• Convergence Security Journal
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• v.14 no.2
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• pp.43-50
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• 2014

Recently, lot of researches for the multi-level protocol have been done to balance the sensor node energy consumption of WSN and improve the node efficiency to extend the life of the entire network. Especially in multi-hop protocol, a variety of models have been proposed to improve energy efficiency and apply it to WSN protocol. In this paper, we analyze LEACH algorithm and propose new method based on center of local clustering routing algorithm in wireless sensor networks. We also perform NS-2 simulation to show the performance of our model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5496-5505
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• 2012

As the IT industry develops, the smart-phone technology and functions which are actively being studied at the moment greatly influence the entire living environment. With the smart-phone technology and functions, people's interest for the wireless LAN which can be used to get access to the Internet anytime anywhere is gradually increasing. However, since the malicious attacker can easily carry out hacking or approach the contents due to the characteristics of the wireless radio wave, the personal information with a high level of importance for data security is easily exposed due to Spoofing, Denial of Service attack and Man in the Middle attack. Therefore, the demand for security is gradually increasing. In this paper, the safe wireless network service environment is provided by supplementing the vulnerability in regard to Spoofing, Session Hijacking and Man in the Middle attack after executing the client's authentication process, the AP authentication process and the Mobile Agency authentication process with the client's information in the USIM, the AP information and the Mobile Agency information when the client uses the wireless Internet through the Mobile Agency AP access in the smart phone environment.

• Journal of Digital Convergence
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• v.19 no.7
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• pp.209-215
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• 2021

This study is a system development for voice information protection equipment in major meetings and places requiring security. Security performance and stability were secured with information leakage prevention technology through generation of false noise and ultrasonic waves. The cutoff frequency band for blocking the leakage of voice information, which has strong straightness due to the nature of the radio wave to the recording prevention module, blocks the wideband frequency of 20~20,000Hz, and the deception jamming technology is applied to block the leakage of voice information, greatly improving the security. To solve this problem, we developed a system that blocks the recording of a portable smartphone using a battery, and made the installation of a separate device smaller and lighter so that customers do not recognize it. In addition, it is necessary to continuously study measures and countermeasures for efficiently using the output of the anti-recording speaker for long-distance recording prevention.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.4
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• pp.397-403
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• 2015

In this paper, a method of ISAR geometric calibration is represented by using impulse-radio UWB radar. The ir-UWB is good for using a signal processing in time domain, so, it does not occur a multi-path or coupling problem. If a signal that between antennas and target is assumed a plane wave, a center of rotation in ISAR geometry model can be estimated by using point target. Before image is reconstructed with sinogram, the center of rotation can be calculated by using least square fitting. This method can be obtained a more contrast image, and a maximum value of entropy of image. The method, that estimates a center of rotation in received data, will be used a initial setup of instruments or a periodic compensation to reconstruct image. It would be useful in medical, security and surveillance imaging equipments that have a fixed geometry.

• Journal of Satellite, Information and Communications
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• v.9 no.3
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• pp.1-4
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• 2014

A radio communication system has interference caused by other radio transmitters operated in co-channel or adjacent channels. Therefore technical specifications are made by considering and investigating the effects of interference between the new system and present systems when the new system will be started to serve in the near future. FTS is used for preventing an abnormal mission and guaranteeing public protection. Recently the next generation FTS's are researched to reinforce the security and to increase the operating capability of simultaneous use. EFTS known as one of the next generation FTS's is suitable for such purposes. In this paper the effects of interference signals on the performance of EFTS are investigated. Noncoherent DPSK and noncoherent CPFSK are considered for the modulation method of EFTS and a FMCW and a pulse RADAR considered as a interferer. The power of FMCW is 20.3dB lower than the power of EFTS and the power of pulse RADAR is 19.1dB lower than that of EFTS. Simulation results show that FMCW interferer reduce $E_b/N_o$ of about 1dB and $E_b/N_o$ of EFTS deteriorates about 0.5dB due to interference signals generated from pulse RADAR.