• Title/Summary/Keyword: Failure Definitions

Search Result 29, Processing Time 0.03 seconds

Performance Evaluation Involving Multiple Parameters in Built-In-Test Systems

  • Kang, Hee-Jung;Yoo, Wang-Jin
    • Journal of the Korean Operations Research and Management Science Society
    • /
    • v.16 no.2
    • /
    • pp.148-158
    • /
    • 1991
  • The Built-In-Test (BIT) system is an integrated subsystem for the determination of the health status of any primary system. The BIT consists of hardware and software installations directed at performance of the functions of fault detection, diagnosis and isolation, as well as primary system record failure information. Evaluation of the difinitions appropriate to the BIT system, including system characteristics and parameters, is important to an understanding of system functions. The object of this paper is to present general definitions of the BIT diagnosis parameters and a semiquantiative evaluation method for BIT systems. Finally, two case studies for actual problem solutions are included.

  • PDF

Determination of THRs - A Practical Approach for Manufacturers According to EN50129

  • Weber, Ulrich
    • Journal of the Korean Society for Railway
    • /
    • v.16 no.2
    • /
    • pp.104-109
    • /
    • 2013
  • The paper will outline how hazard identification and risk evaluation can effectively be performed to obtain Tolerable Hazard Rates (THR). As a target group manufacturers are addressed, who face the situation, that for a generic application THRs are needed for compliance with EN 50129 [1]. Focusing on functional hazards this paper shows a possible hazard log and the relevant analysis methods. The terms safety barrier and barrier function will be introduced and used instead of the term "safety function". As functional hazards and barrier functions depend on each other, emphasis will be put on a comprehensive and detailed definition of barrier functions and the usage of function lists. By using detailed and complete hazard and barrier function definitions THRs can be obtained while at the same time the approach becomes clear how the hazard rates (HR) will be established.

Case Study on Improvement of Reliability Prediction Accuracy in Development Phase for Aircraft (항공기 개발단계에서의 신뢰도 예측 정확도 향상에 관한 사례연구)

  • Kim, Young-Il;Byun, Kwang-Sik;Kim, Han-Tai
    • Journal of the Korean Society for Aviation and Aeronautics
    • /
    • v.17 no.4
    • /
    • pp.25-31
    • /
    • 2009
  • In development phase of the Aircraft Systems, the reliability prediction of electronic equipments are usually performed using MIL-HDBK-217. The reliability of fielded electronic systems, however, used to be underestimated with MIL-HDBK-217. To solve this problem, some alternatives are suggested and Telcordia SR-332 is among them. In this case study, the reliability of ESU which controls gas turbine engine is predicted using Telcordia SR-332 along with the development test data. The predicted reliabilities of ESU using Telcordia SR-332 and MIL-HDBK-217 are also compared. As a result this case study showed that the predicted reliability using Telcordia SR-332 was better close to field(operation) reliability than MIL-HDBK-217.

  • PDF

A Procedure for a Strength Assessment of Permanent Means of Access Structure (Permanent Means of Access 강도 평가 방법에 대한 연구)

  • Jang, Beom-Seon;Chung, Sung-Wook;Ko, Dae-En;Chun, Min-Sung;Kim, Ji-Young
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.46 no.1
    • /
    • pp.31-42
    • /
    • 2009
  • Common structural rule (CSR) doesn' t provide any other specific regulations for permanent means of access (PMA) platform structure in a cargo oil tank. The PMA platform is recommended to comply with scantling requirement of local support member. However, it leads to too conservative scantlings compared with actual loads imposed on the platform. This paper proposes a strength assessment procedure for the PMA structure based on a nonlinear ultimate strength. The ultimate strength is evaluated in a sufficiently conservative way. The first linear buckling mode is used as an initial imperfection shape and its magnitude is determined using the definitions of DNV PULS. Since the same imperfection mode as the failure mode of the ultimate limit state is assumed, it can accelerate the failure. Au ultimate strength capacity curve obtained from a series of nonlinear FE analysis is compared with actual stresses calculated by CSR cargo hold analysis.

