Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korean Society of Tribologists and Lubrication Engineers
Journal Basic Information
Journal DOI :
The Korean Society of Tribologists and Lubrication Engineers
Editor in Chief :
Volume & Issues
Volume 22, Issue 6 - Dec 2006
Volume 22, Issue 5 - Oct 2006
Volume 22, Issue 4 - Aug 2006
Volume 22, Issue 3 - Jun 2006
Volume 22, Issue 2 - Apr 2006
Volume 22, Issue 1 - Feb 2006
Selecting the target year
Effect of Relative Humidity, Disk Acceleration, and Rest Time on Tribocharge Build-up at a Slider-Disk Interface of HDD
Hwang J. ; Lee D.Y. ; Lee J. ; Choa S.H. ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 22, issue 2, 2006, Pages 59~65
In hard disk drives as the head to disk spacing continues to decrease to facilitate recording densities, slider disk interactions have become much more severe due to direct contact of head and disk surfaces in both start/stop and flying cases. The slider disk interaction in CSS (contact-start-stop) mode is an important source of particle generation and tribocharge build-up. The tribocharge build-up in the slider disk interface can cause ESD (electrostatic discharge) damage. In turn, ESD can cause severe melting damage to MR or GMR heads. The spindle speed of typical hard disk drives has increased in recent years from 5400 rpm to 15000 rpm and even higher speeds are anticipated in the near future. And the increasing disk velocity leads to increasing disk acceleration and this might affect the tribocharging phenomena of the slider/disk interface. We investigated the tribocurrent/voltage build-up generated in HDD, operating at increasing disk accelerations. In addition, we examined the effects with relative humidity conditions and rest time. We found that the tribocurrent/voltage was generated during pico-slider/disk interaction and its level was about
, respectively. Tribocurrent/voltage build-up was reduced with increasing disk acceleration. Higher humidity conditions
produced lower levels tribovoltage/current. Therefore, a higher tribocharge is expected at a lower disk acceleration and lower relative humidity condition. Rest time affected the charge build-up at the slider-disk interface. The degree of tribocharge build-up increased with increasing rest time.
Prediction of Combination-Type-Staggered-Labyrinth Seal Leakage Using CFD
Ha Tae-Woong ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 22, issue 2, 2006, Pages 66~72
Leakage reduction through annular type labyrinth seals of steam turbine is necessary for enhancing their efficiency and the precise prediction method of seal leakage is needed. In this study, numerical analysis for leakage prediction of the combination-type-staggered-labyrinth seal has been carried out using FLUENT 6 which is commercial CFD (Computational Fluid Dynamics) code based on FVM (Finite Volume Method) and SIMPLE algorism. The present CFD results are verified with the theoretical analysis based on Bulk-flow concept which has been mainly used in predicting seal leakage. Comparing with the result of Bulk-flow model analysis, the leakage result of CFD analysis shows good agreement within 7.1% error.
A Study on Wear Characteristics of Machine Structural Steel by Surface Modification
Park Heung-Sik ; Woo Kyu-Sung ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 22, issue 2, 2006, Pages 73~78
The surface modification of automobile parts is of great technological importance for the improvement of corrosion resistance, wear resistance, fatigue strength and so on. Recently, research on the development of the technology of surface modification substituting 6-balance chrome process has progressively been achieved in automobile parts. Although the innovation technology for the improvement of the corrosion-resisting and wear resistant properties through post oxidation after nitrocarburising process had attracted a great attention. For this, anodically potentiodynamic polarisation testing was carried out to corrosion resistance and friction and wear experiment according to applied load and sliding distance was carried out to evaluate the wear resistance of machine structural steel with nitrocarburising and non-nitrocarburising SM45C. The presumed wear volume was calculated with the image processing far evaluation of wear resistance of two materials. The results show that the nitrocarburising had a distinguished corrosion resistance and wear resistance than non-nitrocarburising.
