• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.219-221
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• 2006

Asymmetrical rolling was performed by rolling AA 1050 sheets with different velocities of upper and lower rolls. In order to study the effect of roll gap geometry on the evolution of strain states and textures during asymmetrical rolling, the reduction per rolling pass was varied. After asymmetrical rolling, the outer thickness layers depicted shear textures and the center thickness layers displayed a random texture. With decreasing reduction per an asymmetrical rolling pass, the thickness layers depicting shear textures increases. The strain states associated with asymmetrical rolling were investigated by simulations with the finite element method (FEM).

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.222-225
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• 2006

The effect of lubrication on the development of textures and Microstructure was studied by different lubricating condition during hot rolling of AA1050 aluminum alloy. Hot rolling without lubrication led to the evolution of the pronounced through-thickness texture gradients, whereas hot rolling with lubrication gave rise to the formation of uniform rolling texture in the whole thickness layer. The variation of texture and microstructure according to hot rolling condition are investigated by X-ray diffractometer (XRD) and Electron Back-Scattered Diffraction (EBSD). The experimental results were discussed base on the finite element method (FEM) simulation. FEM calculation reveals that a larger friction between roll and sheet causes the deviated strain state from a plane strain leading to the formation of shear textures in the thickness layers close to the surface.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.475-480
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• 2003

Latex modification of concrete provides the material with higher flexural strength. This increase in flexural strength can attribute to the crack-arresting action of polymer in concrete, and also to the bonding they provide between the matrix and aggregates. This experimental study presents the fracture behavior of 12 flexural reinforced concrete beams repaired or strengthened by latex-modified concrete with the main experimental variables such as overlay thickness, strength thickness, and shear reinforcement. The results are as follow: All beam specimens having shear reinforcement were failed by delamination rupture at concrete interface at about 80% of ultimate loading after flexural cracking. All specimens overlayed and strengthened by latex-modified concrete (LMC) showed higher ultimate flexural strength than OPC control specimen, but lower than LMC control specimen. This increase in flexural strength could attribute to the high bonding they provide between the matrix and aggregates. All specimens except two shear unreinforced showed quite similar and consistent displacement behavior. The effect of overlay and strength thickness on the load-displacement relationship were a small at this study.

• Nuclear Engineering and Technology
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• v.49 no.7
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• pp.1463-1471
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• 2017

In order to monitor the pipe thinning caused by flow-accelerated corrosion (FAC) that occurs in coolant piping systems, a shear horizontal ultrasonic pitch-catch waveguide technique was developed for accurate pipe wall thickness monitoring. A clamping device for dry coupling contact between the end of the waveguide and pipe surface was designed and fabricated. A computer program for multi-channel on-line monitoring of the pipe thickness at high temperature was also developed. Both a four-channel buffer rod pulse-echo type and a shear horizontal ultrasonic waveguide type for high-temperature thickness monitoring system were successfully installed to the test section of the FAC proof test facility. The overall measurement error can be estimated as ${\pm}10{\mu}m$ during a cycle from room temperature to $200^{\circ}C$.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.4
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• pp.1102-1115
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• 1995

An experimental study on the flow over the axisymmetric backward-facing step was carried out. The purpose of the present study is to investigate the effect of the boundary layer thickness at the separation point on the reattachment length and to understand the structure of the recirculating flows. Local mean and fluctuating velocity components were measured in the separating and reattaching axisymmetric turbulent boundary layer over the wall of convex cylinder placed in a water tunnel by using 2-color 4-beam fiber optics laser Doppler velocimetry. The study demonstrated that the reattachment length increases with increasing boundary layer thickness. It was also observed that the reverse flow velocity and turbulent kinetic energy decrease with an increase in the momentum thickness at the separation point. The measured velocity field suggests that the boundary layer thickness at the separation can affect definitely on the formation of corner eddy.

• Structural Engineering and Mechanics
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• v.58 no.6
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• pp.1001-1020
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• 2016

The study is to investigate the free vibration of antisymmetric angle-ply conical shells having non-uniform sinusoidal thickness variation. The arbitrarily varying thickness is considered in the axial direction of the shell. The vibrational behavior of shear deformable conical shells is analyzed for three different support conditions. The coupled differential equations in terms displacement and rotational functions are obtained. These displacement and rotational functions are invariantly approximated using cubic spline. A generalized eigenvalue problem is obtained and solved numerically for an eigenfrequency parameter and an associated eigenvector of spline coefficients. The vibration characteristic of the shells is examined for cone angle, aspect ratio, sinusoidal thickness variation, layer number, stacking sequence, and boundary conditions.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.401-412
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• 1998

