• Journal of the Korean Geotechnical Society
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• v.19 no.1
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• pp.229-236
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• 2003

Ultrasonic propagation velocities of both the dilatational and shear waves through the weathered tuff soil sampled from the area tying between Ulanbator and Beijing were measured under temperature condition of near subzero by means of sing-around method. After comparing the results with obtained data on unfrozen water content, a linear relation between velocities and unfrozen water content was performed with high coefficient value. Experimental results of two kinds of rather uniform materials, namely, glass-beads and silica micro-beads, testified the similar linear relations. In addition, the change rate of dilatational wave velocities with the change of volumetric unfrozen water content was not dependent on soil type. Although a rational theory of the ultrasonic velocities dependence on the unfrozen water content is not yet proposed, the presented empirical relationships may suggest the appropriate evaluation to the effect of unfrozen water on dynamic characteristics of frozen soil.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.1 no.2
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• pp.94-111
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• 2008

Traditionally the diagnosis and treatment of the diseases of the knee is based on the findings of the x-rays and the MRI. The x-rays provide good information of the changes of the internal structure of the bone. However, there is a limitation in providing information of the soft tissue and the cartilage. The MRI is one of the most expensive diagnostic modalities and it can not give us a dynamic and real time information. The sonography has a role in diagnosis and treatment of the soft tissue disease and surface of the bone. It gives us a real time dynamic information and it is really cheap. In this article the sonographic findings of the normal and pathologic conditions of the knee joint are introduced in relation to the findings of the x-rays and the MRI.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.2 no.2
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• pp.107-112
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• 2009

Ultrasonographic examination for the rotator cuff disease is dynamic noninvasive study and the results is comparable to MRI on the behalf of recent development. It also can be used as a tool for guided injection and follow up study after rotator cuff repair. The development of equipment, learning curve and knowledge for the disease are the three most important factors for the critical role of the ultrasonography in the diagnosis and treatment of the rotator cuff disease.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.2 no.1
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• pp.27-36
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• 2009

Musculoskeletal sonography is rapidly developing due to the merits such as relatively low cost and possibility of dynamic study. Sonography can be helpful and easily introduced for the diagnosis of the foot and ankle disease. This review tried to clarify the cause and sonographic diagnosis of common foot and ankle diseases.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.1312-1314
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• 2013

본 연구에서는 조영증강 의료 초음파 영상에서 효과적인 병변 탐색을 위한 방법론을 고찰한다. 병변 영상을 포함하는 ROI 추출을 위하여 조영효과의 전이 형태에 대한 단계 분할 기법과 동적 프로젝션 데이터의 분석 기법을 제안한다. 프레임간 유사도 척도의 분석을 통하여 비정상 프레임을 제거한 후 조영제의 도달시간(AT: Arrival Time)과 확산구간을 추출하여 탐색 대상 데이터의 양을 감소시킨다. 대상구간에서 초음파 영상의 수평방향 및 수직방향 프로젝션 데이터에 대한 동적 특성을 분석함으로써 후보영역을 추출하며 마이크로 버블의 추출, 조영효과의 증가속도 및 비율 등의 요소를 고려하여 ROI 를 선별하고 그 형태를 재조정한다. 부수적으로, 대상영역에서의 각 픽셀정보에 대하여 명도변화곡선(TIC) 특성분석을 통하여 영상을 재구성하고 병변영상의 형태와 윤곽선을 추출하게 된다.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.1 no.2
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• pp.73-77
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• 2008

Purpose: The purpose of this study was to describe the method of dynamic sonographic measurements in the evaluation of the MCL injury of the knee joint while applying valgus and varus stress. Materials and Methods: Seven cases of MCL injury from January to April of 2008 was used for the study. For the evaluation of the medial instability, sonography was used immediately after injury, 6 weeks and 12 weeks after conservative treatment with limited motion brace. The length between the foot of the medial femoral epicondyle and the most proximal point of the tibial cortex was measured in 30 degrees flexion with valgus and varus stress of the knee joint. Results: The foot of the medial epicondyle and the starting point of the proximal tibial cortex underneath the round portion of the articular cartilage were always able to be seen on ultrasonography, even in varus and valgus stress with gravity in 30 degrees flexion of the knee joint. The results of measurements were always constant. Conclusion: Sonography can be used in evaluation of medial instability under the dynamic valgus and varus stress of the knee joint without further injury.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.6 no.1
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• pp.28-37
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• 2013

Ultrasound is a first line examination of the knee and useful diagnostic tool in assessing the various knee lesions. The advantages of ultrasound are that it is non-invasive, easily available at bed side, cheap, well accepted by patients, and that it has technical benefits including dynamic evaluation. Its limitations include reliability, which is largely operator dependent and its inability to evaluate deep structures. Technical guidelines of the ultrasound released by European Society of MusculoSkeletal Radiology (ESSR) and ultrasonographic findings of various knee lesions are described.

