• Journal of Korea Entertainment Industry Association
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• v.15 no.8
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• pp.363-377
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• 2021

The present study investigated the effects of dynamic tubing gait training(I and II) on the postural alignment, gait, and quality of life in chronic patients with Parkinson's disease. This study is based on the case study that recruited a total of 3 patients with chronic Parkinson's disease (Hoehn and Yahr Stage of 1 to 3 each one person). Dynamic tubing gait training (I and II) applied to chronic patients with Parkinson's disease for 25 sessions, 30 minutes a day, 5 days a week, over 5 weeks period. To investigate the effects of this study, evaluating using the postural alignment test, muscle activity tests, gait analysis, and quality of life scale for patient with Parkinson's disease. After the intervention of Dynamic tubing gait training (I and II), Trunk flexion was decreased. Also, during walking from initial contact (IC) to mid stance (Mst), muscle activity of Quadriceps, Hamstring, and Tibialis Anterior (TA) was increased and muscle activity of Gastrocnemius was decreased. The muscle activation of Erector Spinae (ES T12, L3) was increased in the H&Y I and III stages and decreased in the H&Y II stage. Length of gait line, single support line, ant/post position and lateral symmetry of center of pressure (COP) parameters improved. The spatio-temporal gait parameters including of step length, stride length, and velocity was increased, and cadence decreased. Further the quality of life of patients with Parkinson's disease was improved. Based on these findings, Dynamic tubing gait training (I and II) could be applied as a new approach to improve posture, gait, quality of life in chronic patients with Parkinson's disease for more than 5 years, whose drug resistance is halved.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3D
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• pp.425-433
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• 2006

The presented work provided a predictive equation for dynamic modulus of hot mix asphalt, which showed higher reliability and more simplicity. Lots of test result by UTM at laboratory has been used to develop the precise predictive equation. Evaluation of dynamic modulus for 13mm and 19mm surface course and 25mm of base course of hot mix asphalt with granite aggregate and two asphalt binders (AP-3 and AP-5) were carried out. Superpave Level 1 Mix Design with gyrator compactor was adopted to determine the optimum asphalt binder content (OAC) and the measured ranges of OAC were between 5.1% and 5.4% for surface HMA, and around 4.2% for base HMA. The dynamic modulus and phase angle were determined by testing on UTM, with 5 different testing temperature (-10, 5, 20, 40, & $55^{\circ}C$) and 5 different loading frequencies (0.05, 0.1, 1, 10, 25 Hz). Using the measured dynamic modulus and phase angle, the input parameters of Sigmoidal function equation to represent the master curve were determined and these will be adopted in FEM analysis for asphalt pavements. The effect of each parameter for equation has been compared. Due to the limitation of laboratory tests, the reliability of predictive equation for dynamic modulus is around 80%.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.707-717
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• 2006

As an alternative to conventional prestressed concrete (PSC) girders, various types of PSC girders are either under development or have already been applied in bridge structures. Incrementally prestressed concrete girder is one of these newly developed girders. According to the design concept, these new types of PSC girders have the advantages of requiring less self-weight while having the capability of longer spans. However, the dynamic interaction between bridge superstructures and passing trains is one of the critical issues concerning these railway bridges designed with more flexibility. Therefore, it is very important to evaluate modal parameters of newly designed bridges before doing dynamic analyses. In the present paper, a 25 meters long full scale PSC girder was fabricated as a test specimen and modal testing was carried out to evaluate modal parameters including natural frequencies and modal damping ratios at every prestressing stage. During the modal testing, a digitally controlled vibration exciter as well as an impact hammer is applied, in order to obtain precise frequency response functions and the modal parameters are evaluated varying with construction stages. Prestressed force effects on changes of modal parameters are analyzed at every incremental prestressing stage. With the application of reliable properties from modal experiments, estimation of dynamic performances of PSC girder railway bridges can be obtained from various parametric studies on dynamic behavior under the passage of moving train. Dynamic displacements, impact factor, acceleration of the slab, end rotation of the girder, and other important dynamic performance parameters are checked with various speeds of the train.

