• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.660-665
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• 2006

This paper presents a finite element method to analyze the free and forced vibration of a hard disk drive (HDD) considering the flexibility of a spinning disk-spindle with fluid dynamic bearings (FDBs), an actuator with pivot bearings, an air bearing between head-disk interface and the base with complicated geometry. Finite element equation of each component is consistently derived with the satisfaction of the geometric compatibility of the internal boundary between each component. The spinning disk, hub and FDBs are modeled by annular sector elements, beam elements and stiffness and damping elements, respectively. The actuator am, E-block, suspension and base plate are modeled by tetrahedral elements. The pivot bearing in the actuator and the air bearing between head-disk interfaces are modeled by the stiffness element with five degrees of freedom and the axial stiffness, respectively. A global matrix equation obtained by assembling the finite element equations of each substructure is transformed to a state-space matrix-vector equation, and both damped natural frequencies and modal damping ratios are calculated by solving the associated eigenvalue problem with the restarted Arnoldi iteration method. Modal and shock testing are performed to show that the proposed method well predicts the vibration characteristics of a HDD.

• 한국소음진동공학회논문집
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• 제15권6호
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• pp.749-756
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• 2005

This paper presents vibration analyses of hard disk drive (HDD) spindle systems based on the finite element method. The systems under investigation have a cantilevered shaft rotating on hydrodynamic bearings. In particular, the influence of stator's flexibility on major modes has been taken into account in dual ways lumped and distributed-parameter model approfches. Even the latter employs relatively macroscopic elements instead of extremely fine ones Popular in commercial codes. In order to prove the effectiveness of such formulated models, two types of HDD prototypes featuring different hub and stator structures are selected as examples. Compared to the first, the second type has a reinforced stator that would raise the natural frequency of the hub's translational (or sideway) mode. Both free and forced vibration characteristics are computed, and subsequently compared with the experimental data. It is our conclusion that Particularly the Proposed distributed model method is an efficient design tool for state-of-the-art HDD spindle systems.

• Journal of Information Science Theory and Practice
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• 제10권spc호
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• pp.56-65
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• 2022

Korea Institute of Science and Technology Information (KISTI) is a Worldwide LHC Computing Grid (WLCG) Tier-1 center mandated to preserve raw data produced from A Large Ion Collider Experiment (ALICE) experiment using the world's largest particle accelerator, the Large Hadron Collider (LHC) at European Organization for Nuclear Research (CERN). Physical medium used widely for long-term data preservation is tape, thanks to its reliability and least price per capacity compared to other media such as optical disk, hard disk, and solid-state disk. However, decreasing numbers of manufacturers for both tape drives and cartridges, and patent disputes among them escalated risk of market. As alternative to tape-based data preservation strategy, we proposed disk-only erasure-coded archival storage system, Custodial Disk Storage (CDS), powered by Exascale Open Storage (EOS), an open-source storage management software developed by CERN. CDS system consists of 18 high density Just-Bunch-Of-Disks (JBOD) enclosures attached to 9 servers through 12 Gbps Serial Attached SCSI (SAS) Host Bus Adapter (HBA) interfaces via multiple paths for redundancy and multiplexing. For data protection, we introduced Reed-Solomon (RS) (16, 4) Erasure Coding (EC) layout, where the number of data and parity blocks are 12 and 4 respectively, which gives the annual data loss probability equivalent to 5×10^-14. In this paper, we discuss CDS system design based on JBOD products, performance limitations, and data protection strategy accommodating EOS EC implementation. We present CDS operations for ALICE experiment and long-term power consumption measurement.

• 대한기계학회논문집
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• 제16권2호
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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.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2000년도 추계학술대회 논문집
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• pp.265-267
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• 2000

The objective of this study is to analyze, design and evaluate a new gas cleanup or sampling system that will remove erosive, corrosive, and fouling contaminants present in an effluent stream as either solid or liquid particles providing a clean gas stream. The gas clean-up or sampling system considered in this study is an irrigated, rotating element device. The device consists of a central disk-like hub from which emanate radially wires or cylindrical elements. (omitted)

• 한국융합학회논문지
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• 제11권6호
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• pp.209-213
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• 2020

본 연구에서는 경주용 자동차에서 기존에 사용 중인 형상을 가진 모델 A와 경량화를 한 모델 B를 설계하고 열 변형과 열응력을 동반한 구조해석을 하였다. Model A가 Model B에 비하여 최고온도가 낮음을 보인다. 다른 냉각 조건이 주어지지 않고 디스크의 형상에 따른 냉각성능은 Model A가 더 뛰어남을 알 수 있다. Model A가 Model B에 비하여 거의 2배 이상으로 그 열응력이 낮아져 내구성면에서도 우수함을 알 수 있었다. 응력이 가장 크게 나타나는 부분은 형상에 관계없이 허브와 접합되는 구멍으로 나타났다. 본 연구에서의 해석결과는 실제 자동차 브레이크 디스크의 형상을 설계하는데 있어서 유용하다고 보인다. 본 연구에서 얻은 해석 결과는 실제적으로 경주용 자동차 브레이크 디스크의 강도를 파악하는 데에 적용될 수 있다. 경주용 자동차 브레이크 디스크의 해석 결과를 이용함으로서, 본 연구가 미적인 설계 및 해석이 적용된 융합 연구라고 보여진다.

