• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.87-88
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• 2012

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.405-408
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• 2008

From the previous researches about flow characteristic of micro-nozzle, we found that viscosity and back pressure induced heavy losses in micro nozzle. To overcome thess losses, we began to study new conceptual micro propulsion system that is thermal transpiration based micro propulsion system. It has no moving parts and can pump the gaseous propellant by temperature gradient only (cold to hot). Most of previous research on thermal transpiration is in its early stage and mainly studied for application to small vacuum facility or gas chromatography in ambient condition using nanoporous material like aerogel. In this study, we focus on basic research of propulsion system based on thermal transpiration using polyimide material in vacuum conditions.

• 한국전기전자재료학회논문지
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• 제14권12호
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• pp.994-1000
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• 2001

In this paper, using micro-stereolithography technology, I fabricated a liquid analyzer to measure ion concentration of a solution. Micro-stereolithography is a technology to fabricate 3-dimensional structure by applying laser beam on liquid photo-polymer. This technology makes it possible to do preassemble fabrication without any extra assembling step after the process. So, the liquid analyzer could be fabricated at very low cost with very simple process by micro-stereolithography technology. The liquid analyzer consists of a chamber for containing the solution, a pump using piezoelectric effect of PZT disk, a static mixer and a sensor for measuring ion concentration using Pt electrodes.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.866-870
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• 2008

In this study, we designed cold gas propulsion system with minimum 0.25 mm nozzle and micro-thrust measurement system to analyze flow characteristic of micro propulsion system in ambient and vacuum condition. Argon and Nitrogen are used for propellant and the result of experiments is compared with CFD analysis and theory. But there is a point where reduced scale versions of conventional propulsion systems will no longer be practical. Therefore, a fundamentally different approach to propulsion systems was taken. That is thermal transpiration based micro propulsion system. It has no moving parts such as lubricants, pressurizing system and can pump the gaseous propellant by temperature gradient only(cold to hot). We are advancing basic research of propulsion system based on thermal transpiration in vacuum conditions and had tried experiment process and theoretical access in advance. To characterize membrane of Knudsen pump, we select Polyimide material that has low thermal conductivity(0.29 W/mK) and can stand high temperature($300^{\circ}C$) for long time. And we fabricated hole diameter 1, 0.5, 0.2, 0.1 mm using precision manufacturing. Experimental results show that pressure gradient efficiency of Knudsen pump is increased to maximum 82% according to Knudsen number and thick membranes are more effective than thin membranes in transition flow regime.

• 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.

• 센서학회지
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• 제10권4호
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• pp.232-238
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• 2001

본 논문에서는 Stereolithography 기술을 이용하여 마이크로 펌프를 제작했다. 펌프는 구동에 PZT를 사용하고, diffuser/nozzle 개념의 non-movable 밸브를 사용하여 제작했다. 펌프의 크기는 챔버$14mm{\psi}$, diffuser/nozzle의 크기는 좁은 쪽의 구멍은 $0.5mm{\psi}$, 넓은 쪽의 구멍은 $1mm{\psi}$로 제작하고, 챔버의 깊이는 1.2mm이다. 펌프는 주파수 100Hz, 인가 전압 $90{\sim}250Vp-p$ 사이에서 구동시켜, 그 동작을 확인했다. 측정 결과, 펌핑 용액이 에탄올 일 때, 인가 전압 200V, 100Hz로 구동했을 때, 53mm의 수두차를 나타냈다.

• 한국정밀공학회지
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• 제23권2호
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• pp.129-137
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• 2006

Polymer micro-fluidic devices were fabricated with laser processes. A UV laser and a femto laser were used to machine polymer micro-fluidic structures directly. This laser direct machining process suits the need of rapid prototyping, as in many applications changes from the original design are often required. As examples, two polymer micro-systems were developed: a micro-check valve and a micro diffuser pump. The micro fluidic devices can be applied for many applications such as clinical diagnostics and drug delivery. Advantages and disadvantages using polymers as a material for micro-fluidic applications are 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.

• 한국생산제조학회지
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• 제21권3호
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• pp.362-367
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• 2012

Though a micro pump is a crucial element in miniaturized bio-fluidic systems or drug delivery systems, most of the conventional micro pumps still have some limitations to miniaturize their controller system and to obtain the sufficient back pressure which can rise over the inner pressure of human body or experimental animals. In this paper, to overcome these limitation, a new PZT disc and its controller were designed and fabricated to get the sufficient flowrate and the back pressure with guaranteeing embeddability of the controller into pumping body. The amplitudes of the disc deflections were as large as 40 ${\mu}m$ at 200 V - 100 Hz condition. As results of experiments, the flow rate and the back pressure increase when the frequency increases. The obtainable maximum flow rate and back pressure are 5.2 ml/min at 95 Hz and 13.14 kPa at 90 Hz respectively.

• 설비공학논문집
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• 제24권3호
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• pp.256-264
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• 2012

A general procedure for the optimal design of a micro-channel heat exchanger for heat pump systems is presented. For this design, a performance analysis program that can reflect the various geometric variables of the micro-channel heat exchanger was developed. The deviation between simulated and experiment results of previous research was within 4% for the heat transfer rate. To prove the feasibility of the optimal design process, the performance of the reference heat exchanger was compared to that of the optimized heat exchanger. The $JF_{air}$ and PECv of the optimized heat exchanger were enhanced by 14% and 26%, respectively.