• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.153-158
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• 1997

This paper describes a formal safety analysis technique which is demonstrated by performing empirical formal safety analysis with the case study of beamline hutch door Interlock system that is developed by using PLC(Programmable Logic Controller) systems at the Pohang Accelerator Laboratory. In order to perform formal safety analysis, we have built the Z formal specifications representation from user requirement written in ambiguous natural language and target PLC ladder logic, respectively. We have also studied the effective method to express typical PLC timer component by using specific Z formal notation which is supported by temporal history. We present a formal proof technique specifying and verifying that the hazardous states are not introduced into ladder logic in the PLC-based safety critical system.

• Journal of the Korea Safety Management & Science
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• v.17 no.3
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• pp.195-204
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• 2015

The live fire test has been playing a critical role in evaluating the goals-to-meet of the weapon systems which utilize the power of explosives. As such, the successful development of the test systems therein is quite important. The test systems development covers that of ranges and facilities including system-level key components such as mission control, instrumentation or observation, safety control, electric power, launch pad, and so on. In addition, proper operational guidelines are needed with well-trained test and operation personnel. The emerging weapon systems to be deployed in future battle field would thus have to be more precise and dynamic, smarter, thereby requiring more elaboration. Furthermore, the safety consideration is becoming more serious due to the ever-increasing power of explosives. In such a situation, development of live fire test systems seems to be challenging. The objective of the paper is on how to incorporate the safety and other requirements in the development. To achieve the goal, an architectural approach is adopted by utilizing both the system components relationship and safety requirement when advanced instrumentation technology needs to be developed and deteriorated components of the range are replaced. As an evaluation method, it is studied how the level of maturity of the test systems development can be assessed particularly with the safety requirement considered. Based on the concepts of both systems engineering and SoS (System-of-Systems) engineering process, an enhanced model for the system readiness level is proposed by incorporating safety. The maturity model proposed would be helpful in assessing the maturity of safety-critical systems development whereas the costing model would provide a guide on how the reasonable test resource allocation plan can be made, which is based on the live fire test scenario of future complex weapon systems such as SoS.

• IEMEK Journal of Embedded Systems and Applications
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• v.16 no.6
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• pp.267-276
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• 2021

The automotive industry and academic research have been continuously conducting research on standardization such as AUTOSAR (AUTomotive Open System ARchitecture) and ISO26262 to solve problems such as safety and efficiency caused by the complexity of electric/electronic architecture of automotive. AUTOSAR is an automotive standard software platform that has a layered structure independent of MCU (Micro Controller Unit) hardware, and improves product reliability through software modularity and reusability. And, ISO26262, an international standard for automotive functional safety and suggests a method to minimize errors in automotive ECU (Electronic Control Unit)s by defining the development process and results for the entire life cycle of automotive electrical/electronic systems. These design methods are variously applied in representative automotive safety-critical systems. However, since the functional and safety requirements are different according to the characteristics of the safety-critical system, it is essential to research the AUTOSAR functional safety design method specialized for each application domain. In this paper, a software functional safety mechanism design method using AUTOSAR is proposed, and a new failure management framework is proposed to ensure the high reliability of the product. The AUTOSAR functional safety mechanism consists of memory partitioning protection, timing monitoring protection, and end-to-end protection. The fault management framework is composed of several safety SWCs to maintain the minimum function and performance even if a fault occurs during the operation of a safety-critical system. Finally, the proposed method is applied to the Shift-by-Wire system design to prove the validity of the proposed method.

