• Journal of Computing Science and Engineering
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• v.10 no.3
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• pp.75-84
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• 2016

Medical cyber-physical systems (MCPS) integrate sensors, actuators, and software to improve patient safety and quality of healthcare. These systems introduce major challenges to safety analysis because the patient's physiology is complex, nonlinear, unobservable, and uncertain. To cope with the challenge that unidentified physiological parameters may exhibit short-term variances in certain clinical scenarios, we propose a novel run-time predictive safety monitoring technique that leverages a maximal model coupled with online training of a computational virtual subject (CVS) set. The proposed monitor predicts safety-critical events at run-time using only clinically available measurements. We apply the technique to a surgical glucose control case study. Evaluation on retrospective real clinical data shows that the algorithm achieves 96% sensitivity with a low average false alarm rate of 0.5 false alarm per surgery.

• Journal of KIISE:Software and Applications
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• v.35 no.12
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• pp.731-740
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• 2008

A railway control system is one of the typical safety-critical systems. It is required to use formal methods for the requirements specification and verification in order to develop the global-standard railway control systems based on the computer systems. In this paper, we develop a guideline for requirements specification using formal methods, and present a case study of the development of a computer-based railway control system through the application of the proposed guideline. We use the Statechart and the Z method for the formal requirements specifications and verify the consistency and completeness of the formal specifications of the requirements.

• Journal of Computing Science and Engineering
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• v.8 no.1
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• pp.34-42
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• 2014

Time-predictability of computing is critical for hard real-time and safety-critical systems. However, currently there is no metric available to quantitatively evaluate time-predictability, a feature crucial to the design of time-predictable processors. This paper first proposes the concept of architectural time-predictability, which separates the time variation due to hardware architectural/microarchitectural design from that due to software. We then propose the standard deviation of clock cycles per instruction (CPI), a new metric, to measure architectural time-predictability. Our experiments confirm that the standard deviation of CPI is an effective metric to evaluate and compare architectural time-predictability for different processors.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.136-136
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• 2017

By-products has been considered lately in Total Mixed Ration (TMR) as an alternative to livestock feed around the world. This is due to the high cost of using forage as feed, less expense in exploring by-products of agriculture origin and environmental concerns with their disposal. However, by-products usually contain contaminants and the production process requires fermentation using a storage and fermentation tank. Animal feed is the start point of the food safety chain in the 'farm-to-fork' model. This necessitated a study to model a protocol that will culminate to safe feed production. Hazard analysis and critical control points (HACCP), a systematic preventive approach to food safety from biological, chemical and physical hazards in production processes that can cause the finished product to be unsafe was explored. Implementation of this model provides a mechanism that ensures product safety is continuously achieved. The entire production process of By-products feed production was evaluated using HACCP wizard software. This includes the plant layout, technical standards, storage and fermentation tank cleansing method, staff assignment, safety control method, and distribution. The potential biological, chemical, and physical hazards that may exist in every step of the production process were identified, and then critical control points (CCPs) were selected. This will ensure the safety of products made from livestock that consumes by-product feed. These includes cheese, milk, beef, etc.

• The KIPS Transactions:PartD
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• v.16D no.6
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• pp.911-920
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• 2009

Airbone software must comply the DO-178B standard in order to be certified by the FAA. The standard requires the unit testing of safety-critical software to meet the coverage criterion called MC/DC(Modified Condition/Decision Coverage). Although MC/DC is known to be effective in finding errors related to safety, it is also true that generating test cases which satisfy the MC/DC criterion is not easy. This paper presents a tool named MD-SAT which generates MC/DC test cases with SAT(SATisfiability) technology. It can be employed for generating diverse test cases in tools implementing various testing techniques including decision table based test, cause-effect graphing, and state-based test.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.3
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• pp.441-450
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• 2022

