• Korean Journal of Applied Biomechanics
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• v.19 no.2
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• pp.323-336
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• 2009

The purpose of the current study was to research scientific basis and necessity of supplementary materials for field lesson out of golf swing teaching methods. As the subject of study, skillful tour pro golfers were chosen to reinterpret field lesson results for driver swing from the viewpoint of kinematics. In addition, through precise analysis, this study developed a case to verify the validity and error of field lesson. As a result, field lesson showed a slight difference among qualitative evaluation of kinematical analysis of techniques, subjects of study, and items. Accordingly, there was a little difference between two methods in view of evaluation of errors that 5 subjects of the study have shown. However, there was a significant difference in compensation to prevent causes of error and errors. Based on instructor's experience most errors could be evaluated. Therefore, feedback for error correction based on instructor's experience showed a significant difference from qualitative evaluation of kinematical analysis of techniques. In conclusion, the following are required for correct golf swing lesson; instant feedback through field lesson and qualitative evaluation of kinematical analysis of techniques to determine fundamental causes correctly.

• Korean Journal of Applied Biomechanics
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• v.18 no.3
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• pp.43-80
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• 2008

The purpose of this research is to analysis the swing of driver used by professional golfers during on-season. In order to collect on-season driver swings of research objects, which are three KPGA(Korean Professional Golfer Association) professional golfers, measurements were carried out right after the last game of a season. The analysis range was set to down-swing point while analysis was conducted to after-impact, release point. As a result, systematic process between leading segments of the previous precise kinematic analysis research seems to turn up the same. However, there were different results compared to the preceding research. All three testers expressed adduction of left hand which could not be described with forming cocking angle, in consequence, adduction of left hand does not have a big effect on formation of cocking. Moreover, chest movement right before the impact; which was emphasized in previous research, the direction was not opposite but the same with the ball.

• Korean Journal of Applied Biomechanics
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• v.19 no.2
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• pp.273-286
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• 2009

The objective of this research is to evaluate both quantitative analysis and qualitative analysis by comparing vital variable factors of the golf swing successes and the failures. At the moment of swing, each body segment and the movement of the club as well as kinematical parameters were produced by utilizing the 3-D swing analysis for the high school female golfers. As kinematical parameters, it analyzes the 3-D analysis and ground reaction force about the location change, velocity and angle. The 3-D swing analysis and ground reaction force location change, velocity and angle are analyzed for Kinematical parameters. As a result, the stable swing is maintained by club head showing very few front-back movement (X) when the address and the top swing. Also, the center of mass velocity contributes to the momentum increase by showing very rapid velocity when successful comparing with when failed at the time of top swing of left-right(Y) and it is thought that by lessening the cocking angle when successful from the top swing to the impact, it influences the linear velocity increase and has a good effect on a non-distance increase. It shows that Ground reaction force (GRF) is examined by showing the stable approval rating in a front-back(X) direction and left-right(Y) and connected to a successful swing.

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

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.6
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• pp.1-13
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• 2003

This study aims at conducting an awareness survey of three parties, namely, citizens, government officials, and developers for improvement of urban landscape and, based on the survey result, to suggest a direction to develop a landscape plan for improvement of urban landscape of Yong-in city in the future. The summary of this study is as follows. First, in case of Yong-in, the main drivers of forest landscape destruction were "residential complexes developed for apartment buildings" and "golf courses", the driver of river landscape damage was "the status of cleanliness of riverside and poor facilities", the driver of roadside landscape damage was "construction sites" that completely eliminate original natural landscape in both citizen and government official groups. When granting development-related approvals in the future, appropriate actions should be prepared such as developing a landscape management guideline or including a landscape plan in advance to assure plans and designs fully reflecting landscape. Second, citizens' commitment to participate in urban landscape creation and improvement was rated high at even willing to tolerate regulations including restriction of property rights. In the future, landscape improvement programs allowing resident participation should be developed proactively. The roles of government officials include preparing various criteria at a city level and convincing and guiding citizens to initiate landscape improvement project together with citizens and developers through proactive efforts by government officials. Third, the role of developers would be to realize development projects conserving local environment and/or harmonizing with local natural environment before preparing a development plan or launching construction rather than offering various considerations after executing development projects.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.6
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• pp.74-80
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• 2009

Path tracking of unmanned vehicle is a basis of autonomous driving and navigation. For the path tracking, it is very important to find the exact position of a vehicle. GPS is used to get the position of vehicle and a direction sensor and a velocity sensor is used to compensate the position error of GPS. To detect path lines in a road image, the bird's eye view transform is employed, which makes it easy to design a lateral control algorithm simply than from the perspective view of image. Because the driving speed of vehicle should be decreased at a curved lane and crossroads, so we suggest the speed control algorithm used GPS and image data. The control algorithm is simulated and experimented from the basis of expert driver's knowledge data. In the experiments, the results show that bird's eye view transform are good for the steering control and a speed control algorithm also shows a stability in real driving.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.31-40
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• 2007

