미끄럼 발생에 따른 보행 패턴의 변화

김선필 경주대학교 2001 論文集 Vol.14 No.-

This study investigates the balance adjustment of walking to prevent a slipping accident. Gait analyses for six subjects were performed o three different road conditions; normal, virtual slip information, slippery surface with oil contaminant. 1. On the slippery ground surface, the gait pattern was modified into the longer supporting time to secure balance recovery. Also, the foot strike angle showed significant variation. 2. Prior to foot strike on the surface, the subjects appeared a tendency to raise their body center, and at heel strike, the vertical projection ratio of the body center on the surface increased. The maximum vertical velocity of the body center was adjusted to before take-off on the slippery surface from right after the toe’s take-off of the swing leg in normal gait. 3. During the later supporting period after slip. the ankle decreased the positive moment and also, did not show proper joint extension and energy. Thus, the ankle generated less energy compared to normal gait. At the knee, the subjects showed an abnormal flexion after extending, and at the hip. They did not execute normal flexion moment prior to heel strike and showed great energy absorption during supporting period.

역동역학 최적화 기법에의한 근골격 제어 연구

김선필 경주대학교 1999 論文集 Vol.12 No.2

Knowledge of the forces transmitted by muscles, ligaments, and the articular surfaces at the joint is fundamental for understanding the mechanics of human movements, and for improving the diagnosis and treatment of joint injuries. Unfortunately, muscle, ligament, and the articular contact forces cannot be measured non-invasively. Also, because the number of muscles forms a structually undeterminate system, straightforward methods employing force and moment equilibrium cannot be used to determine the forces in these structures. The application of the optimal control theory to dynamic musculoskeletal models was potentially the most powerful method for determining musculoskeletal forces during movement. Though the optimal control theory has previously been applied to study human jumping, accurate simulation of human motion and convergence to an optimal control solution incurs great computational expense. In this research, we investigate a new method for estimating musculoskeletal forces and activations from a given movement trajectory. The method combines conventional inverse dynamics with optimization utilizing a dynamic musculotendon model. The method uses only very limited computational power, which makes it a useful tool especially, for complex systems like the maximum height jumping model.

달리기 속도변화에 따른 관절일률의 비교분석

김선필 경주대학교 정보전자기술연구소 2005 情報電子技術論叢 Vol.4 No.-

In this study, running motion was measured at 5 given velocity. The subjects were high school students who participated with bare feet. To achieve this study, four video cameras, force platform and running timer were used. In addition, dynamic variables were calculated in Gait Lab for Window 2.0 using kinematic variables that were educed by segment measuring coefficient and Kwon3D motion analysis program. 1. The positive work and net work were calculated from the power-time plot of individual joint. These works increase according to running speeds. 2. Total works were calculated from the positive work and net work of individual joint. These works also increase according to running speeds. 3. The supposed works in this study can be used as the index of mechanical energy consumed by running.

미끄럼 발생시 노인의 보행 동작변화 연구

김선필,원문학 경주대학교 2002 論文集 Vol.15 No.-

This study investigates the balance adjustment of walking to prevent a slipping accident in the elderly Gait analyses for six elderly subjects were performed on three different road conditions, normal surface, virtual slip information on the normal surface, slippery surface with oil contaminant. 1. On the slippery ground surface, the g a t pattern was modified into the longer supporting time to secure balance recovery. However, the foot strike angle showed insignificant variation from slippery motion. 2. On three different road conditions, the subjects appeared a tendency to raise their body center, and increased the vertical projection ratio of the body center on the surface. The maximum vertical velocity of the body center was adjusted to before take-off on the slippery surface from night after the toe's take-off of the swing leg in normal gait. 3. Dung the latter supporting period after slip, the subject decreased the positive moment and positive energy during ankle extension. The subject showed an abnormal extension at the knee during the supporting period. At the hip, the subjects showed the noticeable pattern of flexion moment during the supporting period.

멀티링크 토션빔 형식의 후륜 현가장치에 대한 내구수명 평가

김선필 경주대학교 2003 論文集 Vol.16 No.-

This study investigated the durability analysis of a multi-link torsion beam rear suspension for a front drive vehicle. To validate the life prediction, the finite element model of the suspension was compared with the photoelastic and strain gauge measurements in each direction of static loads: longitudinal, lateral, and vertical. Also, the fatigue life was evaluated through bench tests and real road tests. The load conditions for bench tests and model's prediction were collected from a test car of durability proving ground. The shock absorber bracket was found to be the weakest area with life prediction of 46,000 km. In addition, the sensitivity analysis for the spring coefficient of the shock absorber assembly was examined to improve the model's prediction.

