• IMMUNE NETWORK
• /
• 제13권2호
• /
• pp.43-54
• /
• 2013

Over the past 40 years, flow cytometry has emerged as a leading, application-rich technology that supports high-resolution characterization of individual cells which function in complex cellular networks such as the immune system. This brief overview highlights advances in multiparameter flow cytometric technologies and reagent applications for characterization and functional analysis of cells modulating the immune network. These advances significantly support highthroughput and high-content analyses and enable an integrated understanding of the cellular and molecular interactions that underlie complex biological systems.

• 드라이브 ㆍ 컨트롤
• /
• 제16권4호
• /
• pp.65-73
• /
• 2019

In this study, flow analysis and fluid-solid interaction analysis were conducted on a hollow fiber membrane module used for analysis of dehumidification characteristics. To ensure the reliability of the flow analysis results, the dehumidification experiment was performed under the temperature of 30℃ and relative humidity of 30% RH. The results of the dehumidification experiments were compared with the flow analysis results. The results of dehumidification experiments and flow analysis had a difference of approximately 5%. A 1-Way fluid-solid interaction analysis with various materials was conducted. From the results, it was found that the baffle with the largest shape deformation (polyethylene material) was subjected to 2-way fluid-solid interaction. The analysis of fluid flow and dehumidification characteristics were analyzed according to the shape deformation of the baffle.

• 대한기계학회논문집B
• /
• 제27권5호
• /
• pp.635-643
• /
• 2003

Parametric study for the analysis of performance characteristics of a planar -type solid oxide fuel cell(SOFC) using computational flow analysis is conducted. A planar -type SOFC, which is composed by two gas channels (fuel and ai.) and one set of anode-electrolyte-cathode assembly, is modeled as a two -dimensional isothermal case. Results of computational analysis of flow field including distributions of mass fractions in gas channels are used to the performance analysis of the fuel cell. Flow analysis makes it possible to consider current density distributions along the length of the cell in the process of performance analysis of the SOFC. As results of parametric study, it is found that the mole fraction of fuel at the inlet of fuel channel, operating pressure and temperature are closely related to the performance characteristics of SOFC.

• Journal of Biosystems Engineering
• /
• 제42권1호
• /
• pp.1-11
• /
• 2017

Purpose: Methods: Three-dimensional CFD modeling was conducted to analyze the flow structure and discharge flow rate corresponding to the variation in the geometry of the flow channel in a microtube. Additionally, experiments were carried out, and the discharge flow rate was measured at various inlet pressures and inclination angles of the microtube. Results: The quantitative data of velocity distribution and discharge flow rate were obtained. As the width and length of the microtip increased, the discharge flow rate decreased significantly because of the increase in the loss of pressure along the microtube. As the depth of the microtip increased, the flow rate also increased because of the reduction in the flow resistance. However, in this analysis, the variation in the angle of the microtip did not influence the flow rate. From the experimental results, it was observed that the flow rate increased linearly with the increase in the inlet pressure, and the effects of the inclination angle were not clearly observed in those test cases. The values of the flow rate obtained from the experiments were significantly lower than that obtained from the CFD analysis. This is because of the distortion of the shape of the flow path inside the microtube during the fabrication process. The distortion of the flow path might decrease the flow cross-sectional area, and it would increase the flow resistance inside the microtube. The variation in the flow rate corresponding to the variation in the inlet pressure showed similar trends. Conclusions: Therefore, the results of the numerical analysis obtained from this study can be efficiently utilized for optimizing the shape of the microtip inside a microtube.

• 수산해양기술연구
• /
• 제38권1호
• /
• pp.43-57
• /
• 2002

본 연구는 고성능 전개판을 개발하기 위하여 전개판 주변의 유동장을 계측할 수 있는 해석 방법을 제시하고자 하였다. 실험 방법으로는 CFD를 이용한 유동장의 수치 해석과 유동장의 정량적, 정성적 계측이 가능한 PIV 실험방법을 사용하였다. 본 실험에서는 전개판 주변의 가시화된 영상을 PIV 기법을 이용한 화상처리로 유동특성을 해석하였으며, 이 결과를 CFD에 의한 해석 결과와 유동 패턴을 비교하였다. 또한, 회류 수조에서의 양력 계수 및 항력계수의 계측 결과를 상호 비교 하였다. 그 결과, 수치 해석된 결과와 PIV의 실험 결과는 정성적으로 매우 잘 일치하였으며, 물리적으로 타당성을 확인할 수 있었다. 그 결과는 다음과 같다. (1) 전개판의 유동장 분석을 위하여 레이저 광원을 이용한 가시화 실험을 실시하고, PIV 기법으로 화상분석을 실시하였으며, 유동입자의 흐름으로도 충분한 정성적인 유체운동의 경향을 파악할 수 있었다 (2) PIV해석결과가 정량적인 결과이므로 이를 다양한 후처리 방법을 통해 속도벡터장, 순간 유동장, 평균 와도로 나타내어 유동장의 변화를 확인할 수 있었다. (3) 최대전개력계수가 나타난 영각 24$^{\circ}$에서 비교한 CFD와 PIV 해석 결과, 유동 패턴은 유사하였고, 두 경우 모두 전개판 후연에서 약간의 경계층 박리가 발생하였으나 양호한 흐름을 보였다. (4) PIV에 의한 속도 벡터도, 순간 유선도, 평균 와도로 후처리한 결과, 영각 24$^{\circ}$에서부터 경계층 박리 현상이 일어나기 시작하여, 영각 28$^{\circ}$이상이 되면 심하게 전연으로 발생지점이 이동하게 되고, 그 폭도 확대됨을 확인할 수 있었다.

