• Journal of the Korean Geotechnical Society
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• v.28 no.4
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• pp.5-21
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• 2012

In our country, in the case of traditional design of pile foundations, only a design depending on end bearing has been performed. However, through the load transfer measurement data that have been carried out for in-situ piles, it was known that skin frictional force was mobilized greatly. In this study, through the analysis of the load transfer test cases of driven steel pipe piles and large-diameter drilled shafts, load bearing aspects of pile foundation depending on pile construction methods and pile load test methods were established. The average sharing ratios of skin frictional force were independent of pile types, pile load test methods, relative pile lengths, pile diameters and soil types. Because the average sharing ratios were over 50%, the case pile foundations mostly behaved as a friction pile and the extremely partial case pile foundation behaved as a combined load bearing pile.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.1
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• pp.1-9
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• 2010

Pile reinforcement systems with enlarged upper section are newly introduced by using a mechanism that most of horizontal forces are resisted in the upper part of the pile. The new systems are expected to be effectively applicable to the marine structures including port and harbor facilities. In this study, three different reinforcement methods such as bucket pile type, top base pile type, and grouting reinforcement type were utilized in the 3-D. numerical simulations. The parametric study deals with the effects of various factors including soil types and stratigraphy, reinforcement methods, type and dimension of the pile on the lateral behaviors of the pile. The results show that the reinforcement method with bucket pile is the most efficient one compared to the top base pile type and grouting reinforcement type.

• Journal of the Korean GEO-environmental Society
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• v.2 no.2
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• pp.13-22
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• 2001

In this study, centrifuge model tests were fulfilled to investigate the characteristics of bearing capacity of paper ash as a filling material. The model tests were done varying the footing width and gravity level. The settlement and vertical soil pressure by loading were measured. The results from the tests were compared with the one from FLAC program using finite difference method and bearing capacity theory. After all, it was shown that the characteristics of load-settlement represented the local shear failure, which the settlement ratio s/B showed inflection point around 25~30%. As g-level and footing width were increasing, the load strength was increasing. The ultimate bearing capacity from the tests was very closed the results from Terzaghi's theory. As the distance from footing center was increasing, the vertical soil pressure was decreasing. If E/B is higher than 7, the stress by loading was almost increasing. The vertical displacement from loading was the largest one around under the footing and was almost occurred when the depth>4cm and E/B is higher than 5.0.

• Journal of the Korean GEO-environmental Society
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• v.10 no.6
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• pp.5-18
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• 2009

In construction of buildings in Korea, the buildings are frequently founded on the weathered ground (weathered soil/rock, fractured rock). In this case, to make a full use of a bearing capacity of a weathered ground for economic design, the shallow mat foundation system could be used. In this study, we have researched three cases of mat foundations on the weathered ground in Korea, and analyzed and considered the design procedures and the reinforcing methods. That is, we have considered the detail design, analysis proceedings, the ground settlement evaluation proceedings, the rock face mapping evaluations after excavation and reinforcing methods of the mat foundation on the weathered ground. And large scale plate load tests on the weathered ground supporting the mat foundation were performed and also load bearing capacity and settlement of actual mat foundation, considering the scale effect, were evaluated.

• Journal of the Korean Geosynthetics Society
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• v.12 no.3
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• pp.1-13
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• 2013

This paper presents the results of a laboratory investigation of the porous pavement substructure effect when reinforced with geocell. In order to analyze load carrying capacity of Geocell, a series of 9 reduced-scale laboratory tests was performed, changing the type, thickness, diameter of Geocell. The results of the analyses indicated that the bearing capacity of the reinforced Geocell increases much more than the non-reinforced Geocell and load carrying capacity was considered to be insignificant according to the type of Geocell. It was also found that the most supportive effects appeared as 30 cm in diameter and 1.8mm in thickness.

