• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.1
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• pp.40-45
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• 2008

Immersion ultrasonic testing (UT) was used to determine elastic moduli of solid materials instead of the widely-used contact UT method. Conventionally, immersion UT is only used for determining the longitudinal wave speed. However, in this research, transverse wave speed was measured through finding transverse wave echoes caused by mode-conversion at material's boundary. Also, even in the cases when wave speeds could not be determined due to unknown thickness, Poisson's ratio was able to be calculated from the ratio of longitudinal and transverse wave speeds. This technique was verified for several materials, and it was found that higher accuracy was obtained by immersion UT method for materials either with relatively high wave speed or with relatively small Poisson's ratio. This technique thus will be suitable fur ceramics or high strength materials.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1140-1141
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• 2017

Depth of SWASH(Small Waterplane Area Single Hull) vessel which is an input value of its control system is measured by ultrasonic sensor. Distance to the its center of gravity can be simply calculated through ultrasonic sensor attached to the front of the vessel from the known values. However, it is to be calibrated with respect to its position for the accurate depth because it has geometric relation between the measurement value of ultrasonic sensor and the depth. In this research, depth calibration method of SWASH vessel using its position and ultrasonic sensor is introduced.

• Proceedings of the Korean Society of Computer Information Conference
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• 2012.01a
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• pp.73-75
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• 2012

본 논문에서는 복부 초음파 영상에서 근육 영역의 명암 대비를 강조하기 위해서 Multiple 연산을 적용한 후, 명암 대비가 강조된 영상에서 수직 방향의 명암도가 200 이상인 픽셀들에 대해 퍼지 기법에 적용하여 이진화한다. 이진화된 영상에서 피부층과 외복사근 사이에 존재하는 피하지방을 추출하기 위해 Thick-Search 방법을 적용하여 피부층과 외복사근을 추출한 후, 피부층과 외복사근의 사이에 Up-Down Search 방법을 적용하여 피하지방층을 추출한다. 피하지방층이 추출된 영상에서 근막의 형태학적 정보를 이용하여 근막을 추출한다. 추출된 근막 사이에 대해 Up-Down Search 방법을 적용하여 근육의 후보 영역을 추출한 후, 근육의 형태학적 정보를 이용하여 최종적인 근육 층을 추출한다. 추출된 근육의 경계선을 Monotone Cubic Hermite 보간법을 이용하여 근육의 경계선을 보정한 후, 최소자승법을 이용하여 근육의 두께를 측정한다. 제안된 방법을 복부 초음파 영상에 적용하여 근막 및 근육 영역을 추출한 결과, 기존의 근육 추출 방법보다 정확하게 추출되었고, 근육의 두께 측정 결과도 전문의가 육안으로 측정한 결과와 근사한 것을 확인할 수 있었다.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.5
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• pp.391-399
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• 2005

Laser-generated ultrasonic inspection system is a non-contact scanning inspection device with high spatial resolution and wide bandwidth. The amplitude of laser-generated ultrasound is varied according to the energy of pulse laser and the surface conditions of an object where the CW measuring laser beam is pointing. In this paper, we correct the generating errors by measuring the energy of pulse laser beam and correct the measuring errors by extracting the gain information of laser interferometer at each time. h dynamic stabilizer is developed to stably scan on the surface of an object for an laser-generated ultrasonic inspection system. The developed system generates ultrasound after adaptively finding the maximum gain time of an laser interferometer and processes the signal in real time after digitization with high speed. In this paper, we describe hardware configuration and control algorithm to build a stable laser-generated ultrasonic inspection system. Also, we confirmed through experiments that the proposed correction method for the generating errors and measuring errors is effective to improve the performance of a system.

• Journal of the Korea Society of Computer and Information
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• v.16 no.2
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• pp.55-60
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• 2011

In this paper, we propose a new method for extracting muscles from lumbar images. The proposed method sets areas without distortions with field expert's assistance as areas of measuring interest and removing noises from initial ultrasonic videos. Then, the method emphasizes the brightness contrast with Ends-in search stretching algorithm and separate thoracic vertebra from subcutaneous fat area using morphological characteristics. 4-directions contour tracing algorithm is applied to extract the bottom of subcutaneous fat area. Extracting thoracic vertebra area requires noise removal and morphological characteristics as well among candidate areas obtained by controlling min-max brightness. The thickness of muscles is then defined as the length between subcutaneous fat area and extracted thoracic vertebra. The experiment which consists of 368 image analysis verifies that the proposed method is more effective in measuring the thickness of muscles than before.

