• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.16 no.11
• /
• pp.1008-1013
• /
• 2003

We have studied the effect of black matrix (BM) according to the dielectric anisotropy of liquid crystals (LCs) for a homogeneously aligned LC cell driven by fringe-electric field. The results show that for a LC with positive dielectric anisotropy (+LC) there is a large transmittance change when using a conductive BM, whereas the transmittance change is low for a LC with negative dielectric anisotropy (-LC). The conductive BM existing on top substrate produces vertical electric field, which makes the LC molecules be tilt upward from the substrate and have small twist angle for the +LC. However, for the -LC the conductive BM affects the LC distribution only slightly due to characteristic of the -LC orienting perpendicular to the field. Therefore, for the +LC the electro-optic characteristics are strongly dependent on conductivity of the BM on top substrate in a homogeneous liquid crystal cell driven by fringe-electric field.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.10
• /
• pp.955-965
• /
• 2010

The MH-75 propeller for the MAV propulsion is designed using a free vortex design method which considers design parameters such as the hub-tip ratio, the twist angle distribution, the maximum camber location and the chord length of the propeller blade. Aerodynamic characteristics of the MH-75 propeller are predicted by changing the flight speed using the frequency domain panel method. And, the thrust characteristics of the MH-75 propeller are measured using the balance system of the subsonic wind tunnel for the validation of numerical results. The performance characteristics of the MH-75 propeller satisfied with design requirements. Numerical results of the MH-75, which are predicted by the frequency domain panel method, are more agree with experimental results compare with XFOIL.