• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.413-418
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• 2004

Recently, the development of mobile devices demands information storage systems to use micro drive devices. 1-inch micro drive hard disk uses the load/unload(L/UL) technology to increase area recording density and reduce power consumption. Because micro drive has light actuator, effects of the flexible cable that is ignored in 3.5-inch hard disk drive is important to load/unload performances. In this paper, effects of flexible cable on load/unload performances are studied.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.484-489
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• 2001

Recent trends in information storage devices disk are the transition from CD drives to high density DVD drives, the development of writable disk drives and the appearance of several high-density portable disk drives. In some flexible disk drives, self-excited disk vibrations become severe as rotation speed increases near or above critical speed. Critical speeds of CD/DVD, ASMO and floppy disks are experimentally measured and compared with analytical predictions. Flutter instability caused by aero-induced disk vibration at high speeds are experimentally observed. In ASMO, three nodal-diameter mode experiences its flutter at 8750 rpm with the frequency lock-on phenomenon. The CD/DVD disk does not have the aero-induce flutter up to 14,000 rpm.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.5
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• pp.952-959
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• 2002

The natural frequencies of a flexible spinning disk misaligned with the axis of rotation are studied in an analytic manner. The effects of misalignment on the natural frequency need to be investigated, because the misalignment between the axis of symmetry and the axis of relation cannot be avoided in the removable disks such as CD-R, CD-RW or DVD disks. Assuming that the in -plane displacements are in steady state and the out-of-plane displacement is in dynamic state, the equations of motion are derived for the misaligned spinning disk. After the exact solutions are obtained fur the steady -state in-plane displacements, they are plugged into the equation for the dynamic-state out-of-plane motion. The resultant equation is a linear equation for the out -of-plane displacement, which is discretized by the Galerkin method. Based on the discretized dquations, the effects of the misalignment are analyzed on the vibration characteristics of the spinning disk, i.e., the natural frequencies and the critical speed.

• Steel and Composite Structures
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• v.18 no.3
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• pp.775-791
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• 2015

An analytical and experimental investigation is performed into the mechanical behavior of carbon-fiber/epoxy woven coned annular disk springs. An analytical approach is presented for predicting the deformation behavior of disk springs of specially orthotropic laminates with arbitrary geometric parameters. In addition, an analytical methodology is proposed for obtaining the deformation behavior of a stack of disk springs. The methodology is capable of accounting for parallel and series arrangements for uniform and irregular stacks. Element and assembly experimental results are used to validate the proposed method showing how to achieve flexible spring rates at various deflections ranges. This manuscript also provides guidelines for design and validation of disk spring assemblies.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.848-851
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• 2007

Recently, as the demand of the information storage devices with large storage capacity such as BD(Blu-ray Disk) and HDTV(high-definition television) is increased, the optical storage devices are also required to have fast data transfer rate and large storage capacity. To satisfy these requirements, the actuator for optical disk drive should have high flexible mode frequencies for system stability. In this paper, we suggested a moving magnet type actuator having high flexible mode frequency. However, the moving magnet type actuator does not have sufficient driving sensitivities due to the weight of its moving part. To improve driving sensitivities, we designed the model with the closed electromagnetic circuit for tracking direction. In addition, driving sensitivities and flexible mode frequencies were improved by using DOE(Design of Experiments) for magnetic circuit and modifying the lens holder. Consequently, it is confirmed that the designed model is satisfied with the desired specifications.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.5
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• pp.13-24
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• 2000

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.12 no.3
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• pp.116-129
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• 2000

The interaction of incident monochromatic waves with a tensioned, flexible, circular membrane submerged horizontally below free surface is investigated in the frame of three-dimensional linear hydro-elastic theory. The velocity potential is split into two parts i.e. the diffraction potential representing the scattering of incident waves by a rigid circular disk and the radiation potential describing motion induced waves by elastic responses of flexible membrane. The fluid domain is divided into three regions, and the diffraction and radiation potentials in each region are expressed by the Fourier Bessel series. The displacement of circular membrane is expanded with a set of natural functions, which satisfy the membrane equation of motion and boundary conditions. The unknown coefficients in each region are determined by applying the continuity of pressure and normal velocity at the matching boundaries. The results show that various types of wave focusing are possible by controlling the size, submergence depth, and tension of membrane.

• Journal of KSNVE
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• v.9 no.4
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• pp.806-812
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• 1999

Dynamic behaviors are analyzed for a flexble spinning disk with angular acceleration, considering geometric nonlinearity. Based upon the Kirchhoff plate theory and the von Karman strain theory, the nonlinear governing equations are derived which are coupled equations with the in-plane and out-of-planedisplacements. The governing equations are discretized by using the Galerkin approximation. With the discretized nonlinear equations, the time responses are computed by using the generalized-$\alpha$ method and the Newton-Raphson method. The analysis shows that the existence of angular acceleration increases the displacements of the spinning disk and makes the disk unstable.

• Journal of the Korean Society for Railway
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• v.14 no.2
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• pp.100-108
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• 2011

This paper investigates the structural stability and reliability on improving performance of flexible brake pad used in high speed train. To this end, an improved model of flexible pad was obtained through structural analysis. Brake pad specimens were subjected to modal, stroke and endurance tests to examine the dynamic characteristics and mechanical stability. The hot spot generation with increasing rotational speed was observed on chassis dynamometer equipment and then the structurally uniform contact between the disc and pad was achieved. The temperature distribution of flexible pad was measured using the infrared camcorder. Hence, the proposed flexible pad showed the better structural stability and thermal energy emission.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.597-603
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• 2010

Metallic sintered brake pads are often applied to Mid/High Speed Train due to its high strength and thermal characteristics. Because of its imbalance contact between discs and pads can greatly influence the life span, one sided wear, discs attack/crack and threat the safety of the train during operation. In this research, we analyzed pressure/temperature distribution between brake pads and disks. Analyzed data had been verified and modified to conduct further tests of Flexible brake pads with small/full-scale dynamo test. Flexible brake pads were installed to TTX train to conduct further tests to identify the differences between Rigid brake pads and Flexible brake pads. In result, Flexible brake pads showed outstanding disk thermal stability, one sided wear, noise and life of pad than rigid brake pad.