• 한국운동역학회지
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• 제23권3호
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• pp.219-223
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• 2013

The purpose of the study was to investigate the effects of gymnasts shoes on risk factors of anterior cruciate ligament injuries during drop-landing followed by vertical jump in female gymnasts. Thirteen female gymnasts were recruited and performed randomly drop-landing followed by vertical jump in height of her knee with and without shoes. Kinematics and ground reaction data were collected to estimate the anterior cruciate ligament injuries risk factors. Data were analyzed with paired samples t-test with Bonferroni correction. Female gymnasts with shoes showed more reduced thigh maximum adduction angle, and knee maximum extension moment than without shoes. Female gymnasts with shoes showed more increased shank maximum abduction angle than without shoes. In conclusion, Female gymnasts with shoes reduced anterior cruciate ligament injuries risk factors.

• 한국운동역학회지
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• 제20권1호
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• pp.49-55
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• 2010

The purpose of the study was to analyze kinetic factors required to the three-point jump shot of the basketball games through 3-D analysis and ground reaction force(GRF) analysis. Six university male players participated in this study. The results of the study were showed that (1) resultant velocity in the center of mass(COM) was $0.84{\pm}0.27\;m/s$ since a player didn't shot a ball in the highest peak and shot ball at the moment of going up forward and vertical movement. Therefore, it is necessary to find a proper timing to shot a ball; (2) the angular velocity was largely increased in upper arm and fore arm out of the upper-limb segments and the hands had the largest angular velocity since the body is in a fixed situation and angular speed is rapidly increased by the wrist' snap with the rapid movement of upper arm and forearm at the time of release a ball; (3) it is judged that a player can shot a ball at the accurate and high release point when the player collects power vertically to the maximum by keeping GRF to the right and the rear in a proper way and by keeping the body's balance so that a large power may not be dispersed.

• 한국운동역학회지
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• 제17권3호
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• pp.23-29
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• 2007

The purpose of this study were to investigate the differences between female and male basketball players in knee neuromuscular biomechanical factors during basketball rebound jump. Twelve high school female ($17.9{\pm}0.8years$) and twelve male ($19.0{\pm}1.6years$) basketball players rebound jumped for maximal vertical height to sufficiently stress the anterior cruciate ligament. Kinematic and ground reaction data were collected and combined with inverse dynamics to estimate the knee extensor and abductor torque. The EMG data from the biceps femoris and rectus femoris was used to estimate the ratio of quadriceps muscle activity. Female athletes showed more reduced knee flexion at foot contact, more increased knee abduction, extensor and abductor knee joint torque at foot contact, and quadriceps ratio at stance phase than those of male athletes. In conclusion, Female athletes showed differences in knee neuromuscular biomechanical factors than male athletes during basketball rebound jump.

• 소음진동
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• 제6권4호
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• pp.439-446
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• 1996

This paper introduces a newly designed pendulum system that enables the more accurate boservation of dynamic behaviour arising from both horizontal and vertical(i.e. two dimension) excitation. First, experiments were carried out to examine the frequency responses of the devised pendulum system. Interestingly, experimental results for the three excitation angles of 22, 32 and 48 degree show 'new' jump phenomena. For the further understanding of these phenomena, experimental investigationhas been made to identify the equation of motion of the pendulum system from experimental data. This attempt has revealed that the viscous, coulomb and aerodynamic damping factors are involved in the equation of motion. By applying the Ritz averaging method to the equation, it becomes apparent that the jumping phenomena of the pendulum system in this work is more theoretically understood.

