• Korean Journal of Applied Biomechanics
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• v.20 no.2
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• pp.191-196
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• 2010

The purpose of this study was to investigate the effect of gait speed and walkway slope on the body acceleration, for the future validation of using an accelerometer in the estimation of energy consumption. Ten young healthy subjects with accelerometers on the upper thigh and ankle walked on a treadmill at 9 conditions(three speeds ${\times}$ three slopes) for 5 minutes. Acceleration signals of four directions, i.e. anterior-posterior(AP), medio-lateral(ML), superior-inferior(SI) and vector sum(VS) directions, of each sensor were measured, and root means squared(RMS) values of them were used as analysis variables. As statistical analysis, repeated measure two-way ANOVA was performed for RMS accelerations at each attachment sites, with slope and velocity as independent factors. At both the upper thigh and ankle, RMS acceleration of all directions were affected by gait velocities(p<.001) showing greater accelerations for higher velocities. Contrary to expectations, no slope effect existed in RMS accelerations at hip. Moreover, RMS acceleraion at ankle decreased with slope in SI and VS directions(p<.01). These results suggests that RMS acceleration cannot reflect the change in physical activity due to the change in walkway slope.

• Journal of Biomedical Engineering Research
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• v.30 no.6
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• pp.516-520
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• 2009

The purpose of this study is to determine optimal filtering condition and threshold for the detection of gait-cycles for various walkway slopes as well as gait velocities. Ten young healthy subjects with accelerometer system on thigh and ankle walked on a treadmill at 9 conditions (three speeds and three slopes) for 5 minutes. Two direction signals, i.e. anterior-posterior (AP) and superior-inferior (SI) directions, of each sensor (four sensor orientations) were used to detect specific events of gait cycle. Variation of the threshold (from -1G to 1G) and lowpass cutoff frequency (fc) were applied to the event detection and their performance was evaluated according to the error index (EI), which was defined as the combination of the accuracy and false positive rate. Optimal fc and threshold were determined for each slope in terms of the EI. The optimal fc, threshold and their corresponding EI depended much on the walkway slope so that their coefficients of variation (CV) ranged 19~120%. When all data for 3 slopes were used in the identification of optimal conditions for each sensor, the best error indices for all sensor orientations were comparable ranging 1.43~1.76%, but the optimal fc and threshold depended much on the sensor position. The result indicates that the gait-cycle detection robust to walkway slope is possible by threshold method with well-defined filtering condition and threshold.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.635-636
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• 2009

• Korean Journal of Applied Biomechanics
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• v.26 no.2
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• pp.161-166
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• 2016

Objective: The purpose of this study was to determine the knee and ankle joint kinematics and kinetics by comparing downhill walking with valley-shape combined slope walking. Method: Eighteen healthy men participated in this study. A three-dimensional motion capture system equipped with eight infrared cameras and a synchronized force plate, which was embedded in the sloped walkway, was used. Obtained kinematic and kinetic parameters were compared using paired two-tailed Student's t-tests at a significance level of 0.05. Results: The knee flexion angle after the mid-stance phase, the mean peak knee flexion angle in the early swing phase, and the ankle mean peak dorsiflexion angle were greater during downhill walking compared with valley-shape combined slope walking (p < 0.001). Both the mean peak vertical ground reaction force (GRF) in the early stance phase and late stance phase during downhill walking were smaller than those values during valley-shape combined slope walking. (p = 0.007 and p < 0.001, respectively). The mean peak anterior GRF, appearing right after toe-off during downhill walking, was also smaller than that of valley-shape combined slope walking (p = 0.002). The mean peak knee extension moment and ankle plantar flexion moment in late stance phase during downhill walking were significantly smaller than those of valley-shape combined slope walking (p = 0.002 and p = 0.015, respectively). Conclusion: These results suggest that gait strategy was modified during valley-shape combined slope walking when compared with continuous downhill walking in order to gain the propulsion for lifting the body up the incline for foot clearance.

• Physical Therapy Korea
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• v.8 no.1
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• pp.89-96
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• 2001

This study addresses the effects of treadmill training on hyperextended knee and cadence in patients with hemiplegia. A single subject research design with multiple baselines across individuals was used for the study. Two patients with hemiplegia participated in the experiment. The experiment consisted of interventions where the patients were asked to ambulate for 15 minutes at a comfortable walking speed on the treadmill with 11% slope grade and were allowed to rest for 10 minutes. Patients, then, were asked to ambulated 20 meters at walkway. The number of occurrences of knee hyperextension and the total number of steps were recorded. The results showed that the occurrence of knee hyperextension decreased by approximately 30% after the first session of the treadmill training and continued to gradually decrease during the following sets of treadmill training. Meanwhile, there was a slight increase in the cadence to a negligible extent. These results suggest that the gait training on the sloped treadmill may be helpful for correcting the knee hyperextension in patients with hemiplegia.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.32 no.4
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• pp.132-142
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• 2014

This study is the first stage to identify distinctive characteristics of American Romantic Garden compared to English Romantic Garden. The purpose of the study is to identify characteristics of transitional garden in the early period of America by analyzing of Paca garden, Mount Vernon and Monticello when English Naturalistic Garden was firstly imported. The analysis studied historical background, people who designed garden, formal garden and characteristics of natural garden through reference. Also based on data through reference and field research, spatial configuration and garden factors of each site were analyzed. In spatial configuration, straight line and curve line, formal terrace and natural slope, visible axis and invisible axis, symetric and asymmetric, and perspective and oblique perspectives were used as analyzing factors. As a result of analysis, each garden showed different type from that of formal gardens from colony period, which is natural garden of asymmetric garden(English natural garden) coexisted. Paca garden which planned formal garden and natural garden in each space showed characteristics of each space, but in formal garden residential axis and garden axis does not coincide which shows it is out of formal garden type. Such phenomena and the fact that naturalistic garden coexist in the same garden shows that the formal garden type from early days in US is starting to change in different types. Mount Vernon garden, similar to Paca garden, was designed to have two different types of gardens in harmony rather than divide the space into different space and design it. It adapted serpent walkway but shows symmetric by central axis and considered formalistic plan through same materials. However through terrace in hills and spatial plan of oblique perspective, one could observe that naturalistic type was beginning to settle in US gardens. Through Monticello analysis, space was designed with major characteristics of naturalistic garden which is serpent walkway, ornamental farm, winding flower bed grove and bush and oblique perspective, and it completely duplicates characteristics of naturalistic garden which could not be found in gardens imported from UK.