• 대한의용생체공학회:의공학회지
• /
• 제19권2호
• /
• pp.171-176
• /
• 1998

본 연구에서는 뼈의 특성을 파악하는 초음파감쇠 파라미터를 재평가하였다. 초음파 속도, 특정 주파수(0.5MHz)에서의 초음파감쇠 및 광역 밴드 초음파감쇠와 같은 초음파 파라미터들을 해면골 입방체 시편의 세 직교방향(전/후, 내/외, 상/하)에서 측정하였다. 그리고 컴퓨터 영상장치를 사용하여 골밀도를 측정했으며, 골 시편의 무게와 부피를 이용하여 외형밀도도 함께얻었다. 이와같이 구해진 외형밀도와 초음파 속도로부터 초음파 탄성영률을 계산하였다. 주파수 0.5MHz에서의 초음파감쇠와 광역밴드감쇠는 골밀도 및 세 직교방향의 초음파 영률과 서로 관련시켜 연관성을 조사하였다. 그 결과 특정 주파수 초음파감쇠가 골밀도 및 탄성영률을 평가하는 능력에 있어서 광역밴드 감쇠보다 우수함을 알 수 있었다. 따라서 광역밴드 초음파감쇠를 측정하여 골의 상태를 평가하는 형행 초음파 진단 기법이 재검토 되어야 하며 본 연구에서 증명된 특정주파수(0.5MHz) 초음파감쇠를 이용하여 골 다공증 진단 예측율을 향상시킬 수 있다.

• 비파괴검사학회지
• /
• 제25권3호
• /
• pp.215-221
• /
• 2005

It is required to evaluate nondestructively depth of surface-breaking cracks in structures. In this paper, the self-compensated technique by laser-based ultrasound is used to measure the depth of surface-breaking defect. Optical generation of ultrasound produces a well defined pulse with reliable frequency content. It is broad banded and suitable for measurement of attenuation and scattering over a wide frequency range. The self-calibrated signal transmission data of surface wave shows good sensitivity as a practical tool far assessment of surface-breaking defect depth. It is suggested that the relationship between the signal transmission and crack depth can be used to predict the surface-breaking crack depths in structures.

• 대한기계학회논문집A
• /
• 제26권4호
• /
• pp.745-753
• /
• 2002

It is required to evaluate nondestructively the crack depth of surface-breaking cracks for the assurance of safety of structure. Optical generation of ultrasound produces well defined pulses with a repeatable frequency content, that are free of any mechanical resonances; they are broad band and are ideal for the measurement of attenuation and scattering over a wide frequency range. Self-calibrating surface signal transmission measurement is very sensitive and practical tool for surface-breaking crack depth. In this paper, the self-calibrating technique by laser-based ultrasound is used to evaluate the depth of surface-breaking crack of material. It is suggested that the relationship between the signal transmission and crack depth can be used as a practical model for predicting the surface-breaking crack depths from the signal transmission measured in structure.

• 한국음향학회:학술대회논문집
• /
• 한국음향학회 2002년도 하계학술발표대회 논문집 제21권 1호
• /
• pp.373-376
• /
• 2002

Most previous studies using ultrasound for osteoporosis diagnosis have employed ultrasound in a frequency range of 0.2-1 MHz. In this study, acoustic properties of the 12 defatted bovine cancellous bone specimens were investigated in vitro. Speed of sound (SOS) and broadband ultrasonic attenuation (BUA) were measured using three matched pairs of transducers with the center frequencies of 1, 2.25, and 3.5 MHz, respectively, in order to cover a broad frequency range of 0.5-2 MHz. The relative orientation between ultrasonic beam and bone specimens was the mediolateral (ML) direction of the bovine tibia. SOS showed significant linear positive correlations with apparent density for all three pairs of transducers of 1 MHz, 2.25 MHz, and 3.5 MHz, respectively. BUA showed relatively weak correlations with apparent density for the pairs of transducers of 1 MHz and 2.25 MHz. Furthermore, in the measurement with the pair of 3.5 MHz transducers, BUA was independent of apparent density. SOS and BUA were only weakly correlated with each other. The linear combination of SOS and BUA showed significant correlations with apparent density. These results suggest that the frequency range up to 1.5 MHz may be also useful in the osteoporosis diagnosis.