• Journal of the Korean Geotechnical Society
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• v.32 no.12
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• pp.45-57
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• 2016

The Inclined Earth Retaining Structure (IER) is the structure using an integrated system of both front supports and inclined back supports to increase the stability for excavation. The IER is a structurally stable temporary excavation method using the back supports restraining the lateral displacement of the front supports as stabilizing piles. The back supports connected to the front supports significantly reduce the earth pressure acting on both the front wall and the front supports by distributing it to the back supports in order to increase the structural stability. In this study, mechanical behaviors of IER according to the head connection type using fixed- or hinge-connection were found by performing numerical analysis and laboratory model tests in the sandy ground. The maximum lateral displacement of fixed-connection was 88% of that of hinge-connection in the numerical analysis. The lateral displacement of fixed-connection was 7% of that of hinge-connection in the laboratory model test results. Furthermore, the earth pressure of the fixed-connection was 67% of that of the hinge-connection in the shear-strain analysis results of the model ground.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.343-358
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• 2008

Piles of a bridge pier are connected with a column through a pile cap(footing). Behavior of the pile foundation can be different according to the connection method between piles and the pile cap. This difference causes a change of the design method. Connection methods between pile heads and the pile cap are divided into two groups ; rigid connections and hinge connections. KHBDC(Korea Highway Bridge Design Code) has specified to use rigid connection method for the highway bridge. In the rigid connection method, maximum bending moment of a pile occurs at the pile head and this helps the pile to prevent the excessive displacement. Rigid methods are also good to improve the seismic performance. However some specifications prescribe that conservative results through investigations for both the fixed-head condition and the free-head condition should be reflected in the design. This statement may induce an over-estimated design for the bridge which have very good quality structures with casing covered drilled shafts and the PC-house contained pile cap. Because the assumption of free-head conditions (hinge connections) are unreal for the elevated pile cap system with multiple piles of the long span sea-crossing bridges. On the other hand, elastic displacement method to evaluate the pile reactions under the pile cap is not suitable for this type of bridges due to impractical assumptions. So, full modeling techniques which analyze the superstructure and the substructure simultaneously should be performed. Loads and stress state of the very large diameter drilled shaft and the pile cap for Incheon Bridge which will the longest bridge in Korea were investigated through the full modeling for rigid connection conditions.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.476-485
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• 2006

The connection system of steel pile and RC footing is an important structure, because the total load of upper construction should be transferred through this joint construction of different two materials-steel and RC-with strongly changed section area. Although many connection systems have been developed, their structural and economical efficiency and workability are often insufficient. Therefore, a new connecting system was developed to improve the problems of current systems. The divided arc plate could improve the workability and economical efficiency, structural efficiency could be reached by welding construction. The main purpose of the research is to evaluate the structural behavior of the new designed connection system through experiments and numerical analysis.

• Journal of the Korean Geotechnical Society
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• v.24 no.7
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• pp.61-73
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• 2008

Piles of a bridge pier are connected with the column through the pile cap (footing). Behavior of the pile foundation can be different according to the connection method between piles and the pile cap. Connection methods between pile heads and the pile cap are divided into two groups : rigid connections and hinge connections. Domestic design code has been specified to use rigid connection method for the highway bridge. In the rigid connection method, maximum bending moment of a pile occurs at the pile head and this helps the pile to prevent the excessive displacement. Rigid methods are also good to improve the seismic performance. However, some specifications prescribe that conservative results through investigations of both the fixed-head condition and the free-head condition should be reflected in the design. This statement may induce an over-estimated design for the bridge which has high-quality structures with casing covered drilled shafts and the PC-house contained pile cap. Because the assumption of free-head conditions (hinge connections) is unreal for the elevated pile cap system with multiple piles of the long span sea-crossing bridges. On the other hand, elastic displacement method to evaluate the pile reactions under the pile cap is not suitable for this type of bridges due to impractical assumptions. So, full modeling techniques which analyze the superstructure and the substructure simultaneously should be performed. Loads and stress state of the large diameter drilled shaft and the pile cap for Incheon Bridge which will be the longest bridge of Korea were investigated through the full modeling for rigid connection conditions.

