• Korean Journal of Applied Biomechanics
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• v.18 no.1
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• pp.227-234
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• 2008

The purpose of this study was to investigate kinematic factors affecting scores of Olympic Round Game during follow through which was basic and important in archery. For this study, 8 male archers($20{\pm}1\;yrs$, $77{\pm}13kg$, $178{\pm}5\;cm$) of K university participated in the experiment. The seven infrared cameras (Qualisys MCU-240) were used to acquire raw data, and analyzed with Matlab6.5 for variables. The results were as follows: First, angular average velocity of shoulder joint affecting scores was a statistical significance (p=.65, p<.10), and the regression equation was y = - 0.0637 x + 17.074, and determinant coefficient $R^2$ = 0.874 respectively. Second, good records was acquired about $120^{\circ}$/sec. of angular average velocity of shoulder joint. Third, as records was lower and lower, a peak-pulse on angular average velocity of shoulder joint was great during follow through. In conclusion, the record was greater as angular average velocity of shoulder joint was smaller and smaller from $110^{\circ}$/sec. to $160^{\circ}$/sec. It is suggested that a lower angular average velocity of shoulder joint and no peak-pulse may obtain good scores during follow through.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.4
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• pp.65-73
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• 2003

This paper presents the implementation of an analog signal-processing ASIS to detect an angular velocity signal from a vibrator angular velocity detection sensor. The output of the sensor to be charge appeared as the variation of the capacitance value in the structure of the sensor was detected using charge amplifiers and a self oscillation circuit for driving the sensor was implemented with a sinusoidal self oscillation circuit using the resonance characteristics of the sensor. Specially an automatic gain control circuit was utilized to prevent the deterioration of self-oscillation characteristics due to the external elements such as the characteristic variation of the sensor process and the temperature variation. The angular velocity signal, amplitude-mod)Hated in the operation characteristics of the sensor, was demodulated using a synchronous detection circuit. A switching multiplication circuit was used in the synchronous detection circuit to prevent the magnitude variation of detected signal caused by the amplitude variation of the carrier signal. The ASIC was designed and implemented using 0.5${\mu}{\textrm}{m}$ CMOS process. The chip size was 1.2mm x 1mm. In the experiment under the supply voltage of 3V, the ASIC consumed the supply current of 3.6mA and noise spectrum density from dc to 50Hz was in the range of -95 dBrms/√Hz and -100 dBrms/√Hz when the ASIC, coupled with the sensor, was in normal operation.

• Korean Journal of Applied Biomechanics
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• v.17 no.1
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• pp.191-199
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• 2007

This study was conducted to examine the biomechanical characteristics of open spike in the volleyball to improve the technique of the volleyball spike. The subjects were six male college and high school athletes. The motions of volleyball spike were filmed by using two Sony VX 2000 Video Cameras. The mechanical factors were angle and angular velocity of body segments in the upper and the lower limbs. The conclusions were as follows; 1. The angle of the shoulder joint of the skilled showed larger than that of the unskilled in impacting of the volley ball spike. 2. The angle of the elbow joint of the skilled showed larger than that of the unskilled in impacting of the volley ball spike. 3. The angle of the wrist joint of the skilled showed smaller than that of the unskilled in impacting of the volley ball spike. 4. The angle of the hip joint of skilled showed larger than that of unskilled in impacting of the volley ball spike. 5. The angle of the knee joint of the skilled and the unskilled showed same in take off and impacting of the volley ball spike, and that of the skilled showed smaller than that of the unskilled in take-off touchdown and touchdown after impact of the volley ball spike. 6. The angle of the ankle joint of skilled showed larger than unskilled in take-off of the volley ball spike. 7. The angular velocity of the shoulder joint, elbow joint, wrist joint of the skilled showed faster than that of the unskilled in impacting of the volley ball spike. Taken together the result of them, I have come to conclusion that knee joint angle in touchdown of the take off should be decreased and knee joint angle in take off should be increased, and then stability of the take off should be made and, and that extension of the elbow joint should be made and wrist joint angle decreased and shoulder and hip joint angle increased, and then C.O.G of the arm and hand should be positioned ahead C.O.G of the body in impacting for effective impact of the spike, and that the transfer of the angular velocity of body segments for effective impact of the spike make from the proximal segment to the distal segment at spike in volleyball.

