Reliability Assessment of Distribution Network Considering Mobile Energy Storage Vehicles and Dynamic Zonal Coupling

Yang Wei,Wang Dan,Guo Jingming,Zhang Yijiao,Zhang Jiajia,Bian Zhaoyuan 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.1

Mobile energy storage spatially and temporally transports electric energy and has fexible dispatching, and it has the potential to improve the reliability of distribution networks. In this paper, we studied the reliability assessment of the distribution network with power exchange from mobile energy storage units, considering the coupling diferences among diferent time and zones of the vehicle–road–network system. First, we constructed a basic mobile energy storage operation framework that supports the distribution network reliability. Next, we proposed a quantitative model to describe the dynamic zonal coupled vehicle–road–network system. Based on this model, the corresponding charging and discharging scheduling strategies for diferent mobile energy storage units are well designed to improve the efciency of power support. Then, we provided a distribution network reliability assessment algorithm handling the power exchange from mobile energy storage units. Finally, we used the IEEE 33-node example system to clarify the necessity of the vehicle–road–network model in accounting for dynamic zonal coupling. We also analyzed the impact of diferent characteristics of mobile energy storage on the reliability of the distribution network, and verifed that one can improve the distribution network reliability by increasing the response speed, power capacity, or charging/discharging power of mobile energy storage vehicles.

Reliability and availability assessment of seabed storage tanks using fault tree analysis

Choi, I.H.,Chang, D. Pergamon Press 2016 Ocean engineering Vol.120 No.-

This study proposes the concept of subsea production systems with a seabed storage tank to provide an alternative to conventional floating facilities and performs the reliability, maintainability and availability study for the seabed storage tank. The reliability assessment of the seabed storage tank performs a four-step procedure. A four-step procedure is to define the system boundary, collect the reliability data, construct a fault tree and estimate the reliability. The failure and repair data are obtained from the component of the lowest level of the seabed storage tank because the seabed storage tank is a new system unknown reliability data. Reliability of the seabed storage tank is estimated with a consideration of critical events. The total failure frequency of the SST is estimated approximately 2.27. 10<SUP>-4</SUP>/hour. The maintainability analysis is estimated in accordance with MIL-HDBK 472 Procedure V. The elements of repair time is obtained from the subsea JIP 2000 and RAM study of field data. Active repair time from OREDA 2009 is regarded as the repair/replace of repair time elements. The total repair time is mainly effected by the preparation time of repair time elements. The system availability for the seabed storage tank under normal operation is calculated as approximately 91.8%.

목표 신뢰도를 고려한 원-샷 시스템의 최적검사정책

정승우,정영배 한국산업경영시스템학회 2017 한국산업경영시스템학회지 Vol.40 No.4

A one-shot system (device) refers to a system that is stored for a long period of time and is then disposed of after a single mission because it is accompanied by a chemical reaction or physical destruction when it operates, such as shells, munitions in a defense weapon system and automobile airbags. Because these systems are primarily related with safety and life, it is required to maintain a high level of storage reliability. Storage reliability is the probability that the system will operate at a particular point in time after storage. Since the stored one-shot system can be confirmed only through inspection, periodic inspection and maintenance should be performed to maintain a high level of storage reliability. Since the one-shot system is characterized by a large loss in the event of a failure, it is necessary to determine an appropriate inspection period to maintain the storage reliability above the reliability goal. In this study, we propose an optimal inspection policy that minimizes the total cost while exceeding the reliability goal that the storage reliability is set in advance for the one-shot system in which periodic inspections are performed. We assume that the failure time is the Weibull distribution. And the cost model is presented considering the existing storage reliability model by Martinez and Kim et al. The cost components to be included in the cost model are the cost of inspection c1, the cost of loss per unit time between failure and detection c2, the cost of minimum repair of the detected breakdown of units c3, and the overhaul cost c4 of Rs ≤ Rg. And in this paper, we will determine the optimal inspection policy to find the inspection period and number of tests that minimize the expected cost per unit time from the finite lifetime to the overhaul. Compare them through numerical examples.