• 대한기계학회논문집B
• /
• 제28권3호
• /
• pp.330-337
• /
• 2004

Analysis of flow phenomena in a centrifugal compressor impeller has been carried out with numerical simulation to understand the physics of flow near stall. Near stall point, tip leakage flow spills ahead of the leading edge of adjacent blade and other leakage flow passes over the clearance of the adjacent blade instead of rolling up into vortex within the passage. The tip leakage flow at the mid chord of impeller blade impinges against the pressure surface of the adjacent blade and then rolls up into vortex within the passage, which blocks the flow passage and generates viscous loss. The spillage of leakage flow ahead of the adjacent blade generates the recirculation of flow entering the impeller, which causes the power transferred into the flow by the impeller to decrease and blocks the flow passage. Near diffuser hub wall, flow recirculation occurs. As operating point goes to stall point, the core of recirculation approaches the impeller exit The length rises to peak point and then drops with mass flow reduction, while the height steadily rises.

• 한국자동차공학회논문집
• /
• 제9권1호
• /
• pp.102-111
• /
• 2001

To describe the air flow characteristics within an air cleaner cover and mass air flow sensor (MAFS) entry region installed in a 3.0L engine air induction system, flow visualization, velocity and turbulence intensity measurements were taken in several view planes. A detailed knowledge of the interaction between the design parameters and the flow structures will enhance our understanding of the motions within the flow field and enable engineers to optimize the induction system and reduce the signal-to-noise ratio in the MAFS output. Emphasis is placed on the analysis of coherent motions and the controlling parameters which affect the air flow in the MAFS entrance region over a flow rate of 13-240 kg/hr. The high speed motion pictures illustrated that the air flow generated within the air cleaner cover under steady state condition is quite complex. In both axial and radial planes of the main passage it was found that the flow pattern is remarkably influenced by the air cleaner cover and main passage configuration. A comparison of the flow patterns and measurements in the original and modified air cleaner cover is presented. Measurements from the MAFS indicated an significant reduction in pressure drop and signal noise for the modified cover as compared with the original cover, over an air flow rate of 13-240 kg/hr.

• 연구논문집
• /
• 통권29호
• /
• pp.123-130
• /
• 1999

Flow divider valve는 한 개의 공급라인에서 두 개 이상의 출력라인으로 유압유를 일정비율로 분배하는 유압제어밸브로서 하중압력이나 공급압력 등에 관계없이 항상 일정비율의 유량분배가 가능해야 한다. 현재 상용제품의 유량분할 정확도는 90~95% 수준이며, 이러한 유량분할오차(Flow dividing error)는 유압시스템에 누적오차로 작용하여 많은 문제점을 야기시키고 있어 보다 고정밀 유량제어가 가능한 Flow divider valve 개발이 요구된다. 본 연구에서는 외력을 고려한 스푸울의 거동을 수치적으로 정확하게 조사하여 Flow divider valve의 동특성을 규명함과 동시에 유량분할 오차를 감소시키는 최적설계방안을 제시하고자 한다. 동특성 해석은 일정한 하중저항을 입력신호로 작용하는 경우에 대해서 제시하였으며, 이때의 고정오리피스와 가변오리피스의 단면적 및 스푸울의 단면적 변화에 따른 동특성의 변화를 조사하였다.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2008년도 정기 학술대회
• /
• pp.152-155
• /
• 2008

The blood flow characteristics have been closely related to various cardiovascular diseases, it is very important to predict them accurate enough in an efficient way. Thus, this paper proposes a one-dimensional spectral element model for the blood flow through blood vessels. The spectral element model is formulated by using the variational method. The nonlinear terms in spectral element model are all treated as the pseudo-force and an iterative solution method is applied in the frequency domain.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2000년도 추계학술대회논문집B
• /
• pp.416-421
• /
• 2000

The performance of gas turbine engines is affected by instabilities, like as rotating stall and/or surge. Rotating Stall is a transient intermediate stage between normal flow and complete flow breakdown leading to engine surge. Rotating Stall is associated with large amplitude nonaxisymmetric flow variations rotating around the compressor annulus. This paper presents the evolutions of stall propagation in a compressor cascade by numerical analysis. The flow phenomena due to stall cells and propagation speed are examined using 2 dimensional Navier - Stokes equations.