• Journal of Positioning, Navigation, and Timing
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• v.9 no.2
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• pp.117-124
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• 2020

In this paper, the symmetric position drift of the integration approach in pedestrian dead reckoning (PDR) system with dual foot-mounted IMU is analyzed. The PDR system that uses the inertial sensor attached to the shoe is called the IA-based PDR system. Since this system is designed based on the inertial navigation system (INS), it has the same characteristics as the error of the INS, then zero-velocity update (ZUPT) is used to correct this error. However, an error that cannot be compensated perfectly by ZUPT exists, and the trend of the position error is the symmetric direction along the side of the shoe(left, right foot) with the IMU attached. The symmetric position error along the side of the shoe gradually increases with walking. In this paper, we analyze the causes of symmetric position drift and show the results. It suggests the possibility of factors other than the error factors that are generally considered in the PDR system based on the integration approach.

• Journal of Korean Physical Therapy Science
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• v.2 no.4
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• pp.739-747
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• 1995

The purpose of this study was to evaluate and compare the Limits of stability(LOS) in hemiplegic patients who can walking independently. The LOS was measured at stable surface, unstable surface with eye open and eye closed. In this study, 18 out-patients were evaluated who were treated at Yonsei University Medical Center Rehabilitation Hospital. In order to determine the statistical significance of results, T-test, paired t-test, and Kruskal-Wallis 1-way ANOVA were applied at 0.05 level of significance. The results were as follows: 1. The mean of lateral limits of stability was 9.89 degree. 2. The mean of anteroposterior limits of stability was 6.43 degree. 3. There was a significant difference of limits of stability between sound side and affected side(p<0.05). 4. The limits of stability was significantly decreased with eye closed(p<0.05) 5. The limits of stability was significantly decreased at unstable surface(p<0.05). 6. The limits of stability was a significant difference as spasticity degree of ankle plantar flexors(p<0.05). These results showed that the limits of stability in hemiplegic patients was more decreased than that of normal adult. In order to improve the balance in hemiplegic patients, we need to increase the limits of stability.

• Journal of Biosystems Engineering
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• v.32 no.2 s.121
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• pp.91-96
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• 2007

In this study, a prototype remote controlled weeder using solar module was developed and the evaluations of weeding, side walking and weeding performance were conducted to see if actual application was feasible in the paddy field. When traveling, the loss electric current was 8 to 15 A depending on operating and soil conditions. The average traveling speed was 0.25 m/s and the average slippage was 18%. When it side walked row by row, electric current consumption was 7 A on the average. When wheel rotors line went initially up and last down, electric current consumption was 12 to 15 A due to soil resistance. Electric current consumption when shifting wheel rotors line was less than 5 A due to no resistance. Field efficiency was 105 min/10a based on the test field. Operation was able to be done for 4.16 hours continually by 52 AH battery based on 300 W average maximum power consumption and 4.6 hours under sunny day considering solar module.

• Physical Therapy Korea
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• v.20 no.4
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• pp.40-46
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• 2013

The purpose of this study was to determine which spatiotemporal gait parameters obtained during hemiplegic walking could be a predictive factor for the Timed Up and Go test (TUG). Two hundreds nine subjects who had suffered a stroke were recruited for this study. They were participated in two assessments; the TUG test and gait analysis. The relationship between the TUG test and spatiotemporal parameters was analyzed using Pearson's correlation coefficients. In addition, to predict the spatiotemporal gait parameters that correlated most with the TUG scores, we used multiple linear regression analyses (stepwise method). The results show that the normalized velocity was strongly correlated with the TUG performance (r=-.72, p<.001). Additionally, single support percentage (SSP), double support percentage (DSP), step time difference (STD), and step length difference (SLD) significantly were correlated with the TUG test. Normalized velocity, STD, DSP of affected side, and SSP of non-affected side explained 53%, 8%, 3%, 2%, of variance in the TUG test respectively. In conclusion, an increase in gait velocity and a decrease in STD would be effective indicators of improvement on the functional mobility in the stroke rehabilitation.

