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NOMENCLATUREC P =specific heat of ABS sheet, J/kg.K H=thickness of total sheets, m h=heat transfer coefficient, W/m 2 .K k=thermal conductivity of ABS, 0.174 W/m.K k eq =thermal conductance, W/m.K L=half of the total thickness, m N=total number of sheets q in =inputted heat flux, W/m 2 R c =contact resistance, m․ K/W T a =average temperature, K T c =center temperature, K T s =surface temperature, K T 0 =initial temperature, K T ∞ =environmental temperature, K t=time, s t h =heating time, s ρ=density of ABS sheet, 1050 kg m -3 α=thermal diffusivity of ABS, m 2 /s η n =eigen valueObtaining a uniform thickness of the final product using thermoforming is difficult, and the thickness distribution depends strongly on the distribution of the sheet temperature. In this paper, the time-dependent temperature distribution of the total sheets in the storing stage was studied because the temperature after the storing stage is the initial temperature of the heating process. An analytic solution for simulating the storing stage was derived. Using the solved analytic solution, the time-dependent temperature distribution of the total sheets was found out under the condition of assuming that the temperature-dependent specific heat of the ABS sheets was a certain constant value. Finally, the control method for a successful thermoforming using the heater power or heating time was researched in order to improve the quality of the final products. The results show that the satisfied temperature distribution can be obtained by adjusting the heater power or heating time. The method for analysis in this study will be used to improve the quality of the final products.

A new method using thermal analysis database and optimization technique has been developed to substitute the original method what was based on trial and error. First, an original vacuum furnace was manufactured according to experiences. Modified baseline vacuum furnace which can be used in high temperature was produced from the original one by using experimental data and experiences. The results in 2 different conditions of nearly vacuum and argon ambient gas were investigated in order to define the worse but necessary condition between them. By comparing the analysis results with experimental results, the unknown thermal conductivity of insulator in high temperature has been found out. The calculated thermal conductivity of insulator has been applied to the process of thermal analysis database constructing under the condition of argon ambient gas which is the worse but necessary condition. In order to check the accuracy of constructed thermal analysis database, the interpolated results using constructed thermal analysis database have been compared with computational results. Finally, optimization study has been carried out to design an energy efficient, high temperature vacuum furnace which can fully satisfy user's design requirements by using the new method. Feasible optimal design has been obtained as a final product. With negligible computational cost, a high temperature vacuum furnace which has 31.9% reduction in the total heat was designed by using the new developed method.

Composite materials are increasingly used in wind blade because of their superior mechanical properties such as high strength-to-weight and stiffness-to-weight ratio. This paper presents vibration and damping analysis of fiberreinforced composite wind turbine blade with viscoelastic damping treatment. The finite element method based on full layerwise displacement theory was employed to analyze the damping, natural frequency, and modal loss factor of composite shell structure. The lamination angle was considered in mathematical modeling. The curved geometry, transverse shear, and normal strains were exactly considered in present layerwise shell model, which can depict the zig-zag in-plane and out-of-plane displacements. The frequency response functions of curved composite shell structure and wind blade were calculated. The results show that the damping ratio of viscoelastic layer is found to be very sensitive to determination of magnitude of composite structures. The frequency response functions with variety of thickness of damping layer were investigated. Moreover, the natural frequency, modal loss factor, and mode shapes of composite fiber reinforced wind blade with viscoelastic damping control were calculated.

A new method using the response surface method and optimization technique has been developed instead of the original method based on trial and error. In order to construct a response surface, thermal analysis was performed under the condition of using the calculated thermal conductivity of the insulator in a previous study. In order to set up the response surface, the D-Optimal method was used in the process of selecting experimental points. Using a weighting factor, an optimization study was carried out under the condition of satisfying user requirements. Finally, the merits and drawbacks of the new method were described by comparing with the optimal design method based on the thermal analysis database which was developed in a previous study. The optimal results show that the developed method can be used to design an energy efficient, low manufacturing cost, high temperature vacuum furnace with avoiding unnecessary iterative manufacturing, and anticipating the performance before manufacturing.

This paper has applied the constrained viscoelastic layer damping treatments to a cylindrical aluminum shell using layerwise displacement theory. The transverse shear, the normal strains, and the curved geometry are exactly taken into account in the present layerwise shell model, which can depict the zig-zag in-plane and out-of-plane displacements. The damped natural frequencies, modal loss factors, and frequency response functions of cylindrical viscoelastic aluminum shells are compared with those of the base thick aluminum panel without a viscoelastic layer. The thickness and damping ratio of the viscoelastic damping layer, the curvature of proposed cylindrical aluminum structure, and placement of damping layer of the aluminum panel were investigated using frequency response function. The presented results show that the sandwiched viscoelastic damping layer can effectively suppress vibration of cylindrical aluminum structure.

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