• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.4
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• pp.731-742
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• 1998

Bolted opening structures is widely applied for class 1 machinery of nuclear plant with strict design requirement. As the shape of the bolted opening structure is non-axisymmetric due to the existence of stud bolts although it is almost axi-symmetric, 3D analysis is required to satisfy such kind of design requirements. Because as much as possible trial computations are need to get an optimal design condition in the limited period of basic design, an easy and fast analysis tool is useful in the design stage. In the paper, a transformation technique of non-axisymmetric problem into quasi-axisymmetric has been proposed based on the general purpose commercial code ANSYS. Both the pre-processor which incorporates the technique and prepares data and post-processor which prepares arranged results from the huge output of commercial code have been developed to help the design engineers.

• Composites Research
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• v.16 no.4
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• pp.59-65
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• 2003

FEM analysis of the smart skin structure, and application of the sandwich structures investigated. The honeycomb manufactures only provide stillness of thickness direction and transverse shear modulus. Although these are dominant mechanical properties. the other mechanical properties are needed in FEM analysis. Hence, this work shows procedures of obtaining those mechanical properties. Honeycomb material was assumed to be ar, isotropic material and properties are estimated by its dominant honeycomb properties. The other honeycomb properties are then obtained by mechanical properties of Nomex. Buckling test and three point bending test were simulated by ABAQUS. Both the shell and solid element models were used. The results were compared with experimental results and analytical approaches. They showed good agreements. This study shows a guideline of FEM analysis of smart skin structure using commercial a FEM package.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.7
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• pp.2067-2077
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• 1996

In adaptive finite element analysis, r- and h-methods are generally used on the basis of a discretization error estimator. In this paper, an rh-method is proposed as a new adaptive method which can improve the adaptivity performance by using both of them. This suggested rh-method moves nodal coordinates of initially given model to adjust element discretization errors and thereafter performes the h-method tdo obtain the specified accuracy of finite element solutions. Numerical experiments for various plane problems were performed using 4-noded isoparametric quadrilateral elements. As a result, the rh-method has been shown to be an accurate and efficient adaptive analysis method to obtain as improved solution.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.9
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• pp.888-891
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• 2011

This paper presents development of flow control valve using MR fluid. Generally, since the apparent viscosity of MR fluids is adjusted by applying magnetic fields, the MR valves can control high level fluid power without any mechanical moving parts. In this paper, flow control valve using MR fluid on the behavior of the magnetic field influence on the numerical analysis of more accurate electromagnetic parameters were obtained, even if when magnetic field apply inside of surrounding MR fluid from electromagnet, more realistic designing way analysis of characteristic of whole magnetic field distribution is suggested by surrounding magnetic material. Also, comparison of flow rate inlet and outlet, behavior of MR fluid in experiments proposed. A new type of flow control valve using MR fluid is proposed by analysis of behavior of MR fluid in experiments.

• Journal of Mechanical Science and Technology
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• v.20 no.7
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• pp.1089-1097
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• 2006

The market demand of display devices is drastically increasing in the information technology age. The research on OLED (Organic Light Emitting Diodes) display with the luminescence in itself is being more paid attention than LCD (Liquid Crystal display) with the light source from the back. The vapor deposition process is most essential in manufacturing OLED display. The temperature distribution of the linear cell in this process is closely related to securing the uniformity of organic materials on the substrate. This work analyzed the temperature distribution depending on the intervals between the crucible and the heating band as well as on the amount of the heat flux from the heating band. Moreover, the roles of the water jacket and the configuration of the cover within the linear cell were examined through the temperature analysis for six configurations of the linear cell. Under the above temperature analysis, the variations in the intervals and the amount of the heat flux were considered to have an effect on building the uniform temperature distribution within the crucible. It is predicted that the water jacket and the adequate configuration of the cover will prevent the blowout and clogging phenomena, respectively. The results can be used as the fundamental data for designing the optimal linear cell.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.7-12
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• 2010

In this work, optimization analysis has been accomplished to find important process factors for realization of vertical wall around holes punched by the punchless piercing process. Taguchi method was used for optimization analysis. Lemaitre damage theory, one of the ductile fracture models, was also adopted to simulate numerically formation of vertical wall. From the results of analysis the most influencing factor that affects the vertical wall has been revealed to be 'Corner Radius of Die'.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.2
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• pp.209-217
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• 2015

Generally welding is one of the most important processes to have a strong influence on the quality and productivity from a manufacture-based industry such as shipbuilding, automotive and machinery. The GMA(Gas Metal Arc) welding process involves large number of interdependent welding parameters which may affect product quality, productivity and cost effectiveness. To solve such problems, mathematical models are required to select the welding parameters for GMA welding process. In this study, the GMA welding process was studied using the information generated during the welding. The statistical analysis of a generalized regression approach was conducted by the following three methods: Firstly using the mathematical model (linear regression, 2nd regression); Secondly GA(Genetic Algorithm) with intelligent models; And finally using response surface analysis of models to develop the relationships between welding parameters and bead width as welding quality.

• Journal of the Korean Ceramic Society
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• v.45 no.4
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• pp.238-244
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• 2008

Modeling and FEM analysis on Boron Nitride and/or Pyrolytic Carbon coating layers on SiC fibers under indentation contact loadings are investigated. Especially this study attempts to model the mechanical behavior of the SiC fibers with and without coatings. Tyranno S grade and Tyranno LoxM grade of SiC are selected for fiber and Boron Nitride and/or Pyrolytic Carbon as coating material. The modeling is performed by SiC fiber without coating layer, which includs single(BN or PyC) and double(BN-PyC or PyC-BN) coating layer. And then the analysis is performed by changing a type of coating layer, a type of fiber and coating sequence. In this study, the concepts of modeling and analysis techniques for optimum design of BN and PyC coating process on SiC fiber are shown. Results show that stresses are reduced when indentation contact loading applies on the material having lower elastic modulus.

• The Journal of Korea Robotics Society
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• v.11 no.2
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• pp.73-82
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• 2016

This paper focuses on the vibration analysis of planar cable-driven parallel robots on their configurations. Despite of many advantages of the cable robots, elasticity of the cables may cause the vibration at the existence of external disturbance, resulting in deterioration of positioning accuracy. According to the vibration theory, having high first order natural frequency can prevent resonance with low frequency disturbance from the surrounding environment. A series of simulations showed that choosing frame / end-effector shape and cable connection method affects robots' natural frequency. For the precise simulation, the cables are modeled as linear springs and axial vibration of cables is mainly considered. Aspect ratios of the frame and end-effector are defined as non-dimensional parameters while their areas are fixed. It was shown that vibration analysis guides to design a planar cable robot in terms of high capacity to reduce vibration.

• Design & Manufacturing
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• v.14 no.4
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• pp.58-64
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• 2020

Lately, the development of the semiconductor industry has led to the miniaturization of electronic devices. Therefore, semiconductor wafers of very thin thickness that can be used in Multi-Chip Packages are required. There is active research on the backgrinding process to reduce the thickness of the wafer. The backgrinding process polishes the backside of the wafer, reducing the thickness of the wafer to tens of ㎛. The equipment that performs the backgrinding process requires ultra-precision. Currently, there is no full auto backgrinding equipment in Korea. Therefore, in this study, ultra-precision backgrinding equipment was designed. In addition, finite element analysis was conducted to verify the equipment design validity. The deflection and structural stability of the backgrinding equipment were analyzed using finite element analysis.