Optimal Inspection Policy for One-Shot Systems Considering Reliability Goal

Seung-Woo Jeong(정승우),Young-Bae Chung(정영배) 한국산업경영시스템학회 2017 한국산업경영시스템학회지 Vol.40 No.4

A one-shot system (device) refers to a system that is stored for a long period of time and is then disposed of after a single mission because it is accompanied by a chemical reaction or physical destruction when it operates, such as shells, munitions in a defense weapon system and automobile airbags. Because these systems are primarily related with safety and life, it is required to maintain a high level of storage reliability. Storage reliability is the probability that the system will operate at a particular point in time after storage. Since the stored one-shot system can be confirmed only through inspection, periodic inspection and maintenance should be performed to maintain a high level of storage reliability. Since the one-shot system is characterized by a large loss in the event of a failure, it is necessary to determine an appropriate inspection period to maintain the storage reliability above the reliability goal. In this study, we propose an optimal inspection policy that minimizes the total cost while exceeding the reliability goal that the storage reliability is set in advance for the one-shot system in which periodic inspections are performed. We assume that the failure time is the Weibull distribution. And the cost model is presented considering the existing storage reliability model by Martinez and Kim et al. The cost components to be included in the cost model are the cost of inspection c1 , the cost of loss per unit time between failure and detection c2 , the cost of minimum repair of the detected breakdown of units c3 , and the overhaul cost c4 of Rs ≤ Rg. And in this paper, we will determine the optimal inspection policy to find the inspection period and number of tests that minimize the expected cost per unit time from the finite lifetime to the overhaul. Compare them through numerical examples.

설계신뢰도 및 정기검사주기가 저장신뢰도에 미치는영향에 관한 연구 : 일회성 군수장비 시스템을 대상으로

추연원 한국융합학회 2018 한국융합학회논문지 Vol.9 No.7

장시간 저장되어 있다가 사용되는 일회성 군수장비 시스템의 경우, 저장 시간이 지남에 따라 저장신뢰도에 변화가 발생하게 된다. 이에 사용시점이 도래하였을 때 제품 사용에 있어 저장신뢰도가 중요한 품질특성으로 작용하게 되며, 기존의 연구들은 저장신뢰도 향상을 위하여 최적의 정기검사주기 산출을 위한 연구에 초점이 맞춰져 있었다. 본 연구에서는 정기검사주기 뿐 아니라 설계신뢰도를 포함한 분석을 통해 융합적인 관점에서 저장신뢰도에 두 인자가 얼마나 영향을 미치는지 분석을 수행하였다. 이를 위해 일회성 시스템의 대표적인 제품인 유도탄에 기존의 Martinez 저장신뢰도 결정모델을 적용하여 각각 설계신뢰도와 정기검사주기가 미치는 정량적인 효과에 대하여 분석을 수행하였다. 분석 결과를 통해, 현 제품의 설계신뢰도 범주 내에서는 설계신뢰도보다는 정기검사주기 관리가 저장신뢰도 향상에 더 중요한 요인이라는 것을 확인해 볼 수 있었다. In the case of a one-shot logistic equipment system that has been stored for a long time, reliability changes with the passage of time. Therefore, when the time comes to use, the storage reliability of the product is an important quality characteristic, and the existing studies have focused on the research for calculating the optimal period inspection cycle to improve the storage reliability. In this study, we analyzed the influence of the two factors on the storage reliability at the convergence point by analyzing the design reliability as well as the periodic inspection cycle. To do this, we applied the existing Martinez storage reliability model to the missile, a representative product of a one-shot system, and analyzed the quantitative effects of the design reliability and the periodic inspection cycle. From the results of the analysis, it was confirmed that the maintenance of the periodic inspection cycle is more important for the improvement of the storage reliability than the design reliability in the design reliability category of the current product.