Entering Uncharted Territory: Ownership of Healthcare by Business Corporations

  • Kim, Dongho;Youn, Myoung-Kil
    • Asian Journal of Business Environment
    • /
    • v.9 no.1
    • /
    • pp.29-31
    • /
    • 2019
  • Purpose - The aim of this paper is to examine the newly formed a partnership of Amazon, Berkshire Hathaway (Berkshire) and JPMorgan through the lens of strategic alliance, corporate philanthropy, and corporate social responsibility. Research design, data, and methodology - This is an analytical case study that examines the existing scholarly articles in strategic alliances, corporate philanthropy, and corporate social responsibility to explain the recent strategic alliance. Results - There is a clear limitation in explaining this type of unconventional strategic alliance with exiting definitions and concepts because there is no existing study or case available today. Forming a strategic business alliance to create and operate healthcare for their domestic employees could be viewed as a social innovation that resulted from an effort to resolve a social problem, the ineffective healthcare system in the U.S., rather than focusing on business benefits and profits. Conclusions - The success or failure of this type of business alliance would certainly affect the current healthcare system of the United States and global businesses and healthcare industries in the future. However, just entering or tapping into uncharted territory by these three companies to deal with a social issue is significant enough to merit further exploration and analysis for scholars and practitioners.

The Conceptual Structure of Coping -Based on Patients receiving Hemodialysis - (대처(coping)의 개념적 구조 -혈액투석환자를 대상으로-)

  • Chang Sung-Ok;Lee Sook-Ja;Kim Jung-Sook
    • Journal of Korean Academy of Fundamentals of Nursing
    • /
    • v.7 no.1
    • /
    • pp.42-59
    • /
    • 2000
  • This study was done to analyze and develop the concept of coping in patients receiving hemodialysis. The Hybrid Model of concept development was applied to develop a conceptual structure of coping in patients receiving hemodialysis, which included a field study carried out using an in-dept interview with 18 patients in the hemodialysis room of one general hospital in Seoul. Data-analysis was done in three phases as suggested by the Hybrid Model. Finally, by summarizing the results from each case, the attributes of coping, its dimensions, definition and structure were outlined. According to the results of the study, a conceptual structure of coping which centers around stressors, stress-appraisal, strategy of coping and new definitions of coping in patients receiving hemodialysis was suggested : The coping of patients receiving hemodialysis is a process that deals with physical, emotional, inter-personal, and role stress caused by hemodialysis due to renal failure. It has a series of phases which include a phase that appraises the stressful situation based on past experience of chronic disease management, one's remaining rears, the extent of family support, the extent of economic dependency, inter-personal support. education and uncertainty, and a phase of developing coping strategies that con be affected by social support and self esteem. As a result of coping, patients adapt or not to the life situation of receiving hemodialysis.

  • PDF

Reliability Analysis of Interconnected Dynamical Systems with Reconfigurable Control

  • Matsumoto, Satoshi;Kohda, Takehisa
    • International Journal of Safety
    • /
    • v.10 no.2
    • /
    • pp.10-15
    • /
    • 2011
  • The reconfigurable control systems based on feedback controls are utilized to compensate for damages of actuators in control systems. Such systems have multiple feedback controls and switch them in accordance with the degrees of the failures of the actuators. In order to be able to assess those systems, this paper develops a method to obtain reliabilities of reconfigurable dynamical systems which are interconnected in parallel / series configuration. By calculating reliabilities of interconnected dynamical systems, it is possible to assess many dynamical systems by comparing their reliabilities. Firstly, reliabilities of subsystems are obtained according to the definitions of the failures in terms of robust reliability for each subsystem. Then, the reliability of overall system is calculated from reliabilities of subsystems, using the methodology employed for probabilistic safety assessment. Failure rates of subsystems with feedbacks for reconfiguration change in certain time periods because of the switching of feedback controls. In order to deal with this, combinations of subsystems which compose overall system for each time period are derived by the methodology mentioned above and then integrated to calculate the reliability of overall system for a specific time. An illustrative example shows the validity and details of the proposed method.

