• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.203-210
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• 2005

Prototype model of MDU(Master Data Unit), to be employed on KSLV-I, has been developed and tested being interfaced with other units. Before stepping into the development of engineering and flight model phases, we have carried out reliability prediction of prototype MDU in order to assure availability of the unit. This paper describes the method of reliability prediction of prototype MDU and prediction results based on MIL-HDBK-217F, 'Electronic Reliability Design Handbook'.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.4
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• pp.142-148
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• 2015

Due to advancements in technology and manufacturing capability, it is not uncommon that life tests yield no or few failures at low stress levels. In these situations it is difficult to analyse lifetime data and make meaningful inferences about product or system reliability. For some products or systems whose performance characteristics degrade over time, a failure is said to have occurred when a performance characteristic crosses a critical threshold. The measurements of the degradation characteristic contain much useful and credible information about product or system reliability. Degradation measurements of the performance characteristics of an unfailed unit at different times can directly relate reliability measures to physical characteristics. Reliability prediction based on physical performance measures can be an efficient and alternative method to estimate for some highly reliable parts or systems. If the degradation process and the distance between the last measurement and a specified threshold can be established, the remaining useful life is predicted in advance. In turn, this prediction leads to just in time maintenance decision to protect systems. In this paper, we describe techniques for mapping product or system which has degrading performance parameter to the associated classical reliability measures in the performance domain. This paper described a general modeling and analysis procedure for reliability prediction based on one dominant degradation performance characteristic considering pseudo degradation performance life trend model. This pseudo degradation trend model is based on probability modeling of a failure mechanism degradation trend and comparison of a projected distribution to pre-defined critical soft failure point in time or cycle.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.1
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• pp.566-576
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• 2018

As the weapon systems of the Korean Army possess massive firepower and multiple functions, the improvement of their quality through reliability prediction is becoming increasingly important. Currently, the reliability prediction of the weapon systems of the Korean Army is a difficult process, because it is conducted by naively calculating the reliability of their constituent parts. Recently, as various studies using accumulated data are undertaken across various industries, the defense industry is also attempting to analyze the Dark Data which have been accumulated but not yet used. Therefore, it is necessary to apply Post-Logistics Support (PLS) data in order to improve the reliability of the weapon systems and, for this purpose, the Korean Army needs to conduct diverse studies. Especially, the PLS data in the defense industry is very useful for reliability prediction, because the data on the defects reported after the development of the weapon systems are accumulated in this phase. This study examines the existing reliability prediction method conducted using the component parts and proposes a new reliability prediction method using PLS data. This framework can ultimately contribute to improve the prediction accuracy and quality of the weapon systems.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1327-1335
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• 2011

Recently, also in railway vehicles, related products are being designed and manufactured through RAMS activities in order to secure their reliability, availability, maintainability & safety. Subway operators are conducting R&D on various preventive maintenance methods and applying them to the field so as to establish a reliability centered maintenance(RCM) system. In this connection, manufacturers shall carry out R&D based on reliability from the first design stage of development to provide high quality products to subway operators. And operators shall have the products operated properly to their particular operating environment and managed based on the standard maintenance manual. Not only that, but the related field data shall be fed back into the manufacturers to upgrade upcoming products by organic cooperation between manufacturer and operators. However, the mutually beneficial cooperative relationship is not still developed in the domestic railway industry. In terms of methodology for life prediction, this study was intended to analyze field data on relays used for rolling stocks considering operational characteristics in the position of subway operators and predict parts reliability using reliability prediction program from the standpoint of manufacturers as well.

• Journal of Applied Reliability
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• v.10 no.3
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• pp.171-182
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• 2010

The reliability prediction analysis is a feedback tool that designer uses to provide insight into the component designs. This insight may indicate sensitive components within the design. This paper examines predicted failure rates for hybrid dc-dc converter for spacecraft using MIL-HDBK-217F prediction methodology. The results from part count/stress analysis represent priority components that affect the converter failures. The high priority components are analyzed to find out stress factor based on MIL-HDBK-217F. This information provides an opportunity for designer to improve the reliability of the product in development process.

• Journal of Applied Reliability
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• v.7 no.1
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• pp.31-43
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• 2007

The function of O-ring seals is to prevent leakage during the service life of the components in which they are installed. The life prediction of O-ring is very important at various industry fields. Generally, to evaluated the long-term performance of O-ring in severe environments has applied a life prediction technique based on accelerated life test (ALT). In this work, Accelerated thermal aging test(l20, 130, 140, $150^{\circ}C$) of O-ring was applied for life prediction of O-ring. The property changes after thermal aging test was measured using TGA, DSC, FT - IR, Video Microscope and SEM. Shape parameter and life prediction were obtained using MINITAB program.

• Journal of Applied Reliability
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• v.17 no.4
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• pp.296-304
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• 2017

Purpose: Recent weapon systems in defense have increased the complexity and importance of software when developing multifunctional equipment. In this study, we analyze the accuracy of the proposed software reliability model when applied to weapon systems. Methods: Determine the similarity between software reliability analysis results (prediction/estimation) utilizing data from developing weapon systems and system failures data during operation of weapon systems. Results: In case of a software reliability prediction model, the predicted failure rate was higher than the actual failure rate, and the estimation model was consistent with actual failure history data. Conclusion: The software prediction model needs to adjust the variables that are appropriate for the domestic weapon system environment. As the reliability of software is increasingly important in the defense industry, continuous efforts are needed to ensure accurate reliability analysis in the development of weapon systems.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.1
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• pp.31-36
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• 2010

Collecting all failures during life cycle of vehicle is not easy way because its life cycle is normally over 10 years. Warranty period can help gathering failures data because most customers try to repair its failures during warranty period even though small failures. This warranty data, which means failures during warranty period, can be a good resource to predict initial reliability and permanence reliability. However uncertainty regarding reliability prediction remains because this data is censored. University of Wuppertal and major auto supplier developed the reliability prognosis model considering censored data and this model introduce to predict reliability estimate further "failure candidate". This paper predicts reliability of telecommunications system in vehicle using the model and describes data structure for reliability prediction.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.24 no.4
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• pp.26-34
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• 2016

In this study, reliability prediction of the ignition system of hybrid rocket is performed. The FMECA is preceded to the reliability prediction. To this end, the ignition system is divided into 5 components and 19 potential failure modes. The failure cause and effects are identified and criticality analysis is carried out for each failure mode, in which the criticality number is estimated using the failure rate databases. Among the numbers, the failure modes and components with higher criticality and severity are chosen and allocated with higher weighting factor. The reliability predictions are performed using the failure rate databases, from which the current ignition system is found to satisfy the target reliability.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.2
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• pp.1-4
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• 2015

Qualification includes all activities to demonstrate that a product meets and exceeds the reliability goals. Manufacturers need to spend time and resources for the qualification processes under the pressure of reducing time to market, as well as offering a competitive price. Failure to qualify a product could result in economic loss such as warranty and recall claims and the manufacturer could lose the reputation in the market. In order to provide valid and reliable qualification results, manufacturers are required to make extra effort based on the operational and environmental characteristics of the product. This paper discusses optimal interval censoring design for reliability prediction of electronic packages under limited time and resources. This design should provide more accurate assessment of package capability and thus deliver better reliability prediction.