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In diagnostic ultrasound imaging the speed of sound is assumed to be 1540 m/s in soft tissues. When the actual speed is different, the mismatch can lead to distortions in the acquired images, and so reduce their clinical value. Therefore, the estimation of the true speed has been pursued not only because it enables image correction but also as a way of(More)
A turbulent boundary-layer flow over a rough wall generates a dipole sound field as the near-field hydrodynamic disturbances in the turbulent boundary-layer scatter into radiated sound at small surface irregularities. In this paper, phased microphone arrays are applied to the measurement and simulation of surface roughness noise. The radiated sound from two(More)
hchoi POSITION TITLE Research Fellow EDUCATION/TRAINING (Begin with baccalaureate or other initial professional education, such as nursing, and include postdoctoral training.) B. Selected peer-reviewed publications (in chronological order). Quantitative analysis of fentanyl in rat plasma by gas chromatography with nitrogen-phosphorous detection, Influence(More)
We propose a new adaptive filtering algorithm whose convergence rate is very fast even for a highly correlated input signal. It is well-known that convergence rate gets worse when the input signal to an adaptive filter is correlated. Introducing an orthogonal constraint between successive input signal vectors makes us overcome the slow convergence caused by(More)
Conventional beamforming used in pulse-echo ultrasound images results in an inherent blurring. This blurring limits the resolution, and hence the utility, of pulse-echo ultrasound in clinical applications. Ng et al. developed an expectation-maximisation algorithm to enhance blurred, two-dimensional RF ultrasound images. It is important that the algorithm is(More)
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