• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.731-732
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• 2011

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.2
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• pp.523-536
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• 1991

This dissertation analyzes the running mechanism of flexible and thin tape above rotating head through the numerical simulation and the experiment. The scope of analysis is confined to the phenomena of two dimensional elasto hydrodynamic lubrication between the protruded bump on a rotating cylinder and the running tape. This model is based on the elastic deformation equation of plate and shell and Reynolds equation. Finite difference method is employed as a numerical technique to calculate (1) the distribution of pressure between the running tape and rotating bump and (2) the vertical deformation of elastic thin tape over he rotating bump under hydrodynamic pressure. In numerical analyses, the effects of bump size on flying characteristics of the tape were evaluated and examined considering the influence of tension and stiffness of tape.

• Bulletin of the Korean Mathematical Society
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• v.50 no.2
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• pp.559-581
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• 2013

This paper is motivated by a 2001 paper of Choie and Kim and a 2006 paper of Bump and Choie. The paper of Choie and Kim extends an earlier result of Bol for elliptic modular forms to the setting of Siegel and Jacobi forms. The paper of Bump and Choie provides a representation theoretic interpretation of the phenomenon, and shows how a natural generalization of Choie and Kim's result on Siegel modular forms follows from a natural conjecture regarding ($g$, K)-modules. In this paper, it is shown that the conjecture of Bump and Choie follows from work of Boe. A second proof which is along the lines of the proof given by Bump and Choie in the genus 2 case is also included, as is a similar treatment of the result of Choie and Kim on Jacobi forms.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.91-96
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• 2001

When it is considered that many vehicle rides on the road and ride quality is an important method to evaluate vehicle performance with handling, running-over-bump manoeuvre may be suitable for testing ride quality. In this paper, a computed model has roughly steering system and lumped mass, connected by joint each rigid body, and suspension that has beam elements and has shock absorber as force element to represent nonlinear characteristics. A computer simulations for passing over a bump were made with two velocities. One side of vehicle passed over bump in due consideration of driver's habit that driver is subject to avoid a bad ride quality. On simulation, vertical acceleration, pitch angle and roll angle were measured at the mass center of chassis each case.

• Journal of Astronomy and Space Sciences
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• v.23 no.2
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• pp.91-96
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• 2006

We use near-infrared observations of eight selected Galactic globular clusters to estimate their distances by comparing the observed and theoretically predicted K magnitudes of the red giant branch bumps and tips. The K magnitude levels of the RGB bump and tip have been measured from the luminosity function of the selected RGB stars in the clusters. Theoretical absolute $M_k$ magnitudes of the RGB bump and tip are taken from the Yonsei-Yale isochrones. Comparing the observed apparent K magnitude with the derived absolute $M_k$ magnitude, we calculate the distance moduli of the clusters. We discuss the dependency of the derived distance modulus on the cluster age and the uncertainty of the distance measurement from the near-infrared photometry of the RGB bump and tip.

• Journal of Astronomy and Space Sciences
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• v.23 no.2
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• pp.97-104
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• 2006

From the BV images of the metal-poor globular cluster NGC 1904 obtained with the 2K CCD camera equipped on the BOAO 1.8m telescope, we construct (B - V, V) color-magnitude diagram of the cluster. The apparent V magnitudes of the RGB bump and tip have been measured from the luminosity function of the iteratively selected RGB stars in NGC 1904. Theoretical absolute $M_v$ magnitudes of the RGB bump and tip are estimated using the Yonsei-Yale isochrones. The distance modulus of NGC 1904 has been derived by comparing the observed apparent V magnitude with the estimated absolute $M_v$ magnitude of the RGB bump and tip.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.181-183
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• 2006

This paper studies the mechanical behaviors of Sn-3.5Ag solder joint against substrate(such as Au/Ni/Cu, Au/cu, Ni/Cu and Cu pad) after induction heating, a new soldering method. It was found that the solder bump formation depends on the time and current of the induction heating system. Also the heating value of the solder bump were found to vary with respect to the thermal conductivity of the pads on the substrate. In case of Au/Ni/Cu pad and Au/Cu pad, solder bump's shear strength were high for the heating time of $1.5{\sim}2sec$. For Ni/Cu pad, solder bump's shear strength were found to increase with time increment.

• Journal of the Korean Magnetics Society
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• v.4 no.2
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• pp.130-134
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• 1994

This paper describes the occurance of bumps in playback spectrum while reading with MIG heads. The amplitudes of the bumps in theoretically predicted frequencies are investigated by computer simulation. Three cases of MIG head structure are simulated, one without pseudo gaps, the other two with pseudo gap thicknesses of $0.02\;\mu\textrm{m}\;and\;0.2\;\mu\textrm{m}$ on both sides of the main gap, respectively. It is assumed that metal powder tapes are used. The results show that the bumps occur at predicted frequencies and the amplitudes of the bumps agree well with predicted values.

• Laser Solutions
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• v.2 no.1
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• pp.51-60
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• 1999

In this paper, weldability and formability of Tailored-Blank (TB) and the structural impact testing of bump beam were investigated to apply TB to automobile bumper beam. The optimal $CO_2$ laser welding condition for TB of SPFC and SPRC steel plates with different thicknesses was obtained. Before welding, the cross section of butt joint was prepared only by shearing without milling process. Real type bump beam was produced by two kind of forming processes such as roll-forming and press-forming, and the good formability of TB was obtained. Impact test results of bump by using pendulum and barrier were satisfied the impact regulation of bump. Finally. It may be confirmed that laser welded TB is well-balanced material in both weight reduction and production cost of automobile bump.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.803-809
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• 2005

This paper presents the theoretical model to investigate the effect of Coulomb damping in the sub-structure of a foil bearing. Foil deflection is restricted by friction of bumps. Equivalent viscous damping of the bump foils is derived from the Coulomb friction. Dynamic equation of the bumps is constituted by stiffness and damping terms. This point give the difference from Heshmat's frictionless and simple compliance bump model. The fluid is modeled with the compressible Reynolds equation. A perturbation approach is used to determine the static and dynamic performance of the bearing from the coupled fluid-structural model. The analysis result shows that the static and dynamic performance is enhanced by bump friction. This analysis technique would be extended to development of a high performance bearing.