• Nuclear Engineering and Technology
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• v.27 no.3
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• pp.385-392
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• 1995

A software engineering process has been developed for the design of safety critical software for Wolsong 2/3/4 project to satisfy the requirement of the regulatory body. Among the process, this paper described the detail process of validation testing peformed to ensure that the software with its hardware, developed by the design group, satisfies the requirements of the functional specification prepared by the independent functional group. To perform the test, test facility and test software ore developed and actual safety system computer was connected. Three kinds of test cases, i.e., functional test performance test and self-check test were programmed and run to verify each functional specifications. Test failures ore fedback to the design group to revise the software and test result were analyzed and documented in the report to submit to the regulatory body. The test methodology and procedure were very efficient and satisfactory to perform the systematic and automatic test. The test results were also acceptable and successful to verify the software acts as specified in the program functional specification. This methodology can be applied to the validation of other safety-critical software.

• Journal of the Korea Safety Management & Science
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• v.17 no.1
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• pp.93-101
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• 2015

The demand from customers on better products and systems seems to be ever increasing. To meet the demand, the systems are becoming more and more complicated in terms of both scale and functionality, thereby requiring enormous effort in the development. One bright spot of this trend is that such effort has been the driving forces of the remarkable advancement in modern systems development. On the other hand, safety issues appear to be critical in many large-scale systems such as transportation and weapon systems including high-speed trains, airplanes, ships, missiles/rockets launchers, and so on. Such systems turn out to be prone to a variety of faults and thus the resultant failure can cause disastrous accidents. For the reason, they can be referred to as safety-critical systems. The systems failure can be attributed to either random or systemic factors (or sometimes both). The objective of this paper is on how to reduce potential systemic failure in safety critical systems. To do so, a proper system design is pursued to minimize the risk of systemic failure. A focus is placed on the fact that complex systems have a lot of complicated interfaces among the system elements. To effectively handle the sources of hazards at the complicated interfaces and resultant failure, a method is developed by utilizing a design structure matrix. As a case study, the developed method is applied in the design of train control systems.

• Nuclear Engineering and Technology
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• v.38 no.3
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• pp.259-276
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• 2006

As the use of digital systems becomes more prevalent, adequate techniques for software specification and analysis have become increasingly important in nuclear power plant (NPP) safety-critical systems. Additionally, the importance of software verification and validation (V&V) based on adequate specification has received greater emphasis in view of improving software quality. For thorough V&V of safety-critical systems, V&V should be performed throughout the software lifecycle. However, systematic V&V is difficult as it involves many manual-oriented tasks. Tool support is needed in order to more conveniently perform software V&V. In response, we developed four kinds of computer aided software engineering (CASE) tools to support system specification for a formal-based analysis according to the software lifecycle. In this work, we achieved optimized integration of each tool. The toolset, NuSEE, is an integrated environment for software specification and V&V for PLC based safety-critical systems. In accordance with the software lifecycle, NuSEE consists of NuSISRT for the concept phase, NuSRS for the requirements phase, NuSDS for the design phase and NuSCM for configuration management. It is believed that after further development our integrated environment will be a unique and promising software specification and analysis toolset that will support the entire software lifecycle for the development of PLC based NPP safety-critical systems.

• 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 Advanced Navigation Technology
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• v.21 no.2
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• pp.155-162
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• 2017

In recent years, aviation-related safety-critical systems have been developed in Korea, but these products have not satisfied the specified requirements and thus have not been commercialized or commercialized. Due to increasing complexity of the modern aviation system, traditional verification and validation techniques are not sufficient to identify and reduce latent risks in the system. To overcome this shortcoming, a new method which is called 'Independent verification and validation (IV&V)' is suggested. However, academic researches on the effectiveness of this independent verification and validation have not been conducted domestically, and it is performed very rarely even overseas. Therefore, in this paper, we investigated the application of independent verification and validation of the safety-critical aviation systems performed by advanced aviation organizations, and analyzed various positive effects on projects. As a result of the analysis, IV&V shows that early error detection rate is increased, potential risk is mitigated early, and the complex reworking probability, which appears later in the development life cycle, is reduced, greatly preventing the development schedule and costs from increasing.

• 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.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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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.

• Journal of the Korean Society of Systems Engineering
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• v.14 no.2
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• pp.49-57
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• 2018

The main objective of this paper is come up with methodology approach for FPGA-based system in verification and validation lifecycle regarding software reliability using system engineering approach. The steps of both reverse engineering and re-engineering are carried out to implement an FPGA-based of safety critical system in Nuclear Power Plant. The reverse engineering methodology is applied to elicit the requirements of the system as well as gain understanding of the current life cycle and V&V activities of FPGA based-system. The re-engineering method is carried out to get a new methodology approach of software reliability, particularly Software Reliability Growth Model. For measure the software reliability of a given FPGA-based system, the following steps are executed as; requirements definition and measurement, evaluation of candidate reliability model, and the validation of the selected system. As conclusion, a new methodology approach for software reliability measurement using software reliability growth model is developed.

• International conference on construction engineering and project management
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• 2007.03a
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• pp.759-768
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• 2007

Construction is one of the most hazardous industries due to its unique nature. Recent occurrences of highly publicised and criticized construction site accidents have highlighted the immediate need for the construction industry to address safety hazards. Safety used to be addressed as an isolated issue in the past, but the problem of safety is an emergent property of a system. In general, it seems that both industrial practitioners and government officials have tended to address safety by focusing on technical aspects and looking for immediate causes of accidents after they have taken place. The objective of this paper is to examine issues and critical factors that affect the safety standards from a holistic point of view. The job of making worksites safe should not just fall squarely on the contractors but should be shared by all parties in the value chain of construction activities.

• Journal of the Korea Safety Management & Science
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• v.15 no.4
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• pp.37-47
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• 2013

Due to the evolution of war fields to the net-centric one, weapon systems have become very complex in terms of both mission capability and implementation scales. In particular, the net-centric war field is characterized by a set of interconnected and independently operable weapon systems. As such, the individual weapon systems are required to meet the interoperability and thus, assuring it has been becoming more crucial even in the early stage of development. Furthermore, the ever-growing complexity of the weapon systems has attracted a great deal of attention on the safety issues in the operation and development of weapon systems. The objective of the study is on how to assure the interoperability for safety-critical weapon systems while maintaining system complexity. To do so, the approach taken in the paper is to consider the interoperability from the early stage of the development. Specifically, the required functions to satisfy the interoperability are developed first. The functions are then analyzed in order to link the safety requirements to the reliability evaluation, which results in the study of quantifying the effects of the safety requirements on the system as a whole. As a result, we have developed a methodology and procedure on how to assure interoperability while applying the safety requirements in the weapon systems development.