• Korean Journal of Applied Biomechanics
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• v.17 no.4
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• pp.83-88
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• 2007

The purpose of this study was to investigate the ball velocity changes depending on the different linear momentum of putter head. For this study, two different moving conditions(25cm free fall and 35cm free fall) of putter head were set. And two different types of ground conditions were used which are artificial grass green($180cm{\times}600cm{\times}1cm$) and glass green($40cm{\times}130cm{\times}1cm$). Movements of putter head and ball were recorded with 2 HD video cameras(60 Hz, 1/500s shutter speed). Small size control object($18.5cm{\times}18.5cm{\times}78.5cm$) was used in this study. Ball and putter head velocities were calculated by the First Central Difference Method(Hamill & Knutzen, 1995). Linear momentum of ball and putter head were calculated with mass and its velocities. Before impact, the velocity of the putter head of 35cm free fall was about 30% greater than that of the putter head of 25cm free fall. Linear momentum of putter head of 35cm free fall was about 0.355-0.364kg m/s and 25cm free fall was 0.251 kg m/s. After impact, putter head lost its linear momentum about 14-19% and adjusting time of putter head after impact would be 0.1 second. After 0.1 second, putter moved the route same as before impact. Maximum ball velocities were appeared 0.08s-0.10s after impact no matter what the ground conditions are. Ball velocities struck by 35cm free fall were 30 % faster than 25cm free fall. Linear momentum of ball struck by putter head was greater than that of expected amount because the moving ball has translational energy and rotational energy. Future study must treat three things. One is ball must struck by the different putters with different materials. Another is two-piece ball and three-piece ball should be used for the same condition studies. The other is height of center of rotation of club should be changed. In this study, the height of center of rotation of club head is 71cm from the ground. But recently many golfers used the long putter. Therefore next study should apply the different height of center of rotation of club head.

• Korean Journal of Applied Biomechanics
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• v.13 no.2
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• pp.175-183
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• 2003

The purpose of this study was to analyze the kinetic energy of putter head and ball movements during the process of impact. Highly skilled 5 golfers(less than 1 handicap) participated in this study and the target distance was 3 m. Movements of ball and putter head were recorded with 2 VHS video cameras(60 Hz, 1/500 s shutter speed). Small control object($18.5{\times}18.5{\times}78.5\;cm$) was used in this sdtuldy. Analyzing the process of impact, putter was digitized before 0.0835 s and after 0.0835 s of impact. Ball was digitized 0.1336 s after impact. The results showed that the maximum speed was appeared at Impact and prolonged for a while. Contact point of the club head was within 0.7 cm to the z axis. After contacting the club head, the ball was moved above the ground level(slide) and returned to the ground with sliding and rolling. After contacting the ground, the speed of ball was relied on the surface of the ground. During impact, 70% of kinetic energy of club head has been transferred to the ball.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2005.11a
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• pp.179-180
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• 2005

Non linear finite element analyses were performed in various configurations of stem-ball head. High stresses were found for the cases when the stem tended to penetrate less into the ball head. An upgraded design of the cone may improve the loading of the ball head to resist trauma-like loading more effectively than manipulating the ball diameter. When the surgeon needs to use small ball heads (i.e. 22 mm), the use of zirconia seems to be appropriate also. After simulating a trauma like loading of the materials, it was found that the deepness of the cone to locate the stem is of major importance for the performance of the device. Further work, considering more sizes for the cone design should be performed in order to determine an optimal depth for the cone in relation to the diameter of the ball head. Also the simulation of contacts pairs including polyethylene and CoCr is important for further research.

• Korean Journal of Applied Biomechanics
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• v.22 no.1
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• pp.75-82
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• 2012

The purpose of this study was to suggest the proper shaft and head fitting methods of the golf club to increase the flight distance of the golf ball. Rotations per minute of the golf ball(RPM), ratio of Ball speed to club head speed(T-Ratio) and launch angle right after impact(LA), which are directly related to ball flight distance, were measured using Spectra with shutter speed of 1/1000sec at the constant head speed of 95mph which was controlled by robot golf swing machine. In order to investigate the effect of club shaft to the 3 selected variables, 10 shafts were used to make ten test clubs with one controlled club head which is the most commonly used by golf players. To measure the effect of the club head to the 3 selected variables, 6 golf club heads which are most commonly used by golfers were selected to make 6 test clubs with a controlled shaft which is one of the best known by players. The shafts and the heads were identified by statistical analysis to increase or decrease the RPM, T-ratio and LA. A proper fitting method of the selected shafts and the club head was suggested to increase the ball flight distance in golf.

