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

• The Journal of Korean Orthopaedic Ultrasound Society
• /
• v.5 no.2
• /
• pp.94-98
• /
• 2012

Calcific tendinitis is characterized by inflammation around calcium hydroxyapatite crystal deposits. Minimally invasive extracorporeal shock wave therapy (ESWT) has been postulated to be an effective treatment option for treating calcific tendinitis. In clinical practice, shock waves usually are aimed at the painful area after palpation and not focused. It has been known that exact fluoroscopic focusing of ESWT at the calcific deposit for treatment of calcifying tendinopathy is highly effective. Ultrasound is a simple, inexpensive and radiation-free diagnostic tool that has been used to demonstrate tendinopathy including calcific tendinitis. However, focusing of shock wave under ultrasound is less well established. We present a patient in whom large calcific tendinitis of gluteus medius was completely resolved by exact focusing of ESWT by ultrasound with literature review.

• The Journal of the Acoustical Society of Korea
• /
• v.18 no.5
• /
• pp.68-77
• /
• 1999

The paper looked into the effects of the spectral properties (waveform) of the high intensity focused ultrasound on suppression of the ultrasonic cavitation. Three different types of ultrasound were considered in the study, which were sinusoidal (1 MHz, 5 MPa), frequency modulated (from 1 MHz to 6 MHz for 10 ㎲, 5 MPa), asymmetrically shocked (fundamental frequency 1 MHz, peak positive pressure 12 MPa, peak negative pressure -4 MPa). The temporal response of an air bubble in water initially 1 ㎛ in radius to each type of the ultrasound was predicted using Gilmore bubble dynamic model and Church's rectified gas diffusion equation. It was shown that the radially pulsating amplitude of the bubble was greatly reduced for the frequency modulated wave and was little decreased for the shock wave, compared to the case that the bubble was exposed to the sinusoidal wave. It is interesting that the bubble response to the frequency modulated wave remains similar when the frequency component of the modulated ultrasound is beyond the bubble resonant frequency 3 MHz. This implies that, although the ultrasound is modulated up to 3MHz rather than up to the present 6 MHz, it is likely to produce similar cavitation suppression effects. In practice, it means that a typical narrow band ultrasonic transducer can be taken to generate an appropriate frequency modulated ultrasound to reduce cavitation activity. The present study indicates that ultrasonic cavitation may be suppressed to some extent by a proper spectral modification of high intensity ultrasound.

• The Journal of the Acoustical Society of Korea
• /
• v.31 no.6
• /
• pp.399-409
• /
• 2012

In this paper we propose a method for measuring the shear modulus of an ultrasound soft tissue phantom using an acoustic radiation force. The proposed method quantitatively determines the shear modulus based on the rise time of a displacement induced by an acoustic radiation force at the focal point of a focused ultrasound beam. The shear wave speed and shear modulus obtained from the proposed method and a shear wave propagation method were compared to verify the validity of the proposed method. In the shear wave propagation method, the shear modulus is first computed by measuring the propagating speed of a shear wave induced in a phantom by a limited-diffraction transmit field, and then was compared to that obtained with the proposed method in an ultrasound data acquisition system calibrated based on the first computed shear modulus. The relative errors between the two methods were found to be 4% for shear wave speed and less than 9% for shear modulus, confirming the usefulness of the proposed method.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.26 no.3
• /
• pp.181-189
• /
• 2006

A 2D finite-element numerical simulation has been developed to investigate the generation of ultrasonic waves in a homogeneous isotropic elastic slab under a line-focused laser irradiation. Discussing the physical processes involved in the thermoelastic phenomena, we describe a model for the pulsed laser generation of ultrasound in a metal slab. Addressing an analytic method, on the basis of an integral transform technique, for obtaining the solutions of the elastodynamic equation, we outline a finite element method for a numerical simulation of an ultrasonic wave propagation. We present the numerical results for the displacements and the stresses generated by a line-focused laser pulse on the surface of a stainless steel slab.

