• 전기의세계
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• v.34 no.9
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• pp.541-547
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• 1985

생체내부의 영상진단법 중에 진단시 인체에 무해, 무통하며 실시간 동적 영상을 제공해주는 치명적인 잇점을 갖고 있는 초음파영상 진단장치는 그 내부를 살펴보면 타 의용장치와는 달리 전기.전자공학의 결정체이다. 그러나 X선 CT에 비해 화질이 멀어지고 정량성 결여의 문제점을 안고 있다. 그러나, 소형, 저렴성은 그 이용도를 높혀주고 있으나 화질불량은 화상진단시 숙련을 요구하고 확실한 정보 제공의 장벽이 되고 있다. 따라서 상기의 문제점을 해결하기 위한 노력의 일환이 Tissue Characteization이다.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.1 no.1
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• pp.14-17
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• 2008

Meniscal extrusion is defined as a distance of 3 mm or more between the peripheral border of the meniscus and the edge of the tibial plateau on the coronal plane, associated with degeneration or tear of meniscus, effusion, osteophyte, osteoarthritis. There are many advantages of ultrasonography, including cost, dynamic real-time assessment. We evaluated a patient with anteromedial mass of the knee by ultrasonography, which was proved to be the extrusion of medial meniscus. We report a case of extrusion of medial meniscus evaluated by ultrasonography with review of the related literatures.

• Journal of Energy Engineering
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• v.12 no.2
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• pp.139-144
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• 2003

Augmentation of CHF by ultrasonic vibration in water pool is experimentally investigated under pool boiling condition. The experiments are carried out using copper coated plates and distilled water. Measurements of CHF on flat plate heated surface were made with and without ultrasonic wave and with variations in inclined angle of the surface and water subcooling. Experimental apparatus consists of a bath, power supply, test section, ultrasonic generator, and data acquisition system. The measurements show that ultrasonic wave enhances CHF and its extent is dependent upon inclination angle as well as water subcooling. The rate of increase in CHF increases with an increase in water subcooling while it decreases with an increase in inclination angle. Visual observation shows that the cause of CHF augmentation is closely related with the dynamic behavior of bubble generation and departure in acoustic field.

• Journal of Korea Foresty Energy
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• v.25 no.2
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• pp.49-54
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• 2006

This study was carried out to provide basic data for using domestic structural softwood lumber efficiently and ensuring structural safety of timber structures. The ratios (k-factor) between static and dynamic MOE measured by ultrasonic device for $2{\times}6$ domestic softwood structural lumber are 1.0602 for Korean red pine, 1.0013 for Korean white pine and 1.2320 for Japanese larch. In machine grade using nondestructive method, 76% of Korean red pine was classified into higher than E9 grade, 85% of Korean white pine was sorted into higher than E7 grade and 68% of Japanese larch was classified into higher than E11 grade. Correlation between MOE and MOR by static bending with k-factor from nondestructive method provide a possibility to predict bending strength and allowable stress of domestic softwood structural lumber.

• Journal of the Korean Wood Science and Technology
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• v.42 no.3
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• pp.275-281
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• 2014

In this study, accelerated weathering test was performed with wood, a major material for wooden cultural building. In order to evaluate the deterioration of wood, ultrasonic transmission times were measured to evaluate dynamic modulus of elasticity (MOE), which was verified by determining static MOE using three-point bending test. Ultrasonic transmission time was decreased with an increase in the weathering time levels (0, 500, 1000 hours) while it increased in 1500 and 2000 hours. Distribution of dynamic and static MOE was similar to that of the ultrasonic transmission time measurements. The results mean that the measurement of ultrasonic transmission time was very effective to evaluate MOE of wooden cultural buildings for their preservation and management. This method could be utilized to assess wooden cultural buildings as a way of preserving them in a scientific manner.

