• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.2044-2049
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• 2009

Recent advances in computer technology have brought more dependence on software to railway signaling systems. Hence, the safety assurance of the vital software running on the railway signaling system is very critical task and yet, not many works have been done. While much efforts have been reported to improve electronic hardware's safety, not so much systematic approaches to evaluate software's safety. In this paper, we suggested an automated analysis tool for S/W change impact in railway signaling system, and presented its result of implementation. The analysis items in the implemented tool had referred to the international standards in relation to the software for railway signaling system, such as IEC 61508 and IEC 62279. In these international standards, 'change impact analysis' for railway signaling system S/W has to be required mandatorily. The proposed tool can be utilized at the assessment stage and also the software development stage.

• 한국의료질향상학회지
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• 제23권1호
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• pp.11-23
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• 2017

Root Cause Analysis (RCA) has been widely used as a structured approach to investigate patient safety incidents. RCA helps identify what, how, and why something happened, therefore preventing recurrence of incidents. Since many quality tools can be used during RCA, various formats of RCA exist. If RCAs are performed incorrectly or incompletely, they are likely to produce unusable results. To address this issue, RCA software has been developed. The use of RCA software in investigating patient safety incidents may offer several advantages, such as potential reduction in learning time, shortening of the analytic process, facilitation of collection, analysis, and presentation of data and production of meaningful RCA reports. We introduced six healthcare RCA software and compared characteristics. Results from this study will enable the RCA team to choose proper RCA software.

• 설비공학논문집
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• 제29권10호
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• pp.538-550
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• 2017

In a PWR (Pressurized Water Reactor), the appropriate heat removal from the surface of fuel rod bundle is important for ensuring thermal margins and safety. Although many CFD (Computational Fluid Dynamics) software have been used to predict complex flows inside fuel assemblies with mixing vanes, there is no domestic regulatory guideline for the comprehensive evaluation of CFD software. Therefore, from the nuclear regulatory perspective, it is necessary to perform the systematic assessment and prepare the domestic regulatory guideline for checking whether valid CFD software is used for nuclear safety problems. In this study, to provide systematic evaluation and guidance on the applicability of CFD software to the domestic nuclear safety area, the results of the sensitivity analysis for the effect of the discretization scheme accuracy for the convection terms and turbulence models, which are main factors that contribute to the uncertainty in the calculation of the nuclear safety problems, on the prediction performance for the turbulent flow distribution inside the fuel assembly with split-type mixing vanes were explained.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.638-645
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• 2007

Computers are increasingly being introduced into safety and reliability critical systems. The safe and reliable operation of these systems cannot be taken for granted. Malfunctions of these systems can have potentially catastrophic consequences and they have already been involved in serious accidents. Software fault prevention, fault tolerance, fault removal and fault forecasting are the techniques to be used, implemented and verified for embedded software in critical systems as the contributors to safety and reliability of the software. To use them when developing a software product, a relationship must be established between them and the development processes, the methods and techniques to be used to develop software, as well as with the different product architectures. Railroad signaling system software is a safety-critical embedded software with realtime and high reliability requirements. The primary purpose of the safety management is to prevent the loss of lives or physical damages arising from potential hazards in the railroad signaling system. This study provides a systematic approach to analysis of potential hazards for their management during the system life cycle to assure the identification and definition of the most appropriate hazards.

• Nuclear Engineering and Technology
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• 제27권1호
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• pp.84-95
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• 1995

Application of computer software to safety-critical systems is on the increase. To be successful, the software must be designed and constructed to meet the functional and performance requirements of the system. For safety reason, the software must be demonstrated not only to meet these requirements, but also to operate safely as a component within the system. For longer-term cost consideration, the software must be designed and structured to ease future maintenance and modifications. This paper present a software engineering process for the production of safety-critical software for a nuclear power plant The presentation is expository in nature of a viable high quality safety-critical software development. It is based on the ideas of a rational design process and on the experience of the adaptation of such process in the production of the safety-critical software for the Shutdown System Number Two of Wolsong 2, 3 & 4 nuclear power generation plants. This process is significantly different from a conventional process in terms of rigorous software development phases and software design techniques. The process covers documentation, design, verification and testing using mathematically precise notations and highly reviewable tabular format to specify software requirements and software design. These specifications allow rigorous, stepwise verification of software design against software requirements, and code against software design using static analysis. The software engineering process described in this paper applies the principle of information-hiding decomposition in software design using a modular design technique so that when a change is' required or an error is detected, the affected scope can be readily and confidently located. It also facilitates a sense of high degree of confidence in the ‘correctness’ of the software production, and provides a relatively simple and straightforward code implementation effort.

