http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
구승범(Seungbum Koo) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
The knee has a complex kinematics during activities. Understanding the natural kinematics is important for developing knee arthroplasties and designing rehabilitation program which are supposed to restore the natural function of the knee. Previous works showed that the knee has both medial and lateral pivoting motion during walking while the lateral pivoting is dominant. This study investigated the pivoting motion of the knee to understand the timing of medial and lateral pivoting during normal walking for 54 knees from 27 healthy subjects. The result showed that the knee has lateral pivoting in general for whole stance phase. The significant lateral pivoting (binomial probability > 70%) happened in 5 time periods and 68% of stance phase. It revealed the general pivoting type and timing in healthy population and can be used as a guideline for the normal function of the knees.
Young-Jun Koo(구영준),Mingi Jung(정민기),Seungbum Koo(구승범) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4
Neuromuscular disorders, such as cerebral palsy, stroke, and sarcopenia, induce weak ankle plantar flexors. The ankle plantar flexors play an essential role in push-off during walking, and there must be compensation strategies for its injuries. The purpose of this study was to simulate the pathology gait of weak ankle plantar flexors and to analyze compensation strategies for weak ankle plantar torque. The gait motion of a healthy subject was measured. A musculoskeletal model was built in the RaiSim. A gait controller was obtained through reinforcement learning by mimicking the measured motion. The maximum strengths of ankle plantar flexors were reduced to 75%, 50%, and 25% to make injured models. The intact and injured models were simulated using the same gait controller. When the ankle had maximum plantarflexion torque, hip flexion torques were 45.5 Nm, 55.3 Nm, 52.9 Nm, and 50.5 Nm for intact, 75%, 50%, and 25% models, respectively. Also, durations of push-off were 14%, 14%, 16%, and 20% of the gait cycle. Weak ankle plantar flexors were compensated by hip flexion torque and the prolonged push-off period when the weakness was severe.
구영준(Youngjun Koo),구승범(Seungbum Koo) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
Accurate measurement of joint kinematics play an important role in understanding joint disease and assessing musculoskeletal disorders. Motion capture system was widely used to quantify joint kinematics. However, joint kinematics acquired by motion capture system was affected by soft tissue artefacts such as skin movements. To quantify accurate joint kinematics, we include the skin movements to analyze. Previous studies have used intrusive methods such as bone-pins or external fixators to quantify skin movements. These devices could be affected by gait environments and change gait motion. In this study we used a Bi-Plane Fluoroscopic (BPF) system and a motion capture system to quantify skin movements without bone-pins or external fixators. Seven healthy young males participated in this study. Multiple reflective markers were attached on both thigh and shank during treadmill walking at 0.9 ㎧, 1.2 ㎧ and 1.5 ㎧. Skin movements were calculated from BPF system and motion capture system by Anterior-Posterior (AP), Superior-Inferior (SI) and Medial-Lateral (ML) direction. Skin movements of thigh were larger than shank. Skin movements were largest at top of thigh. Skin movements in AP direction were larger than other directions. This study successfully quantified the kinematics with skin movements.
이중빈(Jungbin Lee),구승범(Seungbum Koo) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
Gait is important motion that contains biological information. Individual gait pattern is determined by subject’s habit, body type and diseases. Motion capture system is used to measure joint motion but is limited to capture within a laboratory. Optical camera is portable, simple to configure and take photographs of movement of a person, while it produces only two-dimensional information. The purpose of the study was to estimate three-dimensional pose and joint angles from two-dimensional sequential images of walking motion. Three-dimensional trajectories of body markers from three subjects and five motions were pooled together and their mean pose and principal components were obtained. One of the motion capture data was projected to a camera plane by assuming a fixed camera position. Optimizations to calculate a weight matrix of the principal components of body pose were performed with and without a constraint of body segment length to match the plane projected marker positions. Mean three-dimensional errors (standard deviation) of estimated marker trajectory were calculated using measured marker trajectory. Three-dimensional errors with and without constraint of body segment length were 3.44(±0.65) cm and 3.25(±0.80) cm, respectively. Two-dimensional errors (standard deviation) of projected marker to image were calculated using original image. Two-dimensional errors were 1.63(±0.41) pixel and 1.40(±0.38) pixel respectively. Flexion and extension angle of knee was estimated as RMS error, 2.54degree and 2.28degree respectively.