• Journal of the Korean Society for Railway
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• v.20 no.1
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• pp.55-63
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• 2017

Railway interlocking systems which are safety-critical systems are rapidly changed from relay-based systems to computer-based systems which have high flexible. Computer-based interlocking systems (CBI) are consisted of hardware and software in which system safeties arise one of important problems. The interlocking software of the CBI influences directly to the system safeties. "z" notation is one of formal methods have been used for system software specification to secure system safety. In this paper, the specification of interlocking logics for CBI systems is realized using "z" notation and verifies it with Z/EVES.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.968-973
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• 2007

The systems such as the railway control system, satellite control system and nuclear power plant control system are the safety critical systems because the failure of them could lead to risk significant events. These softwares of digital systems must follow the life cycle process from the beginning of software development to guarantee their safety and reliability. The NRC(Nuclear Regulatory Commission) Reg Guide of nuclear fields, the RTCA/DO-178B standard which is used to acquire the certification for software in industrial aero field in European Union and United State, the DEF STAN 00-55 standard for the safety of electronic weapon in England, the IEC 601-1-4 for medical equipment and the IEC 62279 for railway system recommended the development life cycle. This paper introduces the development process and compares each other. Also it indicates applicable development criteria for the software of systems related to railway fields and describes the detailed procedure of development criteria. We describe the procedure to make the software development criteria in nuclear filed. For the software development related to railways, the process from plan phase to maintenance phase must be satisfied. The safety and reliability is guaranteed through these standards.

• Journal of Computing Science and Engineering
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• v.11 no.1
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• pp.9-23
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• 2017

NuDE 2.0 (Nuclear Development Environment 2.0) is a formal-method-based software development, verification and safety analysis environment for safety-critical digital I&Cs implemented with programmable logic controller (PLC) and field-programmable gate array (FPGA). It simultaneously develops PLC/FPGA software implementations from one requirement/design specification and also helps most of the development, verification, and safety analysis to be performed mechanically and in sequence. The NuDE 2.0 now consists of 25 CASE tools and also includes an in-depth solution for indirect commercial off-the-shelf (COTS) software dedication of new FPGA-based digital I&Cs. We expect that the NuDE 2.0 will be widely used as a means of diversifying software design/implementation and model-based software development methodology.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.316-318
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• 2006

It can be considered that the safety of software is combined with that of hardware, and also directly connected to system safety. Because the software in the railway system takes the form of Embedded that let it behave at the system level, instead of independent operation, the safety of the railway S/W is also important. The approach, for ensuring the quality and safety of those software, can be considered with two points of view. Those are views seeing from products, and from processes. The two points of approach are all necessary in the railway system. For the first of all, the process approach is to validate maturity of the organizations in accordance to the judging processes of organizations, which are specified by CMMI(Capability Maturity Model Integration) or SPICE(Software Process Improvement and Capability dEtermination: ISO/IECl5504). In this paper, as the first step of them, we are trying to find approaches to estimate the maturity of manufacturer and assessment organization in the railway system.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.24 no.2
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• pp.81-85
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• 2016

It is recognized that safety is a key point of technical competency. Its adoption is widely spread in development of products and it is essentially necessary in aerospace industry because airborne system and equipment are used complex high-technology and implemented systematic performance using software. This study reviews system safety assessment, development assurance level, airborne software, RTCA DO-178 process, and considerations & pitfalls in software development.

• Journal of Information Processing Systems
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• v.14 no.2
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• pp.309-321
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• 2018

In the conventional computing environment, users use only a small number of software systems intensively. So it had been enough to check and guarantee the functional correctness and safety of a small number of giant systems in order to protect the user systems and their information inside the systems from outside attacks. However, checking the correctness and safety of giant systems is not enough anymore, since users are using various software systems or web services provided by unskilled developers. To prove or guarantee the safety of software system, a lot of research has been conducted in diverse areas of computer science. We will discuss the on-going approaches for guaranteeing or verifying the safety of software systems in this paper. We also discuss the future research challenge which must be solved with better solutions in the near future.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.201-203
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• 2007

Safety critical systems are those in which a failure can have serious and irreversible consequences. Nowadays digital technology has been rapidly applied to critical system such as railways, airplanes, nuclear power plants, vehicles. The main difference between analog system and digital system is that the software is the key component of the digital system. The digital system performs more varying and highly complex functions efficiently compared to the existing analog system because software can be flexibly designed and implemented. The flexible design make it difficult to predict the software failures. This paper reviews safety standard and criteria for safety critical system such as railway system and suggests software development methodology for more detail description.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.204-206
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• 2007

The portion of embedded software in railway signaling system is increased by the advance of computer and communication technology. And the safely requirements for railway system are standardized by int'l std., such as IEC 62278 and IEC 62279. According to these circumstances for software safety problems, we are deduced the testing items for software safety test and assessment for railway signaling. Testing tools used for embedded software are surveyed to find a feasible safety assessment architecture. And the architecture of automatic test tool is proposed to test the deduced safely testing items in this paper.

• Nuclear Engineering and Technology
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• v.47 no.2
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• pp.212-218
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• 2015

We describe a comparative analysis of different tools used to assess safety-critical software used in nuclear power plants. To enhance the credibility of safety assessments and to optimize safety justification costs, $Electricit{\acute{e}}$ de France (EDF) investigates the use of methods and tools for source code semantic analysis, to obtain indisputable evidence and help assessors focus on the most critical issues. EDF has been using the PolySpace tool for more than 10 years. Currently, new industrial tools based on the same formal approach, Abstract Interpretation, are available. Practical experimentation with these new tools shows that the precision obtained on one of our shutdown systems software packages is substantially improved. In the first part of this article, we present the analysis principles of the tools used in our experimentation. In the second part, we present the main characteristics of protection-system software, and why these characteristics are well adapted for the new analysis tools. In the last part, we present an overview of the results and the limitations of the tools.

• Journal of Digital Contents Society
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• v.18 no.2
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• pp.393-401
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• 2017

As the importance of software in various industry areas has been increased, the number of accidents related to software safety are growing up. The key industries such as railroads, aviation and medicine, recommend IEC 61508 and international safety standards for their own to achieve functional safety and reduce the issues caused by that. For equipment of ship navigation, there are not any particular standards or guidance which Korean users can introduce as considering software functional safety. This article defines the procedure and outcomes of the risk analysis in order to secure software functional safety in marine navigational equipment and applies them to an echo sounder as a case study.