• Journal of Applied Reliability
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• v.2 no.2
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• pp.85-97
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• 2002

In this paper, partially repairable concurrent spare parts requirement determination problem of newly procured equipment systems is considered. “partially repairable” means that a portion of damaged parts can be recover their function and reused after repairs. A mathematical model is derived for making an CSP requirement determination subject to the constraint of satisfying any given operational availability limitation. We assume that the failure of a part follows a Poisson process and the repair time has an exponential distribution. Using the generalized Lagrange multipliers method, the solution procedure is derived.

• Proceedings of the Korean Reliability Society Conference
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• 2002.06a
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• pp.403-410
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• 2002

This paper presents the effect of internal corrosion, external corrosion, material properties, operation condition, earthquake, traffic load and design thickness in pipeline on the failure prediction using a failure probability model. A nonlinear corrosion is used to represent the loss of pipe wall thickness with time. The effects of environmental, operational, and design random variables such as a pipe diameter, earthquake, fluid pressure, a corrosion rate, a material yield stress and a pipe thickness on the failure probability are systematically investigated using a failure probability model for the corrosion pipeline.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.28 no.1
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• pp.14-21
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• 2020

Here I investigate what effects Operational Control Center(OCC)'s service quality may have on airline staff's job engagement. My analysis reveals that airline OCC's service quality has a meaningful effect on airline staff's service satisfaction, and that service satisfaction mediates a meaningful effect on staff's job engagement. It was suggested that improving OCC's service quality leads to higher staff's job engagement. Accordingly, I suggest methods of improving OCC's service quality. I find that the importance of contributing factors on OCC's service quality are as follows, in order of most to least important: professionalism, assurance, empathy, reliability, organizational culture, and responsiveness. The results of this study are relevant not only for airlines but also for government agencies such as the National Emergency Management Agency, the Korea Forest Service, the National Police Agency and the Korea Coast Guard that operate aircraft and must ensure aviation safety.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.2
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• pp.94-103
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• 2009

In relation to a certification system recently, it is coming out complains about make a rule of thumb certification, problems of after-service and duplication with government certifications. Also there is confusion in operating certification system to lack of properly rule to international standard. These impose a heavy burden on company in terms of times and costs and enhance competitiveness. Nevertheless, the survey was not built yet for the status and problems of the cooperation group standards certification System. So, this study purposes that research on the actual condition and development of operational guide for cooperation group standards certification system. In addition it ultimately improve the certification system for reliability and international competitive power. For more detail on this study, it would be considered conformity assessment, domestic/international conformity assessment and certification criteria. Also comparing survey result on the actual condition with international standards, develop operational guidelines to meet international standards.

• Nuclear Engineering and Technology
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• v.52 no.1
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• pp.135-147
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• 2020

A methodology for evaluation of mechanical and thermal effects of localized non-axisymmetric oxidation in zircaloy claddings on LWR fuel reliability is proposed. To this end, the basic capabilities of the FALCON fuel behaviour code are used. Examples of methodology application to adjustment of selected operational limits for modern BWR fuel rods, to capture effects of the excess local oxidation, are presented. Specifically, the limiting rod internal pressure for the onset of cladding lift-off is reduced, depending on initial excess oxidation spot sizes. Also, the power limits for Anticipated Operational Occurrences are adjusted, to preclude fuel melting and cladding failure due to PCMI and PCI-SCC in the affected fuel rods.

• Journal of Korea Multimedia Society
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• v.11 no.6
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• pp.891-902
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• 2008

The software once developed enters in to the $2^{nd}$ phase of its useful operational life, where it performs its functions for which it has been developed. This is an important phase of software life, wherein the developers and users have to assess the performance of the software to prolong its operational life with efficiency, effectiveness and economy. Performance of the software is based on the measurement of the quality characteristics to ascertain that it is meeting or exceeding the needs of customers in terms of its functionality, usability, efficiency, reliability, availability, maintainability, portability etc. These software quality attributes defined under ISO 9126 provide an overall good framework for assessing the performance of the software. This paper describes a Software Performance Assessment (SPA) model using the Goal-Question-Metric (GQM) paradigm which has been applied to the operational software in real context with successful results.

• Structural Engineering and Mechanics
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• v.59 no.1
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• pp.187-207
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• 2016

Practical ambient excitations of engineering structures usually do not comply with the stationary-white-noise assumption in traditional operational modal analysis methods due to heavy traffic, wind guests, and other disturbances. In order to eliminate spurious modes induced by non-white noise inputs, the improved stochastic subspace identification based on a delay index is proposed in this paper for a representative kind of stationary non-white noise ambient excitations, which have nonzero autocorrelation values near the vertical axis. It relaxes the stationary-white-noise assumption of inputs by avoiding corresponding unqualified elements in the Hankel matrix. Details of the improved stochastic subspace identification algorithms and determination of the delay index are discussed. Numerical simulations on a four-story frame and laboratory vibration experiments on a simply supported beam have demonstrated the accuracy and reliability of the proposed method in eliminating spurious modes under non-white noise ambient excitations.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.5
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• pp.637-644
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• 2010

This paper presents a reliability-based shape optimization (RBSO) using the growth-strain method. An actual design involves uncertain conditions such as material property, operational load, Poisson's ratio and dimensional variation. The purpose of the RBSO is to consider the variations of probabilistic constraint and performances caused by uncertainties. In this study, the growth-strain method was applied to shape optimization of reliability analysis. Even though many papers for reliability-based shape optimization in mathematical programming method and ESO (Evolutionary Structural Optimization) were published, the paper for the reliability-based shape optimization using the growth-strain method has not been applied yet. Growth-strain method is applied to performance measure approach (PMA), which has probabilistic constraints that are formulated in terms of the reliability index, is adopted to evaluate the probabilistic constraints in the change of average mises stress. Numerical examples are presented to compare the DO with the RBSO. The results of design example show that the RBSO model is more reliable than deterministic optimization. It was verified that the reliability-based shape optimization using growth-strain method are very effective for general structure. The purpose of this study is to improve structure's safety considering probabilistic variable.

• Journal of the Korean Society of Systems Engineering
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• v.11 no.1
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• pp.67-72
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• 2015

It has been tested for SW reliability in order to prevent the SW error during the development of weapons systems. According to a recent report, defects such as memory leak, buffer overflow, and null deference occur usually in the development stage, but also in the mass production stage. Although it is intended to enhance the SW test and evaluation to prevent SW failures in the development stage, the non-functional problems like syntax errors are not completely revised due to the limitation of the schedule and costs. In addition, SW failure rate are usually fluctuated by the operational environment through SW upgrade in contrast with HW. In this paper, we propose a method to increase SW reliability in the mass production stage of Korean weapon systems.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.198-200
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• 2005

This paper illustrates the pragram features of reliability evaluation on operation mode (operational planning and operating) of power system. The eighty eight relative reports and papers with seventeen kinds of reliability programs were Investigated in this paper. Two programs, PRA and ASSESS, were focused on the operation mode reliability evaluation program and the comparions of the two program features are introduced.