• Korean Journal of Applied Biomechanics
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• v.25 no.2
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• pp.191-198
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• 2015

Objective : The purpose of this study was to conduct biomechanical analysis of varying backpack loads on the lower limb movements during downhill walking over $-20^{\circ}$ ramp. Method : Thirteen male university students (age: $23.5{\pm}2.1yrs$, height: $175.7{\pm}4.6cm$, weight: $651.9{\pm}55.5N$) who have no musculoskeletal disorder were recruited as the subjects. Each subject walked over $20^{\circ}$ ramp with four different backpack weights (0%, 10%, 20% and 30% of body weight) in random order at a speed of $1.0{\pm}0.1m/s$. Five digital camcorders and two force plates were used to obtain 3-d data and kinetics of the lower extremity. For each trial being analyzed, five critical instants were identified from the video recordings. Ground reaction force, loading rate, decay rate, and resultant joint moment of the ankle and the knee were determined by the inverse dynamics analysis. For each dependent variable, one-way ANOVA with repeated measures was used to determine whether there were significant differences among four different backpack weight conditions (p<.05). When a significant difference was found, post hoc analyses were performed using the contrast procedure. Results : The results of this study showed that the medio-lateral GRFs at RHC in 20% and 30% body weight were significantly greater than the corresponding value in 0% of body weight. A consistent increase in the vertical GRFs as backpack loads increased was observed. The valgus joint movement of the knee at RTO in 30% body weight was significantly greater than the corresponding values in 0% and 10% body weight. The increased valgus moment of 30% body weight observed in this phase was associated with decelerating and stabilizing effects on the knee joint. The results also showed that the extension and valgus joint moments of the knee were systematically affected by the backpack load during downhill walking. Conclusion : Since downhill walking while carrying heavy external loads in a backpack may lead to excessive knee joint moment, damage can occur to the joint structures such as joint capsule and ligaments. Therefore, excessive repetitions of downhill walking should be avoided if the lower extremity is subjected to abnormally high levels of load over an extended period of time.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.8 no.2
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• pp.33-37
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• 2010

Purpose : We investigated the effects of the insole types on lower leg muscle activation during treadmill walking. The three insole types investigated for this study were normal insole, medial wedge insole, and viscoheel. Methods : Participants were assigned into three groups. People with foot transformation were excluded from this study. Each participant walked for ten minutes. The first day we applied a normal insole. On the second day, a medial wedge insole was applied. Finally, on the last day a viscoheel was applied. After walking on a treadmill for ten minutes, we measured muscle activation in lower leg muscles (gastrocnemius and tibialis anterior). Surface electromyography (EMG) was used to measure muscle activity. The data were analyzed using one-way analysis of variance (ANOVA) with repeated measures to determine the statistical significance. Results : The results of this study were summarized as follows. While walking on the treadmill, root mean square (RMS) values of the gastrocnemius when the viscoheel was applied were significantly lower than the other insole types. There was no significant difference for the RMS values for the tibialis anterior using viscoheel. The normal insole and viscoheel insole were significantly different in a post hoc analysis. However, there was no significant difference for normal insole and medial wedge insole. Conclusion : Using a viscoheel insole decreases muscle activity of the lower leg. Therefore, in conclusion, the viscoheel insole type reduces the load on the lower leg during walking.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1934-1937
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• 2005

This paper proposes suitable gait generation for dynamic walking of biped robot with varying load in real time. Author proposes the relationship between ZMP(Zero Moment Point) and measurement from FSR(Force Sensing Register). Simplifying this relationship, it is possible to reduce the computational time and control the biped robot in real time. If the weight of the biped robot varies in order to move some object, then joint trajectories of the the biped robot must be changed. When some object is loaded on the biped robot in it's home position, FSRs can measure the variation of weight. Evaluating the relations between varying load and stable gait of the biped robot, it can walk adaptively. This relation enables the biped robot to walk properly with varying load. The simulation is also represented in this paper which shows proposed relationships.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.9
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• pp.825-837
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• 2017

This paper describes a novel type of a walking rehabilitation robot that applies robot technologies to crutches used by patients with walking difficulties in the lower body. The primary features of the developed robot are divided into three parts. First, the developed robot is worn on the patient's chest, as opposed to the conventional elbow crutch that is attached to the forearm; hence, it can effectively disperse the patient's weight throughout the width of the chest, and eliminate the concentrated load at the elbow. Furthermore, it allows free arm motion during walking. Second, the developed robot can recognize the walking intention of the patient from the magnitude and direction of the ground reactive forces. This is done using three-axis force sensors attached to the feet of the robot. Third, the robot can perform a stair walking function, which can change vertical movement trajectories in order to step up and down a single stair according to the floor height. Consequently, we experimentally showed that the developed robot can effectively perform walking rehabilitation assistance by perceiving the walking intention of the patient. Moreover we quantitatively verified muscle power assistance by measuring the electromyography (EMG) signals of the muscles of the lower limb.

• Structural Engineering and Mechanics
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• v.63 no.6
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• pp.771-777
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• 2017

The applications of smartphones or other portable smart devices have dramatically changed people's lifestyle. Researchers have been investigating useage of smartphones for structural health monitoring, earthquake monitoring, vibration measurement and human posture recognition. Their results indicate a great potential of smartphones for measuring pedestrian-induced loads like walking, jumping and bouncing. Smartphone can catch the device's motion trail, which provides with a new method for pedestrain load measurement. Therefore, this study carried out a series of experiments to verify the application of the smartphone for measuring human-induced load. Shaking table tests were first conducted in order to compare the smartphones' measurements with the real input signals in both time and frequency domains. It is found that selected smartphones have a satisfied accuracy when measuring harmonic signals of low frequencies. Then, motion capture technology in conjunction with force plates were adopted in the second-stage experiment. The smartphone is used to record the acceleration of center-of-mass of a person. The human-induced loads are then reconstructed by a biomechanical model. Experimental results demonstrate that the loads measured by smartphone are good for bouncing and jumping, and reasonable for walking.

