• Safety and Health at Work
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• v.3 no.1
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• pp.22-30
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• 2012

Objectives: To challenge the problem of slipperiness, various slipmeters have been developed to assess slip hazard. The performance of in-situ slipmeter is, however, still unclear under the various floor conditions. The main objectives of this study were to evaluate the performance of three kinds of slipmeters under real conditions, and to find their dynamic and kinematic characteristics, which were compared with gait test results. Methods: Four common restaurant floor materials were tested under five contaminants. Slipmeters and human gaits were measured by high speed camera and force plate to find and compare their dynamic and kinematic characteristics. Results: The contact pressures and built-up ratio were below those of subjects. The sliding velocity of British Pendulum Tester was above those of subjects, while those of BOT-3000 and English XL were below those of subjects. From the three meters, the English XL showed the highest overall correlation coefficient (r = 0.964) between slip index and $R_a$, while the rest did not show statistical significance with surface roughness parameters ($R_a$, $R_z$). The English XL only showed statistical significance (p < 0.01) between slip index and contaminants. The static coefficient of friction obtained with the BOT-3000 showed good consistency and repeatability (CV < 0.1) as compared to the results for the BPT (CV > 0.2) and English XL (CV < 0.2). Conclusion: It is unclear whether surface roughness can be a reliable and objective indicator of the friction coefficient under real floor conditions, and the viscosity of contaminants can affect the friction coefficient of the same floors. Therefore, to evaluate slipperiness, the performance of the slipmeters needed to improve.

• The Journal of the Korea Contents Association
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• v.13 no.10
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• pp.444-451
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• 2013

The purpose of this study was to investigate the changes in temporospatial variables in healthy elderly and healthy adults during usual walking, narrow base walking and centerline-guided walking. Twenty healthy elderly and nineteen healthy adults were participated in this study. In each conditions, the subjects were walked on a 6m walkway at comfortable self-selected speeds under three conditions : (1) usual walking, (2) walking within a 50% of the distance between the subject's ASIS (3) walking along a centerline. GAITRite system was used for kinematic analysis to assess the temporospatial variables. There were no significant changes in healthy adults(p>.05), but walking speed, cadence, H-H base support, functional ambulation performance were significantly decreased progressively as pathway narrowed in elderly adults(p<.05). The results show that elderly people had more difficulty with walking on narrow pathway for fear of falling. This study provides data for use in basic research into safe walking and preventing falling for elderly.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.6
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• pp.585-592
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• 2014

In this study, a multibody simulator was developed to analyze the bio-mimetic motion of a lizard robot design. A RecurDyn multibody dynamics model of a lizard was created using a micro-computerized tomography scan and motion capture data. The bio-mimetic motion simulator consisted of a trajectory generator, an inverse kinematics module, and an inverse dynamics module, which were used for various walking motion analyses of the developed lizard model. The trajectory generation module produces spinal movements and gait trajectories based on the lizard's speed. Using the joint angle history from an inverse kinematic analysis, an inverse dynamic analysis can be carried out, and the required joint torques can be obtained for the lizard robot design. In order to investigate the effectiveness of the developed simulator, the required joint torques of the model were calculated using the simulator.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6767-6773
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• 2014

The study examined the effects of trunk pattern exercise in proprioceptive neuromuscular facilitation (PNF) integrated transcranial direct current stimulation (tDCS) on the muscle activity and balance, walking speed in stroke patient. Thirty-one patients with hemiplegia due to stroke were assigned to either the experimental group (n=15) or control group (n=16). Both groups performed trunk pattern training in PNF for 3 times per week over a 6 week period for 20 minutes per session. The experimental group performed additional tDCS for 20 minutes. A comparison of the two groups after the intervention showed that the exercise program in experimental group had a more significant on the gastrocnemius, tibialis anterior and balance than the control group (p<.05). This showed that trunk pattern exercise in PNF integrated tDCS had a positive effect on the functional recovery of the lower extremity in stroke patients.

