• Nuclear Engineering and Technology
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• v.33 no.6
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• pp.596-604
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• 2001

This paper quantitatively presents the effects of important factors of the probabilistic safety assessment (PSA) of safety-critical digital systems. The result which is quantified using fault tree analysis methodology shows that these factors remarkably affect the system safety. In this paper we list the factors which should be represented by the model for PSA. Based on the PSA experience, we select three important factors which are expected to dominate the system unavailability. They are the avoidance of common cause failure, the coverage of fault tolerant mechanisms and software failure probability. We Quantitatively demonstrate the effect of these three factors. The broader usage of digital equipment in nuclear power plants gives rise to the safety problems. Even though conventional PSA methods are immature for applying to microprocessor-based digital systems, practical needs force us to apply it because the result of PSA plays an important role in proving the safety of a designed system. We expect the analysis result to provide valuable feedback to the designers of digital safety- critical systems.

• Nuclear Engineering and Technology
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• v.41 no.4
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• pp.447-454
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• 2009

This paper is a technical review of the research and development results of the Korea Nuclear Instrumentation and Control System (KNICS) project and Nu-Tech 2012 program. In these projects man-machine interface system architecture, two digital platforms, and several control and protection systems were developed. One platform is a Programmable Logic Controller (PLC) for a digital safety system and another platform is a Distributed Control System (DCS) for a non-safety control system. With the safety-grade platform PLC, a reactor protection system, an engineered safety feature-component control system, and reactor core protection system were developed. A power control system was developed based on the DCS. A logic alarm cause tracking system was developed as a man-machine interface for APR1400. Also, Integrated Performance Validation Facility (IPVF) was developed for the evaluation of the function and performance of developed I&C systems. The safety-grade platform PLC and the digital safety system obtained approval for the topical report from the Korean regulatory body in February of 2009. A utility and vendor company will determine the suitability of the KNICS and Nu- Tech 2012 products to apply them to the planned nuclear power plants.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.987-992
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• 2007

Safety critical systems are those in which a failure can have serious and irreversible consequences. Nowadays digital technology has been rapidly applied to critical system such as railways, airplanes, nuclear power plants, vehicles. The main difference between analog system and digital system is that the software is the key component of the digital system. The digital system performs more varying and highly complex functions efficiently compared to the existing analog system because software can be flexibly designed and implemented. The flexible design make it difficult to predict the software failures. This paper reviews safety standard and criteria for safety critical system such as railway system and introduces the framework for the software lifecycle. The licensing procedure for the railway software is also reviewed.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1201-1202
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• 2007

Safety critical systems are those in which a failure can have serious and irreversible consequences. Nowadays digital technology has been rapidly applied to critical system such as railways, airplanes, nuclear power plants, vehicles. The main difference between analog system and digital system is that the software is the key component of the digital system. The digital system performs more varying and highly complex functions efficiently compared to the existing analog system because software can be flexibly designed and implemented. The flexible design make it difficult to predict the software failures. This paper reviews safety standard and criteria for safety critical system such as railway system and introduces the framework for the software lifecycle. The licensing procedure for the railway software is also reviewed.

• IE interfaces
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• v.23 no.1
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• pp.68-77
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• 2010

Digital reactor protection system which consists of many identical modules, is fault- tolerant to provide high safety. The modules themselves including DSP(digital signal processing) card are also fault-tolerant in nature. This paper assesses the safety for being-designed digital reactor protection system of 2-out-of-4 G structure with lockout. Some interesting design alternatives are compared. Fault tree analysis for assessing system safety is performed by Relex software. The selected reactor protection system fully satisfies EPRIURD stipulation of mean failure time of 50 years.

• Nuclear Engineering and Technology
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• v.41 no.6
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• pp.849-858
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• 2009

Risk caused by safety-critical instrumentation and control (I&C) systems considerably affects overall plant risk. As digitalization of safety-critical systems in nuclear power plants progresses, a risk model of a digitalized safety system is required and must be included in a plant safety model in order to assess this risk effect on the plant. Unique features of a digital system cause some challenges in risk modeling. This article aims at providing an overview of the issues related to the development of a static fault-tree-based risk model. We categorize the complicated issues of digital system probabilistic risk assessment (PRA) into four groups based on their characteristics: hardware module issues, software issues, system issues, and safety function issues. Quantification of the effect of these issues dominates the quality of a developed risk model. Recent research activities for addressing various issues, such as the modeling framework of a software-based system, the software failure probability and the fault coverage of a self monitoring mechanism, are discussed. Although these issues are interrelated and affect each other, the categorized and systematic approach suggested here will provide a proper insight for analyzing risk from a digital system.

• Journal of Auto-vehicle Safety Association
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• v.8 no.2
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• pp.17-23
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• 2016

Construction of our machine "Digital Tacho Graph" toghether with development and intergrated management system information is attached under Traffic Safety Law in article submission. This machine "Digital Tach Graph" has been mandated on a priority basis. The entire machine is constructed with specialised components to collect data that can retrive basic information. To obtain the components to perfect the information to optimize the device and system.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.201-203
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• 2007

Safety critical systems are those in which a failure can have serious and irreversible consequences. Nowadays digital technology has been rapidly applied to critical system such as railways, airplanes, nuclear power plants, vehicles. The main difference between analog system and digital system is that the software is the key component of the digital system. The digital system performs more varying and highly complex functions efficiently compared to the existing analog system because software can be flexibly designed and implemented. The flexible design make it difficult to predict the software failures. This paper reviews safety standard and criteria for safety critical system such as railway system and suggests software development methodology for more detail description.

• Journal of the Korean Society of Safety
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• v.37 no.5
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• pp.14-21
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• 2022

The purpose of this study was to apply the signal pattern recognition technique to the digital wireless fire-alarm system and to reduce unwanted fire alarms. In this study, the fire alarms of the K Institute, which operates the largest digital wireless fire-alarm system in Korea, were classified into normal operations and unwanted fire alarms, and these were analyzed and compared with actual fire signals. In addition, by designing a non-fire signal filter and applying it to the K Institute, we confirmed that the monthly unwanted fire alarm rate of all 5,713 detectors decreased sharply. In particular, the unwanted fire alarm rate for flame decreased from 1.09% to 0.11% and the unwanted fire alarm rate for smoke decreased from 0.65% to 0.035%.

• Convergence Security Journal
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• v.15 no.7
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• pp.97-102
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• 2015

Recently, each country should operates a integrated disaster safety management system in order to reduce the damage, such as the world-natural disasters. In particular, research on digital signage use has been mad e by a method for transmitting a disaster warning message. In this paper, we tried to examine the security requirements that are required by the disaster safety netwo rk by looking at the digital signage concept and disaster safety management system. Also, in order to be tra nsmitted to the safe digital signage terminal a common alarm message in the disaster safety services using d igital signage, we propose a protocol that uses a public key authentication mechanism. The proposed protocol is to be safely displayed a common alarm message to the appropriate area.