• Title, Summary, Keyword: Failure line

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The Novel Concepts for Reliability Technology

  • Ryu, DongSu
    • Corrosion Science and Technology
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    • v.4 no.5
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    • pp.201-206
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    • 2005
  • Starting with the meaning of the word quality, diverse concepts connoted by the term are examined. Instead of a bathtub curve, the desirable shape of a failure rate covering the entire life of a good product, which might be called hockey-stick line, is introduced. From the hockey-stick line and the definition of reliability, two measurements are extracted. The terms r-reliability (failure rate) and durability (product life) are explained. The conceptual analysis of failure mechanics explains that reliability technology pertains to design area. The desirable shape of hazard rate curve of electronic items, hockey-stick line, clarifies that Mean-Time-to-failure (MTTF) as the inverse of failure rate can be regarded a nominal life. And Bx life, different from MTTF, is explained. Reliability relationships between components and set products are explained. Reshaped definitions of r-reliability and durability are recommended. The procedure to improve reliability and the reasons for failing to identify failure mode are clarified in order to search right solutions. And generalized Life-Stress failure model is recommended for the calculation of acceleration factor.

A Case Study on Failure and Analysis of Air Over Hydraulic Brake Line (공기 유압식 브레이크 라인 파손 사례 및 파손 분석 연구)

  • Park, Jeongman;Park, Jongjin
    • Journal of Auto-vehicle Safety Association
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    • v.12 no.2
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    • pp.47-55
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    • 2020
  • In this case study, the brake line failure of air over hydraulic(AOH) brake system is described. AOH brake system is applied to commercial vehicles between 5 to 8 tons. It consists of a hydraulic system using compressed air and operates the air master to form hydraulic pressure to transfer braking power to the wheels. When the brake lines of the system applied to vehicles with high load capacity are damaged, the braking force of one shaft is lost, and the braking distance increases rapidly, leading to a big accident. Failure of the brake line occurs due to various causes such as road surface fragmentation, corrosion of the line, and aged deterioration of air brake hose. The braking force could be decreased even when a very small break in the form of a pin-hole occurs. However, it is difficult to find a part where the thickness of the line is thin due to stone pecking or corrosion generated in the pin-hole formed on the brake line located under the lower part of the vehicle by the sensory evaluation or the conventional braking force test. Accordingly, it is necessary to analyze the condition and cause of the failure of the brake line more precisely when the accident investigation of the heavy vehicles, and also to examine the necessity of the advanced test for the aged brake line.

Experimental and numerical study on the collapse failure of long-span transmission tower-line systems subjected to extremely severe earthquakes

  • Tian, Li;Fu, Zhaoyang;Pan, Haiyang;Ma, Ruisheng;Liu, Yuping
    • Earthquakes and Structures
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    • v.16 no.5
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    • pp.513-522
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    • 2019
  • A long-span transmission tower-line system is indispensable for long-distance electricity transmission across a large river or valley; hence, the failure of this system, especially the collapse of the supporting towers, has serious impacts on power grids. To ensure the safety and reliability of transmission systems, this study experimentally and numerically investigates the collapse failure of a 220 kV long-span transmission tower-line system subjected to severe earthquakes. A 1:20 scale model of a transmission tower-line system is constructed in this research, and shaking table tests are carried out. Furthermore, numerical studies are conducted in ABAQUS by using the Tian-Ma-Qu material model, the results of which are compared with the experimental findings. Good agreement is found between the experimental and numerical results, showing that the numerical simulation based on the Tian-Ma-Qu material model is able to predict the weak points and collapse process of the long-span transmission tower-line system. The failure of diagonal members at weak points constitutes the collapse-inducing factor, and the ultimate capacity and weakest segment vary with different seismic wave excitations. This research can further enrich the database for the seismic performance of long-span transmission tower-line systems.

Reliability analysis of wind-excited structures using domain decomposition method and line sampling

  • Katafygiotis, L.S.;Wang, Jia
    • Structural Engineering and Mechanics
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    • v.32 no.1
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    • pp.37-53
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    • 2009
  • In this paper the problem of calculating the probability that the responses of a wind-excited structure exceed specified thresholds within a given time interval is considered. The failure domain of the problem can be expressed as a union of elementary failure domains whose boundaries are of quadratic form. The Domain Decomposition Method (DDM) is employed, after being appropriately extended, to solve this problem. The probability estimate of the overall failure domain is given by the sum of the probabilities of the elementary failure domains multiplied by a reduction factor accounting for the overlapping degree of the different elementary failure domains. The DDM is extended with the help of Line Sampling (LS), from its original presentation where the boundary of the elementary failure domains are of linear form, to the current case involving quadratic elementary failure domains. An example involving an along-wind excited steel building shows the accuracy and efficiency of the proposed methodology as compared with that obtained using standard Monte Carlo simulations (MCS).