• Journal of the Korean GEO-environmental Society
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• v.18 no.7
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• pp.37-47
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• 2017

In this study, a series of full-scale field tests on prebored and precast steel pipe piles and the corresponding numerical analysis have been conducted in order to study the characteristics of pile load-settlement relations and shear stress transfer at the pile-soil interface. Dynamic pile load tests (EOID and restrike) have been performed on the piles and the estimated design pile loads from EOID and restrike tests were analysed. Class-A type numerical analyses conducted prior to the pile loading tests were 56~105%, 65~121% and 38~142% respectively of those obtained from static load tests. In addition, design loads estimated from the restrike tests indicate increases of 12~60% compared to those estimated in the EOID tests. The EOID tests show large end bearing capacity while the restrike tests demonstrate increased skin friction. When impact energy is insufficient during the restrike tests, the end bearing capacity may be underestimated. It has been found that total pile capacity would be reasonably estimated if skin friction from the restrike tests and end bearing capacity from the EOID are combined. The load-settlement relation measured from the static pile load tests and estimated from the numerical modelling is in general agreement until yielding occurs, after which results from the numerical analyses substantially deviated away from those obtained from the static load tests. The measured pile behaviour from the static load tests shows somewhat similar behaviour of perfectly-elastic plastic materials after yielding with a small increase in the pile load, while the numerical analyses demonstrates a gradual increase in the pile load associated with strain hardening approaching ultimate pile load. It has been discussed that the load-settlement relation mainly depends upon the stiffness of the ground, whilst the shear transfer mechanism depends on shear strength parameters.

• The Korean Journal of Nuclear Medicine Technology
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• v.20 no.1
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• pp.59-65
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• 2016

Purpose Dynamic kidney scan is a typical imaging technique that visualizes kidney function. Reproducibility of dynamic kidney scans has been evaluated by comparing low-dose kidney scans with low-dose radiopharmaceutical and standard dynamic kidney scan. With this comparative study, if reproducibility is superb, the dynamic kidney scan method with reduced radioactivity to patients is to be utilized and radiation exposure to patient is to be reduced. Materials and Methods For gamma camera, Orbiter, SymbiaE (Siemens, Germany) was used. Among patients who had used 370 Mbq (10 mCi) from January of 2013 to February 2014 and other patients who had used 185 Mbq (5 mCi) from March of 2014 to July of 2015 with identical condition, 21 subjects using DTPA and 20 subjects using $MAG_3$, 41 subjects in total, had been selected as subjects for data. From renogram of the result image, frame of the peak point was selected. Then, region of interest of kidney and background had been selected and Kidney to Background Ratio has been calculated for comparison. Results In tests using DTPA, kidney to background ratio when using 370 Mbq was $5.67{\pm}0.8$ at average while it was $5.62{\pm}0.87$ when using 185 Mbq, which didn't show much difference. Also in the tests using $MAG_3$, kidney to background ratio when using 370 Mbq was $14.95{\pm}2.58$ at average and $14.56{\pm}2.02$ in 185 Mbq, which neither showed much difference. In paired sample t-test, p-value was 0.566 in DTPA and 0.363 in $MAG_3$, which confirmed that there was no difference between the groups. Conclusion In identical patients, when dose was decreased from 370 Mbq to 185 Mbq, reproducibility of dynamic kidney scan was proven to be excellent. Low-dose Dynamic kidney scan can achieve results with fine reproducibility without improvement in performance of gamma camera and is expected to reduce radiation exposure to patient.

• Geomechanics and Engineering
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• v.10 no.4
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• pp.455-470
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• 2016

In ballasted railway tracks, ballast fouling due to finer material intrusion has been identified as a challenging issue in track maintenance works. In this research, deformation characteristics of crushed stone-sand mixtures, simulating fresh and fouled ballasts were studied from laboratory and a 3-D discrete element method (DEM) triaxial compression tests. The DEM simulation was performed using a recently developed DEM approach, named, Yet Another Dynamic Engine (YADE). First, void ratio characteristics of crushed stone-sand mixtures were studied. Then, triaxial compression tests were conducted on specimens with 80 and 50% of relative densities simulating dense and loose states respectively. Initial DEM simulations were conducted using sphere particles. As stress-strain behaviour of crushed stone-sand mixtures evaluated by sphere particles were different from laboratory specimens, in next DEM simulations, the particles were modeled by a clump particle. The clump shape was selected using shape indexes of the actual particles evaluated by an image analysis. It was observed that the packing behaviour of laboratory crushed stone-sand mixtures were matched well with the DEM simulation with clump particles. The results also showed that the strength properties of crushed stone deteriorate when they are mixed by 30% or more of sand, specially under dense state. The results also showed that clump particles give closer stress-strain behaviour to laboratory specimens than sphere particles.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.12
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• pp.1296-1303
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• 2012

