• 한국전산유체공학회지
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• 제11권4호
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• pp.75-80
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• 2006

Navier-Stokes simulation of the flow in a micro viscous pump is carried out. The micro viscous pump consists of a rotating circular rotor placed in a two dimensional channel. All simulation is carried out by using a finite volume approach, at the Reynolds number of 0.5, to study the performance of the micro viscous pump. Length of channel of the pump is varied to simulate the effects of the pumping load. Numerical solutions show that the net flow of the pump is realized by two counter rotating vortices formed on both sides of the rotor. The volume flow rate of the pump is decreased as length of the channel is increased, while the static pressure difference across the rotor is increased. The static pressure difference across the rotor is observed to be inversely proportional to the volume flow rate as inertia effects are negligibly small. The efficiency of the pump is found to reach a maximum when two counter rotating vortices on both sides of the rotor becomes to merge forming an outer enveloping vortex.

• 한국전산유체공학회지
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• 제13권2호
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• pp.14-19
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• 2008

Effects of the Reynolds and Knudsen numbers on a micro-viscous pump are studied by using a Navier-Stokes code based on a finite volume method. The micro viscous pump consists of a circular rotor and a two-dimensional channel. The channel walls are treated by using a slip velocity model. The Reynolds number is studied in the range of $0.1{\sim}50$. The Knudsen number varies from 0.01 to 0.1. Numerical solutions show that the pump works efficiently when two counter rotating vortices formed on both sides of the rotor have the same size and intensity. As the Reynolds number increases, the size and intensity of the vortex on the inlet side of the pump decrease. It disappears when the Reynolds number is larger than about Re=20. The characteristics of the performance of the pump is shown to deteriorate, in terms of mean velocity and pressure rise, as the Reynolds number increases. The Knudsen number shows a different effect on the characteristics of the pump. As it increases, the mean velocity and pressure rise decrease but the characteristics of the vortex flow remains unchanged, unlike the effect of Reynolds number.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2006년도 추계 학술대회논문집
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• pp.177-180
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• 2006

• 한국전산유체공학회지
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• 제16권1호
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• pp.90-95
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• 2011

The Navier-Stokes equations are solved to study the flow characteristics of a micro viscous pump. The viscous micropump is consisted of a stationary disk with a spiral shaped channel and a rotating disk. A simple geometrical model for the tip clearance is proposed and validated by comparing computed flow rate with corresponding experimental data. Present numerical solutions show satisfactory agreement with the corresponding experimental data. The tip clearance effect is found to become significant as the rotational speed increases. As the pressure load increases, a reversed flow region is seen to form near the stationary disk. The height of the channel is shown to be optimized in terms of the flow rate for a given rotational speed and pressure load. The optimal height of the channel becomes small as the rotational speed decreases or the pressure load increases. The flow rate of the pump is found to be in proportion to the width of channel.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2002년도 추계학술대회 논문집
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• pp.49-50
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• 2002

In micro-channels, the electro-viscous effect is caused by the electrical double layer on pressure-driven liquid flow. Velocity fields of flow inside micro-channels were measured using micro-PIV system for investigating the electro-viscous effect. De-ionized water and aqueous NaCl solutions with four different concentrations were used as working fluid in a PDMS micro-channel of $100{\mu}m$ width and $66{\mu}m$ height. The pressure gradient, dP/dx, was determined from the pre-determined input flow rate Q of syringe pump. The mean velocity $u_m$ used for calculating Reynolds number was obtained from the PIV velocity field data. These are used to plot the pressure gradient as a function of Reynolds numbers. The pressure gradient far lower concentration solution $(10^{-5}\;M)$ was higher than that for the higher concentration solution. The increase of flow resistance was about $30\%\;and\;37.5\%$ at Re=0.02 and 0.06, respectively.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2763-2768
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• 2007

Recently, as the semiconductor production technology develops, there has been growing interest in the cooling system using micro fluid pump. Among the various types of micro fluid pump, the valve-less diffuser/nozzle has been extensively studied in recent years. However, the flat-walled diffuser/nozzle flow has not been clearly looked into due to its non-linear characteristics. In this paper, the flow characteristics of the flat-walled diffuser/nozzle have been analyzed using similitude model and simulations. Similitude models are designed so that the flow pattern is same as that of 1/10 scale flow by using high viscous fluid as working fluid. The results are compared to the simulations. It is shown that the flow characteristics of 2D simulation are different from 3D simulations at high Re region, and the measured pump efficiency is highly dependent on the pressure difference as well as the channel geometry. From these results, the desirable conditions for the efficient pump is discussed.

