http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Jin, Songwan,Kim, Jae-Hun,Yun, Won-Soo Korean Society for Precision Engineering 2015 International Journal of Precision Engineering and Vol.16 No.10
Investigating the effects of various physical stimuli on cells is important for improving the efficiency of tissue repair and regeneration. In this research, we developed a dynamic well plate system by integrating the advantages of conventional well plates and a bioreactor to provide simultaneous physical stimuli of shear stress and a static magnetic field. The dynamic well plate involving perfusion of culture medium can control hydrodynamic shear while retaining the inherent simplicity of conventional well plates. The specific well plate cover was designed to load shear stress on cells during cultivation and was built to fit over a standard six-well plate. Additionally, to investigate the effects of a magnetic field on cell proliferation, a static neodymium magnet was placed beneath each well. To assess the system developed, calf pulmonary artery endothelial (CPAE) cells were cultured using the developed system. CPAE cells under hydrodynamic shear stress conditions were elongated and aligned in the direction of the flow and the magnetic field enhanced CPAE cell proliferation. Simultaneous application of a magnetic field and shear flow in CPAE cell cultivation allowed the development of optimized culture conditions, initially for cell proliferation and then for functional expression, such as cell shape changes.
Three-dimensional migration of neutrophils through an electrospun nanofibrous membrane.
Jin, Songwan,Park, Tae-Min,Kim, Cho-Hee,Kim, Jin-Soo,Le, Binh Duong,Jeong, Young Hun,Kwak, Jong-Young,Yoon, Sik Eaton Pub. Co 2015 Biotechniques Vol.58 No.6
<P>The study of immune cell migration is important for understanding the immune system network, which is associated with the response to foreign cells. Neutrophils act against foreign cells before any other immune cell, and they must be able to change shape and squeeze through narrow spaces in the extracellular matrix (ECM) during migration to sites of infection. Conventional in vitro migration assays are typically performed on two-dimensional substrates that fail to reproduce the three-dimensional (3-D) nature of the ECM. Here we present an in vitro method to simulate the 3-D migration of neutrophils using an electrospun nanofibrous membrane, which is similar to the ECM in terms of morphology. We examined the properties of neutrophil movement and the effects of gravity and the presence of IL-8, which has been widely used as a chemotactic attractant for neutrophils. The number of neutrophils passing through the nanofibrous membrane were higher, and their movement was more active in the presence of IL-8. Also, we confirmed that neutrophils could migrate against gravity toward IL-8 through a nanofibrous membrane.</P>
저주파진동의 미세유동에의 영향 관찰을 위한 실험적 접근
김진수(Jin Soo Kim),채기운(Ki Woon Chae),배진현(Jin Hyun Bae),정영훈(Young Hun Jeong),진송완(Songwan Jin) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
Recently, there have been various studies for fluidic behavior in micro-channel due to the rapid growth of biochip and MEMs applications. In this study, the fluidic behavior in micro-channel was investigated when low-frequency vibration was given to the micro-channel environment. Especially, an actuation using flexure mechanism and piezo-electric stack actuator was used to generate vibration up to 300 Hz, which was given to the micro-channel directly. The structural characteristics of the experimental setup were investigated to identify the vibratory behavior of the micro-channel. Consequently, the influence of the low-frequency vibration on the fluidic behavior in micro-channel could be observed.
Flow Near the Meniscus of a Pressure-Driven Water Slug in Microchannels
Sungwook Kim,Songwan Jin,Jung Yul Yoo 대한기계학회 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.5
Micro-PIV system with a high speed CCD camera is used to measure the flow field near the advancing meniscus of a water slug in microchannels. Image shifting technique combined with meniscus detecting technique is proposed to measure the relative velocity of the liquid near the meniscus in a moving reference frame. The proposed method is applied to an advancing front of a slug in microchannels with rectangular cross section. In the case of hydrophilic channel, strong flow from the center to the side wall along the meniscus occurs, while in the case of the hydrophobic channel, the fluid flows in the opposite direction. Further, the velocity near the side wall is higher than the center region velocity, exhibiting the characteristics of a strong shear-driven flow. This phenomenon is explained to be due to the existence of small gaps between the slug and the channel wall at each capillary corner so that the gas flows through the gaps inducing high shear on the slug surface. Simulation of the shape of a static droplet inside a cubic cell obtained by using the Surface Evolver program is supportive of the existence of the gap at the rectangular capillary corners. The flow fields in the circular capillary, in which no such gap exists, are also measured. The results show that a similar flow pattern to that of the hydrophilic rectangular capillary (i.e., center-to-wall flow) is always exhibited regardless of the wettability of the channel wall, which is also indicative of the validity of the above-mentioned assertion.
