• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.5
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• pp.398-405
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• 2014

Recently the embedded software has been widely applied to the safety-critical systems in aviation and defense industries, therefore, the higher level of reliability, availability and fault tolerance has become a key factor for its implementation into the systems. The integrity of the software can be verified using the static analysis tools. And recent developed static analysis tool can evaluate code integrity through the mathematical analysis method. In this paper we detect the autocode error and violation of coding rules using the formal verification tool, Polyspace(R). And the fundamental errors on the flight control law model have been detected and corrected using the formal verification results. As a result of verification process, FBW helicopter control law autocode can ensure code integrity.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10d
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• pp.19-21
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• 2002

Writing requirements in formal notation for a safety-critical system can improve software quality and reduce the errors that may arise later on in the software development life cycle. In this paper, we propose a formal specification approach used to describe the nuclear control system. The approach is based on the existing AECL approach that was the only formal specification technique applied to nuclear control systems in the past. Although the approach is AECL-based, the complex descriptions of certain requirements have been reduced by using different specification techniques. We discuss the differences and how the proposed approach provides not only specification but also verification environment.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.363-370
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• 2008

The surveillance system for urban transit now adapt the newest IT technology. The Surveillance system analyzes the video information from various cameras intelligently and determines the critical status automatically. Other sensors, for example fire sensor and audio sensor are used in the surveillance system for increasing the correctness of surveillance. The surveillance system tries to increase the performance of surveillance by gathering lots of information for the current situation and analyzing them intelligently. IP-Based Integrated system needs the distributed computer system with location and functions. For correctly running this system, a distributed software is needed. In this paper, we study the distributed software for IP-based integrated surveillance system. The required functions, safety and extendability are suggested.

• Journal of the Korean Society for Railway
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• v.8 no.3
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• pp.253-259
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• 2005

This paper describes 3D Dimensional Measurement(EDM testing) and tensile testing results of carbody structure for crashed EMU(Electric Multiple Units). Tensile tests were performed on two different types of specimens in order to evaluate the strength changes before and after damages, obtained from plastic deformed area and nondeformed region of the crashed EMU. And Structural analysis of EMU was performed for the criteria of safety assessment. Structural analysis using commercial I-DEAS software provided important information on the stress distribution and load transfer mechanisms as well as the amount of damages during rolling stock crash. The testing results have been used to provide the critical information for the criteria of safety diagnosis.

• International Journal of Railway
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• v.5 no.2
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• pp.93-101
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• 2012

Owing to the lightening of railway vehicles and increased operation speeds, the reduction of running safety in the presence of crosswind is becoming an important problem. In particular, the running safety tends to decrease when vehicles run on curved track. When a crosswind acts on a vehicle negotiating a curve from the outer side, flange climbing can occur. In this study, a full-vehicle model was constructed using the multi-body simulation software SIMPACK, and a simulation of a bogie vehicle with two-axle trucks negotiating a curve was carried out to examine the running safety under the condition where a crosswind acts on the vehicle from the outer side of the curve. As a result, it was verified that the derailment coefficient of the first wheelset becomes large in the exit transition curve and the coefficient of the third wheelset does in the entrance transition curve, and this trend becomes pronounced at low operation speeds in the presence of a stronger crosswind. It was also shown that the critical derailment coefficients obtained by modified Nadal's formula considering the effect of attack angle become close to the actual derailment coefficients at the timing that flange climbing occurs.

• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.692-701
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• 2019

Recently, instrumentation and control (I&C) systems in nuclear power plants have undergone digitalization. Owing to the unique characteristics of digital I&C systems, the reliability analysis of digital systems has become an important element of probabilistic safety assessment (PSA). In a reliability analysis of digital systems, fault-tolerant techniques and their effectiveness must be considered. A fault injection experiment was performed on a safety-critical digital I&C system developed for nuclear power plants to evaluate the effectiveness of fault-tolerant techniques implemented in the target system. A software-implemented fault injection in which faults were injected into the memory area was used based on the assumption that all faults in the target system will be reflected in the faults in the memory. To reduce the number of required fault injection experiments, the memory assigned to the target software was analyzed. In addition, to observe the effect of the fault detection coverage of fault-tolerant techniques, a PSA model was developed. The analysis of the experimental result also can be used to identify weak points of fault-tolerant techniques for capability improvement of fault-tolerant techniques

