• Proceedings of the Korean Society for Quality Management Conference
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• 2006.11a
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• pp.105-109
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• 2006

MTTR and MTBSF are two representative quantitative maintainability and reliability requirements for railway systems. we deal with the redundancy allocation problem to satisfy the two requirements. The redundancy increases MTBSF and changes MTTR. Parallel redundancy and the exponential lifetime distribution of components are considered for the series systems. Mathematical model and example are presented for the redundancy optimization problem of minimizing the cost subjecting to MTTR and MTBSF requirements.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.2
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• pp.157-164
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• 2012

When designing a multifunctional system consisting of many components performing many functions or missions, it is important to determine the reliability, availability, and maintainability (RAM) of the system and components, and we consider system availability to be the optimization criterion. For given intervals of mean time between failure (MTBF) and mean time to repair (MTTR) of the components, we want to determine the values of MTBF and MTTR for all components that satisfy the target availability. A heuristic method is proposed for finding near-optimal solutions through simulation. We also study numerical examples to check effects of model parameters on the optimal solutions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3444-3449
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• 2013

The control module controlling points has become high-tech. but the introduction of relevant company's inspection intervals and methods, and the adoption of the way which is used in relay interlock system became the cause of a failure by excessive and incorrect maintenance. The Human error in failure recovery process can cause vital accidents including train derailment, the points monitoring system could prevent this problem by monitoring points' operation condition in real time. After conducting the changed inspection intervals that applied the results of the criticality of each failure type, MTBF, MTTR, availability, maintainer's opinion, the work became simplified, and, the failure did not occur for 4 consecutive years in contrast to the previous annual average of 11 failures.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1989-1992
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• 2009

Maintenance is classified preventive maintenance before performing equipment failure and corrective maintenance after performing equipment failure. In preventive maintenance, we may analyze the failure data to end from beginning of equipment and allocate maintenance method and calculate maintenance cycle quantitatively by the failure data analysis. So, it has a merit to reduce system maintenance cost and to operate effectively but, it require high cost in system introducing and continuous operation to end of system. In corrective maintenance, we may calculate MTTR(mean time to repair) quantitatively based on function failure time. it can be based on establishing maintenance system for operation efficiency. In this paper, we may reflect the MTTR for the onboard equipped in Tilting train to establish maintenance system for Tilting train operation efficiency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4762-4767
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• 2012

The AF track circuit that detecting train position and transmitting various train control data for DTG to the train on-board is composed of single operation system. If a failure occurs on this system, the driver should be operate the train by manually until the system is restored, because the system cannot control switch machines and signals by automatically. In this process the human error affects to the train delay, collision, derailment and critical safety accident. Therefore, this document has analyzed the effects that each failure mode influences on system and train, and quantified the failure valuation point and class. Basis on this quantified analysis result, MTBF increased and MTTR decreased and failure number also decreased by adopting the independent installation of power supply, the replacement of defected capacitors, the installation of resister cooling system and the improvement of maintenance methods. And the failure factors of AF track circuits were decreased by conducting the preventive maintenance which is a quantitative way of maintenance system by experience.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.247-250
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• 2018

The remote diagnostic system has been developed for enhancing operability of Data Service Platform(DSP) of Korean e-Navigation Project performed by Ministry of Oceans and Fisheries(MOF) since 2016. It plays a critical role to find and handling logical, physical error in early time in order to maximize operability of DSP, which makes DSP to provide seamless service to various ships voyaging in the sea. Therefore, as developing a system to diagnose resource and operation status of DSP immediately in a remote place, and a system to feed it back to operator or to recover it on its own, DSP can have short period of MTTR as well as high chance of providing proper service to ships in voyage.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.6
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• pp.824-831
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• 2019

For effective development in consideration of the maintainability of the weapon system, it is necessary to understand whether the maintainability design requirements are satisfied at the early phase of development. This requires the application of an early design phase maintainability prediction process to provide opportunities for improvement. By defining the ambiguity group definition, fault isolation level, fault isolation probability, and countermeasures for faults, it was possible to predict early phase development. The MTTR of the initial design phase applying Procedure V to the artillery system was 3.46H, which is about 16 % higher than 2.98H, the MTTR using Procedure II. This is a result of system design ambiguity that has not been specified in the early phase of development.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.247-254
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• 2019

Recently, in designing military equipment, considerable attention has been paid to maintaining operations, including reliability, maintenance, and maintenance time of equipment, from the early stages of development. Therefore, both users and developers stress the importance of design considering the maintenance time. This study evaluated the specific methodologies for predicting the realistic maintenance time, such as the access complexity of equipment, other than the standard maintenance time provided by the conventional method mil-hdbk-470a at the beginning of the design, and applied the time conversion factor using a measure of the maintenance complexity. In addition, the actual maintenance time reflecting the actual maintenance time of the developed equipment and the time-conversion factor applied was compared/verified to confirm the reliability of the data. In a study to set a target for repair and the repair of equipment design in the future, it is expected that the maintenance time of equipment that fails to measure the maintenance time for the initial actual equipment will be reflected as a more realistic time. Moreover, activities, such as research and design reflection activities, will be performed to reduce the maintenance time, operational maintenance cost, etc.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.927-932
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• 2005

전투기를 적절히 정비하는 활동은 공군력을 유지하는데 중요하다. 일반적인 정비정책은 정해진 일정으로 주요 모듈의 정비를 수행한다. 그러나, 이러한 정비활동은 시간에 따라 변하는 모듈의 특성을 반영할 수 없다. 이에 본 연구는 변동되는 평균 고장간 시간 (MTBF) 과 평균 수리 시간 (MTTR)을 산출할 수 있는 확률효과회귀모형을 이용하여 시간에 따라 변동되는 모듈의 특성을 반영한 동적 예방정비 주기를 예측하고자 한다. 본 연구의 결과는 대한민국 공군의 전투 준비 태세 향상에 이바지 할 것으로 기대된다.

• IE interfaces
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• v.11 no.1
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• pp.175-182
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• 1998

The maintainability prediction of an underwater military system is considered. A general and parctical prediction method for maintainability using MIL-HDBK-472 is presented. We develop a computer program to predict MTTR of an underwater military system. A case study is made to explain the proposed maintainability prediction method.