• Geotechnical Engineering
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• v.8 no.4
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• pp.81-98
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• 1992

Deep excavation increases utility of underground spaces for high buildings. subways etc. To excavate vertically the underground, safe earth retaining walls and supporting systems should be prepared. Recently anchors have been used to support the excavation wall. The anchored excavation has some advantages toprovide working space for underground construction. In this paper the prestressed anchor loads were measured by load cells which attacted to the anchors to support the excavation walls at eight construction fields. where under-ground deep excavation was performed on cohesionless soils. The lateral pressures on the retaining walls, which are estimated from the measured anchor forces, shows a trapezoidal distribution that the pressure increases linearly with depth from the ground surface to 30% of the excavation depth and then keeps constant value regardless of the stiffness of the walls. The maximum lateral pressure was same to 63% of the Ranking active earth pressure or 17% of the vertical overburden pressure at the final depth The investigation of the measured lateral pressure on the anchored excavation walls shows that empirical earth pressure diagram presented by Terzaghi-Peck and Tschebotarioff could be applied with some modifications to determine anchor loads for the anchored excavation in cohesionless soils.

• Journal of the Korean Geotechnical Society
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• v.20 no.3
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• pp.85-96
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• 2004

The ultimate bearing capacity of surface foundations on a sand layer overlying clay has been theoretically investigated. First, a review of previous studies on the bearing capacity problems for this type of foundation was performed and a discussion was presented concerning the practical application. Second, the kinematic approach of limit analysis was used to calculate the upper bound of the true ultimate bearing capacity. The kinematic solutions are upper bounds and their accuracy depends primarily on the nature of the assumed failure mechanism. This approach makes it convenient to create design charts, and it is possible to trace the influence of parameters. Third, the commercial finite element program ABAQUS was applied to obtain the ultimate bearing capacity based on the elasto-plastic theory. Results obtained from the kinematic approach were compared with those from the program ABAQUS and the limit equilibrium equations proposed by Yamaguchi, Meyerhof and Okamura et al. Finally, the validities of the results from the kinematic approach, the results from the program ABAQUS and the limit equilibrium equations were examined.

• Geotechnical Engineering
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• v.13 no.4
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• pp.163-176
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• 1997

It has long been recognized that the H-beam steel rib has many shortcomings when used as a steel support in tunneling. One of the major shortcomings is the shotcrete shadow created behind H-beam flange which eventually reduces the load bearing capacity of shotcrete shell. In many European countries, plate girder as the H-beam steel rib has been replaced by lattice girder which has many advantages over the H-beam steel rib. Successful application of the lattice girder as a steel support requires a thorough investigation on the load bearing capacity of the lattice girder. Therefore, laboratory bending and compression tests were conducted on lattice girders with the aim of investigating the load bearing capacity of the lattice girders. The results of tests show that the load bearing capacity of laIn twice girders is higher than that of H-beams, which indicates that the lattice girder can be effectively used as a support in tunneling.

• Journal of the Korean Ceramic Society
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• v.41 no.7
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• pp.548-554
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• 2004

A sol-gel method was applied to coat TiO$_2$ on porous silica prepared using slurry foaming method from silica. from the results of XRD, SEM, and BET, the anatase phase was firstly observed at the coated supports with the heated of 50$0^{\circ}C$. The coated supports with the heated of $700^{\circ}C$ had the maximum anatase peak, and the particle size of coated TiO$_2$ was about 1 ${\mu}{\textrm}{m}$. Bending strength and gas permeability of the porous silica were measured for the feasibility as a catalytic supports. In case of the uncoated porous materials with the strength of 2.4 MPa, the strength increased to 3.9∼4.3 MPa after the coating process regardless of the heating temperature. On the other hand, the permeability of the uncoated porous materials decreased from 770${\times}$10$^{-13}$ $m^2$ to 363${\times}$10$^{-13}$ $m^2$ after the coating process, and it decreased with the increasing heating temperature.

• Journal of the Korea Society of Computer and Information
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• v.25 no.8
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• pp.137-144
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• 2020

In this paper, we propose the moderating effects of self-efficacy and social support on the relationship between physical therapists' job stress and psychological burnout. Based on the previous studies, this study set up three types of variables: 1) independent variable, 2) moderating variable, 3) dependent variable. Job stress was identified as an independent variable, self-efficacy and social support was identified as a moderating variable and psychological burnout was identified as a dependent variable. To empirically conduct this study, a total of 200 questionnaires were distributed to physical therapists. Consequently, a total of 155 survey responses were collected. The survey results are as follows. First, the result showed a high-level of correlation among job stress, psychological burnout, self-efficacy, and social support. Second, self-efficacy was found to have a moderating effect on the relationship between the physical therapists' job stress and psychological burnout. Third, social support was found to have a moderating effect on the relationship between the art therapists' job stress and psychological burnout.