• 한국전문물리치료학회지
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• 제11권4호
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• pp.1-6
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• 2004

The kinematics involved in different landing strategies may be related to the occurrence of trauma. Several sources suggest that the angle of knee extension on touchdown and impact with the ground determines the magnitude of the impact force and, indirectly, knee loading. This study compared the initial knee angle and maximum knee flexion angle at the instant of impact on drop-landings between healthy men and women. In this study, 60 participants (30 males, 30 females) dropped from a height of 43 cm. A digital camera and video motion analysis software were used to analyze the kinematic data. When landing, there was significant difference between the two groups ($15.67{\pm}6.05^{\circ}$ in male, $24.10{\pm}6.34^{\circ}$ in female) in the mean knee flexion angle. The range of knee flexion on landing ($44.06{\pm}10.97^{\circ}$ in male, $36.96{\pm}9.99^{\circ}$ in female) also differed significantly (p<.05). The greater knee flexion that was observed in the male subjects would be expected to decrease their risk of injury. Women land with smaller range of knee flexion than men and this might increase the likelihood of a knee injury.

• 한국운동역학회지
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• 제20권1호
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• pp.67-73
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• 2010

The purpose of this study was to compare the differences in kinematic and kinetic parameters of the ankle and knee joint according to three landing direction(central, left, right). Fifteen collegiate male athletes(age: $22.7{\pm}3.5$ years, height: $174.9{\pm}7.1\;cm$, weight: $69.4{\pm}6.7\;kg$) with the right leg as dominant were chosen. The subjects performed series of drop landings in three directions. In terms of the three different landing directions, plantar flexion was the greatest during the central drop landings. For each initial contact of the landing direction, plantar flexion of the ankle was greatest at the central drop landing, inversion of the ankle was greatest at the right landing and valgus of the knee was greatest at the left drop landing. Regarding the peak force, the greatest was at the 1st peak force during the central drop landing. For the time-span of the 2nd peak force and the 2-1 peak force, both right sides resulted as the greatest. Therefore, with the appropriate training in landing techniques and developing neuromuscular training for proprioception by taking the injury mechanisms on ankle and knee during drop landings into account, it will assist in preventing such injuries.

• 대한의용생체공학회:의공학회지
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• 제29권3호
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• pp.222-230
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• 2008

This paper introduces a method of estimating the knee joint moment developed during MVC. By combining the Hill-type muscle model and analytic results on moment arm and musculotendon length change as a function of hip and knee joint angle, the knee joint moment at a specific knee joint angle during MVC is determined. Many differences between the estimated results and the experimental data are noted. It is believed that these differences originate from inaccurate information on the muscle-tendon parameters. The establishment of exact values for the subject's muscle parameters is almost impossible task. However, sensitivity analysis shows that the tendon slack length is the most critical parameter when applying the Hill-type muscle model. The effect of a change of this parameter on the muscle length force relationship is analyzed in detail.

• 대한인간공학회지
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• 제24권4호
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• pp.63-71
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• 2005

A laboratory study was performed to evaluate the effects of an aid(i.e. stick) on joint loadings. Six healthy young participants were recruited from Virginia Tech student population. Each participant has performed three normal walking and three stick walking trials. Normalized and integrated, ground reaction forces(GRFs) and joint moments were measured at ankle, knee, and hip joints from kinematic and kinetic data. The result suggests that stick walking significantly reduces vertical ground reaction force and joint moments at ankle and knee compared to normal walking.

• 한국운동역학회지
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• 제21권1호
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• pp.1-7
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• 2011

The purpose of this study was to investigate changes in kinetic and kinematic variables associated with an increase in upper body weight. Eighteen healthy male university students($175.96{\pm}4.19\;cm$, $70.79{\pm}8.26\;kg$) participated. Eight motion analysis cameras(Qualysis Oqus 500) and 2 force AMTI platforms(Advanced Mechanical Technologies Inc. OR6-7, US) were used to record motion and forces during the drop landing at a frequency of 120 Hz and 1200 Hz, respectively. QTM software(Qualisys Track Manager) was used to record the data, and the variables were analyzed with Visual 3D and Matlab 2009. For the drop landing, a box of $4{\times}2{\times}0.46\;m$ was constructed from wood. Knee and ankle maximum flexion angle, knee flexion angle, knee and ankle angle at landing, time for maximum ankle flexion after landing, and time for maximum knee flexion after landing were calculated. There was a significant change in the time for maximum and minimum ground force reaction and the time for maximum dorsal flexion after landing(p<.05) with increasing weight. There was no significant change for the hip, knee, and ankle ROM, whereas there was an increase in the angle ROM as the weight increased, in the order of ankle, knee, and hip ROM. This result shows that the ankle joint ROM increased with increasing weight for shock attenuation during the drop landing. There was a trend for greater ankle ROM than knee ROM, but there was no clear change in the ROM of the hip joint with increasing weight. In conclusion, this study shows the importance of ankle joint flexibility and strength for safe drop landing.

• 한국운동역학회지
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• 제16권4호
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• pp.83-94
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• 2006

The purpose of this study is to elucidate how walking speed influences on change of angles of lower extremity and ground reaction force in normal and obese people. One group with normal body weight who were experimented at a standard speed of 1.5m/s and the other obese group were experimented at two different walking speeds (standard speed of 1.5m/s and self-selected speed of 1.3m/s). We calculated angles of lower extremity and ground reaction force during stance phase through video recording and platform force measuring. When the obese group walked at the standard speed, dorsi-flexion angle of ankle got bigger and plantar-flexion angle of ankle got smaller, which were not statistically significant. There was no significant difference of knee joint angles between normal and obese group at the same speed walking but significant post hoc only for the first flexion of knee joint in obese group. $F_z1$ was bigger than $F_z3$ in vertical axis for ground reaction force in both groups at the standard speed walking and the same force value at self-selected speed in obese group. $F_y3$ was always bigger than $F_y1$ in anterior-posterior axis in both groups.

