• 정보과학회 논문지
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• 제44권9호
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• pp.893-907
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• 2017

안전 필수 시스템에서 소프트웨어 결함은 심각한 결과를 초래하므로, 개발의 첫 단계인 요구사항 명세부터 안전성을 고려해야한다. 자연어로 작성된 요구사항은 여러 이해관계자들에게서 도출되어 모호함과 부정확성에 의한 결함을 갖고 있어도 검출하기 어렵다. 이러한 문제를 해결하기 위해 표준문안과 GSN 모델을 이용한 요구사항 명세방법을 제안한다. 표준문안은 선 정의된 서식에 맞춰 요구사항을 작성하는 준-정형 언어로, 표준문안에 맞춰 요구사항을 작성하면 표현의 일관성을 갖기 때문에 이해관계자들이 요구사항이 의미하는 바에 대한 모호함을 방지하여 요구사항의 정확한 의미를 정의하는데 도움이 된다. GSN은 시스템이 안전하다는 것을 관련기관에 증명하기 위한 Safety Case 작성에서 적합성을 인정받고 있는 표기법으로 기능목표, Safety Evidence 등을 표현한다. 본 연구에서는 안전 필수 시스템의 요구사항을 명세하기에 적합하도록 설계된 표준문안과 GSN 모델을 이용하여 요구사항 명세단계에서부터 결함을 쉽게 식별하고, Safety Evidence와의 연결을 통해 안전적합성을 증명할 수 있다. 또한 이 과정에서 발견된 요구사항의 결함을 수정하여 안전성 있는 소프트웨어를 개발할 수 있다.

• 한국경영정보학회:학술대회논문집
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• 한국경영정보학회 2007년도 International Conference
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• pp.184-189
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• 2007

Concerns about food safety continue to rise and under this situation, governments of some countries have reinforced their regulations more strictly for food safety. In order to prevent food safety incidents or, at least to minimize the impact, the preparedness is very important. As a consequence of this, traceability system has become an essential tool for food safety. Recently, it requires more prevention-based food safety control system. One of the most generally used systems for food safety control is Hazard Analysis and Critical Control Point (HACCP). Both traceability and HACCP systems can be integrated through Electronic Product Code (EPC) Sensor Network technologies which have four value propositions. In this paper, we will introduce the concept of product and process traceability system (P2TS) through the integration of three systems to improve food safety management. The final aim is to find out the added values of the P2TS.

• Industrial Engineering and Management Systems
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• 제14권4호
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• pp.379-391
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• 2015

Several risk assessment techniques have been presented and investigated in previous research, focusing mainly on the failure mode and effect analysis (FMEA). FMEA can be employed to determine where failures can occur within industrial systems and to assess the impact of such failures. This research proposes a novel methodology for hazard analysis and risk assessments that integrates FMEA with the bow-tie model. The proposed method has been applied and evaluated in a real industrial process, illustrating the effectiveness of the proposed method. Specifically, the bowtie diagram of the critical equipment in the adopted plant in the case study was built. Safety critical barriers are identified and each of these is assigned to industrial process with an individual responsible. The detection rating to the failure mode and the values of risk priority number (RPN) are calculated. The analysis shows the high values of RPN are 500 and 490 in this process. A global corrective actions are suggested to improve the RPN measure. Further managerial insights have been provided.

• 시스템엔지니어링학술지
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• 제14권2호
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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.

• 시스템엔지니어링학술지
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• 제15권2호
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• pp.108-115
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• 2019

The activities of managing and controlling the configuration of a system component over its life cycle are critical tasks in developing a high safety system as well as general system development. These configuration management activities should be defined through the management plan at the beginning of the life cycle, and should be performed continuously and systematically until the end of the project after the system or product development is completed. In this study, the configuration management process applied in the development of high safety railway signaling system was introduced and an efficient application proposals of it was proposed. In particular, configuration management through the establishment of a configuration management system based on computer tools is one of the important activities of maintaining the configuration integrity of the system or product.

• 전력전자학회논문지
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• 제24권4호
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• pp.244-258
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• 2019

The reliability of power electronic systems becomes increasingly important, as power electronic systems have gradually gained an essential status in a wide range of industrial applications. Accordingly, recent research has made an effort to improve the reliability of power electronic systems to comply with stringent constraints on safety, cost, and availability. The condition monitoring of power electronic components is one of the main topics in the research area of the reliability of power electronic systems. In this paper, condition-monitoring methods of reliability-critical components in power electronic systems are discussed to provide the current state of knowledge by organizing and evaluating current representative literature.

