• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.618-621
• /
• 2008

The magnetic recording system shows the difference of the magnetic recording density according to the direction of the magnetic field. The yoke shape of the recording system affects the magnetic field direction; therefore, the recording density may be raised by changing the shape. This paper intends not only to increase the magnetic flux density of the record region but also to reduce the recording loss of a specific region through the simultaneous design of the yoke and the magnet. The recording loss can be reduced by minimizing the magnetic flux of the adjacent area to the recording region. The topology optimization method is used to obtain the optimal shape both of the yoke and the magnet. And the commercial package, Maxwell is used to verify the result.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37A no.10
• /
• pp.821-826
• /
• 2012

Two-dimensional magnetic recording (TDMR) is treated as the next generation magnetic recording method, but because of its high channel bit error rate, it is difficult to use in practices. In this paper, we introduce a new writing method that can decrease the nonlinear media error effectively, and it can also achieve 10 Tb/$in^2$ of user bit density on a magnetic recording medium with 20 Teragrains/$in^2$.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.11
• /
• pp.2732-2741
• /
• 2000

Combination of magnetic recording technology and optical recording technology such as Near Field Optical Recording is watched recently. In order to accomplish this technology, the development of an electromagnetic driven mm-sized mirror shifting laser beam in track direction have to needed. In Near Field Optical Recording System, shifting laser beam in track direction mean as fine tracking and means as coarse tracking. Therefore in Near Field Optical Recording, 2-stage actuator is composed of servo controller in reading or recording information on disc layer. In our research, through design and simulation process of driven mm-sized mirror, we arrange systematically design process of driven mm-sized mirror having good frequency transfer characteristics. Design and simulation processes included modal analysis of spring, calculation of magnetic moment according to the number of turns and geometric configuration of coil and magnetic circuit analysis meaning that calculation of magnetic flux density in air gap of magnetic circuit. After that we design and make parts of driven mm-sized mirror, assemble and evaluate our electriomagnetic driven mm-sized mirror. we compared design values with actual characteristic values and present solution scheme. Through these processes we performed manufacturing of an electromagnetic driven mm-sized mirror having good frequency-domain characteristics and high sensitivity characteristics.

• Journal of Magnetics
• /
• v.2 no.4
• /
• pp.147-156
• /
• 1997

An artificially modulated magnetic Co/Pd multilayer is one of the promising candidates for high density magneto-optic (MO) recording media, due to a large Kerr rotation angle in the wavelength of a blue laser beam. However, since multilayer structure, as well as amorphous structure, is a non-equilibrium state in terms of free energy and a MO recording technology is a kind of thermal recording which is conducted around Curie temperature (Tc) of the recording media, when the Co/Pd mulilayer is used for the MO recording media, changes in the magnetic properties are occurred as the amorphous structure do. Therefore, the assessment of the magnetic properties in the Co/Pd multilayer during interdiffusion is crucially important both for basic research and applications. As the parameter of the magnetic properties in this research, saturation magnetization and perpendicular magnetic anisotropy energy of the Co/Pd multilayer are measured in terms of Ar sputtering pressure and heat treatment temperature. Form the results of the research, we find out that the magnetic exchange energy between Co and Pd sublayers strongly affects the changes in the magnetic properties of the Co/Pd multilayers during the interdiffusion in ferromagnetic state. This discovery will provide the understanding of the magnetic exchange energy in the Co/Pd multilayer structure and suggest the operating temperature range for MO recording in the Co/Pd multilayer for the basic research and applications, respectively.

• Journal of the Korean Magnetics Society
• /
• v.1 no.2
• /
• pp.74-78
• /
• 1991

The method for analyzing the recording and reading process of magnetic recording system by numerical simulation is introduced. which can simulate the effect of elements of the magnetic recording system. During the whole simulation, hysteresis characteristics must be included. Preisach model and finite element method are used to construct the algorithm. From the wave of recording current, recorded pattern of magnetization in recording media is simulated in recording process, and then waveform of reading signal in head coil is obtained in reading process. To show the validity of this method, this is applied to perpendicular magnetic recording system. Waveform of recording signal and reproduced signal is obtained in several density. Pattern of reprocuced voltage magnitude according to increase of recording density shows roll-off curve.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2007.05a
• /
• pp.41.1-41.1
• /
• 2007

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.07a
• /
• pp.463-465
• /
• 2002

In order to increase perpendicular magnetic anisotropy of magnetic layer and prepare magnetic recording layer with a good quality by epitaxial growth between magnetic layer and, we prepared Co$\_$77/Cr$\_$20/Ta$_3$/Si doublelayer for perpendicular magnetic recording media which was promoted as next generation recording media on slide glass substrate. The thickness of magnetic layer and Underlayer were varied from 20 to 100 nm and 5 to 100 m, respectively. The surface morphology and crystal structure of the CoCrTa/Si film were examined with XRD and AFM. Prepared thin films showed improvement of dispersion angle of c-axis orientation Δ$\theta$$\_$50/ caused by inserting amorphous Si underlayer.

• Proceedings of the KIEE Conference
• /
• 1990.11a
• /
• pp.28-31
• /
• 1990

In perpendicular magnetic recording system, the magnetic recording and reproduction characteristics of isolated transition of magnetization is simulated in this paper. The recording system which is magneto-static system is analyzed using two-dimensional finite element method and the characteristics of hysteresis of recording media is considered. The results show that the optimizing current is exist in magnetic recording system.

• Journal of the Korean Magnetics Society
• /
• v.16 no.2
• /
• pp.149-156
• /
• 2006

The frequency of the recording current and the rotating speed of the recording media are Increase for the high densities in perpendicular magnetic recording system with high conductive pole tip head and soft magnetic under-layer. In the paper, the frequency Induced eddy current and velocity induced eddy currents are analyzed by non-linear 3-dimensional finite element analysis. It it turned out that the frequency induced eddy current decreases the amplitude of the recording fields, whereas the velocity induced eddy current only distorts the distribution of the recording fields in the recording media.

• Journal of Magnetics
• /
• v.8 no.4
• /
• pp.164-168
• /
• 2003

In high density recording system, the recording head field on a medium should be focused in small bit area and should have a sufficient value to overcome the medium coercivity, which resulted in head saturation. In this paper, an efficient method to access the head field and field gradient considering head saturation is presented. The magnetic vector potential on the head surface is pre-calculated considering head saturation in several cases and accumulated into database. The head field on the recording media is easily produced solving Laplace equation using accessed magnetic vector potential boundaries. The computed head field is compared with a quantified magnetic force microscopy measurement.