• 한국가시화정보학회지
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• 제17권1호
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• pp.69-77
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• 2019

This paper introduces microfluidic manipulation of microorganism by opto-electrokinetic technique, named rapid electrokinetic patterning (REP). REP is a hybrid method that utilizes the simultaneous application of a uniform electric field and a focused laser to manipulate various kinds and types of colloidal particles. Using the technique in preliminary experiments, we have successfully aggregated, translated, and trapped not only spherical polystyrene, latex, and magnetic particles but also ellipsoidal glass particles. Extending the manipulation target to cells, we attempted to manipulate saccharomyces cerevisiae (S. cerevisiae), the most commonly used microorganism for food fermentation and biomass production. As a result, S. cerevisiae were assembled and dynamically trapped by REP at arbitrary location on an electrode surface. It firmly establishes the usefulness of REP technique for development of a high-performance on-chip bioassay system.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.3-7
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• 2009

In this study, two and three dimensional low Reynolds number flows are compared. For the two dimensional flow, an airfoil was considered and for the three dimensional low wing and full-body aircraft were considered. Because a flight condition of the aircraft is in a low Reynolds number flow, itl requires reflecting flow transition. In the two dimensional analysis, transition is predicted using en method. In the three dimensional flow, the effect of transition is included using k-w SST turbulence models.

• 대한기계학회논문집A
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• 제23권6호
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• pp.1055-1064
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• 1999

In this wort ER(electro-rheological) clutch and MR(magneto-rheological) clutch are devised and their performance characteristics such as response time and controllability are compared. As a first step, field-dependent yield stresses of ER and MR fluids are distilled in shear mode. For reasonable comparison between two clutches, a nondimensional design model is established by choosing same design parameters of gap size and number. Following the manufacturing of two clutches, field-dependent torque level, response time to step input, mechanical Power generation to electric power consumption are experimentally measured and compared. In addition, in order to investigate torque controllability of the clutches a sliding mode controller is formulated and experimentally realized. Control bandwidths of two clutches are identified and tracking control responses for desired torque trajectories are presented.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 추계 학술대회논문집
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• pp.219-224
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• 2003

An analysis procedure for the MCFC channel flow has been developed to predict the fuel cell performance. As for the electrochemical reaction, among several chemical reaction models, one that fits the data best is adopted after a comprehensive comparative study. The Wavier-Stokes, energy, and species equations are solved to obtain the velocity, temperature and concentration fields for a specified average current density. The procedure is iterative as the local current density, or the reaction rate, is allowed to vary with the gas composition. A series of calculations are then carried out to examine the effects of gas flow rate, gas composition, gas usage rate, inlet gas temperature, and average current density on the fuel cell performance. The fuel cell characteristics, such as the temperature, current density distributions, and the concentration fields, for various operating conditions are presented and discussed.

• 대한기계학회논문집B
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• 제23권7호
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• pp.801-810
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• 1999

The purpose of present research was to get characteristics and basic knowledges of electrorheological(ER) suspension. To observe behaviors of the ER suspensions. transparent conductive plates were used to visualize the flow of ER suspensions between two parallel plate electrodes. The influence of flowing speed and intensity of electric field on the ER fluid were examined in circle-shaped electric field, and it takes several hundred milliseconds that suspensions in flow cluster. The present study also conducts a numerical analysis adopting the Bingham model. It is found that simple Bingham model can not property describe the flow behavior in the parallel plates.

• 한국유변학회:학술대회논문집
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• 한국유변학회 2003년도 춘계학술발표회 논문집
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• pp.73-76
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• 2003

No Abstract, See Full Text

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2009년도 춘계학술대회 논문집
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• pp.268-268
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• 2009

고밀도 유도 결합 플라즈마를 이용한 연료 전기 분리판용 질화 장치를 플라즈마를 모사할 수 있는 3차원 전산 유체 역학 프로그램인 CFD-ACE+를 이용하여 해석하였따. 내장형 안테나 타입의 유도 결합 플라즈마의 전자 온도, 밀도 균일성, 가스 유동, 얇은 기판이 촘촘히 적재 되었을 경우의 플라즈마 특성을 모사하였다.

• 한국항공우주학회지
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• 제37권8호
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• pp.744-750
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• 2009

본 논문에서는 압전 작동기로 구동되는 무밸브 마이크로 펌프의 펌프 성능을 계산하였다. 선행연구에서 개발된 마이크로 펌프는 4층의 경량 압전 복합재료 작동기, PDMS로 된 챔버와 2개의 디퓨져로 이루어져 있다. 유한요소 해석은 압전 영역, 구조 영역 및 유체 영역을 완전 연성하여 수행되었다. 구조 및 압전 영역의 해석은 ANSYS를 사용하였으며, 유체영역의 해석은 ANSYS CFX를 사용하여 수행하였다. 작동 주파수가 10 Hz와 40 Hz인 경우에 대한 해석을 수행하여 작동 주파수가 유동 특성에 미치는 영향을 고찰하였다. 또한 300 Hz까지의 유동 해석을 통하여 작동 주파수에 따른 유량을 계산하였다.

• 한국공작기계학회논문집
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• 제12권1호
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• pp.78-83
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• 2003

Electro-rheological(ER) fluids are suspensions in which rheological properties show an abrupt change with variation of electric fields. We modeled the parallel-plates relating to ER-Valve system and yielded shear stress according to the strength of electric field. The purpose of the present study is to examine the flow characteristics of ER fluids according to the strength of electric field between parallel-plates. Then the steady relationship between pressure drop and flow rate of the ER fluids between parallel-plates under application of an electric fields was measured. The pressure drop and flow rates of ER fluids under the application of electric fields for steady flow were measured. For the experiment, we used the ER fluids, 35w% zeolite having hydrous particles and differential pressure gauge. This test reviewed experiment for the special changes of ER fluids in the steady flow condition.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2007년도 추계학술대회
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• pp.51-54
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• 2007

The induced-charge electroosmosis (ICEO) is a kind of electroosmotic flow which is generated by the electrical charge induced by an externally-applied electric field. That kind of electrokinetic phenomenon provides a nonmechanical technique to handle microscale flows and particles. In this work, we report that the ICEO-like flow is observed around two kinds of circular-cylindrical rod submerged in a dielectric liquid. The conductivity of the solution is varied by adding a surfactant. The flow field is visualized by the PIV method, and average flow speed shows a remarkable dependence on electrical input frequency. Interestingly, the characteristics of the flow are quite different from the conventional ICEO with respect to the flow direction and the locations of center of vortices.