• Korean Journal of Applied Biomechanics
• /
• v.23 no.4
• /
• pp.387-393
• /
• 2013

The purpose of this study was to investigate the difference of kinematic factors acting in the body during a normal swing and a swing taken with an intention to increase driving distance by female pro golfers. Female pro golfers may increase driver clubhead speed and improve driving distance through maintaining a large X-factor angle during backswing and delaying the uncocking period by rapidly shifting the weight to the left foot during downswing.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.6 no.3
• /
• pp.652-669
• /
• 2014

This paper concerns the kinematic characteristics of a coupling device in a deep-seabed mining system. This coupling device connects the buffer system and the flexible pipe. The motion of the buffer system, flexible pipe and mining robot are affected by the coupling device. So the coupling device should be considered as a major factor when this device is designed. Therefore, we find a stable kinematic device, and apply it to the design coupling device through this study. The kinematic characteristics of the coupling device are analyzed by multi-body dynamics simulation method, and finite element method. The dynamic analysis model was built in the commercial software DAFUL. The Fluid Structure Interaction (FSI) method is applied to build the deep-seabed environment. Hydrodynamic force and moment are applied in the dynamic model for the FSI method. The loads and deformation of flexible pipe are estimated for analysis results of the kinematic characteristics.

• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.12
• /
• pp.157-164
• /
• 1995

Straight belvel gear is used mainly for steering system, final reduction and differential gear in the automobile. The more high load, high velocity driving bevel gear, the more unsafe and unpleasant. In thid study, we get a kinematic equation by modelling straight bevel gear pair with simple elastic system, the dynamic characteristic analysis about this system, we got the dynamic load factor of tooth surface. Comparing the value of dynamic load factor by calculation with the measured value of Terauchi's experimental results is similar. We think it useful to analysis the vibration and the noise of straight bevel gear in operation with the analytic method of dynamic load of straight bevel gear using in this study.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2003.04a
• /
• pp.105-109
• /
• 2003

The occurrence of cycle slips is a major limiting factor to attain high precision positioning and navigation results with GPS. Cycle slips must be correctly repaired at the data processing stage. In this study, the technique to find cycle slips in the processing of data collected with Trimble 4700 GPS receivers is suggested. The use of Kalman filtering techniques is used in an attempt to reduce the effect of the noise in the different quantities involved and to improve the accuracy in cycle slip correction.

• Korean Journal of Applied Biomechanics
• /
• v.25 no.1
• /
• pp.11-19
• /
• 2015

Objective : The purpose of this study was to analyze the correlation between physical factors (X-factor, X-factor stretch) and club factors (club speed, ball speed, club path, smash factor, vertical launch angle, spin rate, flight time, total length) during impact and it affect on the total distance of the ball during a golf driver swing. Background : There were not enough studies that analyzed the correlation between physical factors(X-factor, X-factor stretch) and club factors(club speed, ball speed, club path, smash factor, launch angle, spin rate, flight time, total length) during a purpose swing to increase total distance. Method : For this study, 9 right handed professional male golfers (KPGA) were chosen. The test subject group used their own drivers and each took a total of 10 swings. These swings consisted of 5 purpose swings to increase total distance and 5 normal swings. Results : The purpose swing to increase total distance showed larger physical factors(X-factor, X-factor stretch) compared to a normal swing however the results were not statistically significant. Total distance increased during a purpose swing as a result of ball and club speed. Conclusion : The results showed that club factors, ball speed and club speed contributed the most in affecting the total distance of the ball during a purpose swing.

• Korean Journal of Applied Biomechanics
• /
• v.12 no.2
• /
• pp.381-392
• /
• 2002

This study attempted to indentify changeability of the factorial structure of kinematic analysis in bowling. Subjects of group composed of three groups : Higher bowers who are national representative bowers with 200 average point and one pro-bowler. Middle bowlers who are three common persons with 170 average points. Lower bowler who are three common persons with 150 average points. Motion analysis on throw motion in three groups respectively has been made through three-dimension cinematography using DLT method. Two high-speed video camera at operating 180 and 60 frame per secondary. T-test factorial structure analysis has been used to define variable relations. It was concluded that : 1. The difference of x1, x2, x4, x8, x9, x11, x12, x13 where significant between two group. 2. The difference of number of spin and angle of the back-hand where statistically significant between two group(p<.001, p<.05) 3. The correlation over r=.5 between the kinematic data x1, x2, x3, x9, x10, x11. In the rotation loading matrix Factor 1 was x1, x2, x9, x10 and Factor 2 relates to x3, x11. 4. In order to obtain the factor score as follow as ; Factor 1 = (0.248)X1 + (0.265)X2 + (-0.074)X3 + (0.259)X9 + (0.259)X10 + (-0.025)X11 Factor 2=(-0.016)X1 + (-0.055)X2 + (0.84)X3 + (-0.013)X9 + (-0.007)X10 + (0.553)X11.