산소 민감 발광 염료를 이용한 마이크로 채널 내에서 배양되는 세포 주변의 산소 농도 측정
이승열(SeungYoul Lee),진송완(Songwan Jin) 대한기계학회 2012 大韓機械學會論文集B Vol.36 No.5
본 논문에서는 산소 민감 발광 염료를 이용하여 마이크로 채널 내에서 세포가 배양되고 있을 때 산소농도를 측정하였다. 현재까지 알려진 여러 산소 민감 발광 염료 중 본 논문에서는 물에 잘 녹으며 장 시간 동안 사용하여도 독성이 없는 것으로 알려진 [Ru(bpy)3]<sup>2+</sup>를 사용하였으며 이와 더불어 산소 민감 염료 측정법의 단점을 보완하기 위하여 칼세인 염료를 이용하여 두 염료의 밝기 비율을 구하여 농도를 측정하였다. SCOMS 카메라와 마이크로 채널을 이용하여 캘리브레이션을 실시하고 농도와 밝기와의 관계를 구하였으며 이 관계를 이용하여 세포가 배양되는 조건에서의 배양액의 산소농도를 측정하였다. 실험 결과 채널입구에서 점점 멀어질수록 마이크로 채널 내에서 산소농도는 점점 낮아진다는 것을 관찰 할 수 있었다. In this study, we used an O<sub>2</sub>-sensitive luminescent dye to measure the O<sub>2</sub> concentration of culture media around HeLa cells cultured in a microchannel. [Ru(bpy)3]<sup>2+</sup>, which dissolves easily in water and which has no phototoxic effect, was used as the O<sub>2</sub>-sensitive dye. The ratiometric sensing method was applied by introducing calcein as the O<sub>2</sub>-insensitive dye, in order to overcome the disadvantages of intensity-based sensing. By performing calibration with an amperometric O<sub>2</sub> sensor, we could calculate the exact concentration of O<sub>2</sub> in the culture media. We applied this technique to measure the O<sub>2</sub> concentration around the cultured cells in the microchannel. As expected, the O<sub>2</sub> concentration gradually decreased as the cells moved farther away from the channel. This method is expected to be applicable to the investigation of hypoxia, which occurs commonly in scaffolds.
전반사 형광 이미지 분석을 통한 세포의 부착점 형성의 3차원 모델링
이용구(Yongkoo Lee),진송완(Songwan Jin),구상모(Sangmo Koo),전호정(Hojeong Jeon),유정열(Jung Yul Yoo) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
We carried out a time-series analysis of images which were obtained while a living cell was forming its focal contact at the bottom of the gap between the cell and the substrate. In order to visualize the contact area selectively, we adopted total-internal-reflection-fluorescence (TIRF) method, which can illuminate specimen volume within only several hundred nano-meters above the substrate. From the fluorescent intensity of the TIRF image, we could calculate the distance of the cell surface from the substrate. As a result, we visualized the change of cell-contact type from the close-contact into focal-contact with information of its vertical displacement, and presented the three-dimensional evolution process of the cell-surface-profile near the contact area during this metamorphosis.
Jeon, Hojeong,Lee, Yongku,Jin, Songwan,Koo, Sangmo,Lee, Chang-Soo,Yoo, Jung Yul Springer US 2009 BIOMEDICAL MICRODEVICES Vol.11 No.5
<P>A microfluidic device to quantify bacterial chemotaxis has been proposed, which generates a linear concentration gradient of chemoattractant in the main channel only by convective and molecular diffusion, and which enables the bacteria to enter the main channel in a single file by hydrodynamic focusing technique. The trajectory of each bacterium in response to the concentration gradient of chemoattractant is photographed by a CCD camera and its velocity is acquired by a simple PTV (Particle Tracking Velocimetry) algorithm. An advantage of this assay is to measure the velocity of a single bacterium and to quantify the degree of chemotaxis by analyzing the frequency of velocities concurrently. Thus, the parameter characterizing the motility of wild-type <I>Escherichia coli</I> strain RP437 in response to various concentration gradients of L-aspartate is obtained in such a manner that the degree of bacterial chemotaxis is quantified on the basis of a newly proposed Migration Index.</P>