• Journal of the Korean Society of Industry Convergence
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• v.22 no.6
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• pp.615-626
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• 2019

In this study, the applicability of PHC pile jointing method using rectangular steel tubular was studied. PHC pile joints are welded and bolt assembly. The bolt assembly method is a method that improves the various problems of welded joints. Numerical analysis and tests were conducted to analyze the applicability of the PHC pile jointing method using a rectangular steel tubular. The tests were carried out to test the material properties of the rectangular steel tubular material and the bending test of the pile joints. The numerical analysis was interpreted in the same conditons as the tests conditions. As a result, the material strength of each rectangular steel tubular could be used as a joint material. In the bending test, it was evaluated as a sTable material above the allowable stress of piles. In the numerical analysis results under the same conditions as the tests, it was possible to apply the pile joint material without exceeding the allowable stress of the material.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.64-71
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• 2010

It is suggested that the service life of the continuous welded rail(CWR) is estimated by the relationship between the rail surface irregularity according to the accumulated passing tonnage and bending fatigue of welded part in CWR. In this study, based on the results of bending fatigue tests of rail and results of measuring tests in situ of rail bending stress, this study estimated the bending fatigue life of welded rail in concrete track, adopting a Haibach's rule. The bending fatigue life of CWR considered the rail surface irregularity, train speed and the S-N curve by types of rail welding. In addition, this study estimated it for the fracture probability 1%, 0.1%, 0.01%. Therefore, this study proposed bending fatigue life of CWR in concrete track.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2003.05a
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• pp.109-113
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• 2003

In this experiment, we distribute the bending angle to 60$^{\circ}$, 90$^{\circ}$, 120$^{\circ}$, and we separate it in to two groups. One is straightening right after bending and the other is straightening after one week. The bars we will use are HD13 and HD16. The number of tests will be 60 times. In the case of HD16, the increase of bending angle decreased yield strength and maximum strength. And compared with thinner bars, HD16 showed bigger differences in yield strength and maximum strength when the 'being bent' duration got longer. So it shows that when we bend and after straighten a bar, stress change takes place on the surface of the bar. At the beginning it shows it's ductility after that it deforms while transforming it's character to destroying. And also, if we straighten a bar after bending, it doesn't get straighten like the original form. So it makes torsion and this torsion makes moments in different areas.

• Journal of Sensor Science and Technology
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• v.25 no.1
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• pp.27-34
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• 2016

This paper describes the development of a rehabilitation robot that can provide wrist bending exercise to a severe stroke patient staying in a bed ward or at home. The developed rehabilitation robot has a three-axis force sensor which detects three directional force Fx, Fy, and Fz. The sensor measures a bending force (Fz) exerted on the wrist and the signal force (Fx and Fy) which can be used for the safety purpose. The robot was designed for severe stroke patients in bed, and the robot program was developed to perform a wrist bending rehabilitation exercise. In our tests including a nine-day experimental exercise, the developed force sensor-based robot operated effectively and safely.

• Composites Research
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• v.19 no.6
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• pp.23-31
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• 2006

We measured mechanical properties, including Young's modulus, effective bending modulus and nominal fracture strength of nanohoneycomb structures using an Atomic Force Microscope(AFM) and a Nano-Universal Testing Machine(UTM). Anodic aluminum oxide(AAO) films are well suited as nanohoneycomb structures because of the simple fabrication process, high aspect ratio, self-ordered hexagonal pore structure, and simple control of pore dimensions. Bending tests were carried out for cantilever structures by pressing AFM tips, and the results were compared with three-point bending tests and tensile tests using a Nano-UTM. One side of the AAO films is clogged by harrier layers, and looks like a face material of conventional sandwich structures. Analysis of this layer showed that it did not influence the bending rigidity, and was just a crack tip. The present results can act as a design guideline in applications of nanohoneycomb structures.