• 한국수자원학회논문집
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• 제56권spc1호
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• pp.1049-1058
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• 2023

보와 저낙차 댐과 같은 하천횡단구조물을 통과하는 흐름은 도수 현상을 동반하는 급변류가 지배적이다. 구조물 하류에서 도수로 인한 유속과 수면의 강한 비정상성은 수공구조물의 안정에 영향을 줄 수 있다. 특히, 높은 Froude 수 조건에서 발생하는 정상도수는 공기연행이 현저하게 발생하여 흐름 특성은 더욱 복잡해진다. 이 연구에서는 Froude 7.3 조건에서 발생하는 정상도수를 모의하기 위해서 큰와모의 기법과 하이브리드 VoF 기법을 이용한 수치모의를 수행하였다. 수치모의 결과는 구조물 하류 바닥면에서 계측된 순간최대압력과 시간평균압력 분포를 유사하게 재현하는 것으로 나타났다. 단, 구조물 직하류에서의 순간최소압력 분포는 대상으로 하는 실험 계측값과 반대의 양상을 보이지만, 유사한 다른 시험과는 같은 양상을 보임으로써 본 연구에서 수행한 수치모의는 합리적으로 압력변동을 예측하는 것으로 판단된다. 도수 중앙부에서의 연직방향 유속분포와 공기농도분포는 유사한 조건의 실험 결과들과 자기상사성을 보이면서 양호하게 일치하는 것으로 나타났다. 이러한 결과는 본 연구에서 적용한 큰와모의 기법과 하이브리드 VoF 기법이 높은 Froude 수 조건에서 강한 공기연행을 동반하는 도수현상을 양호하게 재현할 수 있음을 보여준다.

• 한국운동역학회지
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• 제18권4호
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• pp.209-216
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• 2008

본 연구의 목적은 대학 세단뛰기 선수들의 각 지지국면에서 충격력과 운동학적 변인을 조사하는 것이다. 실제 경기 상황을 촬영하였고 경기력이 올림픽 B기준을 통과한 선수를 대상으로 영상분석 방법을 이용하여 자료를 산출하였다. 본 연구의 결과는 스텝 이륙과 착지 평균 거리가 홉과 점프의 이륙과 착지 거리보다 더 긴 것으로 조사되었다. 홉 이륙거리를 길게 하고 스텝의 착지거리를 줄여야 하는 것으로 조사되었다. 세단뛰기 각 국면에서 이륙과 접지순간에 나타나는 평균 신체중심의 높이 변화 패턴은 이륙순간에 medium-low-high이였고 접지순간에는 홉과 스텝이 동일한 패턴 이였다. 홉의 도약각도는 선행연구 보다 2도 더 높은 것으로 나타났고, 평균 충격력은 수평방향으로 체중에 약 0.6배에서 0.7배 범위에 있었고 수직방향으로는 약 2.8배에서 3.0배의 범위에 있는 것으로 나타났다.

• 한국운동역학회지
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• 제17권1호
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• pp.135-144
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• 2007

The purpose of this study was to identify the effect of the subtalar sling ankle taping, by measuring changes in peak plantar pressure and subtalar angle during jump landing and walking in healthy subjects with subtalar sling ankle taping applied of the ankle joint. Fifty healthy subjects(8 males and 7 female, aged 22 to 25) were randomly divided into a participated in this study. They were free of musculoskeletal injury and neurologic deficit in lower extremity. The subjects were asked to perform 5M walking and single leg jump landing by under the guidance of physical therapists. Subtalar motions were typically measured as the angle made between the posterior aspect of the calcaneous and the posterior aspect of the lower leg during walking with taping or not. This measurement were made using a video system (30Hz sampling rate, rectified 60 Hz sampling rate). At the same time, peak lateral and vertical pressure were investigated using pressure distribution platforms(MatScan system) under foot during walking and single leg jump landing with taping or not. Statistical analysis was done by paired t-test and intraclass correlation coefficient [ICC(3.1)], using software SPSS. We have recently demonstrated significantly altered patterns of subtalr joint and peak plantar pressure when applied subtalar sling ankle taping(p<.05). Inversion angle of subtalar joint significantly decreased with taping(p<.05). The result suggest that pressure patterns observed in subjects are likely to result due to significant decrease in stress on ankle joint structures during jump landing and walking. Also, the result that the subtalar sling ankle taping procedure provides greater restiction of motion associated with ankle inversion. However, this study involved asymptomatic subjects without history of ankle inversion injury, further research is needed to assess the motion restraining effect of the subtalar sling ankle taping in subjects with lateral ankle instability.

