• Title/Summary/Keyword: Safety Critical Software

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A study on the Correlation Hazard Analysis for Signaling System Safety (안전성 확보를 위한 위험원 분석 기법간 상관관계에 대한 연구)

  • Han, Chan-Hee;Lee, Young-Soo;Ahn, Jin;Jo, Woo-Sic
    • Proceedings of the KSR Conference
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    • 2007.11a
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    • pp.638-645
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    • 2007
  • Computers are increasingly being introduced into safety and reliability critical systems. The safe and reliable operation of these systems cannot be taken for granted. Malfunctions of these systems can have potentially catastrophic consequences and they have already been involved in serious accidents. Software fault prevention, fault tolerance, fault removal and fault forecasting are the techniques to be used, implemented and verified for embedded software in critical systems as the contributors to safety and reliability of the software. To use them when developing a software product, a relationship must be established between them and the development processes, the methods and techniques to be used to develop software, as well as with the different product architectures. Railroad signaling system software is a safety-critical embedded software with realtime and high reliability requirements. The primary purpose of the safety management is to prevent the loss of lives or physical damages arising from potential hazards in the railroad signaling system. This study provides a systematic approach to analysis of potential hazards for their management during the system life cycle to assure the identification and definition of the most appropriate hazards.

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A Study on the Achieving Software Quality in Nuclear Field (원전의 컴퓨터 소프트웨어 품질확보 방안 고찰)

  • 고한준;오연우
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.19 no.38
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    • pp.61-68
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    • 1996
  • Quality Assurance Principles must be effectively implemented in developments and in use of safety critical software in nuclear industry. Brief definitions related to computer software and quality assurance were defined and several methods for evaluating software quality were proposed herewith. Independent verification and validation was suggested to assure the quality of safety critical software.

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Study on Z specification for S/W Safety of Computer Based Interlocking Systems (전자연동장치 S/W 안전성 확보를 위한 Z 방법표현에 관한 연구)

  • Ahn, Jin;Lee, Jongwoo
    • 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.

Suggestion of Systematic Approach for Developing Railway Software (철도소프트웨어의 개발을 위한 체계적 접근법 제안)

  • Joung, Eui-Jin;Shin, Kyung-Ho
    • Proceedings of the KIEE Conference
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    • 2008.04c
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    • pp.158-160
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    • 2008
  • 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, and 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 development methodology, ordering management and assessment process for railway software with more detail description.

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Suggestion of Ordering and Assessment Process for Railway Software (철도소프트웨어 발주 및 평가프로세스 제안)

  • Joung, Eui-Jin;Shin, Kyung-Ho
    • Proceedings of the KIEE Conference
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    • 2008.07a
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    • pp.1014-1015
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    • 2008
  • 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, and 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 development process, ordering management and assessment process for railway software with more detail description.

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Development of simulation-based testing environment for safety-critical software

  • Lee, Sang Hun;Lee, Seung Jun;Park, Jinkyun;Lee, Eun-chan;Kang, Hyun Gook
    • Nuclear Engineering and Technology
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    • v.50 no.4
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    • pp.570-581
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    • 2018
  • Recently, a software program has been used in nuclear power plants (NPPs) to digitalize many instrumentation and control systems. To guarantee NPP safety, the reliability of the software used in safetycritical instrumentation and control systems must be quantified and verified with proper test cases and test environment. In this study, a software testing method using a simulation-based software test bed is proposed. The test bed is developed by emulating the microprocessor architecture of the programmable logic controller used in NPP safety-critical applications and capturing its behavior at each machine instruction. The effectiveness of the proposed method is demonstrated via a case study. To represent the possible states of software input and the internal variables that contribute to generating a dedicated safety signal, the software test cases are developed in consideration of the digital characteristics of the target system and the plant dynamics. The method provides a practical way to conduct exhaustive software testing, which can prove the software to be error free and minimize the uncertainty in software reliability quantification. Compared with existing testing methods, it can effectively reduce the software testing effort by emulating the programmable logic controller behavior at the machine level.

Development Methodology of Safety-Critical System Using Formal Method (정형기법을 이용한 Safety-Critical System 개발 방법론)

  • 성창훈;이나영;오승록;최진영
    • Proceedings of the Korean Information Science Society Conference
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    • 2000.10a
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    • pp.486-488
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    • 2000
  • 본 연구는 정형기법을 사용하여 Safety-Critical System의 개발 방법론을 제시한다. Safety-Critical System의 전체적인 개발 과정을 제시하고 Safety-Critical System 중의 하나인 원자력 발전소 시스템 중 Reactor Protection System(RPS)을 정형 명세(Formal Specification)하고 정형 검증(Formal Verification)하는 과정과 그에 따른 각 과정의 Compliance를 확인하는 예를 든다. 여기서 정형 명세에는 Software Cost Reduction(SCR)이하는 도구가 사용되었고, 정형 검증에는 SPIN이, Compliance를 확인하는 데에는 Prototype Verification System(PVS)를 사용하였다.

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EVALUATION OF STATIC ANALYSIS TOOLS USED TO ASSESS SOFTWARE IMPORTANT TO NUCLEAR POWER PLANT SAFETY

  • OURGHANLIAN, ALAIN
    • 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.

A Quantitative Study on Important Factors of the PSA of Safety-Critical Digital Systems

  • Kang, Hyun-Gook;Taeyong Sung
    • Nuclear Engineering and Technology
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    • v.33 no.6
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    • pp.596-604
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    • 2001
  • This paper quantitatively presents the effects of important factors of the probabilistic safety assessment (PSA) of safety-critical digital systems. The result which is quantified using fault tree analysis methodology shows that these factors remarkably affect the system safety. In this paper we list the factors which should be represented by the model for PSA. Based on the PSA experience, we select three important factors which are expected to dominate the system unavailability. They are the avoidance of common cause failure, the coverage of fault tolerant mechanisms and software failure probability. We Quantitatively demonstrate the effect of these three factors. The broader usage of digital equipment in nuclear power plants gives rise to the safety problems. Even though conventional PSA methods are immature for applying to microprocessor-based digital systems, practical needs force us to apply it because the result of PSA plays an important role in proving the safety of a designed system. We expect the analysis result to provide valuable feedback to the designers of digital safety- critical systems.

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Safety Assessment of Train Control System Software (열차제어시스템 소프트웨어 안전성 평가기법)

  • Han, Jae-Joong;Cho, Byung-Tae;Hwang, Jong-Gyu;Jo, Hyun-Jeong;Kim, Hyung-Shin
    • Proceedings of the KSR Conference
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    • 2007.05a
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    • pp.272-279
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    • 2007
  • Recently, train control system is adopting computer system replacing mechanical system and its software is taking more responsibility than ever. Train control system software is a safety-critical embedded software with realtime and high reliability requirements. In this paper, we propose a safety assessment method for the train control system software. We review characteristics of train control system software and analyze related international software safety standards to derive requirements for safety assessment. Testing tools used for embedded software are surveyed to find a feasible safety assessment architecture. The proposed safety assessment method is to use safety activity results generated during development processes and feed them to the runtime embedded software testing tool.

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