• Tribology and Lubricants
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• 제22권4호
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• pp.196-202
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• 2006

This paper presents a case study on the tribological failure analysis of a clutch system for a manual transmission car. The clutch systems are composed of clutch disk, clutch pressure plate, flywheel rubbing surface, coil and diaphragm springs, release bearing and lever, clutch spline and shaft. The purpose of a clutch system is to transmit and disconnect the driving power of engines by frictional farce from a rubbing surface of a flywheel to a clutch disk and clutch pressure plate with a minimum power loss. In this study, many tribological failure cases based on the wear phenomena and thermal distortions have been presented, which are collected from the car repair shop and maintenance center. The triboiogicai failures are mostly come from the driving conditions, overloading of a car, and especially driving style and personal habit of a car driver.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제29회 춘계학술대회
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• pp.53-60
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• 1999

As the flying height decreased, it is essential that hard disk drives perform reliable under various environmental conditions. In this paper the tribological characteristics of a head/disk interface are investigated under various temperature, relative humidity, altitude and outgas conditions. Specially, Contact-Start-Stop(CSS) tests were performed to assess the stiction, acoustic emission, slider take-off behavior, and track average amplitude(TAA). It is shown that the surface damage and head failure are accelerated by high temperature and humidity as well as low ambient pressure.

• 한국소음진동공학회논문집
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• 제16권9호
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• pp.982-989
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• 2006

The centrifugal force acting on a rotating disk creates the in-plane loads in radial and circumferential directions. Application of fiber reinforced composite materials to the rotating disk can satisfy the demand for the increment of its rotating speed. However, the existing researches have been confined to lamina disks. This paper deals with the stress and vibration analysis of rotating laminated composite disks. The maximum strain theory for failure criterion is applied to determine the strength of the laminate disk from which the maximum allowable speed is obtained. Dynamic equation is formulated in order to calculate the natural frequency and critical speed for rotating laminated disks. The Galerkin method is applied to obtain the series solution. The numerical results are given for the cross-ply laminated composite disks.

• Journal of Mechanical Science and Technology
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• 제14권7호
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• pp.744-751
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• 2000

To achieve lower flying height for high areal recording density, the laser zone texturing of the disk needs to be designed to reduce glide height. One problem of the laser bump design is that the regular laser bump pattern often produces glide resonance phenomenon, which leads to failure of the glide height test. However, it was found in this study that glide resonance is an intrinsic problem of the glide head used and resonance phenomenon depends on the type of the head slider, that is, the natural frequency of the slider body. Therefore, higher glide height or glide failure caused by glide resonance does not lead to head/media interface problem in the real drive operating conditions in which the data head is used. Pseudo-random bump pattern greatly reduces the glide resonance. Smaller bump pitch will also help to reduce the glide resonance. However, as bump spacing becomes smaller, glide height will be increased due to increased air pressure developed around the bumps. Lowering bump height is the most effect way to reduce glide avalanche.

• 한국정보과학회논문지:시스템및이론
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• 제27권7호
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• pp.675-683
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• 2000

실시간 멀티미디어 응용 서비스를 위해 저장 시스템은 성능 저하 없이 데이타를 제공하여야 한다. 단일디스크 고장시 빠른 데이타 복구는 상당히 중요하므로 디스크 복구 장치가 필요하다. RAID 레벨 5 에서 단일디스크 고장시 새 디스크가 교체되기 전까지 유발되는 급격한 성능저하를 방지할 수 있는 혼합형 복구 기법을 제안한다. 이 기법은 기존 연구에서 제시된 예비 디스크 기법에 비해 추가 디스크를 사용하지 않으므로 경제적이다. 제안한 기법의 성능은 여러 가지 요구크기에 대해 RAID 레벨 5 성능과 시뮬레이션을 통하여 비교한다. 시뮬레이션 결과 제안한 기법은 실패모드에서는 20%， 재구성모드에서는 80%이상의 성능 개선을 보인다. 그리고, RAID 컨트롤러와 하드디스크를 사용해 멀티미디어 서버 시스템을 구축하여 시뮬레이션 결과를 비교한다.