• 시스템엔지니어링학술지
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• 제16권2호
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• pp.16-26
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• 2020

Improving operator performance in complex and time-critical situations is critical to maintain plant safety and operability. These situations require quick detection, diagnosis, and mitigation actions to recover from the root cause of failure. One of the key challenges for operators in nuclear power plants is information management and following the control procedures and instructions. Nowadays Digital Twin technology can be used for analyzing and fast detection of failures and transient situations with the recommender system to provide the operator or maintenance engineer with recommended action to be carried out. Systems engineering approach (SE) is used in developing a digital twin for the CEDM system to support operator actions when there is a misalignment in the control element assembly group. Systems engineering is introduced for identifying the requirements, operational concept, and associated verification and validation steps required in the development process. The system developed by using a machine learning algorithm with a text mining technique to extract the required actions from limiting conditions for operations (LCO) or procedures that represent certain tasks.

• 한국멀티미디어학회논문지
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• 제17권2호
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• pp.170-179
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• 2014

요즘 고령화가 급속히 진행되고 있고 이에 따라 시니어들의 응급구난 시스템에 대한 관심이 높아지고 있다. 따라서 시니어들의 응급구난을 관리하는 U-Healthcare 시스템의 경우 시니어들의 안전과 직결되는 응급 처치 및 구난을 하는 시스템으로서 안전성이 매우 중요한 안전성 중심 시스템이다. 따라서 본 논문에서는 시니어들의 생명과 밀접한 응급구난 관리를 위한 U-Healthcare 시스템에 대하여 결함분석과 안전성평가를 수행하여 그 효과를 알 수 있었다. 최근에는 안전성 중심 시스템은 인간 오류에 적용하기 힘든 소프트웨어의 특성 때문에 어느 하나의 시스템을 평가하기 위한 방법으로 상호보완적인 역할을 할 수 있는 두 가지 이상의 방법을 결합하는 연구가 진행되고 있다. 따라서 본 논문에서는 결함 트리 분석(FTA)와 전후방 고장유형, 효과 및 치명도 분석(FMECA)의 통합에 의해서 결함 분석과 안전성평가를 수행하였다. 먼저 시스템의 기능별 결함 목록을 통하여 F-FMECA를 구하여 FTA를 구하였다. 그리고 FTA를 이용하여 B-FMECA에서 정규화 위험 우선순위 값인 NRPV를 구하였다. 정규화 위험 우선순위 값 NRPV에 따라 우선순위를 부여하여 FTA를 추가 수정하여 개선 전과 개선 후의 결과인 개선율을 통해 수치적으로 개선효과를 구할 수 있었다.

• Nuclear Engineering and Technology
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• 제52권12호
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• pp.2687-2698
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• 2020

Most of the machine learning-based intrusion detection tools developed for Industrial Control Systems (ICS) are trained on network packet captures, and they rely on monitoring network layer traffic alone for intrusion detection. This approach produces weak intrusion detection systems, as ICS cyber-attacks have a real and significant impact on the process variables. A limited number of researchers consider integrating process measurements. However, in complex systems, process variable changes could result from different combinations of abnormal occurrences. This paper examines recent advances in intrusion detection algorithms, their limitations, challenges and the status of their application in critical infrastructures. We also introduce the discussion on the similarities and conflicts observed in the development of machine learning tools and techniques for fault diagnosis and cybersecurity in the protection of complex systems and the need to establish a clear difference between them. As a case study, we discuss special characteristics in nuclear power control systems and the factors that constraint the direct integration of security algorithms. Moreover, we discuss data reliability issues and present references and direct URL to recent open-source data repositories to aid researchers in developing data-driven ICS intrusion detection systems.

• Nuclear Engineering and Technology
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• 제45권5호
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• pp.637-652
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• 2013

Instrumentation and control systems in nuclear power plants have been digitalized for the purpose of maintenance and precise operation. This digitalization, however, brings out issues related to cyber security. In the most recent past, international standard organizations, regulatory institutes, and research institutes have performed a number of studies addressing these systems cyber security.. In order to provide information helpful to the system designers in their application of cyber security for the systems, this paper presents methods and considerations to define attack vectors in a target system, to review and select the requirements in the Regulatory Guide 5.71, and to integrate the results to identify applicable technical security control requirements. In this study, attack vectors are analyzed through the vulnerability analyses and penetration tests with a simplified safety system, and the elements of critical digital assets acting as attack vectors are identified. Among the security control requirements listed in Appendices B and C to Regulatory Guide 5.71, those that should be implemented into the systems are selected and classified in groups of technical security control requirements using the results of the attack vector analysis. For the attack vector elements of critical digital assets, all the technical security control requirements are evaluated to determine whether they are applicable and effective, and considerations in this evaluation are also discussed. The technical security control requirements in three important categories of access control, monitoring and logging, and encryption are derived and grouped according to the elements of attack vectors as results for the sample safety system.