• The Journal of the Acoustical Society of Korea
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• v.29 no.3E
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• pp.111-118
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• 2010

Three-dimensional ultrasound imaging is a new, exciting technology that allows physicians to use ultrasound to view pathology as a volume, thereby enhancing comprehension of patient anatomy. In this paper, a brief history of the 3-D ultrasound imaging is described in accordance with the development of transducer technology. Then, two representative types of 3-D imaging transducers are reviewed with description of the concept and operation principle of each type: mechanical transducer and matrix array transducer. The mechanical transducer is detailed into free-hand scanning and sequential scanning types. Advantages of each transducer over the other and the technical issues for further performance enhancement are also presented.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.1
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• pp.27-34
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• 2016

The type of ultrasound transducer used influences the quality of a reconstructed ultrasound image. This study analyzed the effect of transducer type on ultrasound computed tomography (UCT) image quality. The UCT was modeled in an ultrasound simulator by using a 5 cm anatomy model and a ring-shape 5 MHz 128 transducer array, which considered attenuation, refraction, and reflection. Speed-of-sound images were reconstructed by the Radon transform as the UCT image modality. Acoustic impedance images were also reconstructed by the delay-and-sum (DAS) method, which considered the speed of sound information. To determine the optimal combination of transducers in observation, point-source, flat, and focused transducers were tested in combination as trasmitters and receivers; UCT images were constructed from each combination. The combination of point-source/flat transducer as transmitting and receiving devices presented the best reconstructed image quality. In UCT implementation, the combination of a flat transducer for transmitting and a point transducer for receiving permitted acceptable image quality.

• Journal of radiological science and technology
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• v.43 no.5
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• pp.367-374
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• 2020

The purpose of this study is to understand the infection prevention system and infection management perception of Ultrasound diagnostic room in medical institutions by sonographer's in general practitioner, semi and general hospitals. As a research method, a statistical analysis was conducted by surveying a total of 20 items in four category to determine the infection perception of sonographer's according to gender, age, working institution, and working period. As a result of infection awareness, males were in the ultrasound gel management category, women were in the transducer management category, all age groups were in the transducer management system category, and the General Practitioner, semi and general hospitals. were in the transducer management system category, and general hospitals showed a high degree of infection awareness in the category of disinfection and sterilization, and in the category of transducer management in the entire working period. In the results of the analysis of the correlation between the sub-factors of the perception of infection control in the Ultrasound diagnostic room the degree of correlation between each category showed a middle degree correlation(r>0.5) and a significant difference by category(p<.01). In conclusion, the prevention of infection in the ultrasound diagnostic room, which sonographer's firms think, was found to be the most efficient ultrasound diagnostic room infection control to implement transducer and gel management in accordance with the principles of disinfection and sterilization.

• Journal of Korea Multimedia Society
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• v.25 no.8
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• pp.1038-1048
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• 2022

Ultrasound is one of the effective methods for skin treatment. The skin penetration depth of the ultrasound depends on the ultrasonic frequency, that is, when the ultrasonic frequency is high, the depth is shallow. We have developed a transducer which can generate effectively 3 different ultrasonic frequencies removing interference between 3 types of frequencies according to impedance matching technology. The generated powers of transducer are 40.67W at 3.MHz, 17.46W at 11.7 MHz, and 14.79W at 21.5 MHz. The signal interference between the three frequencies is designed so that they do not interfere with each other by separating the signals using the SPDT (Single Pole, Double Throw) switch. The developed hybrid ultrasound transducer can be applied in skin care or skin treatment and beauty therapy.

• Journal of Sensor Science and Technology
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• v.27 no.6
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• pp.374-379
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• 2018

The piezocomposite transducer is widely used because it is highly efficient in transforming electric energy into mechanical energy, and its frequency range is broader than that of other types of ultrasound transducers. A general piezocomposite transducer is composed of an acoustic lens, impedance matching layers, piezoelectric materials, and backing layers. When an input voltage is applied to a piezoelectric material as an active material, it generates sound waves while vibrating. At that time, an impedance matching layer helps the sound waves to propagate forward while reducing the impedance mismatch that may occur at the interface between the active material and its front material. The impedance mismatch has a negative effect on the signal of an ultrasound transducer; thus, it is important to design a matching layer to overcome the issue. In this study, an optimized feature of a matching layer with gradient properties is studied. An objective function is defined to minimize both the average and the deviation of the reflection coefficients that are functions of the frequencies. As a result, an improvement in the signal characteristics with respect to the sensitivity and bandwidth is reported.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.1
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• pp.80-87
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• 1998

In this study, a multi-element ultrasound transducer has been developed aiming at basic experiment of three-dimension endovascular ultrasound endscopy for clinical diagnos, and experimental results of two-dimensional object imaging in the water are presented by the ultrasound tranducer and neural network. Each ultrasound echo received by thirty-six angular transducer elements is inputed to the eural network, and then backpropagation is used as a learning algorithm. A three-layer artificial neural network is used for learning and imaging of targetw placed in front of the transducer. The object shape of imaging is restricted to rectangular shapes by considering experimental restraint conditions. As a result, rough visualization can be realized even for objects with unlearned shapes through the training by primitive patterns of a various sized rectangular targets.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.41-45
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• 2006

