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이관현 ( Lee Gwan Hyeon ),김여주 ( Kim Yeo Ju ),김상진 ( Kim Sang Jin ) 대한내과학회 2003 대한내과학회지 증례 특집호 65-5 부록3 Vol.0 No.-
maternal skeletal calcium restores and underlying genetic susceptibility may cause it. Recently it has been proposed that PTH-related protein may be an important causative factor. There are three types of the pregnancy associated osteoporosis, a transient
와후류 저감을 위한 날개 끝 홈 형상에 대한 풍동실험연구
진정현,오세종,이관중,권기범 한국항공우주학회 2013 한국항공우주학회 학술발표회 논문집 Vol.2013 No.4
항공기의 이·착륙 시 선행 항공기의 날개에서 발생한 강한 와후류는 후행항공기의 안정성에 영향을 준다. 본 연구에서는 와후류 저감을 위한 날개 끝 홈 형상을 제안하고, 풍동실험을 통하여 날개 끝 홈 형상의 변화에 따른 공력 특성과 PIV를 통한 와후류의 속도장을 측정하였다. 본 실험은 공군사관학교의 중형풍동을 사용하여 실험하였다. 실험 환경은 레이놀즈 수가 1.1×10<SUP>6</SUP>이며, 받음각은 0°, 5°, 8°, 11°로 변화를 주어 공력을 측정하였다. 날개 뒤 와후류는 시위거리의 10배 뒤인 지점에서 PIV를 사용하여 속도장을 측정하였다. 날개 끝 홈 형상은 와후류 강도 저감의 효과가 있음을 확인하였다. The shedding of strong vortices generated in take-off and landing can affect the safety of following aircraft. In this study, chipped wingtip shape for wingtip vortex attenuation was suggested and wind tunnel test was conducted to evaluate the aerodynamic characteristics and velocity field of vortex using PIV. This experiment was performed in Korea Air Force Academy Subsonic Wind Tunnel Laboratory. Chord based Reynolds number was 1.1×10<SUP>6</SUP> and angle of attack was 0°, 5°, 8°, 11° for aerodynamic characteristics. At 10 chord distance behind the wing, velocity field was measured using PIV. It was found that the chipped wingtip shape can mitigate the wingtip vortex strength.
진정현,오세종,이관중,권기범 한국항공우주학회 2013 한국항공우주학회 학술발표회 논문집 Vol.2013 No.4
항공기의 이·착륙 시 선행 항공기의 날개에서 떨어져 나온 강한 와후류는 후행 항공기에 심각한 위험을 줄 수 있다. 이러한 와후류로 인한 위험도를 줄이기 위하여 본 연구에서는 날개 끝 홈 형상을 제안하고 이것의 기초적인 입증을 위하여 수치해석이 수행 되었다. 수치해석은 SIMPLE 알고리즘에 기반한 비압축성 Navier-Stokes 해석자를 사용하였다. 난류 효과를 평가하기 위하여 Reynolds stress model을 사용하였다. 날개 끝 홈 형상은 기본 형상에 비하여 와후류의 강도를 현저하게 저감시켰다. 본 연구의 다양한 날개 끝 홈 형상변화를 통하여 기본형상 대비 항력의 증가량과 와후류의 접선방향 속도성분의 감소량이 상반관계에 있음을 확인하였다. The shedding of strong vortices generated in take-off and landing poses serious hazard for the following aircraft. To circumvent the vortex wake hazard, a chipped wingtip shape was suggested and a series of numerical simulations were conducted to verify its conceptual validity. The numerical simulation was performed by using incompressible Navier-Stokes solver with pressure based SIMPLE algorithm. Reynolds stress model was employed to evaluate turbulence effects. It was found that the trailed vortices of chipped wingtip shapes were more dissipative than those of the baseline wingtip shape. It was found that there was a trade-off relationship between tangential velocity reduction and drag increase.
Nho, Hyun Woo,Yang, Nuri,Song, Jaewoo,Park, Joon Shik,Yoon, Tae Hyun Elsevier 2017 Sensors and actuators. B Chemical Vol.249 No.-
<P><B>Abstract</B></P> <P>Shape-based separation capabilities of a novel pinched flow fractionation device with a tilted sidewall and vertical focusing channels (t-PFF-v) were demonstrated for (1) spherical and disc-shaped polystyrene (PS) particles; (2) platelets (PLT) and red blood cells (RBC); and (3) singlet, doublet, and triplet clusters of disc-shaped PS particles. The tilted sidewalls and vertical focusing channels of the t-PFF-v device allowed us to perform enhanced separation of non-spherical particles. Using this t-PFF-v device with a W<SUB>p</SUB> (pinched segment width) of 20μm and 15μm, not only spherical (diameter of 2μm) and disc-shaped (thickness of ∼2μm, diameter of ∼5.0μm) PS particles but also PLTs and RBCs from diluted blood were well separated with good separation resolutions (R<SUB>disc,sphere</SUB> =1.40 and R<SUB>PLT,RBC</SUB> =1.28). Additionally, time-lapse images of flowing particles indicated that both disc-shaped PS particles and RBCs are probably having type I orientation in the pinched segment (i.e., leaning against the tilted sidewalls at the pinched segment). Moreover, we observed streamlines of singlet, doublet, and triplet clustered disc-shaped PS particles, which suggested that these clustered particles could be well separated according to their aspect ratio. The doublet or triplet clustered PS particles are probably lay on the floor and rotated at the pinched segment (type II orientation). We believe that this shape-based separation capability achieved by the t-PFF-v device can be utilized for many application areas, such as medical, biological, material and colloidal sciences.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Shape-based separation capability of t-PFF-v device was demonstrated for spherical and disc-shaped PS particles. </LI> <LI> By using t-PFF-v device, blood components such as platelets (PLTs) and red blood cells (RBCs) were separated. </LI> <LI> Singlet, doublet, and triplet clusters of disc-shaped PS particles were also separated by using t-PFF-v device. </LI> <LI> The tilted sidewalls and vertical focusing channels of the t-PFF-v device allowed us to perform enhanced separation of non-spherical particles. </LI> <LI> Time-lapse images suggest that both disc-shaped PS particles and RBCs are leaning against the tilted sidewalls at the pinched segment. </LI> </UL> </P>