There is a certain limit to reproduce phenomena between the real vehicle and road, since the existing methods to verify durability of the wheel are mostly uni-axial tests. And the change of durability of the wheel can't be predicted since these tests don't consider the camber angle and lateral force as important factors. In this paper, the FE models of the wheel-tire and drum are created. Then, the vertical and lateral loads are applied to wheel-tire assembly and the camber angle is applied by inclining the wheel-tire assembly to the drum. Based on the analysis result, the crack position is predicted to be created in the body of the wheel. The variation of the stress according to the camber angle is verified and the maximum spot of the stress changes continually.

• Wind and Structures
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• v.10 no.6
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• pp.555-576
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• 2007

Statistical analysis on the measured responses of a suspension bridge deck (Law, et al. 2007) show that vibration response at the first torsional mode of the structure has a significant increase at and beyond the critical wind speed for vortex shedding as noted in the wind tunnel tests on a sectional model. This paper further analyzes the measured responses of the structure when under typhoon conditions for any possible vortex shedding events. Parameters related to the lifting force in such a possible event and the vibration amplitudes are estimated with a single-degree-of-freedom model of the system. The spatial correlation of vortex shedding along the bridge span is also investigated. Possible vortex shedding events are found at both the first torsional and second vertical modes with the root-mean-square amplitudes comparable to those predicted from wind tunnel tests. Small negative stiffness due to wind effects is observed in isolated events that last for a short duration, but the aerodynamic damping exhibits either positive or negative values when the vertical angle of wind incidence is beyond ${\pm}10^{\circ}$. Vibration of the bridge deck is highly correlated in the events at least in the middle one-third of the main span.

• Carbon letters
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• v.22
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• pp.36-41
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• 2017

Biodegradable epoxy (B-epoxy) was prepared from diglycidyl ether of bisphenol A and epoxidized linseed oil. The mechanical properties of B-epoxy composites reinforced with multi-walled carbon nanotubes (MWCNTs/B-epoxy) were examined by employing dynamic mechanical analysis, critical stress intensity factor ($K_{IC}$) tests, and impact strength tests. The electromagnetic interference shielding effectiveness (EMI-SE) of the composites was evaluated using reflection and absorption methods. Mechanical properties of MWCNTs/B-epoxy were enhanced with an increase in the MWCNT content, whereas they deteriorated when the MWCNT content was >5 parts per hundred resin (phr). This can likely be attributed to the entanglement of MWCNTs with each other in the B-epoxy due to the presence of an excess amount of MWCNTs. The highest EMI-SE obtained was ~16 dB for the MWCNTs/B-epoxy composites with a MWCNT content of 13 phr at 1.4 GHz. The composites (13 phr) exhibited the minimum EMI-SE (90%) when used as shielding materials at 1.4 GHz. The EMI-SE of the MWCNTs/B-epoxy also increased with an increase in the MWCNT content, which is a key factor affecting the EMI-SE.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.3
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• pp.348-359
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• 2018

A series of indoor simulation tests on a large-sized shaking table was performed, which was used to simulate the earthquake ground motion for the pipe-soil interaction system to be tested. The purpose of this study is to examine the dynamic characteristic and seismic response of a length of PVC pipeline lay on a clay seabed under seismic load. The pipeline was fully instrumented to provide strain and acceleration responses in both transverse and in-line. Dynamical modal tests show that corresponding mode shapes vertically and horizontally are basically the same. But the absolute values of the natural frequencies vertically are all higher than those corresponding values in transverse. It turned out that the geometry configuration of riser affects its stiffness. Seismic response of pipeline depends significantly on the waveform, and Peak Ground Acceleration (PGA). As the seismic loading progressed, the strain response was severe around both TDZ and catenary zone. Additionally, strain responses in top and bottom positions were more severe than the result in left or right side of the pipeline in the same section.