113 research outputs found
Burglarproof WEP Protocol on Wireless Infrastructure
With the popularization of wireless network, security issue is more and more important. When IEEE 802.11i draft proposed TKIP, it is expected to improve WEP (Wired Equivalent Privacy) on both active and passive attack methods. Especially in generating and management of secret keys, TKIP uses more deliberative attitude to distribute keys. Besides, it just upgrades software to accomplish these functions without changing hardware equipments. However, implementing TKIP on the exiting equipment, the transmission performance is decreased dramatically. This article presents a new scheme, Burglarproof WEP Protocol (BWP), that encrypt WEP key twice to improve the security drawbacks of original WEP, and have better performance on transmission. The proposed method is focus on modifying encryption sets to improve the low performance of TKIP, and provides better transmission rate without losing security anticipations base on current hardware configuration
THE STUDY OF THE AREA OF FOOTPATH BETWEEN MALE AND FEMALE ELITE DISTANT RUNNERS UNDER DIFFERENT RUNNING SPEEDS OF A TREADMILL
The purpose of this study was to investigate and to compare the difference of area of footpath between male and female elite distant runners under 3 m/s and 4 m/s running speeds on a treadmill. There were 9 male and 7 female subjects jointed this study. AJVC DVL-9800 digital camera was utilized to record subject's running movement, and the Ariel Performance Analysis System was used for digitizing. The t-test statistics was used to test the difference between variables. The results indicated that both male and female runners' areas of footpaths were greater when the running speed was increased, and there was no significant difference between male and female runners
KINETIC ANALYSIS OF LOWER EXTREMITY DURING SIDESTEP CUITING UNDER DIFFERENT DIRECTIONS
The purpose of this study was to investigate the ground reaction forces, joint reaction forces, net muscle joint moments of the ankle, knee and hip during elite lhandball athletes executed typical cutting maneuver under four different directions. Four male elite handball players were tested during fast running (4.5-5.5 m/s) and then performed cutting to the right off (30°, 400 50°, 600 A JVC camera (60 Hz) and synchronized with force plate (1200 Hz) were used to collect the relative parameters of braking leg during cutting maneuver. Each participant's braking leg (right leg) was modeled as a system of rigid bodies. The inverse dynamics approach was used to integrate the body segment parameter, kinetic and force plate data, and to solve the resultant joint moments. The results showed that sidestep cutting maneuver would produce a load and according to the increase of cutting angles, the lower extremity could receive a strike force and moment during the braking phase. Besides, while the knee angle of f1exion was small and repeated loading of this magnitude were enough to produce the fatigue of lower extremity joints that would eventually resu'lt in complete disruption and clinical lower extremity joints injury
EFFECT OF DIFFERENT RUNNING SPEED ON VERTICAL OSCILLATION AND STRIDE
The main purpose of this study was to investigate the effect of different running speed (3.5±O.3 and 4.9±O.2 m/si on vertical oscillation of the center of gravity and stride. Ten male elite running players served as subjects. A camera (60Hz) was to collect the parameters during running. From this research, the t-Test is used to analyze the parameters of the kinematics in different running speed. Results indicated that different running speed would not affect the vertical oscillation of human body center of gravity. In addition, a significant difference (p< .05) was found in the same speed of different step, but no significance was found in different running speed of the same step. The duration of the stance phase in lower speed for about 38.34% of the stride and the swing phase for 61.66%, in higher speed for about 32.11 % and 67.89%
KINEMATIC ANALYSIS OF LOWER EXTREMITY ON DIFFERENT RUNNING SPEED
A kinematic analysis of selected variables of human lower extremity was completed during different running speed (3.5±O.3 and 4.9±O.2 m/s)on treadmill.Ten male elite running players served as subjects.It got two dimensions photograph analysis along sagittal plane with video data collected at 60Hz.The purpose of the study was to analyze the kinematic parameters including the range of motion,the joint angle,angular velocity and angular acceleration of lower extremity joint related to the cycle time during horizontal running. According to the experimental result of a research ,we could get the below conclusion:angle of lower-extremityed joints in different running speed reaches significant difference. Angle of lower-extremityed joints is getting more with the increasing of velocity.Then maximum angle, angular velocity and angular acceleration of knee joints stretched are getting more with the increasing of velocity. Maximum stretched angle in joint extension phase of take-off significnce
THE ANALYSIS OF ANGULAR MOMENTUM OF SIDE-VOLLEY SOCCER SHOTS PERFORMED AT THREE BALL-HEIGHT
The purpose of this study was to examine side-volley soccer shots performed at three ballheight.
