• Asian Pacific Journal of Cancer Prevention
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• v.16 no.16
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• pp.7291-7294
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• 2015

Purpsoe: To investigate the diagnostic value of quantitative analysis of a tissue diffusion and virtual touch tissue imaging quantification (VTIQ) technique with acoustic radiation force impulse (ARFI) elastography for assessing enlarged cervical lymph nodes. Materials and Methods: Fifty-six enlarged cervical lymph nodes confirmed by pathologic diagnoses were covered in the study. According to the results of pathologic diagnosis, patients were classified into benign and malignant groups. All the patients were examined by both conventional ultrasonography and elastography. AREA% and shear wave velocity (SWV) in ROI of different groups were calculated and compared using ROC curves. Cut-off points of AREA% and SWV were determined with receiver operating characteristic curves. Results: Final histopathological results revealed 21 cases of benign and 35 cases of malignant lymph nodes. The mean values of AREA% and SWV in benign and malignant groups were $45.0{\pm}17.9%$ and $2.32{\pm}0.57m/s$, and $61.3{\pm}21.29%$ and $4.36{\pm}1.25$)m/s, respectively. For the parameters of elastography, "AREA%" and SWV demonstrated significant differences between groups (p=0.002). AREA% was positively correlated with SWV with a correlation coefficient of 0.809 (P<0.001). Conclusions: Stiffness of different lymph node diseases in patients may differ. Elastography can evaluate changes sensitively and provide valuable information to doctors. The study proved that the VTIQ elastography technique can play an important role in differential diagnosis of lymph nodes.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.5
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• pp.362-367
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• 2005

Ultrasonic backward radiation profile is frequency-dependent when the incident region has deptional gradient of acoustical properties or multi-layers. Until now, we have measured the profiles of principal frequencies of an used transducers so that it was not easy to characterize the frequency dependence of the SAW(surface acoustic wave) from the backward radiation profile. We tried to measure the spectral backward radiation profiles using DFP(digital filer package) in a Lecroy DSO(digital storage oscilloscope). The measured spectral profiles showed that the steel specimen of #1200 surface treatment have 2% SAW velocity dispersion of the loaded case and the severly rusty steel specimen have the very big changes in the shape and pattern of the spectral profile. It is concluded that the spectral backward radiation profiles could be very effective tool to evaluate the frequency dependence of surface area.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.7-15
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• 2017

The purpose of this study was to evaluate the properties of recycled aggregate concrete (RAC) using low quality recycled aggregate with or without washing before usage. The recycled aggregate concrete evaluated in this study contained various amounts of low quality recycled aggregate, viz. 30%, 60% and 100%. To evaluate the performance of the recycled aggregate concrete, various test methods were employed to assess its compressive strength, absorption, surface resistance, ultrasound velocity, chloride ion resistance, etc. The properties of the RAC with 30% and 60% washed recycled aggregate were similar those of the natural aggregate. However, the properties of the RAC with 100% washed recycled aggregate were slightly lower than those of the other versions. Also, the RAC with the non-washed recycled aggregate exhibited lower performance results. The results showed that the RAC with washed recycled aggregate had similar properties to normal concrete (concrete using natural aggregate). This implies that the recycled aggregate should be washed to improve the RCA.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.6
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• pp.190-197
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• 2014

In this paper, we present a method for optical parameter-based material rendering with measuring the thickness of a material using ultrasonic waves. Thickness is an important element in determining the reflectance and transmittance of a material along with its optical characteristics and plays a crucial role in more realistic object rendering. In studies conducted thus far, thickness has been measured and used for rendering. The proposed method is a novel method attempted for the first time ever to render a material considering the thickness of a material whose thickness cannot be measured by visual assessment, using ultrasonic waves. It was implemented by measuring the sound velocity of the reference sample and applying the results to the thickness measurement of other objects that have the same characteristics. The characteristics of the objects measured are reflected in the quality of the final rendering, thus verifying the importance of thickness in rendering.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.10
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• pp.123-130
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• 2007

Hypoplastic left heart syndrome is currently the most lethal cardiac malformation of the newborn infant. Survival following a Norwood operation depends on the balance between systemic and pulmonary blood flow, which is highly dependent on the fluid dynamics through the interposition shunt between the two circulations. The purpose of this study is an optimization of the systemic-to-pulmonary artery shunt. In this study, We used computational fluid dynamic(CFD) models to determine the velocity profile in a systemic-to-pulmonary artery shunt and suggested a simplified method of calculating the blood flow in the shunt based on Ultrasound systems. We analyzed the flow characteristic variations and oscillatory shear index(OSI) due to the anastomosis angle and shunt diameter changing. Four different CFD models were constructed with the shunt sizes ranging from 3 to 3.5mm. The angle between the brachiocephalic trunk(BCT) and the shunt were $30^{\circ}$ and $45^{\circ}$, respectively. When the diameter is 3.0 mm, the oscillatory shear index decreased by 1.2% at $30^{\circ}$ as opposed to at $45^{\circ}$. When the diameter is 3.5 mm, it increased by 18% more at $30^{\circ}$ as opposed to at $45^{\circ}$. When the joint angle is $30^{\circ}$ and the diameter is 3.0 mm, the oscillatory shear index decreased by 4.1% in comparison with the 3.5 mm diameter. When the angle is $45^{\circ}$ and the diameter is 3.0 mm, the index increased by 14.6% in comparison with the 3.5 mm diameter.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.2
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• pp.103-109
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• 2005

Fiber reinforced plastic material should be inspected in fabrication process in order to enhance quality by prevent defects such as delamination and void. Generally, ultrasonic technique is widely used to evaluate FRP. In conventional ultrasonic techniques, transducer should be contacted on FRP. However, conventional contacting method could not be applied in fabrication process and novel non-contact evaluating technique was required. Laser-based ultrasonic technique was tried to evaluate CFRP plate. Laser-based ultrasonic waves propagated on CFRP were received with various transducers such as accelerometer and AE sensor in order to evaluate the properties of waves due to the variation of frequency. Velocities of laser-based ultrasonic waves were evaluated for various fiber orientation. In addition, laser interferometry was used to receive ultrasonic wave in CFRP and frequency was analysed.

