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Effect of Intermediate Metal on the Methanol Gas Sensitivity of ITO Thin Films
이학민,허성보,공영민,김대일,Lee, H.M.,Heo, S.B.,Kong, Y.M.,Kim, Dae-Il The Korean Vacuum Society 2011 Applied Science and Convergence Technology Vol.20 No.3
RF 마그네트론 스퍼터와 DC 마그네트론 스퍼터를 병행하여 ITO/Au/ITO, ITO/Cu/ITO, 그리고 ITO/Ni/ITO 박막을 유리기판 위에 증착하였다. 증착 후 진공열처리를 통하여 층간 금속 층이 ITO박막의 메탄올 검출 민감도에 미치는 영향을 분석하였다. 모든 박막센서의 두께는 100 nm로 동일하게 ITO 50 nm/metal 10 nm/ITO 40 nm로 제작되었고 메탄올 농도는 100에서 1,000 ppm까지 달리하였다. ITO/Au/ITO 박막센서가 가장 높은 민감도를 보임으로써 ITO/Au/ITO 다층박막이 기존의 ITO메탄올 센서를 대체할 수 있는 센서임을 확인하였다. ITO thin films and gold (Au), copper (Cu) and nickel (Ni) intermediate ITO multilayer (ITO/Au/ITO, ITO/Cu/ITO, ITO/Ni/ITO) films were deposited on glass substrates with a reactive radio frequency and direct current magnetron sputtering system and then the effect of intermediate metal layer and annealing temperature on the methanol gas sensitivity of ITO films were investigated. Although both ITO and ITO/metal/ITO (IMI) film sensors have the same total thickness of 100 nm, IMI sensors have a sandwich structure of ITO 50 nm/metal 10 nm/ITO 40 nm. The change in the gas sensitivity of the film sensors caused by methanol gas ranging from 100 to 1000 ppm was measured at room temperature. The IAI film sensors showed the higher sensitivity than the other sensors. Finally, it is concluded that the ITO 50/Au 10/ITO 40 nm film sensors hasthe potential to be used as improved methanol gas sensor.
합성제트를 이용한 풍력터빈 에어포일의 유동 제어에 관한 수치적 연구
이학민(H.M. Lee),권오준(O.J. Kwon) 한국전산유체공학회 2017 한국전산유체공학회지 Vol.22 No.3
In the present study, a numerical study about flow control of a wind turbine airfoil was performed using computational fluid dynamics (CFD). Two dimensional unsteady Reynolds-Averaged Navier-Stokes (RANS) solver was used to solve the flow around a wind turbine airfoil. Synthetic jets were applied to the DU 35 airfoil used in the inboard section of the NREL 5MW wind turbine. In order to simulate the synthetic jets, suction/blowing boundary condition was applied. The flow characteristics of synthetic jets were investigated according to the injection speed and injection angle. The injection velocity is 1, 2, and 3 times the freestream and the injection angle is 45 degrees. As the injection speed increases, more energy is transferred into the boundary layer. Therefore, the performance of the DU 35 airfoil is most improved when the injection speed is 3 times the freestream. In the case of the injection angle, the flow analysis was performed at 0 degrees, 45 degrees, and the direction perpendicular to the surface. The injection speed at this time is 3 times. The size and shape of the vortices generated by the synthetic jets depend on the injection angle. When the injection angle is 45 degrees, the performance enhancement of the DU 35 airfoil is the greatest.