Profile Design of the Inner Rotor of a Gerotor by the Composite Curve of Circular Arcs
Lee Sung-Chul ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 22, issue 2, 2006, Pages 79~86
As the gerotor set with ideal profile meshes too tight, the reduction in the size of the rotor is generally adopted for a smooth operation. In this paper, a method of the profile modification for providing clearances was proposed. The meshing properties of the gerotor were analyzed and the non-boundary section of the inner rotor was identified, which denoted that the adjacent chambers were in the same pressure state. Clearances were imposed on the non-boundary section of the inner rotor, and then the profile of that section was modified as a composite curve of arcs. The other sections of the inner rotor were also interpolated as arcs. Thus, the whole profile of the inner rotor was designed as a composite curve of arcs.
Evaluation Technology for Brake Performance of Tread Brake Shoe
Choi Kyung-Jin ; Lee Hi-Sung ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 22, issue 2, 2006, Pages 87~92
In tread brake of freight cars, brake force is produced by the friction between the wheel and the brake shoe. Friction coefficients associated with the brake power, weight variation and brake shoe types should be sensitively treated as the design parameters. The conditions of the car, empty and loaded, should also be taken into consideration in brake force design and the control of brake force has some limitations in terms of the brake system design so that the brake friction materials selection should be considered as important measures to solve that difficulties. Friction characteristics of brake friction materials should remain within the range of maximum and minimum value and the friction performance should remain stable regardless of brake time and temperature. This study presented an experimental evaluation method to secure optimum brake performance by keeping safe brake effect and brake distance by the friction coefficient of the brake shoe of the freight cars.
Finite Difference Analysis of Dynamic Characteristics of Negative Pressure Rectangular Porous Gas Bearings
Hwang Pyung ; Khan Polina ; Lee Chun-Moo ; Kim Eun-Hyo ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 22, issue 2, 2006, Pages 93~98
The numerical analysis of the negative pressure porous gas bearings is presented. The pressure distribution is calculated using the finite difference method. The Reynolds equation and Darcy's equation are solved simultaneously. The air bearing stiffness and damping are evaluated using the perturbation method. Rectangular uniform grid is employed to model the bearing. The vacuum preloading is considered. The pressure in the vacuum pocket is assumed to be a constant negative pressure. The total load, stiffness, damping and flow rate are calculated fur several geometrical configurations and several values of negative pressure. It is found that too large vacuum pocket can result in negative total force.
A Study on the Changes in Dielectric Constant of Engine Oil
Chun Sang-Myung ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 22, issue 2, 2006, Pages 99~104
The dielectric constants of fresh engine oils were obtained according to various types of oil, temperatures and frequencies. Through analyzing the characteristics of dielectric constant, the related correlation between the changes in dielectric constant of oil and the degree of oil deterioration is going to be found. The dielectric constant was calculated by cross capacitances measured by a sensor tube. Before finding the correlation, as a prerequisites study, the best condition measuring the dielectric constant was found. In general, it was found that the value of dielectric constant became stable below
regardless frequency variation. Further, above 6kHz, the dielectric constant became stable even if temperature had been above
Study on the Experiment of the Floating Ring Seal with Bump Foil for High Pressure Turbopump
Kim Kyoung-Wook ; Kim Chang-Ho ; Ahn Kyoung-Min ; Lee Sung-Chul ; Lee Yong-Bok ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 22, issue 2, 2006, Pages 105~111
The floating ring seal which is used in the high pressure turbo pump is frequently used in the oxidizer pump and the fuel pump of the turbo pump of the liquid propulsion rocket, because it is able to minimize clearance to decrease the leakage flow rate. Compared with contact seal, the floating ring seal has advantage of minimizing clearance without rubbing phenomenon. But, the floating ring seal has a tendency to increase instability in operating condition in the high speed region. In this research, we devised floating ring seal which is inserted bump in the outer surface in order to improve the stability in the high speed region. Through this work, we expect to improve stability of floating ring seal with increasing the direct damping coefficient of seal and decreasing the eccentricity ratio.