• 한국운동역학회지
• /
• 제30권3호
• /
• pp.225-234
• /
• 2020

Objective: The purpose of this study was to investigate the kinematic sequence patterns according to movement times during Karate choku-tsuki. Method: Ten Korea national Karate athletes participated in this study. Participants asked to perform jodan and chudan choku-tsuki. 30 infrared cameras were used to measure angular kinematic of elbow, shoulder, trunk, pelvis, hip, knee, ankle. Results: The two-way repeated measures ANOVA revealed significant effects for the joints (p<.05). But no significant effect for the movement time and interaction of joints x movement time existed for the kinematic sequence variables. Conclusion: For karate kumite players to reduce the movement time of punch, it is necessary to train kinematic sequences that allow each joint to rotate at a relatively similar timing.

• 한국자동차공학회논문집
• /
• 제5권1호
• /
• pp.38-48
• /
• 1997

A method for performing kinematic design sensitivity analysis of vehicle suspension systems is presented. For modeling of vehicle suspensions, the multibody dynamic formulation is adopted, where suspensions are assumed as combination of rigid bodies and ideal frictionless joints. In a relative joint coordinate setting, kinematic constraint equations are obtained by imposing cut-joints that transform closed-loop shape suspension systems into open-loop systems. By directly differentiating the constraint equations with respect to kinematic design variables, such as length of bodies, notion axis, etc., sensitivity equations are derived. By solving the sensitivity equations, sensitivity of static design factors that can be used for design improvement, can be obtained. The validity and usefulness of the method are demonstrated through an example where kinematic sensitivity analysis of a MacPherson strut suspension of performed.

• 제어로봇시스템학회논문지
• /
• 제18권9호
• /
• pp.823-829
• /
• 2012

An excitation table is commonly used for vibration and ride tests for parts or assemblies of automobiles, aircrafts, or other heavy systems. The authors have analyzed several kinematic properties of an excitation table that is under development for heavy transport vehicles. It consists of one table and 7 linear hydraulic actuators. The authors have performed mobility analysis, inverse kinematics, forward kinematics, and singularity analysis. Especially, we have proposed a fast forward kinematic solution considering the limited motion of the excitation table. On the assumption that the motion variables such as rotation angles and displacements are small, the forward kinematic problem is converted to the observer problem of a linear system. This provides a fast solution. Also we have verified that there are no singularity points in the working range by numerical analysis.

• 대한기계학회논문집
• /
• 제18권2호
• /
• pp.351-358
• /
• 1994

A probabilistic model and analysis methods to determine the means and variances of the velocity and acceleration in stochastically-defined planar pin jointed kinematic chains are presented. The presented model considers the effect of tolerances on link length and radial clearance and uncertainty of pin location as a net effect on the link's effective length. The determination of the mean values and variances of the output variables requires the calculation of sensitivities of secondary variables with respect to the random variables. It is shown that this computation is straightforward and can be accomplished by a conventional kinematic analysis package with minor modification. Thus, the concepts of tolerance and clearance have been captured by the model and analysis. The only input data are the nominal linkage model and statistical information. The "effective link length" model is shown to be applicable to both analytical solution and Monte Carlo simulation. The results from both methods are compared. This paper Ksolves the higher-order kinematic problems for the probabilistic design analysis of stochastically-defined mechanisms.echanisms.

• International Journal of Automotive Technology
• /
• 제6권3호
• /
• pp.235-242
• /
• 2005

This study introduces the Reliability-Based Design Optimization (RBDO) to enhance the kinematic and compliance (K & C) characteristics of automotive suspension system. In previous studies, the deterministic optimization has been performed to enhance the K & C characteristics. Unfortunately, uncertainties in the real world have not been considered in the deterministic optimization. In the design of suspension system, design variables with the uncertainties, such as the bushing stiffness, have a great influence on the variation of the suspension performances. There is a need to quantify these uncertainties and to apply the RBDO to obtain the design, satisfying the target reliability level. In this research, design variables including uncertainties are dealt as random variables and reliability of the suspension performances, which are related the K & C characteristics, are quantified and the RBDO is performed. The RBD-optimum is compared with the deterministic optimum to verify the enhancement in reliability. Thus, the reliability of the suspension performances is estimated and the RBD-optimum, satisfying the target reliability level, is determined.

• 한국운동역학회지
• /
• 제13권1호
• /
• pp.155-171
• /
• 2003

The purpose of this study was to analyze the kinematic variables of over head kick(OHK) in soccer with three dimensional analysis technique and show the kinematic characteristics of it. The 7 subjects were university football player who have been playing football more than 7 years. The OHK was filmed on 16mm video camera(30frame/sec.) kinematic variables were temporal, postures, and COG(center of gravity). The mean values and the standard deviation for each variables were obtained and used as basic factors for examining characteristics of OHK. The results of this analysis were as follows : Temporal variables : The total time elapsed(TE) of OHK was $0.95{\sim}1.14sec$, the 1st phase was 0.35sec., 2nd phase was 0.46sec., and 3rd phase was 0.22sec.. Posture variables : When subjects performed OHK at the impact event, the ankle and knee angle of kicking foot were more extend than supporting foot. but the hip angle of supporting foot were more extend than kirking foot. Moving distance of the center of mass of the both foot. When subject performed OHK at the impact event, the range of distance on mediolateral direction aspect into right left shoulder line, anteroposterior direction aspect was $20.9{\pm}10.5cm$, vertical direction aspect was $92.3{\pm}19.9cm$. Angular velocity : the faster angular velocity of knee ankle on the kicking foot pew form jump position to landing position, the faster velocity of ball became. C. O. G. variables. When subject performed OHK at the impact event, upper part of the body was getting lower, lower part of the body was getting higher.

