• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.06a
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• pp.17-24
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• 1998

This paper deals with the springback characteristics of cold rolled sheet steel through the use of the V-bending process and U-bending one. The influence of material properties on the springback of forming processes was investigated. In the V-bending process there was an optimum bend radius for each combination of parameters which produced minimal springback. In the U-bending process the blank holder force can control the degree of springback. A high blank holding force resulted in a uniform strain distribution and reduced the level of springback.

• Tribology and Lubricants
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• v.11 no.2
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• pp.63-70
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• 1995

The analytical design method of gerotor profile, based on an envelope of a family of curves, is proposed. Analysis to calculate the flow rate and the torque capacity of a gerotor set are presented. The influence of the circular tooth radius and the amount of eccentricity on the configuration of a gerotor has been explored in this paper. The variation of the inlet volume and the fluctuation of the generated torque are also analyzed.

• Steel and Composite Structures
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• v.27 no.4
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• pp.479-493
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• 2018

In this paper nonlocal free vibration analysis of a doubly curved piezoelectric nano shell is studied. First order shear deformation theory and nonlocal elasticity theory is employed to derive governing equations of motion based on Hamilton's principle. The doubly curved piezoelectric nano shell is resting on Pasternak's foundation. A parametric study is presented to investigate the influence of significant parameters such as nonlocal parameter, two radii of curvature, and ratio of radius to thickness on the fundamental frequency of doubly curved piezoelectric nano shell.

• Transactions of Materials Processing
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• v.8 no.1
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• pp.38-46
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• 1999

This paper deals with the shape fixability of press formed parts through the use of a V-bending process and a U-bending one. The influence of material properties on the shape fixability in forming processes was investigated. A V-bending process had on optimum ben radius for each combination of parameters which caused maximum shape fixability. In the U-bending process the blank holder force could control the degree of shape fixability. A ha호 blank holding force resulted in a uniform strain distribution and increased shape fixability.

• Tribology and Lubricants
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• v.15 no.2
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• pp.164-170
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• 1999

Gerotor is widely used as a hydraulic pump or motor, by virtue of its volume changing ability. Performance deterioration of a gerotor hydraulic motor mainly due to the wear come from the contact between inner rotor with trochoidal curve and outer rotor with circular arc profile. This research covers the basic investigation about the contact forces of a gerotor hydraulic motor using analytic method. The influence of the eccentricity and the radius of circular arc teeth on the contact stress was evaluated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.183-186
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• 1998

Axial magnetic field generated by special electrode construction in vacuum interrupters is used to extinguish electric plasma arcs. This investigation by FDM should prove to what extent the magnetic field might influence on the arc expansion. The calculated results show that the stronger magnetic field induced the lesser radius of arc plasma. This study will help to offer good data in design of vacuum interrupters.

• Tribology and Lubricants
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• v.17 no.2
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• pp.97-108
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• 2001

This paper describes the development of performance analysis technique for a leaf-type gas lubricated fail bearing. Stiffness coefficient and frictional damping due to the slip between all contacts of leaves are evaluated for various leaf structures. The fluid film thickness and pressure distribution are computed but it is not considered the elastic deformation by film pressure. The analysis results include the effects that the curvature radius and the length of leaf and the friction coefficient have on the static and dynamic characteristics of the foil bearings.

• Journal of the Korean Ceramic Society
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• v.24 no.4
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• pp.313-320
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• 1987

Fracture toughness of hot pressed cordierite-SiC whisker ceramic composites contained up to 40vol.% SiC whiskers were determined by using the indentation crack length(IC), indentation strengthin-bending(IS), and single-edge notched-beam(SENB) methods. The results were compared to stress intensity factor, KB, at the crack branching boundary measured by using the mirror zone radius (MZ) method. IS method seems to provide a more reasonable estimation of fracture toughness than other methods for these composites.

• Multiscale and Multiphysics Mechanics
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• v.1 no.1
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• pp.65-76
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• 2016

In this study, an influence of local variation of nanoparticulate volume fraction on the homogenized elastic properties is investigated. It is well known that interface effect is dependent on the radius and volume fraction of reinforced nanofillers. However, there is no study on the multiscale modeling and analysis of polymer nanocomposites including polydispersed nanoparticles with consideration of interphase zone, which is dependent on the volume fraction of corresponding nanoparticles. As results of numerical examples, it is confirmed that an influence of local variation of nanoparticulate volume fraction should be considered for non-dilute system such as cluster of nanoparticles. Therefore representative volume element analysis is conducted by considering local variation of nanoparticle volume fraction in order to analyze the practical size of cell including hundreds of nanoparticles. It is expected that this study could be extended to the multiparticulate nanocomposite systems including polydispersed nanoparticles.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.4 no.2
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• pp.46-53
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• 1995

In this study, Wear of a ceramic cutting tool for hardened STD11 steel was investigated. Under the finish machining condition. DOC notch wear of a ceramic cutting tool was mostly occurred earlier than flank and crater wear were proceeded. The relations of DOC notch wear, which was characteristically produced at the beginning of cutting. to cutting speed, feed, depth of cut, and nose radius of a ceramic cutting tool were examined. Effective approach angle, which is a function of cutting conditions, and boundary area were suggested, and then the influence of those was investigated, The following conclusions were obtained: (1)as cutting speed was increasing. DOC notch wear was decreasing (2) the cutting condition that magnitude of slendermess ratio was made small, was favorable for DOC notch wear, (3) as depth of cut was smaller, the influence of feed on DOC notch wear was also smaller, (4) DOC notch wear was mainly influenced by effective approach angle, but by boundary area in the range of low feed.