• Journal of the Korean Geotechnical Society
• /
• v.32 no.1
• /
• pp.5-18
• /
• 2016

In this study, we grasped the resistance state of the back ground which had a notable influence on computing the lateral resistance of the laterally loaded pile group in the homogeneous ground by the model test. Resistance state was grasped as the depth of rotation-point, wedge failure angle, and wedge wing angle. The model experiment is performed by varying the width, spacing and number of piles and the relative density of sand in this study. According to the observation of the rear ground surface deformation of the piles in lateral load, rotation point ratio, wedge failure angle, and wedge wing angle of the front row were similar to those of the middle row; however, those of the back row were relatively smaller. The rotation point ratio, wedge failure angle and wedge wing angle of the piles in parallel were the same as those of a single pile. Based on the model test results, equations for estimation of the rotation-point, wedge failure angle, and wedge wing angle are proposed.

• Physical Therapy Rehabilitation Science
• /
• v.12 no.1
• /
• pp.1-11
• /
• 2023

Objective: This study aimed to investigate the effects of squat posture, band position, and contraction type on the muscle activity of the hip abductors during resisted lateral band walking. Design: A cross-sectional survey study Methods: 24 healthy male subjects were recruited, and surface electromyography was used to measure the muscle activity of the gluteus maximus, gluteus medius, and tensor fascia lata of the dominant leg during lateral walking exercises. Resistance bands were applied to the knees, ankles, and feet in semi-squat and squat postures, and exercises were randomly performed under six different conditions. Results: The results showed significant differences in muscle activity in the gluteus maximus, gluteus medius, and tensor fascia lata according to posture, band position, and contraction type (p<0.05). The muscle activity of the hip abductors increased in the squat posture and with the band placed on the distal joint compared to the proximal joint (p<0.05). Additionally, muscle activity was higher in the eccentric contraction phase than in the concentric contraction phase (p<0.05). Contrary to previous studies, moving the resistance band from the ankle to the foot increased the muscle activity of the tensor fascia lata while the activity of the gluteus maximus and gluteus medius also increased. Conclusions: According to the results, squat posture with a resistance band placed on the feet and using an eccentric contraction phase were found to be the most effective methods for strengthening the hip abductors.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.41 no.3
• /
• pp.267-273
• /
• 1992

An advanced on-resistance model of VDMOS devices in the low voltage regimes is proposed and verified by 2-D device simulations. The model considers the lateral gaussian doping profiles in the channel region and exact current spreading angles in the epitaxial layer for both linear and cellular geometries by employing the conformal mapping, It is found out that the on-resistance of low voltage VDMOS may be overestimated considerably if it is analyzed by the conventional method. The 2-D device simulation results show that the proposed model is valid for the VDMOS devices in the low voltage regimes.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.10a
• /
• pp.1090-1097
• /
• 2008

This study conducted the decision method of lateral flow in abutment structures founded on the soft soils and the reliability analysis on the foundation pile for abutment. On the basis of the results, this study proposed the reliability design model. Reliability analysis was conducted by applying second moment method, point estimation method, and expected total cost minimization to lateral movement index, lateral movement decision index, modified lateral movement decision index, and circular failure safety factor for the decision criteria of lateral flow. The reliability index by analysis method had a similar tendency each other. Point estimation method was found as a practical method in the aspect of convenience because it could conduct the analysis only by mean and standard deviation as well as the partial derivative on random variables was not necessary. Optimum reliability index and optimum safety according to increasing in failure factors and load ratio were analyzed and loads and resistance factors of the design criteria of optimum reliability were estimated. It presented rational design model which can consider construction level and stability and economical efficiency overall.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.12
• /
• pp.1305-1310
• /
• 2005

As a way to the optimum design of the collector well lateral in riverbed filtration, experiments were performed using sand tanks which were connected to form a model lateral system. Measured were the residual hydraulic heads along the laterals, the discharge rates at each sand tank and the production rates at the collector well while the model laterals were operated with various scenarios of changing parameters including water level of the collector well, the lateral diameter and length, and the hydraulic conductivity of the sand. Results showed that riverbed filtration could be more efficient when the resistance in the lateral was weak compared with the resistance in the sand, which was indicated by the more flattened distribution of the residual hydraulic heads along the lateral. Results also showed that the discharge rate increased exponentially with the approach to the collector well, and that the exponent increased as the lateral diameter decreased and/or the hydraulic conductivity of the sand increased. It was also seen that the well production increased with the increase in the lateral length and diameter although the marginal productivity decreased. It could be concluded that the axial flow velocity in the lateral was an important factor governing the efficiency of a lateral in riverbed filtration and that the maximum entrance velocity to the collector well, over which the efficiency decreased drastically, was about 1 m/sec under the conditions of this study.