• Composites Research
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• v.34 no.6
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• pp.400-405
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• 2021

In this study, a composite material frame was designed to increase the energy harvesting efficiency of polyvinylidene fluoride (PVDF) ribbon harvesters which are installed inside smart shoes. In order to minimize the amount of deformation in the load direction of the frame, it was designed using carbon continuous fiber composites and its complex shaped structure was manufactured using a 3D printer. In order to calculate the amount of deformation of the insole and midsole of the shoes under the condition of the load generated during walking, the insole and midsole were modeled using the distributed spring elements. Using finite element analysis, the elongation of ribbon-type harvesters mounted on smart shoes was calculated during walking. It is expected that the predicted elongation of the harvester can be utilized to increase the energy harvesting efficiency of smart shoes.

• Journal of Preventive Medicine and Public Health
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• v.17 no.1
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• pp.281-287
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• 1984

In search for a method of evaluating the cardiopulmonary function. 74 male and 33 female volunteers ages $18{\sim}25$ were subjected to this study The subjects walked on a treadmill at speed of 2,4,6 and 8km/hr with 0,5,10,15,20 and 25% grade of inclination, respectively, for a measurement of heart rate and oxygen-pulse. Heart rate was measured every 5 seconds at resting state and during walking by telemetric method using Heart Checker 108 System (Senoh Co., Japan). Oxygen concentration was measured by Douglas bag method collecting expired air for 5 minutes at rest, and for 2 minutes at the end of each walking exercise. Oxygen concentration in an expired air was analyzed with Orzat gas analyser and expressed in terms of STPD. Oxygen-pulse was defined as an amount of oxygen consumed at every heart at a cellular level. The followings were the results obtained from this study. 1. Mean values of oxygen-pulse at resting state was $3.1{\pm}0.11ml/beat$ in male and $2.5{\pm}0.87ml/beat$ in female, respectively. 2. Mean values of oxygen-pulse during treadmill walking were increased in proportion with the load of exercise, namely, the speed and grade of inclination, from minimum of 7.1ml/beat upto maximum of 18.2ml/beat in male and from minimum of 4.2ml/beat upto maximum of 12,7ml/beat in female. 3. Both linear and logarithmic regressional relationships between oxygen-pulse and speed of walking and grade of inclination were observed in both sexes. Predicted values of oxygen-pulse by logarithmic regressional formula on speed and on grade of inclination were better coincided with the measured values than those predicted by the linear regressional formula.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.10 no.1
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• pp.65-72
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• 2016

In this study, a fully active transfemoral prothesis with a knee joint is designed considering stair walking conditions. Since the torque at the knee joint required for stair walking condition is relative high compared with the one in normal walking condition, the proposed design has high torque generating mechanism. Moreover, the transfemoral prothesis is designed in compact size to reduce its weight, which is related to comfortable fit and fatigue of patients. Flat type BLDC motor is used for simple and compact structure and various components are used to generate required torque with target working angle and speed. The weight reduction of structure is carried out using optimization method after the initial design process is complete. The optimization is conducted under the load conditions of stair walking. The optimized design is validated via finite element analysis and experiments. As a result, the weight is reduced using topology and shape optimization but maintaining the safety of structure. Also the space efficiency is improved due to its compact size.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2660-2664
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• 2003

In this study, the concept of autonomous mobility is applied to a medical service robot. The aim of the development of the service robot is for the elderly assisting walking rehabilitation. This study aims that the service robot design parameter is proposed in ergonomic view. The walking assistant path pattern is derived from analyzing the elderly gait analysis. A lever is installed in the AMR in order to measure the pulling force and the leading force of the elderly. A lever mechanism is applied for walking assistant service of the AMR. This lever is designed for measuring the leading force of the elderly. The elderly adjusts the velocity of the robot by applying force to the lever. The action scope and the service mechanism of the robot are developed for considering and analyzing the elderly action patterns. The ergonomic design parameters, that is, dimensions, action scope and working space are determined based on the elderly moving scope. The gait information is acquired by measuring the guide lever force by load cells and working pattern by the electromyography signal.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.1
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• pp.5-13
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• 2017

Noise complaints among neighbors in apartment building are mainly caused by floor impact noise that is structure born noise due to occupant induced floor vibration. To control this noise problems many researchers have investigated floor systems and finishing materials. Light-weight impact noise affects by finishing materials, but heavy-weight impact noise induced by heel impacts during normal walking or jumping of children is concerned with structural system and floor vibration. To figure out the characteristics of floor impact noise and transmission of floor vibration due to human activities, vibration tests were conducted in apartment buildings. Impact hammer, heel drop and walking activities were loaded at center of upstairs living room, and accelerations of slabs for both upstairs and downstairs and sound pressure levels for downstairs were measured. The acceleration ratio of transmitted floor vibration to downstairs and human induced vibration in upstairs was between 0.5 and 1.0 according to slab size, wall, and load type. And floor impact noise occurred in the range of natural frequency of slab.