• Journal of the Korean Society of Safety
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• v.7 no.3
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• pp.99-107
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• 1992

Weld bonding can be applied as a combined method of spot welding and adhesive to have more advantages than those. Weld bonding has many merits that enlarge the fatigue strength of spot Welding and also improve the creep of adhesive. But it has not beer proved well in the various environmental conditions. In this study, weld bonding test for fatigue properties and tensile strength is presented under such various coditions as temperatures, humidity, and etc.

• Korea-Australia Rheology Journal
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• v.18 no.4
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• pp.183-189
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• 2006

High internal phase emulsions are highly concentrated emulsion systems consisting of a large volume of dispersed phase above 0.74. The rheological properties of high internal phase water-in-oil emulsions were measured conducting steady shear, oscillatory shear and creep/recovery experiments. It was found that the yield stress is inversely proportional to the drop size with the exponent of values between 1 and 2. Since the oil phase contains monomeric species, microcellular foams can easily be prepared from high internal phase emulsions. In this study, the microcellular foams combining a couple of thickeners into the conventional formulation of styrene and water system were investigated to understand the effect of viscosity ratio on cell size. Cell size variation on thickener concentration could be explained by a dimensional analysis between the capillary number and the viscosity ratio. Compression properties of foam are important end use properties in many practical applications. Crush strength and Young's modulus of microcellular foams polymerized from high internal phase emulsions were measured and compared from compression tests. Of the foams tested in this study, the foam prepared from the organoclay having reactive group as an oil phase thickener showed outstanding compression properties.

• Steel and Composite Structures
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• v.3 no.3
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• pp.169-184
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• 2003

This paper presents a generic modelling of composite steel-concrete beams with elastic shear connection. It builds on the well-known seminal technique of Newmark, Siess and Viest, in order to formulate the partial interaction formulation for solution under a variety of end conditions, and lends itself well for modification to enable direct quantification of effects such as shrinkage, creep, and limited shear connection slip capacity. This application is possible because the governing differential equations are set up and solved in a fashion whereby inclusion of the kinematic and static end conditions merely requires a statement of the appropriate constants of integration that are generated in the solution of the linear differential equations. The method is applied in the paper for the solution of the well-studied behaviour of simply supported beams with partial interaction, as well as to provide solutions for a beam encastr$\acute{e}$ at its ends, and for a propped cantilever.

• Computers and Concrete
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• v.32 no.4
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• pp.383-392
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• 2023

The mechanical properties of Recycled Aggregate Concrete (RAC) with 100 percent Recycled Coarse Aggregate (RCA) under loading rates were investigated in depth. The theoretical model was validated utilizing the RAC elastic modulus obtained from cylindrical specimens subjected to various strain rates. Viscoelastic theories have traditionally been used to describe creep and relaxation of viscoelastic materials at low strain rates. In this study, viscoelastic theories were extended to the time domain of high strain rates. The theory proposed was known as reversed viscoelastic theory. Normalized Dirichlet-Prony theory was used as an illustration, and its parameters were determined. Comparing the predicted results to the experimental data revealed a high level of concordance. This methodology demonstrated its ability to characterize the strain rate effect for viscoelastic materials, as well as its applicability for determining not only the elastic modulus for viscoelastic materials, but also their shear and bulk moduli.

• International Journal of Highway Engineering
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• v.7 no.4 s.26
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• pp.203-210
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• 2005

The penetration and viscosity tests have been used for the evaluation of the aged asphalt binder performance change. The improved test method has been required because the conventional tests could not evaluate the viscoelastic characteristics and the real behaviour of the aged asphalt binder. The conventional test methods using a different short term aged asphalt binder were tested and the test results were expressed as the penetration index and the residual penetration. The oscillatory and rotational mode tests were performed to find out the rheological characteristics of the short term aged asphalt binder in this study. The test results showed that the change of testing frequency, the speed of the vehicle effects the complex modules and phase angles. The creep compliance and shear viscosity also showed the different test results when the short term aged asphalt binders were tested. The rheological behavior should consider when the pavement design is conducted.

