• Journal of the Microelectronics and Packaging Society
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• v.9 no.2
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• pp.39-43
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• 2002

The eutectic solder Sn-37Pb and the lead free solder alloys with the compositions of Sn-0.7Cu, Sn-3.5Ag, Sn-3.5Ag-0.75Cu, Sn-2.0Ag-0.7Cu-3.0Bi were applied to the 48 BGA packages, and then it was discussed for the shear strength at the solder joints as the hardness and the composition of the small solder ball. As a result of experiments, the high degree of hardness with the displacement of 0.043 mm was obtained in Sn-2.0Ag-0.7Cu-3.0Bi. The shear strength of the lead free solder was higher than that of Sn-37Pb solder, and it can be obtained the maximum value of about 52% in Sn-2.0Ag-0.7Cu-3.0Bi.

• Journal of Ocean Engineering and Technology
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• v.22 no.4
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• pp.51-58
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• 2008

The objective of this study was to investigate the mechanical characteristics of fiber-reinforced lightweight soil using waste fishing net or monofilament for recycling both dredged soils and bottom ash. Reinforced lightweight soil consists of dredged soil, cement, air foam, and bottom ash. Waste fishing net or monoiament was added the mixture in order to increase the shear strength of the lightweight soil. Test specimens were fabricated with various mixing conditions, including waste fishing net content and monofilament content. Several series of unconfined compression tests and direct shear tests were carried out. From the experimental results, it was found that the unconfined compressive strength, as well as the stress-strain behavior of reinforced lightweight soil was strongly influenced by mixing conditions. In this study, the maximum increase in shear strength was obtained with either a 0.5% content of monofilament or 0.25% waste fishing net. The unconfined compressive strength of reinforced lightweight soil with monofilament was greater than that of reinforced lightweight soil with waste fishing net.

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2367-2374
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• 2024

In this paper, based on the need for high-strength connections between all-tungsten-oriented plasma materials and thermal sinking materials of copper and its alloys in nuclear fusion devices, a study on the effect of tungsten surface laser micro structuring on the interfacial bonding properties of W/Cu joints was carried out. In the experiment, the connectors were prepared by vacuum fusion infiltration technology, and the effects of microgroove structure on the mechanical and thermal conductivity of W/Cu connectors were investigated under different parameters (including microgroove pitch, microgroove depth, and microgroove taper). The maximum shear strength is 126.0 MPa when the pitch is 0.15 mm and the depth is 34 ㎛. In addition, the negative taper structure, i.e., the width of the entrance of the microstructure is smaller than the width of the interior of the microstructure, is also investigated. The shear tests show that there is an approximately linear relationship between the shear strength of W/Cu and taper. Compared with the positive taper, the shear strength of the samples with the same morphological density and depth of the tungsten surface is significantly higher.

• Magazine of the Korean Society of Agricultural Engineers
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• v.31 no.3
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• pp.57-69
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• 1989

The study was carried out for the strength parameter of coarse grained Soil and slope stability analysis of earth dam. The test samples were taken fifteen kinds of soil from cohesive soil to coarse gravel. The degree of compaction of test samples for shear test and permeability test was chosen 95 percentage of maximum dry density. The results of this study are as follows ; 1.The maximum dry density(Yd) of coarse grained soil increase in proportion to coarse particles(P) with the relation of Y d= 1.609+0.0043P. 2.The coefficients of permeability(k) decrease by the increase of fine particles(n) with the relation of k=0.0426e-0 185n. 3.The cohesions of soil decrease by the increase of coarse particles, but internal friction angles are more increased in same condition. 4.The internal friction angles(${\Phi}$) decrease in inverse proportion to void ratio(e) with the relation of ${\Phi}$ = 73.068 - 69.268e. 5.The strength parameters( Ct ${\Phi}$t) by triaxial compression test are clearly smaller than that (Cd, ${\Phi}$d) by direct shear test in fine grained soil, but the differences between both parameters are a little in coarse grained soil.The relations of both parameters are as follows; Ct = O.544Cd + 0.04 ${\Phi}$t= 1.282${\Phi}$d-2306 6.In cohesive soil, the strength parameters( Cl ${\Phi}$l) by large size shear test apparatus are similar to the strength parameters(Cs , ${\Phi}$s) by small size shear test appratus, but Cs and ${\Phi}$s values are larger than Cl and ${\Phi}$l values from 10 percentage to 20 percentage in coarse grained soil. 7.The fine grained soil is inappropriate to high dam more than 20 meters and it must be taken coarse grained soil with high internal friction angle for high dam.

• Journal of the Korean Geotechnical Society
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• v.25 no.12
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• pp.57-67
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• 2009

Along with the advanced construction technologies, the maximum size of coarse aggregate used for dam construction ranges from several cm to 1m. Testing the original gradation samples is not only expensive but also causes many technical difficulties. Generally, indoor tests are performed on the samples with the parallel grading method after which the results are applied to the design and interpretation of the actual geotechnical structure. In order to anticipate the exact behavior characteristics for the geotechnical structure, it is necessary to understand the changes in the shear behavior. In this study, the Large Triaxial Test was performed on the parallel grading method samples that were restructured with river bed sand-gravel, with a different maximum size, which is the material that was used to construct Dam B in Korea. And the Stress - Strain characteristics of the parallel grading method samples and the characteristics of the shear strength were compared and analyzed. In the test results, the coarse-grained showed strain softening and expansion behavior of the volume, which became more obvious as the maximum size increased. The internal angle of friction and the shear strength appeared to increase as the maximum size of the parallel grading method sample increased.

