• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.851-856
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• 1997

This study is on the estimation of the tool temperature for different tool nose radius and cutting conditions in turning. The experiment has been performed in different cutting conditions such as cutting speed, feed rate, and depth of cut for the tool nose radius, 0.4R, 0.8R using SMC workpiece materials. Tool temperature is measured using thermo-couple which is embedded in the insert tip. Using a multiple linear regression method, the tool temperature can be determined as an exponential equation with cutting variables and tool nose diameters for different tool materials. The equations determined in this study show a good correlation for the cutting conditions and can be used for the tool temperature estimation. The result indicates that the tool temperature decreases for ~ncreasing the tool nose radius in general. Also, nose radius hardly influences on the tool temperature compared with cutting speed, feed rate and depth of cut.

• Advances in materials Research
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• v.6 no.3
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• pp.279-301
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• 2017

Thermo-mechanical vibration characteristics of in homogeneousporous functionally graded (FG) micro/nanobeam subjected to various types of thermal loadings are investigated in the present paper based on modified couple stress theory with consideration of the exact position of neutral axis. The FG micro/nanobeam is modeled via a refined hyperbolic beam theory in which shear deformation effect is verified needless of shear correction factor. A modified power-law distribution which contains porosity volume fraction is used to describe the graded material properties of FG micro/nanobeam. Temperature field has uniform, linear and nonlinear distributions across the thickness. The governing equations and the related boundary conditions are derived by Extended Hamilton's principle and they are solved applying an analytical solution which satisfies various boundary conditions. A comparison study is performed to verify the present formulation with the known data in the literature and a good agreement is observed. The parametric study covered in this paper includes several parameters such as thermal loadings, porosity volume fraction, power-law exponents, slenderness ratio, scale parameter and various boundary conditions on natural frequencies of porous FG micro/nanobeams in detail.

• Structural Engineering and Mechanics
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• v.70 no.3
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• pp.351-365
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• 2019

In this paper, free vibration of Cooper-Naghdi micro sandwich cylindrical shell with saturated porous core and reinforced carbon nanotube (CNT) piezoelectric composite face sheets is investigated by using first order shear deformation theory (FSDT) and modified couple stress theory (MCST). The sandwich shell is subjected to magneto-thermo-mechanical loadings with temperature dependent material properties. Energy method and Hamilton's principle are used for deriving of the motion equations. The equations are solved by Navier's method. The results are compared with the obtained results by the other literatures. The effects of various parameters such as saturated porous distribution, geometry parameters, volume fraction and temperature change on the natural frequency of the micro-sandwich cylindrical shell are addressed. The obtained results reveal that the natural frequency of the micro sandwich cylindrical shell increases with increasing of the radius to thickness ratio, Skempton coefficient, the porosity of the core, and decreasing of the length to radius ratio and temperature change.

• Proceedings of the KWS Conference
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• 2003.05a
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• pp.210-212
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• 2003

Finite element analysis of welding processes, which entail phase evolution, heat transfer and deformation, is considered in this paper. Attention focuses on numerical implementation of the thermo-elastic-plastic constitutive equation proposed by Leblond et al in consideration of the transformation plasticity. Based upon the multiplicative decomposition of deformation gradient, hyperelastic formulation is employed for efficient numerical integration, and the algorithmic consistent moduli for elastic-plastic deformations including transformation plasticity are obtained in the closed form. The convergence behavior of the present implementation is demonstrated via a couple of numerical example.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.11
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• pp.96-102
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• 2002

This study is on the estimation method of toot temperature for different tool nose radius and cutting conditions in turning. Experimental analysis has been performed in different cutting conditions such as cutting speed, feed rate, and depth of cut for the tool nose radius, 0.4R, 0.8R using SMC workpiece materials. Tool temperature is measured using a thermo-couple which is embedded in the insert tip. Using multiple linear regression method, the tool temperature can be determined as an exponential equation with cutting variables and tool nose diameters for the different tool materials. The equations determined in this study show a good correlation for the cutting conditions and can be used for a tool temperature estimation technique. The result indicates that the tool temperature decreases for increasing the tool nose radius in general. Also, nose radius hardly influences on the tool temperature compared with cutting speed, feed rate and depth of cut. This method will be useful for the estimation of tool life and temperature using limited experimental data for given cutting conditions.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1982-1984
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• 1996

