• Title, Summary, Keyword: Step landing

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Analysis on Biomechanical Differences in Lower Limbs Caused by Increasing Heart Rates During Drop-landing (드롭랜딩 시 심박수 증가에 따른 하지의 생체역학적 차이 분석)

  • Hong, Wan-Ki;Kim, Do-Eun
    • Korean Journal of Sport Biomechanics
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    • v.25 no.2
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    • pp.141-147
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    • 2015
  • Objective : This study aimed to understand how increased heart rates at the time of drop landing during a step test would affect biomechanical variables of the lower extremity limbs. Background : Ballet performers do more than 200 landings in a daily training. This training raises the heart rate and the fatigability of the lower extremity limbs. Ballet performance high heart rate can trigger lower extremity limb injury. Method : We instructed eight female ballet dancers with no instability in their ankle joints(mean ${\pm}$ SD: age, $20.7{\pm}0.7yr$; body mass index, $19.5{\pm}1.2kg/m^2$, career duration, $8.7{\pm}2.0yr$) to perform the drop landing under the following conditions: rest, 60% heart rate reserve (HRR) and 80% HRR. Results : First, the study confirmed that the increased heart rates of the female ballet dancers did not affect the working ranges of the knee joints during drop landing but only increased angular speeds, which was considered a negative shock-absorption strategy. Second, 80% HRR, which was increased through the step tests, led to severe fatigue among the female ballet dancers, which made them unable to perform a lower extremity limb-neutral position. Hence, their drop landing was unstable, with increased introversion and extroversion moments. Third, we observed that the increasing 80% HRR failed to help the dancers effectively control ground reaction forces but improved the muscular activities of the rectus femoris and vastus medialis oblique muscles. Fourth, the increasing heart rates were positively related to the muscular activities of the vastus medialis oblique and rectus femoris muscles, and the extroversion and introversion moments. Conclusion/Application : Our results prove that increased HRR during a step test negatively affects the biomechanical variables of the lower extremity limbs at the time of drop landing.

Evaluation of Consistency on Kinematic Factors in Women Javelin Throw (여자 창던지기 운동학적 요인의 일관성 평가)

  • Hong, Soon-Mo;Lee, Young-Sun
    • Korean Journal of Sport Biomechanics
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    • v.17 no.4
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    • pp.65-71
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    • 2007
  • The purpose of this study was to investigate variability of kinematic factors affecting the record in women's javelin throwing. For this study, 8 female-javelin thrower participated in this experiment. The three digital video cameras (Sony, 120x) were used to record motions. Kwon3D 2.1 was used to process data and they were analyzed with Excell for factors. The sampling rate of a camera was 60Hz and shutter speed of a camera was 1/1000sec. The coordinate data were filtered using a fourth-order Butterworth low pass filtering with an estimated optimum cut-off frequency of 6Hz. The results were as follows: 1. From cross step to landing of delivery, the average velocities of CoM of non-dominant athletes were greater than dominant athletes and those of CoM of non-dominant athletes less than dominant athletes, but at release dominant athletes had a lower average velocity and a variability than non-dominant athletes. 2. From cross step to landing of delivery, the average throwing velocities and variabilities of a javelin of dominant athletes were greater than dominant athletes, but at release, dominant athletes had a higher velocity than dominant athletes and had a equal variability. 3. At every events, a forward or backward angles and variabilities of non-dominant athletes were greater than dominant athletes. 4. From cross step to landing of delivery, dominant athletes' elbow average angles were greater than non-dominant athletes and the variabilities of latter less than non-dominant athletes, but at release dominant athletes' variabilities were smaller than non-dominant athletes. 5. At landing of delivery, dominant athletes' knee average angles and variabilities of a supporting foot were a greater than non-dominant athletes, and at release, dominant athletes' knee average angles was a greater but variabilities less than non-dominant athletes. In conclusion, the dominant threw javelins fast while having stable postures and the range of elbow's angle large.

Effects of Landing Height and Knee Joint Muscle Fatigue on Movement of the Lower Extremity during Cutting After Landing (착지 높이와 무릎관절 근육 피로가 착지 후 방향 전환 동작 시 하지관절의 움직임에 미치는 영향)

