• Nuclear Engineering and Technology
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• v.53 no.10
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• pp.3319-3326
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• 2021

As a form of industrial control systems (ICS), nuclear instrumentation and control (I&C) systems have been digitalized increasingly. This has raised in turn cyber security concerns. Cyber security for ICS is important because cyber-attacks against ICS can cause not only equipment damage and loss of production but also personal and public safety hazards unlike in general IT environments. Numerous risk analyses have been carried out to enhance the safety of ICS and recently, many studies related to the cyber security of ICS are being conducted. Many existing risk analyses and cyber security studies have considered safety and cyber security separately. However, both safety and cyber security perspectives should be considered when analyzing risks for complex and critical ICS facilities such as nuclear power plants (NPPs). In this paper, the STPA-SafeSec methodology is selected to consider both safety and security perspectives when performing a risk analysis for NPPs in order to assess impacts on the safety by cyber-attacks against the digital I&C systems. The STPA-SafeSec methodology was applied to a test-bed system that simulates a condensate water (CD) system in an NPP. The process of the application up to the development of mitigation strategies is described in detail.

• 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 the Korean Society of Industry Convergence
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• v.20 no.4
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• pp.313-323
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• 2017

As vehicles become more intelligent this is focused on ways to enhance safety and convenience for both drivers and passengers. In particular, x-by-wire systems that replace rigid mechanical components with dynamically configurable electronic elements are being developed to expand intelligent functions, such as adaptive cruise control or lane departure warning system. Because the malfunction of safety-related modules controlling critical functions, such as brakes, throttle, and steering in x-by-wire systems, can cause injury or death, safety and reliability are the most critical issue for automotive vendors and parts manufacturers. In an effort to develop better and effective brake-by-wire system, this paper presents EMB system by using the low speed electric vehicle, which is not required large braking force, with motor controller. In addition, we design performance evaluation system of EMB with 1/4 low speed electric vehicle model and suggested EMB is evaluated through the performance evaluation system.

• Journal of the Korea Safety Management & Science
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• v.10 no.1
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• pp.83-90
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• 2008

Development of human-system interfaces (HSI) supporting the interaction between human and automation-based systems, particularly safety-critical sociotechnial systems, entails a wide range of design and evaluation problems. To help HSI designers deal with these problems, many methodologies from traditional human-computer interaction, software engineering, and systems engineering have been applied; however, they have been proved inadequate to develop cognitively well engineered HSI. This paper takes a viewpoint that HSI development is itself a cognitive process consisting of various decision making and problem solving activities and then proposes a design requirements-driven process for developing HSI. High-level design problems and their corresponding design requirements for visual information display are explained to clarify the concept of design requirements. Lastly, conceptual design of software system to support the requirements-driven process and designers' knowledge management is described.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.186-188
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• 2009

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. This paper discusses the safety strategies employed in the railway communications and proposes a security mechanism for Korean railway communication system.

• International Journal of Contents
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• v.8 no.4
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• pp.1-6
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• 2012

Mutual Exclusion is one of the most studied topics in distributed systems where processes communicate by asynchronous message passing. It is often necessary for multiple processes at different sites to access a shared resource or data called a critical section (CS) in distributed systems. A number of algorithms have been proposed to solve the mutual exclusion problem in distributed systems. In this paper, we propose the new algorithm which is modified from Garg's algorithm[1] thus works properly in a fault-tolerant system. In our algorithm, after electing the token generator, the elected process generates a new token based on the information of the myreqlist which is kept by every process and the reqdone which is received during election. Consequently, proposed algorithm tolerates any number of process failures and also does even when only one process is alive.

• Journal of Aerospace System Engineering
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• v.7 no.4
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• pp.27-35
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• 2013

Identifying the stability of rotor systems is prerequisite for clear determination of the parameter identification and safety, through which operating conditions may be rationally ascertained. For this purpose, the complex modal analysis of periodically time-varying system has been introduced by transforming the relation between periodic eigen-vectors and the corresponding adjoint vectors into the latent value problem. Stability investigation associated with modal features for rotor systems is performed using numerical simulation based upon the analysis model.

• Journal of KIISE:Software and Applications
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• v.30 no.5_6
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• pp.587-597
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• 2003

The C language is widely adopted for safety-critical systems. However, it is known that the C language is an unsuitable choice for safety-critical system since the C language includes several bad language features such as heavy use of pointers. The aim of this work is to define safe subset of the C language and translate the subset into the SPARK Ada so that we can verify the program's safety using SPARK analysis tools. SPARK is a safe subset of Ada and has been successfully applied to high integrity system development. The C program translated into SPARK has the same integrity level as SPARK, and the program correctness can be verified by using Examiner which is a SPARK analysis tool. An elevator controller case study is presented and is used to demonstrate the potential use of our approach to implement a realistic system. We also developed a translator that automatically translates C code into SPARK in accordance with the translation rules.

• Journal of the Korea Safety Management & Science
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• v.16 no.4
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• pp.343-349
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• 2014

Many systems using RFID/USN were and are being developed. Some systems are used in practice and some are not. Generally, the main reasons not being used are: The prices of chips are too high considering the effects. The application domain is not appropriate for RFID/USN. So, various skills for higher sensing precision have been introduced like using multiple sensors and avoiding metals which deter sensings seriously. Now, it is time to evaluate systems which were developed using RFID/USN technology. However, no systematic approach has been made for the evaluation. In this paper, a framework using BSC is introduced for the evaluation of systems using RFID/USN. In this framework, some Critical Success Factors(CSF) are derived and some Key Performance Indices(KPI) are developed for each CSF.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.11
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• pp.1130-1137
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• 2006

Relaxed Static Stability(RSS) concept has been applied to improve aerodynamic performance of modern version supersonic jet fighter aircraft. Therefore, the flight control systems are necessary to stabilizes the unstable aircraft and provides adequate handling qualities. The initial production flight control system are verified by flight test and it's always an elements of danger because of flight-critical nature of control law function and design error due to model base design method. These critical issues impact to flight safety, and it could be lead to a loss of aircraft and pilot's life. Therefore, development of an easily modifiable RFCS(Research Flight Control System) capable of reverting to a PFCS(Primary Flight Control System) of reliable control law must be developed to guarantee the flight safety. This paper addresses the concept of SSWM(Software Switching Mechanism) using the fader logic such as TFS(Transient Free Switch) based on T-50 flight control law. The result of the analysis based on non-real time simulation in-house software using SSWM reveals that the flight control system are switching between two computers without any problem.