• Title/Summary/Keyword: expected time to failure

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A Study on the Estimation of the Optimum Lifetime of Elevator Components for Elevator Accident Prevention (엘리베이터 사고예방을 위한 승강기 부품의 최적 수명 추정에 관한 연구)

  • Kim, Han-jin;Hwang, Min-soo;Choi, Og-man;Lee, An-ki;Kim, Jae-chul
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.66 no.8
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    • pp.1278-1284
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    • 2017
  • As of December 2016, there are 608,828 elevators in operation in Korea and 179,790 elevators in more than 15 years. 30.4% of all elevator are aging. Improved maintenance of the elevator and proactive replacement of the parts of the elevator can extend the lifetime of the elevator and ensure safety. An unclean environment reduces the lifetime of elevator parts. If you do not clean the environment and prevent preventive parts replacement, eventually shortening the lifetime of the parts connected to the failed part or causing more damage will result in greater economic loss. Also, the risk of elevator safety accidents due to failures of elevator parts will be increased accordingly. The study of optimum replacement time of elevator parts will contribute to prevention of safety accident of elevator and prolongation of lifetime of elevator through preventive replacement of elevator parts.

Fault Pattern Analysis and Restoration Prediction Model Construction of Pole Transformer Using Data Mining Technique (데이터마이닝 기법을 이용한 주상변압기 고장유형 분석 및 복구 예측모델 구축에 관한 연구)

  • Hwang, Woo-Hyun;Kim, Ja-Hee;Jang, Wan-Sung;Hong, Jung-Sik;Han, Deuk-Su
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.9
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    • pp.1507-1515
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    • 2008
  • It is essential for electric power companies to have a quick restoration system of the faulted pole transformers which occupy most of transformers to supply stable electricity. However, it takes too much time to restore it when a transformer is out of order suddenly because we now count on operator in investigating causes of failure and making decision of recovery methods. This paper presents the concept of 'Fault pattern analysis and Restoration prediction model using Data mining techniques’, which is based on accumulated fault record of pole transformers in the past. For this, it also suggests external and internal causes of fault which influence the fault pattern of pole transformers. It is expected that we can reduce not only defects in manufacturing procedure by upgrading quality but also the time of predicting fault patterns and recovering when faults occur by using the result.

Implementation of Facility Management System for Plant Factory (식물공장 시설관리 시스템의 구현)

  • Lee, Yong-Woong;Seo, Beom-Seok;Kim, Chan-Woo;Kim, Kyung-Hee;Park, Yang-Ho;Shin, Chang-Sun
    • Journal of the Korea Society of Computer and Information
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    • v.16 no.2
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    • pp.141-151
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    • 2011
  • This paper suggests the Facility Management System for plant factory promising to be a core technology of the agriculture in the future. This system makes diagnoses that status from sensors or facilities in the factory for exact operation and monitors the internal environment with the control status in real-time. It is expected that we could operate a plant factory safely and effectively by using the system. The system consists of the data management module, the context provider module, the context interpreter module, the service provider module, the data storage and user interface. The system provide with the failure diagnosis service, the facility control service, and the high-reliability monitoring service via the interactions between above modules. The failure diagnosis service determines whether the sensors or facility devices are in failure or not, and informs the administrator of their conditions. The facility control service is activated in case if the facilities need to be managed during the diagnosis for failure or malfunction processes. The high-reliability monitoring service provides the administrator with verified data through the failure diagnosis service. Then we confirmed that the suggested system operates correctly through the system simulation.

