• Korean Journal of Applied Biomechanics
• /
• v.13 no.2
• /
• pp.75-87
• /
• 2003

The purpose of this study was to identify the mechanical factors that are crucial to the successful double salto backward piked dismount on the parallel bars. The subjects were 5 national gymnasts(G1: sucessed landing, G2: failed landing), two video cameras were used to record the dismount of the subjects. It summarizes that (a) It is important to make small slope angle(X axis, Y axis) at release, whereas it makes large shoulder angle and trunk rotation angle. (b) It is important to prepare landing in advance, reducing vertical velocity and making large hip angle at BTO(body take off). (c) It is also important to make small knee angle and hip angle, and reduce the angle of trunk rotation.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.19 no.3
• /
• pp.235-252
• /
• 2015

Optimal impact angle control guidance law and its variants for intercepting a maneuvering target are introduced in this paper. The linear quadratic(LQ) optimal control theory is reviewed first to setup framework of guidance law derivation, called the sweep method. As an example, the inversely weighted time-to-go energy optimal control problem to obtain the optimal impact angle control guidance law for a fixed target is solved via the sweep method. Since this optimal guidance law is not applicable for a moving target due to the angle mismatch at the impact instant, the law is modified to three different biased proportional navigation(PN) laws: the flight path angle control law, the line-of-sight(LOS) angle control law, and the relative flight path angle control law. Effectiveness of the guidance laws are verified via numerical simulations.

• Journal of the Semiconductor & Display Technology
• /
• v.18 no.2
• /
• pp.87-91
• /
• 2019

In this paper, we have development of horizontal attitude monitoring system for agricultural robots. A two-axis gyro sensor and a two-axis accelerometer sensor are used to measure the horizontal attitude angle. The roll angle and pitch angle were measured through the fusion of the gyro sensor signal and the acceleration sensor signal for the horizontal attitude monitoring of the robot. This attitude monitoring system includes GPS and Bluetooth communication module for remote monitoring. The roll angle and pitch angle can be measured by the error of less than 1 degree and the linearity and the reproducibility of the output signal are excellent.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.68 no.4
• /
• pp.566-572
• /
• 2019

This paper proposes a new composite guidance law that can intercept moving targets and satisfy look angle rate constraint. In order to obtain the composite guidance law, we first develop a new look angle rate control guidance law which can maintain the maximum look angle rate limitation. And then, we propose the composite guidance scheme on the basis of the look angle rate control guidance and the proportional navigation guidance. To investigate the capturablity and characteristics of the proposed guidance, we also derive closed-form solutions and perform various numerical simulations. The proposed composite guidance only requires the line-of-sight rate, closing velocity, and missile's speed, thereby easily implementing in practical homing missiles.

• Journal of the Korean Society of Visualization
• /
• v.19 no.3
• /
• pp.22-30
• /
• 2021

Ventilated cavity shapes by varying angle of attack of a circular cavitator were predicted based on Logvinovich's Independence Principle in order to verify the cavity shape prediction method. The prediction results were compared with model experiments conducted in the high-speed cavitation tunnel. In the prediction of the cavity centerline, the movement of the cavity centerline due to the effect of gravity and cavitator's angle of attack were well predicted. In the prediction of the cavity contour, it was found that the cavity edge prediction error increased as the angle of attack increased. The error of the upper cavity contour was small at the positive angle of attack, and the error of the lower cavity contour was small at the negative angle of attack.

• Journal of the Korean Magnetic Resonance Society
• /
• v.10 no.1
• /
• pp.1-37
• /
• 2006

General expressions for solid state NMR lines are described for transitions under static, magic angle spinning, and variable angle spinning conditions in the case where the principal axis system for the anisotropic chemical shift tensor is noncoincident with that of the quadrupole coupling tensor. It is demonstrated that solid state NMR powder pattern simulation program VMAS based on the conventional grid point method of integrating over the Euler angle space is fast enough in comparison with the POWDER simulation package and Gauss-point method.

• Proceedings of the KIPE Conference
• /
• 1999.07a
• /
• pp.151-154
• /
• 1999

This paper presents a driving method of 3-phase 4-poles SRM(switched reluctance motor) drived by switching angle control. In this study, the switching angle is determined from approximated analysis and computer simulation by using MATLAB for high efficiency according to the speed and torque required by load, and then microcontroller controls the switching angle of asymmetrical inverter in SRM driver. Also, we experiment the maximum forque driving and maximum power driving by controlling switching angle available to electric vehicle.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.872-877
• /
• 2003

The fixed-angle based modified compression field theory (MCFT) was developed to include the slip deformation across the crack, thereby allowing for the non-coincident directions of the principal strain and stress. To investigate the significance of crack modelling on the analysis, a series of tests on beams without transverse reinforcement was predicted by both rotating- and fixed-angle crack models within the frame of the MCFT. The results predicted by the fixed-angle MCFT were comparable to those by the rotating-angle MCFT when the initial crack angle of 45deg. and the related friction law are used.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.37 no.12
• /
• pp.854-861
• /
• 1988

The current source inverter-fed induction motor(CSIM) drive is widely used in industry because of its four quadrant operation, fuseless protection, fuseless protection, and ruggedness. the CSIM drive system, however, has shortcomins such as slow response and dynamic stability to load torque disturbance and reference speed change. Such a disadvantages can be compensated considerably by means of introducing additional angle angle control loop. The angle control method is dependent upon the inverter type. In this paper, simultaneus recovery and commutation inverter(SRCI) which is developed recently is considered.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.232-232
• /
• 2000

switched reluctance motors and drives are increasingly used in industrial applications due to their robust mechanical structure, low inertia and reduction in the rotor losses. As the motor speed increase turn on angle must be advanced to build up phase current. When C-dump converter is applied to switched reluctance motor, the capacitance of dump C has to have proper value. In this paper advance angle for a switched reluctance motor and capacitance of dump C are investigated. Then proper advance angle and the capacitance of dump-C are propose for the industrial low voltage SR motor.