Simplified stochastic temperature model for storage reliability estimation of solid rocket propellants

이동녁,조진연 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.1

In this study, a simplified stochastic temperature model is proposed for estimating the storage reliability of solid rocket propellants by temperature-induced damage. The cumulative damage to solid rocket propellants depends on the storage temperature history, and the storage reliability is related to the temperature variation and uncertainty. Therefore, a stochastic approach is required for the temperature model to estimate storage reliability. Several studies for the temperature specifications of weapons systems and materiel have focused on determining the limits of the operational environment. This paper presents a simple annual temperature model for storage reliability estimation by simulating domestic temperature statistics using temperature data provided by the Korea Meteorological Administration and Monte Carlo simulation. The simplified stochastic temperature model consists of six temperature distributions and three normalized diurnal temperature profiles. The simplified stochastic temperature model divides a year into three temperature categories grouped by month. Each temperature category has two temperature distributions, diurnal minimum and maximum temperatures, and one normalized diurnal temperature profile. It was confirmed that the logarithmic cumulative damage index induced by temperature variation and uncertainty for one year in solid rocket propellants has a normal distribution, and the proposed simplified stochastic temperature model can adequately simulate the cumulative damage distribution of the solid rocket propellants.

Erasure Codes-based Storage-aware Protocol for Preserving Cloud Data under Correlation Failures

Zhiqiang Ruan,Zhi Li 보안공학연구지원센터 2015 International Journal of Grid and Distributed Comp Vol.8 No.2

Distributed storage of cloud data imposes a great challenge for assuring data availability and reliability in the face of stochastic failures and attacks. Although redundancy scheme such as erasure codes or network coding schemes can be used to improve storage efficiency, they do not consider the scenario that the network may be split up into several regions due to correlated failures of storage components, which may not successfully reconstruct the original data. Furthermore, the stored data on the failed node need to be recovered to keep the same redundancy of network data while introducing low overhead. In view of this, we first devise an efficient algorithm that guarantees residual network has enough data segments to recreate the original data under correlated failures. Second, an efficient data recovery scheme is presented to repair the data stored on the failed nodes in case of Byzantine failures or pollution attacks. The proposed protocol benefits from several key features such as less storage cost, competitive communication cost, and much better data robustness comparing to the state of the art distributed storage systems.

장기 저장되는 일회성 시스템의 수명 관리 프로그램에 대한 연구

박동인,심행근 한국산학기술학회 2020 한국산학기술학회논문지 Vol.21 No.1

This paper presents an analysis of the shelf-life management program of the long-term storage one-shot system. The one-shot system is mainly maintained with long-term storage or non-operating status and is operated once at execution of the mission. The function corresponding to one-shot is mainly operated through a shelf-life item such as an explosive. The performance and characteristics of shelf-life item are subject to change as the storage period passes. Therefore, shelf-life management for maintaining good condition is very important during long-term storage, and criteria for management is necessary. We present a method for optimizing shelf-life extension by comparing criteria for management with current reliability. Next, the shelf-life evaluation schedule was decided by utilizing the reliability function of exponential distribution and Weibull distribution. Continuously accumulated test data from the shelf-life evaluation were analyzed, and the parameter of distribution was updated. The extension or expiration of shelf-life was selected by monitoring changes in reliability. In addition, we confirmed the applicability of the presented shelf-life management program by applying ASRP test data of the one-shot system K000 fuse. 본 논문에서는 일회성 시스템이 장기 저장되는 동안 수명을 관리하기 위한 프로그램에 대해 연구하였다. 일회성 시스템은 주로 장기간 저장 또는 비운용 상태로 유지되다 임무수행시 일회성으로 운용되는 특징이 있으며, 일회성에 해당하는 기능은 주로 화약과 같은 시효성 품목을 통해 발휘된다. 이러한 시효성 품목은 저장 기간이 경과됨에 따라 성능과 특성이 변화하는 품목으로서 장기 저장간 정상 상태를 유지하기 위한 수명 관리가 매우 중요하며, 체계적인 수명 관리를 위해서는 관리 기준 설정이 필요하다. 수명 관리 기준과 현재 신뢰도를 비교하여 수명연장을 결정하며, 차기 수명평가 시기를 결정하는 방법을 지수분포와 와이블분포별로 제시한다. 수명평가 결과 시험데이터를 지속적으로 누적하며 수명분포의 모수를 최신화하고 신뢰도 변화를 확인하여, 수명을 연장하거나 만료를 판정한다. 또한, 일회성 시스템인 K000 신관의 ASRP 시험데이터를 활용하여 제안된 수명 관리 프로그램에 따라 수명 관리가 어떻게 이뤄지게 되는지 적용 가능성을 확인하였다.

