• PNF and Movement
• /
• v.7 no.4
• /
• pp.31-36
• /
• 2009

Many daily activities require people to complete a motor task while walking. Substantial gait decrements during simultaneous attention to a variety of cognitive tasks have been shown by a group of severely injured neurological patients of mixed etiology. And previous studies have shown that the attentional load of a walking-associated task increased with its level of difficulty. The purpose of this study was to analyze subjects' gait changes are affected by the effects of arithmetic task difficulty and performance level. Participants performed a walking task alone, three different Arithmetic tasks while seated, and among them, two kinds of the simillar Arithmetic tasks in combination with walking. Reaction time and accuracy were recorded for two of the Arithmetic tasks. The mean values of the gait were measured using a Timed Up and Go test among 11 with post-stroke patients while walking with and without forward counting (WFC) and backward counting(WBC).There was significant Arithmetic Task Difficulty level between the 10-forward counting task condition(FC) and the 10-backward counting task condition(BC)(p=0.008). The mean values of T.U.G time were significantly higher under backward counting dual-task condition than during a simple walking task(p=0.009) and WFC(p=0.009). The change in T.U.G time during WFC was higher when compared with the change during a simple walking, but there was no significant difference (p=0.246). This study suggesting that a high interference could be linked with a high level of difficulty, whereas adaptive task enabled participants to perfectly share their attention between two concurrent tasks. Future research should determine whether dual task training can reduce gait decrements in dual task situations in people after stroke. And the dual-task-based exercise program is feasible and beneficial for improving walking ability in subjects with stroke.

• Journal of Digital Convergence
• /
• v.14 no.6
• /
• pp.439-448
• /
• 2016

The population over 65 years old is 12.7% of total population in 2014 and Korea is going to be an aged society in the near future. The transportation vulnerable including the aged should be guaranteed in walking mobility under safe and comfortable environment for their socio-economic activities. For the era of fusion and convergence this paper investigated the characteristics of walking accidents related to the aged pedestrians and analyzed the aged-oriented walking factors with a reaction time and a walking speed at crosswalks in Yeosu. In the results, the crashes for the aged occur at 9.9% of total crashes and the fatalities of the aged are 40.3% of total fatalities in 2014. The 47.4% of the aged fatalities is also attributed to vehicle-to-pedestrian accidents. The 49.3% of all pedestrian fatalities occurs at the aged pedestrians with a very high proportion. The reaction time and walking speed for the aged were determined as the values located at the lower 15%-tile of the elderly physical ability. It is shown that the reaction time is 4.56 seconds and the walking speed is 0.76 m/s in the case of Yeosu. From two factors' standpoint, the walking environment at crosswalks in Yeosu is inappropriate for the aged.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.31 no.8
• /
• pp.889-895
• /
• 2007

Quantifying dynamic stability is important to assessment of falling risk or functional recovery for leg injured people. Human locomotion is complex and known to exhibit nonlinear dynamical behaviors. The purpose of this study is to quantify major joints of the body using chaos analysis during walking. Time series of the chaotic signals show how gait patterns change over time. The gait experiments were carried out for ten young males walking on a motorized treadmill. Joint motions were captured using eight video cameras, and then three dimensional kinematics of the neck and the upper and lower extremities were computed by KWON 3D motion analysis software. The correlation dimension and the largest Lyapunov exponent were calculated from the time series to quantify stabilities of the joints. This study presents a data set of nonlinear dynamic characteristics for eleven joints engaged in normal level walking.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.16 no.6
• /
• pp.217-222
• /
• 2007

This paper describes a static gait generation process and a mechanical design process of leg mechanisms for quadruped robots. Actually robot walking is realized with the joint motion of leg mechanisms. In order to calculate the time-angle trajectories for each joint of leg mechanisms, we generate end-tip trajectories with time for each leg in the global inertial coordinate system intuitively, followed by coordinate transformations of the trajectories into the local coordinates system fixed in each leg, finally the angle-time trajectories of each joint of leg mechanisms are obtained with inverse kinematics. The stability of the gait generated in this paper was verified by a multi-body dynamic analysis using the commercial software $ADAMS^{(R)}$. Additionally the mechanical specifications such as gear reduction ratio, electrical specifications of motor and electrical power consumption during walking have been confirmed by the multi-body dynamic analysis. Finally we constructed a small quadruped robot and confirmed the gait.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.54 no.7
• /
• pp.462-467
• /
• 2005

In this paper, we analyzed normal gait acceleration signal by time series analysis methods. Accelerations were measured during walking using a biaxial accelerometer. Acceleration data were acquired from normal subjects(23 men and one woman) walking on a level corridor of 20m in length with three different walking speeds. Acceleration signals were measured at a sampling frequency of 60Hz from a biaxial accelerometer mounted between L3 and L4 intervertebral area. Each step signal was analyzed using Box-Jenkins method. Most of the differenced normal step signals were modeled to AR(3) and the model didn't show difference for model's orders and coefficients with walking speed. But, tile model showed difference with acceleration signal direction - vertical and lateral. The above results suggested the proposed model could be applied to unit analysis.