Five amateur, right leg dominant, male soccer players (height = 173 ±2.86 cm; weight = 68 ±6.04 kg; age = 20.5 ±0.5 yrs) participated in this study. Two electrically synchronized highspeed
video cameras (Redlake) were used to sample the kicking motion at 250 Hz. By the three-dimensional cinematographic technical analysis, the kicking leg was modeled as a threelink
kinetic chain composed of thigh, shank, and foot, from which angular velocities and angular momentum were computed. Significantly greater ball velocity and foot velocity were achieved in kicking lower ball-height, with a shorter leg-swing time. The foot moment of inertia exhibited a high value in side-volley shot performed at the lower ball-height. These results indicated that the side-volley soccer shots performed at the lower ball-height would made higher value of foot angular momentum, and benefited ball velocity
ANALYSIS OF ANGULAR MOMENTUM THE WHOLE BODY DURING GLIDE HITTING AND KICK HITTING IN BASEBALL
The purpose of this study were to analyze the biomechanical characteristics of glide and kick hitting in baseball which exerted by professional baseball players in Taiwan. Five professional baseball players were selected as the subjects. The experiment used two JVC-DV 9800 high-speed digital cameras(120 Hz).The video data was treated by Kwon3D 3.0 motion analysis system. The following are the main results: The kick hitting could get better rotation benefit and optimum. In the stride phase, angUlar momentum of the body is increasing by body inertia. In the rotation phase, the velocity increasing of the body center of gravity makes the angUlar momentum increase. The largest angular momentum appears right before the ball hi!. Because the body inertia in ball hitting moment was very small, the angUlar momentum was mainly affected by angular velocity. In the phase, the average value, largest value and hitting moment value of angular momentum with kick hitting are larger than those with glide hitting. Therefore, the kick hitting could get larger linear and angular momentum
THE STUDY OF TEAM RESULTANT FORCE VANISHING PERCENTAGE IN ELITE TUG OF WAR PLAYERS
This study was to analyze the factor of team pulling force vanishing percentage between groups with different numbers players and the largest pUlling force with unsteady motion in tug of war after sitting posture between players. The motion of nine female senior high school players(age =16.9 ± 0.6 years, height =163.8 ± 2.7 cm, mass =58.7 ± 4.3 kg) in tug of war was synchronized with a high-speed camera(JVC9800, 60 Hz)and a tensile (TEDEA, 900 Hz). The pulling force was gained by DASYlab6.0. The variance of the angle between the rope and ground was analyzed by Silicon Coach from the film, consisted by two to eight players. Results: The team pUlling resultant was smaller than the sum of individual players. The vanishing percentage of pulling force was increase with the number of players. The factor of force vanishing was the coordination between players. The larger numbers players are, the 'lower coordination was. This is so called Ringlemann effect; the factor was timing of the maximal pulling force with each player, therefore coordination was decreasing with the numbers of players, so was force
EFFECT OF BACKPACK ON SELECTED GAIT PARAMETERS OF PRIMARY SCHOOL CHilDREN
The purpose of this study was to compare the effects of a backpack load of 15% body weight (BW) on selected gait parameters of primary school children. Ten participants were recruited from primary school (age: 10.3 ± 0.48 yrs; hI: 141.3 ± 0 .41 cm; mass:
38.1 ± 6.1 kg). A JVC 9800 (60 hz) video camera synchronized with an AMTI force plate (1200 Hz) were used to collect data. A repeated measure t-test (p < 0.05) was used for group comparisons. The backpack load did not affect either the proportionate time of the stance phase, swing phase, or the magnitude of selected vertical and anterioposterior ground reaction force parameters. However, the 15% backpack load did cause a significant increase in proportionate double leg support time
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