• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.335-341
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• 1998

In this study, the dynamic characteritics in various loading methods for wear tester were investigated experimentally. As for the dead-weight, the pneumatic, and the hydraulic method, the load control performance against external disturbances was estimated under the several loading conditions like the different sliding speed, the varied normal load, and the misaligument. The hydraulic loading method showed the most stable loading performance of all the loading methods in the experiment.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.779-782
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• 1999

This study was carried out to estimate the effects of the loading conditions on the corrosion of reinforcing bars and permeation of chloride ion. The permeation of chlorides depends not only on the transfer properties in concrete but also on the load applied in the case of reinforced concrete structures. Recent studies reported that the loading conditions affected the corrosion rate of the reinforcing bars under existence of an external current supply. But it was not reported that loading conditions affected corrosion of reinforcing bar caused by the characteristics of permeation and the process of cracking. In this experiment, it was shown that the corrosion of reinforcing bars and the characteristics of permeating were greatly affected by the loading conditions.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1992.10a
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• pp.127-132
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• 1992

The effect of 5 typical rise ratio(h/a=2/9, 5/18, l/3, l/2, 2/3) on the buckling characteristics of single-layer latticed domes with rectangular network under the external pressure are the theoretically studied on the basis of geometically nonlinear FEM and shell analogy method. The loading conditions are 4 types, that is, 1) the uniform pressure loading 2)the uniform snow loading 3) the half - sided asymmetric pressure loading 4) the half - sided asymmetric snow loading.

• Physical Therapy Korea
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• v.5 no.3
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• pp.1-10
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• 1998

In motor learning, the relative frequency of external feedback is the proportion of external feedback presentations divided by the total number of practice trials. In earlier studies, increasing the percentage of body weight loading on the affected leg of hemiplegic patients, external feedback was continuously produced as the patient attempted to perform a movement. This feedback was produced to enhance the learning effect. However, recent studies in nondisabled populations have suggested that compared with 100% relative frequency conditions, practice with lower relative frequencies is more effective. My study compared the effect of 100% relative frequency conditions with 67% relative frequency conditions to determine what effect they exerted on motor learning for increasing the percentage of body weight loading on the affected lower limbs of patients with hemiplegia. Twenty-four hemiplegic patients were randomly assigned to one of two experimental groups. Each group practiced weight transfer motor learning on a machine. During practice, visual feedback was offered to all subjects. The experiment was carried out with full visual feedback for patients in group one but only 67% visual feedback for patients in group two. The percentage of loading on the affected leg was recorded four times: before learning (baseline value), immediately after learning, 30 minutes after learning, 24 hours after learning. The results were as follows: 1. In the 100% visual feedback group, the percentage of loading on the affected leg increased significantly in all three testing modes over the baseline value. 2. In the 67% visual feedback group, the percentage of loading on the affected leg increased significantly in all three measurements. 3. Immediately after learning, the learning effect was not significantly different between the two groups, but was significantly greater after both the 30 minutes delay and the 24 hours period. These results suggest that the 33% reduction in the provision of visual feedback may enhance the learning effect of increasing the percentage of body weight loading on the affected leg in patients with hemiplegia.

• Journal of the Korean GEO-environmental Society
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• v.9 no.6
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• pp.71-79
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• 2008

The underground conduit laid under different environments exhibits various behaviour according to the ground and external load as well as the loading time and conditions, so on. As the environmental conditions are usually different even within the same area, it is very difficult to correctly predict the stress conditions and behaviour of the underground conduit using currently available theoretical analysis. Especially, it is not yet satisfied in Korea for the evaluation of the underground conduit under the influence of the load of vehicles or unexpected loading conditions. Thus, in this study the assessment for the excavation depth and ground disturbance was carried out with a large box model test and numerical analysis. Numerical analysis was also performed for the assessment of dynamic loading conditions like railway load.

• Computers and Concrete
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• v.18 no.6
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• pp.1097-1112
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• 2016

Fire loading causes a critical collapse of RC (Reinforced Concrete) Structures since the embedded steels inside are relative week against high elevated temperature. Several numerical frameworks for fire resistance have been proposed, however they have limitations such as unstable convergence and long calculation period. In the work, 2-D nonlinear FE technique is proposed using Galerkin method for RC structures under fire loading. Closed-form element stiffness with a triangular element is adopted and verified with fire test on three RC slabs with different fire loading conditions. Several simulations are also performed considering fire loading conditions, water contents, and cover depth. The proposed numerical technique can handle time-dependent fire loading, convection, radiation, and material properties. The proposed technique can be improved through early-aged concrete behavior like moisture transport which varies with external temperature.