3자유도 구형관절 운동기기의 위치 해석

김선필 경주대학교 정보전자기술연구소 2008 情報電子技術論叢 Vol.7 No.-

This paper investigates the position analysis of a spherical three degree of freedom parallel joint module, which is used in the exercise equipment for balance and leg-strength improvement of aged people. The joint module has three link chains which consists of two links and three revolute joints, and its all joints intersect at the global point located at the module's center. The paper shows the explicit mathematical procedure for deriving the closed form solutions in the inverse and forward position analysis of this parallel joint module.

유전자알고리즘을 이용한 인체 근골격 시스템의 최적화제어 모델 개발

김선필 慶州大學校 2005 論文集 Vol.18 No.2

The study investigated genetic algorithms for the optimal control model of maximum height vertical jumping. The model includes forward dynamic simulations by the neural excitation-control variables. Convergence of genetic algorithms is very slow. In this paper the micro genetic algorithm(micro-GA) was used to reduce the computation time. Then a near optimal solution from micro-GA was an inital solution for VF02, which is one of well-developed and proven nonlinear programming algorithms. These approach provided the successful optimal solution without a resonable initial guess.

무릎 신전 메카니즘에서의 모멘트암

김선필 경주대학교 정보전자기술연구소 2004 情報電子技術論叢 Vol.3 No.-

The paper shows that the moment arm of the knee extensor mechanism is equal to the perpendicular distance between the instantaneous screw axis and the line of action of the patellar ligament force, multiplied by the sine of the angle between those two lines. The tibia undergoes movements other than flexion-extension, most noticeably internal-external rotation about its long axis. Extension movements reflect a change in the direction of the screw axis of the knee. The angle between the screw axis and the patellar ligament force is not always 90 and also the perpendicular distance is a function of the location within knee. the location of the screw axis is in turn determined by the interaction between the geometry of articulating surface and the force vector of the muscles. Thus the moment arm exhibits a characteristic bell shape which peaks somewhere in the region 40-60 of flexion, and then decreases rather rapidly on either side of this peak.

노인의 낙상예방을 위한 구형 3자유도 운동기기 개발

김선필 경주대학교 정보전자기술연구소 2007 情報電子技術論叢 Vol.6 No.-

This study is a preliminary report to develop the exercise equipment for fall prevention in the elderly. Many previous researches proposed that proper elastic resistance training and/or balance training increase the positive effects of fall prevention and gait pattern. The study proposed a spherical three degree of freedom parallel mechanism as the exercise equipment for improving both balance performance and muscle strength of the elderly. The mechanism has three dyad chains which consists of two links and three revolute joints, and its all joints intersect at the global point located at the mechanism's center. Thus the mechanism produces the spherical motion of three rotations-roll, pitch, yaw.

부착슬립에 의한 강체변형을 고려한 철근콘크리트 보의 비선형해석

김선필,곽효경,Kim, Sun-Pil,Kwak, Hyo-Gyoung 한국전산구조공학회 2005 한국전산구조공학회논문집 Vol.18 No.1

An analytical procedure to analyze reinforced concrete (RC) beams subject to monotonic loadings is proposed on the basis of the moment-curvature relations of RC sections. Unlike previous analytical models which result the overestimation of stiffnesses and underestimation of structural deformations induced from ignoring the shear deformation and assuming perfect-bond condition between steel and concrete, the proposed relation considers the rigid-body-motion due to anchorage slip at the fixed end. The advantages of the proposed relation, compared with the previous numerical models, are on the promotion in effectiveness of analysis and reflection of influencing factors which must be considered in nonlinear analysis of RC beam by taking into account the nonlinear effects into the simplifying moment-curvature relation. Finally, correlation studies between analytical and experimental results are conducted to establish the applicability of the proposed model to the nonlinear analysis of RC structures. 이 논문에서는 단면성질을 나타내는 모멘트-곡률 관계에 토대를 둔 해석모델을 제안하였다. 기존의 제안된 해석방법에서는 모멘트-곡률 관계가 완전부착을 가정한 휨거동만을 주요한 거동으로 가정하여 구조물의 응답을 과소평가하고 강성을 과대평가한 것과는 달리 제안된 해석 방법에서는 접합부의 부착슬립에 의한 강체변형을 산정할 수 있는 알고리즘을 개발하였고 나아가 등가휨강성을 이용하여 부착슬립에 의한 강체변형을 고려한 철근콘크리트 구조물의 해석을 수행하였다. 또한 모멘트-곡률 관계를 철근의 항복점을 기준으로 두개의 직선으로 간편화 시킴으로써 해석의 효율성을 높이는 한편 고려해야 할 비선형 거동특성을 효과적으로 반영하였다. 마지막으로 철근콘크리트 구조물의 비선형 해석에 대한 제안된 모델식의 적용성을 검증하기 위하여 해석결과와 실험값들의 비교를 수행하였다.