In this paper, we have evaluated the physical characteristicsof the Pt/Cr bilayer, fabricated the micro hot plate by using the Pt/Cr bilayer and E-beam evaporated oxide as a passivation layer, and simulated the thermal distribution by using the commercial software FIDAP. From the researches the sheet resistance of Pt/Cr bilayer didn't be affected by the Cr layer thickness. This results was considered due to the Cr-oxide resided at the interface between Pt and Cr layer. After manufacturing the hot plate, we measured its temperature by type k thermo-couple and I.R. thermo-vision system. In those experiments, the emission coefficient( ${\varepsilon}$ ) of the E-beam evaporated oxide was 0.5 and the temperature of centural region was reached about $305\;^{\circ}C$ at 1.3 watts. The temperature simulation obtained by FIDAP commercial package stewed that the temperature of centural region was about $311\;^{\circ}C$ after 5 sec.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.1
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• pp.17-27
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• 2009

Water jet impingement cooling is used to remove heat from high-temperature surfaces such as hot steel plates in the steel manufacturing process (thermo-mechanical cooling process; TMCP). In those processes, uniform cooling is the most critical factor to ensure high strength steel and good quality. In this study, experiments are performed to measure the heat transfer coefficient together with the inverse heat conduction problem (IHCP) analysis for a plate cooled by planar water jet. In the inverse heat transfer analysis, spatial and temporal variations of heat transfer coefficient, with no information regarding its functional form, are determined by employing the conjugate gradient method with an adjoint problem. To estimate the two dimensional distribution of heat transfer coefficient and heat flux for planar waterjet cooling, eight thermo-couple are installed inside the plate. The results show that heat transfer coefficient is approximately uniform in the span-wise direction in the early stage of cooling. In the later stage where the forced-convection effect is important, the heat transfer coefficient becomes larger in the edge region. The surface temperature vs. heat flux characteristics are also investigated for the entire boiling regimes. In addition, the heat transfer rate for the two different plate geometries are compared at the same Reynolds number.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.114-116
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• 2004

The temperature profile control issue in the resistive welder for the electronic parts is discussed. The average current of the welder tip depends on the phase(on-time) of the AC power and the tip temperature maintains or increases/decreases depending on the integral of the current square and heat loss, The basic PID control algorithm with thermo-couple feedback is difficult to track the temperature profile for various parts and optimal gain changes much. So constant gain PID algorithm is not enough to cover various electronic parts welding and a Fuzzy-PID automatic gain tuning algorithm is devised and added to conventional PID algorithm and this hybrid control architecture is implemented and the experimental results are shown.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.465-467
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• 2004

Finite element analysis of welding processes, which entail phase evolution, heat transfer and deformation, is considered in this paper. Attention focuses on numerical implementation of the thermo-elastic-plastic constitutive equation proposed by Leblond et al in consideration of the transformation plasticity. Based upon the multiplicative decomposition of deformation gradient, hyperelastic formulation is employed for efficient numerical integration, and the algorithmic consistent moduli for elastic-plastic deformations including transformation plasticity are obtained in the closed form. The convergence behavior of the present implementation is demonstrated via a couple of numerical examples. Several locking phenomena removed by Solid-shell element.

• The Journal of the Acoustical Society of Korea
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• v.18 no.4
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• pp.3-10
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• 1999

Investigations of temperature differences between both cnds of thermoacoustic exchanger generated by acoustic heat transport have been carried out as a function of the position of TAC(Thermo-Acoustic Couple)[1] in a 68-cm-long duct. Fixed with the electric power at 50W, measurements were compared with the theory changing the frequency from 150Hz to 300Hz with 10Hz step. The frequency-position dependent distribution of temperature difference corresponding to the Q-values was obtained with the numerical simulation. Through this distribution, the optimum position of the thermoacoustic exchanger and the optimum driving frequency can be determined.