• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.676-681
• /
• 2003

In this paper, we investigated the disc warping in high-speed slim-type optical disc drive. Recently, the information storage devices are increasing track density and higher rotation speed to enhance their recording capacity and their data transfer rate. Generally, ODD used in the Lap-top Computer has small inner space. So, the flow instability of inner space is rapidly increased as its higher rotation speed. An extreme case, the flow instability causes the malfunction of readout at pick-up of drives. The experiments and numerical analysis were carried out for several cases, the result shows the influence of airflow to the disc warping.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.1789-1794
• /
• 2004

The present study investigates flow characteristics in an optical disc drive. Detailed knowledge of the flow characteristics is essential to analyze flow-induced noise and vibration, forced convection and flow friction loss. The ODD used in the personal computer is used for the experiment and rotating velocity of disc is under the 4500 rpm. Time-resolved velocity components and velocity spectrum are obtained using the laser Doppler anemometry (LDA). The results show that the front holes reduce now-induced noise and the position of pickup body affects flow near the window. In addition, il is possible for cooling of heat sources in an optical disc drive through measuring the flow fields under the tray.

• Tribology and Lubricants
• /
• v.25 no.6
• /
• pp.421-426
• /
• 2009

The brake system is important part of automobile safety system. The disc brake system is divided two parts: the rotating axisymmetrical disc and the stationary pads. During braking, the kinetic energy and potential energy of moving vehicle were converted into the thermal energy through frictional heat between the brake disc and the pads. The frictional heat, which is generated on the interface of the disc and pads, can cause high temperature during the braking process. The object of present work is to determine temperature and thermal stress, to compare to simulation results and experimental results in the disc by partial 3D model of ventilated disc brake with appropriate boundary conditions. In the simulation process, the mechanical loads were applied to the thermo-mechanical coupling analysis in order to simulate the process of heat produced by friction.

• International Journal of Fluid Machinery and Systems
• /
• v.8 no.3
• /
• pp.183-192
• /
• 2015

The aim of this study was comparative analysis of sediment-induced erosion on optimized design and traditional design of Francis runner blade. The analysis was conducted through laboratory experiments in a test rig called Rotating Disc Apparatus. The results showed that the extent of erosion was significantly less in the optimized design when compared based on the material loss. It was observed that the optimized design could reduce sediment erosion by about 14.4% if it was used in place of the reference design for entire duration of the experiment. Based on the observations and results obtained, it has been concluded that the optimization of hydraulic design of blade profile of Francis runner can significantly reduce the effect of sediment-induced erosion.

• Resources Recycling
• /
• v.10 no.1
• /
• pp.42-48
• /
• 2001

The dissolution behavior of gold and silver from gold-silver alloys in aerated cyanide solutions has been investigated by an electrochemical means as well as a direct measurement of gold and silver ions reported in the bulk solution as a function of time using rotating disc electrodes. The variables studied included oxygen partial pressure, rotating speed of the disc, concentration of cyanide, temperature and composition of the allyos. The dissolution potential and the rate of dissolution were obtained in view of the anodic and cathodic current-potential relationships. The results were discussed in terms of the mixed potential theory. The results showed that the dissolution rate of gold and silver from the alloys was controlled partially by chemical reaction. but largely by transport of either oxygen or cyanide, depending on their relative concentration under the experimental conditions employed in this study.

• Advances in aircraft and spacecraft science
• /
• v.5 no.3
• /
• pp.295-318
• /
• 2018

This research studies thermo-elastic behavior of rotating micro discs that are employed in various micro devices such as micro gas turbines. It is assumed that material is functionally graded with a variable profile thickness, density, shear modulus and thermal expansion in terms of radius of micro disc and as a power law function. Boundary condition is considered fixed-free with uniform thermal loading and elastic field is symmetric. Using incompressible material's constitutive equation, we extract governing differential equation of four orders; to solution this equation, we utilize general differential quadrature (GDQ) method and the results are schematically pictured. The obtained result in a particular case is compared with another work and coincidence of results is shown. We will find out that surface effect tends to split micro disc's area to compressive and tensile while nonlocal parameter tries to converge different behaviors with each other; this convergence feature make FGIMs capable to resist in high temperature and so in terms of thermo-elastic behavior we can suggest, using FGIMs in micro devices such as micro turbines (under glass transition temperature).

• Proceedings of the Membrane Society of Korea Conference
• /
• 2001.11a
• /
• pp.131-134
• /
• 2001

• Proceedings of the Membrane Society of Korea Conference
• /
• 2000.11a
• /
• pp.146-149
• /
• 2000

• Tribology and Lubricants
• /
• v.26 no.1
• /
• pp.31-36
• /
• 2010

The brake system is an important part of the automobile safety system. The disc brake system is divided into two parts: a rotating axi-symmetrical disc, and the stationary pads. The frictional heat, which is generated on the interface of the disc and pads, can cause high temperatures during the braking process. The frictional heat source (the pads) is moving on the disc and the location is time-dependent. Our study applies a moving heat source, which is defined by the time and space variable on the frictional surface, in order to simulate the frictional heat behavior accurately during the braking process. The object of the present work is the determination of the temperature distribution and thermal stress in the solid disc by non-axisymmetric 3D modeling for repeated braking.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.4 no.3
• /
• pp.1-9
• /
• 1984

A mult-stage rotating biological contactor process was evaluated by using the mixtures of nightsoil and sewage as influent substrate. An emphasis was concentrated on the BOD removal efficiency at each stage of the process with respect to hydraulic detention times, rotating speeds of the disc and influent organic substrate concentrations. The results indicated that the process was found to be economically feasible when operated at hyduraulic detention time of 2 hours and disc rotating speed of 3 RPH. As to treatment efficiency, BOD removal efficiency of 40 to 50 percent could be obtained at the first stage regardless of influent organic substrate concentrations. The overall BOD removal efficiency of the process was found to be 88 to 90 percent at even high organic loading of $2.0kgBOD/m^3{\cdot}day$.