• The Journal of Society for e-Business Studies
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• v.14 no.1
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• pp.143-160
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• 2009

In determining the performance of OLAP database applications, the structure and the effective access methods to the underlying disk system is a significant factor. In recent years, hard disks are designed with multiple physical zones where seek times and data transfer rates vary across the zones. However, there is little consideration of multi-zone disks in previous works. Instead, they assumed a traditional disk model that comes with many simplifying assumptions such as an average seek-time and a single data transfer rate. In this paper, we propose a technique storing a set of materialized views into the multi-zoned disks in OLAP environment dealing with large sets of data. We first present the disk zoning algorithm of materialized views according to the access probabilities of each views. Also, we address the problem of storing views in the dynamic environment where data are updated continuously. Finally, through experiments, we prove the performance improvement of the proposed algorithm against the conventional methods.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.484-487
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• 2005

In order to get the surface characteristics of the HDI of HDD, the surface damage mechanisms must be totally understood. Particle contamination in hard disk drives is a big concern in today's magnetic recording industry since they are major sources of reliability problems. Namely upon contact with the slider or a contaminant particle, the disk may be scratched or the particles may be embedded into the disk surface. In this work, comparison of scratches was made between those found on actual hard disks and those created using a scratch tester. It was found that ramp loading method is an effective way to make similar scratches as the actual ones. From the ramp loading condition, the relationship between the pressure and the scratch track width could be identified.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.179-184
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• 2002

Adhesive contact characteristics of torus-shaped bumps, which are commonly used to reduce friction and stiction in hard disks, are analyzed to examine the applicability to the MEMS structure. The analysis is conducted with the finite element technique considering the adhesive force. Torus-shaped bumps of various rim and bump radii are analyzed. The jump-to-contact behavior, adhesion hysterisis, pull-off forces, contact region and pressure, and surface and subsurface stresses are presented and discussed. Analysis results in the absence of adhesive force are also presented to identify the effect of adhesive force.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.185-188
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• 1991

In this paper we have designed and implemented a method of using extended memory and hard disk space as a data buffer for application programs to allow handling of large data files in DOS environment. We use a part of the conventional DOS memory as a buffer cache which allows the application program to use extended memory and hard disks transparently. Using buffer cache also allows some speed improvement for the application program. We have also implemented a number of functions to allow easier handling of pointer operations used by application programs.

• Tribology and Lubricants
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• v.19 no.2
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• pp.102-108
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• 2003

The height of laser bumps has been considered as the limit of the minimum flying height in the contact start-stop (CSS) of hard disk drives. In this paper, tribological interactions at flying height under laser bumps are investigated in a spin stand for development of ultra-low flying head-disk interface. With the reduction of the spinning speed in a spin stand, the flying height is decreased under the height of laser bumps and, then, head-disk interactions are investigated using AE and stiction/friction signals. During seek tests and 20000 cycle-sweep tests, AE and stiction/friction signals are not significantly changed and there are no catastrophic failures of head-disk interface. Bearing analysis and AFM analysis show that there are signs of wear and plastic deformation on the disks. It is suggested that flying height could be as low as and, sometimes, lower than laser bump height.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1183-1192
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• 2000

This paper relates to the flexural vibration analysis of the hard disk drive (HDD) spindle systems by means of the finite element method. In contrast to previous researches, every system componebt is here analytically modeled taking into account its flexibility and also the centrifugal effect particularly for the disk. To prove the effectiveness and accuracy of the proposed method, commercial HDD spindle systems with two and three identical disks are chosen as examples. Then, their major flexural natural modes are computed employing only a small number of element meshes as the shaft rotaional speed is varied, and compared with the bumerical or experimental results.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.2
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• pp.281-289
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• 1992

In an attempt to simulate the flows in the computer hard disk storage system, flow visualization and quantification by image processing technique were applied. Model geometry was constructed while the dynamic similitude was maintained. Circumferential velocities were mapped out in the transient spin-up phase. During the spin-up phase, fluid close to the rotating inner hub approached the solid body rotation, while the fluid in the outer region showed the velocity deficit compared to the rotating speed of the disks. Effects of presence of read/write head arm assembly between the gap were studied by changing the location of the head. The experimental results could serve as a benchmark for the alidation of numerical codes.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.7
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• pp.784-792
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• 1992

In this paper we design and implement a method for application programs to allow handling of large data files in DOS environment. In this method we use extended memory and hard disk as a data buffer. And we use a part of the conventional DOS memory as a buffer cache which allows the application program to use extended memory and hard disks transparently. Using buffer cache also allows us some speed improvement for the application program.

• Tribology and Lubricants
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• v.16 no.5
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• pp.395-402
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• 2000

The effect of particulate contamination on friction and wear between a negative-pressure picoslider and a laser-textured disk was studied. Particles of different concentrations, materials and sizes were injected to the head-disk interface (HDI), consisting of disks with various textures, at the same speed. In a contaminated environment, durability of head-disk interface gradually decreased as the particle concentration increased. Large particles caused HDI failure early and resulted in an extensive damage to the slider and disk surfaces. Hard particles also caused HDI failure earlier and damages more extensive than soft ones. Based on the test results, mechanisms of HDI failure with picoslider were presented.

• KIISE Transactions on Computing Practices
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• v.23 no.7
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• pp.428-433
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• 2017

Recently, the demand for high performance non-volatile memory storage devices that can replace existing hard disks has been increasing in environments requiring high performance computing such as data-centers and social network services. The performance of such non-volatile memory can greatly depend on the interface between the host and the storage device. With the evolution of storage interfaces, the non-volatile memory express (NVMe) interface has emerged, which can replace serial attached SCSI and serial ATA (SAS/SATA) interfaces based on existing hard disks. The NVMe interface has a higher level of scalability and provides lower latency than traditional interfaces. In this paper, an evaluation and analysis are conducted of the performance of NVMe storage devices through various workloads. We also compare and evaluate the cost efficiency of NVMe SSD and SATA SSD.