• Journal of Korean Society of Steel Construction
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• v.15 no.1
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• pp.87-96
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• 2003

The Ssteel-Cconcrete (SC) Ccomposite Ccolumn is a new Ccomposite Ccolunin system, where hoops are welded between flanges of H-shapesd steel and concrete is filled in spaces between flanges are filled with con crete. Tests of SC composite columns were performed previously to determine their compression, bending and shear strength, and it showed good structural behavior. But sSince a column is usually subjected to an axial compression force, and bending it ihas needed to be bent forevaluate its structural behavior to be evaluated when its axial load and bending isaresimultaneously applied to the SC composite column. In this paper, tests were conducted to investigate the bending strength of SC composite columns subjected to axial compression force and bending moment. The parameters of the tests were concrete, a stud bolt, a hoop and a magnitude of axial compression. The test results showed that the maximum bending strength and ductility of an SC composite column were increased by 33-42% and 33-63%, respectively, comparinged to those of a bare steel column. Also, the results obtained bywith the Korean Limit State Design Code (LSD) presents a considerably safe side value compared to those of the Eurocode-4 and the Japan Code. However, wWhen the axial compression force is was increased, however, there awere considerable differences between the maximum strength obtained by the test and the LSD analysis. For this reason, it is recommended tothe use of the Eurocode-4 is recommended when calculates the strength of an SC composite column is being calculated, since the Eurocode-4 gives us a better estimation.

• Journal of the Korean Wood Science and Technology
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• v.35 no.6
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• pp.118-125
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• 2007

To obtain design data for built-up beams used as headers in light-frame timber construction, three members of $2{\times}6$ ($38{\times}140 mm$), $2{\times}8$ ($38{\times}184 mm$), $2{\times}10$ ($38{\times}235 mm$) and $2{\times}12$ ($38{\times}286 mm$) were built up as specimens of bending tests. The bending strengths of built-up headers were obtained through bending tests of these specimens, and it was considered that span tables can be calculated for various loading conditions based on the bending strengths of built-up headers. The bending strengths of built-up headers were determined as the bending stresses at 10 mm deflection of specimens from the results of bending tests of built-up beam specimens. Span tables for built-up headers were considered to be obtained by assuming five loading conditions for headers used in exterior walls and two loading conditions for headers used in interior walls. Among these 7 loading conditions, 5 loading conditions applied to headers in exterior walls included dead loads, live loads and snow loads and 2 loading conditions applied to headers in interior walls included dead loads and live loads.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.61-66
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• 2001

Fracture behaviors of pipes with local wall thinning is very important for the integrity of nuclear power plant. In pipes of energy plants, sometimes, the local wall thinning may result from severe drosion-corrosion damage. However, effect of local wall thinning on strength and fracture behaviors of piping system were not well studied. In this paper, the monotonic bending tests were performed of full-scale carbon steel pipes with local wall thinning. A monotonic bending load was applied to straight pipe specimens by four-point loading at ambient temperature without internal pressure. From the tests, fracture behaviors and fracture strength of locally thinned pipe were manifested systematically. The observed failure modes were divided into four types; ovalization, ovalization+cracking, local buckling and local buckling+cracking. Also, maximum load was successfully evaluated.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_2
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• pp.1135-1144
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• 2023

In this paper, bending strength and permeability tests were conducted on concrete permeable blocks manufactured by recycling industrial by-products of oyster shell and blast furnace slag to measure and compare bending strength and permeability coefficient, and present experimental research results. To this end, a total of 54 specimens with a size of 200x200x60mm for surface layer and base layer were manufactured, and bending strength and permeability test were carried ourt accoridng to KS F 4419. Eighteen types of mixing designs were implemented by varying the mixing and replacement rates of oyster shells and blast furnace slag. As a result of the experiment, the higher the mixing ratio of oyster shell, the lower the bending strength and the permeability coefficient. Thereafter, a total of three permeable blocks with dimensions of 200x200x60mm were manufactured and subjected to bending strength and permeability tests according to KS F 4419. As a result of the test, the bending strength satisfies the standard of KS F 4419, and the permeability coefficient is 12 times higher than the standard of KS F 4419. It seems that the proper mixing of oyster shells and blast furnace slag increases the amount of air, and further research on durability and economic feasibility of materials used to manufacture permeable blocks is required.

• 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.