  • Kim, You-Kyung;Youm, Chang-Hong
    • Korean Journal of Sport Biomechanics
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    • v.25 no.3
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    • pp.311-322
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    • 2015
  • Objective : The purpose of this study was to investigate the effects of landing height and knee joint muscle fatigue on the movement of the lower extremity during cutting after landing. Method : Subjects included 29 adults (age: $20.83{\pm}1.56years$, height: $172.42{\pm}9.51cm$, weight: $65.07{\pm}10.18kg$). The subjects were asked to stand on their dominant lower limb on jump stands that were 30 and 40 cm in height and jump from each stand to land with the dominant lower limb on a force plate making a side step cutting move at a $45^{\circ}$ angle with the non-dominant lower limb. The fatigue level at 30% of the knee extension peak torque using an isokinetic dynamometer. Results : The results showed that the difference of landing height increased maximum range of motion and angular velocity of hip, knee, and ankle joints in the sagittal plane, and in the angular velocity of motion of the hip joint in the sagittal plane. The maximum range of motion of the knee joint in the sagittal plane and the frontal plane decreased on landing from both heights after the fatigue exercise. The angular velocity of the hip joint in the sagittal plane, and the maximum range of motion of the hip joint in the transverse plane decreased for both landing heights after the fatigue exercise. The angular velocity of the hip joint in the frontal plane decreased for the 30 cm landing height after the fatigue exercise. On the other hand, the angular velocity and maximum range of motion of the ankle joint in the sagittal plane for both landing heights, and the angular velocity and maximum range of motion of the ankle joint in the frontal plane increased on landing from the 40 cm height after the fatigue exercise. Conclusion : Different landing heights of 30 and 40 cm and 30% fatigue of peak torque of knee extensor found a forefoot and stiff landing strategy, when cutting after landing. These results might be due to decline in the shock absorption capability of the knee joint and the movement capability related to cutting while increasing the contribution of the ankle joint, which may cause increased ankle joint injuries.

Transient Responses of an Airplane Taking off from and Landing on a Very Large Floating Structure in Regular Waves (규칙파중 항공기 이.착륙시 초대형 부유식 해양구조물의 천이 응답 해석)

  • 신현경;이호영;임춘규;강점문;윤명철
    • Journal of Ocean Engineering and Technology
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    • v.15 no.1
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    • pp.26-30
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    • 2001
  • Up to now, Most studies of hydroelasticity are about frequency domain analysis. Those aren't suited for analysis of the landing take-off, and dropping of aircraft on a structure. So, the concern of this paper is the transient behavior of a VLFS subjected to dynamic load, induced by airplane landing and take-off. To predict the added mass, damping coefficient, and wave exciting force, the source-dipole distribution method was used in the frequency domain. The responses are accomplished by using the FEM scheme. A time domain analysis method is based on the Newmark β method to pursue the time step procedure, taking advantage of memory effect function for hydrodynamic effects.

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Kinematic Analysis of Men's Triple Jump at IAAF World Championships, Daegu 2011 (2011 대구세계육상선수권대회 남자 세단뛰기 경기의 운동학적 분석)

  • Woo, Sang-Yeon;Seo, Jung-Suk;Kim, Ho-Mook;Kim, Yong-Woon;Choi, Sung-Bum;Nam, Ki-Jeong
    • Korean Journal of Sport Biomechanics
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    • v.21 no.5
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    • pp.611-619
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    • 2011
  • The purpose of this study was to analyze the kinematics of the men's triple jump at the 2011 Daegu World Championships by comparing the results to those at the 2009 Berlin World Championships. The kinematic data were gathered from two steps before take off to the landing using a seven panorama system, and these data were divided into 3 phases for 8 participants. The average jump for the finalists was longer in the Daegu championships (17.46 m) than in the Berlin championships (17.28 m). The longest jump record was increased by 23 cm. The step was the longest at 36% of the total distance, followed by the hop at 30% and the jump at 34%. The first and third phases were substantially longer than the second phase (the step). The horizontal speed at take-off increased in the order hop, step, and jump. Overall, in comparison with the results from Berlin, the horizontal velocity increased, the vertical velocity decreased, and the landing angle decreased.

Transient Responses of an Airplane Taking off from and Landing Very Large Floating Stricture in Waves (항공기 이 .착륙 시 초대형 부유식 해양구조물의 시간 영역 응답 해석)

  • 신현경;이호영;임춘규;강점문;윤명철
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.63-67
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    • 2000
  • Up to this day, Most studies of hydroelasticity are inclined to frequency domain atnlysis. Thos amlysis Q the landing, take-4, and dropping of airaqft on a structure. So, the concern of this prrper is a tra a VLFS subjected to dymmic lazd induced by airplane larndirrg and take-off. To predict added mass, dampr exciting force, the source-dipole distribution method were used The responses are accomplished by Fdoimain analysis method is based on Newmark $\beta$ method to pursuit time step pnzcedure taking advantage function for hvdrodvnumic effects.