• The Journal of the Acoustical Society of Korea
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• v.41 no.5
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• pp.557-563
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• 2022

The cortical bone thickness of the tibia is related to fracture risk and overall bone status. The present study aims to investigate the feasibility of two different ultrasonic methods for measuring the cortical bone thickness in bovine tibia in vitro. In the reflection technique, the tibial cortical thickness was determined from ultrasonic reflections from the periosteum and the endosteum producing specific peaks in the signal envelope. In the axial transmission technique, the tibial cortical thickness was determined from ultrasonic guided wave velocities measured along the axial direction of the tibia. The cortical bone thickness determined by using the reflection technique correlated significantly with that measured by using a caliper, with a Pearson's correlation coefficient of r = 0.97 (p < 0.0001). In contrast, the correlation coefficients for the axial transmission technique were r = 0.92 (p < 0.0001) for the first arriving signal method and r = 0.89 (p < 0.0001) for the slow guided wave method. Clinical feasibility should be demonstrated with an in vivo application to address the question whether the ultrasonic methods presented here could be useful as a screening tool for osteoporosis and potentially could be applied to other skeletal sites such as the femur and the radius.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.12
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• pp.6066-6071
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• 2013

This paper proposes a calibration method for a freehand 3-D ultrasound system in medical robotic research. The calibration block with six wires was designed to set the fixed target points. The positions of the ultrasound probe and calibration block were measured using an optical tracker. The relationship between the position of the ultrasound probe and the pixel coordinates in the images was derived using a calibration process. The scaling matrix was also calculated. The experimental results showed that the proposed method could find solutions using a simple least square method from one or multiple ultrasound images.

• Journal of IKEEE
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• v.25 no.4
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• pp.584-590
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• 2021

This paper proposes a removal method of signal interference between ultrasound sensors where ghost signals due to interference are excluded and correct signal is recognized in distance mensurement using ultrasound sensors. The proposed method detects and excludes ghost signals when previous measured distance is compared to current measured distance and the distance difference exceeds a threshold. The threshold is fixed in conventional methods, so ghost signals cannot be correctly excluded when ultrasound sensor or target object move rapidly. On the contrary, to improve accuracy, the threshold is not fixed in the proposed method, and the threshold is adpatively determined based on the relative velocity when ultrasound sensor or target object move. Experiments of distance measurement with ultrasound signal interference are carried out where multiple ultrasound sensors of same type are exploited with maximum interference, and the results show that the proposed method efficiently exclude ghost signals.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.1
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• pp.78-82
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• 2019

This paper addressed the spectrum of ultrasonic waves produced by arc and/or coronal discharge inside the switchboard. Portable ultrasound sensors are useful for detecting discharge phenomena, such as coronal means in electrical systems. However, a typical handheld ultrasound detector has a disadvantage of determining the type of problem by listening to the sound characteristics and predicting the results, as a result of the determination of whether a discharge is present. Therefore, a new method of analysis is required to distinguish ultrasonic characteristics. In this paper, we published an ultrasound analysis case study to visualize the sound of ultrasonic waves measured with ultrasonic sensors. From the results of the experiment, it was possible to detect coronal discharge and serial arc discharge without interference by the ultrasonic detection system.

• Journal of the Mineralogical Society of Korea
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• v.13 no.3
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• pp.138-146
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• 2000

Using the ultrasonic interferometry on the single crystal MgO-periclase, adiabatic bulk moduli were determined to be 163.2 GPa and 162.6 GPa from (100) and (110) lattice plane measurements, respectively. Density was measured on polycrystalline MgO by the X-ray diffraction technique. Results from this study were compared with the previously reported values. Further, the present results were converted to the isothermal bulk moduli and, then compared with the published data available including the energy dispersive X-ray diffraction result which was performed on the same single crystal MgO. The principle and techniques ultrasonic interferometry were introduced too.