• Tribology and Lubricants
• /
• 제35권3호
• /
• pp.158-168
• /
• 2019

This paper presents the investigation of two types of rotordynamic modeling issues for 2.2 kW-class, rated speed of 1,800 rpm, squirrel-cage type induction motors. These issues include the lamination structure of rotor cores, and the radial clearance of ball bearings that support the shaft of the motor. Firstly, we focus on identifying the effects of rotor core lamination on the rotordynamic analysis via a 2D prediction model. The influence of lamination is considered as the change in the elastic modulus of the rotor core, which is determined by a modification factor ranging from 0 to 1.0. The analysis results show that the unbalanced response of the rotor-bearing system significantly varies depending on the value of the modification factor. Through modal testing of the system, the modification factor of 0.079 is proven to be appropriate to consider the effects of lamination. Next, we investigate the influence of ball bearing clearance on the rotordynamic analysis by establishing a bearing analysis model based on Hertz's contact theory. The analysis results indicate that negative clearance greatly changes the bearing static behavior. Rotordynamic analysis using predicted bearing stiffness with various clearances from -0.005 mm to 0.010 mm reveals that variations in clearance result in a slight difference in the displacement of the system up to 18.18. Thus, considering lamination in rotordynamic analysis is necessary as it can cause serious analysis errors in unbalanced response. However, considering the effect of the bearing clearance is optional because of its relatively weak impact.

• 대한건축학회논문집:구조계
• /
• 제35권6호
• /
• pp.121-128
• /
• 2019

There is a big move to build zero-energy buildings in the form of passive houses that reduce energy waste worldwide. Korea has set a goal of reducing its greenhouse gas emissions by 37% by 2030 through the activation of green buildings, such as strengthening the energy levels of new buildings and improving the energy efficiency of existing buildings. The use of insulation with high insulation performance is one of the key technologies to realize this, and vacuum insulation is the next generation insulation that blocks the energy flow of the building. In this study, we measured the bonding structure of dry and wet processing glass fiber core materials and compared the insulation performance of vacuum insulation panel. In addition, the insulation performance of vacuum insulation panel was measured according to the thickness of the laminated core. It can be confirmed that the lamination structure of the core and the lamination thickness are important factors for the heat insulating performance of the vacuum insulating panel.

• 한국초전도ㆍ저온공학회논문지
• /
• 제18권3호
• /
• pp.6-9
• /
• 2016

The enhancement of mechanical properties of coated conductor (CC) tapes in practical application are usually achieved by reinforcing through lamination or electroplating metal layers on either sides of the CC tape. Mechanical or electromechanical properties of the CC tapes have been largely affected by the lamination structure under various loading modes such as tension, bending or even cyclic. In this study, the influence of brass laminate volume fraction on electromechanical properties of RCE-DR processed Gadolinium-barium-copper-oxide (GdBCO) CC tapes was investigated. The samples used were composed of single-side and both-side laminate of brass layer to the Cu-stabilized CC tape and their $I_c$ behaviors were compared to those of the Cu-stabilized CC tape without external lamination. The stress/strain dependences of $I_c$ in laminated CC tapes under uniaxial tension were analyzed and the irreversible stress/strain limits were determined. As a result, the increase of brass laminate volume fraction initially increased the irreversible strain limit and became gradual. The corresponding irreversible stress limit, however, showed no difference even though the brass laminate volume fraction increased to 3.4. But the irreversible load limit linearly increased with the brass laminate volume fraction.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제53권10호
• /
• pp.546-550
• /
• 2004

Two fabrication approaches are proposed to planarize the sacrificial layer over hollow structures. One is the photoresist filling method that makes use of photolithography, thermal curing and plasma ashing. The other is the lamination method that is applying pressure and temperature to the organic film over the hollow structures. The fabrication results are compared with those of CMP process. Trenches and cavities with various dimensions have been made for the porposed process. Upon measuring the planarization levels, they are dependent on planarization methods and the geometrical size of hollow structures. The photoresist filling method is so strongly dependent on the width and depth of trenches that we have problems to use it for large dimensional trenches. To the contrary, the flatness of sacrificial layer over the trenches was found to be almost independent of trench dimensions for the lamination method. A CMP process shows the most excellent results, but the fabrication is complicated and the access to it is not so easy. It is important to choose the proper planarization method by considering the required flatness levels, materials to be planarized, and connection between the planarization step and the previous or the following process of it.

