• The Journal of the Acoustical Society of Korea
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• v.29 no.1E
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• pp.11-27
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• 2010

Nowadays, ultrasound Doppler imaging is widely used in assessing cardiovascular functions in the human body. However, a major drawback of ultrasonic Doppler methods is that they can provide information on blood flow velocity along the ultrasound beam propagation direction only. Thus, the blood flow velocity is estimated differently depending on the angle between the ultrasound beam and the flow direction. In order to overcome this limitation, there have been many researches devoted to estimating both axial and lateral velocities. The purpose of this article is to survey various two-dimensional velocity estimation methods in the context of Doppler imaging. Some velocity vector estimation methods can also be applied to determine tissue motion as required in elastography. The discussion is mainly concerned with the case of estimating a two-dimensional in-plane velocity vector involving the axial and lateral directions.

• The Journal of the Acoustical Society of Korea
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• v.29 no.3E
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• pp.107-110
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• 2010

In this paper, the rationale and contents of the special issue of the Journal of the Acoustical Society of Korea regarding comprehensive reviews on past, present and future of biomedical ultrasound are described. Brief descriptions of invited articles are given, and efforts by all contributing authors are gratefully acknowledged.

• Journal of Korea Multimedia Society
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• v.19 no.2
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• pp.224-232
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• 2016

The methodology to visualize the shape of blood vessel and its blood flow have been attracting as a very interesting problem to forecast and examinate a disease in thrombus precursor protein. May previous visualization researches have been appeared for designing the blood vessel and also modeling the blood flow using a doppler imaging technique which is one of nondestructive testing techniques. General visualization methods are to depict the blood flow obtained from doppler effects with fragmentary stream lines and also visualize the blood flow model using volume rendering. However, these visualizeation techniques have the disadvantage which a set of small line segments does not give the overall observation of blood flows. Therefore, we propose a visualization system which reconstruct the continuity of the blood flow obtained from doppler effects and also visualize the blood flow with the vector field of blood particles. This system will use doppler phase difference from medical equipments such as OCT with low penetration and reconstruct the blood flow by the curvature estimation from vector field of each blood particle.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.7
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• pp.685-691
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• 2011

The aim of this study is to point out the uniqueness of Doppler optical coherence tomography (DOCT) for use in a probe station for (in vivo) visualization of microscale flow and structure and to maximize the effectiveness of DOCT by overcoming its limitations. Conventional DOCT produces images of only one of the velocity components that is parallel to the incident light. In this study, a multi-angle DOCT to quantify a velocity vector field is proposed; this is an extension from a velocity scalar field to a vector field. Quantifying an instantaneous three-dimensional velocity field in a pulsating flow is another challenge because of its limited frame rate. The in-vivo pulsating blood flow is measured by using an electrocardiogram-gated multi-angle DOCT in a hamster cheek pouch model. It is shown that the aliasing problem caused by a relatively low frame rate is resolved by using this method of measurement.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.429-434
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• 2002

The Synthetic Aperture Radar (SAR) data are considered to contain the greatest amount of information among various microwave techniques developed for measuring ocean variables from aircraft or satellites. They have the potential of measuring wavelength, wave direction and wave height of the ocean waves. But, it is difficult to retrieve significant ocean wave heights and surface current from conventional SAR data, since the imaging mechanism of ocean waves by a SAR is determined by the three basic modulation processes arise through the tilt modulation, hydrodynamic modulation and velocity bunching which are poorly known functions. Along-Track Interferometric (ATI) SAR systems can directly detect the Doppler shift associated with each pixel of a SAR image and have been used to estimate wave fields and surface currents. However, the Doppler shift is not simply proportional to the component of the mean surface current. It includes also contributions associated with the phase velocity of the Brags waves and orbital motions of all ocean waves that are longer than Brags waves. In this paper, we have developed a new method for extracting the surface current vector using multiple-frequency (L- & C-band) ATI SAR data, and have generated surface wave height information.