• Transactions of the Korean Society of Automotive Engineers
• /
• v.9 no.1
• /
• pp.20-27
• /
• 2001

A variable configuration tracked vehicle(VCTV) is developed to reduce turning energy and improve climbing ability for stairs. This mechanism has four track T-type frames. By changing the driving direction, each track T-type frame rotates to minimize the contact area with ground. It also has better performance than other VCTV in energy consumption of turning. Futhermore this mechanism is more stable than other VCTV on the rough terrain. When climbing stairs, each track T-type frame rotates to obtain a front attack angle and keep stability on steep stairs. The design parameters of components of track T-type frames are optimized to enhance the performance of climbing stairs. Performance indices include a stable angle, a climbing ability, a height of the vertical obstacle. In case that the overall length of the mechanism is 0.2m, it is required that the radius of the wheels should be 5mm and the length track contacted with he ground should be 0.09m to climb higher and steeper stairs.

• Proceedings of the KSR Conference
• /
• 2008.11b
• /
• pp.316-320
• /
• 2008

A light rail transit, using a linear induction motor, is generally composed with reaction plates along railroad track and the three phase primary on the vehicle. This linear induction motor is driven to keep clearance between the primary and the secondary of the ground for preventing any contact. Therefore efficiency and power factor is very low. In addition, the reaction plate installed on the ground throughout entire railway is impossible to keep uniform gap and it may cause system deterioration. In this paper, A rotary-type small-scale model of a linear induction motor for various characteristic analysis is designed. Thrust force, normal force and input current of the model by air-gap variation have been analyzed by using a Finite Element Method (FEM). The effects of air-gap variation on system performance have been considered by analysis results.

• Advances in aircraft and spacecraft science
• /
• v.7 no.2
• /
• pp.91-113
• /
• 2020

This paper analyzes the terminal descent phase of a space lander on a surface of a celestial body. A multibody approach is adopted to build the physical model of the lander and the surface. In this work, a legged landing gear system is considered. Opportune modelling of the landing gear crashbox is implemented in order to accurately predict the kinetic energy. To ensure the stability of the lander while impacting the ground and to reduce the contact forces that arise in this maneuver, the multibody model makes use of a co-simulation with a dedicated control system. Two types of control systems are considered; one with only position variables and the other with position and velocity variables. The results demonstrate the good reliability of modern multibody technology to incorporate control algorithms to carry out stability analysis of ground impact of space landers. Moreover, from a comparison between the two control systems adopted, it is shown how the velocity control leads to lower contact forces and fuel consumption.

• Physical Therapy Rehabilitation Science
• /
• v.12 no.2
• /
• pp.130-139
• /
• 2023

Objective: This study aimed to analyze the effects and characteristics of the height of the treatment table on the force and time of ground reaction (GR) and contact hand (CH) generated from the therapist's feet to generate thrust during spinal manipulation (SM). Design: A cross-sectional survey study Methods: Thirty-six healthy subjects were recruited. SM was performed on the ilium using a knee-high table, where the therapist felt it was easy to control the subject's posture and body shape and comfortable to generate force, as well as a relatively high thigh-high table. The force and time generated by the therapist's GR and CH were simultaneously measured through a force plate. Results: As a result, there was a significant difference in peak force and rundown force at the therapist's GR according to the table height (p < 0.05). In the therapist's CH, there was a significant difference between PreMin (preload minimum) force and peak force (p < 0.05), and there was a significant difference between the time from PreMin to peak and the time of the entire section (p < 0.05). Conclusions: As a result, the generation of increased CH force and faster thrust duration were confirmed by mobilizing the reduced GR force of the therapist to generate thrust than the relatively high table on the knee-high table.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.23 no.5
• /
• pp.502-515
• /
• 2020

To identify the dynamic characteristics of the Auto-leveling system applied to the Tractor-Trailer type Transporter for mounting a large scale precision equipment, Dynamics Modeling & Simulation were performed using general Dynamics Analysis Program - RecurDyn(V9R2). The axial load data, transverse load data and pad trace data of leveling actuators were obtained from M&S. And they were analyzed and compared with each other by parameters, i.e. friction coefficients on the ground, landing ram speed of actuators, and direction & quantity of ground slope. It was observed that ground contact friction coefficients affected to transverse load and pad trace; the landing ram speed of actuators to both amplitude of axial & transverse load, and this phenomena was able to explain from the frequency analysis of the axial load data; the direction of ground slope to driving sequence of landing ram of actuators. But the dynamic behaviors on the two-directional slope were very different from them on the one-directional slope and more complex.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.41 no.5
• /
• pp.523-531
• /
• 2021

In general, the foundation refers to a group pile with several single piles connected by an upper structure. However, when a load is applied to pile groups, the range of stress applied to the ground is expanded and overlapped compared with the single pile, so the overall bearing capacity may decrease. This reduction ratio of bearing capacity is referred to as the efficiency of pile groups. Therefore, in this study, the soil composition, the arrangement and spacing of group piles, and the contact characteristics between the ground and piles were set as analysis variables, and the group pile efficiency and individual pile behavior were analyzed. As a result of the analysis, the efficiency of pile groups tends to converge or decrease when the friction coefficients are increased with ground type. Through this, the optimal efficiency of pile groups can be derived. In addition, through the analysis of individual piles, the load ratio of each pile was analyzed when an upper load was applied. In the case of piles located inside group piles, the load was relatively low, and this is considered to have an influence on the internal ground.

