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자기공명혈관조영술을 이용한 관상동맥 크기 nitinol 스텐트의 평가
현민수,Masahiro Terashima,Michael V. McConnell 순천향의학연구소 2006 Journal of Soonchunhyang Medical Science Vol.12 No.2
Background. Artifacts from stainless steel stents prohibit the assessment of stent patency with magnetic resonance angiography (MRA). Nitinol stents have less artifacts. The use of high radiofrequency flip angle (FA) sequence may improve the signal within the stents. We evaluated coronary-size nitinol stent patency with high FA MRA in the rabbit aortic model. Methods. Coronary-size nitinol stents (3.0-4.0 mm x 14-30 mm, Radius™, Boston Scientific, Natick, MA) were deployed in the aorta of six New Zealand White rabbits and imaged with MRA at day 2. A 1.5 Tesla GE MRI system (Signa, GE Medical Systems, Milwaukee, WI) with a standard extremity coil and high-performance gradients (40 mT/m, 150 T/m/s) was used. A multi-slice interleaved spiral coronary MRA sequence was used with a specially designed RF pulse to allow FA up to 140˚. Parameters were typical for patient coronary MRA studies (20 cm FOV, 0.6 x 0.6 x 3 mm, 20 interleaves, TR = 1000 ms, TE=7ms, = 60˚ , 90˚ , 120˚ , and 140˚). In-stent lumen signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) compared to adjacent muscle were analyzed. Results. The spiral coronary MRA sequence clearly imaged within the nitinol stents in all cases. Both SNR and CNR of the lumen signal significantly improved with increasing FA. SNR increased significantly from 60˚ to 140˚ (23.1+6.1 to 41.6+9.0, p < 0.01). And CNR also increased significantly(1.9±3.3 to 25.2±9.4, p = 0.01). Condusion. We could image and evaluate the coronary-size nitinol stent patency with high FA MRA in the rabbit aortic model.
P-934 : Computational Modeling of Direct Methanol Fuel Cell using FEMLAB
현민수,최종민,김상경,백동현,정두환 한국화학공학회 2007 화학공학의이론과응용 Vol.10 No.2
직접 메탄올 연료전지의 성능은 연료의 농도, 확산 속도, 압력, 온도 등에 민감한 영향을 받는다. 따라서 연료전지 시스템 구성시 변수들을 고려하여 최적화하는 데에 전산 모사는 매우 편리한 방법이다. 본 연구에서는 유한 요소법을 기반으로 한 상용코드인 FEMLAB을 사용하여 전극 층에서의 농도, 압력, 전류 밀도 분포 등을 분석하였으며 이를 바탕으로 연료전지 셀 전체의 성측을 예측하였다. 또한 채널 형상에 따른 특성을 해석하여 분리판의 최적 설계점을 예측 할 수 있었다.
직접메탄올연료전지에서 메탄올 크로스오버에 미치는 인자 연구
현민수,김상경,임성엽,이병록,백동현,정두환,Hyun, Min-Soo,Kim, Sang-Kyung,Lim, Seong-Yop,Lee, Byung-Rock,Peck, Dong-Hyun,Jung, Doo-Hwan 한국전기화학회 2008 한국전기화학회지 Vol.11 No.1
직접메탄올연료전지의 운전 변수에 따른 메탄올 크로스오버를 메탄올 농도센서를 이용하여 정량적으로 측정하였으며 실제 셀 운전 시 메탄올크로스오버 저감의 측면에서 유리한 운전조건을 분석하였다. 메탄올 농도, 전극 양단의 압력차, 전류의 크기, 온도, stoichiometry등을 변화시켜 diffusion, convection, electro-osmosis의 메커니즘별 기여도와 실제 전지 운전 조건의 영향을 함께 분석하였다. 이상의 세 가지 메커니즘 중에서 농도 차이에 의한 diffusion이 가장 큰 영향을 미쳤으며 electro-osmosis에 의한 영향은 고농도에서만 관찰할 수 있었다. The amount of methanol crossover was measured with changing the operating condition by using a liquid methanol concentration sensor. Appropriate operating condition was discussed in terms of methanol crossover. Mechanism of methanol crossover was classified into three items which are diffusion, convection and electro-osmosis. Contribution of each mechanism to methanol crossover and the effect of operating condition were analyzed with varying methanol concentration, pressure difference between anode and cathode, current, temperature, and stoichiometry of anode fuel. Among the three mechanisms diffusion affected mostly and electro-osmosis effect was observed only under high methanol concentration.
현민수,온영근,김성구,권영주 순천향의학연구소 2004 Journal of Soonchunhyang Medical Science Vol.10 No.2
We report a case cor triatriatum in a 32-year-old male diagnosed with transthoracic and transesophageal echocardiography. He complained of shortness of breath during exercise. A systolic murmur was detected on auscultation. Liver was palpable. Chest radiograph revealed enlarged pulmonary arteries and an increase in peripheral pulmonary perfusion. Electrocardiogram showed right ventricular hypertrophy. Two-dimensional and color-flow Doppler echocardiogram demonstrated right ventricular volume overload pattern, a large atrial septal defect and a membrane separating left atrium to proximal and distal chamber. Transesophageal echocardiogram confirm the correlation among atrial septum, the membrane and the pulmonary vein and the diagnosis of the cor triatriatum. The color-flow Doppler echocardiogram demonstrated the left-to-right shunt flow from the pulmonary vein to right atrium via left atrium and atrial septal defect. There was no significant stenosis on the orifice of the membrane.