• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.23 no.5
• /
• pp.1319-1324
• /
• 1998

The phase and frequency commands of a ratating radar system that utilizes frequency scanning to steer the beam in the azimuth direction and phase shifters in the elevation direction are derived in terms of the angles of the groung based coordinate system. The antenna type considered is slotted arrays that are easy to construct at such high microwave frequency as the X band. The frequency that has non-linear characteristics as a functio ofthe elevation angle is plotted and the derived frequency equation is aproximated to be a simple form to reduce the calculation time for real time multi-function radar systems. It is shown that the approximated frequency command is in good agreement with the exact one if the range of azimuth scanning is limited by ${\pm}10^{\circ}$.

• Journal of Digital Convergence
• /
• v.18 no.2
• /
• pp.483-487
• /
• 2020

In this study, the effects of suspension training according to the types of ground. Fourteen healthy male college students measured for the characteristics of core muscle activity in suspension training on two different types of grounds, normal flat and unstable ground using a gym ball. EMG (Electromyography) was exploited to measure the activity of the core muscles according to the types of the ground. Muscle activity of the abdominal muscles, external oblique muscles, internal oblique muscles, and lower lumbar standing muscles was measured. The variables in analyses were measured by the means of % MVC method to standardize the EMG signal according to the ground type for each core muscle. In order to verify the differences in core muscles according to the type of ground the paired t-tests were performed at the significance level of 0.05 (p<.05). As a result of measuring the activity of the core muscles according to the various types of grounds, the difference between muscle characteristics obtained in two different grounds did not appear to be statistically significant. However, the result is an important clue to reconsider the notion that the training effect on the unstable ground is generally superior to the effect on the stable ground in the core muscle training. The type of ground in the core muscle training has been found not to significantly affect the muscle activation according to the results of this study. Regardless of the type of exercise program, hence, the difference in muscle activation will not be insignificant even with the standardized program strengthening core muscles.

• Korean Journal of Applied Biomechanics
• /
• v.18 no.3
• /
• pp.71-82
• /
• 2008

W. S. CHAE, Ground Reaction Force Charateristics During Forward and Backward Walking Over 20 Degree Ramp. Korean Journal of Sport Biomechanics, Vol. 18, No. 3, pp. 71-82, 2008. The purpose of this study was to compare GRF characteristics during forward and backward walking over 20 degree ramp. Temporal parameters, GRFs, displacement of center of pressure (DCP), and loading and decay rates were determined for each trial. The results showed that the vertical GRF in BD during RTO was significantly greater than those found in FU. This reults indicated that GRF patterns may be changed by different walking conditions and altering position of ankle, knee, and center of mass throughout the walking cycle. The DCP during $RHC_2$-LHC in antero-posterior direction for downward was smaller than the corresponding value for upward condition. It' seems that the ankle and knee joints are locked in an awkward fashion at the toe contact to compensate for imbalance. Reducing the magnitude of loading rate can be achieved by walking in the backward direction. Accordingly, the results can be a benefit if one is suffering from an impact-type injury.