• 한국운동역학회지
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• 제28권3호
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• pp.159-164
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• 2018

Objective: The aims of this study were to determine the impact peak force and kinematic variables in running speed and investigate the relationship between them. Method: Thirty-nine male heel strike runners ($mean\;age=21.7{\pm}1.6y$, $mean\;mass=72.5{\pm}8.7kg$, $mean\;height=176.6{\pm}6.1cm$) were recruited in this investigation. The impact peak forces during treadmill running were assessed, and the kinematic variables were computed using three-dimensional data collected using eight infrared cameras (Oqus 300, Qualisys, Sweden). One-way analysis of variance ANOVAwas used to investigate the influence of the running speed on the parameters, and Pearson's partial correlation was used to investigate the relationship between the impact peak force and kinematic variables. Results: The running speed affected the impact peak force, stride length, stride frequency, and kinematic variables during the stride phase and the foot angle at heel contact; however, it did not affect the ankle and knee joint angles in the sagittal plane at heel contact. No significant correlation was noted between the impact peak force and kinematic variables in constantrunning speed. Conclusion: Increasing ankle and knee joint angles at heel contact may not be related to the mechanism behind reducing the impact peak force during treadmill running at constant speed.

• 대한의용생체공학회:의공학회지
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• 제18권1호
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• pp.71-78
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• 1997

Kinematic and kinetic studies were performed to investigate the walking characteristics on a treadmill with various slopes at the same speed of 1.25m/sec. Six different slopes of the treadmill were selected . -4%(-$2.3^{\circ}$), 0%($0^{\circ}$), 5%($2.9^{\circ}$), 10%($5.7^{\circ}$), 15%($8.6^{\circ}$), and 20%($11.3^{\circ}$). With increased slopes of the treadmill, both hip and knee flexion angles significantly increased at initial contact, and the maximum hip flexion during swing phase and the maximum knee flexion during stance phase also significantly increased Ankle dorsiflexion angle at initial contact and the maximum dorsiflexion increased with increased slopes. However, the maximum plantarflexion in early swing was slightly reduced with increased slopes. Hip extension in late stance and the maximum knee flexion in early swing was not changed sigilificantly with increased slopes. As for the vertical ground reaction force, compared to the yond level walking, both the first and the second peak forces increased, but the mid-support force decreased.

• 대한의용생체공학회:의공학회지
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• 제24권4호
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• pp.363-367
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• 2003

인공무릎관절의 수명에 직접적인 영향을 주는 인자는 접촉면에 대한 접촉면적과 압력분포이다 따라서. 이에 대한 실험적인 평가가 필요하였고 knee simulator 혹은 K-scan sensor를 포함한 시스템과 같은 많은 연구가 진행되어 왔다. 그러나 지금까지 보행주기에 따른 연속적인 인공관절 운동에 대한 접촉면의 압력분포를 실시간으로 분석한 연구는 미흡하다 따라서 본 연구의 목적은 보행주기를 모사하는 simulator와 I-scan을 이용하여 연속적인 동작에 따른 접촉면의 압력분포를 분석함에 있다. 본 연구의 목적을 이루기 위해서 생체내 인공관절 환경을 정확히 표현할 수 있는 knee simulator를 제작하였다. 네 방향의 자유도를 갖고 있는 본 simulator는 soft tissue의 기능을 포함하고 있고 PC Program을 통하여 압축하중과 femoral component의 굴곡각을 조절할 수 있다. 본 시스템의 I-scan sensor는 보행주기에 따른 압력분포를 분석할 수 있다. 보행주기에 대한 압력분포는 압축하중곡선에 따라 주요하게 변화함을 알 수 있고 운동성에 영향을 쿠는 압력중심의 위치도 변한다는 것을 알 수 있다. 따라서 본 연구에서 제작한 knee simulator는 보행주기 같은 특정의 운동정보를 이용하여 접촉면의 압력분포 및 운동성 같은 기계적 성능을 평가할 수 있고 형상 설계를 위한 기초 자료를 제공할 수 있다.

• 한국구조물진단유지관리공학회 논문집
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• 제24권1호
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• pp.35-42
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• 2020

필로티 건물의 평면 비정형으로 인한 비틀림 거동은 비틀림 회전 최외단 기둥에 과도한 층간변위를 일으키고 이로 인하여 기둥의 전단파괴를 유도할 수 있다. 필로티 건물의 비틀림 거동을 제어할 수 있는 내진보강 공법으로서 벽체 증설, 철골 프레임 또는 철골 가새 추가공법 등이 사용될 수 있으나 이와 같은 공법 들은 필로티 층의 공간 개방성을 저해할 우려가 있다. 따라서 본 연구에서는 필로티 층의 공간 개방성을 유지할 수 있는 내진보강 공법으로서 knee brace를 활용하기 위하여 knee brace 보강재 단면 형상 및 보강재 설치 각도 등을 변수로 보강된 필로티 건물에 대하여 선형동적해석 및 비선형 정적해석(pushover analysis)을 수행하고 내진성능 평가 및 knee brace의 비틀림 제어효과를 분석하였다. 연구 결과 knee brace로 보강 시 기둥의 전단력은 증가하였으나 비틀림 변형을 제어하는데 효과가 있는 것으로 나타났다. knee brace와 기둥 사이를 30°로 보강 시 60°의 경우보다 기둥의 전단력은 적게 증가하였으며, 단면형상 □, ◯ 그리고 H 순으로 기둥의 횡변위가 적게 발생하였다.