• Korean Journal of Applied Biomechanics
• /
• v.17 no.1
• /
• pp.17-27
• /
• 2007

It is essential for gait analysis to know the distance information. The purpose of this study was to investigate the effects of start and finish distance on the gait variable during walking. Six adolescent participated in this study. Start condition was given by six conditions.: walking forward from (1) one step, (2) three steps, (3) five steps, (4) ten steps, (5) one step after standing walk, and (6) three steps after standing walk, before contacting the force plate. Stop condition was given by four conditions. : stop after (1) one step, (2) two steps, (3) three steps, and (4) ten steps, passing force plate. Repeated measured one-way ANOVA was utilized for data analysis, and the significant level was set at .05. The largest change from the difference of gait velocity exists between the variables of ground reaction force. There were no significant differences in spatio-temporal and posture(angle) variables, as well as ground reaction force variables with walking over the three steps. There were significant differences in gait velocity, knee angle at heel contact, vertical impulse and ankle angle at toe off in short distance.

• PNF and Movement
• /
• v.20 no.1
• /
• pp.59-66
• /
• 2022

Purpose: The aim of this research was to verify the relationship between three-dimensional (3D) ground reaction force (GRF) and severity of leg length discrepancy (LLD) while walking at a normal speed. It used a 3D motion analysis system with force platforms in standing workers with LLD. Methods: Subjects comprising 45 standing workers with LLD were selected. Two force platforms were used to acquire 3D GRF data based on a motion analysis system during gait. Vicon Nexus and Visual3D v6 Professional software were used to analyze kinetic GRF data. The subjects were asked to walk on a walkway with 40 infrared reflective markers attached to their lower extremities to collect 3D GRF data. Results: The results indicated the maximal force in the posterior and lateral direction of the long limb occurring in the early stance phase during gait had significant positive correlation with LLD severity (r = 0.664~0.738, p <0.01). In addition, the maximal force medial direction of the long limb occurring in the late stance phase showed a highly positive correlation with the LLD measurement (r = 0.527, p <0.01). Conclusion: Our results indicate that greater measured LLD severity results in more plantar pressure occurring in the foot area during heel contact to loading response of the stance phase and the stance push-off period during gait.

• The Journal of Korea Robotics Society
• /
• v.18 no.3
• /
• pp.285-292
• /
• 2023

Small-scale ground mobile robots can access confined spaces where people or larger robots are unable. As the scale of the robot decreases, the relative size of the environment increases; therefore, maintaining the mobility of the small-scale robot is required. However, small-scale robots have limitations in using a large number of high-performance actuators, powerful computational devices, and a power source. Insects can effectively navigate various terrains in nature with their legged motion. Discrete contact with the ground and the foot enables creatures to traverse irregular surfaces. Inspired by the leg motion of the insect, researchers have developed small-scale robots and they implemented swing and lifting motions of the leg by designing leg linkages that can be adapted to small-scale robots. In this paper, we propose a leg linkage design for insect-inspired small-scale ground mobile robots. To use minimal actuation and reduce the control complexity, we designed a 1-DOF 3-dimensional leg linkage that can generate a proper leg trajectory using one continuous rotational input. We analyzed the kinematics of the proposed leg linkage to investigate the effect of link parameters on the foot trajectory.

• Korean Journal of Applied Biomechanics
• /
• v.16 no.3
• /
• pp.9-18
• /
• 2006

These studies show that I applied to functional insole (a specific S company) for minimizing shocks and sprain people's ankle arising from running. How to an effect on human body which studied a kinematics and kinetics from 10 college students during experiments. This study imposes several conditions by barefoot, normal running shoes and put functional insole shoes ran under average $2.0{\pm}0.24$ meter per second by motion analysis, ground reaction force and electromyography that used to specific A company. First of all, Motion analysis was caused by Achilles tendon angle, Angle of the lower leg, Angle of the knee, Initial sole angle and Barefoot angle. Second, Contact time, Vertical impact force peak timing, Vertical active force and Active force timing, and Maximum loading rate under impulse of first 20 percent and Value of total impulse caused Ground reaction force. Third. The tendon fo Quadriceps femoris, Biceps femoris, Tibialis anterior and gastronemius medials caused. electromyography. 1. Ground reaction force also showed that statically approximates other results from impact peak timing (p.001), Maximum loading rate(p<.001), Maximum loading rate timing (p<.001) and impulse of first 20 percent (p<.001). 2 Electromyography showed that averagely was distinguished from other factors, and did not show about that. Above experiment values known that there was statically difference between Motion analysis and Ground reaction force under absorbing of the functional insole shoes which was not have an effect on our body for kinetics and kinematics.