• ETRI Journal
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• 제35권3호
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• pp.439-447
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• 2013

To increase device memory yield, many manufacturers use incorporated redundancy to replace faulty cells. In this redundancy technology, the implementation of an effective redundancy analysis (RA) algorithm is essential. Various RA algorithms have been developed to repair faults in memory. However, nearly all of these RA algorithms have low analysis speeds. The more densely compacted the memory is, the more testing and repair time is needed. Even if the analysis speed is very high, the RA algorithm would be useless if it did not have a normalized repair rate of 100%. In addition, when the number of added spares is increased in the memory, then the memory space that must be searched with the RA algorithms can exceed the memory space within the automatic test equipment. A very efficient RA algorithm using simple calculations is proposed in this work so as to minimize both the repair time and memory consumption. In addition, the proposed algorithm generates an optimal solution using a tree-based algorithm in each fault group. Our experiment results show that the proposed RA algorithm is very efficient in terms of speed and repair.

• Communications for Statistical Applications and Methods
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• 제17권6호
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• pp.865-877
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• 2010

본 논문에서는 보증기간이 종료된 이후의 수리가 가능한 시스템에 대한 주기적인 예방보전모형을 고려하는데, 무료수리보증, 비례수리보증 그리고 혼합수리보증과 같은 세 종류의 수리보증정책을 고려한다. 이러한 세 종류의 수리보증기간이 종료된 이후의 수리가 가능한 시스템에 대한 주기적인 예방보전모형에 대하여 각각 기대순환길이, 총기대비용 그리고 단위시간당 기대비용을 유도한다. 또한 유도된 단위시간당 기대 비용을 최소화하는 최적의 예방보전정책인 최적의 예방보전주기와 예방보전횟수를 결정하는 방법에 대하여 설명한다. 끝으로 고장시간이 와이블분포를 하는 경우에 최적의 주기적 예방보전정책을 결정하여 본다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제12권3호
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• pp.266-269
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• 2012

High-efficiency built-in redundancy analysis (BIRA) is presented. The proposed BIRA uses three techniques to achieve a high repair rate using spare mapping registers with adjustable fault tags to reduce area overhead. Simulation results show that the proposed BIRA is a reasonable solution for embedded memories.

• 한국신뢰성학회지:신뢰성응용연구
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• 제12권2호
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• pp.57-66
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• 2012

In this paper, we consider the periodic preventive maintenance model for a repairable system following the expiration of replacement-repair warranty. Under this preventive maintenance model, we derive the expressions for the expected cycle length, the expected total cost and the expected cost rate per unit time. Also, we determine the optimal preventive maintenance period and the optimal preventive maintenance number by minimizing the expected cost rate per unit time. Finally, the optimal periodic preventive maintenance policy is given for Weibull distribution case.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.390-395
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• 2002

The experimental and numerical study has been conducted on the sleeve repair welding of API 5L X65 pipeline. SMA W and GTAW were applied to weld the sleeve. The macrostructure and hardness of repair welds have been examined. The [mite element analysis of the multi-pass sleeve-fillet welding has been conducted to validate the experiment and investigate the effects of in-service welding conditions. The effect of gas flow rate on the hydrogen cracking was investigated. The effect of internal pressure on residual stresses and plastic strain was investigated. The allowable heat input was predicted considering the maximum temperature of inner surface of pipe and cooling rate at CGHAZ.

• International Journal of Korean Welding Society
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• 제2권2호
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• pp.36-41
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• 2002

The experimental and numerical study has been conducted on the sleeve repair welding of API 5L X65 pipeline. SMAW and GTAW were applied to weld the sleeve. The macrostructure and hardness of repair welds have been examined. The finite element analysis of the multi-pass sleeve-fillet welding has been conducted to validate the experiment and investigate the effects of in-service welding conditions. The effect of gas flow rate on the hydrogen cracking was investigated. The effect of internal pressure on residual stresses and plastic strain was investigated. The allowable heat input was predicted considering the maximum temperature of inner surface of pipe and cooling rate at CGHAZ.

• 품질경영학회지
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• 제28권3호
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• pp.53-58
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• 2000

In many cases, it is more practical and economical to repair a system than to replace the whole system or to perform a complete overhaul when it fails. The age replacement policy with minimal repair at failure is considered. The system is replaced every time its age reaches at $T_0$. For each intervening failure only minimal repair is done. The minimal repair times in a renewal period are increasing in the sense that the minimal repair times constitute a strictly increasing geometric process. The long-run expected cost rate Is obtained and the properties of the existence and the uniqueness of the optimal policy minimizing the long-run expected cost rate are derived.

• International Journal of Reliability and Applications
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• 제18권1호
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• pp.1-8
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• 2017

In this paper, we study an extended warranty model under minimal repair-replacement warranty (MRRW) which is suggested by Park, Jung and Park (2013). Under MRRW policy, the manufacturer is responsible for providing the minimal repair-replacement services upon the system failures during the warranty period. And if the failure occurs during the extended warranty period, only the minimal repair is conducted. Following the expiration of extended warranty, the user is solely responsible for maintaining the system for a fixed length of time period and replaces the system at the end of such a maintenance period. During the maintenance period, only the minimally repair is given for each system failure. The main purpose of this article is to suggest the extended warranty and replacement model with MRRW. Given the cost structures incurred during the life cycle of the system, we formulate the expected cost and the expected length of life cycle to obtain the expected cost rate.

• 대한안전경영과학회지
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• 제3권4호
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• pp.91-101
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• 2001

This paper is to develop replacement models under minimal repair with exponential polynomial wavelet failure rate function. Wavelets have good time-frequency localization, fast algorithms and parsimonious representation. Also this study is presented along with numerical examples using sensitivity analysis for exponential polynomial trigonometric failure rate function.

• 한국도로학회논문집
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• 제15권6호
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• pp.49-60
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• 2013

PURPOSES : The evaluation of the pavement condition of the asphalt concrete pavement of No. 2 runway of Inchon International Airport through PMS, a supporting system for making a decision of pavement, maintenance and repair, was made, and the proper time for repair according to the PCI reduction rate was suggested. METHODS : By comparing and analyzing the evaluation results of pavements built in 2009, 2010, 2011, PCI change in each facility (No. 2 runway, C parallel taxiway, connection taxiway) was calculated. By applying the calculated change to PCI deduction rate model, the pavement condition of the target sections was estimated, and then the necessary section and time for repair were chosen. RESULTS : After careful consideration of the time for pavement and maintenance, based on the result of PCI prediction, it was estimated that the southern takeoff and landing section of No. 2 runway was required to be repaired in 2012; connection taxiway in 2013; and C parallel taxiway in 2014; however, the section which is the main moving route of connection taxiway and C parallel taxiway was needed to be repaired in 2012. CONCLUSIONS : For maintenance and repair of airport pavements, the optimal alternative should be chosen by considering economics and operability, via examining the time for repair and the aspect of management all together on the basis of this study.