• Korean Journal of Applied Biomechanics
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• v.32 no.1
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• pp.1-8
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• 2022

Objective: This study proposes a methodology to analyze important variables that have a significant impact on the putting direction prediction using a machine learning-based putting direction prediction model trained with IMU sensor data. Method: Putting data were collected using an IMU sensor measuring 12 variables from 6 adult males in their 20s at K University who had no golf experience. The data was preprocessed so that it could be applied to machine learning, and a model was built using five machine learning algorithms. Finally, by comparing the performance of the built models, the model with the highest performance was selected as the proposed model, and then 12 variables of the IMU sensor were applied one by one to analyze important variables affecting the learning performance. Results: As a result of comparing the performance of five machine learning algorithms (K-NN, Naive Bayes, Decision Tree, Random Forest, and Light GBM), the prediction accuracy of the Light GBM-based prediction model was higher than that of other algorithms. Using the Light GBM algorithm, which had excellent performance, an experiment was performed to rank the importance of variables that affect the direction prediction of the model. Conclusion: Among the five machine learning algorithms, the algorithm that best predicts the putting direction was the Light GBM algorithm. When the model predicted the putting direction, the variable that had the greatest influence was the left-right inclination (Roll).

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1496-1500
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• 2008

Less than 1 % directional error in the range of 5 meters in the green could cause a stroke or more. Although there are several reasons offsetting the direction of the golf ball, lie angle and sidespin effect are the most crucial factors of the putting game. Simple equation is conformed to the experimental results of the deviation of the directional error in all distance. Also, the experimental results of the putting robot show that there are significant side spin effects.

• Korean Journal of Applied Biomechanics
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• v.20 no.2
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• pp.239-243
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• 2010

The putting stroke accounts for 40~50% of total stroke for a golf rounding and most golfers have difficulties on the puting. Studies for the putting stroke have been conducted by analyzing various factors such as kinematics, kinetics, psychologic and physiologic parameters. A lot of devices were developed to support the studies. However there was no appropriate method to measure the position of the ball quantitatively. In this study, we developed a new measurement system to measure and evaluate the putting result. The developed system uses a USB camera to take the 2-dimensional image of the surface including the hole cup at the center of the image and the ball. The position of the ball is extracted as a set of distance and angle in polar coordinate system. We evaluated the new system with an indoor set-up for putting experiments and the system provided accurate measurement results. The proposed system can be combined with the other measurement systems such as 3D motion capture system and force plate without any restriction.

• Asian Journal of Turfgrass Science
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• v.18 no.2
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• pp.97-104
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• 2004

Anaerobic soils limit the amount of free oxygen available in the rhizosphere and therefore will impede grass root development and restrain nutrient availability for turf growth. An in-situ study was conducted on existing greens to investigate the relationship between $CO_2$ content in the rhizosphere and turf quality. Nine greens were selected in the study. On each green, five 1-m diameter circular plots were randomly selected for conducting the experiment. The greens were sampled 7 times from August, 1998 to August, 1999. Data collected from each plot included turf quality index, $CO_2$ content, and physical properties of the rooting mixtures. Turf quality declined drastically when $CO_2$ content in rhizosphere increased to $5\;to\;6{\mu}LL^{-1}$ during the late summer season. The $CO_2$ content increased as water content in the root zone increased, but was inversely related to infiltration rate. Cultivation of a golf green may reduce $CO_2$ content in the rhizosphere, but the benefit of cultivation decreased with time.

• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.448-455
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• 2019

This study aims to discover whether there are other factors, such as the ball position and address that will increase the percentage of holed putts from different angles of surface. In this study, we selected five male tour professional golfers that has been of 15 years or longer on the Korea Golf Association. As a research tool, after installing a video camera at an artificial site that's similar with the real green, and with the player's own putter, motion analysis was carried out using a Titleist V1x, which is commonly used by golfers. We use SPSS programs, significance level a=.05. According to the ball movement during the ball movement during the ball position putt by section, it is confirmed that the ball speed and angular velocity increase as the ball position changes from left to right. If the uphill putt, ball movement was found to be increased same change flat putt and There is no significance deviation. In this study, we investigate how the clubface and ball move during impact by varying the position of the address ball according to the slope during the ascent putt, which should increase the success rate among the various slopes. This study was conducted to present scientific data.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.217-226
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• 2007