• 한국정보처리학회논문지
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• 제3권7호
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• pp.1917-1923
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• 1996

대량의 데이터를 저장하는 시스템은 다중디스크 시스템이 필수적이다. 그러나 디스 크의 갯수가 늘어나면 디스크시스템의 신뢰성이 떨어진다. 디스크시스템을 구성하는 디스크 중 하나의 디스크가 고장났을 경우에는 정상 동작하지만, 두 개이상의 디스 크가 고장일 경우에는 저장된 데이타를 잃게되는 디스크시스템을 고려하였다. 또한 각 디스크의 수명은 서로 다른 매개변수를 갖는 지수분포를 따르며, 수리시간은 일반 적인 확률분포를 갖는다고 가정한다. 이 가정을 바탕으로 하여 주어진 디스크시스템의 신뢰성을 MTTF(Mean Time To Failure)로서 분석 하였다. 그리고 디스크시스템의 설계에 필요한 파라미터를 도출하였으며, 특별한 경우 대하여 선형비용 구조하에서 디스크시 스템의 수명을 주어진 값보다 크게 하는 최소 비용 문제를 고찰하였다.

• 디지털콘텐츠학회 논문지
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• 제15권2호
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• pp.301-308
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• 2014

최근에 데이터가 대용량화됨에 따라 정보 저장의 중요성이 부각되고 있다. 본 연구는 대용량 저장장 치에 많이 사용되는 2.5인치 HDD에 대해서 가속 시험결과를 토대로 연간 제품 고장률을 예측하고 사용 환경에 대한 연간 제품 고장률과의 차이를 최소화 시키는 새로운 방안을 제시하고자 한다. 반품된 2.5인치 HDD 309개의 정보를 분석하여 실사용 환경의 시간당 전송량을 구했고, 가속 수명시험으로부터 가속 시험조건의 시간당 전송량을 구한 후, 사용률에 대한 가속 계수를 산출했다. 온도에 대한 가속 계수, 사용률에 대한 가속 계수와 고장률로 연간 제품 고장률을 예측하였다. 가속 시험의 시간당 전송량 81.4GB/hour와 사용자 93.4 %까지 대표하는 실사용 환경의 시간당 전송량은 5.8 GB/hour로 산출한 사용률에 대한 가속 계수는 14.1이다. 실사용 환경의 연간 제품 고장률은 1년 이후 안정화 되었으며, 이때 연간 제품 고장률은 0.3~0.378 % 이내에서 변동 하였다. 본 연구를 통하여 예측된 연간 제품 고장률은 0.4 %로 실사용 환경의 연간 제품 고장률과 75~94%의 일치됨을 보였다. 본 연구는 제조사의 가속수명 결과로 실사용 환경을 연간 제품 고장률을 예측하는 방법에 영향을 줄 것이다.

• Tribology and Lubricants
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• 제27권5호
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• pp.269-274
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• 2011

The purpose of this paper is to study and analyze the improvement method for the failure examples including the vehicle brake system in actual field. It was verified that the indicator plate of pad wear scratched the brake disk because of wearing after displacement of non- identification parts pad. The caliper of other vehicle was installed with brake system verified the phenomenon produced groove in center point because of one side wear when the pad was not fully contacted with the rub disk by other action surface pressure and pad action condition. It verified that the crack phenomenon fatigue was produced by brake thermal deformation because of decreasing the thickness by grinding to modify the non-uniformed wear of brake disk. It verified that the friction sound was produced by the friction phenomenon because of non-uniformed contact of lining and an alien substance with inner of the drum and lining braking by crack phenomenon with brake drum surface.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.147-152
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• 2000

This paper presents the thermoelastic analysis and 3-D failure analysis of the carbon/carbon brake disk. The mechanical properties of the carbon/carbon brake disk were measured for both in-plane and out of plane directions. The mechanical properties were used as the input of the thermoelastic analysis and 3-D stress analysis for the brake disk. The gap between rotor clip and clip retainer was an important parameter in the loading transfer mechanism of the rotor. The change of gap was considered separating the mechanical deformation and thermal deformation. Because the rotor clip and clip retainers were not contacted, the clip retainers and rivets were excluded from the rotor analysis model. The disk was modeled by using the cyclic symmetry condition and the contact problem between the rotor disk and rotor clip was considered. From the results of the 3-D stress analysis, the stress concentration at the key hole of the brake disk was confirmed.

• 한국정밀공학회지
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• 제21권5호
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• pp.122-130
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• 2004

In a high-speed and wide operating field optical disk drive, the vibration problem is one of the most important factors to be considered for reliable performance. And a disk misaligned with axis of rotation is a major source of vibration in optical disk drive. Furthermore, this vibration disturbance of the disk spindle system causes failure in the reading and writing process. So to solve this vibration problem, the vibration absorber using rubber mount has been introduced in recent years. In this paper, we have analyzed the simple optical disk drive model with dynamic vibration absorber through dynamic analysis of 12-dof by Recurdyn program and obtained optimal mass and frequency ratios of dynamic vibration absorber of dynamic vibration absorber and the optimal frequency ratio.