• Journal of the Korean Society of Radiology
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• v.82 no.4
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• pp.889-902
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• 2021

Purpose To assess the diagnostic performance of contrast-enhanced ultrasound (CEUS) for additional MR-detected enhancing lesions and to determine whether or not kinetic pattern results comparable to dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) of the breast can be obtained using the quantitative analysis of CEUS. Materials and Methods In this single-center prospective study, a total of 71 additional MR-detected breast lesions were included. CEUS examination was performed, and lesions were categorized according to the Breast Imaging-Reporting and Data System (BI-RADS). The sensitivity, specificity, and diagnostic accuracy of CEUS were calculated by comparing the BI-RADS category to the final pathology results. The degree of agreement between CEUS and DCE-MRI kinetic patterns was evaluated using weighted kappa. Results On CEUS, 46 lesions were assigned as BI-RADS category 4B, 4C, or 5, while 25 lesions category 3 or 4A. The diagnostic performance of CEUS for enhancing lesions on DCE-MRI was excellent, with 84.9% sensitivity, 94.4% specificity, and 97.8% positive predictive value. A total of 57/71 (80%) lesions had correlating kinetic patterns and showed good agreement (weighted kappa = 0.66) between CEUS and DCE-MRI. Benign lesions showed excellent agreement (weighted kappa = 0.84), and invasive ductal carcinoma (IDC) showed good agreement (weighted kappa = 0.69). Conclusion The diagnostic performance of CEUS for additional MR-detected breast lesions was excellent. Accurate kinetic pattern assessment, fairly comparable to DCE-MRI, can be obtained for benign and IDC lesions using CEUS.

• Proceedings of the Korean Magnestics Society Conference
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• 1991.05a
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• pp.13-14
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• 1991

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.40-43
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• 2011

최근, 레이저 초음파 영상화 기법은 구조물의 비접촉식 손상 진단을 위해 널리 연구되고 있다. 초음파 영상화 기법의 가장 큰 장점은 비접촉식으로 구조물의 손상을 진단할 수 있고, 가진 및 측정 지점을 자유로이 이동할 수 있다는 점이다. 따라서 이는 고온이나 동적상태의 구조물에 적용이 가능하며, 시간과 공간상의 충분한 데이터를 획득할 수 있으므로 역문제 (Inverse problem)를 해결할 필요 없이 완전한 초음파의 전파 형상을 얻을 수 있다. 지난 연구들에서는 충분한 가진력 혹은 측정 민감도를 확보하기 위해 가진 레이저와 부착형 센서의 조합이나 부착형 가진 트렌스듀서와 센싱 레이저의 조합으로 초음파 영상을 획득하고자 하였다. 하지만 이들 조합은 가진 혹은 측정 지점이 구조물에 부착되어 있어 완전한 비접촉식 기법을 구현하지 못하였다. 이를 극복하고자 레이저와 EMAT 센서 등의 조합이 시도되어 왔으나, 이 또한 EMAT 센서의 적용 거리에 따른 한계점을 지니고 있다. 본 연구에서는 가진 레이저 (Nd:Yag)의 스캐닝을 통해 다양한 가진 점에서 발생된 초음파가 탄성체 구조물을 통해 전파되고, 이를 센싱 레이저 (Laser Doppler Vibrometer)를 이용하여 측정함으로써 비접촉식 초음파 영상화를 구현하였다. 나아가, 정상파 필터(Standing-wave filter)를 이용하여 구현된 초음파 영상으로부터 손상 영향만 검출해 내는 기법을 개발했다. 개발된 기법은 복합재 시편의 층간박리 (Delamination) 진단을 통해 검증하였다.