• Title/Summary/Keyword: Ball speed

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The Movement of Foot and the Shift of Ground Reaction Force in Batters according to the Ball Speed Increase (투구 속도 증가에 따른 타자의 발 움직임과 지면 반력의 변화)

  • Lee, Young-Suk;Eun, Seon-Deok
    • Korean Journal of Sport Biomechanics
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    • v.14 no.3
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    • pp.191-202
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    • 2004
  • The batting performance in baseball is a repetitive movement. In order to make the stabilization of posture and the efficient shift of body weight, both the range of stance and stride are important. The previous studies explained that the consistent stride which included the amount of time, stance, and direction were needed. However, the batting performance is frequently changed according to the several speed of ball. Therefore, this study was to analyze the reaction time, the range of stance, the change of stride, and the change of GRF during the batting movement in three kinds of ball speed (120km/h, 130km/h, & 140km/h). Seven elite players are participated in this study. 1. The reaction time of the stride phase was short whereas the time of the swing phase was long according to the increasing ball speed. 2. The range of the stance was wide and the mediolateral direction of the stride was decreased according to the increasing ball speed. 3. In the three kinds of ball speed, the change of body weight was transferred to the center, the rear foot, and the front foot directions. The ball speed of 130km/h showed the high frequency of the suitable batting. At this ball speed, the movement of the body weight was shifted smoothly and the value of the Ground Reaction Force was large enough.

Effect of Different Golf Shoe treads on Wear and Ball Speed of Putting Green (퍼팅그린의 마모와 골프공의 구름에 미치는 골프화의 영향)

  • 심포룡;심규열
    • Asian Journal of Turfgrass Science
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    • v.11 no.3
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    • pp.205-210
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    • 1997
  • The metal spikes evaluated in this study significantly affected more negative on the turf wear and ball speed of putting green than alternative plastic spikes. 1.The metal spikes caused the most amount of wear compared with plastic spikes, athletic shoes and mountain-climbing shoes. On the other hand, athletic shoes caused the least amount of wear. Plastic spikes caused wear more than athletic shoes, hut apparently wear less than metal spikes. The wear from metal spike repaired later than any other tread types. 2.The wear from all kinds of shoe treads in wetcondition green were higher than in dry-condition green and the wear from metal spikes was more severe compared with plastic spikes in both green condition. 3. Ball speed of heavy compaction area by metal spike was reduced about 9% compared with that of light compaction area, hecause metal spikes made many holes in the putting green surface. On the other hand, plastic spikes did not affect hall speed of heavy and light compaction area in the putting green. Key words: Metal spike, Plastic spike, Wear, Ball speed.

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The Effect of PNF Stretching with Elastic Band on Ball Speed of High School Baseball Players (탄력밴드를 이용한 1회성 동체 PNF 스트레칭이 고등학교 야구선수의 피칭속도에 미치는 영향)

  • Lee, Sang-Won;Kim, Won-Hyun;Kim, Do-Youn
    • Journal of Digital Convergence
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    • v.14 no.12
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    • pp.525-535
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    • 2016
  • The purpose of this study was to evaluate the effect of thoracic dynamic stretching with elastic band on the ROM and ball speed for baseball player. For this purpose, 11 baseball players of the I city high school and university performed thoracic dynamic stretching with elastic band before throwing a ball. After stretching, we measured the ROM and ball speed and compared. The results were as follows. First, ROM after stretching showed a significant increase immediately compared with before stretching. Second, the speed of the ball was significantly increased after stretching compared with before. These results indicated that thoracic dynamic stretching with elastic band for baseball players might have a positive effect on ball speed as well as ROM.

Golf driver shaft variability on ball speed, head speed and fly distance (골프 드라이버 샤프트의 가변성이 타구속도, 헤드스피드 및 비거리에 미치는 영향)

  • Jung, Chul;Park, Woo-Yung
    • Journal of the Korean Applied Science and Technology
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    • v.35 no.1
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    • pp.273-283
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    • 2018
  • The purpose of this study is to analyze the optimum driver selection according to shaft intensity, shaft length and shaft weight that are determining factors of driver shot. To achieve the above purpose, the subject were participate with handicap zero 10 male pro golfer and mean score 90(handicap about 18) amateur 10 male golfer. The used club limited number 1 driver, we tested 24 driver which is shaft intensity, length, weight, total weight and swing weight. Dependent variable was strike ball speed, flying distance and head speed. The findings can be summarized as follows. First, There is a significantly difference in CPM. Ball speed, head speed and flying distance according to driver shaft intensity were found to be the best when CPM is 230<. Second, There is a significantly difference in shaft length. Ball speed, and head speed according to driver shaft length were found to be the best at 46 inch and flying distance were found to be the best at 45 inch. Third, There is not significantly difference in SW. Ball speed and flying distance according to driver shaft weight were found to be the best with 65g. In the case of head speed, it was the fastest with 50g shaft. Four, total variables were significantly difference between in pro and amateur golfer. In conclusion, there would be differences in individual physical condition but the best result was found with a driver of CPM 230<, shaft length 46inch, and shaft weight 65g.

