• Title/Summary/Keyword: system lifetime

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Multistress Life Models of Epoxy Encapsulated Magnet wire under High Frequency Pulsating Voltage

  • Grzybowski, S.;Feilat, E.A.;Knight, P.
    • KIEE International Transactions on Electrophysics and Applications
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    • v.3C no.1
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    • pp.1-4
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    • 2003
  • This paper presents an attempt to develop probabilistic multistress life models to evaluate the lifetime characteristics of epoxy-encapsulated magnet wire with heavy build polyurethane enamel. A set of accelerated life tests were conducted over a wide range of pulsating voltages, temperatures, and frequencies. Samples of fine gauge twisted pairs of the encapsulated magnet wire were tested us-ing a pulse endurance dielectric test system. An electrical-thermal lifetime function was combined with the Weibull distribution of lifetimes. The parameters of the combined Weibull-electrical-thermal model were estimated using maximum likelihood estimation. Likewise, a generalized electrical-thermal-frequency life model was also developed. The parameters of this new model were estimated using multiple linear regression technique. It was found in this paper that lifetime estimates of the two proposed probabilistic multistress life models are good enough. This suggests the suitability of using the general electrical-thermal-frequency model to estimate the lifetime of the encapsulated magnet wire over a wide range of voltages, temperatures and pulsating frequencies.

Estimation of lifetime dental expenditures for periodontitis (치주질환 유병자의 생애 치과의료비 추정)

  • Kim, Yun-Jeong;Kwang, Jung-Sook
    • Journal of Korean society of Dental Hygiene
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    • v.21 no.3
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    • pp.245-253
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    • 2021
  • Objectives: The objective of this paper was to estimate a South Korean's lifetime dental expenditures for periodontitis. Methods: For our study, we collected data from the Korea Health Panel Survey (KHPS), from 2010 to 2016. The outpatient dental care data of 1,919,608 samples of periodontitis were extracted using R version 3.0 and estimations of lifetime dental expenditures for them were generated using Excel. Results: Over 50% of the lifetime dental expenditure of South Koreans was spent for periodontitis, and incurred after the age of 40. The results showed that an estimate of average per capita lifetime dental expenditure for men (approximately 13 million won) was greater than that for women (approximately 8.8 million won) for periodontitis. Conclusions: Efficient methods for the prevention and management of periodontitis are necessary, and a new paradigm of health care system is required to reduce dental expenditure through its prevention.

Probabilistic-based prediction of lifetime performance of RC bridges subject to maintenance interventions

  • Tian, Hao;Li, Fangyuan
    • Computers and Concrete
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    • v.17 no.4
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    • pp.499-521
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    • 2016
  • In this paper, a probabilistic- and finite element-based approach to evaluate and predict the lifetime performance of reinforced concrete (RC) bridges undergoing various maintenance actions is proposed with the time-variant system reliability being utilized as a performance indicator. Depending on their structural state during the degradation process, the classical maintenance actions for RC bridges are firstly categorized into four types: Preventive type I, Preventive type II, Strengthening and Replacement. Preventive type I is used to delay the onset of steel corrosion, Preventive type II can suppress the corrosion process of reinforcing steel, Strengthening is the application of various maintenance materials to improve the structural performance and Replacement is performed to restore the individual components or overall structure to their original conditions. The quantitative influence of these maintenance types on structural performance is investigated and the respective analysis modules are written and inputted into the computer program. Accordingly, the time-variant system reliability can be calculated by the use of Monte Carlo simulations and the updated the program. Finally, an existing RC continuous bridge located in Shanghai, China, is used as an illustrative example and the lifetime structural performance with and without each of the maintenance types are discussed. It is felt that the proposed approach can be applied to various RC bridges with different structural configurations, construction methods and environmental conditions.

The Study on the Lifetime Estimation using Fault Tree Analysis in Design Process of LNG Compressor (천연가스 압축기 설계 단계에서 FTA를 이용한 수명 예측 연구)

  • Han, Yongshik;Do, Kyu Hyung;Kim, Taehoon;Kim, Myungbae;Choi, Byungil
    • Transactions of the Korean hydrogen and new energy society
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    • v.26 no.2
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    • pp.192-198
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    • 2015
  • Fault Tree Analysis to predict the lifetime in the design process of LNG compressor is considered. Fault Trees for P & ID of the compressor are created. Individual components that comprise the compressor are configured with the basic event. The failure rates in the PDS and OREDA are applied. As results, the system failure rate and the reliability over time are obtained. Further, the power transmission and the shaft seal system is confirmed to confidentially importantly contribute to the overall lifetime of the system. These techniques will help to improve the reliability of design of large scale machinery such as a plant.