• Clinical Pain
• /
• v.18 no.2
• /
• pp.138-141
• /
• 2019

Lateral epicondylopathy represents pain in the lateral (radial aspect) of the elbow caused by degeneration in the common extensor tendon. Calcium deposit frequently developes in lateral epicondylopathy, with the prevalence up to 46%. There are considerable debates on its treatment protocols for lateral epicondylopathy so far, likewise, the effective treatment method for calcific lateral epicondylopathy has not been established. We report here a case of chronic intractable calcific lateral epicondylopathy treated with ultrasound-guided barbotage and focused type extracorporeal shock wave therapy (ESWT). To our knowledge, this is the first report of calcific lateral epicondylopathy treated by ultrasound-guided barbotage combined with ESWT.

• The Journal of the Acoustical Society of Korea
• /
• v.31 no.3
• /
• pp.151-160
• /
• 2012

In medical ultrasound imaging, elasticity imaging helps to diagnose tumors such as cancer. This paper is concerned with the application of acoustic radiation force to soft tissue of interest to implement elasticity imaging. In order to reduce the data acquisition time, instead of relying on transmit focusing, a plane wave of burst type is transmitted to apply the acoustic radiation force simultaneously to an entire imaging region to be observed. A homogeneous phantom experiment confirms that increasing the transmit excitation duration instead of employing transmit focusing generates a high enough acoustic radiation force to obtain elasticity images. It is found, however, that a different displacement versus time characteristic is observed unlike the case of using a conventional focused acoustic radiation force. Experimental results obtained through the use of an ultrasound phantom and a bovine liver show that lesions can be correctly differentiated.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.20 no.10
• /
• pp.63-71
• /
• 2021

Using fossil fuels in existing industrial systems causes a variety of social problems. Recently, many studies have been conducted on bio-refineries, which aim to actively utilize biomass to reduce the use of fossil fuels and solve various social problems. Among them, research using microalgae as a third-generation biomass has attracted considerable attention. Microalgae use inorganic matter to produce organic matter, and cell destruction is necessary to extract useful organic materials from microalgae. The extracted organic materials are currently used in various industrial fields. Numerous cell-destruction methods exist. We have investigated cell disruption by sonication, especially its efficiency. Ultrasound is a sound wave with frequencies above 20 kHz, and destroys cells by sending high energy through a cavitation that occurs, according to the characteristics of the sound wave. The Dunaliella salina microalgae used in this study was cultured in a flat-type photobioreactor. Experiments were performed using a batch low-frequency processing device. Logistic model was applied to analyze the results of cell-destruction experiments using ultrasound. The proper conditions for the most efficient cell destruction were OD 1.4(microalgae concentration)), 54watt(output power) and 200mL(microalgae capacity).

• Polymer(Korea)
• /
• v.26 no.3
• /
• pp.353-359
• /
• 2002

High intensity ultrasound has been applied to a series of poly(ethylene oxide) (PEO)/water systems having different molecular weights of PEO. Major interest was focused on the effect of ultrasonic wane on the melt viscosity chemical structure and thermal properties of PEO. The expected role of ultrasound used in this study was to generate macroradicals of PEO chains by the formation and subsequent collapse of bubbles. It was found that the melt viscosity and chemical structure of PEO change significantly depending on the sonication time. For the prolonged sonication, PEO chains were significantly degraded and new end groups were formed by the interplay of various radical species. When the molecular weight of PEO was relatively higher, the crystallization rate was decreased and the intensity of the melting peak was reduced.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.27 no.3
• /
• pp.246-254
• /
• 2007

The scanning laser source (SLS) technique is a promising new laser ultrasonic tool for the detection of small surface-breaking defects. The SLS approach is based on monitoring the changes in laser-generated ultrasound as a laser source is scanned over a defect. Changes in amplitude and frequency content are observed for ultrasound generated by the laser over uniform and defective areas. The SLS technique uses a point or a short line-focused high-power laser beam which is swept across the test specimen surface and passes over surface-breaking or subsurface flaws. The ultrasonic signal that arrives at the Rayleigh wave speed is monitored as the SLS is scanned. It is found that the amplitude and frequency of the measured ultrasonic signal have specific variations when the laser source approaches, passes over and moves behind the defect. In this paper, the setup for SLS experiments with full B-scan capability is described and SLS signatures from small surface-breaking and subsurface flaws are discussed using a point or short line focused laser source.