• Journal of the Korean Society of Industry Convergence
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• v.14 no.3
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• pp.121-125
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• 2011

EMTP-RV is the very powerful program to analyze the dynamic operation of the power system. To use this package in the large complex power system, it is very important to simplify the power system to simple equivalent network. In our study the 100 MVA STATCOM is placed at 345kV "MIGUM" which is the one of the 345kV substations of the Korean Electric Power System that is consist of more than 1000-bus. MIGUM substation is connected with 7 separated transmission lines to main Korean Electric power system. We developed a new method to simplify the network except the substation that we want to analysis. The power system outside the 345kV substation is modeled into the equivalent network. The loop network outside the substation can be modeled to simplified Thevenin equivalent network. The proposed method is applied to IEEE-14 Reliability Test System and the results shows the effectiveness of the method.

• Convergence Security Journal
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• v.14 no.2
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• pp.25-33
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• 2014

With the development of information and communication, public institutions and enterprises utilize the business continuity using the Internet and Intranet. In this environment, public institutions and enterprises is to be introduced the number of solutions and appliances equipment to protect the risk of leakage of inside information. However, this is also the perfect external network connection is not enough to prevent leakage of information. To overcome these separate internal and external networks are needed. In this paper, we constructed the physical and logical network separation is applied to the network using the virtualization and thus the network configuration and network technical review of the various schemes were proposed for the separation.

• Journal of the Institute of Convergence Signal Processing
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• v.13 no.4
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• pp.233-237
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• 2012

In this paper, We propose a control system which compensate a output of a main Neual Network using a RTDNN(Recurrent Time Delayed Neural Network) with a FLC(Fuzzy Logic Controller)After a learn of main neural network, it can occur a Over shoot or Under shoot from a disturbance or a load variations. In order to adjust above case, we used the fuzzy compensator to get an expected results. And the weight of main neural network can be changed with the result of learning a inverse model neural network of plant, so a expected dynamic characteristics of plant can be got. We can confirm good response characteristics of proposed neural network controller by the results of simulation.

• Convergence Security Journal
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• v.8 no.4
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• pp.51-56
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• 2008

A combination of VPNs and dial-up access, such as DSL and Cable, usually provides the cost-effective solution as the substitution of private networks on high-cost leased line. The business demand for high availability has increased with VPN spreading. This paper presents the schemes for a high availability of network access and a load balancing of network traffic in VPN gateways by using multiple links or multihoming capability based on active-active approach. The high availability and load balancing of network links can be achieved by duplicating external network access into multiple independent links. This can provide a continuous network connection to internal users even if one of the links is failed. Moreover, it can provide twice network bandwidth by distributing the traffic into the links. Static and dynamic algorithms are proposed as the load balancing algorithms.

• ETRI Journal
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• v.27 no.4
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• pp.355-366
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• 2005

Automatic discovery of physical topology plays a crucial role in enhancing the manageability of modern metro Ethernet networks. Despite the importance of the problem, earlier research and commercial network management tools have typically concentrated on either discovering logical topology, or proprietary solutions targeting specific product families. Recent works have demonstrated that network topology can be determined using the standard simple network management protocol (SNMP) management information base (MIB), but these algorithms depend on address forwarding table (AFT) entries and can find only spanning tree paths in an Ethernet mesh network. A previous work by Breibart et al. requires that AFT entries be complete; however, that can be a risky assumption in a realistic Ethernet mesh network. In this paper, we have proposed a new physical topology discovery algorithm which works without complete knowledge of AFT entries. Our algorithm can discover a complete physical topology including inactive interfaces eliminated by the spanning tree protocol in metro Ethernet networks. The effectiveness of the algorithm is demonstrated by implementation.

• Journal of Convergence Society for SMB
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• v.4 no.4
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• pp.1-6
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• 2014

A wireless sensor network is being actively researched around the world that are connected to the mesh are a plurality of sensor nodes in a wireless manner that span different regions of the techniques. However, wireless communications use the limitation of resources, so it is very weak due to the properties of the network itself secure in comparison to the normal network. Wireless sensor network is divided into tapped-based attacks, forgery based attacks, denial of service attacks based largely by securities laws must defend against various attacks such as insertion of the wrong information being sent eavesdropping or modification of information, which is usually sensor network applications need to do. The countermeasure of sensor network attack is described in this research, and it will contribute to establish a secure sensor network communication.

• Journal of the Institute of Convergence Signal Processing
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• v.3 no.1
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• pp.54-60
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• 2002

In this paper, we proposed a hybrid neural network-fuzzy controller which compensate a output of neural network controller. Even if learn by neural network controller, it can occur an bad results from disturbance or load variations. So in order to adjust above case, we used the fuzzy compensator to get an expected results. And the weight of main neural network can be changed with the result of loaming a inverse model neural network of Plant, so a expected dynamic characteristics of plant can be got. As the results of simulation through the second order plant, we confirmed that the proposed speed controller get a good response compare with a neural network controller. We implemented the controller using the DSP processor and applied in a hydraulic servo system. And then we observed an experimental results.

• Convergence Security Journal
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• v.23 no.2
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• pp.3-10
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• 2023

In the malware distribution network existing on the web, there is a central node that plays a key role in distributing malware. If you find and block this node, you can effectively block the propagation of malware. In this study, a centrality search method applied with risk analysis in a complex network is proposed, and a method for finding a core node in a malware distribution network is introduced through this approach. In addition, there is a big difference between a benign network and a malicious network in terms of in-degree and out-degree, and also in terms of network layout. Through these characteristics, we can discriminate between malicious and benign networks.

• Journal of Advanced Navigation Technology
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• v.21 no.4
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• pp.402-412
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• 2017

The convergence of broadcasting and telecommunication technologies is a key issue of the ubiquitous networks. So this paper offers the convergence of integrated telecommunication networks and broadcasting system, Advanced Terrestrial Digital Multimedia Broadcasting (AT-DMB), and the interconnection of them via the Media Independent Information Server/Service (MIIS). Then, this paper proposes the fast wakeup and connection mechanism with concepts for improving QoS and energy efficiency simultaneously. In the proposed convergence network, our mechanism places the key on the minimization of both the incoming service delay destined to a turned-off interface by using the broadcasting network and the additional energy consumption. This paper further evaluates the performance of proposed mechanism through the numerical and experimental analysis and has confirmed the decrease of both service delay and energy consumption.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.9
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• pp.1686-1692
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• 2015

This paper proposes a modified genetic algorithm that has the same beamforming performance and a fast convergence speed using general genetic algorithm in order to form a beam for the mobile node in a mesh network. The proposed beamforming genetic algorithm selects a part of chromosome a high fitness value in mating process to obtain fast convergence speed, and rest part of chromosome with longer fitness value in order to avoid local solution. Furthermore, the reference beam pattern with Gaussian shape reduces additional convergence speed. Simulation shows that the convergence speed of proposed algorithm improves 20% compared with that of conventional beamforming genetic algorithm.