Kim, BaekGyu

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2011 - 20157
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  • Publication
    A Model-Based I/O Interface Synthesis Framework for the Cross-Platform Software Modeling
    (2012-10-01) Kim, BaekGyu; Phan, Linh T.X.; Lee, Insup; Sokolsky, Oleg
    In model-based development, executable software (e.g., C or Java code) can be generated from a high-level model using a code generator. However, the execution of the generated software on a target platform remains a challenge due to a mismatch in communication semantics assumed by the model and the platform-dependent software (e.g., sampling/actuation routines). This paper proposes an input/output (I/O) interface module that bridges this semantic gap by means of buffers and interface policies, which explicitly capture the information required to adapt the model’s communication semantics to that of the platform. We present a framework that can be used to systematically synthesize – directly from the model – the I/O interfaces and accompanying APIs that the generated software and the platform-dependent software need to communicate with one another. Our interface policies can also encode relaxations of a model semantics that may not be implementable, thus making derivations of the implemented systems from the model traceable. We illustrate the applicability and the benefits of our framework with a case study of an infusion pump.
  • Publication
    From Requirements to Code: Model Based Development of a Medical Cyber Physical System
    (2014-07-01) Murugesan, Anitha; Heimdahl, Mats; Whalen, Michael; Kim, BaekGyu; Rayadurgam, Sanjai; Sokolsky, Oleg; Komp, John; Lee, Insup; Duan, Lian
    The advanced use of technology in medical devices has improved the way health care is delivered to patients. Unfortunately, the increased complexity of modern medical devices poses challenges for development, assurance, and regulatory approval. In an e ort to improve the safety of advanced medical devices, organizations such as FDA have supported exploration of techniques to aid in the development and regulatory approval of such systems. In an ongoing research project, our aim is to provide effective development techniques and exemplars of system development artifacts that demonstrate state of the art development techniques. In this paper we present an end-to-end model-based approach to medical device software development along with the artifacts created in the process. While outlining the approach, we also describe our experiences, challenges, and lessons learned in the process of formulating and analyzing the requirements, modeling the system, formally verifying the models, generating code, and executing the generated code in the hardware for generic patient controlled analgesic infusion pump (GPCA). We believe that the development artifacts and techniques presented in this paper could serve as a generic reference to be used by researchers, practitioners, and authorities while developing and evaluating cyber physical medical devices.
  • Publication
    Executing Model-Based Tests on Platform-Specific Implementations
    (2015-11-01) You, Dongjiang; Rayadurgam, Sanjai; Heimdahl, Mats; Kim, BaekGyu; Komp, John; Sokolsky, Oleg
    Model-based testing of embedded real-time systems is challenging because platform-specific details are often abstracted away to make the models amenable to various analyses. Testing an implementation to expose non-conformance to such a model requires reconciling differences arising from these abstractions. Due to stateful behavior, naive comparisons of model and system behaviors often fail causing numerous false positives. Previously proposed approaches address this by being reactively permissive: passing criteria are relaxed to reduce false positives, but may increase false negatives, which is particularly bothersome for safety-critical systems. To address this concern, we propose an automated approach that is proactively adaptive: test stimuli and system responses are suitably modified taking into account platform-specific aspects so that the modified test when executed on the platform-specific implementation exercises the intended scenario captured in the original model-based test. We show that the new framework eliminates false negatives while keeping the number of false positives low for a variety of platform-specific configurations.
  • Publication
    Safety-Assured Development of the GPCA Infusion Pump Software
    (2011-10-01) Kim, BaekGyu; Ayoub, Anaheed; Sokolsky, Oleg; Lee, Insup; Jones, Paul; Zhang, Yi; Jetley, Raoul
    This paper presents our effort of using model-driven engineering to establish a safety-assured implementation of Patient-Controlled Analgesic (PCA) infusion pump software based on the generic PCA reference model provided by the U.S. Food and Drug Administration (FDA). The reference model was first translated into a network of timed automata using the UPPAAL tool. Its safety properties were then assured according to the set of generic safety requirements also provided by the FDA. Once the safety of the reference model was established, we applied the TIMES tool to automatically generate platform-independent code as its preliminary implementation. The code was then equipped with auxiliary facilities to interface with pump hardware and deployed onto a real PCA pump. Experiments show that the code worked correctly and effectively with the real pump. To assure that the code does not introduce any violation of the safety requirements, we also developed a testbed to check the consistency between the reference model and the code through conformance testing. Challenges encountered and lessons learned during our work are also discussed in this paper.
  • Publication
    Platform-Dependent Code Generation for Embedded Real-Time Software
    (2013-09-29) Kim, BaekGyu; Phan, Linh T.X.; Sokolsky, Oleg; Lee, Insup
    Code generation for embedded systems is challenging, since the generated code (e.g., C code) is expected to run on a heterogeneous set of target platforms with different characteristics, such as hardware/software architectures and programming interfaces. We propose a code generation framework that provides the flexibility to generate different source code that is executable on each target platform. In our framework, the platform-dependent characteristics of a target platform are explicitly specified by an Architectural Analysis Description Language (AADL) model and a code snippet repository. The AADL model captures hardware/software architectural aspects of the platform, such as periodic/aperiodic threads and their interactions with sensors and actuators. The code snippet repository contains platform-dependent code snippets that are categorized according to the functions required to implement the components of the AADL model. These two elements of the platform capability are then used by the code generation algorithm to generate platform-dependent code for the given platform. We demonstrate the applicability of our framework using a case study of code generation for two infusion pump systems.
  • Publication
    Platform-Specific Timing Verification Framework in Model-Based Implementation
    (2015-03-01) Kim, BaekGyu; Feng, Lu; Phan, Linh T. X; Sokolsky, Oleg; Lee, Insup
    In the model-based implementation methodology, the timed behavior of the software is typically modeled independently of the platform-specific timing semantics such as the delay due to scheduling or I/O handling. Although this approach helps to reduce the complexity of the model, it leads to timing gaps between the model and its implementation. This paper proposes a platform-specific timing verification framework that can be used to formally verify the timed behavior of an implementation that has been developed from a platform-independent model. We first describe a way to categorize the interactions among the software, a platform, and the environment in the form of implementation schemes. We then present an algorithm that systematically transforms a platform-independent model into a platform-specific model under a given implementation scheme. This transformation algorithm ensures that the timed behavior of the platform-specific model is close to that of the corresponding implementation. Our case study of an infusion pump system shows that the measured timing delay of the system is bounded by the formally verified bound of its platform-specific model.
  • Publication
    Challenges and Research Directions in Medical Cyber-Physical Systems
    (2012-01-01) Lee, Insup; Sokolsky, Oleg; Chen, Sanjian; Hatcliff, John; Jee, Eunkyoung; Kim, BaekGyu; King, Andrew; Mullen-Fortino, Margaret; Park, Soojin; Roederer, Alexander; Venkatasubramanian, Krishna
    Medical cyber-physical systems (MCPS) are lifecritical, context-aware, networked systems of medical devices. These systems are increasingly used in hospitals to provide highquality continuous care for patients. The need to design complex MCPS that are both safe and effective has presented numerous challenges, including achieving high assurance in system software, intoperability, context-aware intelligence, autonomy, security and privacy, and device certifiability. In this paper, we discuss these challenges in developing MCPS, some of our work in addressing them, and several open research issues