The fabrication process of fiber placement system of carbon fiber reinforced plastic (CFRP) requires real time process control and reliable inspection to ensure quality by preventing defects such as delamination and void. Therefore, novel non-contact inspection technique is required during the non-destructive evaluation in a fiber placement system. For the inspection of delamination in CFRP, various methods to receive laser-generated ultrasound were applied by using piezoelectric transducer, air-coupled transducer, wavelet transform and scanning laser ultrasonic technique. Laser-generated ultrasound was received with a conventional piezoelectric sensor in contacting manner. Then signal characteristics due to defects were analyzed to find a factor for detecting defects. Air-coupled transducer was used for reception of laser-generated guided wave using linear slit array in order to generate high frequency guided wave. And line scan technique was used to confirm the capability of on-line application. The high frequency component of laser-generated guided wave received with piezoelectric sensor disappeared after propagating through delamination region. Nevertheless, it was failed to receive high frequency guided wave in using air-coupled transducer. The first peak of the frequency spectrum under 100kHz in the delamination region is higher than in the sound region. By using this feature, the line scanned frequency data were acquired in fully non-contact generation and reception of ultrasound. This method was proved as useful technique for detecting delamination in CFRP.

• The Journal of Information Technology
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• v.8 no.1
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• pp.43-50
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• 2005

Quantitative analysis for distribution of penetrating ultrasound in vivo is very important to determine the treatment region and method. In this paper, we constructed a simplified 2-D femoral region model that consists of skin-fat-muscle-bone layered system, and simulated the pressure distribution in the model in case of applying ultrasound using Finite Element Method(FEM). The ultrasound used in the simulation was assumed to be pulse wave and the pressure distribution was analyzed during only one period of pulse wave. In order to find the penetration depth, amplitude of pressure and sphere that ultrasound reaches in the model, we performed the simulation with varying the applied frequency, transducer size and amplitude of transducer's output. The result showed that applied frequency is inversely proportional to the penetration depth and amplitude of pressure but the amplitude of transducer's output is proportional to the amplitude of pressure in the model. Also, the sphere that ultrasound reaches was widened and the amplitude of pressure became larger as the transducer size became larger. This results were similar to that obtained from the previous model consisting of fat-muscle-bone layered system, but we observed that the pressure of ultrasound is decreased due to the decrements of pressure by the absorption coefficient of skin and the interference that depends on the reflection of ultrasound caused by the difference of acoustic impedance of skin and fat. Finally, we can infer that the model proposed in this study is closer to the realistic model than the previous ones. It shows that the results obtained from this study can be useful in designing the ultrasound treatment instrument or in setting up the treatment plan.

• Korean Journal of Optics and Photonics
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• v.28 no.4
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• pp.158-165
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• 2017

The physical shape of an ultrasound transducer has not been considered in previous studies of the photoacoustic saturation effect, where a photoacoustic signal's magnitude linearly increases as an absorption coefficient increases and it is finally saturated. In this paper, the effect of a spherically focused ultrasound transducer on photoacoustic nonlinearity is investigated. The focused ultrasound transducer's spatial filtering effect on photoacoustic signals is analytically derived considering the combined concept of a virtual point detector and Green function approach. The ultrasound transducer's temporal response (i.e., transfer function) effect on photoacoustic signals is considered by integrating photoacoustic signal values within the absorption area covered by a spatial resolution of the ultrasound transducer. Results from the analytically derived expression show that the magnitude of photoacoustic signals measured by a spherical focused ultrasound transducer shows a maximum at a specific absorption coefficient, and decreases after that maximum point as an absorption coefficient is increased. The origin of this photoacoustic nonlinearity is physically understood by comparing the ultrasound transducer's transfer functions and photoacoustic resonance spectra. In addition, this physical interpretation implies that the photoacoustic nonlinearity is strongly dependent on the irradiance distribution inside an absorption medium.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.6
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• pp.441-446
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• 2014

A 3D ultrasound image is desired in many medical examinations. However, the implementation of a 2D array, which is needed for a 3D image, is challenging with respect to fabrication, interconnection and cabling. A 2D sparse array, which needs fewer elements than a dense array, is a realistic way to achieve 3D images. Because the number of ways the elements can be placed in an array is extremely large, a method for optimizing the array configuration is needed. Previous research placed the target point far from the transducer array, making it impossible to optimize the array in the operating range. In our study, we focused on optimizing a 2D sparse array transducer for 3D imaging by using a simulated annealing method. We compared the far-field optimization method with the near-field optimization method by analyzing a point-spread function (PSF). The resolution of the optimized sparse array is comparable to that of the dense array.