• Structural Engineering and Mechanics
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• v.12 no.2
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• pp.201-214
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• 2001

Four finite element (FE) models are examined to find the one that best estimates moment-rotation characteristics of top- and seat-angle with double web-angle connections. To efficiently simulate the real behavior of connections, finite element analyses are performed with following considerations: 1) all components of connection (beam, column, angles and bolts) are discretized by eight-node solid elements; 2) shapes of bolt shank, head, and nut are precisely taken into account in modeling; and 3) contact surface algorithm is applied as boundary condition. To improve accuracy in predicting moment-rotation behavior of a connection, bolt pretension is introduced before the corresponding connection moment being surcharged. The experimental results are used to investigate the applicability of FE method and to check the performance of three-parameter power model by making comparison among their moment-rotation behaviors and by assessment of deformation and stress distribution patterns at the final stage of loading. This research exposes two important features: (1) the FE method has tremendous potential for connection modeling for both monotonic and cyclic loading; and (2) the power model is able to predict moment-rotation characteristics of semi-rigid connections with acceptable accuracy.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1607-1614
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• 2011

As the connection between spread footing and pile is very important structural connection, it acts as the inter-loading medium to transfer the rail loads applied by superstructure to ground through the body pile of foundation. The experimental study is the method how to reinforce the pile cap between steel pile and footing utilizing perfobond plate with protruding keys. It were experimented on the compression punching tests and bending moment tests against the vertical loading and horizontal loadings acting on head of steel tube pipe. As a result, the tension capacity of the perfobond plate exhibited the superior performance due to the interlocking or dowel effects by the sheared keys of perfobond plate, and there were showing the sufficient strength and ductile capacity against the bending moment of horizontal loading tests. Therefore, it is judged that "the embedded method of perfobond plate in pile cap and footing" which is utilizing the shear connection of perfobond plate with protruding keys has a sufficient structural stability enough to be replaced with the current specification of reinforced method of pile cap with vertically deformed rebar against the vertical compression loads and bending moments that are able to occur in the combination structure of steel pile and the footing foundation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.7
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• pp.689-697
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• 2007

This thesis suggests ways on how to enhance handset radiation power under head phantom condition. Generally, peak EIRP(Effective Isotropic Radiated Power) is used to measure the radiation performance. TRP is more effective to represent indication of mobile radiation performance in the field than EIRP. In this case, we measure the TRP as an index of radiation power. The factors which effect TRP are antenna length, antenna position, folder angle and ground connection method. More detailed analysis is performed over these items. Significant item is ground connection method between main PCB and folder GND. Using the FPCB we connect main GND to folder GND through the hinge near the antenna. The result is that TRP attenuation is decreased about 5 dB under head phantom condition.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.4
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• pp.443-451
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• 2007

The improvement of stiffness by the increase of thickness of deck plate or the reinforcement of longitudinal rib is one method among the effective methods to control fatigue damages occurring in orthotropic steel deck. It is likely that the increase of stiffness is effective to restrain local deformation caused by axial load in the steel deck. Therefore, in this study, the parameter studies for the reinforced structural details such as the bulk-head plate and vertical rib which is established to reduce the resultant stresses in the connection parts of the longitudinal rib and floor beam were performed with FE analysis. From the results, it was known that the reinforced structural detail with the bulk-head plate in the longitudinal ribs reduced overall the principal stresses at the connection parts, but the stress concentration increased in the weld toe parts which are occurring fatigue cracks. Also, it was estimated that the reinforced structural detail with the vortical rib in the longitudinal ribs because of the reduction of stress concentration in the weld toe parts is more effective details than the bulk-head plate.

• Journal of the Korean Society of Hazard Mitigation
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• v.2 no.2 s.5
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• pp.95-104
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• 2002

This paper presents the pull-out failure mode on Headed Bars and prediction of tensile capacity, as governed by concrete cone failure. 17 different plate types, three different concrete strengths and three different welding types of specimens were simulated. Test variables are the reinforcing bar diameters connected to headed plate (e.g., 16mm, 19mm and 22mm), the head plate shapes (e.g., circular, square, rectangular), the dimensions of head plates (e.g., area and thickness), the types of welding scheme for connection of reinforcing bars and head plates (e.g., general welding and friction welding). Headed Bars were manufactured in different areas, which shape and thickness are based on ASTM 970-98. Calculation of Embedment length in concrete is based on CSA 23.3-94, and static tensile load was applied. Pullout capacities tested were compared to the values determined using current design methods such as ACI-349 and CCD method. If compare experiment results and existings, Headed bar expressed high strength and bigger breakdown radious than standard by wide plate area and anomaly reinforcing rod unlike anchor.

• Journal of Haehwa Medicine
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• v.18 no.2
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• pp.131-140
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• 2009

The aim of this study is to find out benefits of symptom questionnaire for oriental medical treatments. We analyzed symptom questionnaire of Korean association of abdomen diagnosis and treatment. Conclusions are as below. 1. Appetite, taste and digestion have a deep connection with accumulation and muscular contracture, with which the method of reinforcement and reduction is decided. 2. Feces, urine and, sweat have a deep connection with accumulation and water, with which the method of diaphoresis, emesis and purgation is decided. 3. Thirst and chillness and fever have a deep connection with water poisons and feverish feeling, based on which the cold and heat is classified. 4. we can find out the lesions with departmentalized physical sections of the head and the face, the chest, the abdomen, the articulations, the limbs and the skin. 5. It is possible to select appropriate prescription and assess before & after treatment through the questionnaire.