• 한국운동역학회지
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• 제16권4호
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• pp.39-47
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• 2006

This study long jump action to each situation on a chessboard and section of sight disabled person and normal person through third dimension reflex analysis mechanical special quality because do comparative analysis sight disabled person's exercise ability and technology structure of action that run understand. As can do better without danger of injury map and training of exercise item that action that run is included, do offer of pabulum by purpose. Through this study, conclusion is as following. 1. Sight disabled persons' long jump average recording (121.84cm) showing normal persons' average recording (259.27cm) and much differences, show that motion of body is not big to Touch-down from Ready action. 2. Each phase body center composition(r) average speed displayed result that it is more meaning more than Each phase time required. 3. Began in line carriage without body back stretching in 1 situation on Event one are sight disabled persons. Was expose that do not bend enough knee and ankle than normal person in Event two. Was expose that body is not drooped for surface of land in Event three, and knee and ankle were expose that do not unfold easily than normal person. Was expose that do not bend enough on Touch-down knee by relation that can not grasp position of the floor in Event four. 4. When taking off, the average of horizontal speed of body center are 1.80m/sec for blind people and 3.53m/sec for the normal. In this connection, the study shows that the difference of horizontal speed between the blind and the normal is bigger than difference of vertical speed, which are 1.56m/sec for the blind and 1.98m/sec for the normal. Also, composite speed also shows us big difference between 2.41m/sec of the blind and 4.07m/sec of the normal. The speed body center of take-off was expose that average adjuster are big width of deceleration than average - beginning disabled person's average by 2.23m/sec - 1.71m/sec in the vertical speed. 5. If examine change of high and low for z Sign of right hand, change of high and low showed as is small than normal person is sight obstacle, and all hand movements are small and was expose that do not use enough reaction of body as well as in ready action.

• 한국운동역학회지
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• 제13권1호
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• pp.39-50
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• 2003

The purpose of this experiment was to find out the stages of result of specific character for Horse Vaulting Yeo motion To put the Yeo movement in process, we needed a gymnastics athlete C height of 165cm, weight of 62kg, age of 32, personal history of 21 years, and tested the athlete 5 times of motion training, and picked out the 2 best motion and analyzed it. Athletic reason is vertical motion, time uses, horizontal motion, distance, speed, and analyzed many other reasons as a result, and finally ended up with this conclusion. 1. After the take off on the board horizontal speed gradually decreased However, reverse of that, it showed that vertical speed increased. 2. While contacting the Horse Vaulting, horizontal speed decreased and vertical speed kept on increasing. Taking off Com the Horse Vaulting, horizontal, showing short time of training, 3m vertical height is shown after using Yeo motion at the peak of second fly jump. 3. While contacting the Horse Vaulting, both arms were showing the flection shape Especially this is also while contacting the Horse Vaulting, left arm was showing $90^{\circ}$ angle, and this has happened between the process of transition period of fast horizontal speed to vertical speed. 4. While contacting the Horse Vaulting, perfect blocking of the left arm must be complete for the right arm to have the perfect blocking as well.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제24권1호
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• pp.103-119
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• 2020

In this work, the hydromagnetic and thermal characteristics of natural convection flow in a vertical parallel plate micro-porous-channel with suction/injection is analytically studied in the presence of Hall current by taking the temperature jump and the velocity slip at the wall into account. The governing equations, exhibiting the physics of the flow formation are displayed and the exact analytical solutions have been obtained for momentum and energy equations under relevant boundary conditions. The impact of distinct admissible parameters such as Hartmann number, Hall current parameter, permeability parameter, suction/injection parameter, fluid wall interaction parameter, Knudsen number and wall-ambient temperature ratio on the flow formation is discussed with the aid of line graphs. In particular, as rarefaction parameter on the micro-porous-channel surfaces increases, the fluid velocity increases and the volume flow rate decreases for injection/suction.