A Study on Comparative Evaluation of Application of Software Reliability Model Dependent on Various Hazard Functions (다양한 위험함수에 의존한 소프트웨어 신뢰모형의 적용에 대한 비교 평가에 관한 연구)

  • Yang, Tae-Jin
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.11 no.6
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    • pp.800-806
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    • 2018
  • Software efficiency is the probability of failure free use in operating environments, and is the most fundamental factor affecting software system stability. The malfunction of the computer system used in the information technology field may cause a significant loss in the related industry. Therefore, in this study, we analyze the attributes of software reliability models that depend on various hazard functions based on finite fault NHPP model with software failure time data. The hazard function pattern of proposed model is constant for the Goel-Okumoto model, and the Minimax and Rayleigh models follow the incremental pattern, but the hazard function increase value of the Minimax model is smaller than that of the Rayleigh model and the Goel-Okumoto model. Also, the Minimax model was relatively efficient because the true value error of the mean value function m(t) and the mean square error (MSE) of the Minimax model were smaller than those of the Rayleigh and Goel-Okumoto models. The results of this study are expected to be useful for software developers as basic information about the hazard function.

Two-Dimensional Flood Inundation Analysis Resulting from Irrigation Reservoir Failure - Focused on the Real Case with the Minimal Data Set - (농업용 저수지 붕괴에 따른 2차원 홍수범람해석 -계측자료가 부족한 실제사례를 중심으로-)

  • Lee, Jae Young;Kim, Byunghyun;Park, Jun Hyung;Han, Kun Yeun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.36 no.2
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    • pp.231-243
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    • 2016
  • This study presents the applicability of two-dimensional (2D) flood inundation model by applying to real irrigation reservoir failure with limited available data. The study area is Sandae Reservoir placed in Gyeongju and downstream area of it and the reservoir was failured by piping in 2013. The breach hydrograph was estimated from one-dimensional (1D) hydrodynamic model and the discharge was employed for upstream boundary of 2D flood inundation model. Topography of study area was generated by integrating digital contour map and satellite data, and Cartesian grids with 3m resolution to consider geometry of building, road and public stadium were used for 2D flood inundation analysis. The model validation was carried out by comparing predictions with field survey data including reservoir breach outflow, flood extent, flood height and arrival time, and identifying rational ranges with allowed error. In addition, the applicability of 2D model is examined using different simulation conditions involving grid size, building and roughness coefficient. This study is expected to contributed to analysis of irrigation reservoirs were at risk of a failure and setting up Emergency Action Plan (EAP) against irrigation reservoir failure.

Adaptive Beamwidth Control Technique for Low-orbit Satellites for QoS Performance improvement based on Next Generation Military Mobile Satellite Networks (차세대 군 모바일 위성 네트워크 QoS 성능 향상을 위한 저궤도 위성 빔폭 적응적 제어 기법)

  • Jang, Dae-Hee;Hwang, Yoon-Ha;Chung, Jong-Moon
    • Journal of Internet Computing and Services
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    • v.21 no.6
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    • pp.1-12
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    • 2020
  • Low-Orbit satellite mobile networks can provide services through miniaturized terminals with low transmission power, which can be used as reliable means of communication in the national public disaster network and defense sector. However, the high traffic environment in the emergency preparedness situation increases the new call blocking probability and the handover failure probability of the satellite network, and the increase of the handover failure probability affects the QoS because low orbit satellites move in orbit at a very high speed. Among the channel allocation methods of satellite communication, the FCA shows relatively better performance in a high traffic environment than DCA and is suitable for emergency preparedness situations, but in order to optimize QoS when traffic increases, the new call blocking and the handover failure must be minimized. In this paper, we propose LEO-DBC (LEO satellite dynamic beam width control) technique, which improves QoS by adaptive adjustment of beam width of low-orbit satellites and call time of terminals by improving FCA-QH method. Through the LEO-DBC technique, it is expected that the QoS of the mobile satellite communication network can be optimally maintained in high traffic environments in emergency preparedness situations.

