• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.341.2-341
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• 2002

As the data storage device market demands higher data transfer rate with higher track density, TMR budget is to be tighter so that even minor improvement is sought in HDD development fields. Disk flutter associated with the turbulent air flow inside the chamber becomes of great interest for the reduction of PES especially at OD. A comparative transient turbulent flow study is presented in this paper for the reduction of disk flutter with different housing designs.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.319.2-319
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• 2002

The main obstacle to high track density in HDD id the structural resonances of the suspension. The most critical mode is sway mode and second torsion mode, when a data is read and written. It is common fact that the effect of two modes is smaller when a thickness is bulky. But the stiffness of suspension is smaller, the slider can follow a disk better. Because these two fact are reciprocal, a compromise is needed. So we investigated another method to improve band width without changing of the thickness of suspension but with changing of the shape. (omitted)

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.338.2-338
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• 2002

Passengers in automobile or train are exposed to a worse noise environment when they are in the tunnel than in the open field. This is due to a relatively higher space density of sound energy by multiple reflection phenomenon of noise generated by operation of transportaton vehicles from tunnel wall compared to open field. In this study, noise characteristics of subway train running through a tunnel were investigated at straight/cruved track and tunnel type(semi circula/box). (omitted)

• 대한전자공학회논문지
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• 제24권6호
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• pp.1049-1055
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• 1987

This paper describes a near-optimal standard cell layout strategy which consists of three consecutives steps` partition, placement, and routing. In the partition step, a given network is torn apart into many subnetworks such that each subnetworks contains as many cells as possible with minimum interocnnections between subnetwork. In the placement step, the conventional string placement algorithm was modified. Also, bonding pads were placed such that their connections to the related cells are shortest. As a result for the tested example, the placement time was saved by 60% and the total routing lengths were saved by more than 20% and substantial improvements in the number of feed-through cell and the track density were obtained. The layout program is coded in PASCAL and implemented on a VAX 11-750/UNIX computer.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.58-64
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• 2001

An investigation of the TMR(Track Misregistration) requirements to achieve the capacity of 80GBytes／Platter in 7200rpm disk drive system is reported. This paper also gives an overview of the PES(Position Error Signal) characteristics in the 57,500TPI disk drive to estimate the required 95,000TPI-system PES. The TMR measured by PES are presented and decomposed in order to identify the portions and their contributions of the spindle-disk system vibration and HSA(Head-Stack-Assembly) system vibration respectively. A comprehensive review on the servo system is also presented to provide the practical limits of the modem servo architecture into TMR budget design. The decomposed PES energy distribution shows that the spindle-disk pack vibration is one of the top-ranking sources of the total TMR budget and its percentage contribution is about 50％ considering all the other TMR sources.

• 한국세라믹학회지
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• 제45권12호
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• pp.788-795
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• 2008

An electrolyte supported SOFC cell was tested at $800^{\circ}C$ in air for 3600 h with an applied current density of $200\;mA/cm^2$ to examine possible cathode degradation issues. A scandium- stabilized zirconia (ScSZ) with additional manganese doping (ScSZ: Mn) was used as electrolyte. A strontium and copper-doped lanthanum ferrite (LaSrCuFe) and platinum were used as cathode and quasi-anode material, respectively. The DC resistance was logged over the complete testing period. Additionally, impedance spectroscopy was used from time to time to track changes of the cell in-situ. Post-test analysis of the cell using methods like scanning electron microscopy imaging and other electrochemical testing methods allow the identification of different degradation sources. The results indicate a promising combination of electrolyte and cathode material in terms of chemical compatibility and electrical performance.

• 한국수산과학회지
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• 제28권6호
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• pp.720-727
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• 1995

A Monte Carlo computer simulation study was conducted to determine the most efficient sampling design for the blue crab dredge capture efficiency experiment performed in Chesapeake Bay, Maryland, U. S. A. The input values were the number of dredge tracks in each experimental area, the number of tows per experiment, the number of experiments, the mean density of crabs per unit area, the negative binomial coefficient, the gear capture efficiency, and the tow error. As a result of the study, a four-track experiment with twenty to twenty-eight tows was estimated to be the best in terms of precision and accuracy of the gear capture efficiency.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.676-681
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• 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.

• Tribology and Lubricants
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• 제11권5호
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• pp.108-113
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• 1995

Wear and friction behavior of plasma-sprayed coatings in Mo- and Co-based alloy were studied for the application of piston-ring automobile engine. The plasma-sprayed coatings were varied with gun current density, gas flow, and distance. The surface roughness, microhardness, and wear volume were measured depending on the spray distances. The high temperature hardness value were also measured as a function of temperature. Ball-on-disc geometry configuration tribometer was utilized in air. The wear tests were performed in the temperature ranges from room temperature to 825$^{\circ}$C to investigate the tribological trend of the piston-ring materials in the lack of lubricant. The cross sections of wear track were investigated, using microscopy.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.419-424
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• 1996

As track density increases, the effects of nonlinearity in pivot bearing of hard disk drive on the servo performance are becoming more important in considering the range of inertia force and the input torque during settling and tracking mode. Recently, an increasing attention is given to more precise experimental observations and modelings of pivot nonlinearity for achieving higher performance of servo control. In this paper, we propose a new model that shows an improved prediction of the pivot nonlinearity than existing preload-plus-two-slope model at matching simulations and experimental results in both time and frequency domains. Experimental measurements are carried out to validate and identify the specific nonlinearity presents in the pivot bearing when its in fine motion. Using the experimental results new model along with the existing one are characterized and compared for relevancies.