• Journal of KIISE
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• v.42 no.7
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• pp.910-918
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• 2015

This paper presents a parameter visualization technique to overcome the limitation of the naked eye in contrast-enhanced ultrasonography. A method is also proposed to compensate for the distortion and noise in ultrasound image sequences. Meaningful parameters for diagnosing liver disease can be extracted from the dynamic patterns of the contrast enhancement in ultrasound images. The visualization technique can provide more accurate information by generating a parametric image from the dynamic data. Respiratory motions and noise from micro-bubble in ultrasound data may cause a degradation of the reliability of the diagnostic parameters. A multi-stage algorithm for respiratory motion tracking and an image enhancement technique based on the Markov Random Field are proposed. The usefulness of the proposed methods is empirically discussed through experiments by using a set of clinical data.

• The Journal of the Acoustical Society of Korea
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• v.35 no.2
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• pp.134-142
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• 2016

In this paper, a method synthesizing speech signal using the 40 kHz ultrasonic signals reflected from the articulatory muscles was introduced and performance was evaluated. When the ultrasound signals are radiated to articulating face, the Doppler effects caused by movements of lips, jaw, and chin observed. The signals that have different frequencies from that of the transmitted signals are found in the received signals. These ADS (Acoustic-Doppler Signals) were used for estimating of the speech parameters in this study. Prior to synthesizing speech signal, a quantitative correlation analysis between ADS and speech signals was carried out on each frequency bin. According to the results, the feasibility of the ADS-based speech synthesis was validated. ADS-to-speech transformation was achieved by the joint Gaussian mixture model-based conversion rules. The experimental results from the 5 subjects showed that filter bank energy and LPC (Linear Predictive Coefficient) cepstrum coefficients are the optimal features for ADS, and speech, respectively. In the subjective evaluation where synthesized speech signals were obtained using the excitation sources extracted from original speech signals, it was confirmed that the ADS-to-speech conversion method yielded 72.2 % average recognition rates.

• Journal of Sensor Science and Technology
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• v.2 no.1
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• pp.49-56
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• 1993

This paper describes an effort of improving performances of ultrasonic ranging system using V40 microprocessor. Conventional ranging systems are somewhat inaccurate because they do not have capability of compensating changes in medium condition. The novel ranging system overcomes this disadvantage by placing a dummy sensor functioning as a standard calibrating instrument in the same medium and by providing data processing capability using V40 controller. Also data communication between V40 and personal computer via RS232C makes it possible to use the ranging system for varieties of other applications such as analysis of static and dynamic system.

• Journal of the Korean Society of Radiology
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• v.2 no.2
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• pp.17-21
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• 2008

Image quality is improved if the high frequency domains of boundary surface are made distinct. We suggested a method of correcting indistinct defects in ultrasonic images resulting from dynamic imaging. According to the results of the experiment, boundaries in input ultrasonic images became distinct. However, we need to solve the problem that information on pixels of low signal intensity adjacent to boundaries is lost because high-frequency components in the boundaries are strong.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.708-711
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• 2016

본 논문에서는 의료초음파 영상에서 진단 파라미터 데이터를 가시화 하는 방법론으로서 연속적인 픽셀 값을 갖는 전이시간 데이터의 표현과, 4가지 유형의 값으로 분류되는 병변 진단 파라미터 영상을 생성하는 방법을 제시한다. 또한 생성된 파라미터 영상에서 노이즈를 제거하기 위한 방법론으로서 MRF 모델을 이용한 영상개선 기법을 제안한다. 이러한 파라미터 영상 생성기법은 초음파 진단 데이터에서 조영증강 패턴의 동적인 변화에 대한 육안 판별의 한계를 극복할 수 있게 한다. MRF 기반 영상개선 과정에서 연속적인 픽셀 값에 대한 에너지함수를 정의하고 이를 최적화 하는 기법을 개발하였으며 실제 의료영상을 사용한 실험을 통하여 제안된 이론의 유용성을 평가하였다.