• Journal of Korean Physical Therapy Science
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• v.15 no.2
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• pp.87-95
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• 2008

Background: Hemiplegic patients usually have difficulty maintaining balance. Balance training is a major component of there habilitation program for patients with neurological impairment. The purpose of this study was to investigate the effects of PLS(Posterior Leaf Spring), FES(Functional Electrical stimulation), treadmill training, and neurodevelopmental treatment on the improvement of balance in patients with hemiplegia. Methods: We looked into published studies from Dankook University’s electronic library databases of RISS4U, KMbase, NCBI, and MEDLIS concerning the effectiveness of any form of intervention leading to improvement of balance. All types of studies relevant to the topic that were published in English during the time period of 1986 to 2005 were included. Results: 1. There were significant differences in standing balance, dynamic activity balance, and gait speed between barefoot subjects and subjects who wore SPAFO and HPAFO(p<.05). 2. The changes in ROM and FRT related to sex, age, height, and weight part of the diagnosis, as well as experience relapse, was of meaningless value. Changes in ROM related to the duration of pain and experiences of falling down were also meaningless. However, FRT showed significant static differences(p<.05). 3. The body-weight-support treadmill training scoring of standing balance, step length, and a timed 10m walking test showed definite improvement. 4. The proprioceptive control approach improved dynamic balance in patients with hemiplegia. Conclusion: Consequently, further study is needed to verify methods when physical therapists are researching balance ability in hemiplegic patient.

• Physical Therapy Rehabilitation Science
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• v.4 no.2
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• pp.115-120
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• 2015

Objective: To examine the effects of different shoe weights on lower leg muscle fatigue when walking by electromyographic (EMG) analysis due to the most effective weight for loading not being established. Design: Cross-sectional study. Methods: Thirty healthy university students (15 male, 15 female) were enrolled and randomly assigned into three conditions, which included wearing athletic shoes with an addition of 300 g, 500 g, and 1,000 g weights respectively. Prior to walking, all subjects were instructed to sit in a chair for 10 minutes. All subjects walked at a speed of 3.6 m/s on a treadmill for 20 minutes without rest. EMG measurements were taken using the median power frequency to assess for the effect of the different weight of shoes on muscle fatigue of the soleus, gastrocnemius, and tibialis anterior while walking on a treadmill in an upright posture. EMG measurements were taken during the first and last 30 seconds of walking. Results: In terms of muscle fatigue, for the soleus, the median power frequency was significantly lower with 1,000 g compared with 300 g and 500 g (p<0.05). For the tibialis anterior, the median power frequency was significantly lower with 1,000 g than 300 g and 500 g (p<0.05). For the gastrocnemius, the median power frequency was significantly lower with 1,000 g compared with 300 g (p<0.05). Conclusions: Increased shoe weight increases soleus, gastrocnemius, and tibialis anterior muscle fatigue during ambulation.

• Journal of the Ergonomics Society of Korea
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• v.35 no.5
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• pp.319-341
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• 2016

Objective:This research analyzed the lower-limb motion in kinetic and kinematic way while walking on various terrains to develop Foot-Ground Contact Detection (FGCD) algorithm using the Inertial Measurement Unit (IMU). Background: To estimate the location of human in GPS-denied environments, it is well known that the lower-limb kinematics based on IMU sensors, and pressure insoles are very useful. IMU is mainly used to solve the lower-limb kinematics, and pressure insole are mainly used to detect the foot-ground contacts in stance phase. However, the use of multiple sensors are not desirable in most cases. Therefore, only IMU based FGCD can be an efficient method. Method: Orientation and acceleration of lower-limb of 10 participants were measured using IMU while walking on flat ground, ascending and descending slope and stairs. And the inertial information showing significant changes at the Heel strike (HS), Full contact (FC), Heel off (HO) and Toe off (TO) was analyzed. Results: The results confirm that pitch angle, rate of pitch angle of foot and shank, and acceleration in x, z directions of the foot are useful in detecting the four different contacts in five different walking terrain. Conclusion: IMU based FGCD Algorithm considering all walking terrain possible in daily life was successfully developed based on all IMU output signals showing significant changes at the four steps of stance phase. Application: The information of the contact between foot and ground can be used for solving lower-limb kinematics to estimating an individual's location and walking speed.