• Particle and aerosol research
• /
• v.9 no.4
• /
• pp.271-277
• /
• 2013

This article reports the drag reduction phenomenon of aqueous suspensions containing carbon nanotubes (CNTs) flowing through horizontal tubes. Stable nanofluids were prepared by using a surfactant. It is found that the drag forces of CNT nanofluids were reduced at specific flow conditions compared to the base fluid. It is found that the friction factor of CNT nanofluids was reduced up to approximately 30 % by using CNT nanofluids. Increased kinematic viscosities of CNT nanofluids are suggested to the key factors that cause the drag reduction phenomenon. In addition, transition from laminar to turbulent flow is observed to be delayed when CNT nanofluids flow in a horizontal tube, meaning that drag reduction occurs at higher flow rates, that is, at higher Reynolds numbers.

• Journal of Mechanical Science and Technology
• /
• v.17 no.4
• /
• pp.477-483
• /
• 2003

An independent kinematic hardening material model in which the reverse yielding point is defined by the Bauschinger effect factor (BEF) , has been defined for stainless steel SUS 304. The material model and the BEF are obtained experimentally and represented mathematically as continuous functions of effective plastic strain. The material model has been incorporated in a non-linear stress analysis for the prediction of reverse yielding in thick-walled cylinders during the autofrettage process of these vessels. Residual stress distributions of the independent kinematic hardening material model at the onset of reverse yielding are compared with residual stresses of an isotropic hardening model showing the significant effect of the BEF on reverse yielding predictions. Critical pressures of direct and reverse yielding are obtained for the most commonly used cylinders and a range of permissible internal pressures for an efficient autofrettaged process is recommended.

• Structural Engineering and Mechanics
• /
• v.71 no.3
• /
• pp.245-255
• /
• 2019

In this paper, an inverted-pendulum model consisting of a point supported by spring limbs with roller feet is adopted to simulate human walking load. To establish the kinematic motion of first and second single and double support phases, the Lagrangian variation method was used. Given a set of model parameters, desired walking speed and initial states, the Newmark-${\beta}$ method was used to solve the above kinematic motion for studying the effects of roller radius, stiffness, impact angle, walking speed, and step length on the ground reaction force, energy transfer, and height of center of mass transfer. The numerical simulation results show that the inverted-pendulum model for walking is conservative as there is no change in total energy and the duration time of double support phase is 50-70% of total time. Based on the numerical analysis, a dynamic load factor ${\alpha}_{wi}$ is proposed for the traditional walking load model.

• Korean Journal of Applied Biomechanics
• /
• v.15 no.4
• /
• pp.75-83
• /
• 2005

The purpose of this study was to determine the kinematic characteristics of the ankle joint and RPM(repetition per minutes) during the supra maximal training in cycling. For this study, 8 national representative cyclists, distance cyclists in track and road, were selected. During the super-maximum pedalling, kinematic data were collected using a six-camera(240Hz) Qualisys system. the room coordinate system was right-handed and fixed in the back of a roller for cycle, with right-handed orthogonal segment coordinate systems defined for the leg and foot. Lateral kinematic data were recorded at least for 3 minutes while the participants pedal on a roller. Two-dimensional Cartesian coordinates for each marker were determined at the time of recording using a nonlinear transformation technique. Coordinate data were low-pass filtered using a fourth-order Butterworth recursive filter with cutoff frequency of 15Hz. Variables analyzed in this study were compared using a one factor(time) ANOVA with repeated measures. The results of investigation suggest that the number of rotating pedal was decreased with time phase during the super-maximum pedaling. Maximum angle of the ankle joint showed little in change with time phase compared with minimum angle of that.