• Journal of Auto-vehicle Safety Association
• /
• v.4 no.2
• /
• pp.37-43
• /
• 2012

The purpose of this research is to obtain and analyze dynamic responses from human volunteers for the development of the human-like mechanical or mathematical model for Korean males in automotive rear collisions. This paper focused on the introduction to a low-speed rear impact sled test involving Korean male subjects, and the accumulation of the motion of head and neck. A total of 50 dynamic rear impact sled tests were performed with 50 human volunteers, who are 30-50 year-old males. Each subject can be involved in only one case to prevent any injury in which he was exposed to the impulse that was equivalent to a low-speed rear-end collision of cars at 5-8 km/h for change of velocity, so called, ${\Delta}V$. All subjects were examined by an orthopedist to qualify for the test through the medical check-up of their necks and low backs prior to the test. The impact device is the pendulum type, tuned to simulate the crash pulse of a real vehicle. All motions and impulses were captured and measured by motion capture systems and pressure sensors on the seat. Dynamic responses of head and T1 were analyzed in two cases(5 km/h, 8 km/h) to compare with the results in the previous studies. After the experiments, human subjects were examined to check up any change in the post medical analysis. As a result, there was no change in MRI and no injury reported. Six subjects experienced a minor stiffness on their back for no more than 2 days and got back to normal without any medical treatment.

• Smart Structures and Systems
• /
• v.18 no.6
• /
• pp.1169-1188
• /
• 2016

Real-time substructuring techniques are currently an advanced experimental method for testing large size specimens in the laboratory. In dynamic substructuring, the whole tested system is split into two linked parts, the part of particular interest or nonlinearity, which is tested physically, and the remanding part which is tested numerically. To achieve near-perfect synchronization of the interface response between the physical specimen and the numerical model, a good controller is needed to compensate for transfer system dynamics, nonlinearities, uncertainties and time-varying parameters within the physical substructures. This paper presents the substructuring approach and control performance of the linear and the adaptive controllers for testing the dynamic characteristics of soil-structure-interaction system (SSI). This is difficult to emulate as an entire system in the laboratory because of the size and power supply limitations of the experimental facilities. A modified linear substructuring controller (MLSC) is proposed to replace the linear substructuring controller (LSC).The MLSC doesn't require the accurate mathematical model of the physical structure that is required by the LSC. The effects of parameter identification errors of physical structure and the shaking table on the control performance of the MLSC are analysed. An adaptive controller was designed to compensate for the errors from the simplification of the physical model in the MLSC, and from parameter identification errors. Comparative simulation and experimental tests were then performed to evaluate the performance of the MLSC and the adaptive controller.

• Journal of the Korean Society for Railway
• /
• v.19 no.6
• /
• pp.777-784
• /
• 2016

In this study, regulation of the performance test load of a vibration-proof fastening system used in urban railways was established through evaluation of the loads that it bears in the field. In order to investigate the range of the dynamic stiffness of the vibration-proof fastening system, dynamic stiffness tests were carried out for three types of vibration-proof fastening system that can be domestically supplied. Train and track interaction analyses in the frequency domain were carried out to evaluate the dynamic wheel loads. The track irregularity, which is a very important input factor in train and track interaction analysis, was considered as a PSD (Power Spectral Density) function, which was derived based on the measured data. The loads on the vibration-proof rail fastening system were evaluated considering various operating conditions in the urban railway. Regulation of the performance test load of the vibration-proof rail fastening system was established based on the evaluated loads.

• Journal of the Korean GEO-environmental Society
• /
• v.11 no.4
• /
• pp.51-59
• /
• 2010

This article is a case study for the example of the foundation design, in the project area of the silty sand layer that is spread shallowly with loose status, to make the site for a structure and build it up. The site is located on the dredged and reclaimed land in Gun-San and In-Cheon that is formed the silty sand layer with loose status range around 10 meters underground level, the solid ground for the lower pile is shown around 20 meters underground level. Therefore, this area has to be done by ground improvement when applying for the shallow method of foundation. Dynamic compaction method considering the conditions of the design loads in each zone has to be decided through comparative review on the method of foundations and pilot field test was conducted, and drilling investigation and plate bearing test were achieved as well. The analysis results of the tests prove that stability against bearing capacity was acquired by ground improvement effect.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.22 no.3
• /
• pp.388-393
• /
• 2013

Carbon fiber reinforced plastic (CFRP) has many desirable qualities, including being lightweight and very strong. These characteristics have led to its use in applications ranging from small consumer products to vehicles. Circular and square CFRP members were fabricated using 8ply unidirectional prepreg sheets stacked at different angles ($[+15^{\circ}/-15^{\circ}]_4$, $[+45^{\circ}/-45^{\circ}]_4$ and $[90]_8$, where $0^{\circ}$ coincides with the axis of the member). Based on the collapse characteristics of a CFRP circular member, the collapse characteristics and energy absorption capability were analyzed. Impact collapse tests were carried out for each section member. In this study, the impact energies at crossheads speeds of 5.52 m/s, 5.14 m/s and 4.57 m/s were 611.52 J, 529.2 J and 419.44 J (circular member) 2.16 m/s, 1.85 m/s and 1.67 m/s are 372.4 J, 274.4 J and 223.44 J (square member). The purpose is to experimentally examine the absorption behavior and evaluation the strength in relation to changes in the stacking configuration when the CFRP circular members with different stacking configurations were exposed to various impact velocities. In addition, the dynamic characteristics were considered.