The aim of this study was to measure the regional micro-shear bond strength of dentin bonding agents to dentin, and to investigate the relationship between the micro-shear bond strength and two dentinal characteristics ; Vickers hardness and remaining dentin thickness. Twenty-four freshly extracted, noncarious human molars were selected for this study. The materials tested in this study consisted of two commercially available dentin bonding agents (MAC-BOND, ONE-STEP) and two restorative light-cured composite resins (AELITEFIL, Z100). The occlusal or side surface of tooth crown was sectioned to expose dentin, and the exposed surface was finally polished with # 600 sandpaper. Four groups of application methods were used combining the filling materials and the dentin bonding agents. The composite resin-attached tooth specimens were embeded in a cold cure acrylic resin, and were cut with a low speed diamond saw to the dimension of 1mm $\times$ 1mm. Nine specimens were obtained from each tooth. The cut specimens were divided into three groups depending on the position of the dentin bonding surface. The micro-shear bond strength, remaining dentin thickness, and dentinal hardness were measured. Experimental results were then statistically analyzed with ANOVA. t-test, Scheffe test, and regression analysis. From this experiment, the following results were obtained : 1. In the case of occlusal surface bonding, the pooled micro-shear bond strength of ONST-AELIT group (16.62 MPa) was significantly higher than that of MACB-AELIT group (9.91 MPa) (p<0.05). However, there was no significant difference in the micro-shear bond strength depending on the dentin position (p>0.05). 2. In the case of side surface bonding of crown, the pooled micro-shear bond strength of four different bonding groups was not significantly different among each other (p>0.05). However, in three of the test groups (ONST-AELIT, MACB-Z100, ONST-Z100), the micro-shear bond strength to the lower 1/3(III) position was significantly lower than that to middle 1/3(II) position of surface (p<0.05). 3. In the ONST-AELIT bonding group, the pooled micro-shear bond strength to the occlusal surface was significantly lower than that to the side surface of crown (p<0.05). 4. There was no significant correlation between the micro-shear bond strength and dentin hardness / remaining dentin thickness (p>0.05).

• Geomechanics and Engineering
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• v.10 no.6
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• pp.827-836
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• 2016

The rate of softening is an important factor to determine whether the failure occurs along localized shear band or in a more diffused manner. In this paper, strength loss and softening rate effect depending on sensitivity are investigated for weakly cemented clays, for both artificially cemented high plasticity San Francisco Bay Mud and low plasticity Yolo Loam. Destructuration and softening behavior for weakly cemented sensitive clays are demonstrated and discussed through multiple vane shear tests. Artificial sensitive clays are prepared in the laboratory for physical modeling or constitutive modeling using a small amount of cement (2 to 5%) with controlled initial water content and curing period. Through test results, shear band thickness is theoretically computed and the rate of softening is represented as a newly introduced parameter, ${\omega}_{80%}$. Consequently, it is found that the softening rate increases with sensitivity for weakly cemented sensitive clays. Increased softening rate represents faster strength loss to residual state and faster minimizing of shear band thickness. Uncemented clay has very low softening rate to 80% strength drop. Also, it is found that higher brittleness index ($I_b$) relatively shows faster softening rate. The result would be beneficial to study of physical modeling for sensitive clays in that artificially constructed high sensitivity (up to $S_t=23$) clay exhibits faster strain softening, which results in localized shear band failure once it is remolded.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.2
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• pp.13-19
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• 2000

Shear strengths of BGA solder joints on Cu pads were studied for Cu-containing Sn (0, 1.5, and 2.5 wt.% Cu) and Sn-40Pb (0 and 0.5wt.% Cu) solders, with emphasis on the roles of the Cu-Sn intermetallic layer thickness and the roughness of the interface between the intermetalic layer and solder. The shear strength test was performed for as-soldered solder joints with various soldering reaction times up to 4 min. The addition of Cu to the pure Sn solder results in an enhanced growth of the intermetallic layer whereas the effect of Cu addition to the Sn-40Pb solder is primarily on the reduction of the roughness of the intermetallic/solder interface. The critical thickness of the intermetallic layer for a maximum shear strength depends on the solder materials, which was measured to be ~ 2.3 $\mu\textrm{m}$ for Sn-Cu solders and ~ 1.2 $\mu\textrm{m}$ for Sn-Pb-Cu solders. The shear strength at the critical intermetallic layer thickness seems to increase as the intermetallic/solder interface becomes rougher. This is in accordance with the observation that the sheared fracture occurred initially within the solder tends to shift towards the intermetallic/solder interface as the intermetallic layer grows above the critical thickness.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.1
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• pp.9-17
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• 2015

The basic flow configuration is composed of a plane, double shear layer where relatively thin mid gas layer is sandwiched between air and fuel stream. The present study describes numerical investigations concerning the combustion enhancement according to a variation of mid layer thickness. In this case, the effect of heat release in turbulent mixing layers is important. For the numerical solution, a fully conservative unsteady $2^{nd}$ order time accurate sub-iteration method and $2^{nd}$ order TVD scheme are used with the finite volume method including k-${\omega}$ SST model. The results consists of three categories; single shear layer consists of fuel and air, inert gas sandwiched between fuel and air, cold fuel gas sandwiched between fuel and air. The numerical calculations has been carried out in case of 1, 2, 4 mm of mid layer thickness. The height of total gas stream is 4 cm. The combustion region is broadened in case of inert gas layer of 2, 4 mm thickness and cold fuel layer of 4 mm thickness compared with single shear layer.