• 디지털콘텐츠학회 논문지
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• 제18권2호
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• pp.393-401
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• 2017

각 산업분야에 사용되는 시스템의 소프트웨어 비중이 늘어남에 따라 소프트웨어 안전성과 관련된 사고가 증가하고 있다. 철도, 항공, 의료 등의 주요 산업분야에서는 이를 해결하기 위해 IEC 61508 기반의 안전표준을 작성하여 따르는 것을 권고하고 있다. 항해 장비분야에는 안전표준이 마련되어 있지 않아 기능안전에 대한 확인을 위해 적절한 가이드가 필요하다. 본 논문에서는 정보통신산업진흥원의 기능안전성 공통 개발 가이드를 참고하여 항해 장비의 소프트웨어 기능안전성 확보를 위한 위험분석 단계의 절차와 산출물을 정의하였다. 선박에 탑재하여 수심을 측정하는 음향측심기를 대상으로 사례 연구를 하였다.

• Nuclear Engineering and Technology
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• 제46권1호
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• pp.55-62
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• 2014

A method for estimating software reliability for nuclear safety software is proposed in this paper. This method is based on the software reliability growth model (SRGM), where the behavior of software failure is assumed to follow a non-homogeneous Poisson process. Two types of modeling schemes based on a particular underlying method are proposed in order to more precisely estimate and predict the number of software defects based on very rare software failure data. The Bayesian statistical inference is employed to estimate the model parameters by incorporating software test cases as a covariate into the model. It was identified that these models are capable of reasonably estimating the remaining number of software defects which directly affects the reactor trip functions. The software reliability might be estimated from these modeling equations, and one approach of obtaining software reliability value is proposed in this paper.

• 한국항행학회논문지
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• 제15권5호
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• pp.687-695
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• 2011

지식 정보 기술력 중심의 지식기반 경제 원천인 소프트웨어로 인한 결함은 항공기의 운용에 핵심 역할을 수행하는 엔진에 영향을 준다. 따라서 소프트웨어의 안전성분석을 통해 항공안전을 강화하여 결함으로부터의 위험을 최소화해야 한다. 본 논문에서는 항공기 결함과 소프트웨어 안전성 법 제도를 살펴보고 항공안전을 강화하기 위한 법 제도 개선 및 제정 방안을 제안한다. 안전성분석과 관련된 용어 정립, 안전성이 포함된 품질인증 기준, 안전성분석서를 첨부해야 하는 품질인증 신청, 평가 및 인증기관 세부지침 개정 등의 항목으로 기존 법 제도를 개선해야 한다. 또한, 소프트웨어 평가 및 인증 의무화, 소프트웨어 생명주기에 다른 지속적 평가, 표준화된 개발방법론 도입 의무화, 고급인력 양성 제도 강화 등의 항목으로 신규 법 제도를 제정해야한다. 소프트웨어 안전성과 관련된 기존 법 제도를 개선하고 신규 법 제도를 제정하여 소프트웨어의 품질 향상과 강화된 항공안전을 기대할 수 있다.

• 대한안전경영과학회지
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• 제3권3호
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• pp.213-220
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• 2001

This paper presents the interrelationship between software quality character and engineering attributes. The software quality characteristics and subcharacteristics are excerpted from IS0/IEC 9126 standards, and the engineering attributes are from Deutsch and Willis〔4〕. Based on the previous studies a subjective judgement, trisected interrelationship(strong, medium, weak) bet these two groups are derived. The results are summarized in a table, and can be used as a quick reference guide to the software quality engineering application such as quality evaluations for software products, selection of key engineering attributes for high-quality software production, and so forth.

• Nuclear Engineering and Technology
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• 제52권7호
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• pp.1462-1470
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• 2020

Reliability in safety-critical systems and equipment is of vital importance, so the probabilistic safety assessment (PSA) has been widely used for many years in the nuclear industry to address reliability in a quantitative manner. As many nuclear power plants (NPPs) become digitalized, evaluating the reliability of safety-critical software has become an emerging issue. Due to a lack of available methods, in many conventional PSA models only hardware reliability is addressed with the assumption that software reliability is perfect or very high compared to hardware reliability. This study focused on developing a new method of safety-critical software reliability quantification, derived from hardware-software integrated environment testing. Since the complexity of hardware and software interaction makes the possible number of test cases for exhaustive testing well beyond a practically achievable range, an importance-oriented testing method that assures the most efficient test coverage was developed. Application to the test of an actual NPP reactor protection system demonstrated the applicability of the developed method and provided insight into complex software-based system reliability.