• Corrosion Science and Technology
• /
• 제4권3호
• /
• pp.114-119
• /
• 2005

Since the degradation caused by corrosion is restricted to the surface of materials, conventional ultrasonic nondestructive evaluation methods based on ultrasonic bulk waves are not applicable to characterization of the corrosion degradation. To take care of this difficulty, a new nondestructive evaluation method that uses ultrasonic backward radiation has been proposed recently. This paper explores the potential of this newly developed method for nondestructive characterization and in-situ monitoring of corrosion degradation. Specifically, backward radiated ultrasounds from aged thermo-mechanically controlled process (TMCP) steel specimens by corrosion fatigue were measured and their characteristics were correlated to those of the aged specimens. The excellent correlation observed in the present study demonstrates the high potential of the backward radiated ultrasound as an effective tool for nondestructive characterization of corrosion degradation. In addition, the potential of the backward radiated ultrasound to in-situ monitoring of corrosion degradation is under current investigation.

• 대한의용생체공학회:의공학회지
• /
• 제27권1호
• /
• pp.22-29
• /
• 2006

This paper proposes an efficient array beamforming method using spatial matched filtering for ultrasound imaging. In the proposed method, ultrasound waves are transmitted from an array subaperture with fixed transmit focus as in conventional array imaging. At receive, radio frequency (RF) echo signals from each receive channel are passed through a spatial matched filter that is constructed based on the system transmit-receive spatial impulse response. The filtered echo signals are then summed. The filter remaps and spatially registers the acoustic energy from each element so that the pulse-echo impulse response of the summed output is focused with acceptably low side lobes. Analytical beam pattern analysis and simulation results using a linear array show that the proposed spatial filtering method can provide more improved spatial resolution and contrast-to-noise ratio (CNR) compared with conventional dynamic receive focusing (DRF) method by implementing two-way dynamically focused beam pattern throughout the field.

• 한국음향학회지
• /
• 제33권3호
• /
• pp.200-209
• /
• 2014

본 논문에서는 평면파 합성 송신집속 방법의 모델을 제시하고 수학적 해석을 통해 그 특성을 분석하였으며 일반적인 구형파 기반의 집속 방법과 비교하였다. 이를 통하여 평면파를 이용한 합성 송신집속 방법은 거리에 따라 주엽의 폭이 변하지 않는 비회절 빔을 발생함을 확인하였다. 또한 그레이팅 로브의 발생을 억제하며 원하는 주엽 폭을 얻기 위한 평면파 합성 방법, 그리고 비회절 특성이 유지되는 영역을 효과적으로 확장시킬 수 있는 방법을 제시하였다. 제안된 방법과 해석결과들을 컴퓨터 모의실험을 통해 검증하였다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2003년도 봄 학술발표회 논문집
• /
• pp.647-654
• /
• 2003

This study investigated the effect of ultrasound on the permeability of the filter paper The investigation involves laboratory experiments, and the laboratory tests were conducted under abroad range of conditions Including energy levels of ultrasonic waves, time for treatment, and temperature. The results of the study show that sonication enhances the permeability of the filter paper significantly. The degree of enhancement varies with sonication power and duration of application. The effect of sonication on permeability with temperature variation and concentration of the test specimens seems not to be significant.

• 대한의용생체공학회:의공학회지
• /
• 제7권1호
• /
• pp.41-44
• /
• 1986

The objective of tissue characterization is to provide quantitative information about the physical state of tissue interrogated by an ultrasound beam. In the computer simulation, it was found that the echoes were composed of the interferences of the ultrasonic waves reflected from both sides of the thin object, and could be separated by the spectral correlation method. Also, the phantom study demonstrates that thickness of the thin acryl layer beyond the resolution of common ultrasonic imaging systems can be measured- using this method.

• 대한정형외과 초음파학회지
• /
• 제5권2호
• /
• pp.94-98
• /
• 2012

석회화 건염은 건-골 부착부에 침착된 칼슘 수산화 인회석 결정 주위로 염증이 생기는 질환인데 체외충격파치료가 석회화 건염에 대한 비침습적 치료로써 효과적으로 많이 사용되고 있다. 실제 임상에서는 병변 부위에 정확히 체외충격파를 시행하기보다는 주로 촉진과 압통 부위 확인만으로 충격파 시행범위를 정하고 있다. 방사선 투시하에 석회 침착부위에 정확히 체외충격파를 시행하는 것이 임상 결과가 월등히 우수하다는 것은 알려져 있다. 초음파는 간편하고 비싸지 않으며 방사선 피폭이 없으면서 건 질환을 진단하는데 아주 효과적인 진단 기기이지만 체외충격파 치료의 조준에 있어서의 역할은 확립되어 있지 않다. 저자들은 중둔건에 발생한 거대 석회화 건염을 초음파를 이용하여 병변 부위의 위치를 정확히 조준하면서 체외충격파치료를 시행함으로써 석회 침착의 완전 소실을 얻은 증례를 경험하였기에 문헌 고찰과 함께 보고하고자 한다.

