Jinkeun Hong

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High-grade narrowband speech security for high frequency (HF) transmissions can be achieved using low rate speech coders and encryption algorithms. This paper presents test results for an HF channel and the structure of a test system that uses a mixed excitation linear prediction (MELP) vocoder for digital plain and secure speech transmission. The system is(More)
The sinusoidal speech model represents a speech signal as a linear combination of sinusoids with time-varying parameters {amplitudes, frequencies, and phases}. However, one drawback of this model is that the analysis window width is generally fixed in analyzing the signal. Since each sinusoidal parameter has different frequencies, an analysis window with(More)
Sensor-medium access control (S-MAC) protocol is a well-known MAC protocols designed for wireless sensor networks (WSNs). In this paper, we examine security vulnerability in S-MAC and analyze the power consumed at each stage of S-MAC according to vulnerability of denial of service (DoS) attack. From our analytical results, it can be induced that there is a(More)