• Journal of Mechanical Science and Technology
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• 제18권2호
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• pp.211-220
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• 2004

It is well known that the geometry of the articular surface has a major role in determining the position of articular contact and the lines of action for the contact forces. The contact force calculation of the knee joint under the effect of sliding and rolling is one of the most challenging issues in this field. We present a 3-D human knee joint model including sliding and rolling motions and major ligaments to calculate the lateral and medial condyle contact forces from the recovered total internal reaction force using inverse dynamic contact modeling and the Least-Square method. As results, it is believed that the patella, muscles and tendon affect a lot for the internal reaction forces at the initial heel contact stage. With increasing flexion angles during gait, the decreasing contact area is progressively shifted to the posterior direction on the tibia plateau. In addition, the medial side contact force is larger than the lateral side contact force in the knee joint during normal human walking. The total internal forces of the knee joint are reasonable compared to previous studies.

• 대한기계학회논문집B
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• 제37권12호
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• pp.1121-1127
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• 2013

본 논문은 인체 견관절의 재활훈련을 위하여 견관절 근육에서 근전도를 측정하고 기능적 전기자극을 인가하는 실험적 연구를 다룬다. 견관절 근골격계의 구성 및 운동형상과 주요 기능을 토대로, 시상면 운동에서 주요 역할을 하는 견관절 근육을 실험대상으로 선정하였다. 첫 번째 실험으로 관절 각도에 따른 주요 근육의 표면근전도를 측정하였다. 관절 각도 변화와 표면면근전도 변화가 선형 비례하는 경향이 나타났다. 두 번째 실험으로 견관절 근육에 기능적 전기자극을 인가하면서 관절 각도를 측정하였다. 전기자극의 일정 범위에서 자극 전류 증가에 따라 관절 각도가 증가하는 경향이 나타났다. 능동형 재활훈련의 방안으로, 근전도 측정에 의해 근육의 운동의지를 감지하고 기능적 전기자극으로 근육의 장력 발생을 보조하는 게 가능함을 확인하였다.

• The Journal of Korean Physical Therapy
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• 제16권4호
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• pp.283-296
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• 2004

Joint mobilization and mechanical traction are common treatment forms for mechanical cervical spine problem. The purpose of the study was to investigate the effectiveness of cervical mobilization and mechanical traction on active range of motion of cervical spine. Sixty volunteers, aged between 21 and 24 years (mean age 22), were recruited. Each subject was divided into one of three groups; mechanical traction, general coordinative manipulation, and mobilization group. Active range of motions in the cervical were measured before and after each treatment technique from each subject on the three occasions. In the cervical range of motion, all subjects regardless treatment technique showed significantly increasing ranges after applied treatment technique in all directions except extension and left rotation in the mobilization group.

• 한국전문물리치료학회지
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• 제22권2호
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• pp.1-10
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• 2015

The common features of walking in patients with stroke include decreased gait velocity and increased asymmetrical gait pattern. The purpose of this study was to identify important factors related to impairments in gait velocity and asymmetry in chronic stroke patients. The subjects were 30 independently ambulating subjects with chronic stroke. The subjects' impairments were examined, including the isokinetic peak torque of knee extensors, knee flexors, ankle plantarflexors, and ankle dorsiflexors. Passive and active ranges of motion (ROM) of the ankle joint, ankle plantarflexor spasticity, joint position senses of the knee and ankle joint, and balance were examined together. In addition, gait velocity and temporal and spatial asymmetry were evaluated with subjects walking at their comfortable speed. Pearson correlations and multiple regressions were used to measure the relationships between impairments and gait speed and impairments and asymmetry. Regression analyses revealed that ankle passive ROM and peak torque of knee flexors were important factors for gait velocity ($R^2=.41$), while ankle passive ROM was the most important determinant for temporal asymmetry ($R^2=.35$). In addition, knee extensor peak torque was the most significant factor for gait spatial asymmetry ($R^2=.17$). Limitation in ankle passive ROM and weakness of the knee flexor were major contributors to slow gait velocity. Moreover, limited passive ROM in the ankle influenced the level of temporal gait asymmetry in chronic stroke patients. Our findings suggest that stroke rehabilitation programs aiming to improve gait velocity and temporal asymmetry should include stretching exercise for the ankle joint.

• 한국의류산업학회지
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• 제14권1호
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• pp.109-121
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• 2012

This study aims at developing ergonomics patterns for the sleeve of structural firefighting protective clothing through 3D motion analysis in order to ensure efficiency and safety of firefighters who are exposed to harmful environment at work. A new research pattern was developed by applying the total results of 3D motion analysis, changes of body surface length measurements, and 2D data on 3D body shape analysis on the size 3 patterns of the existing coat sleeve. For the sleeves, we used the body surface length of the range of shoulder's flexion and the joint angle of the range of wrist's ulnar deviation. And for the production of structural firefighting protective clothing using the research pattern, we recruited a recognized producer of structural firefighting protective clothing designated by KFI. Unlike everyday clothes, structural firefighting protective clothing should be able to fully protect the wearers from the harmful environment that threatens their lives and should not cause any restrictions on their movement. Therefore, the focus of research and development of such protective clothing should be placed on consistent development of new technologies and production methods that will provide protection and comfort for the wearer rather than production cost reduction or operational efficiency. This study is meaningful as it applied 3D motion analysis instead of the existing methods to develop the patterns. In particular, since 3D motion analysis enables the measurement of the range of motion, there should be continuous research on the development of ergonomics patterns that consider workers' range of motion.