The introduction of autonomous underwater gliders (AUGs) specifically addresses the reduction of operational costs that were previously prohibited with conventional autonomous underwater vehicles (AUVs) using a "scaling-down" design philosophy by utilizing the characteristics of autonomous drifters to far extend operation duration and coverage. Long-duration, wide-area missions raise the cost and complexity of in-water testing for novel approaches to autonomous mission planning. As a result, a simulator that supports the rapid design, development, and testing of autonomy solutions across a wide range using software-in-the-loop simulation at faster-than-real-time speeds becomes critical. This paper describes a faster-than-real-time AUG simulator that can support high-resolution bathymetry for a wide variety of ocean environments, including ocean currents, various sensors, and vehicle dynamics. On top of the de facto standard ROS-Gazebo framework and open-sourced underwater vehicle simulation packages, features specific to AUGs for ocean mapping are developed. For vehicle dynamics, the next-generation hybrid autonomous underwater gliders (Hybrid-AUGs) operate with both the buoyancy engine and the thrusters to improve navigation for bathymetry mappings, e.g., line trajectory, are is implemented since because it can also describe conventional AUGs without the thrusters. The simulation results are validated with experiments while operating at 120 times faster than the real-time.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.04a
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• pp.700-703
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• 2017

안전 필수 소프트웨어란, 소프트웨어의 결함으로 인해 사고가 일어났을 경우 사용자에게 치명적인 위해를 야기하는 소프트웨어를 의미한다. 안전 필수 소프트웨어는 다양한 산업에서 보편화 되고 있기 때문에 안전성이 확보된 소프트웨어를 사용자에게 제공해야하며, 잠재적인 결함이 사고로 이어질 수 있기에 안전 요소들에 대한 충분한 분석이 필요하다. 요구사항으로부터 위험 요소를 분석할 때에는 결함의 결과만을 보고 위험 등급을 부여하는 한계가 있다. 결함의 결과가 비록 같더라도 각기 다른 원인에 의해서 각기 다른 위험 수준을 갖기 때문이다. 본 논문에서는 각각의 기능들에 대해 안전성을 부여하고 우선순위를 선정하여 위험도가 높은 기능들에 대해서 우선적으로 분석할 수 있는 기법에 대해서 제안한다.

• IE interfaces
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• v.19 no.1
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• pp.62-69
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• 2006

In these days companies are rapidly implementing the extended enterprise collaboration to provide enhanced management services and products based on the enterprise integration that human resources, technologies and the management process. In this corporate environment, ASP (Application Service Provider) which is the developed type of outsourcing in the area of information technology, is a good alternative for corporate information system management. ASP defines as a software leasing service which is supplied through networks instead of purchasing application software with high price. For successful implementation of ASP, it is necessary to develop the certification methodology to ensure safety and reliability of ASP. The paper provides the safe and reliable certification methodology for ASP. In order to develop it, the critical issues related to service quality and certification of ASP are identified and the systematic certification methodology of application and service provider(service environment) domains of ASP are provided. A evaluation method for the developed certification methodology is also proposed.

• Journal of Advanced Navigation Technology
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• v.20 no.2
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• pp.127-133
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• 2016

This paper proposes a case study of applying to DO-278A, which is a software development standard of ground aviation equipment in communication, navigation, surveillance/air traffic management (CNS/ATM) domain, in order to develop software of Advanced surface movement, guidance and control system (A-SMGCS). It explains considerations to application of DO-278A standard, discusses how to tailor processes or requirements specified in DO-278A in detail, and explain tailored results. And it also summary problems or issues occurred during application of DO-278A, which can be appeared when DO-278A is applied to for the first time by any development part. These are required considerations in order to reduce trial and error. To the conclusion, it explains lessons learned from application of DO-278A and suggest how to solve these problems or issues.

• Journal of KIISE:Software and Applications
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• v.29 no.12
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• pp.860-872
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• 2002

Fault tree analysis is the most widely used saftly analysis technique in industry. However, the analysis is often applied manually, and there is no systematic and automated approach available to validate the analysis result. In this paper, we demonstrate that a real-time model checker UPPAAL is useful in formally specifying the required behavior of safety-critical software and to validate the accuracy of manually constructed fault trees. Functional requirements for emergency shutdown software for a nuclear power plant, named Wolsung SDS2, are used as an example. Fault trees were initially developed by a group of graduate students who possess detailed knowledge of Wolsung SDS2 and are familiar with safety analysis techniques including fault tree analysis. Functional requirements were manually translated in timed automata format accepted by UPPAAL, and the model checking was applied using property specifications to evaluate the correctness of the fault trees. Our application demonstrated that UPPAAL was able to detect subtle flaws or ambiguities present in fault trees. Therefore, we conclude that the proposed approach is useful in augmenting fault tree analysis.