• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.39-40
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• 2009

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.4 s.247
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• pp.435-441
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• 2006

The anterior cruciate ligament(ACL) is an important stabilizer of knee joint. The ACL injury of knee is common and a serious ACL injury leads to ligament reconstruction surgery. Gait analysis is essential to identify knee condition of patients who display abnormal gait. The purpose of this study is to evaluate and classify knee condition of ACL deficient patients using a nonlinear dynamic method. The nonlinear method focuses on understanding how variations in the gait pattern change over time. The experiments were carried out for 17 subjects(l2 healthy subjects and five subjects with unilateral deficiency) walking on a motorized treadmill for 100 seconds. Three dimensional kinematics of the lower extremity were collected by using four cameras and KWON 3D motion analysis system. The largest Lyapunov exponent calculated from knee joint flexion-extension time series was used to quantify knee stability. The results revealed the difference between healthy subjects and patients. The deficient knee was significantly unstable compared with the contralateral knee. This study suggests an evaluation scheme of the severity of injury and the level of recovery. The proposed Lyapunov exponent can be used in rehabilitation and diagnosis of recoverable patients.

• Journal of the Ergonomics Society of Korea
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• v.24 no.4
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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.

• Journal of the Korean Physical Therapy Association
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• s.3
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• pp.3-9
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• 1981

The effects of physical therapy on the knee joint dysfunction due to femur fracture C.E. Parkr, J. Baik, J.H. Rhee* One hundred and twenty - four knee joint dysfunction due to femur fractured treated, at dept of physical therapy Incheon christian hospital for 3 years since 1978were reviewed. Despite lack of progress note , the late results in sixty- eight cases of joint dysfunction were analysed clinically. The reselt obtained in this study are summerized as follow :1. Sex distribution of total patients surveyed showed that 73.5% in male, and26,5% in female. In age distribution, the most predominent age group was 21 ~.30years with 35.3%.2. About 56% of the cases were caused by traffic accident,3. The modalities of physical therapy suitable to each cases were applied, 94.1 %of all cases were treated with hot pack, 98.5 % active exercise, 73.5 % isometric exerclse .4. The improvement by physical therapy on knee joint dysfunction was classified into 4 grades and showed following results ; excellent 66.1%, good 26.5%, fair5.9% and poor 1,5% respectively.

• Korean Journal of Applied Biomechanics
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• v.26 no.4
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• pp.407-412
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• 2016

Objective: The aim of this study was to analyze the net joint moment and joint power of the lower extremity during squat in female patients with genu varum. Method: Eight female patients with genu varum were asked to do regular squats, and their net joint moment and joint power were compared to those of another eight female participants with straight legs. Their video recordings and ground reaction force data were analyzed to be used as a theoretical evidence of squatting effectively for female patients with genu varum. Results: Squats had a higher impact on internal knee joint rotation and ankle joint flexion moments in the genu varum group than in the straight leg group due to their weak and short hip joint muscles. Conclusion: There is a need to develop a squat movement that is appropriate for women with genu varum in order to distribute overload efficiently among the hip, knee, and ankle joints and to strengthen the muscles in a balanced way.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.315-316
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.63-64
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.1005-1006
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.961-962
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• 2011

• Journal of Mechanical Science and Technology
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• v.17 no.6
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• pp.825-835
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• 2003

Previous studies have demonstrated the importance of joint angle errors mainly due to skin artifact and measurement errors during gait analysis. Joint angle errors lead to unreliable kinematics and kinetic analyses in the investigation of human motion. The purpose of this paper is to present the Joint Averaging Coordinate System (JACS) method for human gait analysis. The JACS method is based on the concept of statistical data reduction of anatomically referenced marker data. Since markers are not attached to rigid bodies, different marker combinations lead to slightly different predictions of joint angles. These different combinations can be averaged in order to provide a "best" estimate of joint angle. Results of a gait analysis are presented using clinically meaningful terminology to provide better communication with clinical personal. In order to verify the developed JACS method, a simple three-dimensional knee joint contact model was developed, employing an absolute coordinate system without using any kinematics constraint in which thigh and shank segments can be derived independently. In the experimental data recovery, the separation and penetration distance of the knee joint is supposed to be zero during one gait cycle if there are no errors in the experimental data. Using the JACS method, the separation and penetration error was reduced compared to well-developed existing methods such as ACRS and Spoor & Veldpaus method. The separation and penetration distance ranged up to 15 mm and 12 mm using the Spoor & Veldpaus and ACRS method, respectively, compared to 9 mm using JACS method. Statistical methods like the JACS can be applied in conjunction with existing techniques that reduce systematic errors in marker location, leading to an improved assessment of human gait.