• Steel and Composite Structures
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• 제46권5호
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• pp.669-672
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• 2023

In this research, the researcher has examined the factors affecting the movement of the soccer ball and will show that the effects such as air resistance, altitude above sea level, wind, air pressure, air temperature, air humidity, rotation of the earth, changes in the earth's gravitational acceleration in different areas. It, the geographical length and latitude of the launch point, the change of gravitational acceleration with height, the change of pressure with height, the change of temperature with height and also the initial spin (Magnus effect) affect the movement of projectiles (especially soccer ball). We modelled th ball based on shell element and derive the motion equations by energy method. Finally, using numerical solution, the wave of the ball is studied. The influences of various parameters are investigated on wave propagation of the ball. Therefore, in short, it can be said that the main factors that play a major role in the lateral deviation of the hit ball are the initial spin of the ball and the wind.

• Geomechanics and Engineering
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• 재33권6호
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• pp.529-542
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• 2023

Wave propagation with high transverse deflection could affect the stability of the ball in its trajectory. For low stiffness balls similar to soccer and volleyball balls, the waves are more noticeable in comparison to other balls like ping-pong ball. On the other hand, the soccer balls are under heavy impact loads from shoots and contacting different objects in the field. The maximum recorded speed of a soccer ball after kicking is the 211 km/hr and the average maximum speed is around 112 km/hr. Therefore, in such speeds the aerodynamic forces become important which are directly related to geometrical shape of the ball. In this regard, the wave propagation in soccer ball is examined in the current study using large deformation shear deformable formulations. Classical relations of stress-strain components are taken into consideration along with minimum total energy principle. The final derived relations were solved by using harmonic differential quadrature method. The results are generally presented ion term of phase velocity as function of different influencing parameters of the materials, geometry and mass of the ball.

• 대한물리의학회지
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• 제13권4호
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• pp.85-94
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• 2018

PURPOSE: This study was conducted to determine the effects of therapeutic exercise on range of motion (ROM), the manual muscle test (MMT), functional movement screen (FMS) and radiological evaluation in a youth football player with football-specific anterior pelvic tilt (APT). METHODS: The subject of this case report was a 12-year-old youth football player, who presented with football-specific APT. Therapeutic exercise consisted of hamstring stretch, prone hip extension, abdominal crunch, bridging with isometric hip abduction, plank exercise with posterior tilt and posterior pelvic tilting exercise using a swiss-ball for 40 min/day, twice a week for 8-weeks. ROM, MMT, FMS (deep squat, hurdle step, inline lunge, shoulder mobility, active straight-leg raise, rotary stability and trunk stability push-up) and radiographs (lumbar lordotic and sacral horizontal angle) were analyzed before and after week 8 of therapeutic exercise. RESULTS: The ROM, MMT, and FMS increased and the lumbar lordotic angle and sacral horizontal angle improved after 8-weeks of therapeutic exercise. CONCLUSION: The results of this case report suggest that therapeutic exercise improves ROM, MMT and radiography associated parameters in youth football players with football-specific APT. These findings have clinical implications for therapeutic exercise in youth football players with football-specific APT.

• 대한정형외과스포츠의학회지
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• 제5권2호
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• pp.94-99
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• 2006

축구는 유산소와 무산소운동이 혼합된 형태의 구기이고, 축구에서 필요로 하는 신체 능력은 지구력, 근력, 스피드, 순발력 및 유연성 등이 있으며, 이중 골 결정력에 영향을 미치는 인자는 순발력이 필수적인 것으로 알려져 있다. 그러나, 최근 축구의 경향을 보면, 스피드를 중시하는 미드필더의 강한 압박을 기본으로 하는데, 따라서 체력적인 요소 중에서 스피드에 더 많은 관심이 모아지고 있다. 이런 스피드의 요소에 대하여 자세히 알아보도록 하자.

• 산업경영시스템학회지
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• 제38권2호
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• pp.101-107
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• 2015

Modern football has transformed into a scientific football based on data. With this trend, various methods for tactics studies and outcome prediction have been developed on the perspective of data analysis. In this paper, we propose a structural equation model for football game. We analyze critical factors that affect to the winning of game except psychological parts and the causal relationship between latent variables and observed variables is statistically verified through the proposed structural equation model. The results show that the Passing ability and the Ball possession affect to the Attack ability, and consequently it has a positive impact on the winning of game.

• Communications for Statistical Applications and Methods
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• 제8권2호
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• pp.557-564
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• 2001

The objective of he study is to record the real conditions along with the soccer ball that is, each player's ball keeping time, the number football keeping, accuracy of passing to other player, direction, etc., on a real-time basis, measure them in numbers and get necessary analyzed output as much as one needs. The study consists of the following stages: (1) Record the data by drawing through Visual Interface on a real-time basis; (2) Graphic windows to display the recorded data item by item in graphic; (3) Form windows to display the individual or team scores anytime when needed; (4) Windows to display the analyzed data in visualized form. The effect of the study is threefold: (1) It inputs all the game-related data on a real-time basis, which was impossible before and shows analyzed contents during the game enabling each tea manager o use; (2) In cse of TV broadcasting or newspaper articles, it explains objectively the situations of he game to the TV viewers or readers; (3) After the game, it provides importance information on each team's playing ability and individual player's technical improvement through data analysis.