• Korean Journal of Applied Biomechanics
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• v.16 no.4
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• pp.21-30
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• 2006

The purpose of the study is to search for the possibility of the application of kinematics analysis to physical education at schools and expand its scope of application. This study chose 9 college students majoring in physical education and classified them into type A group who can make the straight, vertical handstand, type B group whose waist is bent, type C group who cannot handstand completely. The center of mass, distance between hand and leg, and the angle and angular velocity of each joint were obtained. The result of this study is this. 1. The time for CM showed 6:4 for A group and 5:5 for B and C groups. The distance between hand and foot in the event 3 was 44% of the height for A group, and 41% for B and C groups. A Group showed the higher CM positional significant difference, it was vertically direction below the hip joint at front. For significant difference of the B Group showed horizontal and vertical velocity of the CM, the highest vertical was obtained in phase 3. The difference of angle of shoulder join in the flexion/extension was showed gradually extension event 2 and the height angular velocity was at phase 3 in the A group. 2 The analysis of the handstand motion revealed that the phase 3, but the maintenance of posture start part the handstand is also very important. Through these results, this study confirmed that the time for phase of the CM, horizontal and vertical positions, velocity, the distance between hands and foot, and the difference of the angle and angular velocity of hip joint and shoulder joint can be set as the variables of analysis. It was also definite cause that the handstand motions of college students majoring in physical education had many difference in performance.

• Korean Journal of Applied Biomechanics
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• v.16 no.4
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• pp.49-59
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• 2006

The purpose of this study was to investigate the relations between the segments of the body, the three dimensional anatomical angle according to sweep shot in ice hockey. The subjects of this study were five professional ice hockey players. The reflective makers were attached on anatomical boundary line of body. For the movement analysis three dimensional cinematographical method(APAS) was used and for the calculation of the kinematic variables a self developed program was used with the LabVIEW 6.1 graphical programming(Johnson, 1999) program. By using Eular's equations the three dimensional anatomical Cardan angles of the joint and ice hockey stick were defined. 1. In three dimensional linear velocity of blade the Y axis showed maximum linear velocity almost impact, the X axis(horizontal direction) and the Z axis(vertical direction) maximum linear velocity of blade did not show at impact but after impact this will resulted influence upon hitting puck. 2. The resultant linear velocity of each segment of right arm showed maximum resultant linear velocity at impact. It could be suggest that the right arm swing patterns is kind of push-like movement. therefore the upper arm is the most important role in the right arm swing. 3. The three dimensional anatomical angular displacement of trunk in flexion-extension showed flexion all around the wrist shot. The angular displacement of trunk in internal-external rotation showed internal rotation angle at the backswing top and and increased the angle after the impact. while there is no significant adduction-abduction. 4. The three dimensional anatomical angular displacement of trunk showed most important role in wrist shot. and is follwed by shoulder joints, in addition the movement of elbow/wrist joints showed least to the shot. this study result showed upperlimb of left is more important role than upperlimb of right.

• Korean Journal of Applied Biomechanics
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• v.22 no.1
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• pp.43-53
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• 2012

The purpose of this study was to quantitatively examine the biomechanical variables of Fouette turns for expert and beginner ballet dancers and to determine the difference in the variables between the two groups. sixteen female ballet dancers participated in this study. They were divided into an expert group(age, $25.38{\pm}1.92$ years; height, $168.38{\pm}4.66$ cm; mass, $49.63{\pm}4.41$ kg) and a beginner group(age, $20.88{\pm}1.13$ years; height, $161.63{\pm}7.42$ cm; mass, $48.88{\pm}3.64$ kg) depending on their ballet experience. Descriptive data were expressed as mean ${\pm}$ standard deviation (SD) for all variables including the duration, displacement of the center of the body, velocity of the center of the body, angle of the body segments, angular velocity of the body segments, ground reaction force, lower extremity torque, muscle activity, body weight, age, and body mass. An independence t-test was conducted to determine how the following variables differed between the beginners and experts: duration, displacement of the center of the body, velocity of the center of the body, angle of the body segments, angular velocity of the body segments, ground reaction force, lower extremity torque, and muscle activity. All comparisons were made at the p<0.05 significance level. The results show that the experts scored high on the biomechanical variables, although all the variables were not significant. Significant differences were found in the angle of body segments, angular velocity of the body segments, lower extremity torque, and muscle activity(p<0.05). The findings of this study demonstrate that the experts have the required skill to make an improved Fouette turn. The findings may also help ballet dancers to learn and understand the Fouette turn.