  • PDF

Sepsis: Early Recognition and Optimized Treatment

  • Kim, Hwan Il;Park, Sunghoon
    • Tuberculosis and Respiratory Diseases
    • /
    • v.82 no.1
    • /
    • pp.6-14
    • /
    • 2019
  • Sepsis is a life-threatening condition caused by infection and represents a substantial global health burden. Recent epidemiological studies showed that sepsis mortality rates have decreased, but that the incidence has continued to increase. Although a mortality benefit from early-goal directed therapy (EGDT) in patients with severe sepsis or septic shock was reported in 2001, three subsequent multicenter randomized studies showed no benefits of EGDT versus usual care. Nonetheless, the early administration of antibiotics and intravenous fluids is considered crucial for the treatment of sepsis. In 2016, new sepsis definitions (Sepsis-3) were issued, in which organ failure was emphasized and use of the terms "systemic inflammatory response syndrome" and "severe sepsis" was discouraged. However, early detection of sepsis with timely, appropriate interventions increases the likelihood of survival for patients with sepsis. Also, performance improvement programs have been associated with a significant increase in compliance with the sepsis bundles and a reduction in mortality. To improve sepsis management and reduce its burden, in 2017, the World Health Assembly and World Health Organization adopted a resolution that urged governments and healthcare workers to implement appropriate measures to address sepsis. Sepsis should be considered a medical emergency, and increasing the level of awareness of sepsis is essential.

A Review on Urban Resilience Assessment Methods

  • Barjau, Jaime;Wong, Francis K.W.;Fang, Dongping
    • International conference on construction engineering and project management
    • /
    • 2015.10a
    • /
    • pp.685-686
    • /
    • 2015
  • The world is currently undergoing an intense urbanization process. The percentage of urban dwellers has never been so high. In 2010, and for the first time, urban population surpassed the rural one, accounting for 51% of global population, and this trend will continue in the forthcoming years. This increment in concentration of population and supporting assets in cities, make their performance a critical issue for world population. Recent events such as Fukushima tsunami and the hurricane Katrina have shown how fragile built environments are and the unpredictability of occurrence and magnitude of the hazards. Such an expansion of the world's urban population, together with an increase in severity and number of hazards and catastrophes, has put under the spotlight the necessity to build cities not only sustainable, but resilient. Decision makers should acknowledge failure as an option, and the importance of developing city resilience. This paper will provide an initial review on urban resilience, definitions and assessment approaches as a first step for decision makers to account for resilience in their decision making process.

  • PDF

MEASURING THE INFLUENCE OF TASK COMPLEXITY ON HUMAN ERROR PROBABILITY: AN EMPIRICAL EVALUATION

  • Podofillini, Luca;Park, Jinkyun;Dang, Vinh N.
    • Nuclear Engineering and Technology
    • /
    • v.45 no.2
    • /
    • pp.151-164
    • /
    • 2013
  • A key input for the assessment of Human Error Probabilities (HEPs) with Human Reliability Analysis (HRA) methods is the evaluation of the factors influencing the human performance (often referred to as Performance Shaping Factors, PSFs). In general, the definition of these factors and the supporting guidance are such that their evaluation involves significant subjectivity. This affects the repeatability of HRA results as well as the collection of HRA data for model construction and verification. In this context, the present paper considers the TAsk COMplexity (TACOM) measure, developed by one of the authors to quantify the complexity of procedure-guided tasks (by the operating crew of nuclear power plants in emergency situations), and evaluates its use to represent (objectively and quantitatively) task complexity issues relevant to HRA methods. In particular, TACOM scores are calculated for five Human Failure Events (HFEs) for which empirical evidence on the HEPs (albeit with large uncertainty) and influencing factors are available - from the International HRA Empirical Study. The empirical evaluation has shown promising results. The TACOM score increases as the empirical HEP of the selected HFEs increases. Except for one case, TACOM scores are well distinguished if related to different difficulty categories (e.g., "easy" vs. "somewhat difficult"), while values corresponding to tasks within the same category are very close. Despite some important limitations related to the small number of HFEs investigated and the large uncertainty in their HEPs, this paper presents one of few attempts to empirically study the effect of a performance shaping factor on the human error probability. This type of study is important to enhance the empirical basis of HRA methods, to make sure that 1) the definitions of the PSFs cover the influences important for HRA (i.e., influencing the error probability), and 2) the quantitative relationships among PSFs and error probability are adequately represented.