Putting score counts about 43 % of the golf score. The dominant idea of the putting motion to amateur golfers as well as to many professional golfers is a pendulum-like motion. If a golfer's putting stroke motion is a pendulum-like motion, the putting motion should be straight-back-and-through, the same backswing, downswing, and follow through length and period, and a swing with a fixed hinge joint. If the putting motions of the human are different from the pendulum motion, there could be confusion in understanding and teaching golf putting. The purpose of this study was to examine the center of rotation(COR) of the putter head to reveal whether professional golfers really putt like a pendulum. Thirteen male professional golfers were recruited for the study. Each golfers executed 10.94 m putts six times on an artificial grass mat. Putter head position data were collected through a 60 Hz three-dimensional motion analysis system and low pass filtered with cut-off frequency of 6 Hz. COR of the putter head was mathematically acquired. Each golfer's last five putting motions were considered. The results show that the COR of the putter head was neither fixed nor located inside of the golfer. The medio-lateral directional component of the COR of the putter head fluctuated in the range of 10 cm during downswing and follow through. The anterior-posterior directional component of the COR of the putter head was fixed from the beginning of the downswing through impact. Just after impact, however, it moved to the target up to 60 cm. The superior-inferior directional component of COR of the putter head moved in a superior direction with the beginning of the downswing and showed peak height just prior to impact. During the follow through, it moved back in an inferior direction. The height-normalized peak value of the COR of the putter head was $1.4{\pm}0.3$ height. Technically speaking, male professional golfers' 10.94 m putting motion is not a pendulum-like motion. The dominating idea of a pendulum-like motion in putting might come from the image of the flawless, smooth motion of a pendulum.

• Asian Journal of Turfgrass Science
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• v.19 no.2
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• pp.95-102
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• 2005

USGA green specification is currently accepted in construction method of Korea. This study was carried out to find the factors influencing growth of turfgrass associated with soil physical properties of soil root-zone on golf green constructed with USGA method. Three putting greens in poor turfgrass and one in good turfgrass condition were selected for investigation on one golf course site at mid-South Korean peninsula. Soil hardness, moisture content, root length, and turf density were measured on-site greens, and soil physical properties and soil chemical properties also analyzed in laboratory. As a result of on-site surveys and soil physical tests in laboratory, soil physical properties were most important factors which influenced on turfgrass growth at tested greens. The results of soil particle analysis on green No. 2, in good turf condition, matched USGA sand particle recommendations. But those greens such as Nos. 1, 11 and 16, in poor putting greens, showed high soil compaction and improper soil particle distribution. Those factors created low leaf density, poor root depth, and higher moisture content compared with lower part of topsoil. Such phenomena caused inadequate turfgrass growth with soil hardening associated with poor drainage. Therefore, declines of soil physical properties associated with improper particle distribution caused a major factor influencing on turfgrass growth in golf green. Adequate test of soil particle analysis by USGA specification and proper construction method followed by adequate turf maintenance should be performed to obtain optimal turf quality on putting green.

• Korean Journal of Applied Biomechanics
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• v.29 no.4
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• pp.205-211
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• 2019

Objective: The purpose of this study was to analyze the effects of skill and distance factors on CoP (Center of pressure) and CoM (Center of mass) during golf putting. Method: 38 golfers were participated in this study. 8 motion capture cameras (250 Hz) and 2 force plates (1,000 Hz) were used to collect CoP and CoM during 2 m and 3 m of distance golf putting. To identify main effect and interaction effect, it was performed Two-Way ANOVA at a significant level of a .05. Results: In the novice group, CoP distance was significantly difference in the A/P direction and main effect between skill level and distance. Both groups indicated that CoP distance was significantly different and main effect between skill level and distance in the M/L direction. Finally, both groups showed that CoM was significantly different and main effect between skill level and distance in the M/L direction. Conclusion: Therefore, novice golfers are expected to be able to perform more accurate and proper putting exercise through the practice of minimizing the center of mass(CoM) and center of pressure (CoP) in the M/L direction, which is the pendulum movement of the putter head.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.827-829
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• 2016

In this paper, in order to achieve the user's convenience in golf putting during practice, to provide a method of tracking the golf ball using a high speed camera. This is recently, it is to analyze so that you can hit a golf putting part of the leisure sport to enjoy a lot of people accurately. The proposed method, the pixel when using a common USB camera is blurred, since the golf ball detection rate is low and using a high-speed camera capable of measuring up to per second 380 frames. First, by using the Hough transform after pretreatment, to detect a golf ball. Movement path by using the information subsequently detected golf ball, calculating the moving distance and angle. The proposed method result of applying, improved travel route detection rate of the golf ball is improved, the accuracy of the moving distance and angle.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.55-56
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• 2007