• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.3
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• pp.215-220
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• 2015

As a nondestructive inspection technology currently in use, infrared thermography has gradually expanded its application range to industry. The method detects only defect areas by grafting ultrasound on a technique of detecting infrared energy emitted from all objects with absolute temperature of 0 K and converting this energy into thermography for inspection. Ultrasound infrared thermography has merits including the ability to inspect a wide area in a short time without contacting the target object. This study investigated the applicability of the technique for defect detection using variable ultrasound excitation inspection methods on samples of Terfenol-D, a magnetostrictive material with a tunable natural resonant frequency.

• Journal of Yeungnam Medical Science
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• v.18 no.2
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• pp.170-186
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• 2001

Musculoskeletal ultrasound (MSUS) has newly evolved by the mechanical improvement of the machine over past several years, becoming a part of imaging techniques for the evaluation of variable diseases in the musculoskeletal system. MSUS has proven diagnostic superiority in pathologies including rotator cuff disease of the shoulder, lateral epicondylitis of the elbow, diseases of the peripheral nerve, detection of intra-articular loose bodies and soft tissue foreign bodies, and in evaluating small superficial soft tissue tumors such as ganglion, epidermoid cyst, and glomus tumor. Besides, MSUS is very useful for obtaining tissue or fluid via percutaneous fine needle aspiration and/or biopsy for the histopathologic diagnosis. Combining MSUS with MR would play a great role in the field of the diagnostic imaging of the musculoskeletal system. The MSUS examiner should have the knowledge of cross-sectional anatomy, and of the mechanical and physical properties of ultrasound in order to interpret the ultrasound findings accurately and properly, and to avoid diagnostic errors due to variable artifacts subsequently. The goal of this article is to introduce the capabilities of MSUS in certain kinds of clinical situation and to familiarize the reader with MSUS. For the purpose, author intends to describe this article according not to the disease-, or organ-based, but to the clinical problem-based format.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.5
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• pp.579-587
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• 2014

This paper presents a variable gain amplifier (VGA) for an analog front-end (AFE) of ultrasound medical imaging. This VGA has a closed-loop topology and shows a 37-dB-linear characteristic with a single-stage amplifier. It consists of an op-amp, a non-binary-weighted capacitor array, and a gain-control block. This non-binary-weighted capacitor array reduces the required number of capacitors and the complexity of the gain-control block. The VGA has been fabricated in a 0.35-mm CMOS process. This work gives the largest gain range of 37 dB per stage, the largest P1 dB of 9.5 dBm at the 3.3-V among the recent VGA circuits available in the literature. The voltage gain is controlled in the range of [-10, 27] dB in a linear-in-dB scale with 16 steps by a 4-bit digital code. The VGA has a bandpass characteristic with a passband of [20 kHz, 8 MHz].

• The Journal of the Acoustical Society of Korea
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• v.36 no.4
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• pp.238-246
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• 2017

High frequency ultrasound imaging typically suffers from low sensitivity due to the small aperture of high frequency transducers and shallow imaging depth due to the frequency-dependent attenuation of ultrasound. These limitations should be overcome to obtain high-frequency, high- resolution ultrasound images. One practical solution to the problems is a high-performance signal receiver capable of detecting a very small signal and amplifying the signal with minimal electronic noise addition. This paper reports a recently developed low-noise, wideband ultrasound receiver for high-frequency, high-resolution ultrasound imaging. The developed receiver has an amplification gain of up to 73 dB and a variable amplification gain range of 48 dB over an operating frequency of 80 MHz. Also, it has an amplification gain flatness of ${\pm}1dB$. Due to these high performances, the developed receiver has a signal-to-noise ratio of at least 8.4 dB and a contrast-to-noise ratio of at least 3.7 dB higher than commercial receivers.

• Preventive Nutrition and Food Science
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• v.14 no.2
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• pp.129-133
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• 2009

Salicornia herbacea is rich in natural minerals, dietary fibers, and potentially health-promoting phenolic compounds. In this paper, an experimental design was applied for the optimization of the ultrasound-assisted extraction of phenolic compounds from lyophilized Salicornia herbacea powder. The experiments were conducted in accordance with a five-level, three-variable central composite rotatable design (CCRD), and the effects of solvent concentration, extraction time, and extraction temperature were evaluated via response surface methodology (RSM). The optimal extraction conditions were as follows: ethanol concentration, 76.80%; extraction time, 20 min; and extraction temperature, $33.21^{\circ}C$; and the solvent concentration was the most significant parameter in this process, under which the predicted total phenolic content was 49.91 mg GAE/g sample.

• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.2
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• pp.390-396
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• 2008

Osteoarthritis(OA) diseases are characterized by joint pain, tenderness, limitation of movement, crepitus, occasional effusion, and variable degrees of inflammation without systemic effects. We investigated the effects of Achyrantis radixs cream treatment and low intensity ultrasound in monosodium iodoacetate(MIA) induced experimental osteoarthritis rat. Sprague-Dawley 40 rats of 7-8 weeks, weight $250\;{\pm}\;50$ g were divided into four groups including the control group and ostoarthritis group(30 rats). Histopathological examination, Mankin's score, and immunohistochemical were performed. Histological findings in control group that are similar to those observed in human osteoarthritis, such as disorganization of chondrocytes, erosion and fibrillation of cartilage surface, and subchondral bone exposure. Safranin O-fast green staining revealed that marked diffuse reduction of proteoglycans and chondrocyte treated with MIA. The Mankin's score were closely correlated to the grade of histological findings. The level of Bax and caspase-3 expression decreased experimental groups. This study shows that a Acyranthes Radix cream treatment and low intensity ultrasound exerts a beneficial influence on the severity of chondral lesion in osteoarthritis rats. This treatments could related to a reduced level of chondrocyte apoptosis through anti-apoptotoc capacities of MIA-induced apoptotic protein overexpression.

• Korean Journal of Materials Research
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• v.20 no.8
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• pp.439-443
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• 2010

Nano sized SiC particles (270 nm) are easily agglomerated in nickel sulfamate electrolytic bath during a composite electrodeposition process. The agglomeration of nano particles in composite coatings can significantly reduce the mechanical properties of the composite coatings. In this study, Ni-SiC nano composite coatings were fabricated using a conventional electrodeposition process with the aid of ultrasound. Nano particles were found to be distributed homogeneously with reduced agglomeration in the ultrasonicated samples. Substantial improvements in mechanical properties were observed in the composite coatings prepared in presence of ultrasound over those without ultrasound. Ni-SiC composite coatings were prepared with variable ultrasonic frequencies ranging from 24 kHz to 78 kHz and ultrasonic powers up to 300 watts. The ultrasonic frequency of 38 kHz with ultrasonic power of 200 watt was revealed to be the best ultrasonic conditions for homogeneous dispersion of nano SiC particles with improved mechanical properties in the composite coatings. The microstructures, phase compositions, and mechanical properties of the composite coatings were observed and evaluated using SEM, XRD, Vickers microhardness, and wear test. The Vickers microhardness of composite coatings under ultrasonic condition was significantly improved as compared to the coatings without ultrasound. The friction coefficient of the composite coating prepared with an ultrasonic condition was also smaller than the pure nickel coatings. A synergistic combination of superior wear resistance and improved microhardness was found in the Ni-SiC composite coatings prepared with ultrasonic conditions.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.5
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• pp.502-508
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• 2012

Quantitative ultrasound technologies for osteoporosis diagnosis measure ultrasonic parameters such as speed of sound(SOS) and normalized broadband ultrasound attenuation(nBUA) in the calcaneus (heel bone). In the present study, the dependences of SOS and nBUA on bone mineral density in the proximal femur with high risk of fracture were investigated by using 20 trabecular bone samples extracted from bovine femurs. SOS and nBUA in the femoral trabecular bone samples were measured by using a transverse transmission method with one matched pair of ultrasonic transducers with a center frequency of 1.0 MHz. SOS and nBUA measured in the 20 trabecular bone samples exhibited high Pearson's correlation coefficients (r) of r = 0.83 and 0.72 with apparent bone density, respectively. The multiple regression analysis with SOS and nBUA as independent variables and apparent bone density as a dependent variable showed that the correlation coefficient r = 0.85 of the multiple linear regression model was higher than those of the simple linear regression model with either parameter SOS or nBUA as an independent variable. These high linear correlations between the ultrasonic parameters and the bone density suggest that the ultrasonic parameters measured in the femur can be useful for predicting the femoral bone mineral density.

• Journal of the Korean Society of Radiology
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• v.84 no.6
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• pp.1233-1243
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• 2023

Percutaneous ultrasound-guided biopsy is useful for the pathologic confirmation of variable body lesions to establish diagnostic and therapeutic approaches. However, deep pelvic lesions are a challenge for pathologic diagnoses because of the presence of the bowel, bladder, major vessels, and pelvic bones which make a percutaneous approach difficult and dangerous. In female, the vagina is elastic and near the pelvic internal organs. Therefore, transvaginal ultrasound may serve as an effective and safe guide for the pathologic diagnosis of pelvis lesions. This review aimed to introduce the indications for, and the method of transvaginal ultrasoundguided biopsy, and to describe the reported diagnostic accuracy and safety.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.10 s.241
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• pp.1430-1437
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• 2005

It is very important to achieve a high reproducibility in the ultrasonic measurement of bone mineral density. In this study, we examined number of sampling waveform, control of temperature, diameter of region of interest as factors to improve reproducibility. We decided the optimal number of waveforms to be converted to frequency domain as period of 1. We have minimized the effects of variable temperature and constrained generation of micro bubble by keeping temperature within a range of $32\pm0.5^{\circ}C$ with a precise temperature controlling algorithm. We also found the optimal diameter of region of interest to be 13mm. In this paper, we demonstrated the improved reproducibility by controlling various factors affecting the ultrasonic measurement of bone mineral density.