• 한국전문물리치료학회지
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• 제31권1호
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• pp.29-39
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• 2024

Background: Landing from a step or stairs is a basic motor skill but high incidence of lateral ankle sprain has been reported during landing with inverted foot. Objects: This study aimed to investigate the effect of landing height and visual feedback on the kinematics of landing and supporting lower limbs before and after the touch down and the ground reaction force(GRF)s. Methods: Eighteen healthy females were voluntarily participated in landing from the lower (20 cm) and the higher (40 cm) steps with and without visual feedback. To minimize the time to plan the movement, the landing side was randomly announced as a starting signal. Effects of the step height, the visual feedback, or the interaction on the landing duration, the kinematic variables and the GRFs at each landing event point were analyzed. Results: With eyes blindfolded, the knee flexion and ankle dorsiflexion on landing side significantly decreased before and after the touch down. However, there was no significant effect of landing height on the anticipatory kinematics on the landing side. After the touch down, the landings from the higher step increased the knee flexion and ankle dorsiflexion on both landing and supporting sides. From the higher steps, the vertical GRF, anterior GRF, and lateral GRF increased. No interaction between step height and visual feedback was significant. Conclusion: Step height and visual feedback affected the landing limb kinematics independently. Visual feedback affected on the landing side while step height altered the supporting side prior to the touch down. After the touch down, the step height had greater influence on the lower limb kinematics and the GRFs than the visual feedback. Findings of this study can contribute to understanding of the injury mechanisms and preventing the lateral ankle sprain.

• 한국운동역학회지
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• 제25권2호
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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.

• 한국운동역학회지
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• 제17권4호
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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.

• 한국운동역학회지
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• 제25권3호
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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.

• 한국해양공학회지
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• 제15권1호
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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.

• 한국운동역학회지
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• 제21권5호
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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.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 추계학술대회 논문집
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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.

• 공연문화연구
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• 제41호
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• pp.219-255
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• 2020

본고는 빅터 메어(Victor H. Mair)의 용어 'Painting and performance'에서 촉발되었다. 그 책에서는 불교가 전파된 지역에 불교그림이 공통적으로 있고, 또한 그것을 활용한 공연이 있음을 설명하였다. 그리고 불교와는 관련 없지만 이러한 공연 형식은 세계적일 수 있음을 밝혔다. 그러나 문제는 '한국'은 다루어지지 않았다. 그것은 곧 그에 해당하는 공연의 기록과 전승이 없었기 때문이다. 이런 상황에서 2018년 삼척 안정사의 땅설법이 알려졌다. 학계는 한편으로 매우 반가워하면서도, 또 한편으로 고민을 하게 된다. 그 고민은 곧 '공시적, 통시적 보편성'으로 요약된다. 과연 삼척 안정사에서 전승하고 있는 땅설법이 그 절만의 특이 유형인가? 아니면 전승이 안되었을 뿐 전국적인 단위에서 보편적인가 하는 문제이다. 그러나 이런 본질적 질문에 앞서 우린 아직 충분히 안정사 땅설법의 전모를 알지 못하고 있다. 그래서 본고는 안정사 땅설법의 전체적인 윤곽을 보이기 위해 마련되었다. 땅설법 전체에 공통적으로 '그림'(변상도)이 쓰이며, 그것을 어떠한 방식으로 운용하는지 다양한 방식을 이해하는 것이 땅설법을 이해하는 첫걸음이다. 땅설법은 본전으로 5개의 레퍼토리, <석가모니일대기(釋迦牟尼一代記)>, <선재동자구법기(善財童子求法記>,<목련존자일대기(目連尊者一代記)>, <성주신일대기(成造神一代記)>, <신중신일대기(身衆神一代記)>를 가지고 있다. 또 별전으로 <만석중득도기(曼碩衆得道記)>, <안락국태자경(安樂國太子經)>, <태자수대나경(太子須大拏經)>, <심청효행록(沈淸孝行錄)>, <삼한세존일대기(三韓世尊一代記)>,<위제희부인만원연기(韋提希夫人滿願緣起)> 등이 있다. 공통적으로 불교적 인물의 일대기 서사구조를 취한다. 이 서사를 진행하는데 있어 가장 중심이 되는 것이 변상도이며, 이 변상도의 내용을 다양한 방식으로 알려주는 것이 땅설법이다. 서사의 실마리가 되는 변상도의 경우 빛이 없는 저녁에는 볼 수 없는 문제가 생겨 특별한 고안이 필요했다. 그렇게 만들어진 것이 그림자극과 영등(影燈)의 방식이다. 즉, 땅설법은 세 가지 방식의 공연 방식이 있다. 첫 번째가 변상도를 이용하는 방식이고, 두 번째가 그림자를 이용하는 방식이다. 세 번째가 영등의 방식이다. 이러한 방식은 레퍼토리의 내용에 따른 선택이 아닌 공연 환경에 따른 선택이다. 빛이 있어 그림을 볼 수 있으면 변상도를 이용한다. 그러나 저녁이 되면 어두워 볼 수 없으므로(과거 전기가 들어오지 않았던 시절) 그림자나 영등의 방식을 취했다. 이렇게 땅설법에서 시각적인 방식을 도구로 활용한 것은 단순히 구비문화 차원에서 한단계 진일보한 시각문화로의 이행을 확인할 수 있는 것이다. 더욱이 구비서사와는 달리 함축되어 있는 이미지의 힘은 감성적 자극을 통해, 보는 이로 하여금 불교의 신비함을 체감할 수 있는 기회를 제공했다..

• 한국운동역학회지
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• 제13권3호
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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.

• 전기전자학회논문지
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• 제25권2호
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• pp.362-370
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• 2021

본 논문에서는 휠체어 사용자의 이동권 확보를 위한 계단 승강 로봇 개발에 있어 ToF센서 및 IMU의 데이터를 기반으로 자율 계단 승강 기법을 제시하였다. 자율 계단 계단 승강 기법은 랜딩기어 동작 시점을 위치로 구분하고 상태 머신을 활용하여 제어하였다. 본 연구에서 제시한 이론의 검증을 위해 표준 기준의 모형 계단을 제작하여 실험하였다. 진입각 확보 실험을 통해 랜딩기어의 동작 길이 평균 오차는 2.19%, Pitching 기준 진입각 평균 오차는 2.78%로 부드러운 진입을 확인하였고, 자율 계단 승강 기법의 단계 구분 및 상태 전이를 검증하였다. 제안된 기법의 실적용 시 교통약자들의 이동제약을 줄일 수 있을 것이고, 이동권 보장을 통한 자립심의 고취가 기대된다.