• Journal of Broadcast Engineering
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• v.25 no.5
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• pp.734-741
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• 2020

This article proposes a new pedestrian avoidance algorithm for social robots that coexist and communicate with humans and do not induce stress caused by invasion of psychological safety distance(Social Distance). To redefine the pedestrian model, pedestrians are clustered according to the pedestrian's gait characteristics(straightness, speed) and a social distance is defined for each pedestrian cluster. After modeling pedestrians(obstacles) with the social distances, integrated navigation algorithm is completed by applying the newly defined pedestrian model to commercial obstacle avoidance and path planning algorithms. To show the effectiveness of the proposed algorithm, two commercial obstacle avoidance & path planning algorithms(the Dynamic Window Approach (DWA) algorithm and the Timed Elastic Bands (TEB) algorithm) are used. Four cases were experimented in applying and non-applying the new pedestrian model, respectively. Simulation results show that the proposed algorithm can significantly reduce the stress index of pedestrians without loss of traveling time.

• Journal of International Academy of Physical Therapy Research
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• v.6 no.1
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• pp.788-794
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• 2015

This study examines changes in walking ability among patients with stroke after applying dual-task training under the condition of visual control and unstable supporting ground; the purpose is to provide reference data for selecting intervention methods that enhance the walking ability of patients with stroke. Among the patients with stroke who received rehabilitation treatment(at Rehabilitation Hospital B in Gyeonggi, South Korea from May 2014 to July 2014), 29 patients were selected as research subjects; all of them understood the purpose and contents of this research and agreed to participate in the experiment. The research subjects were divided into a visual control and unstable supporting ground dual-task(VUDT) group(10 patients), a visual control dual-task(VDT) group(10 patients), and an unstable supporting ground dual-task(UDT) group(9 patients); all of the subjects received 30-minute trainings, three times a week for a total of four weeks. A Timed-Up-and-Go(TUG) test was performed to investigate the change of walking function among the subjects, and a 10m walking test was conducted to measure their walking speed. According to the study results, all three groups showed significant differences after dual-task training; the dual-task training group under the condition of visual control and unstable supporting ground showed the most prominent change. This study confirmed that dual-task training using visual control and unstable supporting ground has a positive impact on the walking ability of patients with stroke. Through the study results, we found that implementing dual-task training under the condition of visual control and unstable supporting ground can more effectively improve the walking ability of patients with stroke, rather than performing visual control dual-task training or unstable supporting ground dual-task training only.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.14 no.1
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• pp.39-47
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• 2008

Purpose : The purpose of this study was to investigate the change of the peak plantar pressure distribution under the foot areas and the range of motion (ROM) of ankle joint according to gradients in treadmill gait. Method : Thirty normal subjects (15 male and 15 female) walked on treadmill at three gradient conditions ($0^{\circ}$, $10^{\circ}$, and $15^{\circ}$) in normal speed. The ankle ROM was measured using the CMS70P that is three dimensional analyzer for excursion of ankle ROM, plantar flexion, and dorsi flexion. The peak plantar pressure distribution under the hallux, 1st metatarsal head (MTH) and heel was measured using the F -Scan system with an in-shoe sensor. Data was collected from 9 steps of left sife foot in at each gradient condition while all subjects walked. Result : As the treadmill gradient increased, the excursion of ankle joint was significantly increased (p<.05). Also, plantar flexion and dorsi flexion was significantly increased according to treadmill gradients (p<.05). The peak plantar pressure under the 1st MTH was significantly increased (p<.05) and the peak plantar pressure under the heel was significantly decreased (p<.05) as the treadmill gradient increased. No significant different in the peak plantar pressure under the hallux was observed. Conclusion : This study suggests that physical therapy for patients who have limited ankle ROM should be considered sufficient range of motion for functional ambulation. And individuals that have painful forefoot syndromes, including metatarsalgia, hallux valgus, and plantar ulceration should be careful in walking to uphill, as there is high plantar pressure under the forefoot.