• Journal of the Korean Society of Physical Medicine
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• v.12 no.3
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• pp.111-117
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• 2017

PURPOSE: To determine the effect of weight ball throw training as a preparatory exercise before golf practice for 8 weeks on back muscle strength, weight shifting of lower body, head speed of club, and driving distance of amateur golfers. METHODS: A total of 18 subjects were randomly assigned to the experimental group (n=9) and the control group (n=9), respectively. For the experimental group, Weight ball throw training was provided to the height of waist and shoulder similar to golf swing with the following schedule: 3 kg weight ball throw training from the first week to the 4th week; 5 kg weight ball throw training from the 5th week to the 8th week. Before and after 8 weeks of training, back muscle strength, weight shifting of lower body, head speed of club, and driving distance of subjects in the two groups were measured. RESULTS: The experimental group showed significant differences in rotational back extension torque, weight shifting of lower body, head speed of club, and driving distance during golf swing (p<.05). However, the control group only showed significant difference in driving distance during golf swing (p<.05). Back extension torque, weight shifting of lower body, and head speed of club showed significant differences between the two groups during golf swing (p<.05). CONCLUSION: Weight ball throw training can positively change rotational back muscle strength, weight shifting of lower body, head speed of club, and driving distance of amateur golfers. Therefore, it might be used as an effective warming up exercise for amateur golfers.

• Korean Journal of Audiology
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• v.24 no.4
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• pp.210-213
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• 2020

Fungal balls consist of rounded conglomerates of fungal mycelia, which can form within a preexisting cavity. They are mostly found in the paranasal sinuses in the head and neck regions. Cholesterol granuloma is a fibrotic lesion that develops as a tissue response to a foreign body such as cholesterol crystals or hemosiderin and is often associated with chronic otitis media. We present the unusual case of a 62-year-old male who was treated for chronic otitis media, which was histologically confirmed as a fungal ball and cholesterol granuloma in the middle ear cavity following tympanomastoidectomy. This is the first reported case of synchronous fungal ball and cholesterol granuloma in the middle ear cavity.

• Journal of Audiology & Otology
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• v.24 no.4
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• pp.210-213
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• 2020

Fungal balls consist of rounded conglomerates of fungal mycelia, which can form within a preexisting cavity. They are mostly found in the paranasal sinuses in the head and neck regions. Cholesterol granuloma is a fibrotic lesion that develops as a tissue response to a foreign body such as cholesterol crystals or hemosiderin and is often associated with chronic otitis media. We present the unusual case of a 62-year-old male who was treated for chronic otitis media, which was histologically confirmed as a fungal ball and cholesterol granuloma in the middle ear cavity following tympanomastoidectomy. This is the first reported case of synchronous fungal ball and cholesterol granuloma in the middle ear cavity.

• Journal of the Korea Society of Computer and Information
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• v.18 no.9
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• pp.71-78
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• 2013

In this paper, the golf club head hit the golf ball moves at a constant velocity, then move in the same direction at a constant velocity of the golf club head, the velocity of the golf ball was hitting and flying the golf ball is calculated. If velocity is different before you hit the golf ball, each of the velocity of the golf ball is calculated. The purpose of this paper is to make it easy to find out the velocity of a club's head, the mass of a golf ball, the velocity or the direction of a golf ball after impact in playing golf. The results of the experiment are represented in tables and figures. And we also propose the comparison analysis between our research and other traditional ones, the implications, and futhur studies in the future. The results of this study, unlike other studies, it was can be seen that measurements of several factors superior to the measurement of the velocity of the golf ball.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.3
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• pp.35-39
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• 2020

Nonwet (Head in Pillow) defect is one of the defects in SMT (surface mount technology) process, the defect is caused by several factors, such as solder paste misalignment, reflow condition, package warpage and package ball size. This paper focused on ① reflow condition ② package ball & solder paste misalignment ③ package ball size for nonwet experiment. The first, on the case of reflow condition, there would be high risk of nonwet defect when the soldering time was increased, but N₂ was adopted to reflow process, there could be no or low risk of nonwet defect because of oxidation barrier control. And when the contact depth between Solder ball and solder paste was below 20 ㎛, there could be high risk of nonwet defect. Also smaller package ball would have low risk of nonwet defect.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.129-131
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• 2013

In this paper, a golf club head strikes the golf ball moves at a constant speed. Then the head of a golf club moves at a constant speed in the same direction. Then calculate the speed of the golf ball to hit a golf ball flying. It calculate the speed of the golf ball is different for each speed before hitting the golf ball.