• 아시안잔디학회지
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• 제20권2호
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• pp.203-211
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• 2006

본 연구는 천연잔디, 인조잔디 및 맨땅 축구장이 축구 경기력에 미치는 영향을 구명하고자 하였다. 천연잔디 축구장은 한지형 잔디(켄터키 블루그래스 80%+퍼레니얼 라이그래스 20%)와 중엽형 한국잔디로 조성된 축구장이며, 인조잔디 축구장은 코니그린 $DV5000^{TM}$으로 조성하였고 맨땅 축구장은 마사토로 조성되었다. 축구 경기력 분석을 위한 볼 구름거리(m)와 수직 볼리바운드(m)는 2005년과 2006년 건국대학교 스포츠과학타운에서 조사하였다. 본 실험에 사용된 공은 한국축구협회(Korea Football Association)에서 공인된 Hummel Air Vision #1을 사용하였고 공기압은 1.0 1bs를 유지하였다. 볼 구름거리는 맨땅 축구장(13.6m) > 인조잔디 축구장(11.4m) > 한지형 잔디축구장(7.8m) > 한국잔디 축구장(4.7m) 순으로 길었다. 또한 볼 구름거리는 잔디의 사용빈도가 적을수록, 잔디의 직립정도가 강할수록, 잔디의 밀도가 높을수록 짧아지는 경향이었다. 수직 볼리바운드 역시 맨땅 축구장(1.0m) > 인조잔디 축구장(0.98m) > 한지형 잔디 축구장(0.68m) > 한국잔디축구장(0.4m) 순으로 높았다. 수직 볼 리바운드는 잔디의 사용빈도가 적을수록, 잔디의 직립정도가 강할수록, 잔디의 밀도가 높을수록 낮아지는 경향이었다. 표준관리가 되는 한지형 잔디 축구장은 조성연수에 따른 볼 구름거리와 수직 볼 리바운드에 미치는 영향이 적었다. 반면 표준 관리가 하지 않은 한국잔디 축구장은 오래 될수록 볼 구름거리는 길어졌고 수직 볼 리바운드 역시 높았다.

• 한국운동역학회지
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• 제13권1호
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• pp.139-153
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• 2003

The purpose of the study was to present technical guidance about the field goal kicking motion in American football for novices. For this purpose, kinematic analysis on the field goal kicking motion of two skilled players and two unskilled players was carried out. The following conclusions were made: 1. In comparison on the total elapsed time of the kicking, there were no significant differences between two groups. The progressing time from BP event to impact among experts group, however, took 0.141 second less than that of novices group. 2. The experts group showed right hip rotatier horizontally toward the targeted ball fixing left hip as the axis. On the other hand, the novices group didn't use the left hip as the axis in the kicking motion. 3. At the impact of kicking the ball, regarding with the distance of the ball and the supporting leg, the right and left distance of experts was 3.45cm longer than that of novices, the front and the rear distance of experts was 5.14cm shorter than novices. 4. At the impact, experts' initial velocity of the targeted ball was $5.27^m/s$ faster than novices', besides experts' incidence angular displacement was $3.78^{\circ}$ larger than novices'. 5. After BP event, experts showed a stable movement maintaining flexion and extension at left hip joint and knee joint. On the other hand, for novices, the angle of the left lower extremities became larger. 6. Experts showed the efficient flexion and extension of the hip joint and the knee joint during following procedure in the whole event of the kicking motion. At the BP event, the right knee joint angle of novices was $11.46^{\circ}$ larger than that of experts. However, the duration of the impact event and FT event among, novices had less extension of knee joint than experts. 7. At the 2nd phase, for both of the groups, the angular velocity of the knee joint drastically increased as the angular velocity of hip joint decreased. However, only novices showed the largest negative angular velocity at the impact.

• Advances in nano research
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• 제17권1호
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• pp.51-59
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• 2024

Nanotechnology, the science of manipulating matter at the nanoscale, offers remarkable opportunities for innovation across various fields. Nanomaterials, which form the cornerstone of advanced materials, drive forward new ideas and groundbreaking applications. In the textile industry, traditional antibacterial and antifungal garments are typically treated with chemical compounds to inhibit bacterial growth. However, these treatments often lack durability, losing effectiveness after multiple washes. To address this limitation, the application of green nanotechnology in developing high-performance textiles emerges as a promising solution. This study explores the integration of nanocomposites into the polymer layers of footballs to enhance their stability and performance. By embedding nanoparticles within the polymer matrix, the durability and resilience of the footballs are significantly improved, leading to better control and performance on the field. This innovative approach not only extends the lifespan of the footballs but also provides economic advantages by reducing the frequency of replacements. Additionally, the enhanced stability contributes to a more consistent and reliable playing experience, promoting improved safety and performance for athletes.

• 한국운동역학회지
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• 제13권1호
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• pp.155-171
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• 2003

The purpose of this study was to analyze the kinematic variables of over head kick(OHK) in soccer with three dimensional analysis technique and show the kinematic characteristics of it. The 7 subjects were university football player who have been playing football more than 7 years. The OHK was filmed on 16mm video camera(30frame/sec.) kinematic variables were temporal, postures, and COG(center of gravity). The mean values and the standard deviation for each variables were obtained and used as basic factors for examining characteristics of OHK. The results of this analysis were as follows : Temporal variables : The total time elapsed(TE) of OHK was $0.95{\sim}1.14sec$, the 1st phase was 0.35sec., 2nd phase was 0.46sec., and 3rd phase was 0.22sec.. Posture variables : When subjects performed OHK at the impact event, the ankle and knee angle of kicking foot were more extend than supporting foot. but the hip angle of supporting foot were more extend than kirking foot. Moving distance of the center of mass of the both foot. When subject performed OHK at the impact event, the range of distance on mediolateral direction aspect into right left shoulder line, anteroposterior direction aspect was $20.9{\pm}10.5cm$, vertical direction aspect was $92.3{\pm}19.9cm$. Angular velocity : the faster angular velocity of knee ankle on the kicking foot pew form jump position to landing position, the faster velocity of ball became. C. O. G. variables. When subject performed OHK at the impact event, upper part of the body was getting lower, lower part of the body was getting higher.