Comparative Evaluation on the Cost Analysis of Software Development Model Based on Weibull Lifetime Distribution (와이블 수명분포에 근거한 소프트웨어 개발모형의 비용 분석에 관한 비교 평가)

  • Bae, Hyo-Jeong
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.22 no.3
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    • pp.193-200
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    • 2022
  • In this study, the finite-failure NHPP software reliability model was applied to the software development model based on the Weibull lifetime distribution (Goel-Okumoto, Rayleigh, Type-2 Gumbe), which is widely used in the software reliability field, and then the cost attributes were compared and evaluated. For this study, failure time data detected during normal operation of the software system were collected and used, the most-likelihood estimation (MLE) method was applied to the parameter estimation of the proposed model, and the calculation of the nonlinear equation was solved using the binary method. As a result, first, in the software development model, when the cost of testing per unit time and the cost of removing a single defect increased, the cost increased but the release time did not change, and when the cost of repairing failures detected during normal system operation increased, the cost increased and the release time was also delayed. Second, as a result of comprehensive comparative analysis of the proposed models, it was found that the Type-2 Gumble model was the most efficient model because the development cost was lower and the release time point was relatively faster than the Rayleigh model and the Goel-Okumoto basic model. Third, through this study, the development cost properties of the Weibull distribution model were newly evaluated, and the analyzed data is expected to be utilized as design data that enables software developers to explore the attributes of development cost and release time.

Experimental investigation of local damage in high strength concrete columns using a shaking table

  • Bairrao, Rogerio;Kacianauskas, Rimantas;Kliukas, Romualdas
    • Structural Engineering and Mechanics
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    • v.19 no.5
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    • pp.581-602
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    • 2005
  • In this paper the accumulation of local damage during the cyclic loading in reinforced high-strength concrete columns is experimentally investigated. Two identical column specimens with annular cross-section and spiral reinforcement were designed and two tests, up to failure, under the action of a constant vertical concentrated force and a time-dependent concentrated horizontal force, were carried out at the LNEC shaking tables facility. Sine type signals, controlled in amplitude, frequency and time duration were used for these experiments. The concept of local damage based on local stiffness degradation is considered in detail and illustrated by experimental results. The specimens were designed and reinforced in such a way that the accumulation of damage was predicted by dominating deformations (cracking and crushing of the concrete) while the increasing of the loading values was a dominating factor of damage. It was observed that the local damage of HSC columns has exposed their anisotropic local behaviour. The damage accumulation was slightly different from the expected in accordance with the continuum damage concept, and a partial random character was observed.

Development of a complex failure prediction system using Hierarchical Attention Network (Hierarchical Attention Network를 이용한 복합 장애 발생 예측 시스템 개발)

