• Journal of Energy Engineering
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• v.23 no.3
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• pp.221-230
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• 2014

Simplified finite element model of spark ignition (SI) engine to analyse combustion heat transfer is presented. The model was discredited with 3D thermal elements of global length 5 mm. The fuel type is petrol. Internal nodal temperature of cylinder body is defined as 21000C to represent occurrence of gasoline combustion. Material information and isotropic material properties are taken from published report. The heat transfer analysis is done for the instant of combustion. The model is validated by comparing the computed maximum temperature at the piston surface with the published result. The computed temperature gradient at the crucial parts are plotted and discussed. It has been found that the critical top surface suffered from thermal and the materials used to construct the engine parts strongly influenced the temperature distribution in the engine. The model is capable to analyze heat transfer in the engine reasonably and efficiently.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.4
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• pp.20-28
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• 2008

Missile operating at supersonic conditions experiences considerable high temperature environments that is caused by aerodynamic heating as a result of the temperature gradient through boundary layer that surrounds it. This is one of important problems to the designer due to temperature limitation of structural materials. Because prediction of aerodynamic heating on missile needs unsteady calculation according to a flight trajectory, approximate method approach is efficient at design stage. In this paper, improved aerodynamic heating analysis scheme is introduced, which calculates heat flow and temperature by simple pressure field prediction on a missile body and fin. The prediction results are compared with measured data and MINIVER codes results.

• Journal of Korea Foundry Society
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• v.11 no.1
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• pp.79-84
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• 1991

The process of solidification of metal is accompanied by liquid-solid change and known as Stefan's heat conduction problem on the moving boundary. In this study the temperature distribution in ingot and metallic mould during casting was analyzed by the two dimensional heat conduction theory. The transient temperature distribution was numerically calculated using a finite element method on the nodal point of mesh screen representing ingot and mould cross section. The theory was applied on the casting of aluminum(purity ; 99%) in flat ingot mould of GC25. The analysis will make it possible to calculate an optimum mould shape of which temperature gradient becomes minimum.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.1
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• pp.50-55
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• 1986

Characteristics of the flow and heat transfer in a channel of 37 rods are investigated numerically. The flow is taken to be a fully developed incompressible laminar flow and it has an uniform temperature profile at the inlet and flows down through the channel of constant wall temperature. A boundary-fitted coordinate system is used for the complex geometry. Calculation is initiated by calculating the developed flow profile and then proceeds to temperature development. Through the calculation the details of the flow and temperature distribution characteristics are found, and discussion is made on the mechanism of the transport phenomena in the complex geometry in terms of wall shear stress distribution, non-dimensionalized velocity, friction factor, Nusselt number distribution, Reynolds number, and porosity. Also the effects of the eccentricity in rod configuration are analyzed and its importance is emphasized.

• Nuclear Engineering and Technology
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• v.43 no.1
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• pp.1-6
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• 2011

The behavior of the non-equilibrium grain boundary segregation of boron in low carbon steel was studied through a particle tracking autoradiography. The behavior of the non-equilibrium grain boundary segregation of boron during continuous cooling was compared with the isothermal kinetics of the non-equilibrium grain boundary segregation of boron at the holding temperature using an effective time method. On the basis of the experiments, the cooling rate dependence of the non-equilibrium segregation of boron was explained using the time dependence of the non-equilibrium segregation of boron in low carbon steel. The experimental observations for the cooling rate dependence of the grain boundary segregation of boron are in good agreement with the time dependence of the grain boundary segregation of boron. The mechanisms of the non-equilibrium segregation of boron during cooling in low carbon steel are also discussed.

• Korean Journal of Metals and Materials
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• v.48 no.11
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• pp.1021-1027
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• 2010

The charpy impact property was lower at the surface and middle regions than that at the root region in metal welded by Tandem EGW of 82 mm thick EH40-TM steel plates. Temperature distribution in the weld sample and the heating/cooling temperature throughout the various regions in the weld metal were estimated by the commercial weld simulation program SYSWELD. The microstructure of the weld metal consisted of acicular ferrite and grain boundary ferrite. Grain boundary ferrite in the acicular ferrite matrix was found more in the surface and middle regions than in the root region, and the acicular ferrite was also coarser in the surface and middle regions where the impact toughness was lower and the input temperature was higher. Our results indicated that the impact toughness property was related to the microstructure morphology, the distribution of grain boundary ferrite, and the acicular ferrite.

• Steel and Composite Structures
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• v.12 no.2
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• pp.129-147
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• 2012

In this paper, the thermal buckling analysis of rectangular composite laminated plates is investigated using the Differential Quadrature (DQ) method. The composite plate is subjected to a uniform temperature distribution and arbitrary boundary conditions. The analysis takes place in two stages. First, pre-buckling forces due to a temperature rise are determined by using a membrane solution. In the second stage, the critical temperature is predicted based on the first-order shear deformation theory. To verify the accuracy of the method, several case studies were used and the numerical results were compared with those of other published literatures. Moreover, the effects of several parameters such as aspect ratio, fiber orientation, modulus ratio, and various boundary conditions on the critical temperature were examined. The results confirm the efficiency and accuracy of the DQ method in dealing with this class of engineering problems.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.3 s.246
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• pp.270-277
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• 2006

Inverse radiation problems were solved for estimating boundary temperature distribution in a way of function estimation approach in an axisymmetric absorbing, emitting and scattering medium, given the measured radiative data. In order to reduce the computational time fur the calculation of sensitivity matrix, automatic differentiation and Broyden combined method were adopted, and their computational precision and efficiency were compared with the result obtained by finite difference approximation.. In inverse analysis, the effects of the precision of sensitivity matrix, the number of measurement points and measurement error on the estimation accuracy had been inspected using quasi-Newton method as an inverse method. Inverse solutions were validated with the result acquired by additional inverse methods of conjugate-gradient method or Levenberg-Marquardt method.

• Structural Engineering and Mechanics
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• v.65 no.4
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• pp.389-400
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• 2018

An exact solution for the title problem was obtained in closed-form fashion considering general boundary conditions. The expressions of moment, shear and shear coefficient (or shear factor) of cross section under the effect of arbitrary temperature distribution were first derived. In view of these relationships, the differential equations of Timoshenko beam under the effect of temperature were obtained and solved. Second, the characteristic equations of Timoshenko beam carrying several spring-mass systems under the effect of temperature were derived based on the continuity and force equilibrium conditions at attaching points. Then, the correctness of proposed method was demonstrated by a Timoshenko laboratory beam and several finite element models. Finally, the influence law of different temperature distribution modes and parameters of spring-mass system on the modal characteristics of Timoshenko beam had been studied, respectively.

• Particle and aerosol research
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• v.14 no.2
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• pp.35-40
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• 2018

Vertical particle size distribution, total particle concentration, wind velocity, temperature and humidity measurement was performed with a drone. The drone was equipped with a wind sensor, house-made optical particle count(Hy-OPC), condensation particle counter(Hy-CPC), GPS, Temperature, Relative Humidity, Pressure and communication system. Base on the wind velocity and the particle size vertical distribution measurement with drone, the particle mass flux was calculated. The vertical particle distribution showed that the particle number concentration was very strongly correlated with the relative humidity.