• The Transactions of the Korea Information Processing Society
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• v.6 no.3
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• pp.722-728
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• 1999

When one link failure happens in BSHR/2 networks, it is possible to restore all traffics by following the ITU-T G.841 rules. However, when a node that is currently executing a ring switch receives a long-path ring bridge request for an higher priority, it shall drop its bridge and switch immediately, then enter full pass-through. Even through link connection between two nodes exists, it is impossible to restore the service. In this paper, when multi-link failures happen, the services through connected link can be restored by exchanging messages through DCC(Data Communication Channel). Partially reconstructing the ring map that is unable to restore services because of multi-link failures made it possible to restore these kinds of traffic pattenrs. This paper shows that the services through connected link can be restored by using proposed method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.756-765
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• 2001

An effective dexterous motion control method of redundant robot manipulators based on neural optimization network is proposed to satisfy multi-criteria such as singularity avoidance, minimizing energy consumption, and avoiding physical limits of actuator, while performing a given task. The method employs a neural optimization network with parallel processing capability, where only a simple geometric analysis for resolved motion of each joint is required instead of computing of the Jacobian and its pseudo inverse matrix. For dexterous motion, a joint geometric manipulability measure(JGMM) is proposed. JGMM evaluates a contribution of each joint differential motion in enlarging the length of the shortest axis among principal axes of the manipulability ellipsoid volume approximately obtained by a geometric analysis. Redundant robot manipulators is then controlled by neural optimization networks in such a way that 1) linear combination of the resolved motion by each joint differential motion should be equal to the desired velocity, 2) physical limits of joints are not violated, and 3) weighted sum of the square of each differential joint motion is minimized where weightings are adjusted by JGMM. To show the validity of the proposed method, several numerical examples are illustrated.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.709-712
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• 2004

The BcN is applying from public networks to local networks and each terminal step by step under supporting MIC(Ministry of Information and Communication Repoblic of Korea) until 2007. The architecture of network sorority should considers BcN environment and evolves to manage Ipv6 traffics. The next generation network security architecture can manage not only Ipv6 environment but also wire and wireless integrated network. We suggest the next generation network security architecture for Ipv6 environment and wire-wireless integrated network environment and verify the performance of the suggested architecture using network security scenario.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.7
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• pp.1561-1567
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• 2015

Nodes of Mobile ad-hoc network usually use the energy-limited battery. Balanced energy consumptionis important to maintain path's stability. In this paper, we focus on improving the stability of the routing path in mobile ad-hoc networks. For that purpose, we propose a new routing protocol to find the highest minimum node residual energy path among shortest paths. The largest path of minimum value of the remain energy has a longer life than other paths to improve the reliability to data-transmission. Using ns-3 simulator, we show that the proposed routing protocol can provide more long-life stable routing path than AODV and EA-AODV.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.5
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• pp.109-116
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• 2016

Today various IoT platforms exist, but most of them only consider IPv6, without other types of network including private network. They support, therefore, the private network to use virtual private network or through the hardware gateway. To solve this limitation, we propose a IoT platform that provides IoT Services on private networks. Also we verify this platform though constructing a testbed.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.4
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• pp.97-106
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• 2014

In this paper, we propose a design method to extend certain cognitive radio (CR) MAC protocols originally proposed only for the one hop applications in distributed CR networks to MANET routing protocols. Among several CR MAC protocols, the opportunistic MAC (called O-MAC) and the opportunistic period MAC (called OP-MAC) are considered, and AODV as MANET routing protocol is used. We implement the protocols using OPNET network simulator, and compare the performances in both MAC and AODV routing environments. With the experiments, we analyze the relationship between MAC and routing performances of the CR protocols.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.3
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• pp.125-132
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• 2013

In this paper, We send DDoS(Distributed Denial of Service) attack traffic to real homepages in real networks. We analyze the results of DDoS attack and propose mitigation method against DDoS Attacks. In order to analyze the results of DDoS Attacks, We group three defense level by administrative subjects: Top level defense, Middle level defense, Bottom level defense. Also We group four attack methods by feature. We describe the results that average of attack success rate on defense level and average of attack success rate on attack categories about 48ea homepages and 2ea exceptional cases. Finally, We propose mitigation method against DDoS attack.

• The Transactions of the Korea Information Processing Society
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• v.6 no.2
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• pp.439-448
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• 1999

In this paper, two optimization algorithms based on artificial neural networks and genetic algorithms are proposed for cellular radio channel assignment problems. The channel assignment process is characterized as minimization of the energy function which represents constraints of the channel assignment problems. All three constraints such as the co-channel constraint, the adjacent channel constraint and the co-site channel constraint are considered. In the neural networks approach, certain techniques such as the forced assignment and the changing cell order are developed, and in the genetic algorithms approach, data structure and proper genetic operators are developed to find optimal solutions, As simulation results, the convergence rates of the two approaches are presented and compared.

• Journal of Communications and Networks
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• v.4 no.3
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• pp.230-245
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• 2002

Usually the network-throughput maximization problem for constant-bit-rate (CBR) circuit-switched traffic is posed for a fixed offered load profile. Then choices of routes and of admission control policies are sought to achieve maximum throughput (usually under QoS constraints). However, similarly to the notion of channel “capacity,” it is also of interest to determine the “network capacity;” i.e., for a given network we would like to know the maximum throughput it can deliver (again subject to specified QoS constraints) if the appropriate traffic load is supplied. Thus, in addition to determining routes and admission controls, we would like to specify the vector of offered loads between each source/destination pair that “achieves capacity.” Since the combined problem of choosing all three parameters (i.e., offered load, admission control, and routing) is too complex to address, we consider here only the optimal determination of offered load for given routing and admission control policies. We provide an off-line algorithm, which is based on Lagrangian techniques that perform robustly in this rigorously formulated nonlinear optimization problem with nonlinear constraints. We demonstrate that significant improvement is obtained, as compared with simple uniform loading schemes, and that fairness mechanisms can be incorporated with little loss in overall throughput.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.8
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• pp.2436-2448
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• 1996

This paper presents the development of three types of network performance manager for IEEE 802.4 token bus networks that are a part of Manufacturing Automation Protocol(MAP). The performance managers attempt to keep the average data latency below a certain level specified for each priority class. All of the three performance managers are based on a set of fuzzy rules incorporating the knowledge on the relationship between data latency and parameters of the priority mechanism. These Fuzzy Network Performance Managers(FNPMs) have been evaluated via discrete event simulation to demonstrate their efficacy.