• Title/Summary/Keyword: Multiple failure

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Influence of Physical and Psychological Symptoms on Exercise Adherence in Patients with Heart Failure: Focused on the Mediating Effects of Self-efficacy (심부전 환자의 신체적·심리적 증상이 운동이행에 미치는 영향: 운동 자기효능감의 매개효과를 중심으로)

  • Jin, Hyekyung;Kim, Jong Hyun;Kim, Minju
    • Journal of Korean Academy of Fundamentals of Nursing
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    • v.26 no.1
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    • pp.52-61
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    • 2019
  • Purpose: The aim of this study was to examine the mediating effect of self-efficacy in the relationship of physical and psychological symptoms to exercise adherence in patients with heart failure. Methods: The participants in this study were 186 patients with heart failure in two hospitals located in Busan. The measures included questions about general and disease characteristics, physical symptoms, psychological symptoms, self-efficacy for exercise, and exercise adherence. Data were analyzed using t-test, ANOVA, Pearson correlation coefficients, simple and multiple regression using Baron and Kenny steps for mediation. Results: There were significant differences in age, gender and comorbidity on exercise adherence. There were also significant correlations among physical and psychological symptoms, self-efficacy for exercise, and exercise adherence. Self-efficacy for exercise showed partial mediating effects in the relationship between physical symptoms and exercise adherence. Conclusion: Based on the findings of this study, the enhancement of self-efficacy for exercise may positively affect the exercise compliance of the patients with health failure, even while they are experiencing physical symptoms. Therefore, it is necessary to develop effective strategies to enhance self-efficacy for exercise.

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.

Fusion Tracking Filter for Satellite Launch Vehicles (위성발사체 궤도추정을 위한 융합필터 연구)

  • Ryu, Seong Sook;Kim, Jeongrae;Song, Yong Kyu;Ko, Jeonghwan
    • Journal of Aerospace System Engineering
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    • v.1 no.3
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    • pp.37-42
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    • 2007
  • The flight safety system for the satellite launch vehicles is required in order to minimize the risk due to launch vehicle failure. For prompt and reliable decision of flight termination, the flight safety system usually uses multiple sensors to estimate launch vehicle's flight trajectory. In that case, multiple types of observed tracking data makes it difficult to identify the flight termination condition. Therefore, a fusion tracking filter handling the multiple tracking data is necessary for the flight safety system. This research developed a simulation software for generating multiple types of launch vehicle tracking data, and then processed the data with fusion filters.

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The Suppression of Structural Vibration Using Cantilevers as Multiple Tuned Mass Damper (외팔보 형태의 수동형 Multiple Tuned Mass Damper를 이용한 구조물의 진동 억제)

  • 박재관;백윤수
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1996.04a
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    • pp.169-176
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    • 1996
  • In order to suppress the structural vibration more effectively, Multiple Tuned Mass Damper(MTMD) which is composed of a number of Tuned Mass Damper(TMD) can be used. Especially, the passive MTMD has several advantages over active TMD like easy installment and maintenance, cost and performance for power failure situation(severe damage of power lines from earthquake), etc.. For this purpose the mass and damping ratio of MTMD and the distributed frequency range which shows the range of MTMD's distribution are used as main design parameters. When the passive MTMD is constituted with multiple cantilevers, the facility in its real production and its need for only a smaller space can be named as its several advantages. In this study, the satisfactory results were obtained from the composition of MTMD utilizing dynamic characters of cantilevers, and the verification was done by the comparison of the analysis from MTMD with the computer simulation.

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T-stress solutions for cracks in rectangular plates with multiple holes

  • Yu, Jackie;Wang, Xin;Tan, Choon-Lai
    • Structural Engineering and Mechanics
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    • v.26 no.5
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    • pp.557-568
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    • 2007
  • The elastic T-stress is increasingly being recognized as an important second parameter to the stress intensity factor for fracture and fatigue assessments. In this paper, the mutual or M-contour integral approach is employed in conjunction with the Boundary Element Method (BEM) to determine the numerical T-stress solutions for cracks in plates with multiple holes. The problems investigated include plates of infinite width with multiple holes at which single or double, symmetric cracks have grown from. Comparisons of these results are also made with the corresponding solutions of finite plates with a single hole. For completeness, stress intensity factor solutions for the cracked geometries analyzed are presented as well. These results will be useful for failure assessments using the two-parameter linear elastic fracture mechanics approach.

An interconnection, modelling and simulation for a multi-robot systems(MRS) (다중 로봇 시스템의 결합, 모델링 및 시뮬레이션)

  • 이기동;홍지민;이범희;고명삼
    • 제어로봇시스템학회:학술대회논문집
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    • 1991.10a
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    • pp.1149-1154
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    • 1991
  • For a robotic workcell, which consists of multiple robots, several interconnection methods are presented in terms of the processor based architecture. Since few attempts have been made to formulate and analyze multiple robot system(MRS), we turn the knowledge of multiple processor system(MPS) or multiple computer system(MCS) to good account. The performance evaluation is achieved through queueing analysis, the aim being to compare their response time, utilization, probability of service failure under different workload. To verify the validity of the proposed analysis methods, a computer simulation is performed. The results together with comments presented here give some useful guidelines for the selection of an appropriate interconnection method.

