiveness of controlling the LVAD system using the proposed algorithm will be demonstrated by experiment.

• ETRI Journal
• /
• v.34 no.6
• /
• pp.827-837
• /
• 2012

We propose a flow admission control (FAC) for setting up a wire-speed connection for new flows based on their negotiated bandwidth. It also terminates a flow that does not have a packet transmitted within a certain period determined by the users. The FAC can be used to provide a reliable transmission of user datagram and transmission control protocol applications. If the period of flows can be set to a short time period, we can monitor active flows that carry a packet over networks during the flow period. Such powerful flow management can also be applied to security systems to detect a denial-of-service attack. We implement a network processor called a flow management network processor (FMNP), which is the second generation of the device that supports FAC. It has forty reduced instruction set computer core processors optimized for packet processing. It is fabricated in 65-nm CMOS technology and has a 40-Gbps process performance. We prove that a flow router equipped with an FMNP is better than legacy systems in terms of throughput and packet loss.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.9
• /
• pp.39-48
• /
• 2008

Recently, many multimedia services have emerged in Internet such as real-time and non- real time services. However, in this Internet environment, we have some limitations to satisfy each service feature. To guarantee the service features in Measurement-Based Admission Control(MBAC) based system on the flow-aware network, there is the method applying Dynamic Priority Scheduling(DPS) algorithm that gives a higher priority to an earlier incoming flow in all of the link bandwidth. This paper classifies all flows under several groups according to flow characteristics on per-flow MBAC algorithm based system. In each flow group, DPS algorithm is applied. This paper proposes two methods that are a DPS based bandwidth borrowing method and a bandwidth dynamic allocation method. The former is that if low priority class has available bandwidths, the flow of high priority class borrows the bandwidth of low priority class when high priority flow has insufficient bandwidth to connect a flow call. The later is that the each group has a minimum bandwidth and is allocated the bandwidth dynamically according to the excess rate for available bandwidth. We compare and analyze the characteristics of the two proposed methods through the simulation experiments. As the results of the experiment, the proposed methods are more effective than existing DPS based method on the packet loss and delay characteristics. Consequently the proposed two methods are very useful in various multimedia network environments.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.21 no.2
• /
• pp.447-460
• /
• 1996

Network optimization and design procedures often separate quality of service (QOS) performance measures from reliability issues. This paper considers channel allocation and flow assignment (routing) in a network subject to link failures. Fault-tolerant channel allocation and flow assingments are determined which minimize network cost while maintaining QOS performance requirements. this approach is shown to yield significant network cost reductions compared to previous heuristic methods used in the design of packet switched network with unreliable links.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.9 no.8
• /
• pp.1683-1690
• /
• 2005

This study examines dynamic flow control method in UDP, analyzes packet loss which is frequently used element in measuring existing dynamic flow control and characteristics of round trip time, and proposes a new method of measurement, RSST. The algorithm that uses the proposed RSST enables accurate measurement of network status by considering both the currently measured network status and the past history of network status in controlling the transmission rate. For comparison study, a network status measurement software program that displays detailed information about volume of transmission generation of network status, and flow pattern of network was developed. The performance test shows that the proposed algorithm can better adjust to network condition in terms of low pack loss rate over existing algorithms.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2018.01a
• /
• pp.43-44
• /
• 2018

SDN(Software Defined Network)는 데이터 부분과 컨트롤 부분을 분리하여 하나의 컨트롤러가 모든 데이터를 담당하는 기술이다. SDN에서 표준 프로토콜 역할을 하는 OpenFlow가 있으며 컨트롤러가 이 OpenFlow 프로토콜을 사용하여 Flow 테이블의 항목을 추가하고 삭제하도록 OpenFlow 스위치를 제어한다. OpneFlow 스위치는 하나 이상의 Flow table을 사용하여 조회하고 채널을 톨해 컨트롤러에 전달한다. 본 논문에서는 Flow Entry 구성도와 Flow가 Flow table에 도달하는 확률, Flow Entry를 분류하는 Vacancy에 대해 설명하였다.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.19 no.40
• /
• pp.263-269
• /
• 1996

The most vital arc in the maximum flow problem is that arc whose removal results in the greatest reduction in the value of the maximal flow between a source node and a sink node. This paper develops an algorithm to determine such a most vital arc(MVA) in the maximum flow problem. We first define the transformed network corresponding In a given network in order to compute the minimal capacity for each candidate arc. The set of candidate arcs for a MVA consists of the arcs whose flow is at least as greate as the flow over every arc in a minimal cut As a result, we present a method in which the MVA is determined more easily by computing the minimal capacity in the transformed network. The proposed method is demonstrated by numerical example.

• Communications for Statistical Applications and Methods
• /
• v.9 no.3
• /
• pp.845-851
• /
• 2002

An efficient method is developed to obtain the maximum flow for a network when its simple paths are known. Most of the existing techniques need to convert simple paths into minimal cuts, or to determine the order of simple paths to be applied in the process to reach the correct result. In this paper, we propose a method based on the concepts of signed simple path and signed flow defined in the text. Our method involves a fewer number of arithmetic operations at each iteration, and requires fewer iterations in the whole process than the existing methods. Our method can be easily extended to a mixed network with a slight modification. Furthermore, the correctness of our method does not depend on the order of simple paths to be applied in the process.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.25 no.2
• /
• pp.115-124
• /
• 2000

The most vital arc in the maximum flow problem is that arc whose removal results in the greatest reduction in the value of the maximal flow between a source node and a sink node. This paper develops an algorithm to determine such a most vital arc in the maximum flow problem. We first define the transformed network corresponding to a given network in order to compute the minimal capacity for each candidate arc. The set of candidate arcs for single most vital arc consists of the arcs whose flow is at least as great as the flow over every arc in a minimal cut. As a result we present a method in which the most vital arc is determined more easily by computing the minimal capacity in the transformed network. the proposed method is demonstrated by numerical example and computational experiment.