A Risk Evaluation Model of Power Distribution Line Using Bayesian Rule -Overhead Distribution System- (베이즈 규칙을 활용한 배전선로 위험도 평가모델 -가공배전분야-)

  • Joung, Jong-Man;Park, Yong-Woo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.6
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    • pp.870-875
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    • 2013
  • After introducing diagnosis equipment power failure prevention activities for distribution system have become more active. To do facility diagnosis and maintenance work more efficiently we need to evaluate reliability for the system and should determine the priority line with appropriate criteria. Thus, to calculate risk factor for the power distribution line that are composed of many component facilities its historical failure events for the last 5 years are collected and analysed. The failure statics show that more than 60% of various failures are related to environment factors randomly and about 20% of the failures are refer to the aging. As a strategic evaluation system reflecting these environmental influence is needed, a system on the basis of the probabilistic approach related statical variables in terms of failure rate and failure probability of electrical components is proposed. The figures for the evaluation are derived from the field failure DB. With adopting Bayesian rule we can calculate easily about conditional probability query. The proposed evaluation system is demonstrated with model system and the calculated indices representing the properties of the model line are discussed.

A Study on the Failure Behavior of the Reinforced Earth Wall Structures according to the Deformed Types of the Face (전면부 변형형태에 따른 보강토 벽체 구조물의 파괴거동에 관한 연구)

  • 김준석;이상덕
    • Journal of the Korean Geotechnical Society
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    • v.15 no.4
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    • pp.167-173
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    • 1999
  • In this paper the failure behavior of the reinforced earth retaining wall structures according to the deformed types of the face was studied by model test using carbon rods. In model test the behavior of the face for the model of the reinforced earth wall was divided into three cases : the displacement of the top part(case 1), the lateral displacement(case 2) and the displacement of the lower part (case 3). The photographic method was applied to examine the failure line of the deformed wall with the naked eye. The failure line shows a parabolic shape for case 1, a large circular arc for case 2 and a logarithmic spiral for case 3 in the experimental results. The design failure line for the coherent gravity structure hypothesis was most similar to the failure line for the case of the lower part displacement.

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A Study on the Surge Analysis considering Surge Arrester and Grounding System in the Combined Distribution System (혼합 배전계통에서 피뢰기적용과 접지시스템 변경을 고려한 서지 해석에 관한 연구)

  • Yun, Chang-Sub;Lee, Jong-Beom;Kim, Beong-Suk
    • Proceedings of the KIEE Conference
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    • pp.204-205
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    • 2006
  • This paper describes the protective ability of lightning arrestor in combined distribution system with power cable. To evaluate the protective ability, change of arrestor and grounding location are considered. On the other hand, arrestor developed by Cooper Power Systems for underground power cable system, is considered to evaluate surge protective ability as in underground system, when arrestor occurs failure has overhead line. The result shows that lightning arrestor in combined distribution system with power cable protect effectively when failure at arrestor in overhead line. On the other hand, arrestor developed by Cooper Power Systems for underground power cable system, is considered to evaluate surge protective ability in underground distribution system, when arrestor of overhead line has failure. The result shows that lightning arrestor installed in underground cable can effectively protected cables from surge when arrestor of overhead line has failure. And also even though grounding locations are decreased, it is revealed that protective ability is nearly similar.

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On-line Failure Detection Method of DC Output Filter Capacitor in Power Converters (전력변환장치에서의 DC 출력 필터 커패시터의 온라인 고장 검출기법)

  • Shon, Jin-Geun
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.58 no.4
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    • pp.483-489
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    • 2009
  • Electrolytic capacitors are used in variety of equipments as smoothening element of the power converters because it has high capacitance for its size and low price. Electrolytic capacitors, which is most of the time affected by aging effect, plays a very important role for the power electronics system quality and reliability. Therefore it is important to estimate the parameter of an electrolytic capacitor to predict the failure. This objective of this paper is to propose a new method to detect the rise of equivalent series resistor(ESR) in order to realize the online failure prediction of electrolytic capacitor for DC output filter of power converter. The ESR of electrolytic capacitor estimated from RMS result of filtered waveform(BPF) of the ripple capacitor voltage/current. Therefore, the preposed online failure prediction method has the merits of easy ESR computation and circuit simplicity. Simulation and experimental results are shown to verify the performance of the proposed on-line method.

Failure Analysis of Porcelain Suspension Insulators for Distribution Line (배전용 자기제 현수애자의 고장 분석)

  • 김찬영;김추용;송일근;이병성;한용희
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.157-160
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    • 1999
  • The paper provides the results of failure analysis for the porcelain suspension insulators. The comparisons of characteristics were made as a function of failed and unfailed isulators which had been used in real distribution line. This paper also described the failure modes which could be occurred in the fields. The cracks inside cap were detected though measuring the resistance or the leakage current. The ratio of open porosity was calculated from the Archimedes Method. The failure analyses of porcelain suspension insulators were conducted from the various analysis method.

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Reliability Evaluation of ATC for High-Speed Line Center (고속 Line Center의 ATC 신뢰성 평가)

  • Lee Seung-Woo;Lee Hwa-Ki;Shin Dong-Hwan
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.6
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    • pp.111-118
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    • 2006
  • Recently, the reliability evaluation and analysis are applied far many industrial products which are required to guarantee in quality and efficiency. The purpose of this paper is to present some of reliability evaluation methodologies that are applicable to machine tools. Especially ATC (Automatic Tool Changer), which is a core component of line center, was chosen as the target of the reliability evaluation and analysis. The scope of research is reliability prediction, reliability test and evaluates their results. The results of reliability evaluation have shown the failure rates, MTBF (Mean Time Between Failure), reliability for those components of ATC and real tests reliability through the constructed reliability test-bed. It is expected that proposed methodologies would increase reliability for a high-speed line center.