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해상도 향상을 위한 4.7 T 자기공명유속계 용 솔레노이드 RF 코일 개발
양병권(Byungkuen Yang),조지현(Jee-Hyun Cho),송시몬(Simon Song) 한국가시화정보학회 2016 한국가시화정보학회지 Vol.14 No.2
Magnetic resonance velocimeter (MRV) is a powerful tool to non-invasively measure the velocity of a fluid flow in various fields ranging from medicine to engineering. However, since the demands for accurate measurement in the solid/liquid interface for cardiovascular diseases and porous media increase, the improvement of spatial resolution is required. In this study, a solenoid RF coil is developed for high spatial resolution measurement. The signal-to-noise ratio in solenoid RF coil is increased seventeen times better than that in commercial coil. Moreover, the velocity distribution of Hagen-Poiseuille flow is measured with in-plane resolution of 36 ㎛ by 36 μm and the accuracy of the measured velocity is compared with theoretical distribution of the laminar flow. Flow rate calculated by MRV is estimated with the flow rate injected by syringe pump.
자기공명유속계 해상도 향상을 위한 4.7T MRI용 솔레노이드 RF코일 개발
송시몬(Simon Song),양병권(Byungkuen Yang),조지현(Jee-Hyun Cho) 한국가시화정보학회 2016 한국가시화정보학회 학술발표대회 논문집 Vol.2016 No.4
Magnetic resonance velocimetry (MRV) is a powerful tool to non-invasively measure the velocity of fluid flow in many fields ranging from medicine to engineering and biology. However, since the demands for accurate measurement in the solid/liquid interface for cardiovascular diseases and porous media increase, the improvement of spatial resolution is necessary. In this study, a solenoid RF coil is developed for high spatial resolution measurement. The signal-to-noise ratio in solenoid RF coil is increased seventeen times better than that in commercial coil. Moreover, the velocity distribution of hagen-poiseuille flow is measured with in-plane resolution of 36㎛ by 36㎛.
자기공명유속계를 이용한 진공청소기 노즐 아래 카펫 내부 유동의 3차원 가시화
이지수(Jeesoo Lee),양병권(Byungkuen Yang),송시몬(Simon Song) 한국가시화정보학회 2015 한국가시화정보학회 학술발표대회 논문집 Vol.2015 No.12
3D mean flow field inside a carpet induced by a suction nozzle of a vacuum cleaner was visualized using magnetic resonance velocimetry (MRV). Nozzle with three different shape of nozzle lips were tested and their effects on a flow distribution within carpet were analyzed. Measured data were validated by comparing flow rate computed from MRV data with flow meter value measured during experiments. We successfully observed distinct flow patterns caused by the geometry of each nozzle at least qualitatively. Distributions of incoming velocities along the carpet depth under the boundary of nozzles were investigated for the qunatitative analysis. We found that the nozzle with longer lips tends to generate relatively uniform profile than the nozzle with shorter lips. Furthermore the shorter lips induces stronger incoming flow at near the carpet surface.
자기공명유속계를 이용한 카펫 내부 유동장의 3차원 가시화
이지수(Jeesoo Lee),양병권(Byungkuen Yang),송시몬(Simon Song) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
3D mean flow field inside a carpet induced by a suction nozzle of a vacuum cleaner is visualized using magnetic resonance velocimetry (MRV). Three types of nozzle with different shape of nozzle lips were used and the effects of nozzle geometry on a flow distribution within carpet were studied. Measured data were validated by comparing flow rate computed from MRV data with flow meter value measured during experiments. Distinct flow patterns between nozzles were observed and the suction velocity distribution inside the carpet below the nozzles were successfully observed. Also we were able to find the nozzle with longer lips tends to generate uniform flow distribution along the depth of the carpet. On the other hand, the shorter lips induces more flow at near the carpet bottom. Furthermore the tapered lips of nozzle #2 induces more flow than non-tapered which may be the effect of twice longer lips.
자기공명유속계를 이용하여 예측한 벽면전단응력의 정확도 평가 기준 개발
이지수(Jeesoo Lee),고승빈(Seungbin Ko),양병권(Byungkuen Yang),조지현(Jee-Hyun Cho),송시몬(Simon Song) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
Wall shear stress (WSS) exerted on a blood is one of the key factors associated with cardiovascular diseases. It has been found that magnitude and temporal oscillation of WSS can be correlated with atherosclerosis, aortic dilatation and vascular remodeling. Magnetic resonance velocimetry (MRV) is currently the most advanced technique that can noninvasively estimate temporal and volumetric distribution WSS in vivo. Numerous clinical studies have been reported which determined WSS in various vascular region based on MRV measurements. However, it is difficult to discover the descriptions about the absolute accuracy of WSS in literatures, especially in clinical studies because the true value of WSS is unknown. Therefore, a facile criterion for assessing the accuracy of estimated WSS for MRV measurements with unknown WSS would be valuable. In this research, we propose a novel criterion called Reynolds resolution to assess the absolute accuracy of WSS estimated from MRV data. It is described with measurement parameters and thus, can readily be calculated. We investigated the relation between the Reynolds resolution and WSS accuracy by measuring pressuredriven laminar circular tubing flows and a proportional relation was found indicating that the Reynolds resolution could have its potential to be used for predicting the absolute errors of MRV-estimated WSS.