• 한국항공우주학회지
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• 제36권5호
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• pp.483-490
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• 2008

마이크로 추진장치에서 노즐의 소형화는 많은 유동손실을 유발한다. 이러한 유동손실을 극복하기 위해 본 연구에서는 열적발산원리를 이용한 마이크로 추진장치에 대한 기초연구를 진행하였다. 움직이는 부품 없이 오직 온도구배만으로 추진제를 낮은 온도에서 높은 온도로 자체 펌핑이 가능한 열적발산장치를 설계, 제작 하였으며, 진공환경에서 누센수에 따른 맴브레인 압력구배효율을 분석하였다. 실험결과 천이영역에서는 두꺼운 맴브레인의 효율이 다소 높았으며, 자유분자영역에서는 두께에 관계없이 최대 압력구배 효율이 82%까지 증가하는 것을 확인할 수 있었다.

• 한국가시화정보학회지
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• 제9권4호
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• pp.69-73
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• 2011

Butterflies have been known to suck viscous liquids through a long, cylindrical proboscis using the large pressure difference formulated by the cyclic expansion and contraction of a muscular pump located inside their head. However, there are few studies on the liquid-feeding phenomena in a live butterfly, because it is hard to observe the internal morphological structures under in vivo condition. In this study, the dynamic motion of the pump system in a butterfly was in vivo visualized using synchrotron X-ray micro-imaging technique to analyze the liquid-feeding mechanism. The period of the liquid-feeding process is about 0.3sec. The expansion stage is about two times larger than the contraction stage in one cycle. The cyclic variation of pump volume generate large negative suction pressure and the pressure difference inside the long proboscis of a butterfly is estimated to be larger than 1atm.

• Applied Biological Chemistry
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• 제49권3호
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• pp.170-174
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• 2006

생균력 안정성이 보장되고 품질이 규격화된 농용 미생물제공급을 위하여 캡슐형 미생물제의 캡슐화 소재로 열수 추출법과 알칼리 추출법을 이용하여 다시마로부터 Na-alginate를 직접 추출하여 겔 형성능과 생균력을 검토하였다. 열수추출 alginate(HWEA)의 경우 5%의 고농도에서 겔 형성이 성공적으로 이루어진데 반해 알칼리추출 alginate(ASA)는 3% 농도에서 $992.1\;{\pm}\;0.2\;g/cm^2$의 강한 겔이 형성되는 특성을 보여 시판되고 있는 alginate(CA) 1.5% 농도의 겔과 유사한 겔 형성능을 나타내었다. 또한 ASA의 경우 추출 수율이 20%로 HWEA 보다 2배 이상 높게 나타났으며 현재 시판되고 있는 Na-alginate(CA)에 비해 비용이 11배 이상 저렴한 것으로 산출되었다. 이상의 결과로부터 ASA를 사용할 경우 값싼 비용으로 추출이 용이하며 저농도에서 겔형성능이 우수하여 최적의 농용 미생물 캡슐소재로 평가되었다. ASA 캡슐제의 생균력을 조사한 결과 81%의 생균력을 나타내어 고가의 CA 캡슐제와 동일한 생균력을 보장 할 수 있음이 입증되었다. 미세 캡슐 내 미생물 생존력을 보다 안정적으로 유지하기 위해 캡슐막의 효과를 나타낼 수 있는 보조제로 starch와 zeolite를 이용하여 생균력 증진효과를 검토한 결과 단일소재 ASA만으로 제조된 캡슐제보다 보조제를 혼합한 캡슐제 경우 세균과 효모는 생균수가 크게 증가되는 효과를 볼 수 있었다. 미생물 혼합 배양액과 상기의 최적 복합 캡슐소재를 혼합하여 캡슐화한 미생물제의 생균력을 측정한 결과 세균은 93%의 높은 생균력을 나타내었고 유산균과 효모의 경우 70% 이상의 생균력을 나타내어 본 연구를 통해 다시마로부터 직접 추출한 ASA가 고가의 시판품 alginate를 대체할 수 있는 농용 미생물 캡슐화 소재로 이용가능할 것으로 판단되었다.