Proper weight shifting is essential for a successful shot in golf swing and this could be described by means of the ground forces between the feet and ground. It is assumed that the ground forces would different according to the club used because the length and swing weight of each club is different. But, in present, it is not clear what changes are made by the change of clubs and this affect the swing motion. Therefore this study focused on the investigation of the changes of the ground forces and ground reaction forces (GRF) by the change of club length. The subjects were three professional male golfers. Four swings (driver, iron 3, iron 5, and iron 7) for each subject were taken by two high speed video cameras and two AMTI force platforms were used to measure the GRF simultaneously. Kwon GRF 2.0 and Mathcad 13 software were used to post processing the data. Changes of the three major component of GRF (Vertical, lateral, anterior-posterior force) at 10 predefined events were analyzed including the maximum. Major findings of this study were as follows. 1. Vertical forces; - There were no significant changes until the top of backswing. - Maximum was occurred at the club horizontal position in the downswing for both feet. The shorter club produced more maximum forces than longer ones in the left foot, but reverse were true for the right foot. - Maximum forces at impact shows the same patterns. 2. Lateral forces; Maximum was occurred at the club horizontal position for both feet, but there were no lateral forces because the direction of two forces was different. Maximum force pattern by different clubs was same as the vertical component. 3. Anterior-posterior forces; - This component made a counter-clock wise moment about a vertical axis located between two foot until the club vertical position was reached during the backswing, and reverse moment were produced when the club reached horizontal at the downswing. - Also this component made a forward moment about a horizontal axis located in the CG during the fore half of the downswing, and a reverse moment until the club reached vertical at the follow through phase. Maximum was occurred at the club vertical in the downswing for both feet. The longer club produced more maximum forces than shorter ones for both feet.

• Korean Journal of Applied Biomechanics
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• v.19 no.3
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• pp.557-566
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• 2009

This study was to investigate gender differences in muscle activities on tibialis anterior muscle, gastrocnemius and vastus medialis obliqus and outside and prime mover, antagonist and assistance mover during golf drive swing by electromyography. Ten healthy professional golfers (KPGA(n)=5, KLPGA(n)=5) volunteered in this experiment. All statistical analyses were performed using SPSS. Statistical differences were assess using t-test (p<.05). The conclusion of this study was as following. Muscle dislocation of differences, according to gender, was the highest in case of males in right side of gastrocnemius with the section from the address to the backswing of top and was the highest in case of females in tibialis anterior muscle. Results also show that prime mover was left side of low muscle in case of male with all the sections and situations and is right side low muscle in case of female. These results were significant differences. In case of males, it was though that primer mover was left side of tibialis anterior muscle with moving weight from backswing of top till the address section. In case of females, primer movers were right side of vastus medialis obliqus and tibialis anterior muscle with pushing action form the right knee to the left knee. Therefore, if they try to do the training be able to development right side of vastus medialis obliqus and tibialis anterior muscle in case of females and left side of vastus medialis obliqus and tibialis anterior muscle in case of males, it is consider that golfers' distance and direction will get better.

• Korean Journal of Applied Biomechanics
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• v.25 no.2
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• pp.149-155
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• 2015

Purpose : Recently, many researchers and golf coachers demonstrated that X-factor and X-factor stretch had a co-relationship with driving distance. However, its relationship is still controversial and ambiguous. Thus, the aim of this study was to examine the relationship among X-factor, X-factor stretch and swing-related factors, including driving distance in elite golfers. Method : Seventeen male elite golfers (handicap: ${\leq}4$) with no history of musculo-skeletal injuries participated in the study. Thirty spherical retro-reflective markers were placed on including the middle point of PSIS, the right/left ASIS, the right/left lateral acromion of the scapula, driver head and shaft grip. All motion capture data was collected at 100Hz using 6 infrared cameras. Carry distance, club speed, ball speed, smash factor, launch angle, and spin rate were collected from radar-based device, TrackMan. Results : Pearson's correlation coefficient method was used to find the correlations among X-factor, X-factor stretch and swing-related factors. Positive correlations between driving distance and other swing-related factors which include club speed(r=.798, p<.001), and ball speed(r=.948, p<.001) were observed. In contrast to the swing-related factors, X-factor and X-factor stretch had no relationship to driving distance. Conclusion : These results indicate that X-factor and X-factor stretch are not key regulators in driving distance.

• Korean Journal of Applied Biomechanics
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• v.15 no.3
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• pp.71-78
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• 2005

The purpose of this research was to conduct an analysis on the factors that determine the distance at the time of target swing based on the use of late hitting of outstanding college golfers to verify the difference between late hitting and the distance that target increases in regular swing and the distance. Then, this research conducts an analysis on the correlation between club head velocity, ball velocity, launch angle, back spin, meet ratio and distance that become kinematics variables at the time of target swing. To attain the above mentioned purpose, 25 outstanding college players with average experience and handicap of 6 years and 5, respectively, were targeted Comparative analysis on two swing that target increase in regular and the distance was conducted by used driver. When it pertained to two types of swing. analysis system comprised of an analytical software called the Science Eye of the Bridgestone and peripheries was used to define the relationship between variables of club head velocity, ball velocity, launch angle, back spin, meet ratio that become kinematics variables. As for the method of processing data pertaining to the factors that determine the distance, differences of distance by the type of swing was verified by using independent T-test that leveraged SPSS 120 statistics program. Moreover, level of correlation between variables that contribute to the increase in distance through relation of correlation, and analysis of tendencies was conducted to analyze tendency of non-distance to increase in accordance to the increase of each variable. Key results produced through this experiment are as follows: 1. Artificial late hitting for increased non-distance that targets skilled players had effect on increased the distance(p<. 05). 2 The drive distance is correlated with each measured variable that is positive correlation to ball velocity, club head velocity, meet ratio and relation of back spin and launch angle are negative correlation. ball velocity and club head velocity are very high correlated with drive distance(p<.01), back spin and distance are negative correlation(p<.01). 3. Among each measured variable increasing the club velocity is the most contribution, and ball velocity and meet ratio and the increasing launch angle and back spin is negative effect for increasing distance.