• Korean Journal of Applied Biomechanics
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• v.16 no.4
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• pp.83-94
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• 2006

The purpose of this study is to elucidate how walking speed influences on change of angles of lower extremity and ground reaction force in normal and obese people. One group with normal body weight who were experimented at a standard speed of 1.5m/s and the other obese group were experimented at two different walking speeds (standard speed of 1.5m/s and self-selected speed of 1.3m/s). We calculated angles of lower extremity and ground reaction force during stance phase through video recording and platform force measuring. When the obese group walked at the standard speed, dorsi-flexion angle of ankle got bigger and plantar-flexion angle of ankle got smaller, which were not statistically significant. There was no significant difference of knee joint angles between normal and obese group at the same speed walking but significant post hoc only for the first flexion of knee joint in obese group. $F_z1$ was bigger than $F_z3$ in vertical axis for ground reaction force in both groups at the standard speed walking and the same force value at self-selected speed in obese group. $F_y3$ was always bigger than $F_y1$ in anterior-posterior axis in both groups.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.459-466
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• 2001

The floor vibration aspect for building structures which are in need of large open space are influenced by the interrelation between natural frequency and working loads. Structures with a long span and low natural frequency have a higher possibility of experiencing excessive vibration induced by dynamic excitation such as human activities. These excessive vibrations make the residents uncomfortable and the serviceability deterioration. Need formulation of loads data through actual measurement to apply walking loads that is form of dynamic load in structure analysis. The loads induced by human activities were classified into two types. First type is in place loads. the other type is moving loads. 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. In this Paper, the walking loads have been directly measured by using the measuring plate in which two load cells were placed, the parameters, the load-time history of walking loads, and the dynamic load factors have been analyzed. Moreover, the shape of the harmonic loads which were gotten by decomposition the walking loads have been analyzed , and the walking loads modeling have been carried out by composition these harmonic loads derived by functional relation.

• 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.

• Physical Therapy Korea
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• v.14 no.3
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• pp.23-31
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• 2007

The purpose of this study was to determine the influence of high-heeled shoes on walking of obese women as it was already proven an extrinsic factor of knee osteoarthritis in women with normal weight. In this study the aimed therefore in particular was to utilize high-heeled shoes in proving it's causal influence on knee osteoarthritis by measuring the angle and torque of the knee joint. Fifteen obese women (BMI>25 $kg/m^2$) were measured in their twenties. Each angle and torque of their knee joints during walking on 6.5 cm high-heeled shoes and with a bare feet, were compared with each other and analyzed with a 3D motion analysis system. There was no significant difference in walking speed, cadence and stride length between the two conditions. However, there was a significant increase in a double limb support time and the stance phase when walking on high-heeled shoes as when walking with bare feet. The peak knee flexion angle and peak knee varus torque was higher when walking on high-heeled shoes than with bare feet. On the contrary, the peak knee flexion angle in the swing phase was not statistically different. The prolongation of peak knee varus torque was also proven. There was a significant increase in peak knee varus torque in the initial and last stance phases during walking on high-heeled shoes as compared to walking on bare feet. Through the above results, it was proven that when obese women walked on high-heeled shoes, rather than with bare feet, peak knee flexor and varus torque increased along with the changes of the in knee joint angle. Therefore, the influence of high-heeled shoes might be a significant intrinsic factor in knee osteoarthritis of obese women.

• Journal of Sensor Science and Technology
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• v.26 no.2
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• pp.114-121
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• 2017

This paper describes the design and fabrication of a three-axis force sensor with parallel plate beams (PPSs) for measuring the calf force while a patient with a walking assist robot is walking. Current walking assist robots can't measure the weight of the patient's leg and the robot's leg which required for robot control. So, the three-axis force sensor in the calf link is designed and manufactured, it is composed of a Fx force sensor, a Fy force sensor and a Fz force sensor. The three-axis force sensor was designed using by FEM(Finite Element Method), and fabricated using strain-gages. The characteristics experiment of the three-axis force sensor was carried out respectively. The test results indicated that the repeatability error and the non-linearity error of three-axis force sensor was less than 0.04% respectively. Therefore, the fabricated three-axis force sensor in the calf link can be used to measure the patient's calf force in the walking assist robot.

• 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.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1157-1160
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• 1996

Control of a biped robot which has compliant ankle joints is dealt in this paper. Simulated version of a human ankle joint is built using springs and mechanical constraints, which gives a flexibility of joint and compliance against the touching ground. The biped robot with compliant ankle joints proposed here gives a good contact between its sole and the ground and makes foot landing soft. As a result, installing force sensors for measuring the center of gravity of the biped becomes easier. A motor to drive an ankle joint is not needed which makes legs light. However, the control problem becomes more difficult because the torque of the ankle joint to put the biped in a desired walking gait cannot be provided from the compliant ankle joint. To solve this problem, we proposed a dynamic gait modification method by adjusting the position of a hip joint. Simulation results for the mathematical model of the SD-2 biped in the Ohio State University are given to show the validity of the proposed controller.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.117-124
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• 2003

Long span structures with low natural frequencies such as shopping malls, large offices, and assembly rooms may experience signification dynamic responses due to human activities. In this study, equations to estimate the magnitudes of group walking loads are derived and a simple procedure to estimate and evaluate the corresponding response of the existing and new building structures subjected to human loads is proposed. The effectiveness of the proposed method is verified analytically using a simple floor and experimentally on a footbridge measuring the structural response induced by group pedestrians. Results indicate that the amplitudes of group walking loads can be easily estimated if the mode shapes are available, and that the corresponding structural responses can be estimated easily by the simple response measurement using the proposed method.

• Journal of Korea Multimedia Society
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• v.22 no.1
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• pp.62-69
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• 2019

In this paper, we propose iZone system for safe walking of children. The proposed system recognizes the state that a child is down a roadway as a dangerous situation. And then it informs the surrounding adults and guardians of the child in the event of a dangerous situation. The iZone system consists of the iZone device that attaches to a child's bag or clothing, the iZone app for children, the iZone server, and external beacons. The proposed system uses the ultrasonic sensor of the iZone device and the GPS coordinates and external beacons information by the children's smartphone to determine the dangerous situation. The proposed system uses external beacons to calibrate the GPS coordinates. Moreover, it determines whether the child is down the roadway in sidewalk by measuring the height difference between the roadway and the sidewalk using ultrasonic sensor.

• Journal of the Korean Association of Geographic Information Studies
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• v.15 no.2
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• pp.150-160
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• 2012

The purpose of this study is to examine the relationship between children's walking safety or risk of traffic accident and the physical environments around 20 public elementary schools in Changwon-si, Gyeongsangnam-do. Field surveys were conducted to assess the street-level objective and subjective walking environments. The GIS method was used for measuring the neighborhood-level land use patterns. Children's walking safety and risk of traffic accident data were collected from the 6,381 grade 5 to 6 students attending 18 elementary schools through the questionnaire survey. Correlation analysis showed that walking safety and risk of traffic accident of the elementary students were associated with the number of temporary or permanent obstacles on the sidewalk, traffic safety signs, driveway and street intersections, street lights, and percentage of detached housing area and road area on neighbourhood-level. This research will promote to help with constructing a safe routes to school and walking-friendly healthy community.