• Korean Journal of Applied Biomechanics
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• v.23 no.1
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• pp.53-62
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• 2013

The methods of fitting a circle to measured data, geometric fit and algebraic fit, have been studied profoundly in various areas of science. However, they have not been applied exactly to a biomechanics discipline for locating the center of rotation of a human joint. The purpose of this study was to generalize the methods to fitting spheres to the points in 3-dimension, and to estimate the center of rotation of a hip joint by three of geometric fit methods(Levenberg-Marquardt, Landau, and Sp$\ddot{a}$th) and four of algebraic fit methods(Delogne-K${\aa}$sa, Pratt, Taubin, and Hyper). 1000 times of simulation experiments for flexion/extension and ad/abduction at an artificial hip joint with four levels of range of motion(10, 15, 30, and $60^{\circ}$) and three levels of angular velocity(30, 60, and $90^{\circ}$/s) were executed to analyze the responses of the estimated center of rotation. The results showed that the Sp$\ddot{a}$th estimate was very sensitive to the marker near the center of rotation. The bias of Delogne-K${\aa}$sa estimate existed in an even larger range of motion. The Levenberg-Marquardt algorithm of geometric fit and the Pratt of algebraic fit showed the best results. The combination of two methods, using the Pratt's estimate as initial values of the Levenberg-Marquardt algorithm, could be a candidate of more valid estimator.

• PNF and Movement
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• v.5 no.2
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• pp.47-54
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• 2007

Purpose : The purpose of this study were to determine the effect of a Elastic Theraband Exercise Based of PNF L/E pattern on the gait of the chronic Hemiplegic Patients. Methods : We selected the 20 chronic Hemiplegic Patients not given treatment now and divided them into two groups of both 10 Elastic Theraband group and 10 Self Exercise. The first group went through a Elastic Theraband Exercise Based of PNF L/E pattern 30 minutes a day, 5 times a week, for 6 weeks. Exercise used to blue elastic band which 2 patterns of PNF by 1) hip extension - abduction - internal rotation with knee extension. 2) hip flexion - adduction - external rotation with knee flexion. The latter group experienced Self Exercise, 30 minutes a day, 5 times a week, for 6 weeks. Firstly, we measured the absolute improvement of gait velocity(m/s), cadence(steps/min) among walking characters. Secondly, we measured the functional walking ability such as Functional Ambulatory Category(FAC, score out of 5), Modified Motor Assesment Scale(MMAS, score out of 6). Data analysis was performed with using SPSS 12.0 win program. The descriptive analysis was used to obtain average and standard deviation. The independent t-test and the paired t-test were used to compare both the groups about pre and post training test. Treatment effects were established by pre and post assessment. Subjects tolerated the training well without side-effects. Therefore, the results of this study were as follows; Results : 1. There was a more significant improvement of Gait velocity(0.12m/s) Elastic Theraband group(p<.05). 2. There was a more significant improvement of cadence(9.40steps/min) Elastic Theraband group(p<.05). Conclusion : As we can see from above, the findings suggest that Elastic Theraband may be more effective than the Self Exercise for improving some gait parameters such as Gait velocity and Cadency. This conclusion also suggest that Elstic Theraband is more effective for the improvement of gait of chronic Hemiplegic Patients.