• Transactions on Electrical and Electronic Materials
• /
• 제12권1호
• /
• pp.32-34
• /
• 2011

A zero-shrinkage sintering process in which the shrinkage of the x-y axis is controlled to be zero is in great demand due to the high integration trend in ceramic modules. Among the zero-shrinkage sintering processes available, the glass infiltration method proposed in the preliminary study with an $Al_2O_3/Glass/Al_2O_3$ structure is one promising method. However, problems exist in regard to the glass infiltration method, including partially incomplete joining between $Al_2O_3$ and glass layers due to the precipitate of Ti-Pb rich phase during the sintering process. Therefore, we wish to solve the de-lamination problems and suggest a mechanism for delamination and the solutions in the zero-shrinkage low temperature co-fired ceramic (LTCC) layers. The de-lamination problems diminished using the Pb-BSi-O glass without $TiO_2$ in Pb-B-Ti-Si-O glass and produced a very dense zero-shrinkage LTCC.

• 한국전기전자재료학회논문지
• /
• 제35권3호
• /
• pp.281-291
• /
• 2022

Global warming is accelerating due to the use of fossil fuels that have been used continuously for centuries. Now, humankind recognizes its seriousness, and is conducting research on searching for eco-friendly and sustainable energy. In the field of solar energy, which is a kind of eco-friendly and sustainable, many studies are being conducted to enhance the output performance of the module. In this study, the output improvement for the shingled module structure was studied. In order to improve the output performance of the module, the thickness of the encapsulant was increased, and the lamination process conditions have been improved accordingly. After that, the crosslinking rate was analyzed, and the suitability of the lamination process conditions was judged using this. In addition, a peeling test was conducted to analyze the correlation between the adhesion of the encapsulant and the output performance of the module. Finally, the optimization for the encapsulant material and the lamination process conditions for high-power shingled modules was established, and accordingly, the market share of high-power shingled modules in the solar module market can be expected to rise.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
• /
• pp.228-233
• /
• 2001

Satellite system experiences severe mechanical loads during the launch period. Therefore, positive margin of safety of the satellite system must be demonstrated for every possible mechanical loading condition during the launch period. This paper presents modal and stress analysis result due to quasi-static loads for the satellite antenna system. The failure tendency for the sandwich construction of the satellite antenna system has been studied with various lamination angles of unidirectional prepreg.

• International Journal of Aeronautical and Space Sciences
• /
• 제14권4호
• /
• pp.334-340
• /
• 2013

This paper deals with the optimization of blade stiffened composite panels. The main objective of the research is to make response surfaces for the constraints. The response surface for warping thermal deformation was previously made for a fixed dimension composite structure. In this study, the dimensions of the blade stiffener were treated as design variables. This meant that a new response surface technique was required for the constraints. For the response surfaces, the lamination parameters, linear thermal expansions and dimensions of the structures were used as variables. A genetic algorithm was adopted as an optimizer, and an optimal result, which satisfied two constraints, was obtained. As a result, a new response surface was obtained, for predicting warping thermal deformation.

• Steel and Composite Structures
• /
• 제29권4호
• /
• pp.493-508
• /
• 2018

Free vibration analysis of super-elliptical composite thin plates was investigated. Plate is formed by symmetrical quasi-isotropic laminates. Rayleigh-Ritz method was used for parametric analysis based on the governing differential equations of Classical Laminated Plate Theory (CLPT). Simply supported and clamped boundary conditions at the periphery of plates were considered. Parametric study was performed for the effect of different lamination type, aspect ratio, thickness and super-elliptical power on natural frequencies. Convergence study and validation of isotropic case were achieved. A number of design parameters like different dimensions, structure systems, panel sizes, panel thicknesses, lamination sequences, boundary conditions and loading conditions must be considered in the production of composite ships. The number of possible combinations practically may be so high that a parametric study should be carried out in order to determine the optimum design parameters rapidly during the preliminary design stage. The use of Rayleigh-Ritz method could make this parametric study possible. Thereby it might be decreasing the consumption of time, material and labor. Certain results for some different super-elliptical powers presented in tabulated form in Appendix for designers as well.

• 한국기계가공학회지
• /
• 제18권1호
• /
• pp.59-64
• /
• 2019

In recent years, the HP-CRTM method, which has the ability to produce carbon fiber-reinforce plastic composites at high speeds, has come into the spotlight in the automotive parts industry, which demands high productivity. Multi-axial carbon fabric, an intermediate material used in this HP-CRTM molding process, consists of layered fibers without crimp, which makes it better in terms of tensile and shear strength than the original woven fabrics. The NCF (non-crimp fabric) can form the layers of the carbon fiber, which have different longitudinal and lateral directions, and ${\pm}{\theta}$ degrees, depending on the product's properties. In this research, preforms were made with carbon fibers of ${\pm}45^{\circ}$ and $0/90^{\circ}$, which were lamination structures under seven different conditions, in order to create the optimal laminated structure for automobile reinforcement center floor tunnels. Carbon fiber composites were created using each of the seven differently laminated preforms, and polyurethane was used as the base material. The specimens were manufactured in accordance with the ASTM D3039 standards, and the effect of the NCF lamination structure on the mechanical properties was confirmed by a tensile test.