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.11
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• pp.4460-4467
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• 2010

Recent advances in computer technology have brought more dependence on software to railway systems and changed to computer systems. Hence, the reliability and safety assurance of the vital software running on the embedded railway system is going to tend toward very critical task. Accordingly, various software test and validation activities are highly recommended in the international standards related railway software. In this paper, we presented an automated analysis tool and standard for software testing coverage in railway system, and presented its result of implementation. We developed the control flow analysis tool estimating test coverage as an important quantitative item for software safety verification in railway software. Also, we proposed judgement standards due to railway S/W Safety Integrity Level(SWSIL) based on analysis of standards in any other field for utilizing developed tool widely at real railway industrial sites. This tool has more advantage of effective measuring various test coverages than other countries, so we can expect railway S/W development and testing technology of real railway industrial sites in Korea.

• Journal of Information Processing Systems
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• v.8 no.2
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• pp.213-240
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• 2012

Safety critical systems, real time systems, and event-based systems have a complex set of events and their own interdependency, which makes them difficult to test ma Safety critic Safety critical systems, real time systems, and event-based systems have a complex set of events and their own interdependency, which makes them difficult to test manually. In order to cut down on costs, save time, and increase reliability, the model based testing approach is the best solution. Such an approach does not require applications or codes prior to generating test cases, so it leads to the early detection of faults, which helps in reducing the development time. Several model-based testing approaches have used different UML models but very few works have been reported to show the generation of test cases that use events. Test cases that use events are an apt choice for these types of systems. However, these works have considered events that happen at a user interface level in a system while other events that happen in a system are not considered. Such works have limited applications in testing the GUI of a system. In this paper, a novel model-based testing approach is presented using business events, state events, and control events that have been captured directly from requirement specifications. The proposed approach documents events in event templates and then builds an event-flow model and a fault model for a system. Test coverage criterion and an algorithm are designed using these models to generate event sequence based test scenarios and test cases. Unlike other event based approaches, our approach is able to detect the proposed faults in a system. A prototype tool is developed to automate and evaluate the applicability of the entire process. Results have shown that the proposed approach and supportive tool is able to successfully derive test scenarios and test cases from the requirement specifications of safety critical systems, real time systems, and event based systems.

• Journal of the Korean Institute of Gas
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• v.5 no.4 s.16
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• pp.56-61
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• 2001

Recently RBI softwares have received widespread interests from various industries. The available RBI softwares have variety of levels of analysis, fields of applications and damage mechanisms considered, which depend on the software developing institutes. In this paper results of a GSP(Group Sponsored Project) entitled 'Study on Surveying Functions of Foreign RBI Softwares' are summarized. A part of the study is explained in detail as a sample case for showing the contents of the project. Based on the demo softwares as well as the open documents and contents obtained in the web pages of the developer critical comparisons of the well-known RBI softwares were made. The required functions of the optimal RBI software is also discussed from the review results of this study.

• Nuclear Engineering and Technology
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• v.45 no.4
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• pp.477-488
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• 2013

The PLC (Programmable Logic Controller) has been widely used to implement real-time controllers in nuclear RPSs (Reactor Protection Systems). Increasing complexity and maintenance cost, however, are now demanding more powerful and cost-effective implementation such as FPGA (Field-Programmable Gate Array). Abandoning all experience and knowledge accumulated over the decades and starting an all-new development approach is too risky for such safety-critical systems. This paper proposes an RPS software development process with a platform change from PLC to FPGA, while retaining all outputs from the established development. This paper transforms FBD designs of the PLC-based software development into a behaviorally-equivalent Verilog program, which is a starting point of a typical FPGA-based hardware development. We expect that the proposed software development process can bridge the gap between two software developing approaches with different platforms, such as PLC and FPGA. This paper also demonstrates its effectiveness using an example of a prototype version of a real-world RPS in Korea.