• Proceedings of the KIEE Conference
• /
• 1998.11b
• /
• pp.546-548
• /
• 1998

This paper deals with ZMP trajectory generation in multi step walking of IWR-III(Inha Walking Robot) Biped Walking Robot. Biped walking is realized by combining 6-types of pre-defined steps and the actual ZMP can be used as a stability index of a robot. For the good tracking of actual ZMP, desired ZMP trajectory is generated during the whole walking time not for each step. Trajectory generation is performed considering velocities and accelerations of given via points using 5-th order polynomial interpolation method. As a result, balancing joints have a more smooth and continuous motion and actual ZMP has a better tracking ability. Numerical simulator is done by MATLAB to guarantee the walking of a robot satisfying the ZMP stability.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2000.10a
• /
• pp.273-280
• /
• 2000

Building structures which are in need of large open space make the damping effect of the structures decrease greatly. Assembly and office buildings with a lower natural frequency have a higher possibility of experiencing excessive vibration induced by human activities. These excessive vibration make the residents uncomfortable and the serviceability deterioration. The loads induced by human activities were classified into two types. First type is in place loads as like jumping, foot stamping and body bouncing. The other type is moving loads as like walking, running and dancing. A series of laboratories experiments had been conducted to study the dynamic loads induced by human activities, The earlier works were mainly concerned to parameters study of dynamic loads as like activity type, weight, sex, surface condition of structure and etc. In this paper, we have measured directly the walking loads by using the platform. And we have evaluated and analyzed load-time history of walking loads. One of the most important parameter is pacing rate (walking speed) in the walking loads. The difference between the maximum value and minimum value of walking loads depends on the walking speed.

• Korean Journal of Applied Biomechanics
• /
• v.27 no.1
• /
• pp.53-58
• /
• 2017

Objective: The purpose of this study was to compare the accuracy of stride time and stride length provided by a commercial APDM inertial sensor system (APDM) with the results of three dimensional motion capture system (3D motion) during treadmill walking. Method: Five healthy men participated in this experiment. All subjects walked on the treadmill for 3 minutes at their preferred walking speed. The 3D motion and the APDM were simultaneously used for extracting gait variables such as stride time and stride length. Mean difference and root mean squared (RMS) difference were used to compare the measured gait variables from the two measurement devices. The regression equation derived from the range of motion of the lower limb was also applied to correct the error of stride length. Results: The stride time extracted from the APDM was almost the same as that from the 3D motion (the mean difference and RMS difference were less than 0.0001 sec and 0.0085 sec, respectively). For stride length, mean difference and RMS difference were less than 0.1141 m and 0.1254 m, respectively. However, after correction of the stride length error using the derived regression equation, the mean difference and the RMS difference decreased to 0.0134 m and 0.0556 m or less, respectively. Conclusion: In this study, we confirmed the possibility of using the temporal variables provided from the APDM during treadmill walking. By applying the regression equation derived only from the range of motion provided by the APDM, the error of the spatial variable could be reduced. Although further studies are needed with additional subjects and various walking speeds, these results may provide the basic data necessary for using APDM in treadmill walking.

• Journal of the Korean Society of Physical Medicine
• /
• v.10 no.4
• /
• pp.25-31
• /
• 2015

PURPOSE: Previous studies have shown that healthy young adults reduced gait velocity during texting or talking while walking. It was reported that increasing number of pedestrian accidents were related to distract the environmental attention. The purpose of this study was to compare the effects of texting and texting while listening to music on gait parameters. METHODS: Texting and listening to music while walking were assessed in two dual-task condition using 35 healthy young adults. The outcome measurements were assessed in terms of spatiotemporal gait parameters in three walking conditions, namely, comfortable walking speed, walking while texting, and walking while texting and listening to music. To avoid learning effect, subjects were individually blinded to assessment schedule and space. The changes between the three walking conditions were analyzed using repeated measures ANOVA. RESULTS: When comparing the two dual-task conditions with the single-task condition, it was found that dual-task interference was increased in almost gait velocity, cadence, stride length, step time, double limb support, and single limb support. In addition, walking while texting and listening to music condition negatively was affected gait speed, stride length, and step time more than the texting only condition. CONCLUSION: Walking while texting and listening to music as well as waling while texting may decrease pedestrian safety when crossing streets by diverting the person's attention away from the street environment.

• Physical Therapy Rehabilitation Science
• /
• v.9 no.4
• /
• pp.222-229
• /
• 2020

Objective: The purpose of this study was to investigate the effect of treadmill exercise on the posture and walking speed of chronic stroke survivors with an ankle-foot orthosis. Design: Randomized controlled trial. Methods: Twenty-four chronic persons with chronic stroke admitted to Bobath Memorial Hospital in Seongnam city were divided into two groups by random blind method. Treadmill exercise with an elastic ankle-foot orthosis was performed in the experimental group and treadmill exercise was performed in the control group. The experiment was carried out for 6 weeks, and the experiment was carried out three times a week for 20 minutes per session. To measure the effect, static balance was measured using the MTD system before and after training, and the Berg Balance Scale (BBS) was used to measure functional balance. Results: There was a statistically significant difference between the 2 groups in the BBS measurement results for confirming the functional balance (p<0.05). Also, there was a significant difference between the 2 groups in single limb support time, step time and step length (p<0.05). Conclusions: In this study, it was found that treadmill exercise with an elastic ankle-foot orthosis in persons with chronic stroke was effective in maintaining functional balance, walking ability, step length, and step time. Therefore, it is necessary to use a flexible ankle-foot orthosis with proper treadmill exercise as a method of improving balance and walking speed of chronic stroke survivors.