• 한국운동역학회지
• /
• 제17권4호
• /
• pp.157-167
• /
• 2007

The purpose of this study was to analyze kinematic techniques in the woman's 100m hurdle. In order to find the kinematic parameters, a 3-D video system for kinematic analysis-kwon3d 3.1(Kwon3D Motion Analysis Program Version 3.1)-was used. Eight JVC video cameras(GR-HD1KR) were used to film the performance of Lee Yeon-Kyoung at a frame rate of 60fields/s. The kinematic characteristics from the first hurdle to last hurdle were analyzed at the clearing hurdle spots such as distance, velocities, heights and angles. The real-life three-dimensional coordinates of 20 body landmarks during each phases were collected using a Direct Linear Transformation procedure. After analyzing the kinematic variables in the 100m hurdle run, the following conclusion were obtained; Lee Yeon-Kyoung had to maintain constant stride lengths between hurdles and increase takeoff distance before clearance and shorter landing distance after clearance. She also had to hit the correct takeoff point in front of the hurdle and extend the lead leg at the moment of landing in order to minimize the loss of velocity. She had to sprint between hurdles as fast as possible over 8m/s and run powerful first stride and shortened third stride preparing for the following hurdle clearances.

• 한국운동역학회지
• /
• 제26권3호
• /
• pp.273-284
• /
• 2016

Objective: The purpose of this study was to investigate effects of upper limb, trunk, and pelvis kinematic variables on the velocity of Apkubi Momtong Baro Jireugi in Taekwondo. Method: Twenty Taekwondo Poomsae athletes (age: $20.8{\pm}2.2years$, height: $171.5{\pm}7.0cm$, body weight: $66.2{\pm}8.0kg$) participated in this study. The variables were upper limb velocity and acceleration; trunk angle, angular velocity, and angular acceleration; pelvis angle, angular velocity, and angular acceleration; and waist angle, angular velocity, and angular acceleration. Pearson's correlation coefficient was calculated for Jireugi velocity and kinematic variables; multiple regression analysis was performed to investigate influence on Jireugi velocity. Results: Angular trunk acceleration and linear upper arm punching acceleration had significant effects on Jireugi velocity (p<.05). Conclusion: We affirmed that angular trunk acceleration and linear upper arm punching acceleration increase the Jireugi velocity.

• 한국운동역학회지
• /
• 제22권4호
• /
• pp.395-404
• /
• 2012

This study was to perform the kinetic analysis of tucked backward salto on the balance beam. Eight women's gymnastics players(age: $15.88{\pm}2.45yrs$, career: $6.38{\pm}0.52yrs$, height: $152.38{\pm}7.35cm$, weight: $44.25{\pm}7.54kg$) of the I-region participated in this study. The kinematic variables were analyzed response time of motion, angle, velocity, acceleration and the kinetic variables were analyzed ground reaction force(GRF) of motion. For measure and analysis of kinematic and kinetic variables of this study, used to synchronized to 6 Eagle camera and 1 force plate, used to the Cortex(Ver. 1.0) for analyzed of variables. The results were as follows; To the kinematic variables of tucked backward salto on the balance beam, a time appeared longer landing than air rotation, changes of angle regulated segment of body smaller moment of inertia when air rotation, larger moment of inertia when releasing and landing. A velocity appeared fast motion when releasing and air rotation of body, but appeared more decelerations from landing and acceleration showed to be tended to velocity. A GRF appears jump more than twice the weight at the moment that showed the power of motion to all subject.

• 한국운동역학회지
• /
• 제13권2호
• /
• pp.65-74
• /
• 2003

The purpose of this study was to analyze kinematic variables in the badminton smash motion through 3-dimensional image analysis. The kinematic variables were velocity of joints in upper limbs, the angle of wrist in the impact, and the angular velocity of the top of racket head. The smash motions of four male badminton players in H University and four male students at department of the physical education in K University who were not majoring in badminton were analyzed kinematically and the attained conclusions were as follow. 1. The velocity of segments in upper limbs of the unskilled group was faster than that of the skilled group. The movement pattern was fast back swing-slow impact moment-fast fellow through in the unskilled group, but slow back swing-fast impact moment-slow follow through in the sullied group. 2. As the BS phases, the velocity of segment in right shoulder was different significantly between groups. Right elbow and right wrist segments, velocity of racket head was different significantly between groups(p<.05) by IP phases. As the FT phases, there was no significant difference. 3. The angle of right wrist at the impact, the angle of palm flexion and the angle of palm flexion in aspect were shown that the skilled group was higher than unskilled group. There was no significant difference. 4. The velocity of racket head was shown that the unskilled group has fast velocity, but the angle velocity was shown the unskilled group has slow. 5. The angle velocity of racket head in aspect were no significant difference between groups, but maximal angle velocity was different significantly between groups(p<.05).