• KCI Concrete Journal
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• v.12 no.1
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• pp.69-77
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• 2000

The reinforced concrete(RC) flexural members strengthened with steel plate/CFS at soffit have initial stresses and strains in reinforcements and concrete caused by the service loads at the time of retrofitting works. These initial residual stresses and strains of strengthened beams may affect the flexural performance of the rehabilitated beams. The objective of this study is to evaluate and verify the effectiveness of rehabilitation by external bonded steel plates and CFS to the tension face of the beams under three conditions of pre-loading. Thirteen beam specimens are tested and analyzed. Main test parameters are pre-loading conditions, strengthening materials and reinforcement ratio of specimens. The effect of test parameters on the strengthened beams is analyzed from the maximum load capacity, load-deflection relationship, state of stress of the materials. crack propagation phase, and failure modes. Both test results and design formulas of ACI Code provisions are compared and evaluated.

• Journal of Korean Society on Water Environment
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• v.31 no.5
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• pp.556-562
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• 2015

In order to remove the organic substances and the nitrate-nitrogen contained in wastewater, some researchers have studied the simultaneous removal of organics and nitrogen by using different biocathode microbial fuel cells (MFCs). The operating conditions for removing the contaminants in the MFCs are the external resistances, HRTs, the concentration of the influent wastewater, and other factors. This study aimed to determine the effect of the external resistors and organic loading rates, from the changing HRT, on the removal of the organics and nitrogen and on the production of electric power using the Denitrification Biocathode - Microbial Fuel Cell (DNB-MFC). As regards the results of the study, the removal efficiencies of $SCOD_{Cr}$ did not show any difference, but the nitrate-nitrogen removal efficiencies were increased by decreasing the external resistance. The maximum denitrification rate achieved was $129.2{\pm}13.54g\;NO_3{^-}-N/m^3/d$ in the external resistance $1{\Omega}$, and the maximum power density was $3,279mW/m^3$ in $10{\Omega}$. When the DNB-MFC was operated with increasing influent organic and nitrate loading by reducing the HRTs, the $NO_3{^-}-N$ removal efficiencies were increased linearly, and the maximum nitrate removal rate was $1,586g\;NO^3{^-}-N/m^3/d$ at HRT 0.6 h.

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.558-565
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• 1999

Rubber wheel-type AGT has two major kinds of bogie; one is the bogie type and the other and passenger loads. This paper deals with the statics analysis for two types of bogie frame subjected to combined external forces, as well as independent ones specified in UIC 515-4. Furthermore, the dynamics analysis is performed under vibrational loading conditions so as to compare dynamic characteristics, Numerical results by using commercial packages, Ⅰ-DEAS and NASTRAN show that maximum stresses do not exceed the yielding level of material used for both bogies. From an overall viewpoint of strength, the bogie type turns out to be superior to the steering type except the case of a lateral loading. It is also observed that the steering type shows a be stiffened. It is strongly anticipated that vibrational fatigue analysis should be carried out under realistic loading conditions closely matching to situations such as running surface and lateral clearances along the guideway.

• Geomechanics and Engineering
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• v.16 no.2
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• pp.113-124
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• 2018

Under repeated loading, the residual stresses within the subgrade and subsoil can accelerate the deformation of the road structures. In this paper, a series of laboratory cyclic loading model tests and small-scale model tests were conducted to investigate the dynamic stress response within soils under different loading conditions. The experimental results showed that a dynamic stress accumulation effect occurred if the soil showed cumulative deformation: (1) the residual stress increased and accumulated with an increasing number of loading cycles, and (2) the residual stress was superimposed on the stress response of the subsequent loading cycles, inducing a greater peak stress response. There are two conditions that must be met for the dynamic stress accumulation effect to occur. A threshold state exists only if the external load exceeds the cyclic threshold stress. Then, the stress accumulation effect occurs. A higher loading frequency results in a higher rate of increase for the residual stress. In addition to the superposition of the increasing residual stress, soil densification might contribute to the increasing peak stress during cyclic loading. An increase in soil stiffness and a decrease in dissipative energy induce a greater stress transmission within the material.