• Steel and Composite Structures
• /
• v.37 no.3
• /
• pp.273-289
• /
• 2020

Due to the unique construction method of modular steel buildings (MSBs) with units prefabricated fully off the site and assembled quickly on the site, the inter-module connection for easy operation and overall performance of the system were key issues. However, it was a lack of relevant research on the system-level performance of MSBs. This study investigated the seismic performance of two-storey modular steel structure with a proposed vertical rotary inter-module connection. Three full-scale quasi-static tests, with and without corrugated steel plate and its combination, were carried out to evaluate and compare their seismic behaviour. The hysteretic performance, skeleton curves, ductile performance, stiffness degradation, energy dissipation capacity, and deformation pattern were clarified. The results showed that good ductility and plastic deformation ability of such modular steel structures. Two lateral-force resistance mechanisms with different layout combinations were also discussed in detail. The corrugated steel plate could significantly improve the lateral stiffness and bearing capacity of the modular steel structure. The cooperative working mechanism of modules and inter-module connections was further analyzed. When the lateral stiffness of upper and lower modular structures was close, limited bending moment transfer may be considered for the inter-module connection. While a large lateral stiffness difference existed initially between the upper and lower structures, an obvious gap occurred at the inter-module connection, and this gap may significantly influence the bending moments transferred by the inter-module connections. Meanwhile, several design recommendations of inter-module connections were also given for the application of MSBs.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.5C
• /
• pp.199-206
• /
• 2009

This paper presents full scale model tests on the various types of model piles carried out to estimate the behavior of laterally loaded steel-concrete composite piles. Subgrade-reaction spring system was developed to simulate the reaction of ground in laboratory condition. In addition, lateral behavior of piles under working load condition was estimated using composite loading system, which is available for independent loading in vertical and horizontal direction. Steel-concrete composite piles showed higher efficiency in lateral resistance rather than drilled shaft made of reinforced concrete. The lateral resistance of composite pile was larger than the summation of steel pile and concrete pile due to the composite effect by steel casing. The effect of shear key or strength of concrete on the behavior of composite pile was examined. The substitution of reinforcing bar by steel casing was also investigated.

• Journal of the Korea Concrete Institute
• /
• v.11 no.6
• /
• pp.101-112
• /
• 1999

Structural walls have been mostly used for the design of reinforced concrete buildings in seismic areas because they play a role as an efficient bracing system and offer great potential for lateral load resistance and drift control. The lateral resistance system for the earthquake load should be designed to have enough ductility and stable hysteretic response in the critical regions where plastic deformation occurred beyond yielding. The behavior of the reinforced concrete element to experience large deformation in the critical areas by a major earthquake is affected by the performance of the confined core concrete. Thus, the confinement of concrete by suitable arrangements of transverse reinforcement results in a significant increase in both the strength and ductility of compressed concrete. This paper reports the experimental results of reinforced concrete structural walls for wall-type apartment structure under axial loads and cyclic reversal of lateral loads with different confinement of the boundary elements. The results show that confinement of the boundary element by open 'U'-bar and cross tie is effective. The shear strength capacity is not increased by the confinement but deformation capacity is improve.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.03a
• /
• pp.1087-1094
• /
• 2008

The drilled pier foundation is widely used to support transmission line structures due to its simplicity of construction. When this foundation type is used in conjunction with a single shaft or H-frame structure, it is subjected to a high overturning moment, combined with modest vertical and shear loads. Since the length and diameter of drilled piers are often governed by a maximum permissible deflection, many drilled piers being installed today are very conservatively designed. In this study, Five prototype field-tests (1/8 scale) have been conducted in order to determine the lateral resistance of drilled pier foundation for single pole structures. These test results reveal the test piers behaved essentially as rigid bodies in soil (6D) and the center of rotation of the pier were typically 0.6~0.4 of the pier depth below ground surface. Test results also show the relationship between the applied load and the deflection at the top of the pier is highly nonlinear.

• Geomechanics and Engineering
• /
• v.12 no.3
• /
• pp.505-522
• /
• 2017

A fundamental study of drilled shafts-soil systems subjected to lateral cyclic loading in weathered soil was conducted using numerical analyses. The emphasis was on quantifying the soil resistance of laterally cyclic loaded pile using 3D finite element analysis. The appropriate parametric studies needed for verifying the cyclic p-y characteristic are presented in this paper. A framework for determining the cyclic lateral load transfer curve (p-y curves) on the basis of numerical analyses is proposed. Through comparisons with results of field load tests, the three-dimensional numerical methodology in the present study is in good agreement with the general trend observed by in situ measurements and thus, represents a realistic soil-pile interaction for laterally loaded piles in soil than that of existing p-y method. It can be said that a rigorous present analysis can overcome the limitations of existing cyclic p-y methods to some extent by considering the effect of realistic three-dimensional combination of pile-soil forces. The proposed cyclic p-y curve is shown to be capable of predicting the behavior of the drilled shafts in weathered soil.