• KCI Concrete Journal
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• 제13권1호
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• pp.27-34
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• 2001

This paper presents the results of a study on the effects of pounding at expansion joints of concrete bridges under earthquake ground motions. An engineering approach, rather than continuum mechanics, is emphasized. First, the sensitivity analysis of the gap element stiffness is performed. Second, usefulness of the analysis method for simulation of pounding phenomena is demonstrated. Third, the effects of pounding on the ductility demands measured in terms of the rotation of column ends are investigated. Two-dimensional FE analysis using a bilinear hysterestic model for bridge substructure joints and a nonlinear gap element for the expansion joint is performed on a realistic bridge with an expansion joint. Effects of the primary factors on the ductility demand such as gap sizes and characteristics of earthquake ground motion are investigated through a parametric study. The major conclusions are that pounding effect is generally negligible on the ductility demand for wide practical ranges of gap size and peak ground acceleration, but is potentially significant at the locations of impact.

• 대한정형도수물리치료학회지
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• 제13권1호
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• pp.36-43
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• 2007

Purpose: An objective analysis and observations were to be done on hemiplegia patients that are wearing a walking support device, Stroke shoes. Their improvements in walking pace, the reduction of distance between the two knee joint, the increase of curve angle of the knee joint and their steps and the reduction of ankle joint upon swing phase were analyzed using a 20 walking analyzer. Methods: An examination was carried out to see the patients' communication skill and independent walking and then let them walk with the Stroke shoes on to get results before and after wearing it. Simi Reality Motion Systems GmbH (Germany, 2007) was used to analyze the results regarding knee joint and ankle joint angle changes of sagitta plane and coronal plane, stepping distances, distances between the knees and walking pace. Results: 1. The articulation angle of ankle joint during swing phase decreased and knee joint has shown a statistically significant increase in such value(p<0.05). 2. Only knee joint showed a significant increase in articulation angle during heel strike(p<0.05). 3. Knee joint showed a significant increase in articulation angle during toe off(p<0.05). 4. The distance between the two knees as well as their foot steps significantly decreased compared with when Stroke shoes were not worn(p<0.05). 5. Stroke shoes with FES have shown positive effects on the patients in improving their walking styles overall. (p<0.05). Conclusion: There was an improvement in rotation walking pattern by a reduction in the distance between the knees after wearing Stroke shoes with FES. Plantar flexion reduced that occurred in ankle joint during walking and flexion angle increased in knee joint, both of which improved foot drop which was a major problem in hemiplegia patients. Also it is believed that the device will have some positive influences on knee joint stiffening paralysis to aid in improving inefficient walking phases.

• Structural Engineering and Mechanics
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• 제44권5호
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• pp.663-680
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• 2012

Previous major earthquakes revealed that most damage of the buried segmented pipelines occurs at the joints of the pipelines. It has been proven that the differential motions between the pipe segments are one of the primary reasons that results in the damage (Zerva et al. 1986, O'Roueke and Liu 1999). This paper studies the combined influences of ground motion spatial variations and local soil conditions on the seismic responses of buried segmented pipelines. The heterogeneous soil deposits surrounding the pipelines are assumed resting on an elastic half-space (base rock). The spatially varying base rock motions are modelled by the filtered Tajimi-Kanai power spectral density function and an empirical coherency loss function. Local site amplification effect is derived based on the one-dimensional wave propagation theory by assuming the base rock motions consist of out-of-plane SH wave or combined in-plane P and SV waves propagating into the site with an assumed incident angle. The differential axial and lateral displacements between the pipeline segments are stochastically formulated in the frequency domain. The influences of ground motion spatial variations, local soil conditions, wave incident angle and stiffness of the joint are investigated in detail. Numerical results show that ground motion spatial variations and local soil conditions can significantly influence the differential displacements between the pipeline segments.

• 스마트미디어저널
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• 제13권4호
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• pp.16-22
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• 2024

투구는 야구의 시작이라 할 만큼 야구에서 주요한 부분을 차지한다. 투구 동작의 정확한 분석은 경기력 향상과 부상 예방 측면에서 매우 중요하다. 올바른 투구 동작을 분석할 때, 현재 주로 사용되는 모션캡처는 환경적으로 치명적인 단점들이 몇 가지 존재한다. 본 논문에서 우리는 이러한 단점들이 존재하는 모션캡처를 대체하기 위하여 RGB 기반의 Human Pose Estimation(HPE) 모델을 활용한 투구 동작의 분석을 제안하며 이에 대한 신뢰도를 검증하기 위해 모션캡처 데이터와 HPE 데이터의 관절 좌표를 Dynamic Time Warping(DTW) 알고리즘의 비교를 통해 두 데이터의 유사도를 검증하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.200-205
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• 1989

The performance of conventional robot arms is inhibited by trade-off between speed and accuracy. Because these systems measure only joint angles, in spite of slow speed, they must rely on a stiff structure in order to attain positioning accuracy. Lightweight links would allow faster motion, but their flexibility would also produce positioning errors. This research is involved with the development and evaluation of an End-point Control System whose major goal is to compensate for link deflections and thus mitigate the speed versus accuracy conflict in conventional manipulator.