• Korean Journal of Computational Design and Engineering
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• v.19 no.3
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• pp.203-213
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• 2014

The O&M (Operation and Maintenance) phase of offshore plants with a long life cycle requires heavy charges and more efforts than the construction phase, and the occurrence of an accident of an offshore plant causes catastrophic damage. So previous studies have focused on design for reliability, and recently many studies have dealt with a maintenance system to prevent unexpected failures. Nowadays due to the emerging ICTs (Information Communication Technologies) and sensor technologies, it is possible to send health monitoring information of important equipment to administrator of an offshore plant in real time, which leads to having much concern on condition based maintenance policy or predictive maintenance. In this study, we have reviewed previous studies associated with condition-based maintenance of offshore plants, and introduced the approaches predicting failures of the compressor which is one of essential mechanical devices in LNG FPSO.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.474-479
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• 2005

For the safe operation of an air conditioner, the liquid car η 'over to compressors should be minimized and compressors should be operated in the specified region of suction and discharge pressures recommended by compressor manufactures. In this study, a capillary assisted tandem-type airconditioner was considered. A variable speed outdoor fan was used to control operating points of the system. Test results showed the possibilities to move system operating points to the safe region by controlling the speed of an outdoor fan.

• Tribology and Lubricants
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• v.14 no.2
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• pp.75-81
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• 1998

Condition monitoring technology was applied for an air compressor lubricating system to achieve a proactive maintenance, which could prevent a catastrophic failure and detect root causes of the conditional failure of the system. For this work, various types of wear monitoring technology were used and compared with the results of vibration and temperature measurements. The Results generally showed that every technology has a limitation to failure detection, and integrated-based condition monitoring should be performed for the best results. In this work, an idea for the implementing integrated wear monitoring was suggested and demonstrated.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.191-199
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• 1997

Condition monitoring technology was applied for an air compressor lubricating system to achieve a proactive maintenance, which could prevent a catastrophic failure and detect root causes of the conditional failure of the system. For this work, various types of wear monitoring technology were used and compared with the results of vibration and temperature measurements. Results generally showed that every technology has a limitation to failure detection, and integrated-based condition monitoring should be performed for the best results. In this work, an idea for the implementing integrated wear monitoring was suggested and demonstrated.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.139-144
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• 2003

This study was aimed to establish failure management plan of the rubber-tired AGT light rail vehicle for its safety case, which was developed according to the Korean standardized specifications for the light rail vehicle. Vehicular 9 failure modes anticipated during the system operation were considered, which are single malfunction of redundant equipment, malfunction of train radio, public address and air compressor, battery, main circuit NFB trip, on-board ATO control device malfunction, on-board ATP control device malfunction, fail of brake release, flat tire, train emergency door open.

• Journal of Applied Reliability
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• v.11 no.2
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• pp.111-126
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• 2011

The clutch coil mounted on the automotive air conditioner is an important part which actuates the clutch to connect or disconnect the pulley and the compressor according to the climate control condition in an automobile. Here, it is generally required that the clutch coil should ensure the long term durability requirement, such as a warranty for the 10 years of field operation or 160,000 km driving, especially in a brand new item, and so forth. However, some difficulties have arisen in restoring its credibility, since domestic specifications for the part have not been yet unified. In order to ensure the reliability, test methods and assessment criteria should be standardized. Moreover, assessed lifetime under specific conditions and potential failure analysis would be important. In this study, lifetime test specifications for the clutch coil have been reviewed and methodological suggestions are provided to ensure reliability, utilizing a quality function deployment through the potential failure mode effect analysis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.3
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• pp.411-416
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• 2015

This paper presents the thermal modeling and analysis of Line power Start Permanent magnet Motor (LSPM). Thermal analysis of electrical machines is important because temperatures that are consistently too high will reduce the life time of machines and may lead to serious failure. Coefficients of convection are calculated according to the types of operating conditions. And computational fluid dynamics (CFD) technique is performed in order to predict thermal characteristic. The results are compared to the test results.

• International Journal of Safety
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• v.8 no.1
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• pp.6-9
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• 2009

The crack in a J85 engine V.G. actuator arm shaft for a bell crank on the engine compressor was investigated. The crack was observed in twenty two shafts during the inspection of 238 shafts. The failure analysis of shaft cracks was performed by chemical composition analysis using ICP(Inductively Coupled Plasma) and by fracture surface and microstructure analysis using FE-SEM and optical microscope. The crack initiated from the top and bottom and propagated to the center along the grain boundaries. From the chemical composition analysis, the fractography of the fracture surface and the microstructure, it was found that the failure mechanism of the shafts is the inclusion-related intergranular decohesion crack. The inclusion was found out from MnS particle by EDS(Energy Dispersive Spectroscopy). The crack initiated MnS inclusion in the grain boundary and propagated with the increase of applied shear stress during long operation. In order to prevent the fracture, NDI(Nondestructive inspection) is needed periodically as recommended.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.324-327
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• 2003

The needs for the cryocooler which has high reliability and long MTTF are increased in the military and commercial thermal imaging system The gas contamination wear, leakage of the working fluid, fatigue and etc. have the significant effects on the reliability and MTTF(Mean Time To Failure) or MTBF(Mean Time Between Failure) of the Stirling cryocooler. In the KIMM, the Stilting cryocooler with the linear compressor was released after the several performance tests were performed. This paper describe the experimental facility for the MTTF evaluation and some typical results of the Stilling cryocooler.

• Journal of Mechanical Science and Technology
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• v.18 no.9
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• pp.1537-1548
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• 2004

This paper presents a novel diagnostic technique for monitoring the system conditions and detecting failure modes and precursors based on wavelet-packet analysis of external noise/vibration measurements. The capability is based on extracting relevant features of noise/vibration data that best discriminate systems with different noise/vibration signatures by analyzing external measurements of noise/vibration in the time-frequency domain. By virtue of their localized nature both in time and frequency, the identified features help to reveal faults at the level of components in a mechanical system in addition to the existence of certain faults. A prima-facie case is made via application of the proposed approach to fault detection in scroll and rotary compressors, although the methods and algorithms are very general in nature. The proposed technique has successfully identified the existence of specific faults in the scroll and rotary compressors. In addition, its capability of tracking the severity of specific faults in the rotary compressors indicates that the technique has a potential to be used as a prognostic tool.