• Journal of information and communication convergence engineering
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• v.6 no.2
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• pp.146-149
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• 2008

Simulation and signal conditioning on the time domain surface elevation records are conducted to verify the proposed Welch's method in non-directional ocean wave spectrum analysis. These spectrum data are further conditioned to provide wave characteristic that better describe the sea states. Comparison of significant wave height and zero crossing period between the proposed method and a reference toolkit are presented.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.3
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• pp.229-238
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• 2016

In this paper, we have studied isolation enhancement using a suppression of surface wave to improve performance of array antenna. To reduce isolation between elements of array antenna, perfect magnetic conductor(PMC) and SOFT-surface is designed and located at center of ground plane, isolation and gain is simulated by commercial full wave simulator(HFSS). As a result, isolation of more than 40 dB and gain improvement of 2.2 dBi are obtained at E-plane array in case of both PMC and SOFT-surface. At H-plane array, air coupling is dominant compared to coupling by surface wave. It is conclude that this study is useful for design of compact array antenna and performance improvement of array antenna.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1986.10a
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• pp.16-19
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• 1986

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1985.10a
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• pp.41-44
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• 1985

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1985.10a
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• pp.123-128
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• 1985

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.363-368
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• 2001

Because of rapid damping of light and electromagnetic wave, acoustic wave has been widely used for underwater communication. However, the propagation of the acoustic wave is highly dependent on the environment such as water properties(temperature, pressure, salinity), bottom and surface conditions, etc.. This paper deals with the surface reflection effect on the wave propagation in the underwater anechoic basin in KRISO. Both theortical and experimental approaches are performed and the results are compared.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1988.10a
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• pp.118-121
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• 1988

Previous antenna design formula produce some errumenous resulitat the high frequency(above x-band.) This is because of the dispersion effect. Surface wave and higher order modes We propose exact design formula which gives errors less then 0.5% at the above x-band Exper imental investigations also prove the exactness of the proposed formual Further investigations should be done to give the relations between surface wave poles higer mides and resonant frequency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.609-611
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• 2013

There's little to obstacles obstructing communication in the sky. There are nearly fixed obstacles obstructing communication on the ground. But communication disruption can be occur frequently and unexpectedly on the sea surface. Especially, it is difficult for a small station which can be greatly affected by waves and low antenna height to secure the LOS for radio communication. In this paper, LOS and minimum antenna height is calculated due to changing wave height and Tx/Rx antenna height on the sea surface.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.3
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• pp.779-800
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• 2024

Unmanned Aerial Vehicle (UAV) networks, also known as drone networks, have gained significant attention for their potential in various applications, including communication. UAV networks for communication involve using a fleet of drones to establish wireless connectivity and provide communication services in areas where traditional infrastructure is lacking or disrupted. UAV communication networks need to be highly secured to ensure the technology's security and the users' safety. The proposed survey provides a comprehensive overview of the current state-of-the-art UAV network security solutions. In this paper, we analyze the existing literature on UAV security and identify the various types of attacks and the underlying vulnerabilities they exploit. Detailed mitigation techniques and countermeasures for the protection of UAVs are described in this paper. The survey focuses on the implementation of novel technologies like Q-learning, blockchain, IRS, and mmWave. This paper discusses network simulation tools that range in complexity, features, and programming capabilities. Finally, future research directions and challenges are highlighted.

• The Journal of the Acoustical Society of Korea
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• v.3 no.2
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• pp.13-22
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• 1984

A surface acoustic wave signal processing device using the silicon surface state is presented and shown capable of storing a reference signal and later correlating another signal with the stored reference. The device memory consists of the storage of the spatial 2k pattern of an acoustic wave as stored charges in the surface state of silicon surface. Results of experiments are presented which characterize the operation of device. Simpliied models for charging process and nonlinear acoustoelectric interactions based on consideration of single surface state at the surface of silicon The validity of simplified model has been qualitatibely confirmed with experimental results and the application of this device to aprogrammable matched filter of communication is considered.