• 대한의용생체공학회:의공학회지
• /
• 제43권6호
• /
• pp.390-398
• /
• 2022

Ultrasound examination using ultrasound equipment is an ultrasound device that images human organs using sound waves and is used in various areas such as diagnosis, follow-up, and treatment of diseases. However, if the quality of ultrasound equipment is not guaranteed, the possibility of misdiagnosis increases, and the diagnosis rate decreases. Accordingly, The Korean Society of Radiology and Korea society of Ultrasound in Medicine presented guidelines for quality management of ultrasound equipment using ATS-539 phantom. The DenseNet201 classification algorithm shows 99.25% accuracy and 5.17% loss in the Dead Zone, 97.52% loss in Axial/Lateral Resolution, 96.98% accuracy and 20.64% loss in Sensitivity, 93.44% accuracy and 22.07% loss in the Gray scale and Dynamic Range. As a result, it is the best and is judged to be an algorithm that can be used for quantitative evaluation. Through this study, it can be seen that if quantitative evaluation using artificial intelligence is conducted in the qualitative evaluation item of ultrasonic equipment, the reliability of ultrasonic equipment can be increased with high accuracy.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
• /
• pp.273-275
• /
• 2005

Active thermography is being used since several years for remote non-destructive testing. It provides thermal images for remote detection and imaging of damages. Also, it is based on propagation and reflection of thermal waves which are launched from the surface into the inspected component by absorption of modulated radiation. For energy deposition, it use external heat sources (e.g., halogen lamp or convective heating) or internal heat generation (e.g., microwaves, eddy current, or elastic wave). Among the external heat sources, the ultrasound is generally used for energy deposition because of defect selective heating up. The heat source generating a thermal wave is provided by the defect itself due to the attenuation of amplitude modulated ultrasound. A defect causes locally enhanced losses and consequently selective heating up. Therefore amplitude modulation of the injected ultrasonic wave turns a defect into a thermal wave transmitter whose signal is detected at the surface by thermal infrared camera. This way ultrasound thermography(UT) allows for selective defect detection which enhances the probability of defect detection in the presence of complicated intact structures. In this paper the applicability of UT for fast defect detection is described. Examples are presented showing the detection of defects in PCB material. Measurements were performed on various kinds of typical defects in PCB materials (both Cu metal and non-metal epoxy). The obtained thermal image reveals area of defect in row of thick epoxy material and PCB.

• The Journal of Korean Physical Therapy
• /
• 제13권3호
• /
• pp.719-726
• /
• 2001

Transdermal drug delivery offers various advantages over conventional drug delivery systems, such as avoidance gastrointestinal degradation and hepatic first-pass effect. encourages patient compliance. and possible sustained release of drugs. However, transdermal transport of drugs is low permeability of the stratum corneum, the superficial layer of the skin. Many physicochemical and biological factors influencing transdermal transport is described together with the corresponding experimental and clinical results. Phonophoresis is medical treatment with drugs introduced into the skin by ultrasound energy. Enhanced drug penetration is through to result from the biophysical alterations of skin structure by ultrasound waves. The frequency used for phonophoresis is usually from 20 kHz to 15MHz. Phonophoresis can be categorized in to three ranges: low-frequency range(below 1 MHz). therapeutic frequency range(1 to 3MHz), and high-frequency range(above 3 MHz). The depth of penetration of ultrasound into skin is inversely proportional to the frequency. Cavitation may cause mechanical stress. temperature elevation, or enhanced chemical reactivity causing drug transport. One theory is that ultrasound affects the permeation of the stratum corneum lipid structure as the limiting step in permeating through the skin. The range of indications for phonophoresis is wide. Aspecific classification of the range of indications is obtained by classification of pathological conditions. The continuous research is needed for many interesting issucs of phonophoretic transdermal delivory in new future.

• 대한임상전기생리학회지
• /
• 제1권2호
• /
• pp.31-38
• /
• 2003

This study was to compared the effectiveness of piroxicam gel phonophoresis with conventional ultrasound therapy in knee osteoarthritis. Eighteen patients with a means age of $55.7{\pm}5$ years were randomly assigned to phonophoresis or ultrasound groups. Continuous ultrasonic waves of 1 MHz frequency and $1\;W/cm^2\;SATA_i$ were applied for 5 minutes to the target knee joint. This study indicated their pain level by marking on a visual analog scale(VAS) at the start of treatment and at the end of 3day. Osteoarthritis VAS scores, pain on rest state, non weight bearing range of motion, 20 meters walking, and walking step by the patients were evaluated before and after therapy. Both therapeutic modalities were found to be effective and generally well tolerated after 3 therapy sessions. But piroxicam phonophoresis was not superior to conventional ultrasound in patients with knee osteoarthritis.