http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
외부 가스 유동에 의한 미소 액적 내부 유동 제어 및 가시화
허영근(Young Gun Heo),허효원(Hyo Weon Heo),전영훈(Young Hun Jeon),서용권(Yong Kweon Suh) 한국가시화정보학회 2010 한국가시화정보학회 학술발표대회 논문집 Vol.2010 No.11
We conducted experimental visualization and numerical simulations of flow inside a droplet subjected to an external gas flow. The purpose of this study is to confirm a flow-control method provided by agas flow over a droplet, which may be used in the enhancement of the semiconductor performance, in the case where the semiconductors are manufactured by the principle of inkjet printing. Our ultimate target is to remove the coffee-stain effect and make the osc align in the direction of current in between a pair of micro electrodes.
패브릭 블레이드를 적용한 100W급 수직축 풍력발전기 개발
허영근(Young-Gun Heo),정원혁(Won-Hyuk Jung),정종현(Jong-Hyun Jeong) 한국산학기술학회 2023 한국산학기술학회논문지 Vol.24 No.10
본 논문은 패브릭을 이용한 100 W급 사보니우스형 수직축 소형 풍력발전기의 개발에 대한 내용이다. 패브릭 소재를 적용하여 블레이드 파손에 의한 사고를 예방하고 저속회전이 가능한 사보니우스형태를 적용하여 로터 회전에 의한 위협감을 줄이고자 하였다. 기본 설계를 통하여 로터의 형상 치수를 결정하고 유동해석을 통하여 정격 조건에서의 정격 출력을 확인하였다. 그리고 구조적 안전성을 고려하기 위하여 정격 출력 조건과 극한 조건에 대한 구조해석을 수행하였으며 정격 풍속 조건에서의 안전율은 30.4 이상, 극한 풍속 조건에서의 안전율은 10.5로 구조적 안전성을 확인하였다. 유동해석 결과, 106.8 W의 출력을 확인하였으며 이를 토대로 풍력발전기 로터를 제작하였다. 풍동시험을 통하여 로터의 출력을 검증하였으며 개선된 로터의 풍동 시험 결과는 107.9 W가 나타남을 확인하였다. This paper presents the development of a 100 W Savonius small VAWT (Vertical Axis Wind Turbine) using fabric blades. The aims were to prevent accidents caused by blade damage using fabric material and enable low-speed rotation by adopting the Savonius-type rotor, reducing the hazards associated with rotor rotation. The dimensions of the rotor were determined through the basic design. Computational Fluid Dynamics (CFD) confirmed the rated power output under rated operating conditions. In addition, structural analysis was performed for both rated wind speed conditions and extreme wind speed conditions to assess the structural safety. The safety factors were 30.4 or higher at rated wind speed conditions and 10.5 at extreme wind speed conditions, confirming the structural integrity. The CFD results confirmed the power output of 106.8 W. The wind turbine rotor was manufactured based on the CFD results. Wind tunnel testing was conducted to validate the rotor performance, and the wind tunnel test results from the improved rotor achieved 107.9 W.
허영근(Young Gun Heo),전영훈(Young-Hun Jeon),서용권(Yong Kweon Suh) 한국가시화정보학회 2010 한국가시화정보학회지 Vol.7 No.2
In this paper we report the method of visualizing and measuring the fluid flow within a small droplet of millimeter size. We use a vertical laser sheet in visualization of the micrometer size and special attention is given to the arrangement of microscope to obtain clear images. Then we use a PIV technique to measure the velocity of the internal flow from the images taken. Since the droplet is of spherical shape, the images represent highly deteriorated picture of the real objects due to the refraction phenomenon. In order to compensate the refraction, we in this study developed two kinds of methods for the real velocity. In the first method, the refracted images are directly used to obtain the velocity in the image space, and then the velocity is transformed to the real space. In the second method the images are first transformed to the real-space objects, and then the PIV is used to measure the velocity field. We compared the two results to prove the usefulness of the compensation technique.