• Journal of Korean Critical Care Nursing
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• v.6 no.1
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• pp.44-56
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• 2013

Purpose: The purpose of this study was to investigate emergency room nurses' recognition of patient safety culture and their performance of safety management activity. Methods: Data were collected from July 1 to August 31, 2012 on 292 emergency room nurses working at 25 general hospitals located in B city in G province. The Hospital Survey on Patient Safety Culture was used to measure patient safety culture, and an 82-item questionnaire was developed to measure safety management activity. Results: the performance of safety management activity were significantly associated with the total career years, whether the nurses had undergone safety training, and whether the nurses has been working in the regional emergency care facility. Of 6 subcategories of the patient safety culture, the perception of a directly commanding senior/manager, frequency of accident reports, and hospital environment were associated with the performance of safety management activity. Conclusion: For improving performance of safety management activity among emergency room nurses, it is necessary to develop an educational program of safety management activity by their level of performance.

• International Journal of Quality Innovation
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• v.9 no.1
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• pp.134-152
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• 2008

Almost every country around the world has been focusing on food safety in intense and multifaceted ways. The use of Hazard Analysis Critical Control Points (HACCP) is widely accepted as a food safety management system. This paper investigates the success factors of HACCP practices with reference to the domains of food production, processing and delivery. A literature review of food safety and management articles was conducted. Using the keywords search, the online Emerald Database was used and a total of 102 journal articles were identified between 1994 and 2007. The study examined a list of 20 success factors. Results show that 'food regulations,' 'role of the industry,' 'government policies and interventions,' 'training on food safety and hygiene,' and 'food contamination and/or poisoning' share the spotlight as being the most critical factors for HACCP practices in organisations. Future research could investigate a holistic paradigm that incorporates the success factors and aligns HACCP measures for attaining safety performance goals.

• Journal of the Korean Society for Railway
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• v.20 no.1
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• pp.55-63
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• 2017

Railway interlocking systems which are safety-critical systems are rapidly changed from relay-based systems to computer-based systems which have high flexible. Computer-based interlocking systems (CBI) are consisted of hardware and software in which system safeties arise one of important problems. The interlocking software of the CBI influences directly to the system safeties. "z" notation is one of formal methods have been used for system software specification to secure system safety. In this paper, the specification of interlocking logics for CBI systems is realized using "z" notation and verifies it with Z/EVES.

• Structural Engineering and Mechanics
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• v.49 no.3
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• pp.311-327
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• 2014

The safety relating to leakage of water and pitch instability of ship chambers of the full balanced hoist vertical shiplifts has been the focus of adoption of the type of vertical shiplifts. This paper aims to remove the doubts through theoretical and engineering researches. The leakage and pitch stability of ship chambers of full balanced hoist vertical ship lifts are investigated on the basis of theoretical analysis and exploration of engineering measures. Regarding the issue of leakage of ship chambers, a mathematical model on leaking process is built and corresponding formula and coping measures are obtained which can be applied in control program of ship lifts by linking with monitoring. The concept of safety grade is put forward to seek the best technical and economic index and the corresponding technical measures are for different grades of ship lift is suggested. For the issue of pitch instability, a methodology of combining theoretical deduction and summary of achievements of design and operation of the type of the full balanced hoist shiplifts is adopted, and the formula for design about pitch stability of ship chambers is derived.

• Nuclear Engineering and Technology
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• v.52 no.7
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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.

• Proceedings of the KSR Conference
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• 2007.11a
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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.

• Journal of the Korea Safety Management & Science
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• v.10 no.4
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• pp.47-56
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• 2008

This study suggest a way to improve duty process of KTX(Korea Train Express) high-speed train driver. A new operating system which based on safety was introduced to operate high-speed train which travel above 300km/h on the high-speed railroad but below 200km/h on the general railroad. There were some studies on the operation of high-speed train which travel on the high-speed railroad and on the general railroad with safety. However they overlooked the elements of human errors. The duty-load of KTX train driver's 14 basic operation processes was measured using NASA-TLX and found four processes with high duty-load. In this paper, critical tasks of the high duty-load processes are determined using a questionnaire. Some suggestions which include the improvement of facilities, operating system and operating skill are proposed to lighten duty-load of the critical tasks. The validity of the proposed new task processes is demonstrated by making question to KTX train driver. To use this results cost-benefit analysis, hazards analysis etc. should be performed additionally.