• Title, Summary, Keyword: Failure Definitions

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A Definition and Evaluation Criteria for Software Development Success (소프트웨어 개발 성공의 정의와 평가기준)

  • Lee, Sang-Un;Choi, Myeong-Bok
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.12 no.2
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    • pp.233-241
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    • 2012
  • The object of the project management is to succeed in the project. However, could you definitely judge that the result of project performance is a success? In addition, do both customer and developer agree with the result of your judgement? There are a lot of definitions and measure for the success and failure of the software development suggested, but there is no definite standard for the classification. This paper examines the measures in order to decide the development success and re-defines the success and the failure of the project. We suggest the measure and the standard that judge the project achievement based on these definitions. Applying the suggested measure and standard, it is possible to reduce arguments between the customer and the developer on the classification of the success and the failure.

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 Study on the Failure Definition for the MTBF Evaluation (MTBF 평가를 위한 고장정의 소고)

  • Kim, Cheol
    • IE interfaces
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    • v.1 no.2
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    • pp.67-74
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    • 1988
  • MTBF (Mean Time Between Failures) is one of the measures to express the reliability for a repairable system, especially for a military weapon system. But MTBF is meaningless without a clear definition of the system failures. In this paper we discuss two failure definitions, one is defined by US Army Training and Doctrine Command jointly with US Army Materiel Command and the other one is used to M1 Tank.

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Patterns of initial failure after resection for gallbladder cancer: implications for adjuvant radiotherapy

  • Kim, Tae Gyu
    • Radiation Oncology Journal
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    • v.35 no.4
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    • pp.359-367
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    • 2017
  • Purpose: This study sought to identify potential candidates for adjuvant radiotherapy and patterns of regional failure in patients who underwent curative-intent surgery for gallbladder cancer. Materials and Methods: Records for 70 patients with gallbladder cancer who underwent curative resection at a single institution between 2000 and 2016 were analysed retrospectively. No patients received adjuvant radiotherapy. Initial patterns of failure were evaluated. Regional recurrence was categorized according to the definitions of lymph node stations suggested by the Japanese Society of Hepato-Biliary-Pancreatic Surgery. Results: Median follow-up was 23 months. Locoregional recurrence as any component of first failure occurred in 29 patients (41.4%), with isolated locoregional recurrence in 13 (18.6%). Regional recurrence occurred in 23 patients, and 77 regional recurrences were identified. Commonly involved regional stations were #13, #12a2, #12p2, #12b2, #16a2, #16b1, #9, and #8. Independent prognostic factors for locoregional recurrence were ${\geq}pT2$ disease (hazard ratio [HR], 5.510; 95% confidence interval [CI], 1.260-24.094; p = 0.023) and R1 resection (HR, 6.981; 95% CI, 2.378-20.491; p < 0.001). Conclusion: Patients with pT2 disease or R1 resection after curative surgery for gallbladder cancer may benefit from adjuvant radiotherapy. Our findings on regional recurrence may help physicians construct a target volume for adjuvant radiotherapy.

Treatment of Mycobacterium avium Complex Pulmonary Disease

  • Kwon, Yong-Soo;Koh, Won-Jung;Daley, Charles L.
    • Tuberculosis and Respiratory Diseases
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    • v.82 no.1
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    • pp.15-26
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    • 2019
  • The pathogen Mycobacterium avium complex (MAC) is the most common cause of nontuberculous mycobacterial pulmonary disease worldwide. The decision to initiate long-term antibiotic treatment is difficult for the physician due to inconsistent disease progression and adverse effects associated with the antibiotic treatment. The prognostic factors for the progression of MAC pulmonary disease are low body mass index, poor nutritional status, presence of cavitary lesion(s), extensive disease, and a positive acid-fast bacilli smear. A regimen consisting of macrolides (clarithromycin or azithromycin) with rifampin and ethambutol has been recommended; this regimen significantly improves the treatment of MAC pulmonary disease and should be maintained for at least 12 months after negative sputum culture conversion. However, the rates of default and disease recurrence after treatment completion are still high. Moreover, treatment failure or macrolide resistance can occur, although in some refractory cases, surgical lung resection can improve treatment outcomes. However, surgical resection should be carefully performed in a well-equipped center and be based on a rigorous risk-benefit analysis in a multidisciplinary setting. New therapies, including clofazimine, inhaled amikacin, and bedaquiline, have shown promising results for the treatment of MAC pulmonary disease, especially in patients with treatment failure or macrolide-resistant MAC pulmonary disease. However, further evidence of the efficacy and safety of these new treatment regimens is needed. Also, a new consensus is needed for treatment outcome definitions as widespread use of these definitions could increase the quality of evidence for the treatment of MAC pulmonary disease.