• Journal of the Korean Society of Physical Medicine
• /
• v.15 no.1
• /
• pp.65-76
• /
• 2020

PURPOSE: The purpose of this study were to determine an intervention that involves proprioceptive exercises combined with cognitive task completion for adults with chronic ankle instability and to investigate the effects of the exercises on the static balance, dynamic balance, and ankle function of such individuals. METHODS: A total of 30 adults suffering from the aforementioned condition were randomly divided into experimental (n=15) and control (n=15) groups. The experimental group performed proprioceptive exercises in combination with cognitive tasks for 15 minutes in each session that was held three times a week for four 4 weeks, whereas the control group carried out only proprioceptive exercises. A Wii Balance Board, which enables examining the fluctuation area distance, and speed, was used to determine static balance; a Y-balance test kit was employed to measure dynamic balance; and the side hop, figure-of-8 hop, and square hop tests were conducted to ascertain ankle function. RESULTS: The results showed that the static balance, dynamic balance, and ankle function of both the experimental and control groups significantly improved. The participants were instructed to perform one-leg postural exercises with and without vision blocking for the affected leg. The experimental group showed more significant improvement than did the controls in terms of the fluctuation distance, speed, and area of static balance. CONCLUSION: In conclusion, although combined proprioceptive exercises and cognitive tasks were insufficient to enhance all types of balance among the subjects, it effectively reinforced their static balance.

• Journal of the Korean Geotechnical Society
• /
• v.27 no.2
• /
• pp.81-90
• /
• 2011

Domestic usage of high strength steel for pile has been limited to steel with yield strength (YS) of 490 MPa. However, design and construction cases abroad show beneficial usage of steel pipe with YS ranging in 500~700 MPa. In this study, YS 590 MPa steel pipe has been tested for driven pile foundation in Songdo area. Pile dynamic analysis (PDA) was carried out for 18 piles of which 16 piles have been reviewed for comparison of the PDA test results with those of GRLWeap analysis using SPT N value. Back analysis of PDA analysis was also carried out to narrow the deviation of standard SPT N value used in GRLWeap analysis. A regression equation is suggested for the shaft and toe resistance according to SPT N values for future GRLWeap analysis that can be used in the designing stage at Songdo area.

• Journal of the Korean Geotechnical Society
• /
• v.17 no.6
• /
• pp.69-83
• /
• 2001

In order to make use of finished municipal landfill as a construction site, it is necessary to consider environmental and geotechnical aspects for the ground improvement and application of waste landfill. In environmental aspect, methods for management of landfill gas and leachate have to be established, and in geotechnical aspect, it is necessary to investigate available method for constructing structure foundation. In this study, the finished landfill was selected for pilot test. Investigation about the environmental characteristics of the waste landfill was performed to establish the methods far management of landfill gas according to monitoring the gas quantity and to investigate economical efficiency according to utilizing landfill gas. Investigation about cases of utilizing the waste landfill in Korea and abroad as construction site was performed and pilot tests were performed to analyze the improvement effects of methods such as dynamic compaction method and PG pile method available to waste landfill. The results of this study showed that economical profits could be gained by utilizing landfill gas and improved waste landfill, besides, dynamic compaction method was effective in case of improvement depth being shallow, and PG pile method was effective in case of improvement depth being deep.

• Journal of the Korean Geotechnical Society
• /
• v.18 no.1
• /
• pp.141-152
• /
• 2002

Although a number of constitutive models have been proposed to define the behavior of geotechnical materials including elastic, plastic, and dynamic response, flew numerical models have been developed for the cyclic shear behavior of rock joints or interfaces. Such realistic constitutive models play an important role in analyzing and predicting the response of joints under dynamic loads. The purpose of this research is to verify the constitutive model modified for rough granite joints based on Disturbed State Concept(DSC) model, which has been successfully verified with respect to other materials such as dry sand-steel interface and wet sand-concrete interface. Furthermore, DSC model is compared and verified with respect to cyclic shear tests and numerical analysis results based on Plesha model. Based on the results of this research, it can be stated that DSC model is capable of characterizing the cyclic shear behavior of rough granite joints under dynamic loads.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.12 no.4
• /
• pp.71-79
• /
• 1992

In general, the accelerogram of earthquake ground motion or the accelerogram obtained from dynamic tests contain various errors. In these errors of the accelerograms, there are instrumental errors(magnitude and phase distortion) due to the response characteristics of accelerometer and the digitizing error concentrated in low and high frequency components and random errors. Then, these errors may be detrimental to the results of data processing and dynamic analysis. An efficient method which can correct the errors of the accelerogram is proposed in this study. The correction of errors can be accomplished through four steps as followes ; 1) using an interpolation method a data form appropriate to the error correction is prepared, 2) low and high frequency errors of the accelerogram are removed by band-pass filter between prescribed frequency limits, 3) instrumental errors are corrected using dynamic equilibrium equation of the accelerometer, 4) velocity and displacement are obtained by integrating corrected accelerogram. Presently, infinite impulse response(IIR) filter and finite impulse response (FIR) filter are generally used as band-pass filter. In the proposed error correction procedure, the deficiencies of FIR filter and IIR filter are reduced and, using the properties of the differentiation and the integration of Fourier transform, the accuracy of instrument correction and integration is improved.