• Advances in nano research
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• v.14 no.2
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• pp.141-154
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• 2023

Effects of viscoelastic foundation on vibration of curved-beam structure with clamped and simply-supported boundary conditions is investigated in this study. In doing so, a micro-scale laminate composite beam with two piezoelectric face layer with a carbon nanotube reinforces composite core is considered. The whole beam structure is laid on a viscoelastic substrate which normally occurred in actual conditions. Due to small scale of the structure non-classical elasticity theory provided more accurate results. Therefore, nonlocal strain gradient theory is employed here to capture both nano-scale effects on carbon nanotubes and microscale effects because of overall scale of the structure. Equivalent homogenous properties of the composite core is obtained using Halpin-Tsai equation. The equations of motion is derived considering energy terms of the beam and variational principle in minimizing total energy. The boundary condition is assumed to be clamped at one end and simply supported at the other end. Due to nonlinear terms in the equations of motion, semi-analytical method of general differential quadrature method is engaged to solve the equations. In addition, due to complexity in developing and solving equations of motion of arches, an artificial neural network is design and implemented to capture effects of different parameters on the inplane vibration of sandwich arches. At the end, effects of several parameters including nonlocal and gradient parameters, geometrical aspect ratios and substrate constants of the structure on the natural frequency and amplitude is derived. It is observed that increasing nonlocal and gradient parameters have contradictory effects of the amplitude and frequency of vibration of the laminate beam.

• Journal of Computational Design and Engineering
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• v.3 no.3
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• pp.198-214
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• 2016

Oval substrates are widely used in automobiles to reduce the exhaust emissions in Diesel oxidation Catalyst of CI engine. Because of constraints in space and packaging Oval substrate is preferred rather than round substrate. Obtaining the flow uniformity is very challenging in oval substrate comparing with round substrate. In this present work attempts are made to optimize the inlet cone design to achieve the optimal flow uniformity with the help of CATIA V5 which is 3D design tool and CFX which is 3D CFD tool. Initially length of inlet cone and mass flow rate of exhaust stream are analysed to understand the effects of flow uniformity and pressure drop. Then short straight cones and angled cones are designed. Angled cones have been designed by two methodologies. First methodology is rotating flow inlet plane along the substrate in shorter or longer axis. Second method is shifting the flow inlet plane along the longer axis. Large improvement in flow uniformity is observed when the flow inlet plane is shifted along the direction of longer axis by 10, 20 and 30 mm away from geometrical centre. When the inlet plane is rotated again based on 30 mm shifted geometry, significant improvement at rotation angle of $20^{\circ}$ is observed. The flow uniformity is optimum when second shift is performed based on second rotation. This present work shows that for an oval substrate flow, uniformity index can be optimized when inlet cone is angled by rotation of flow inlet plane along axis of substrate.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.1
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• pp.15-22
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• 2017

This study focuses on the investigation of bond strength of magnesium potassium phosphate cement mortar(MKPC) according to moisture condition of substrate. Tensile bond test, shear bond test and interfacial bond test are adopted for evaluating the adhesion characteristics of MKPC to conventional cement mortar substrate. The main experimental variables are test methods and moisture levels of substrate. Because the moisture condition of the substrate may be critical to achieving bond, optimum moisture condition for a conventional concrete substrate has evaluated in this study. The results are as follows ; The effects of moisture condition at substrate into the bonding of MKPC are less different than polymer cement mortar and epoxy mortar. But the saturated and surface dry condition is the most appropriate moisture level among the considered, followed by saturated condition and wet condition. Thus, an adequate moisture level of substrate for MKPC is essential for good bond strength.

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.10a
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• pp.18-18
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• 1997

• Proceedings of the Korean Magnestics Society Conference
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• 1995.10a
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• pp.94-95
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• 1995

• The Magazine of the IEIE
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• v.28 no.4
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• pp.101-102
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• 2001

• Proceedings of the Korean Vacuum Society Conference
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• 2005.08a
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• pp.149-149
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• 2005

• Bulletin of the Korean Chemical Society
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• v.19 no.10
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• pp.1029-1031
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• 1998

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.106-107
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• 2009

In this study, We investigated the effects of substrate temperature on the electrical and optical properties of Ga-, B-codoped ZnO(GZOB) thin films. GZOB thin films were deposited on glass substrate with various substrate temperature in the range from R.T. to $500\;^{\circ}C$ by DC magnetron sputtering. In the reslt, GZOB films at $400\;^{\circ}C$ exhibited a low resistivity value of $8.67\;{\times}\;10^{-4}\;{\Omega}-cm$, and a visible transmission of 80% with a thickness of 300 nm. This result indicated that the addition of Ga and B in ZnO films leads to the improvement of conductivity and transparent. From the result, we can confirm the possibility of the application as transparent conductive electrodes.

• Journal of the Korean Ceramic Society
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• v.29 no.12
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• pp.926-934
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• 1992

Uniform diamond films in a few $\textrm{mm}^2$ size and locally isolated diamond single crystals in size of 60 $\mu\textrm{m}$ were synthesized on Si-wafer and Al2O3 substrate by the method of acetylene flame. The effects of substrate temperature and flow ratio of oxygen to acetylene on the morphology of deposited diamond were investigated. According to the observations of growth behavior of diamond on Si substrate with respect to substrate surface pretreatment and flow ratio, it was shown that well faceted diamonds could grow uniformly when flow ratio was above 0.9 and substrates were densely scratched. With increasing substrates temperature, the crystal morphology changes from octahedron bounded by only {111} plane below 850$^{\circ}C$ to cubo-octahedron with almost equal development of {111} and {100} plane in the temperature range of 850∼950$^{\circ}C$. Between 950∼1050$^{\circ}C$, the {111} faces become rough and concave. Above 1050$^{\circ}C$, new crystallites begin to grow on concave {111} surface and overall morphology looks like cubo-octahedron with degenerated {111} faces. These changes of morphology can be understood in terms of the different growth mode of each crystallographic plane with respect to the substrate temperature and supersaturation. And the observed phenomena on {111} planes can be related to the face instability and twin generation.