  • Park, Youngchan;An, Sangjun;Kim, Mintae;Kim, Wooju
    • Journal of Intelligence and Information Systems
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    • v.26 no.4
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    • pp.127-148
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    • 2020
  • The data center is a physical environment facility for accommodating computer systems and related components, and is an essential foundation technology for next-generation core industries such as big data, smart factories, wearables, and smart homes. In particular, with the growth of cloud computing, the proportional expansion of the data center infrastructure is inevitable. Monitoring the health of these data center facilities is a way to maintain and manage the system and prevent failure. If a failure occurs in some elements of the facility, it may affect not only the relevant equipment but also other connected equipment, and may cause enormous damage. In particular, IT facilities are irregular due to interdependence and it is difficult to know the cause. In the previous study predicting failure in data center, failure was predicted by looking at a single server as a single state without assuming that the devices were mixed. Therefore, in this study, data center failures were classified into failures occurring inside the server (Outage A) and failures occurring outside the server (Outage B), and focused on analyzing complex failures occurring within the server. Server external failures include power, cooling, user errors, etc. Since such failures can be prevented in the early stages of data center facility construction, various solutions are being developed. On the other hand, the cause of the failure occurring in the server is difficult to determine, and adequate prevention has not yet been achieved. In particular, this is the reason why server failures do not occur singularly, cause other server failures, or receive something that causes failures from other servers. In other words, while the existing studies assumed that it was a single server that did not affect the servers and analyzed the failure, in this study, the failure occurred on the assumption that it had an effect between servers. In order to define the complex failure situation in the data center, failure history data for each equipment existing in the data center was used. There are four major failures considered in this study: Network Node Down, Server Down, Windows Activation Services Down, and Database Management System Service Down. The failures that occur for each device are sorted in chronological order, and when a failure occurs in a specific equipment, if a failure occurs in a specific equipment within 5 minutes from the time of occurrence, it is defined that the failure occurs simultaneously. After configuring the sequence for the devices that have failed at the same time, 5 devices that frequently occur simultaneously within the configured sequence were selected, and the case where the selected devices failed at the same time was confirmed through visualization. Since the server resource information collected for failure analysis is in units of time series and has flow, we used Long Short-term Memory (LSTM), a deep learning algorithm that can predict the next state through the previous state. In addition, unlike a single server, the Hierarchical Attention Network deep learning model structure was used in consideration of the fact that the level of multiple failures for each server is different. This algorithm is a method of increasing the prediction accuracy by giving weight to the server as the impact on the failure increases. The study began with defining the type of failure and selecting the analysis target. In the first experiment, the same collected data was assumed as a single server state and a multiple server state, and compared and analyzed. The second experiment improved the prediction accuracy in the case of a complex server by optimizing each server threshold. In the first experiment, which assumed each of a single server and multiple servers, in the case of a single server, it was predicted that three of the five servers did not have a failure even though the actual failure occurred. However, assuming multiple servers, all five servers were predicted to have failed. As a result of the experiment, the hypothesis that there is an effect between servers is proven. As a result of this study, it was confirmed that the prediction performance was superior when the multiple servers were assumed than when the single server was assumed. In particular, applying the Hierarchical Attention Network algorithm, assuming that the effects of each server will be different, played a role in improving the analysis effect. In addition, by applying a different threshold for each server, the prediction accuracy could be improved. This study showed that failures that are difficult to determine the cause can be predicted through historical data, and a model that can predict failures occurring in servers in data centers is presented. It is expected that the occurrence of disability can be prevented in advance using the results of this study.

Seismic torsional vibration in elevated tanks

  • Dutta, Sekhar Chandra;Murty, C.V.R.;Jain, Sudhir K.
    • Structural Engineering and Mechanics
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    • v.9 no.6
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    • pp.615-636
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    • 2000
  • Some elevated water tanks have failed due to torsional vibrations in past earthquakes. The overall axisymmetric structural geometry and mass distribution of such structures may leave only a small accidental eccentricity between centre of stiffness and centre of mass. Such a small accidental eccentricity is not expected to cause a torsional failure. This paper studies the possibility of amplified torsional behaviour of elevated water tanks due to such small accidental eccentricity in the elastic as well as inelastic range; using two simple idealized systems with two coupled lateral-torsional degrees of freedom. The systems are capable of retaining the characteristics of two extreme categories of water tanks namely, a) tanks on staging with less number of columns and panels and b) tanks on staging with large number of columns and panels. The study shows that the presence of a small eccentricity may lead to large displacement of the staging edge in the elastic range, if the torsional-to-lateral time period ratio $({\tau})$ of the elevated tanks lies within a critical range of 0.7< ${\tau}$ <1.25. Inelastic behaviour study reveals that such excessive displacement in some of the reinforced concrete staging elements may cause unsymmetric yielding. This may lead to progressive strength deterioration through successive yielding in same elements under cyclic loading during earthquakes. Such localized strength drop progressively develop large strength eccentricity resulting in large localized inelastic displacement and ductility demand, leading to failure. So, elevated water tanks should have ${\tau}$ outside the said critical range to avoid amplified torsional response. The tanks supported on staging with less number of columns and panels are found to have greater torsional vulnerability. Tanks located near faults seem to have torsional vulnerability for large ${\tau}$.