• Korean Journal of Applied Biomechanics
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• v.15 no.4
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• pp.143-151
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• 2005

This study was conducted to investigate the technical factors of Cuervo forward straight vaults with single twist, single and half twists, and double twists actually performed by three execellent male gymnasts participated in artistic gymnastics competition of 2003 summer Universiade in Daegu and the 85th National Sports Festival in Cheongju. To accomplish the research goals the Cuervo vaults of three gymnasts were filmed by using three digital camcorders set by 60 Hz, and data were collected through the DLT method of three dimensional cinematography. The kinematic and kinetic variables as each phasic time, CM displacement velocity, release angle inclination angle hip joint angle landing angle, average horse reaction force average moment arm average torque, whoe body's total remote local angular momentum were analyzed, so the following conclusions were reached. Generally to perform the better Cuervo vault, a gymnast should touch down on the board with the great horizontal velocity of the whole body through the fast run-up, and touch down on the horse by decreasing the horizontal displacement of the whole body during the preflight, so raise CM height gradually within a short horse contact time. He should increase the horse reaction force through checking the horizontal velocity of the whole body effectively and the inclination angular displacement of the handstand, if so he can have the large vertical velocity of the whole body. By using the acquired the velocity and the angular momentum of the whole body, he can vault himself higher and twist sufficiently, then he can get better if the body could be tilted by swinging both arms and perform the cat twist with a little flexions at hip joints. According to the above outcomes we can judge that the best athletes is LuBin, the better is YTY, and the next is JSM.

• Advances in biomechanics and applications
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• v.1 no.1
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• pp.57-66
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• 2014

The purpose of the study was to investigate the kinematics between the double collar-tie and double underhook Thai Boxing clinching positions. Ten amateur mixed martial arts athletes executed six knee strikes for both clinching positions with their dominant limb directed towards a target. A standard two-dimensional video motion analysis was conducted, and the results showed a statistical significant difference at the hip joint angle and the angular acceleration of the knee and ankle. Within both clinching positions, there was a statistically significant correlation between the hip and knee joint angles, hip and knee angular velocities, and hip angular acceleration. Between both clinching positions, there was a statistically significant correlation at the knee joint angle, knee angular velocity, and hip angular acceleration. This study demonstrates the importance of the hip and knee joint movements in both clinching positions, which implies the applications of strength training and flexibility at these joints for sports performance and injury prevention. It is suggested that future studies analyzing the non-dominant leg are warranted to fully understand the Thai Boxing clinch.

• Physical Therapy Korea
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• v.2 no.1
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• pp.51-61
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• 1995

In general, research in isokinetic exercise has focussed on studies of peak torque. However, peak torque is not always sufficient to assess the real amount of motion or to determine endurance. In this study, the subjects were 54 healthy students who performed continuous maximal isokinetic knee flexion and extension until their total work per time reached 50% of their maximal total work. Isokinetic curves were then plotted. Total work sums, exercise durations in seconds, and the numbers of repetitions were compared with reference to subject gender, angular velocity and muscle group. The relationship between total work sum, duration and number of repetition and thigh circumference plus leg length was computed. In addition, the characteristics of total work per second and total work per time were calculated. Results showed the total work sums differed greatly from muscle group to muscle group and with different angular velocities. The duration in seconds and the numbers of repetition differed only at higher angular velocity. Males achieved higher levels in every category except for some duration in seconds and some numbers of repetitions. Thigh circumference and leg length were deciding fators in every case, but duration in seconds and number of repetitions were not. These results suggest that measures of endurance should be included along with measures of total work when isokinetic studies are done. Measures of endurance in seconds are more accurate when isokinetic exercise is performed at lower angular velocities and numbers of repetitions at higher angular velocities.

• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.2
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• pp.132-139
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• 2002

The grain size of aluminum alloy was refined to the submicrometer level by using equal-channel angular pressing(ECAP). The effect of grain size refinement was evaluated by the tensile test, micro-hardness test, microstructure observations, ultrasonic test and acoustic emission test. The strength and the Vickers hardness were increased significantly according to grain size refinement after equal-channel angular pressed. The ultrasonic velocity was faster after equal-channel angular pressed, and the high frequency range appeared. The results of the ultrasonic velocity and the frequency range are expected to be basic data that can prove the grain size refinement