Nonlinear finite element modelling of centric dowel connections in precast buildings

  • Zoubek, Blaz;Fahjan, Yasin;Fischinger, Matej;Isakovic, Tatjana
    • Computers and Concrete
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    • v.14 no.4
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    • pp.463-477
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    • 2014
  • The modelling approach in the case of connections in precast buildings is specific. The assembly of the constitutive parts of the connection requires the inclusion of contact definitions in the model. In addition, the material non-linearity including the influence of the spatial stress distribution should be taken into account where appropriate. Here a complex model of a beam-to-column dowel connection is presented. Experiments on the analysed connection were performed within the framework of the European project SAFECAST (Performance of Innovative Mechanical Connections in Precast Building Structures under Seismic Conditions). Several material and interaction parameters were investigated and the influence of each of them was evaluated. The set of parameters which gave the best match with the experiments was chosen.

On Reliability Performance of Safety Instrumented Systems with Common Cause Failures in IEC 61508 Standard (공통원인고장을 고려한 안전제어시스템의 신뢰성 평가척도에 관한 고찰 : IEC 61508을 중심으로)

  • Seo, Sun-Keun
    • IE interfaces
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    • v.25 no.4
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    • pp.405-415
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    • 2012
  • The reliability performance measures for low and high or continuous demand modes of operation of safety instrumented systems(SISs) are examined and compared by analyzing the official definitions in IEC 61508 standard. This paper also presents a status of common cause factor(CCF) models used in IEC 61508 and problems relating CCF modelling are discussed and ideas to solve these ones are suggested. An example with mixed M-out-of-N architecture is carried out to illustrate the proposed methods.

Improving the Reliability of a Reciprocating Compressor for Applications in a Refrigerator

  • Woo, Seong-Woo;Chu, Yong-Ho;Ahn, Haeng-Keun
    • Korean Journal of Materials Research
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    • v.17 no.11
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    • pp.580-586
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    • 2007
  • To enhance the reliability of a newly designed reciprocating compressor applied in a domestic compressor, accelerated life tests were developed using new definitions of the sample size and the $B_1$ life index. In $1^{st}$ accelerated life testing, the compressor was locked due to the fracture of the suction reed valve. The failure modes and mechanisms of the suction reed valve in the accelerated tests were found to be similar to that of the failed product in the field. The root cause of the failure was the overlap between the suction reed valve and the valve plate in the suction port. The missing parameters in the design phase were modified by expanding the trespan size, introducing tumbling process, changing the material and thickness for the valve, introducing a ball peening and brushing process for the valve plate. In $2^{nd}$ accelerated life testing, the compressor was locked due to the interference between the crank shaft and thrust washer. The corrective plan was to heat treat the crank shaft. The $B_1$ life of the compressor improved from 1.5 to 12.9 years.

Systems Thinking Perspective on the Organizational Safety Culture of Nuclear Power Plants in Korea (원자력발전소 조직 안전문화에 관한 시스템 사고적 고찰)

  • Oh, Youngmin
    • Korean System Dynamics Review
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    • v.15 no.1
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    • pp.51-74
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    • 2014
  • Despite the high efficiency of nuclear power plant, people in Korea do not give approvals and supports the facilities because the risk of the accidents and incidents. In particular, the low level of safety culture is a crucial mechanism that damages the robustness of the NPP. By considering the various definitions of safety culture and analyzing the major reasons of incidents, the conceptual safety culture model is made by using Causal Loop Diagramming. For sustaining development of nuclear power, social supports, incentives and organizational learning are needed. It also requires the coordination of work schedules and the expansion of human resource for protecting the rules and procedures in NPP. Decommissioning aging nuclear power plants will prevent a serious accident. In order to promote the safety culture, Korea Hydro & Nuclear Power Corporation should disclose more information to the public and promote the internal and external communications.

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Reliability Analysis of Interconnected Dynamical Systems with Reconfigurable Control

  • Matsumoto, Satoshi;Kohda, Takehisa
    • International Journal of Safety
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    • v.10 no.2
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    • pp.10-15
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    • 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.

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