• 한국항공우주학회지
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• 제42권5호
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• pp.398-405
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• 2014

내장형 소프트웨어 기술이 항공 및 방위산업과 같은 안전-필수 시스템에 적용됨에 따라 보다 높은 소프트웨어의 신뢰성이 요구되고 있다. 그 중에서 소프트웨어의 무결성은 주로 정적 분석 도구를 이용해 검증이 이뤄지고 있으며 최근에 개발된 정적 분석 도구는 수학적인 분석 방법을 통해 코드의 무결성을 평가하고 있다. 본 연구에서는 정형 검증 도구인 Polyspace를 이용해 자동코드의 결함을 검출하고, 코딩규칙의 준수 여부를 검증하였다. 검증된 결과를 바탕으로 결함을 가진 제어법칙 모델을 수정하여 코드 생성 이전의 원천적인 결함을 제거 가능함을 확인하였고 FBW 헬리콥터 제어법칙 자동생성코드의 무결성을 확보 할 수 있었다.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2002년도 가을 학술발표논문집 Vol.29 No.2 (2)
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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.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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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.

• 한국철도학회논문집
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• 제8권3호
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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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• 제5권2호
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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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• 제51권3호
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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

• 한국산학기술학회논문지
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• 제11권11호
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• pp.4460-4467
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• 2010

최근 컴퓨터시스템으로 전환되고 있는 철도시스템에서 소프트웨어에의 의존성이 급격히 증가함에 따라 임베디드화된 철도시스템 소프트웨어 신뢰성과 안전성의 검증이 중요한 문제로 대두되기 시작했다. 이에 따라 철도 소프트웨어 관련 국제표준에서도 각종 소프트웨어 테스트 및 검증활동을 요구하고 있으며, 이에 대응하여 본 논문에서는 철도시스템 소프트웨어 테스트 커버리지 자동화 도구 및 기준 분석과 개발 결과에 대해 제시하고 있다. 본 논문에서는 철도시스템 소프트웨어 안전성 검증을 위한 정량적인 항목으로 매우 중요한 테스트 커버리지를 자동으로 측정할 수 있는 제어흐름 분석도구를 개발하였으며, 본 도구의 결과를 실제 철도 산업 현장에서 활용하기 위해 타분야 제시기준 등을 분석하여 철도 소프트웨어 안전무결성레벨(SWSIL)에 따른 판단 기준을 제시하였다. 개발한 도구는 기존 해외 도구에 비해서 여러 테스트 커버리지를 효과적으로 측정할 수 있는 강점이 있으며, 실제 철도 현장에서 활용성이 높아 철도 소프트웨어의 개발 및 테스트 기술 발전을 기대할 수 있다.

• Journal of Information Processing Systems
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• 제8권2호
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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.

• 한국가스학회지
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• 제5권4호
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• pp.56-61
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• 2001

최근 여러 산업설비에서 주목받고 있는 RBI 소프트웨어는 개발한 회사에 따라 그 분석 수준, 적용분야, 반영하는 손상기구 등이 다양하다. 본 논문에서는 국내 여러 개의 기관이 공동으로 참여한 다자간 공동연구과제인, 해외 RBI 소프트웨어의 기능에 대한 조사연구에 대해 소개하였으며 연구 내용의 일부를 사례로서 보여주었다. 이 연구에서는 RBI 소프트웨어를 개발한 국외 기관별로 수집된 자료와 데모 프로그램을 동해서 기존 RBI 진단시스템의 장단점을 비교$\cdot$분석하였으며, 향후 RBI 소프트웨어를 개발하는 경우 필요한 최적기능에 대해 연구하였다.

• Nuclear Engineering and Technology
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• 제45권4호
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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.