• Physical Therapy Korea
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• v.20 no.1
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• pp.64-73
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• 2013

The purposes of this study were to develop a new orthosis controlling ankle and knee joint motion during the gait cycle and to identify the effects of the newly designed orthosis on gait kinematics and tempospatial parameters, including coordination of the extremities in stroke patients. Fifteen individuals who had sustained a stroke, onset was 16 months, participated in this study. Before application of the measurement equipment the subjects were accustomed to walking on the ankle-foot orthosis (AFO) or stance control knee with knee flexion assisted-oil damper ankle-foot orthosis (SCKAFO) for 5 minutes. Fifteen patients were investigated for 45 days with a 3-day interval between sessions. Measurements were walking in fifteen stroke with hemiparesis on the 3D motion analysis system. Comparison of AFO and SCKAFO are gait pattern. The difference between the AFO and SCKAFO conditions was significant in the gait velocity, step length of the right affected side, stance time of both legs, step-length asymmetry ratio, single-support-time asymmetry ratio, ${\phi}$-thigh angle and ${\phi}$-shank angle in the mid swing (p<.001). Using a SCKAFO in stroke patients has shown similar to normal walking speeds can be attained for walking efficiency and is therefore desirable. In this study, the support time of the affected leg with the SCKAFO was longer than with the AFO and the asymmetry ratio of single support time decreased by more than with the AFO. This indicates that the SCKAFO was effective for improving gait symmetry, single-support-time symmetry. This may be due to the decrease of gait asymmetry. Thus, the newly designed SCKAFO may be useful for promoting gait performance by improving the coordination of the extremity and decreasing gait asymmetry in chronic stroke patients.

• Korean Journal of Applied Biomechanics
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• v.16 no.3
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• pp.137-148
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• 2006

The purpose of this study was to compare muscle activity in the lower extremity during walking wearing jogging and roller shoes. Twelve male middle school students (age: 15.0 yrs, height 173.7 cm, weight 587.7 N) who have no known musculoskeletal disorders were recruited as the subjects. Seven pairs of surface electrodes (QEMG8, Laxtha Korea, gain = 1,000, input impedance >$1012{\Omega}$, CMMR >100 dB) were attached to the right-hand side of the body to monitor the rectus femoris (RF), vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF), tibialis anterior (TA), and medial (GM) and lateral gastrocnemius (GL) while subjects walked wearing roller and jogging shoes in random order at a speed of 1.1 m/s. An event sync unit with a bright LED light was used to synchronize the video and EMG recordings. EMG data were filtered using a 10 Hz to 350 Hz Butterworth band-passdigital filter and further normalized to the respective maximum voluntary isometric contraction EMG levels. For each trial being analyzed, five critical instants and four phases were identified from the recording. Averaged IEMG and peak IEMG were determined for each trial. For each dependent variable, paired t-test was performed to test if significant difference existed between shoe conditions (p<.05). The VM, TA, BF, and GM activities during the initial double limb stance and the initial single limb stance reduced significantly when going from jogging shoe to roller shoe condition. The decrease in EMG levels in those muscles indicated that the subjects locked the ankle and knee joints in an awkward fashion to compensate for the imbalance. Muscle activity in the GM for the roller shoe condition was significantly greater than the corresponding value for the jogging shoe condition during the terminal double limb stance and the terminal single limb stance. Because the subjects tried to keep their upper body weight in front of the hip to prevent falling backward, the GM activity for the roller shoe condition increased. It seems that there are differences in muscle activity between roller shoe and jogging shoe conditions. The differences in EMG pattern may be caused primarily by the altered position of ankle, knee, and center of mass throughout the walking cycle. Future studies should examine joint kinematics during walking with roller shoes.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.1
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• pp.74-81
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• 2016