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Fatigue Life Estimation of Welded Joints by using Mk-factor under a Propagation Mechanism of Multiple Collinear Surface Cracks (Mk-계수를 고려한 용접부 복수 표면균열 진전수명 평가)

  • 한승호;한정우;신병천;김재훈
    • Journal of Welding and Joining
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    • v.22 no.4
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    • pp.73-81
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    • 2004
  • Failure mechanisms of welded joints under fatigue loads are interpreted that multiple collinear surface cracks initiating randomly along the weld toes propagate under the mutual interaction and coalescence of adjacent two cracks. To estimate fatigue crack propagation life for three types of the representative welded joints, i.e. non-load carrying cruciform, cover plate and longitudinal stiffener joint, the stress intensity factors at the front of the surface cracks have to be calculated, which are influenced strongly by the geometry of attachments, weld toes and the crack shapes. For the effective calculation of the stress intensity factors the Mk-factor was introduced which can be derived by a parametric study performed by FEM considering influence of the geometrical effects. The fatigue life of the cruciform joint was estimated by using the Mk-factors and the method considering the propagation mechanisms of the multiple surface cracks. Analysis results for the fatigue life had a good agreement with that of experiment.

Reliability analysis of an embedded system with multiple vacations and standby

  • Sharma, Richa;Kaushik, Manju;Kumar, Gireesh
    • International Journal of Reliability and Applications
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    • v.16 no.1
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    • pp.35-53
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    • 2015
  • This investigation deals with reliability and sensitivity analysis of a repairable embedded system with standby wherein repairman takes multiple vacations. The hardware system consists of 'M' operating and 'S' standby components. The repairman can leave for multiple vacations of random length during its idle time. Whenever any operating unit fails, it is immediately replaced by a standby unit if available. Moreover, governing equations of an embedded system are constructed using appropriate birth-death rates. The vacation and repair time of repairman are exponentially distributed. The matrix method is used to find the steady-state probabilities of the number of failed components in the embedded system as well as other performance measures. Reliability indexes are presented. Further, numerical experiments are carried out for various system characteristics to examine the effects of different parameter. Using a special class of neuro-fuzzy systems i.e. Adaptive Network-based Fuzzy Interference Systems (ANFIS), we also approximate various performance measures. Finally, the conclusions and future research directions are provided.

A case study of competing risk analysis in the presence of missing data

  • Limei Zhou;Peter C. Austin;Husam Abdel-Qadir
    • Communications for Statistical Applications and Methods
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    • v.30 no.1
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    • pp.1-19
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    • 2023
  • Observational data with missing or incomplete data are common in biomedical research. Multiple imputation is an effective approach to handle missing data with the ability to decrease bias while increasing statistical power and efficiency. In recent years propensity score (PS) matching has been increasingly used in observational studies to estimate treatment effect as it can reduce confounding due to measured baseline covariates. In this paper, we describe in detail approaches to competing risk analysis in the setting of incomplete observational data when using PS matching. First, we used multiple imputation to impute several missing variables simultaneously, then conducted propensity-score matching to match statin-exposed patients with those unexposed. Afterwards, we assessed the effect of statin exposure on the risk of heart failure-related hospitalizations or emergency visits by estimating both relative and absolute effects. Collectively, we provided a general methodological framework to assess treatment effect in incomplete observational data. In addition, we presented a practical approach to produce overall cumulative incidence function (CIF) based on estimates from multiple imputed and PS-matched samples.

Prognosis after treatment with multiple dental implants under general anesthesia and sedation in a cerebral palsy patient with mental retardation: A case report

  • Hong, Young-Joon;Dan, Jung-Bae;Kim, Myung-Jin;Kim, Hyun Jeong;Seo, Kwang-Suk
    • Journal of Dental Anesthesia and Pain Medicine
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    • v.17 no.2
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    • pp.149-155
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    • 2017
  • Cerebral palsy is a non-progressive disorder resulting from central nervous system damage caused by multiple factors. Almost all cerebral palsy patients have a movement disorder that makes dental treatment difficult. Oral hygiene management is difficult and the risks for periodontitis, dental caries and loss of multiple teeth are high. Placement of dental implants for multiple missing teeth in cerebral palsy patients needs multiple rounds of general anesthesia, and the prognosis is poor despite the expense. Therefore, making the decision to perform multiple dental implant treatments on cerebral palsy patients is difficult. A 33-year-old female patient with cerebral palsy and mental retardation was scheduled for multiple implant treatments. She underwent computed tomography (CT) under sedation and the operation of nine dental implants under general anesthesia. Implant-supported fixed prosthesis treatment was completed. During follow-up, she had the anterior incisors extracted and underwent the surgery of 3 additional dental implants, completing the prosthetic treatment. Although oral parafunctions existed due to cerebral palsy, no implant failure was observed 9 years after the first implant surgery.