Kim, BaekGyu
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Publication A Safety Case Pattern for Model-Based Development Approach(2012-04-01) Ayoub, Anaheed; Kim, BaekGyu; Lee, Insup; Sokolsky, OlegIn this paper, a safety case pattern is introduced to facilitate the presentation of a correctness argument for a system implemented using formal methods in the development process. We took advantage of our experience in constructing a safety case for the Patient Controlled Analgesic (PCA) infusion pump, to define this safety case pattern. The proposed pattern is appropriate to be instantiated within the safety cases constructed for systems that are developed by applying model-based approaches.Publication A Causality Analysis Framework for Component-Based Real-Time Systems(2013-09-01) Wang, Shaohui; Ayoub, Anaheed; Kim, BaekGyu; Sokolsky, Oleg; Lee, Insup; Gössler, GregorWe propose an approach to enhance the fault diagnosis in black-box component-based systems, in which only events on component interfaces are observable, and assume that causal dependencies between component interface events within components are not known. For such systems, we describe a causality analysis framework that helps us establish the causal relationship between component failures and system failures, given an observed system execution trace. The analysis is based on a formalization of counterfactual reasoning, and applicable to real-time systems. We illustrate the analysis with a case study from the medical device domain.Publication Platform-Specific Code Generation from Platform-Independent Timed Models(2015-12-01) Kim, BaekGyu; Feng, Lu; Sokolsky, Oleg; Lee, InsupMany safety-critical real-time embedded systems need to meet stringent timing constraints such as preserving delay bounds between input and output events. In model-based development, a system is often implemented by using a code generator to automatically generate source code from system models, and integrating the generated source code with a platform. It is challenging to guarantee that the implemented systems preserve required timing constraints, because the timed behavior of the source code and the platform is closely intertwined. In this paper, we address this challenge by proposing a model transformation approach for the code generation. Our approach compensates the platform-processing delays by adjusting the timing parameters in system models, based on an Integer Linear Programming problem formulation. We demonstrate the usefulness of our approach via a case study of infusion pump systems. Experimental results show that the code generated using our approach can better preserve the timing constraints.Publication The Medical Device Dongle: An Open-Source Standards-Based Platform for Interoperable Medical Device Connectivity(2012-01-28) Asare, Philip; Cong, Danyang; Vattam, Santosh G.; Kim, BaekGyu; King, Andrew; Sokolsky, Oleg; Lee, Insup; Lin, Shan; Mullen-Fortino, MargaretEmerging medical applications require device coordination, increasing the need to connect devices in an interoperable manner. However, many of the existing health devices in use were not originally developed for network connectivity and those devices with networking capabilities either use proprietary protocols or implementations of standard protocols that are unavailable to the end user. The first set of devices are unsuitable for device coordination applications and the second set are unsuitable for research in medical device interoperability. We propose the Medical Device Dongle (MDD), a low-cost, open-source platform that addresses both issues.Publication A Layered Approach for Testing Timing in the Model-Based Implementation(2014-03-01) Kim, BaekGyu; Hwang, Hyeon I.; Park, Taejoon; Lee, Insup; Son, Sang H.The model-based implementation is to derive an implementation from a model that has been shown to meet requirements. Even though this approach can be used to guarantee that an implementation satisfies functional requirements that are shown to be correct at the model level, it is still challenging to assure timing requirements at the implementation level. We propose a layered approach in testing timing requirements conformance of implemented systems developed by model-based implementation. In our approach, the abstraction boundary of the implemented system is formally defined using Parnas' four-variables model. Then, the proposed approach tests timing aspects of the interaction between the auto-generated code and the target platform-dependent code based on the four-variables. This approach aims at not only detecting the timing requirement violation, but also at measuring delay-segments that contribute to the timing deviation of the implemented system w.r.t. the model. We show the case study of testing timing requirements of an infusion pump system to illustrate the applicability of the proposed framework.Publication A Systematic Approach to Justifying Sufficient Confidence in Software Safety Arguments(2012-06-15) Ayoub, Anaheed; Kim, Baekgyu; Lee, Insup; Sokolsky, OlegSafety arguments typically have some weaknesses. To show that the overall confidence in the safety argument is considered acceptable, it is necessary to identify the weaknesses associated with the aspects of a safety argument and supporting evidence, and manage them. Confidence arguments are built to show the existence of sufficient confidence in the developed safety arguments. In this paper, we propose an approach to systematically constructing confidence arguments and identifying the weaknesses of the software safety arguments. The proposed approach is described and illustrated with a running example.