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이시열,김선호,이동언,박춘수,김민우,SiYeoul Lee,Seonho Kim,Dongeon Lee,ChunSu Park,MinWoo Kim 대한의용생체공학회 2023 의공학회지 Vol.44 No.4
Clinical ultrasound (US) is a widely used imaging modality with various clinical applications. However, capturing a large field of view often requires specialized transducers which have limitations for specific clinical scenarios. Panoramic imaging offers an alternative approach by sequentially aligning image sections acquired from freehand sweeps using a standard transducer. To reconstruct a 3D volume from these 2D sections, an external device can be employed to track the transducer's motion accurately. However, the presence of optical or electrical interferences in a clinical setting often leads to incorrect measurements from such sensors. In this paper, we propose a deep learning (DL) framework that enables the prediction of scan trajectories using only US data, eliminating the need for an external tracking device. Our approach incorporates diverse data types, including correlation volume, optical flow, B-mode images, and rawer data (IQ data). We develop a DL network capable of effectively handling these data types and introduce an attention technique to emphasize crucial local areas for precise trajectory prediction. Through extensive experimentation, we demonstrate the superiority of our proposed method over other DL-based approaches in terms of long trajectory prediction performance. Our findings highlight the potential of employing DL techniques for trajectory estimation in clinical ultrasound, offering a promising alternative for panoramic imaging.
거친 지표면 조도구분의 패턴에 따른 난류경계층의 유동 및왜도에 미치는 영향에 대한 연구
박권호,이시열,임희창 한국풍공학회 2018 한국풍공학회지 Vol.22 No.3
In this study, the characteristics of flow field on the rough surface were examined. The fully developed thick turbulent boundary layer has been made in the boundary layer wind tunnel with the cube arrays patch on the floor of boundary layer wind tunnel, which has patterns of staggered and aligned roughness. The boundary layer properties such as mean flow and turbulent statistics such as stresses and skewness were measured using thermal anemometry. In order to compare with wind tunnel measurement, the turbulent boundary layer was also simulated using the numerical simulation. Rough wall surface was basically used generate the turbulent boundary layer and periodic boundary condition was coaxially applied for both inlet and outlet sections. Results show that turbulent boundary layer have successfully been generated on the roughness surface, and the boundary layer properties vary depending on the pattern of surface roughness. 본 연구는 거친 표면에서의 유동장 특성에 대해 실험 및 수치해석적 연구를 수행하였다. 완전 발달한 두꺼운 난류경계층은풍동 내 바닥에 깔린 거친 표면을 이용하여 생성하였다. 평균유동과 난류강도 및 왜도와 같은 난류경계층의 특성을 열선유속계를 이용해 측정하였다. 풍동실험결과와의 비교를 위해 난류경계층은 수치해석을 이용하여 모사하였다. 거친 벽표면은 기본적으로 난류경계층 생성에 사용되었으며 입출구면에는 주기경계조건이 적용되었다. 본 연구결과로서 난류경계층이 거친 표면 위에서 성공적으로 생성되었으며 평균유동과 난류강도 및 왜도와 같은 난류경계층의 특성은 지표면조도에 따라 달라진다는 것을 확인하였다.
부신피질 호르몬이 사람골수기질세포의 Apoptosis에 미치는 영향
김하영,김덕재,이시열,홍정수,김동관,김기수 대한내분비학회 2002 Endocrinology and metabolism Vol.17 No.1
Background: Osteoporosis is one of the most serious side effects of long-term glucocorticoid therapy, but the mechanism of glucocorticoid-induced bone loss remains poorly defined. Glucocorticoid induces decreased bone formation and death of isolated segments of bone (osteonecrosis) suggesting that glucocorticoid excess may affect the birth or death rate of bone cells and thereby reduce their numbers. It has been known that reduction in bone formation is due to reduced proliferation in osteoblast precursor cells and reduced matrix synthesis in mature osteoblast. Here, we present evidence for dexamethasone-induced apoptosis on human bone marrow stromal cells (hBMSC). To understand the mechanism of glucocorticoid-induced osteoporosis, we investigated the effects of glucocorticoid on primary cultured hBMSC. Methods: Treatment with dexamethasone at the concentration of 10^-9 M for 3∼5 days significantly decreased cleavage tetrazolium salt WST-1 level/concentration by mitochondrial dehydrogenase in viable cells. Greater decrease was observed with higher concentration of dexamethasone (10^-7 M, and 10^-5 M). Apoptosis was measured by annexin V binding/propidium iodide using fluorescence-activated cell sorter (FACS) analysis and nuclear morphology stained with the fluorescence dye, Hoechst 33342. Results: The level/concentration of apoptotic hBMSC (annexin V positive / PI negative) was increased with 10^-9 M dexamethasone (1.2% to 5.3%) and further increased with 10^-7 M, and 10^-5 M concentration (11.7% and 12.5%, respectively). The same result was observed with Hoechst 33342 staining. Conclusion: These results indicate that glucocorticoid induces apoptosis on osteoblast precursor cell, hBMSC, and may contribute to decrease bone formation
김하영,원종철,안일민,이태윤,이시열,류진숙,이성진,남궁일성,문대혁,한정희 대한내분비학회 2001 Endocrinology and metabolism Vol.16 No.4
Background: In patients with differentiated thyroid cancer treated by surgery and radioactive iodine ablation, serum thyroglobulin (Tg) and ^131I whole body scan (WBS) are recognized as being the best cooperative indicators for detection of recurrence or metastasis. However, in some cases, ^131I WBS shows no specific lesions despite elevated serum Tg. Therefore, 18-Fluorine-fluorodeoxyglucose (FDG) positron emission tomography (PET) has emerged as a useful method for the detection of ^131I WBS negative thyroid cancers. The aims of the present study are to evaluate the clinical usefulness of this technique in detection and to compare the results with ^99mTc-MIBI scintigraphy (MIBI) in cases of final results being confirmed by histologic diagnosis and other imaging methods. Methods: We conducted a retrospective analysis amon ^131I WBS negative recurred papillary thyroid carcinoma patients (male: female ratio=9:22, median age=42 yr). FDG PET was performed in 28 patients and MIBI 28 patients, 25 of whom were common to both groups. All patients had histologically proven recurrence/metastasis and negative ^131I WBS results but persistently elevated serum Tg levels. In each case overall clinical evaluations were performed including histology, cytology, thyroglobulin level, other imaging methods, posttherapy ^131I WBS and subsequent clinical course, to allow comparison with the results of FDG PET. Results: In 19 cases of patients with negative ^131I WBS, proven recurrence/metastasis lesions were detected in FDG PET. Compared with MIBI, FDG PET was found to be superior in 8 cases (including 2 patients with distant metastases). No FDG-negative/MIBI-positive tumor was observed. One FDG PET negative and MIBI negative case was proven 3 months later to be metastatic cervical lymph nodes, Sensitivities were 94.7% in the FDG PET group and 52.6% in MIBI. Diagnostic accuracy of FDG PET was superior to that of MIBI (93% vs. 62%, respectively, p=0.003). Conclusion: Our results confirmed the clinical usefulness of FDG PET for detection of ^131I negative differentiated thyroid cancers and suggested the value of FDG PET as an initial diagnostic step, rather than MIBI, in these cases