전자의무기록의 보관과 신뢰할 수 있는 제3의 기관의 활용

이호용(Lee, Ho-Yong) 한양법학회 2013 漢陽法學 Vol.24 No.4

The introduction of electronic medical records in Korea began in late 1990 and due to Medical Law revision in 2002 electronic documents instead of paper medical records made it possible to create and keep. Current level of use of electronic stays on the level of use of computerized medical information within a single medical institution, but soon-to-peer by establishing networks will lead to a step of transport and communalization of medical records. However, despite of the benefits of digitization of medical records, because of lingering information leakage and hacking, the possibility of modulation, measures to ensure the safety and reliability are still being discussed. The creation and storage of the electronic medical records is an important issue as important in the writing and storage of medical records. In the creation of electronic medical records as a way to prevent tampering with the electronic signature is to be presented, By doing this, is recognized as a valid electronic medical records. In storage of electronic medical records as to the important task of ensuring the safety and reliability, in order to solve this point, I propose the Trusted Third Party(TTP) to charge for storage. I reviewed if paper records are converted into electronic documents to be stored, whether conventional paper documents can be discarded or should be retained. In addition, I reviewed with respect to another point contained in storage of electronic medical records, that is the use of personal medical information. Because personal medical information by being utilized in medical research as data, may contribute significantly to patients of similar diseases or future generations for disease control and prevention. In particular, I review anonymized medical information could be taken advantage of the public interest such as medical research, and the applicability of “informed consent” theory to this. This paper consists of three parts. First, by verifying the significance and usefulness of electronic medical records, the possibility of activation of electronic medical records was examined. Second, by examining the problems of safety and reliability of electronic medical records that could be vulnerable, whether it is proper to charge the storage of electronic medical records to Trusted Third Party(TTP) were investigated. Third, if the storage of electronic medical records is charged to Certified e-Document Centre that is authorized Trusted Third Party(TTP), that there is not any confilicts in current laws was investigated.

에러 분포의 비대칭성을 활용한 대용량 3D NAND 플래시 메모리의 신뢰성 최적화 기법

김명석 대한임베디드공학회 2023 대한임베디드공학회논문지 Vol.18 No.1

Recent advances in flash technologies, such as 3D processing and multileveling schemes, have successfully increased the flash capacity. Unfortunately, these technology advances significantly degrade flash’s reliability due to a smaller cell geometry and a finer-grained cell state control. In this paper, we propose an asymmetric BER-aware reliability optimization technique (aBARO), new flash optimization that improves the flash reliability. To this end, we first reveal that bit errors of 3D NAND flash memory are highly skewed among flash cell states. The proposed aBARO exploits the unique per-state error model in flash cell states by selecting the most error-prone flash states and by forming narrow threshold voltage distributions (for the selected states only). Furthermore, aBARO is applied only when the program time (tPROG) gets shorter when a flash cell becomes aging, thereby keeping the program latency of storage systems unchanged. Our experimental results with real 3D MLC and TLC flash devices show that aBARO can effectively improve flash reliability by mitigating a significant number of bit errors. In addition, aBARO can also reduce the read latency by 40%, on average, by suppressing the read retries.