The Effects of a Shoulder Complex Stabilization Exercise Combined with Upper Extremity Patterns on Ball Control and Ball Speed in Elementary School Baseball Players (상지 패턴을 결합한 어깨 복합체 안정화 운동이 초등학교 야구선수들의 제구력과 구속에 미치는 영향)

  • Jeong, Yeon-Woo;Lee, So-Young;Seo, Tae-Hwa
    • PNF and Movement
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    • v.18 no.3
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    • pp.343-350
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    • 2020
  • Purpose: The purpose of this study was to determine how a shoulder complex stabilization exercise affects ball control and ball speed in elementary school baseball players with an instable scapula. Methods: The subjects of the study were 16 baseball players attending S elementary school in Kwangju Metropolitan City. A shoulder complex stabilization exercise was conducted three times per week for one hour for four weeks. Then, the participants were divided into a scapular instability group or stability group based on their lateral scapular slide test scores. The measurement tool was measured using the target, the ball speed tester (PR1000-BC). All inspections were measured before and after the mediation period to examine the change in the subjects according to the mediation period. Results: As a result of measuring ball control, there was a statistically significant difference in the variation over time (p < 0.05), and there was no statistically significant difference in the interaction between time and group (p > 0.05). As a result of the test of effectiveness between subjects, there was no statistically significant difference found among the groups (p > 0.05). In terms of ball speed, there was no statistically significant difference found in the variation over time (p > 0.05) as well as in the interaction between time and group (p > 0.05). In terms of the effectiveness between subjects, there was no statistically significant difference found among the groups (p > 0.05). Conclusion: It was found that the shoulder complex stabilization exercise could improve ball control for elementary school baseball players. It is believed that this will help prevent and solve possible sport damages experienced during training or competitions, thereby helping athletes use training methods to improve their exercise capacity and continue their careers.

Implementation of a PLC-based Pitching System capable of Pitching a Breaking Ball (변화구 투구가 가능한 PLC기반의 피칭 시스템 구현)

  • Kim, Min-Kyu
    • Journal of Sensor Science and Technology
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    • v.27 no.6
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    • pp.380-385
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    • 2018
  • Recently, interest in baseball has been increasing as the level of international baseball games, the popularity of domestic leagues, and the number of players entering the MLB has increased. In this paper, we propose a pitching system that can be applied to both professional and amateur baseball. The pitching system consists of a control module using MSB764T PLC, a pitching mechanism including AC motors and a ball feed rail, an HMI using the CHA-070WR model, inverter, etc. To pitch the breaking balls, the two AC motors each use an inverter to independently control the speed. The implemented pitching system was experimented on, investigating ball speed and ball movement according to RPM using the BUSHNELL Velocity Speed Gun. Experimental results on ball speed are similar to the theoretical data and the measured data. From the experimental data, it is confirmed that the damping coefficient value for the pitching ball is about 0.98. In the case of the breaking ball, the larger the difference between the speeds on the sides of the ball and the faster the ball speed, the larger the bending degree.

Analyze the Correlation between Variable Factors, Kinematic Factors(x-factor, x-factor stretch) and Club Impact Factors, Affecting the Total Length of the Ball During a Pro-Golfer's Driver Swing (프로골퍼의 드라이버 비거리증가를 위한 목적스윙 시 X-Factor, X-Factor Stretch, 클럽변인과 전체비거리(total length)와의 상관관계)

  • Park, Hye-Lim;So, Jae-Moo;Kim, Jai-Jeong
    • Korean Journal of Sport 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.

Development of a Video Caption Recognition System for Sport Event Broadcasting (스포츠 중계를 위한 자막 인식 시스템 개발)

  • Oh, Ju-Hyun
    • 한국HCI학회:학술대회논문집
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    • pp.94-98
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    • 2009
  • A video caption recognition system has been developed for broadcasting sport events such as major league baseball. The purpose of the system is to translate the information expressed in English units such as miles per hour (MPH) to the international system of units (SI) such as km/h. The system detects the ball speed displayed in the video and recognizes the numerals. The ball speed is then converted to km/h and displayed by the following character generator (CG) system. Although neural-network based methods are widely used for character and numeral recognition, we use template matching to avoid the training process required before the broadcasting. With the proposed template matching method, the operator can cope with the situation when the caption’s appearance changed without any notification. Templates are configured by the operator with a captured screenshot of the first pitch with ball speed. Templates are updated with following correct recognition results. The accuracy of the recognition module is over 97%, which is still not enough for live broadcasting. When the recognition confidence is low, the system asks the operator for the correct recognition result. The operator chooses the right one using hot keys.

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