Effect of Intermediate Metal on the Methanol Gas Sensitivity of ITO Thin Films
H. M. Lee(이학민),S. B. Heo(허성보),Y. M. Kong(공영민),Daeil Kim(김대일) 한국진공학회(ASCT) 2011 Applied Science and Convergence Technology Vol.20 No.3
RF 마그네트론 스퍼터와 DC 마그네트론 스퍼터를 병행하여 ITO/Au/ITO, ITO/Cu/ITO, 그리고 ITO/Ni/ITO 박막을 유리기판 위에 증착하였다. 증착 후 진공열처리를 통하여 층간 금속 층이 ITO박막의 메탄올 검출 민감도에 미치는 영향을 분석하였다. 모든 박막센서의 두께는 100 ㎚로 동일하게 ITO 50 ㎚/metal 10 ㎚/ITO 40 ㎚로 제작되었고 메탄올 농도는 100에서 1,000 ppm까지 달리하였다. ITO/Au/ITO 박막센서가 가장 높은 민감도를 보임으로써 ITO/Au/ITO 다층박막이 기존의 ITO메탄올 센서를 대체할 수 있는 센서임을 확인하였다. ITO thin films and gold (Au), copper (Cu) and nickel (Ni) intermediate ITO multilayer (ITO/Au/ITO, ITO/Cu/ITO, ITO/Ni/ITO) films were deposited on glass substrates with a reactive radio frequency and direct current magnetron sputtering system and then the effect of intermediate metal layer and annealing temperature on the methanol gas sensitivity of ITO films were investigated. Although both ITO and ITO/metal/ITO (IMI) film sensors have the same total thickness of 100 ㎚, IMI sensors have a sandwich structure of ITO 50 ㎚/metal 10 ㎚/ITO 40 ㎚. The change in the gas sensitivity of the film sensors caused by methanol gas ranging from 100 to 1000 ppm was measured at room temperature. The IAI film sensors showed the higher sensitivity than the other sensors. Finally, it is concluded that the ITO 50/Au 10/ITO 40 ㎚ film sensors hasthe potential to be used as improved methanol gas sensor.
유전 알고리즘과 인공 신경망 기법을 이용한 무인항공기 로터 블레이드 공력 최적설계
이학민(H.M. Lee),유재관(J.K. Ryu),안상준(S.J. Ahn),권오준(O.J. Kwon) 한국전산유체공학회 2014 한국전산유체공학회지 Vol.19 No.3
In the present study, an aerodynamic design optimization of UAV rotor blades was conducted using a genetic algorithm(GA) coupled with computational fluid dynamics(CFD). To reduce computational cost in making databases, a function approximation was applied using artificial neural networks(ANN) based on a radial basis function network. Three dimensional Reynolds-Averaged Navier-Stokes(RANS) solver was used to solve the flow around UAV rotor blades. Design directions were specified to maximize thrust coefficient maintaining torque coefficient and minimize torque coefficient maintaining thrust coefficient. Design variables such as twist angle, thickness and chord length were adopted to perform a planform optimization. As a result of an optimization regarding to maximizing thrust coefficient, thrust coefficient was increased about 4.5% than base configuration. In case of an optimization minimizing torque coefficient, torque coefficient was decreased about 7.4% comparing with base configuration.
유전 알고리즘과 인공 신경망 기법을 이용한 무인항공기 로터 블레이드 공력 최적설계
이학민(H. M. Lee),유재관(J. K. Ryu),안상준(S. J. Ahn),권오준(O. J. Kwon) 한국전산유체공학회 2014 한국전산유체공학회 학술대회논문집 Vol.2014 No.5
In the present study, an aerodynamic design optimization of UAV rotor blades was conducted using a genetic algorithm(GA) coupled with computational fluid dynamics(CFD). To reduce computational cost in making databases, a function approximation was applied using artificial neural networks(ANN) based on a radial basis function network. Three dimensional Reynolds-Averaged Navier-Stokes(RANS) solver was used to solve the flow around UAV rotor blades. Design directions were specified to maximize thrust coefficient maintaining torque coefficient and minimize torque coefficient maintaining thrust coefficient. It adopts design variables such as twist angle, thickness and chord length to perform a planform optimization. As a result of an optimization regarding to maximizing thrust coefficient, thrust coefficient was increased about 4.5% than initial one. In case of an optimization minimizing torque coefficient, torque coefficient was decreased about 7.4% comparing with initial one.