• The Magazine of the IEIE
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• v.22 no.10
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• pp.52-62
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• 1995

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.6
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• pp.1225-1234
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• 2019

The security of the firmware is more important because embedded devices have become popular. Network devices such as routers can be attacked by attackers through web application vulnerabilities in embedded firmware. Therefore, they must be found and removed quickly. The Firmadyne framework proposes a dynamic analysis method to find vulnerabilities after emulating firmware. However, it only performs vulnerability checks according to the analysis methods defined in the tool, thus limiting the scope of vulnerabilities that can be found. In this paper, fuzzing is performed in emulation-based environment through fuzzing, one of the software security test techniques. We also propose a Fabfuzz tool for efficient emulation based fuzzing. Experiments have shown that in addition to the vulnerabilities identified in existing tools, other types of vulnerabilities have been found.

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.6
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• pp.357-366
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• 2013

Spectrum sensing, as a fundamental functionality of Cognitive Radio (CR), enables Secondary Users (SUs) to monitor the spectrum and detect spectrum holes that could be used. Recently, the security issues of Cognitive Radio Networks (CRNs) have attracted increasing research attention. As one of the attacks against CRNs, a Primary User Emulation (PUE) attack compromises the spectrum sensing of CR, where an attacker monopolizes the spectrum holes by impersonating the Primary User (PU) to prevent SUs from accessing the idle frequency bands. Energy detection is often used to sense the spectrum in CRNs, but the presence of PUE attack has not been considered. This study examined the effect of PUE attack on the performance of energy detection-based spectrum sensing technique. In the proposed protocol, the stationary helper nodes (HNs) are deployed in multiple stages and distributed over the coverage area of the PUs to deliver spectrum status information to the next stage of HNs and to SUs. On the other hand, the first stage of HNs is also responsible for inferring the existence of the PU based on the energy detection technique. In addition, this system provides the detection threshold under the constraints imposed on the probabilities of a miss detection and false alarm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4B
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• pp.224-231
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• 2008

EPONs are a low cost, high speed solution to the bottleneck problem of broadband access networks. To support point-to-point and shared LAN emulation, EPONs use the multi-point control protocol (MPCP), which uses logical link identification (LLID) for frame tagging and filtering between the OLT and ONUs. In this paper, ONU-based multicast or multiple shared LAN emulation is used for IPTV channel package delivery services. Using ONU-based VLAN services, EPONs can support separate and secure connections between providers and subscribers in a simple manner. Also, IPTV channel packages can be delivered through EPONs by implementing ONU-based VLAN and IGMP snooping mechanisms. By showing fast channel zapping time of proposed architecture, I show that EPONs is suitable for IPTV channel package delivery service.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.3
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• pp.266-273
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• 2003

A wind turbine simulator is developed for the emulation of variable input torque from the wind energy without actual rotor blades using motor-generator set. The torque command of dc motor is calculated from the characteristic equation of rotor blade during the change of wind speed. Especially the proposed control algorithm takes into account the fact that the moment of inertia of blade is much larger than that of driving motor. If you select the desired value of inertia, the stored/restored energy of the inertia during acceleration/deceleration can be compensated effectively resulting the only net torque is delivered to the generator. The simulator set-up has been designed and implemented using a do motor and drive. Feasibility of the proposed algorithm is verified by computer simulations and experiments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.3
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• pp.1313-1336
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• 2020

Cognitive radio (CR) is regarded as an effective approach to avoid the inefficient use of spectrum. However, CRNs have more special security problems compared with the traditional wireless communication systems due to its open and dynamic characteristics. Primary user emulation attack (PUEA) is a common method which can hinder secondary users (SUs) from accessing the spectrum by transmitting signals who has the similar characteristics of the primary users' (PUs) signals, and then the SUs' quality of service (QoS) cannot be guaranteed. To handle this issue, we first design a multiple-phase energy detection scheme based on the cooperation of multiple SUs to detect the PUEA more precisely. Second, a joint SUs scheduling and power allocation scheme is proposed to maximize the weighted effective capacity of multiple SUs with a constraint of the average interference to the PU. The simulation results show that the proposed method can effectively improve the effective capacity of the secondary users compared with the traditional overlay scheme which cannot be aware of the existence of PUEA. Also the good delay QoS guarantee for the secondary users is provided.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.209-214
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• 2016

IEC 61850 is a protocol used to reduce the cost of design, installation and maintenance of the Substation Automation System. GOOSE traffic used in IEC 61850 plays an important role for control, protection and automation of the substation. This study implemented a GOOSE traffic generator using the emulation function of NS-3 network simulator, by using protocols provided by a network simulator and another protocols provided by real communication equipment. The generated GOOSE traffic was analyzed with Wireshark, and it was found that the traffic was generated exactly as expected. Besides, this study measured the GOOSE traffic delay due to the increase of the number of switches according to network topology. It is expected that the GOOSE traffic generator implemented by this study will be efficiently used when experiments are performed on actual substation environments.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.225-230
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• 2015

This study presents a method for generating IEC 61850 Sampled Values(SV) traffic by combining the emulation function of network simulator ns-3 with the actual communication equipment. For the SV traffic generation and reception, the emulation function of the network simulator ns-3 is used, while as a communication network, the actual communication equipment, switches are used. In addition, the SV traffic frames generated are analyzed, using Wireshark, and it is confirmed that the SV traffic frames are generated accurately. The method for the SV traffic generation proposed in the present study will be very useful when various SV traffics are generated under the environment of an actual substation.

• 한국게임학회지
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• v.6 no.1
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• pp.15-25
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• 2009

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.182.2-182.2
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• 2010

A various algorism has been studied to extract possibly every energy from a wind turbine in conjunction with the increase of concern about wind power system. In order to verify these control algorism, it is essential to make the most similar conditions to the real wind turbine's environment. Therefore, using separately excited DC motor a wind turbine the most similar to the real turbine is simulated. Tower shadow effect and Wind shear effect are considered as well as inertia emulation. For the control of Back-to-Back Converter Vector current control methods and space vector pulse width modulation are used and for reducing THD of grid current LCL filter is considered. This simulation results verified the energy produced by wind all flows into the utility under the consideration of the characteristics of a wind turbine. The result of this paper is expected to be used as a basic material for analyzing the characteristics of the wind turbine generator.