• 한국소음진동공학회논문집
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• 제19권6호
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• pp.614-619
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• 2009

The STW(servo track writing) system which is the process of writing servo signals on disks before assembling in drives uses the spindle motor-chuck mechanism to realize low cost because the spindle motor-chuck mechanism has merit which can simultaneously write multi-disk by piling up disks in hub. Therefore, when the spindle motor-chuck mechanism of horizontal type operates in high rotation speed it is necessary to reduce the effect of RRO(repeatable run-out) and NRRO(non-repeatable run-out) to achieve the high precision accuracy of nano-meter level during the STW process. In this paper, we analyzed that the slip in assembly surfaces can be caused by the mechanical tolerance and clamping force in hub-chuck mechanism and can affect NRRO performance. We designed springs for centering and clamping considering centrifugal force by the rotation speed and assembly condition. The experimental result showed NRRO performance improves about 30 % than case of weak clamping force. The result shows that the optimal design of the spindle motor-chuck mechanism can effectively reduce the effect of NRRO and RRO in STW process.

• 한국소음진동공학회논문집
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• 제15권3호
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• pp.251-258
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• 2005

The free vibration of a spinning flexible disk-spindle system supported by hydro dynamic bearings (HDB) in an HDD is analyzed by FEM. The spinning flexible disk is described using Kirchhoff plate theory and von Karman non-linear strain, and its rigid body motion is also considered. It is discretized by annular sector element. The rotating spindle which includes the clamp, hub, permanent magnet and yoke, is modeled by Timoshenko beam including the gyroscopic effect. The flexible supporting structure with a complex shape which includes stator core, housing, base plate, sleeve and thrust pad is modeled by using a 4-node tetrahedron element with rotational degrees of freedom to satisfy the geometric compatibility. The dynamic coefficients of HDB are calculated from the HDB analysis program, which solves the perturbed Reynolds equation using FEM. Introducing the virtual nodes and the rigid link constraints defined in the center of HDB, beam elements of the shaft are connected to the solid elements of the sleeve and thrust pad through the spring and damper element. The global matrix equation obtained by assembling the finite element equations of each substructure is transformed to the state-space matrix-vector equation, and the associated eigen value problem is solved by using the restarted Arnoldi iteration method. The validity of this research is verified by comparing the numerical results of the natural frequencies with the experimental ones. Also the effect of supporting structures to the natural modes of the total HDD system is rigorously analyzed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.572-578
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• 2003

The free vibration of a spinning flexible disk-spindle system supported by hydro dynamic bearings in a HDD is analyzed by FEM. The spinning flexible disk is described using Kirchhoff plate theory and von Karman non-linear strain, and its rigid body motion is also considered. It is discretized by annular sector element. The rotating spindle which includes the clamp, hub, permanent magnet and yoke, is modeled by Timoshenko beam including the gyroscopic effect. The flexible supporting structure with a complex shape which includes stator core, housing, base plate, sleeve and thrust pad is modeled by using a 4-node tetrahedron element with rotational degrees of freedom to satisfy the geometric compatibility. The dynamic coefficients of HDB are calculated from the HDB analysis program, which solves the perturbed Raynolds equation using FEM. Introducing the virtual nodes and the rigid link constraints defined in the center of HDB, beam elements of the shaft are connected to the solid elements of the sleeve and thrust pad through the spring and damper element. The global matrix equation obtained by assembling the finite element equations of each substructure is transformed to the state-space matrix-vector equation, and the associated eigenvalue problem is solved by using the restarted Arnoldi iteration method. The validity of this research is verified by comparing the numerical results of the natural frequencies with the experimental ones. Also the effect of supporting structures to the natural modes of the total HDD system is rigorously analyzed.

• 열처리공학회지
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• 제27권2호
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• pp.65-71
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• 2014

SMF9060 material is a Fe-based powder sintered alloy that is used for several automobile components such as Synchronize Hub, oil pump and transmission. These components are required excellent wear resistance and durability. In this study, we have performed a dry wear test at the ambient air and Ar gas conditions in the room temperature, and a lubricant wear test at the room temperature and engine oil temperature of $100^{\circ}C$. The amount of wear volume and coefficient friction are measured by a Profilometer and a Ball on disk type wear tester. The wear volume in Ar gas condition was a little higher than that in the ambient air condition. However the wear volume in the lubricant wear condition was much lower than in the dry wear condition. XRD analysis of the debris in Ar gas condition showed that the oxide film was not formed.