• Journal of the Korean earth science society
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• v.33 no.5
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• pp.434-449
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• 2012

The Mesozoic leucocratic granite in the northeastern margin of the Taebaeksan Basin was transformed to protomylonite and mylonite. Mylonitic foliations generally strike to NWWNW and dip to NE with the development of a sinistral strike-slip (top-to-the-northwest) shear sense. Grain-size reduction of feldspar in the mylonitized leucocratic granite occurred due to fracturing, myrmekite formation and neocrystallization of albitic plagioclase along the shear fractures of K-feldspar porphyroclasts. As the deformation proceeded, compositional layering consisting of feldspar-, quartz- and/or muscovite-rich layers developed in the mylonite. In the feldspar-rich layer, fine-grained albitic plagioclase and interstitial K-feldspar were deformed dominantly by granular flow. On the other hand, quartz-rich layers containing core-mantle and quartz ribbons structures were deformed by dislocation creep. Based on calculations from conventional two-feldspar and ternary feldspar geothermometers, mylonitization temperatures of the leucocratic granite range from 360 to $450^{\circ}C$. It thus indicates that the mylonitization has occurred under greenschist-facies conditions. Based on the geochemical features and previous chronological data, the leucocratic granite was emplaced during the Middle Jurassic at volcanic arc setting associated with crustal thickening. And then the mylonitization of the granite occurred during the late Middle to Late Jurassic (150-165 Ma). Therefore, the mylonitization of the Jurassic granitoids in the Taebaeksan Basin was closely related to the development of the Honam shear zone.

• Journal of the Korean Graphic Arts Communication Society
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• v.23 no.2
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• pp.1-14
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• 2005

Generally, printing inks are composed of pigment, vehicle and additive. Among others, the vehicle transfers the pigment to substrate and then binds it on the surface. So, rheological properties of the vehicle are an important factor which has influence on printability. Thus, in this study, rheology of the vehicle was investigated by using rotational rheometer according to molecular weight of resin. Also, emlusion rheology of water in oil type and its microstructure were examined with increasing the shear rate. Consequently, the following results were obtained: (1) By viscometric flow test, zero shear viscosity and shear thinning index of vehicle increased with increasing the molecular weight of resin. (2) By relaxation and creep test, relaxation time and retardation time of vehicle increased with increasing the molecular weight of resin. (3) By frequency sweep test, crossover point of vehicle increased with increasing the molecular weight of resin. (4) G' and G" of emlusions increased with increasing the molecular weight by amplitude sweep test. (5) The shape of water drop in emlusions was changed to the capillary tube.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.3
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• pp.11-20
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• 2008

In this paper, the characteristics of low hardness high damping rubber bearings(HDRB) were studied through various prototype tests. The low hardness HDRB were tested to evaluate vertical stiffness, shear stiffness, equivalent damping ratio, various dependencies of shear properties, ultimate shear properties and other factors. The prototype test was performed according to the specifications of ISO 22762-1, and evaluated according to the specifications of ISO 22762-3. The results of the prototype test showed that shear strain and temperature were the factors that most greatly influenced shear stiffness, and that compressive stress was the factor that most greatly influenced the equivalent damping ratio. The frequency dependence test of shear properties showed that two general tendencies of frequency dependence could be observed. At frequencies over 0.1Hz, the changes in shear properties were small. However, at frequencies under 0.1Hz, the changes in shear properties rapidly decreased. The creep test and the ultimate shear test were also performed, and both of them satisfied the requirements of ISO 22762-3.

• Journal of the Korean Society of Hazard Mitigation
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• v.2 no.2 s.5
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• pp.105-113
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• 2002

Steel-Concrete composite girders have been used since early in the 1920's due to their advantages, which are lower weight, increasement of stiffness, slenderness, long span. However, in designing short to continuous composite bridges, negative moment occurs in mid-support and creates problems such as cracks in the concrete slab. Therefore, partially composite bridges are considered. In this time, slab-anchor is used in these. If the stiffness of shear connectors is insufficient, slip would happen at the contact surface. Partial interaction is the case that takes account of slips. In this paper, the evaluation of initial shear stiffness of slab-anchor in composite bridges is obtained from Push-Out specimen. Also, finite element analyses which uses the initial shear stiffness of slab-anchor got the experiment are carried out on simple composite girder and continuous composite girder. Futhermore, the ratio of composite according to various shear stiffness are investigated and the classification according to the ratio of composite is proposed.

• Journal of the Korea Concrete Institute
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• v.22 no.5
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• pp.685-694
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• 2010

As a eco-friendly material, Hwangtoh (red clay) has been studied for complete or partial replacement of portland cement. Most of existing studies focused on the material properties of the Hwangtoh concrete including the compressive strength, drying shringkage, and creep. In the present study, the shear strength of the beams made with the Hwangtoh concrete was tested. Further, bond strength of tension re-bars embedded in the Hwangtoh concrete was tested. One of the concrete tested consisted of activated Hwangtoh replacing 20% of the cement. The other consisted 100% activated. Hwangtoh replacing all the cement. The beam specimens were tested under two point static loading. The test result showed that the shear strength of activated Hwangtoh concrete beams replacing 20% and 100% of cement was equivalent to that of the ordinary portland cement concrete beam. However, the bond strength of activated Hwangtoh concrete replacing 100% of the cement was less than that of the ordinary portland cement concrete.