Lifetime prediction of optocouplers in digital input and output modules based on bayesian tracking approaches

  • Shin, Insun;Kwon, Daeil
    • Smart Structures and Systems
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    • v.22 no.2
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    • pp.167-174
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    • 2018
  • Digital input and output modules are widely used to connect digital sensors and actuators to automation systems. Digital I/O modules provide flexible connectivity extension to numerous sensors and actuators and protect systems from high voltages and currents by isolation. Components in digital I/O modules are inevitably affected by operating and environmental conditions, such as high voltage, high current, high temperature, and temperature cycling. Because digital I/O modules transfer signals or isolate the systems from unexpected voltage and current transients, their failures may result in signal transmission failures and damages to sensitive circuitry leading to system malfunction and system shutdown. In this study, the lifetime of optocouplers, one of the critical components in digital I/O modules, was predicted using Bayesian tracking approaches. Accelerated degradation tests were conducted for collecting the critical performance parameter of optocouplers, current transfer ratio (CTR), during their lifetime. Bayesian tracking approaches, including extended Kalman filter and particle filter, were applied to predict the failure. The performance of each prognostic algorithm was then compared using accuracy and robustness-based performance metrics.

The investigation of a new fast timing system based on DRS4 waveform sampling system

  • Zhang, Xiuling;Du, Chengming;Chen, Jinda;Yang, Herun;kong, Jie;Yang, Haibo;Ma, Peng;Shi, Guozhu;Duan, limin;Hu, Zhengguo
    • Nuclear Engineering and Technology
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    • v.51 no.2
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    • pp.432-438
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    • 2019
  • In the study of nuclear structure, the fast timing technique can be used to measure the lifetime of excited states. In the paper, we have developed a new fast timing system, which is made up of two $LaBr_3:Ce$ detectors and a set of waveform sampling system. The sampling system based on domino ring sampler version 4 chip (DRS4) can digitize and store the waveform information of detector signal, with a smaller volume and higher timing accuracy, and the waveform data are performed by means of digital waveform analysis methods. The coincidence time resolution of the fast timing system for two annihilation 511 keV ${\gamma}$ photon is 200ps (FWHM), the energy resolution is 3.5%@511 keV, and the energy linear response in the large dynamic range is perfect. Meanwhile, to verify the fast timing performance of the system, the $^{152}Gd-2_1^+$ state form ${\beta}^+$ decay of $^{152}Eu$ source is measured. The measured lifetime is $45.3({\pm}5.0)ps$, very close to the value of the National Nuclear Data Center (NNDC: $46.2({\pm}3.9)ps$). The experimental results indicate that the fast timing system is capable of measuring the lifetime of dozens of ps. Therefore, the system can be widely used in the research of the fast timing technology.

고온고압배관의 손상평가 및 실제 사례

  • Ha, Jeong-Su
    • 열병합발전
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    • s.27
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    • pp.5-9
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    • 2002
  • High pressure steam pipe in power plants is subjected to service conditions under which creep processes take place limiting the component's lifetime. To ensure a safe and economic operation it is necessary to get accurate information about the lifetime situation of single components as well as of the whole system. Careful evaluation is combined with FEM analysis, NDT, microstructure evaluation. Especially, 14MoV63 steel is used as material for main steam pipe for 30 years old power plants. In service inspections have shown an increasing number of cracks and creep cavities beside stress concentration parts. A detailed analysis came to the conclusion that lifetime has been consumed to a high degree, 80%level.

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Dynamic Key Lifetime Change Protocol for Performance Improvement of Virtual Private Networks using IPSec (IPSec을 적용한 가상사설망의 성능개선을 위한 동적 키 재생성 주기 변경 프로토콜)

  • 한종훈;이정우;박성한
    • Proceedings of the IEEK Conference
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    • 2003.11c
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    • pp.125-128
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    • 2003
  • In this paper, we propose a dynamic key lifetime change protocol for performance enhancement of virtual private networks using IPSec. The proposed protocol changes the key lifetime according to the number of secure tunnels. The proposed protocol is implemented with Linux 2.4.18 and FreeS/WAN 1.99. The system employing our proposed protocol performs better than the original version in terms of network performance and security.

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A Study On Realization of SLV System for Selecting Supplier (효율적인 공급자 선정을 위한 SLV(Supplier Lifetime Value)시스템 구현에 관한 사례 연구)

  • 양광모;박재현;강경식
    • Journal of the Korea Safety Management & Science
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    • v.6 no.2
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    • pp.167-178
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    • 2004
  • Supply chain management and e-procurement system built in the company, are set goal of internal process improvement. This paper show how SLV(Supplier Lifetime Value) can be used to structure the supplier in automotive part manufacturer, the method of selection is described and a detailed example of how SLV can be used and allocation of order Quantity for the selected suppliers also are provided, and aims at giving a method to realization profitable supplier relation using search for SL V system development which is making corporation with supplier, in the favor of decision supplier.

Life Estimation of DC Link Electroytic Capacitors (직류 링크 전해 커패시터의 수명 추정)

  • 이동춘
    • Proceedings of the KIPE Conference
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    • 2000.07a
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    • pp.57-60
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    • 2000
  • An aluminum electrolytic capacitor is used in DC Link of ac motor drive system. In this case it usually has the shortest lifetime in the system and then determines the system lifetime. Therefore life estimation of the electrolytic capacitor is needed for maintenance of th circuit. In this paper a method for life estimation is presented with a ESR(equivalent series resistance) model and a heat transfer model of capacitor that can be used to estimate operating temperature it is investigated through a simple example using ESR and heat transfer.

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