포트란-CFX 연동해석 기법을 이용한 비정상 DC 전기삼투 유동 가시화
허영근(Young Gun Heo),정종현(Jong Hyeon Jeong),서용권(Yang Kweon Sub) 한국가시화정보학회 2011 한국가시화정보학회지 Vol.9 No.4
In this study, we present methods of coupling a commercial code, ANSYS CFX, and the user Fortran codes for solving an unsteady electro-osmotic flow around a pair of electrodes, receiving DC, attached to the top and the bottom walls of a two-dimensional cavity. We developed a module of Fortran programs for solving the ion-transport equations as well as the Poisson equations for the potential to be used in coupling with the CFX. We present how the developed codes are applied to solving the transient DC electro-osmotic flow problem within a simple cavity. We also address various problems encountered during the development process and explain why such problems are raised.
CFX 코드를 사용한 비정상 DC 전기삼투 유동 해석기법 개발
허영근(Young Gun Heo),전영훈(Young Hun Jeon),정종현(Jong Hyeon Jeong),서용권(Yong Kweon Suh) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
In this study, we couple a commercial code, ANSYS CFX and Fortran codes for solving electro-osmotic flows around a pair of electrodes receiving DC potentials attached to the top and bottom walls of a rectangular domain. Up to now, no work has been presented in the literature which obtained the solutions of the electro-osmotic-flow problems by using the CFX. Difficulties in this techniques are: Firstly, the ion transport equations (i.e., Nernst-Planck equations) must be solved by using the general transport equation provided by CFX, but in most often there is numerical instability in treating the source terms. Secondly, to calculate the source term we need to evaluate the electric field which must be obtained from a separate Fortran code in terms of the potential which is given from the solution of the Poisson equation. In this case, care must be given to the computer-memory problem. In this study, we develop a module of Fortran programs which are used in solving the ion transport problem in coupling with the CFX. We will present how the developed code is applied to solving the dc electro-osmotic problem within a simple geometry. We also address various problems encountered during the development process and explain how such problems are tackled.
허영근(Young Gun Heo),서용권(Yong Kweon Suh) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
In this paper we report the method of visualizing and measuring the fluid flow within a small droplet of millimeter size. We use a vertical laser sheet in visualization of the micrometer size and special attention is given to the arrangement of microscope to obtain clear images. Then we use a PIV technique to measure the velocity of the internal flow from the images taken. Since the droplet is of spherical shape, the images represent highly deteriorated picture of the real objects due to the refraction phenomenon. In order to compensate the refraction, we in this study developed two kinds of methods for the real velocity. In the first method, the refracted images are directly used to obtain the velocity in the image space, and then the velocity is transformed to the real space. In the second method the images are first transformed to the real-space objects, and then the PIV is used to measure the velocity field. We compared the two results to prove the usefulness of the compensation technique.
Mixing in a Microchannel by using Induced-charge Electro-osmosis
전영훈(Young Hun Jeon),허영근(Young Gun Heo),정원혁(Won Hyuk Jung),수레수 알라파티(Suresh Alapati),서용권(Yong Kweon Suh) 한국가시화정보학회 2010 한국가시화정보학회지 Vol.8 No.4
This paper presents an experimental study on the performance of a micro-mixer using AC electro-osmotic flow. The microchannel is made of PDMS for the side and top walls and glass patterned with ITO for the bottom wall. We first investigated the effect of the applied potential as well as the frequency on the slip velocity. We have found that the slip velocity is roughly proportional to the applied voltage in line with the Helmholtz-Smoluchowski equation and there is an optimum frequency at which the slip velocity becomes maximized. To find the optimum parameters for mixing device we tested our device for various design parameters. It turned out that the best mixing effect is obtained approximately when the electrode angle is 30°, electrode width 200 ㎛, and the frequency of power supply 700 ㎐.