• The Journal of the Acoustical Society of Korea
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• v.40 no.4
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• pp.270-277
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• 2021

In the power ultrasound fields, the flange position for fixing the transducer is an important factor influencing on electro-mechanical efficiency of the transducer. We suggested a practical method that can determine the installation position of the flange for different resonance modes of the bolt-clamped type Langevin ultrasonic transducer. A semicircular wedge-shaped jig was manufactured and moved along the lateral surface of the transducer. The vibration characteristics were examined after a constant pressure was applied to the semicircular wedge-shaped jig. By observing the change of the input admittance of the transducer depending on the position of the pressure application, the optimum position for the flange installation could be determined. The resonant modes of the transducer were calculated by a Mason's equivalent circuit, and the particle velocity distribution for each resonance mode was calculated by a transmission line model. Since the optimum positions determined from an experimental result show a good correspondence with the node positions of the vibration modes calculated by the transmission line model, the validity of the suggested method was verified.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.07a
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• pp.19-22
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• 2019

상완동맥은 어깨에서부터 팔꿈치까지 내려오는 상완골의 내측부에 존재하며 혈압을 측정할 때 사용되는 혈관이다. 이 혈관은 골절로 인해 찢어지거나, 또는 혈액순환에 문제가 생겨 혈관이 막히는 경우가 발생한다. 이러한 경우 혈관의 상태를 확인하기 위하여 색조 도플러 초음파 검사를 사용하지만, 사용자에 따라 영상을 통한 판단 기준이 다르다는 문제점이 발생한다. 따라서 본 논문에서는 FCM과 Fuzzy Decision Tree를 이용한 영상 처리를 통해 일관성 있는 판단기준을 세우기 위한 혈류의 속도를 제안한다. 색조 도플러 초음파 영상에서의 상완 동맥을 추출하여 기울기를 이용한 FCM 알고리즘을 통해 소속도를 추출한 뒤 퍼지 룰에 적용하여 의사 결정 트리로 등급을 분류하고 결과적으로 혈류 속도를 추출한다. 색조 도플러 초음파 영상에서 환자의 개인 정보를 보호하기 위해 개인 정보 영역을 제거하여 ROI 영역을 추출하고 ROI 영역을 이진화를 통하여 상완동맥이 있는 영역을 추출한다. 이진화 된 ROI 영역에서 혈관 영상의 혈류 방향으로의 무게중심을 설정하고 각각의 픽셀과 무게중심 선과의 거리를 이용하여 소속도를 추출한 후 FCM을 사용하여 최적의 기울기를 선정한다. FCM을 통해 추출한 최종 소속도를 이용하여 퍼지 룰에 적용한 뒤 계산된 T-norm과 소속도의 분산을 이용하여 의사 결정 트리를 형성 트리의 단말 노드들은 각 픽셀을 분류한다. 분류되어진 데이터들의 노드별 소속도 평균을 구한 뒤 디퍼지화를 통해 COG(Center of Gravity)를 계산한다. 마지막으로 그 값을 이용하여 혈류 속도에 영향을 미치는 정도를 계산한 뒤 최종 혈류의 속도를 제안한다.

• Korean Journal of Clinical Laboratory Science
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• v.55 no.3
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• pp.219-226
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• 2023

Transcranial doppler ultrasonography (TCD) applies a low frequency of 2 MHz to measure the blood flow velocity and waveform within the skull. Medical technologists at several hospitals are conducting these examinations, and education is being imparted in many schools and academic societies. However, the skill of the tester is of utmost importance when performing TCD. Technicians who are conducting the procedure for the first time have trouble locating the blood vessels, and some experienced personnel are worried because too many blood vessels are present. Since this procedure does not directly look at and measure blood vessels, there are several limitations and difficulties. Therefore, this study aims to provide some help by introducing precautions and suggestions for TCD technicians conducting the test.

• Korean Journal of Radiology
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• v.21 no.7
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• pp.900-907
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• 2020

Objective: To investigate the predictive value of intraplaque neovascularization (IPN) for cardiovascular outcomes. Materials and Methods: We evaluated 217 patients with coronary artery disease (CAD) (158 men; mean age, 68 ± 10 years) with a maximal carotid plaque thickness ≥ 1.5 mm for the presence of IPN using contrast-enhanced ultrasonography. We compared patients with (n = 116) and without (n = 101) IPN during the follow-up period and investigated the predictors of major adverse cardiovascular events (MACE), including cardiac death, myocardial infarction, coronary artery revascularization, and transient ischemic accident/stroke. Results: During the mean follow-up period of 995 ± 610 days, the MACE rate was 6% (13/217). Patients with IPN had a higher maximal thickness than those without IPN (2.86 ± 1.01 vs. 2.61 ± 0.84 mm, p = 0.046). Common carotid artery-peak systolic velocity, left ventricular mass index (LVMI), and ventricular-vascular coupling index were significantly correlated with MACE. However, on multivariate Cox regression analysis, increased LVMI was independently related to MACE (p < 0.05). The presence of IPN could not predict MACE. Conclusion: The presence of IPN was related to a higher plaque thickness but could not predict cardiovascular outcomes better than conventional clinical factors in patients with CAD.