• International Journal of Railway
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• 제5권1호
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• pp.48-54
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• 2012

The main purpose of this study is to highlight the importance and validity of introduction of stress-concerned aptitude items for the safety critical workers, corresponding to the radical environmental change in railway industry. To attain this purpose, the author performed a brief literature survey, and scrutinized the western practice in detail. Then, the necessity of introduction of stress-related aptitude items was suggested, based on the statistics resulted from a survey which has been once performed for experts and drivers. The final conclusion is that the present selection system through which the safety critical workers are being staffed, without any rigorous screening mechanisms cannot but have some limitations. So, an overall restructuring for aptitude management system needs to be done in order for us to advance to the position of upper-class railway country.

• 대한안전경영과학회지
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• 제14권3호
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• pp.1-10
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• 2012

Recently, we have witnessed the definitely negative impacts of large-scale accidents happened in such areas as atomic power plants and high-speed train systems, which result in increased fear for the potential danger. The problems appear to arise due to the deficiency in the design of large-scale complex systems. One of the causes can be attributed to the design process that does not fully reflect the safety requirements in the early stage of the system development because of the substantially increased complexity. In this paper, to enhance the systems safety an integrated process is studied, which considers simultaneously both the system design process and system safety process from the beginning of the system development. In the conceptual system design phase an integrated process model is constructed by analyzing the activities of both the system design and safety processes. As a case study example, an inner city train system is described with the application of the developed process. The computer simulation of the example case is followed by the result discussed. The results obtained in the paper are expected to be the basis for the future study where a detailed process and its associated activities can be developed.

• 한국항행학회논문지
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• 제21권2호
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• pp.155-162
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• 2017

최근 국내에서 항공 관련 안전필수시스템들이 개발되었지만 이들 완성품들은 규정된 요구사항들을 충족시키지 못하여 실용화 또는 상용화 되지 못하였다. 현대 항공 기술의 복잡도가 높아짐에 따라 기존의 검증 및 확인 기술로는 시스템에 잠재된 리스크를 식별하고 줄이는데 어려움이 많다. 이러한 단점들을 극복하기 위해 선진국에서는 독립적 검증 및 확인이라는 새로운 기법에 관심이 모아지고 있다. 이 독립적 검증 및 확인의 효과도에 관한 학술적 연구는 국내에는 전무하고, 국외에서 조차도 매우 희소하게 수행되고 있다. 따라서 본 논문에서는 항공선진기관에서 수행한 항공 안전필수시스템에 대한 독립적 검증 및 확인의 응용 연구들을 조사하여 사업에 미치는 여러 가지 효과들을 분석해 본 결과, IV&V는 조기 오류 검출율을 높이고, 내재된 리스크도 조기에 완화하며, 개발 수명주기 후반에 나타나는 재작업 확률을 줄여서 개발 일정 및 비용의 증가를 획기적으로 막아주는 것으로 나타났다.

• International Journal of Control, Automation, and Systems
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• 제6권1호
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• pp.126-134
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• 2008

As many systems depend on electronics, concern for fault tolerance is growing rapidly. For example, a car with its steering controlled by electronics and no mechanical linkage from steering wheel to front tires (steer-by-wire) should be fault tolerant because a failure can come without any warning and its effect is devastating. In order to make system fault tolerant, there has been a body of research mainly from aerospace field. This paper presents the structure of predictive hybrid redundancy that can remove most erroneous values. In addition, several numerical simulation results are given where the predictive hybrid redundancy outperforms wellknown average and median voters.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.987-992
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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 introduces the framework for the software lifecycle. The licensing procedure for the railway software is also reviewed.

• 제어로봇시스템학회논문지
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• 제7권10호
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• pp.859-866
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• 2001

Recently, fault injection techniques are used for evaluation of the fault coverage properties of safety-critical systems. This paper describes the TCN Fault Injector(TFI) implemented for TCN safety analysis. The implemented TFI injects network level faults to Intelligent MVB Controller that is designed for the Korean High Speed Train. With TFI, it can be verified whether the MVB controller meets TCN specification and its safety requirements.

• Nuclear Engineering and Technology
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• 제47권2호
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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.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1008-1011
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• 1996

Most control systems of power plants are using classical PID controllers for their process control. In order to get the desired control performances, the correct tuning of PID controllers is very important. Sometimes, it is necessary to retune PID controllers after the change of system operating condition and system design change, etc. Commercial auto-tuning controllers such as relay feedback controller can be used for this purpose. However, using these controllers to the safety-critical systems of nuclear power plants may be cause of unsafe operation, because they are using test signals for tuning. A new system identification auto-tuning method without using test signal has been developed in this paper. This method uses process input/output signals for system identification of unknown control process. From the model information of control process which was obtained from system identification approach, the optimal PID parameters can be calculated. The method can be used in the safety-critical systems because it is not using test signals during system modeling process.

• 전기학회논문지P
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• 제59권1호
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• pp.10-17
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• 2010

Safety-critical systems related to the railway communications are currently undergoing changes. Mechanical and electro-mechanical devices are being replaced by programmable electronics that are often controlled remotely via communication networks. Therefore designers and operators now not only have to contend with component failures and user errors, but also with the possibility that malicious entities are seeking to disrupt the services provided by theirs systems. Recognizing the safety-critical nature of the types of communications required in train control operations, the communications infrastructure will be required to meet a number of safety requirements such as system faults, user errors and the robustness in the presence of malicious attackers who are willing to take determined action to interfere in the correct operation of a system. In this paper, we proposed the safety strategies employed in the railway communications and a security mechanism for Korean railway communication system. Also, we presented the developed means for validation and determination of communication safety based on the proposed security mechanism in the railway system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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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.