• The Journal of the Korea Contents Association
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• v.12 no.1
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• pp.500-507
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• 2012

The purpose of this study was to investigate the effects of medicine ball throwing for weight shift training, that make improvements on golf physical fitness and performance. This training was related to physical fitness and golf performance in beginner golfer, undergraduates 20 males(10 exercise groups, 10 control groups) during 10 weeks. Variables were strength, flexibility, headspeed and distance. Training course were devided 2 sessions. In 1 to 5 weeks, using 3kg medicine ball, in 5 to 10 weeks, using 5kg medicine ball. Throwing method imitated golf swing, address, backswing, follow-through by throwing medicine ball. The Results were as follows; Medicine ball throwing for weight shift training showed significant difference in strength, flexibility, headspeed and distance in Exercise Group statistically. In conclusion, Medicine ball throwing for weight shift training improved strength, flexibility, headspeed and distance. So, it could be considered very effective training method as warming-up and main exercise.

• Physical Therapy Korea
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• v.16 no.1
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• pp.18-24
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• 2009

The purpose of this study was to assess the effect of bridging stabilization exercises on trunk muscles activity on and off a Swiss ball. 20 healthy university students volunteered to participate in this study. Subjects were required to complete following four exercises: exercise 1, single bridging exercise; exercise 2, feet on ball bridging exercise; exercise 3, calf on ball bridging exercise; exercise 4, back on ball bridging exercise. Surface electromyography from selected trunk muscles was normalized to maximum voluntary isometric contraction. A repeated measures of ANOVA with post-hoc Bonferroni's correction was used to determine the influence of exercise type on muscle activity for each muscle and descriptive statistics was used to determine local/global muscle ratios. The rectus abdominis of exercise 4 showed significantly higher muscle activity than rectus abdominis of exercise 1, 2, 3 (p<.05). The external oblique of exercise 2, 4 showed significantly higher muscle activity than external oblique of exercise 1 (p<.05). The internal oblique of exercise 2, 4 showed significantly higher muscle activity than internal oblique of exercise 1 (p<.05). The erector spinae of exercise 2, 3, 4 showed significantly higher muscle activity than erector spinae of exercise 1 (p<.05). Median of internal oblique/rectus abdominis ratio of exercise 1 was 1.16, exercise 2 was 2.43, exercise 3 was 2.45, exercise and 4 was 1.27. Median of internal oblique/external oblique ratio of exercise 1 was 1.01, exercise 2 was .91, exercise 3 was .99, and exercise 4 was .93. Muscle activity can be influenced by addition of a Swiss ball in bridging exercises. It is recommend to use a Swiss ball for trunk stabilization exercise.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.3 s.47
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• pp.321-328
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• 2004

Nano silica ball and nano carbon ball are developed commercially by template synthesis method. Adsorption of unpleasant smelling substances such as ammonia, trimethylamine, acetaldehyde and methyl mercaptane onto nano carbon ball with hollow macroporous core/mesoporous shell structures, nano carbon ball, was investigated and compared with that onto odor adsorbent materials, activated carbon, commercially available. The adsorption and decomposition of malodor at nano carbon ball exhibited superior than those onto activated carbon. The physicochemical properties such as mesopore size distributions, large nitrogen BET specific surface area and large pore volume and decomposition of malodor were studied to interpret the predominant adsorption performance. The nano carbon ball is expected to be useful in many applications such as deodorizers, adsorbent of pollutants.

• Tribology and Lubricants
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• v.36 no.6
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• pp.371-377
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• 2020

In In this study, we compared the results of a ball bearing life prediction model based on rolling element loads with the results of fatigue life prediction of ball bearings when a stress-based contact fatigue life prediction technique is applied to the ball bearing. We calculate the load acting on each rolling element by the external load of the bearing and apply the result to the Lundberg-Palmgren (LP) theory to calculate ball bearing life based on the rolling element. We also calculate stress-based ball bearing life through contact and fatigue analyses based on contact modeling of the ball and raceway while considering the fatigue test results of AISI 52100 steel. In stress-based life prediction, we use three high-cycle fatigue-determination equations that can predict the fatigue life when multi-axis proportional loads such as rolling-slide contact conditions are applied. These equations are derived from the stress invariant and critical plane methods and the mesoscopic approach. Life expectancy results are compared with those of the LP model. Results of the analysis indicated that the fatigue life was predicted to be lower in the order of the Crossland, Dang Van, and Matake models. Of the three, the Dang Van fatigue model was found to be the closest to the LP life.

