http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Seungyoung Yang,Sung Won Ahn,Ah Reum Kang,이대웅,Sung Sik Lee,김주민,안경현,Seung Jong Lee 한국유변학회 2011 Korea-Australia rheology journal Vol.23 No.3
Dynamic self-assembly of droplets, regular structure formation of moving deformable objects in a confinement environment is a challenging problem in nonlinear dynamics and engineering patterned structure. In the current work, we investigated how the local kinematic history affects the dynamic self-assembly of picoliter-sized droplets near the expansion regions in microfluidic devices. The local kinematic history was controlled by the shape of the expansion region and characterized using computational fluid dynamics. Size-controlled aqueous droplets in light mineral oil were continuously generated at T-junction microchannel and transported toward the expansion region. The fast dynamics of the droplets was tracked using high-speed video microscopy. We found three types of dynamic droplet arrays: 1D, 2D zigzag, and irregular. The order-disorder transition was associated not only with the droplet size, but also with the controlled local kinematic history, which results in the transient deformation of droplet and droplet-droplet interactions. The present results provide us with insight into the dynamic self-assembly of droplets and could be a useful guide for practical applications of droplet-based microfluidics.
Yang, Seungyoung,Lee, Sung Sik,Ahn, Sung Won,Kang, Kyowon,Shim, Wooyoung,Lee, Gwang,Hyun, Kyu,Kim, Ju Min The Royal Society of Chemistry 2012 SOFT MATTER Vol.8 No.18
<P>We report a new phenomenon that particles are selectively entrained along the corners of a straight rectangular microchannel according to their deformabilities under viscoelastic flows of a polymer solution. The mechanism behind this phenomenon is elucidated by the competition between the wall lift force induced by the particle deformability and the elastic force of the medium at the corners. On the basis of these findings, we devise a novel label-free deformability-selective cell-separation method, which achieves the high-purity separation of rigid particles and rigidified red blood cells (RBCs) from fresh RBCs in a single step, without any active components such as an electric force or sophisticated channel design. Furthermore, our novel method can be used directly to isolate white blood cells (WBCs) from diluted whole blood with a high enrichment ratio (>300) by utilizing difference in cell deformability.</P> <P>Graphic Abstract</P><P>We report a novel method of deformability-selective particle entrainment and sorting in a rectangular microchannel using medium viscoelasticity. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2sm07469a'> </P>
Yang, Seungyoung,Kim, Jae Young,Lee, Seong Jae,Lee, Sung Sik,Kim, Ju Min Royal Society of Chemistry 2011 Lab on a chip Vol.11 No.2
<P>Particle focusing in planar geometries is essentially required in order to develop cost-effective lab-on-a-chips, such as cell counting and point-of-care (POC) devices. In this study, a novel method for sheathless particle focusing, called “Elasto-Inertial Particle Focusing”, was demonstrated in a straight microchannel. The particles were notably aligned along the centerline of the straight channel under a pressure-driven flow without any additional external force or apparatus after the addition of an elasticity enhancer: PEO (poly(ethylene oxide)) (∼<I>O</I>(100) ppm). As theoretically predicted (elasticity number: <I>El</I> ≈ <I>O</I>(100)), multiple equilibrium positions (centerline and corners) were observed for the viscoelastic flow without inertia, whereas three-dimensional particle focusing only occurred when neither the elasticity nor the inertia was negligible. Therefore, the three-dimensional particle focusing mechanism was attributed to the synergetic combination of the elasticity and the inertia (elasticity number: <I>El</I> ≈ <I>O</I>(1–10)). Furthermore, from the size dependence of the elastic force upon particles, we demonstrated that a mixture of 5.9 and 2.4 µm particles was separated at the exit of the channel in viscoelastic flows. We expect that this method can contribute to develop the miniaturized flow cytometry and microdevices for cell and particle manipulation.</P> <P>Graphic Abstract</P><P>A novel method for sheathless particle focusing in a straight microchannel, called “Elasto-Inertial Particle Focusing”, is presented in this work. Without any additional external force or apparatus, the particles are notably aligned along the centerline of a straight channel under a pressure-driven flow through the addition of an elasticity enhancer. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0lc00102c'> </P>
Khan, Ziyauddin,Park, Seungyoung,Hwang, Soo Min,Yang, Juchan,Lee, Youngsu,Song, Hyun-Kon,Kim, Youngsik,Ko, Hyunhyub Nature Publishing Group 2016 NPG Asia Materials Vol.8 No.-
<P>With the increasing demand of cost-effective and high-energy devices, sodium-air (Na-air) batteries have attracted immense interest due to the natural abundance of sodium in contrast to lithium. In particular, an aqueous Na-air battery has fundamental advantage over non-aqueous batteries due to the formation of highly water-soluble discharge product, which improve the overall performance of the system in terms of energy density, cyclic stability and round-trip efficiency. Despite these advantages, the rechargeability of aqueous Na-air batteries has not yet been demonstrated when using non-precious metal catalysts. In this work, we rationally synthesized a binder-free and robust electrode by directly growing urchin-shaped MnO2 nanowires on porous reduced graphene oxide-coated carbon microfiber (MGC) mats and fabricated an aqueous Na-air cell using the MGC as an air electrode to demonstrate the rechargeability of an aqueous Na-air battery. The fabricated aqueous Na-air cell exhibited excellent rechargeability and rate capability with a low overpotential gap (0.7 V) and high round-trip efficiency (81%). We believe that our approach opens a new avenue for synthesizing robust and binder-free electrodes that can be utilized to build not only metal-air batteries but also other energy systems such as supercapacitors, metal-ion batteries and fuel cells.</P>
Honggi Ahn,Sun Ju Kim,Seungyoung Kang,Junghun Han,Sung Oh Hwang,Kyoung-Chul Cha,Sejung Yang 대한의용생체공학회 2023 Biomedical Engineering Letters (BMEL) Vol.13 No.4
High-quality cardiopulmonary resuscitation (CPR) is the most important factor in promoting resuscitation outcomes; therefore,monitoring the quality of CPR is strongly recommended in current CPR guidelines. Recently, transesophageal echocardiography(TEE) has been proposed as a potential real-time feedback modality because physicians can obtain clearechocardiographic images without interfering with CPR. The quality of CPR would be optimized if the myocardial ejectionfraction (EF) could be calculated in real-time during CPR. We conducted a study to derive a protocol to detect systole anddiastole automatically and calculate EF using TEE images acquired from patients with cardiac arrest. The data were supplementedusing thin-plate spline transformation to solve the problem of insufficient data. The deep learning model wasconstructed based on ResUNet + + , and a monogenic filtering method was applied to clarify the ventricular boundary. Theperformance of the model to which the monogenic filter was added and the existing model was compared. The left ventriclewas segmented in the ME LAX view, and the left and right ventricles were segmented in the ME four-chamber view. Inmost of the results, the performance of the model to which the monogenic filter was added was high, and the difference wasvery small in some cases; but the performance of the existing model was high. Through this learned model, the effect ofCPR can be quantitatively analyzed by segmenting the ventricle and quantitatively analyzing the degree of contraction ofthe ventricle during systole and diastole.