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The Kinematics Analysis of Round-off at end of Beam-salto Backward Stretched with Step-out to Cross on Balance Beam (평균대 도움 짚고 몸 펴 뒤 공중 돌아 오르기 동작에 대한 운동학적 분석)

  • Kim, Young-Ran
    • Korean Journal of Sport Biomechanics
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    • v.13 no.3
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    • pp.99-116
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    • 2003
  • The purpose of this study was to kinematics factors on during round-off at end of beam-salto backward stretched with step-out to cross on balance beam. Four elite female gymnastics players participated as subject of this study. The methods of this study was analyzed using three dimentional analysis. The results and conclusion of this paper is obtained as follows ; 1. The phase of time was the most short time in board touch down phase and board take-off phase. Also, it was shown a more long time in total time compared to previous study. 2. The horizontal displacement of each phase was shown the most high levels in balance beam landing. The vertical displacement was display a non-linearity increase in board take-of phase, and it was shown the most high levels in vertical displacement during landing of balance beam. 3. The horizontal velocity of each phase was shown the most high levels in board touch down, and it was display a gradually decreased levels because flight during board take-of. The resultant velocity of CG on each phase was shown the most high levels in board touch down and board take-off. 4. The angle of hip joint was shown the most high levels as performed a motion in extension state during board take-off, and the angle of knee joint was display a increased levels because of flight cause body extension in board take-off. Also the angle of ankle joint was shown a increasing levels during board take-off. Considering to this results, it is suggest that the change of kinematics factors in board touch down and board take-off is key role on the effective board control.

Elemental techniques for automated size sorting system considering problems and status of sorting process of ark shell (Scapharca subcrenata) (새꼬막의 선별과정 현황과 문제점을 고려한 자동화 선별 시스템 요소기술)

  • JEONG, Seok-Bong;HWANG, Doo-Jin;YOON, Eun-A;MIN, Eunbi;CHOI, Byeong-Dae;JUNG, Yong-Gil
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.53 no.3
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    • pp.256-265
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    • 2017
  • Seafood is attracting attention as a future food industry. In recent years, the demand for fishery equipment of mechanization, automation, and unmanned was increased due to the environment affected by seafood processing, stricter regulations on safety, decline and aging of fishery worker. Ark shell (Scapharca subcrenata) was being produced in many steps in the production process. The process has been made such as collection-landing-washing-first sort (goods/non-goods)-transports-second sort (size). It was undergone first and second steps by delivering to the consumer. Here, the first step is to sort goods to collection and the second step is to sort by size. The fishery workers need ten people in first step and six people in second step. The workload of one hour per kg is 4,247 kg/h in first step and 2,213 kg/h in second step. In addition, the goods ratio by work process was 79% in first step and 98% in the second step. In this process, a lot of fishery worker and working time is needed. Therefore, this study developed elemental techniques for an automated size sorting system considering the working process problem, time and situation for washing and sorting of ark shell.

Lifting off simulation of an offshore supply vessel considering ocean environmental loads and lifting off velocity

  • Jeong, Dong-Hoon;Roh, Myung-Il;Ham, Seung-Ho
    • Ocean Systems Engineering
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    • v.5 no.3
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    • pp.181-198
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    • 2015
  • An OSV (Offshore Support Vessel) is being used to install a structure which is laid on its deck or an adjacent transport barge by lifting off the structure with its own crane, lifting in the air, crossing splash zone, deeply submerging, and lastly landing it. There are some major considerations during these operations. Especially, when lifting off the structure, if operating conditions such as ocean environmental loads and lifting off velocity are not suitable, the collision can be occurred due to the relative motion between the structure and the OSV or the transport barge. To solve this problem, this study performs the physics-based simulation of the lifting off step while the OSV installs the structure. The simulation includes the calculation of dynamic responses of the OSV and the structure, including the collision detection between the transport barge and the structure. To check the applicability of the physics-based simulation, it is applied to a problem of the lifting off step by varying the ocean environmental loads and the lifting off velocity. As a result, it is confirmed that the operability of the lifting off step are affected by the conditions.

Kinematic Analysis of Women's Triple Jump at IAAF World Championships Daegu 2011 (2011 대구세계육상선수권대회 여자 세단뛰기 경기의 운동학적 분석)

  • Woo, Sang-Yeon;Seo, Jung-Suk;Kim, Ho-Mook;Nam, Ki-Jeong;Choi, Sung-Bum;Kim, Yong-Woon
    • Korean Journal of Sport Biomechanics
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    • v.21 no.5
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    • pp.621-629
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    • 2011
  • The purpose of this study was to analyze the kinematics of the women's triple jump event at the 2011 Daegu World a Chmpionships by comparing them to those of the 2009 Berlin World Championships. The kinematic data were gathered from two steps before take off to the landing using a 7-camera panorama system. The data were then divided into 3 phases for each of the 8 participants. Similar average results were found the final contestants in the Daegu and Berlin championships, 14.58 m and 14.51 m, respectively. The first step had a relatively short length percentage (29%) compared to the hop and jump (36% and 35%, respectively). At the take off, the horizontal velocity was the lowest for the step, followed by the hop and jump. These results were different from the results for the men, who had an order of hop, step, and jump. Overall, in a comparison of the Daegu and Berlin participants, the vertical speed at take off for the three events was reduced compared to the horizontal speed.