• Journal of the Korean Geotechnical Society
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• v.33 no.12
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• pp.7-20
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• 2017

In this study, effects of grain size distribution on the shear strength and rheological properties are investigated for coarse- and fine-grained soils by using direct shear apparatus. Shear strengths are estimated for fine-grained soils with the maximum particle size of 0.075 mm and coarse-grained soils with the maximum particle size of 0.425 mm and fine contents of 17% prepared at dry and liquid limit states. The direct shear tests are conducted under the relatively slow shear velocity, which corresponds to the reactivated landslide or debris flow after collapse according to the landslide classification. In addition, for the evaluation of rheological properties, residual shear strengths for both fine- and coarsegrained soils prepared under liquid limit states are obtained by multiple reversal shear tests under three shear velocities. From the relationship between residual shear strengths and shear rates, Bingham plastic viscosity and yield stress are estimated. The direct shear tests show that cohesions of fine-grained soil are greater than those of coarse-grained soil at both dry and liquid limit states. However, internal friction angles of fine-grained soil are smaller than those of coarse-grained soil. In case of rheological parameters, the plastic viscosity and yield stress of fine-grained soils are greater than those of coarse-grained soils. This study may be effectively used for the prediction of the reactivated landslide or debris flow after collapse.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.5
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• pp.111-117
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• 2019

Shear experiments were carried out to evaluate shear performance of SFRC deep beams with end-anchorage of SD600 high strength headed reinforcing tensile bars. The experimental variables include the end-anchorage methods of tensile bars (headed bar, straight bar), the end-anchorage lengths, and the presence of shear reinforcement. Specimens with a shear span ratio of 1 showed a pattern of the shear compression failure with the slope cracks progressed after the initial bending crack occurred. Specimens with end-anchorage of headed bars (H-specimens) showed a larger shear strengths of 5.6% to 22.4% compared to straight bars (NH-specimens). For H-specimens, bearing stress reached 0.9 to 17.2% of the total stress of tensile bars up to 75% of the maximum load, and reached 22.4% to 46%. This shows that the anchorage strength due to the bearing stress of headed bars has a significant effect on shear strength. The experimental shear strength was 2.68 to 4.65 times the theoretical shear strength by the practical method, and the practical method was evaluated as the safety side.

• Journal of the Korea Concrete Institute
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• v.24 no.4
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• pp.407-414
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• 2012

The purpose of this study is to experimentally investigate the shear behavior of reinforced concrete beams embedded with GFRP (glass fiber reinforced polymer) plate with openings. In this study, the parameters include the shape of reinforcement, reinforcement area, and thickness and width of reinforcements. The test was performed on 9 specimens with shear spanto-depth ratio of 2.8. When the reinforcement area was varied, the GFRP plate showed 3.6 times greater shear strength than steel stirrup. The test result showed that shear strength increased as reinforcement area increased. Also, when the shape of a parallelogram GFRP plate was used, it showed higher shear strength than that with rectangular shape. Effect of thickness and width of reinforcement showed that shear capacity increased as width increased. For a comparison study, a calculation of the shear strength of reinforced beams with GFRP plate based on the ACI 318M-08 was compared with the test results. The test results were compared with the maximum shear reinforcement areas required by ACI 318M-08, CSA-04, and EC2-02 provision.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.1
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• pp.58-64
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• 2003

A mechanical press joining was investigated in ender for joining A1-5052 sheets for automobile body weight reduction. Static tensile and fatigue tests were conducted using tensile-shear specimens for evaluation of fatigue strength of the joint. During Tox joining process for A1-5052 plates, using the current sheet thickness and punch diameter, the optimal applied punching force was found to be 32 kN under the current joining condition. For the static tensile-shear experiment results, the fracture mode is classified into interface fracture mode, in which the neck area fractured due to influence of neck thickness, and pull-out fracture mode due to influence of plastic deformation of the joining area. And, during fatigue tests for the A1-5052 tensile shear specimens, interface failure mode occurred in the region of low cycle. The fatigue endurance limit approached to 6 percents of the maximum applied load, considering fatigue lifetime of $2.5\times10^6$ cycles.

• Journal of Korean Association for Spatial Structures
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• v.21 no.2
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• pp.49-56
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• 2021

The damage to non-structural elements in buildings has been increasing due to earthquakes. In Korea, post-installed anchors produced overseas have been mainly used for seismic anchorage of non-structural components to structures. Recently, a new cast-in-place concrete insert anchor installed in concrete without drilling has been developed in Korea. In this paper, an experimental study was conducted to evaluate the tensile and shear strengths of the newly developed anchor under monotonic load. The failure modes of the tension specimens were divided into concrete breakout failure and steel failure, and all shear specimens showed steel failure. In both tension and shear, the maximum loads of specimens were greater than the nominal strengths predicted by the concrete design code (KDS 14 20 54). As a result, it is expected that the current code can also be used to calculate the strength of the developed cast-in anchor.