Because most of the passengers are not accustomed with onboard environments, it is very important to analyze and predict the behaviors' characteristics of passengers under disasters' conditions, and apply those results for making countermeasures. On this view point, this study focused on the walking characteristics of onboard-novices are tested and analyzed under blackout condition that has high possibility to happen. As a result, comparing to under normal lighting conditions, the waking times under blackout conditions are 155.8~247.1 % longer on full path, 56.9~331.7 % on corridors, 75.3~152.9 % on stairs, respectively. And under the same blackout conditions, walking times in cases of the exit guidance marks being attached on top side of walls saved times, like 21.6~24.0 % on full path, 37.7~58.9 % on corridors, 18.7~19.2 % on stairs, comparing to the cases of exit guidance marks being not attached. On the other hand, after tests under without exit guidance marks, 60.7% among respondents answered that internal structures like wall/stair (35.7 %) and handrail (25 %) are very helpful to decide way findings, and 28.6 % selected personal instincts is important. But 50 % responded that exit guide marks are effective to find ways, after the tests under with exit guidance marks.

• Journal of the Korean Society of Physical Medicine
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• v.17 no.2
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• pp.53-62
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• 2022

PURPOSE: This study was conducted to investigate the effect of a real-time pressure feedback provided during gait training on the weight weight distribution of the inner part of mid-foot in paralyzed side and gait function in stroke patients. METHODS: A total of 24 patients with hemiplegic stroke in a rehabilitation hospital were randomly assigned to the experimental and control group. All participants (n = 24) performed 15 min of comprehensive rehabilitation therapy 5 times a week for a period of 4 weeks. Additionally, the experimental group and control group underwent gait training with a real time feedback and general gait training, respectively, for 15 min five times a week for 4 weeks. Weight distribution and gait function were measured before and after the 4-week training. RESULTS: Significant increases in the weight distribution (WD), stance time (ST) and step length (SL) of the paralyzed side, and a significant decrease in the 10 m walking test (10 MWT) observed after training in the two groups (p < .05). The experimental group showed larger changes in the all variables than the control group (WD, +10.5 kg vs. +8.8 kg, p < .05; ST, 12.8 s vs. 4.9 s, p < .05; SL, 4.9 cm vs. 1.7 cm, p < .05; 10 MWT, -3.5 s vs. -1.0 s, p < .05, respectively). CONCLUSION: Gait training with a real-time feedback might be effective in improving the normalization of weight bearing of the paralyzed lower extremity and gait function of stroke patients, and be considered to be a more effective gait training for improving the abilities than the general gait training.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.231-236
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• 2005

As number of old and handicapped passengers is increasing in an aging society, it is becoming more and more important to provide safe and convenient subway interior design and direction. In this research, we study basic indispensable conditions for subway chair and propose a chair design direction for old and handicapped people considering their use. In this study, we elicit the rational result based on analysis of Seoul subway design direction. This study should be expanded into universal design for not only old people but also pregnant people and children. The chair for old people is needed to have side partitions and a safety bar for safe walking and to be made of soft materials which has some cushion.

• Clinical and Experimental Pediatrics
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• v.59 no.sup1
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• pp.157-160
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• 2016

Coexistence of paroxysmal kinesigenic dyskinesia (PKD) with benign infantile convulsion (BIC) and centrotemporal spikes (CTS) is very rare. A 10-year-old girl presented with a 3-year history of frequent attacks of staggering while laughing and of suddenly collapsing while walking. Interictal electroencephalogram (EEG) revealed bilateral CTS, but no changes in EEG were observed during movement. The patient's medical history showed afebrile seizures 6 months after birth, while the family history showed that the patient's mother and relatives on the mother's side had similar dyskinesia. Genetic testing demonstrated that the patient had a heterozygous mutation, c.649_650insC, in the PRRT2 gene. To our knowledge, this constitutes only the second report of a patient with PKD, BIC, CTS, and a PRRT2 mutation.