• Design & Manufacturing
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• v.8 no.2
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• pp.30-36
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• 2014

In this study, surface deformation patterns have been investigated by the rigid-plastic finite element method for friction factor test in solid cylinder compression process. AA1100 and AA6063 aluminum alloys, which show different work hardening characteristics respectively, have been adopted as model materials used for analysis. The main objective of this study is to provide the deformation mechanics in detail in solid cylinder compression process, especially at the die/workpiece interface that is closely related with the frictional conditions. For this reason, solid cylinder compression process has been numerically analyzed. The surface flow patterns at the contact boundary have been analyzed in terms of surface expansion, surface expansion velocity, pressure distributions exerted on the die surface along the die surface. By defining bulge factor, barreling phenomenon also have been examined with calibration curves to verify their effects on the surface flow pattern that is important for evaluating the frictional condition at the interface.

• Agricultural and Biosystems Engineering
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• v.6 no.1
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• pp.22-26
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• 2005

A wind-heat generation system was developed and the system consisted of an electric motor, a heat generation drum, a heat exchanger, two circulation pumps and a water storage tank. The heat generation drum is an essential element determining performance of the system. Frictional heat was generated by rotation of a rotor in the drum filled with a working fluid, and the heat stored in the fluid was used to increase water temperature through the heat exchanger. Effects of some factors such as rotor shape, kind and amount of working fluid, rotor rpm and water flow rate in the heat exchanger, affecting the system performance were investigated. Amounts of heat generated were varied, ranging from 126,000 to 32,760 kJ/hr, depending on combination of the factors. Statistical analysis using GLM procedure revealed that the most influential factor to decide the system performance was amount of the fluid in the drum. Experiments showed that the faster the speed of the rotor, the greater heat was obtained. The greatest efficiency of the heat generation system, electric power consumption rate vs gained heat amount of water, was about 70%. Though the heat amount was not enough for plant bed heating of a 0.1-ha greenhouse, the system would be promising if some supplementary heat source such as air- water heat pump is added.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1044-1048
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• 2006

Nuclear power generation is very dangerous in occasion that skirt of structure by earthquake although it is high effective generation that can make a lot of energies with few raw material. when design, it must consider a lot of problems caused by an earthquake. The seismic analysis of the structure has been great concern in the engineering society with an effort to reduce the severe damages from an earthquake. So the earthquake resistant design is one of the crucial design procedures of a gate valve used in nuclear power generation. The gate valve which has the contact area between stem and bellows. Because of the contact area. The gate valve should be given high stress and frictional wear. In this thesis, Considering the gate valve which has some contact distance between stem and bellows. The gate valve which has some contact distance is analyzed by a commercial FEM code of Ansys and Then compared to the gate valve behavior which doesn't have contact distance.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.383-384
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• 2002

Frictional sound is observed in great many practical systems, but its generation mechanism is still unknown Model systems are best suited for research on the fundamental mechanisms, but results cannot be easily applied to real systems, because each system has different sound radiation properties. At present, there is no easy method for evaluation of these properties. We propose to describe the sound radiation property of a tribo-system by the relationship between friction-induced sound power and the friction-induced vibration velocity of the contact element. It was found that the sound power of a tribo-system is linearly proportional to the mean-square velocity of the sliding element by a constant coefficient having the dimension of mass flow rate (kg/s).

• Design & Manufacturing
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• v.6 no.1
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• pp.45-51
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• 2012

The main goal of this paper is to establish an interference tolerance for determining optimal amount of clearance in the shaft-bearing system supported by radial ball bearings. The 2-D frictional contact model was employed for the FE analysis between the shaft and the inner raceway. Several examples were simulated using different material properties for the solid shaft. Efforts were focused on the deformation applied in the radial direction to select suitable bearings. The analysis results showed that the initial axial preload applied on the bearings plays a significant role to reduce bearing fatigue life. The proposed design parameters obtained by numerical simulations can approximately predict a rate of bearing life reduction as a function of shaft diameter ratio. This analysis can also be used to calculate the optimal initial radial clearance in order to obtain a shaft-bearing system design for high accuracy and long life.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.143-150
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• 2002

The characteristics of rubber cup seal is highly nonlinear due to the nature of the material's non-linearity and large deformation with frictional contact. And the performance of sealing in master cylinders of automobile is one of the most important factors which affects the safety of drivers. The effects of various shape of the primary cup seal in clutch master cylinder was investigated to reduce oil leakage and to obtain a long reliable life. Deformation and distribution of stresses on the primary cup seal against hydraulic oil pressure were analyzed with changing design parameters such as depth and radius in cup-seal. The obtained results indicate that the depth of cup seal plays a major role on deformation resulting in the sealing force to the wall of clutch master cylinder.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.343-346
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• 2004

In recent years, various forms of indentation testing have been increasingly used to determine the material properties of specimens. This technique, particularly the nano-indentation method , has been extended to the testing of coating systems in order to calculate the individual properties of the thin coatings and the substrates. However, the interpretation of the test data to achieve this is complex and continues to be a widely studied subject. Based on the finite element method of coated surfaces indented by a Berkovich diamond tip, this paper describes methods for combining FEM and experimental indentation testing to determine coating modulus and hardness independent of substrate effects. Using this proposed methodology, testing and FEM to measure coefficients of friction of sheet steel for outer panel were studied.

• Transactions on Electrical and Electronic Materials
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• v.10 no.5
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• pp.156-160
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• 2009

In an ultrasonic motor, a piezoelectric ceramic material forms the active element which vibrates the stator, thus initiating the rotational motion. In the operation of ultrasonic motors, many factors exist that can affect the resonance characteristics of the piezoelectric ceramic component. For examples, these factors are the bonding conditions with the piezoelectric element, the magnitude of the input voltage, the normal force in the frictional drive and the emission of heat due to vibration and friction etc. Therefore, it is important to research properly the inclination for variation of piezoelectric ceramics in the circumstance where complex elements are involved. In this paper, we focus on the analysis of the resonance characteristics of an ultrasonic motor as a function of the magnitude of the input voltage and the normal force.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10b
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• pp.22-25
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• 2003

The forming limits are studied for cold upsetting of high strength aluminium alloy in the present paper. Different geometry ratio and frictional conditions are investigated in the forgeability test to evaluate the forming limits and also to obtain the various strain paths. The critical fracture value can be obtained by integrating along the strain path till free surface crack initiation. To predict the damage evolution of cold upsetting, the computer-aided evaluation of forming limits is obtained by using the finite-element software DEFORM-3D and the modified Cockcroft-Latham criterion. The predicted theoretical limit strains agree quite well with the experimental results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.804-807
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• 1997

Recently equal-channel angular pressing (ECAP) has been employed to produce ultra-fine grain size materials. In this paper pure-Zirconium is considered due to its applicability to nuclear reactors. Among many process parameters of ECAP frictional effect on the plastic deformation of die has been investigated. The back pressure effect due to friction increases the stress level of die especially at the crossing area of channels, which may result in plastic deformation of die. The finite element method has been employed to investigate this issue.