• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.1
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• pp.484-510
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• 2017

Network security is rapidly developing, but so are attack methods. Network worms are one of the most widely used attack methods and have are able to propagate quickly. As an active defense approach to network worms, the honeynet technique has long been limited by the closed architecture of traditional network devices. In this paper, we propose a closed loop defense system of worms based on a Software-Defined Networking (SDN) technology, called Worm-Hunter. The flexibility of SDN in network building is introduced to structure the network infrastructures of Worm-Hunter. By using well-designed flow tables, Worm-Hunter is able to easily deploy different honeynet systems with different network structures and dynamically. When anomalous traffic is detected by the analyzer in Worm-Hunter, it can be redirected into the honeynet and then safely analyzed. Throughout the process, attackers will not be aware that they are caught, and all of the attack behavior is recorded in the system for further analysis. Finally, we verify the system via experiments. The experiments show that Worm-Hunter is able to build multiple honeynet systems on one physical platform. Meanwhile, all of the honeynet systems with the same topology operate without interference.

• Journal of Power Electronics
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• v.11 no.3
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• pp.279-284
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• 2011

Network-based controls for ac motor drive systems are becoming increasingly important. In this paper, an ac motor control system is implemented by a motor control module and three sensor modules such as a voltage sensor module, a current sensor module, and an encoder module. There will inevitably be network time delays from the sensor modules to the motor control system, which often degrades and even destabilizes the motor drive system. As a result, it becomes very difficult to estimate the network delayed ac sensor data. An algorithm to reduce the effects of network time delays on sensor data is proposed, using both a synchronization signal and a simple method for estimating the sensor data. The algorithm is applied to a vector controlled induction motor drive system, and the performance of the proposed algorithm is verified with experiments.

• Journal of the Korea Society of Computer and Information
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• v.18 no.12
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• pp.113-121
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• 2013

In this paper, we design and implement a network weather map system, which provides a macroscopic view on the whole network topology as well as the network link status and utilization. The proposed system also provides distributed NetFlow-based database facility and Web-based query interface, through which network operators can check the detailed network router or link status as well as submit predefined queries to easily find out and locate heavy hitters and/or their usage. We believe that our develop system will be a useful tool for small-to-mid-scale ISPs or network operators, in managing their own networks in a cost-effective way.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2101-2105
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• 2003

Recently the number of Internet users has very sharply increased, and the number of intrusions has also increased very much. Consequently, security products are being developed and adapted to prevent systems and networks from being hacked and intruded. Even if security products are adapted, however, hackers can still attack a system and get a special authorization because the security products cannot prevent a system and network from every instance of hacking and intrusion. Therefore, the researchers have focused on an active hacking prevention method, and they have tried to develop a traceback system that can find the real location of an attacker. At present, however, because of the characteristics of Internet - diversity, anonymity - the real-time traceback is very difficult. To over-come this problem the Network-based Real-Time Connection Traceback System (NRCTS) was proposed. But there is a security problem that the victim system can be hacked during the traceback. So, in this paper, we propose modified NRCTS with connection redirection technique. We call this traceback system as Connection Redirected Network-based Real-Time Connection Traceback System (CR-NRCTS).

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.165-166
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• 2006

Recently, after Wide Area Outage of the North-Eastern United States occurred, many countries started to be concerned about WAMS (Wide Area Monitoring System), and Korean power system also experienced Wide Area outage according to typhoon Mae-Mi, and Haenam-Jeju HVDC line fault. Since it is too difficult to detect a symptom based on SCADA or EMS, a defense system of electric power infrastructure has required. In this research, the designed and developed system processes the time synchronized real time power system information based on GPS and shows the 2D/3D monitoring viewer using the phasor data and the results of three algorithms.

• Journal of information and communication convergence engineering
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• v.16 no.3
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• pp.160-165
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• 2018

This paper designed and developed the image processing system of integrating feature extraction and matching by using convolutional neural network (CNN), rather than relying on the simple method of processing feature extraction and matching separately in the image processing of conventional image recognition system. To implement it, the proposed system enables CNN to operate and analyze the performance of conventional image processing system. This system extracts the features of an image using CNN and then learns them by the neural network. The proposed system showed 84% accuracy of recognition. The proposed system is a model of recognizing learned images by deep learning. Therefore, it can run in batch and work easily under any platform (including embedded platform) that can read all kinds of files anytime. Also, it does not require the implementing of feature extraction algorithm and matching algorithm therefore it can save time and it is efficient. As a result, it can be widely used as an image recognition program.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.11
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• pp.497-505
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• 2001

The power system stabilizer(PSS) is important for the suppression of low-frequency oscillation and the improvement of system stability. In this paper, An Adaptive Neurofuzzy-based Power System Stabilizer(ANF PSS) is proposed as the new PSS type. The proposed PSS employs a multi-layer adaptive network. The network is trained directly from the input and the output of the generating unit. The algorithm combines the advantages of the Artificial Neural Network(ANN) and Fuzzy Logic Control(FLC) schemes. Studies show that the proposed ANF PSS can provide good damping of the power system over the wide range of operating conditions and improve the dynamic performance of the system.

• Journal of Power System Engineering
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• v.11 no.1
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• pp.28-32
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• 2007

This research proposed that development of wireless condition monitoring system using WLAN network. It offers the prospect of improved performance that removed a current a coaxial cable and reduced overall cost of condition monitoring. Recently, there is an interesting concern for wireless system as an infrastructure technology construct ubiquitous computing environment in the future. High performance computing board makes minimization with integrate of a various functions which support wireless LAN network. Instead of wired coaxial cable using measurement system in industry, wireless LAN network assists industry automation and engineer's convenience. Developed system adapted wireless LAN network on shipboard with engine room and deck house, it also executes wireless measurement test on 8500TEU containership.

• Nuclear Engineering and Technology
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• v.41 no.6
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• pp.807-812
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• 2009

An ICRF discharge cleaning and a fast wave electron heating experiment were performed. For automated operation and providing the diagnostics of the ICRF system, the ICRF local network was designed and implemented. This internal network provides monitoring, RF protection, remote control, and RF diagnostics. All the functions of the control system were realized by customized DSP units. The DSP units were tied by a local network in parallel. Owing to the distributed feature of the control system, the ICRF local control system is quite flexible to maintain. Developing the subsystem is a more effective approach compared to developing a large controller that governs the entire system. During the first experimental campaign of the KSTAR tokamak, the control system operated as expected without any major problems that would affect the tokamak operation. The transmitter was protected from harmful over-voltage events through reliable operation of the system.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.903-907
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• 2004

This paper introduces LnCP(Living Network Control Protocol)-based home network system and proposes high level message which is utilized between LnCP Home network Server and User Control Point. LnCP is very optimized protocol for digital home appliances. Then proposed system and implementation of these ideas are presented.