• Journal of the Korea Safety Management & Science
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• v.12 no.2
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• pp.25-33
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• 2010

Nowadays worldwide leading companies try to establish more efficient and comprehensive management system for getting high quality, reliability and safety. In this paper, we investigate standards for quality management, dependability management and risk management. We also suggest an integrated and comprehensive system of quality(ISO/TS16949), dependability (IEC60300)and risk(JIS Q2001). The evaluation method on the performance of dependability management systems are developed and applied for the semiconductor equipment company.

• Nuclear Engineering and Technology
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• v.40 no.5
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• pp.365-374
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• 2008

Dependability-critical systems, such as digital instrumentation and control systems in nuclear power plants, necessitate engineering techniques and tools to provide assurances of their safety and reliability. Determining system reliability at the architectural design phase is important since it may guide design decisions and provide crucial information for trade-off analysis and estimating system cost. Despite this, reliability and system engineering remain separate disciplines and engineering processes by which the dependability analysis results may not represent the designed system. In this article we provide an overview and application of our approach to build architecture-based, dynamic system models for dependability-critical systems and then automatically generate dynamic fault trees (DFT) for comprehensive, tool-supported reliability analysis. Specifically, we use the Architectural Analysis and Design Language (AADL) to model the structural, behavioral and failure aspects of the system in a composite architecture model. From the AADL model, we seek to derive the DFT(s) and use Galileo's automated reliability analyses to estimate system reliability. This approach alleviates the dependability engineering - systems engineering knowledge expertise gap, integrates the dependability and system engineering design and development processes and enables a more formal, automated and consistent DFT construction. We illustrate this work using an example based on a dynamic digital feed-water control system for a nuclear reactor.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.463-478
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• 2019

The most important non-functional requirements for dependability of any Embedded Real-Time Safety Systems are safety, availability and reliability requirements. System architecture plays the primary role in achieving these requirements. Compliance with these non-functional requirements should be ensured early in the development cycle with appropriate considerations during architectural design. In this paper, we present an application of system architecture modeling for quantitative assessment of system dependability. We use probabilistic model checker (PRISM), for dependability analysis of the DTMC model derived from system architecture model. In general, the model checking techniques do not scale well for analyzing large systems, because of prohibitively large state space. It limits the use of model checking techniques in analyzing the systems of practical interest. We propose abstraction based compositional analysis methodology to circumvent this limitation. The effectiveness of the proposed methodology has been demonstrated using the case study involving the dependability analysis of safety system of a large Pressurized Water Reactor (PWR).

• Nuclear Engineering and Technology
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• v.44 no.6
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• pp.663-672
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• 2012

As software based digital I&C (Instrumentation and Control) systems are used more prevalently in nuclear plants, enhancement of software dependability has become an important issue in the area of nuclear I&C systems. Critical attributes of software dependability are safety and reliability. These attributes are tightly related to software failures caused by faults. Software testing and V&V (Verification and Validation) activities are hence important for enhancing software dependability. If the risky modules of safety-critical software can be predicted, it will be possible to focus on testing and V&V activities more efficiently and effectively. It should also make it possible to better allocate resources for regulation activities. We propose a prediction technique to estimate risky software modules by adopting machine learning models based on software complexity metrics. An empirical study with various machine learning algorithms was executed for comparing the prediction performance. Experimental results show SVMs (Support Vector Machines) perform as well or better than the other methods.

• Journal of the Korea Safety Management & Science
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• v.9 no.6
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• pp.69-79
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• 2007

Corporations are faced with the key strategic task of adopting a comprehensive management system of a new paradigm in order to enhance their products' quality, safety, and reliability, as well as to minimize the cost of quality. The purpose of this paper is to present a methodology that can be used by corporations to ensure a product's reliability, safety, and maintainability, with minimal costs, by measuring dependability levels and conducting DEA analysis. The methodology will be a way for corporations to adopt an optimal dependability management system based on a quality management system of ISO 9001:2000 standards.

• Nuclear Engineering and Technology
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• v.29 no.6
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• pp.433-443
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• 1997

In this work, an analytic approach to the dependability of software in the operational phase is suggested with special attention to the hardware fault effects on the software behavior : The hardware faults considered are memory faults and the dependability measure in question is the reliability. The model is based on the simple reliability theory and the graph theory which represents the software with graph composed of nodes and arcs. Through proper transformation, the graph can be reduced to a simple two-node graph and the software reliability is derived from this graph. Using this model, we predict the reliability of an application software in the digital system (ILS) in the nuclear power plant and show the sensitivity of the software reliability to the major physical parameters which affect the software failure in the normal operation phase. We also found that the effects of the hardware faults on the software failure should be considered for predicting the software dependability accurately in operation phase, especially for the software which is executed frequently. This modeling method is particularly attractive for the medium size programs such as the microprocessor-based nuclear safety logic program.

• Journal of Advanced Navigation Technology
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• v.14 no.1
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• pp.87-92
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• 2010

The design of avionic embedded systems requires high-dependability. In this paper, we studied the dependability of the triple modular redundancy (TMR) hardware for highly reliable aviation embedded system. In order to evaluate the dependability of the base ARM processor and the TMR ARM processor, we developed the simulation model of the reduced ARM and TMR ARM processors and performed the simulation fault injection for the analysis of the dependability of the two targets. In the fault injection experiments, we calculated the error recovery rate of the two the processor models. From the experimental results, we could confirm that the reliability of the TMR ARM processor was greater than the single ARM processor by ten times in some cases.

• Journal of information and communication convergence engineering
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• v.17 no.2
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• pp.117-127
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• 2019

In software engineering, to ensure reliability between systems, describing both system architecture and assurance arguments between system elements is considered necessary. There are proposals for system architecture assurance, but use of these traditional methods often requires development of different diagrams using different editors. Because the visual sense of the traditional methods is inadequate, errors readily occur when manipulating different diagrams. Therefore, it is essential that the assurance of dependability between components and systems is visualized and easy to understand. In this paper, an integrated approach to describe the relationship between system actors and system architecture is proposed, and this approach is clarified using an enterprise architecture modeling language. A case study is carried out and comparison to the traditional approach $d^*$ framework is explained. The comparison results show that the proposed approach is more suitable for ensuring dependability in system architecture.

• Journal of Korea Multimedia Society
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• v.20 no.5
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• pp.791-799
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• 2017

With the development of the internet of things, sensor and device are can be applied to various scenario. Overall improving of the dependability index of internet of things is the ultimate goal. And reliability aims to increase the success rate of internet of things service delivery. Many studies about internet of things system have been made on the system to assess a dependability for providing reliable service to user, but it has difficult to reflect the user context for evaluating the device reliability. Also, most do not consider the availability of content information. In this paper, it proposed dependable device searching system in the internet of things environment. This system evaluates device dependability based on device status and measured data. Through the proposed system, it can be provided reliable context information for user-centric service.

• Proceedings of the Korean Society for Quality Management Conference
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• 2004.04a
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• pp.255-260
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• 2004

IEC 60300 series, the international standards on dependability management system are newly developed and introduced rapidly worldwide. In order to meet this situation, it is necessary to apply them to the Korean industries effectively. This requires for us to prepare in advance for the introduction of the certification system of IEC 60300. It includes the establishment of the infrastructure such as documentation of Korean Standards, introduction of test equipments and test manuals, recognition of the certification body and training of specialists etc. This paper addresses the first step for the Introduction of IEC 60300. It includes the necessity of introduction of the system, general requirements and procedures for the certification of the industries, sampling methods design and establishment of the dependability assurance system of the materials.