• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.7
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• pp.1179-1184
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• 2003

The technique for measuring the rotational speed of tappet in direct acting type valve train system has been developed. The optic signal monitoring system with laser and optic fiber was designed to follow the signal of tappet rotation. The system was based on ON/OFF signal generation from the additional encoder teeth under the tappet with optic fibers attached photo transistor. The data showed that tappet rotation was affected by offset, oil temperature and cam shaft operating speed. Also it was found that tappet rotation increases with oil temperature. Tappet spin was delayed 10∼s20$^{\circ}$ cam angle after valve opening. The instantaneous rotational speed of tappet was reciprocal to cam shaft speed and the tappet and the cam angle ratio was located in the range of 0.1∼0.3.

• Honam Mathematical Journal
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• v.39 no.3
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• pp.363-377
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• 2017

In the present study we consider the generalized rotational surfaces in Euclidean spaces. Firstly, we consider generalized spherical curves in Euclidean (n + 1)-space ${\mathbb{E}}^{n+1}$. Further, we introduce some kind of generalized spherical surfaces in Euclidean spaces ${\mathbb{E}}^3$ and ${\mathbb{E}}^4$ respectively. We have shown that the generalized spherical surfaces of first kind in ${\mathbb{E}}^4$ are known as rotational surfaces, and the second kind generalized spherical surfaces are known as meridian surfaces in ${\mathbb{E}}^4$. We have also calculated the Gaussian, normal and mean curvatures of these kind of surfaces. Finally, we give some examples.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.7
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• pp.611-617
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• 2004

This paper presents a simple method of rotational motion estimation and correction for roll axis stabilization of an image. The scheme first computes the rotation center by taking least squares of selected local velocity vectors, and the rotational angle is found from special subset of motion vectors. Roll motion correction is then performed by the nearest neighbor interpolation technique. To show the effectiveness of our approach, the synthetic and real images are evaluated, resulting in better performance than the previous ones.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.6
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• pp.353-360
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• 2018

This paper is to investigate the micro-behavior of the double-span beams with WUF-W seismic connection under combined axial tension and moment and to propose the rational rotational capacity of it for progressive collapse-resistant analysis and design addressing the stress and strain transfer mechanism. To this end, the behavior of the double-span beams under the column missing event is first investigated using the advanced nonlinear finite element analysis. The characteristics of fracture indices of double-span beams with WUF-W connection under combined axial tension and flexural moment are addressed and then proposed the rational rotational capacity as the basic datum for the progressive collapse-resistant design and analysis. The distribution of fracture indices related to stress and strain for the double-span beams is investigated based on a material and geometric nonlinear finite element analysis. Furthermore, the micro-behavior for earthquake and progressive collapse is explicitly different.

• Journal of the Korea Concrete Institute
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• v.11 no.6
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• pp.47-56
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• 1999

In this paper, a nonlinear finite element procedure is presented for the analysis of reinforced concrete shell structures. The 4-node quadrilateral flat shell finite element with drilling rotational stiffness is developed. The layered approach is used to discretize behavior of concrete and reinforcement through the thickness. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. The steel reinforcement is assumed to be in a uniaxial stress state and to be a smeared in a layer. The proposed numerical method for nonlinear analysis of reinforce concrete shells will be verified by comparison with reliable experimental results.

• Bulletin of the Korean Chemical Society
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• v.28 no.10
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• pp.1697-1704
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• 2007

We present results for transport properties of diatomic fluids by isothermal-isobaric (NpT) equilibrium molecular dynamics (EMD) simulations using Green-Kubo and Einstein formulas. As the molecular elongation of diatomic molecules increases from the spherical monatomic molecule, the diffusion coefficient increases, indicating that longish shape molecules diffuse more than spherical molecules, and the rotational diffusion coefficients are almost the same in the statistical error since random rotation decreases. The calculated translational viscosity decreases with the molecular elongation of diatomic molecule within statistical error bar, while the rotational viscosity increases. The total thermal conductivity decreases as the molecular elongation increases. This result of thermal conductivity for diatomic molecules by EMD simulations is again inconsistent with the earlier results of those by non-equilibrium molecular dynamics (NEMD) simulations even though the missing terms related to rotational degree of freedom into the Green-Kubo and Einstein formulas with regard to the calculation of thermal conductivity for molecular fluids are included.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.9
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• pp.89-96
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• 1999

This paper presents the optimization design technique on the joint stiffness and section characteristic factors of chassis frame, by using beam and spring elements in a given design package. Two correction methods are used for the optimization design of chassis frame. First is the equivalent inertia of moment method in relation to the section characteristic factors of joint zones, which are thickness , width and height of frame channel section. Second is the rotational spring element with joint stiffness of joint zones. The CAE example shows that the relationship of section characteristic factors and joint stiffness can effectively be used in designing chassis frame. In this point, if static and dynamic targets are given, the joint-zone and section characteristic factors of chassis frame intended may be designed and defined by using beam and rotational spring elements.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.8
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• pp.1069-1076
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• 2002

Contamination particles in a hard disk drive can cause serious problems including slider crash and thermal asperities. A recirculation filter is typically installed in the hard disk drive to remove the particles. Measurements and theoretical predictions of particle concentration decay with the filter are carried out for a commercially available HDD. Especially, the effect of disk rotational speed on the particle capture efficiency is investigated. Results show that filter efficiency is higher for higher disk rotational speed.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.551-556
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• 2004

The theoretical method is developed to investigate the vibration characteristics of the combined cylindrical shells with an annular plate joined to the shell at any arbitrary axial position. The structural rotational coupling between shell and plate is simulated using the rotational artificial spring. For the translational coupling, the continuity conditions for the displacements of shell and plate are used. For the uncoupled annular plate, the transverse motion is considered and the in-plane motions are not. And the additional transverse and in-plane motions of the coupled annular plate by shell deformation are considered in analysis. Theoretical formulations are based on Love's thin shell theory. The frequency equation of the combined shell with an annular plate is derived using the Rayleigh-Ritz approach. The effect of inner-to-outer radius ratio, axial position and thickness of annular plate on vibration characteristics of combined cylindrical shells is studied. To demonstrate the validity of present theoretical method, the finite element analysis is performed.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.219-224
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• 2004

In recent years, as the demands of VBNS(Very high speed Backbone Network Service) and VDSL(Very high-data rate Digital Subscriber Line) increase, the development of kernel parts of optical communication such as PLC(Planar Light Circuit), Coupler, WDM elements increase. The alignment and the attachment technology are very important to fabricate the optical elements for communication. In this paper, the mechanism of rotational stage, the contact sensing unit, and integrated control circuit for the optical alignment system are studied.