• Nuclear Engineering and Technology
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• v.41 no.6
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• pp.849-858
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• 2009

Risk caused by safety-critical instrumentation and control (I&C) systems considerably affects overall plant risk. As digitalization of safety-critical systems in nuclear power plants progresses, a risk model of a digitalized safety system is required and must be included in a plant safety model in order to assess this risk effect on the plant. Unique features of a digital system cause some challenges in risk modeling. This article aims at providing an overview of the issues related to the development of a static fault-tree-based risk model. We categorize the complicated issues of digital system probabilistic risk assessment (PRA) into four groups based on their characteristics: hardware module issues, software issues, system issues, and safety function issues. Quantification of the effect of these issues dominates the quality of a developed risk model. Recent research activities for addressing various issues, such as the modeling framework of a software-based system, the software failure probability and the fault coverage of a self monitoring mechanism, are discussed. Although these issues are interrelated and affect each other, the categorized and systematic approach suggested here will provide a proper insight for analyzing risk from a digital system.

• Journal of KIISE:Software and Applications
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• v.31 no.6
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• pp.750-759
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• 2004

The software of the nuclear power plant digital control system is a safety-critical system where many techniques must be applied to it in order to preserve safety in the whole system. Formal specifications especially allow the system to be clearly and completely specified in the early requirements specification phase therefore making it a trusted method for increasing safety. In this paper, we discuss the NuSCR, which is a qualified formal specification method for specifying nuclear power plant digital control system software requirements. To investigate the application of NuSCR, we introduce the experience of using NuSCR in formally specifying the plant protection system's software requirements, which is presently being developed at KNICS. Case study that shows that the formal specification approach NuSCR is very much qualified and specialized for the nuclear domain is also shown.

• Journal of Advanced Navigation Technology
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• v.28 no.4
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• pp.466-471
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• 2024

Recently, the Machine Learning based Artificial Intelligence has introduced in aviation field. In most cases, safety assurance of aviation software is achieved by applying RTCA DO-178C or DO-278A or similar standards. These standards were developed for and are well-suited to software that has inherent deterministic properties and explainability. Considering the characteristics of AI software based on ML, it is not feasible to assure the integrity of those new aviation systems using traditional software assurance standards mentioned above. In this paper, we research the certification framework that is newly suggested by EASA to deal with the aviation system including ML AI functions, and discuss what should the Korean authority and related industries prepare to cope with this issue.

• IE interfaces
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• v.25 no.4
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• pp.416-421
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• 2012

One of the activities to improve software quality in ISO 26262 is to apply the design principles for software unit design and implementation mentioned in ISO 26262-6, including the evaluation activity. Before evaluation activity, the tool is compared and selected for evaluation. Because the results of the tool a company selected might have an effect on product quality. In this paper, we suggest the method to compare industrial static analysis tools with some of "MISRA C : 2004 Exemplar Suite" and all lessons learned from comparing tools are described. The result on comparison shows that we just couldn't rely on a result of Static Analysis Tool and need to have another appropriate processes and guidelines to evaluate a software.

• Journal of the Korean Society for Railway
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• v.9 no.5 s.36
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• pp.601-605
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• 2006

Reliability of the Railway signaling system which is safety critical is determined by reliability of hardware and software. Reliability of hardware is easily predicted and demonstrated through lots of different studies and environmental tests, while that of software is estimated by the iterative test outcomes so estimates of reliability will depend on the inputs. Combinations of inputs to and outputs from the software may be mostly combinatoric and therefore all the combinations could not be tested. As a result, it has been more important to calculate reliability by means of a simpler method. This paper identifies the reliability prediction equation applicable to reliability prediction for railway signaling system software, and performs the simulation of onboard equipment of automatic train control for high speed train to review reliability prediction and validity.

• Nuclear Engineering and Technology
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• v.31 no.1
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• pp.49-57
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• 1999

It has been a critical issue to predict the safety critical software reliability in nuclear engineering area. For many years, many researches have focused on the quantification of software reliability and there have been many models developed to quantify software reliability. Most software reliability models estimate the reliability with the failure data collected during the test assuming that the test environments well represent the operation profile. User's interest is however on the operational reliability rather than on the test reliability. The experiences show that the operational reliability is higher than the test reliability. With the assumption that the difference in reliability results from the change of environment, from testing to operation, testing environment factors comprising the aging factor and the coverage factor are developed in this paper and used to predict the ultimate operational reliability with the failure data in testing phase. It is by incorporating test environments applied beyond the operational profile into testing environment factors. The application results show that the proposed method can estimate the operational reliability accurately.

• Communications of the Korean Institute of Information Scientists and Engineers
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• v.30 no.2
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• pp.62-71
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• 2012

• KIPS Transactions on Software and Data Engineering
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• v.6 no.12
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• pp.543-548
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• 2017

In recent years, the importance of the safety of medical device software has been emphasized because of the function and role of the software among components of the medical device, and because the operation of the medical device software is directly related to the life and safety of the user. To this end, various standards have been set up that provide activities that can effectively ensure the safety of medical devices and provide their respective requirements. The activities that standards provide to ensure the safety of medical device software are largely divided into the development life cycle of medical device software and the risk management process. These two activities should be concurrent with the development process, but there is a limitation that the risk management requirements to be performed at each stage of the medical device software development life cycle are not classified. As a result, developers must analyze the association of standards directly to develop risk management activities during the development of medical devices. Therefore, in this paper, we analyze the relationship between medical device software development life cycle and risk management process, and extract risk management requirement items. It enables efficient and systematic risk management during the development of medical device software by mapping the extracted risk management requirement items to the development life cycle based on the analyzed associations.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1467-1473
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• 2004

It requires different safety programs from those of the typical train control systems to develop AGT systems applying train control system based on communication technology. Especially Advanced LRT system involves the processes that have the various safety functions being conducted by softwares and also have characteristics that should have special interest in validation of interface specification. The core items for the safety engineering for LRT control systems are hardware & software engineering, safety-critical system safety engineering, application software validation & verification technologies. In this paper the trends of the technologies for the mentioned core-items are described.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.982-989
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• 2005

Safety of the Train Control System become more important along with the progress of the computer and the technology of communications in these days. Safety of the Train Traffic Control System needs an accurate analysis of the Hazard to reduce losses of a property and lives. Many of advanced railroad nations already had established safety standards when they set the system even considering scrap of railroad and put a great concern on developing safety system which is getting larger and more complicate. Domestic railroad system has to introduce improved technology and systematically prepare and make a scientific survey to achieve unparalleled reliability and safety as well. In this Study, ITCC CTC System will show the research and the analysis of the hazard to ensure the safety of software.