In the past, aviation technology developed from wood to alloys to composite materials. Propellers have also evolved from wood to composite materials for modern small aircraft. In this context, research is needed on a three-blade composite propeller based on the Rotax 912 engine, which is widely used in Korea. In this study, the goal is to select the optimal propeller pitch angle by investigating noise changes according to changes in blade angle and engine 4000RPM of three types of three-blade propellers different from each propeller manufacturer. By comparing the noise of the three types of propellers most commonly used in Korea and suggesting the minimum noise blade angle for each propeller, we aim to help aircraft operators select propellers and resolve noise complaints around airfields.

In this paper, Fly robot with electric power, a kind of Unmanned aerial vehicle (UAV), is considered as an autonomous hovering platform, capable of vertical lift-off, landing and stationary hovering. This aircraft has four rotor and DC motors of electrical Power, which is capable of Omni-direction for indoor application. In the earlier days of vertical flight experimentation developers looked at the intuitively easy control functionality of 4 rotor designs. But we need to obtain design method of suitable structures and adequate components because the existing prototypes of 4 rotor-craft don't analyze the propeller, motor characteristic and propose a methodology to optimize this system. In design of propeller, experimental results show that thrust and power are relatively efficient at a pitch angel of 20 degree. To the conclusion, the design method and optimization method of the propeller, motor, frame, Blimp, which are the main design elements of the blimp type 4 rotor craft, were studied to optimize the existing Blimp 4 rotor craft body design method.

A computational fluid flow analysis of a car has been accomplished to explain the lift characteristics according to the changes of wiper angle and car speed. The present study established the process to get the lift coefficient distribution on the whole range of a wiper operating angle. From the result of the present research, it could be seen that the lift coefficient of a wiper with the lower wiper angle had relatively smaller magnitude. On the other hand, the lift coefficient with the wiper angle near 45° was relatively larger than that with the other wiper angles. The present study also verified the usefulness of the lift coefficient that the lift distributions of various car speeds could be derived from the result of a lift coefficient distribution for only a car speed.

This study was undertaken to investigate changes m curve angle of Chinese cabbage blade during salting at various concentration(10, 15, 20, 25%) of salt to evaluated salting degree by curve angle during salting at 20. Salt concentration of brine, the amount of water elution, salt penetration of the tissue(salt concentration of Chinese cabbage), weight loss and texture were investigated. Correlation relation between the above factors and curve angle were determined. The curve angles by method of holding the edge of the Chinese cabbage blade was measured. The curve angles of the mesophyll were proportional to salting time and salt concentration, but slope of line equation showed higher than that of mid-rib. The ideal method of salting evaluation by curve angle was MCA-MRC (the measuring curve angle of mid-rib C) at each concentration of salt. The results of curve angle when reached 3% salt of Chinese cabbage tissue calculated by MCA-MRC at 10, 15, 20 and 25% salting were 57, 43, 36, and 33, respectively. And salting times calculated by the same conditions were 19, 12.5, 9.1 and 4.4hours, respectively.