• Journal of Powder Materials
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• v.28 no.6
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• pp.462-469
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• 2021

Tin/graphite composites are prepared as anode materials for Li-ion batteries using a dry ball-milling process. The main experimental variables in this work are the ball milling time (0-8 h) and composition ratio (tin:graphite=5:95, 15:85, and 30:70 w/w) of graphite and tin powder. For comparison, a tin/graphite composite is prepared using wet ball milling. The morphology and structure of the different tin/graphite composites are investigated using X-ray diffraction, Raman spectroscopy, energy-dispersive X-ray spectroscopy, and scanning and transmission electron microscopy. The electrochemical properties of the samples are also examined. The optimal dry ball milling time for the uniform mixing of graphite and tin is 6 h in a graphite-30wt.%Sn sample. The electrode prepared from the composite that is dry-ball-milled for 6 h exhibits the best cycle performance (discharge capacity after 50^th cycle: 308 mAh/g and capacity retention: 46%). The discharge capacity after the 50^th cycle is approximately 112 mAh/g, higher than that when the electrode is composed of only graphite (196 mAh/g after 50^th cycle). This result indicates that it is possible to manufacture a tin/graphite composite anode material that can effectively buffer the volume change that occurs during cycling, even using a simple dry ball-milling process.

• Journal of IKEEE
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• v.26 no.2
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• pp.150-159
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• 2022

In this paper, we propose a physics simulation for augmented reality (AR) billiards content. The characteristics of the physics simulation for the proposed AR billiards content are as follows. First, physical equations are derived by calculating the force and moment of inertia applied to the billiards ball to realize the motion of the billiards ball similar to the real one in the AR environment. Then, we determine the velocity and angular velocity of the virtual billiards ball associated with the rotation of the virtual billiards ball with respect to the impact point. Second, using some vectors such as incidnet vector, normal vector, reflection vector, the trajectory of the virtual billiards ball would be implement. these equations are applied to AR environment so that AR billiards content could be implement. This physics simulation allows users to feel like the real world using a virtual pool table and induce them to interact with the real environment. As a result of the experiment, the accuracy range between the path of the real billiards ball and the path of the virtual billiards ball was calculated to be 97.75% to 99.11%. Therefore, it was determined that the performance of the physics simulation for the AR billiards content proposed in this paper performs similarly to the path of the real billiards ball.

• Korean Journal of Materials Research
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• v.34 no.6
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• pp.309-314
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• 2024

The structure and magnetic properties of composite powders prepared by ball milling a mixture of Fe₂O₃·(0.4-1.0)Fe were investigated. Hysteresis loops and differential scanning calorimetry (DSC) curves are used to characterize the materials and to examine the effect of the solid state reaction induced by ball milling. The results showed that a solid state reaction in Fe₂O₃·(0.4-1.0)Fe clearly proceeds after only 1 h of ball milling. The system is characterized by a positive reaction heat of +2.23 kcal/mole. The diffraction lines related to Fe₂O₃ and Fe disappeared after 1 h of ball milling and, instead, diffraction lines of the intermediate phase of Fe₃O₄ plus FeO formed. The magnetization and coercivity of the Fe₂O₃·0.8Fe powders were changed by the solid state reaction process of Fe₂O₃ by Fe during ball milling. The coercivity of the Fe₂O₃·0.8Fe powders increased with increasing milling time and reached a maximum value of 340 Oe after 5 h of ball milling. This indicates the grain size of Fe₃O₄ was clearly reduced during ball milling. The magnetic properties of the annealed powders depend on the amount of magnetic Fe and Fe₃O₄ phases.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.449-450
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.21-22
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.359-360
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• 2010