Jinkyung Kim

Synthesis of safe operating procedure for multi-purpose batch processes using SMV

Abstract Symbolic model verifier (SMV), an automatic error finding system, is developed and applied to various chemical processing systems to test their safety and feasibility. In this paper, we adopted SMV to synthesize error-free operating schedules in multi-purpose batch processes. The strength of this method is to synthesize a feasible sequence and to verify its safety simultaneously. Here, we propose two algorithms. One is to find embedded errors in operating sequences such as violating intermediate storage tank policies and unavailability due to sudden operating condition changes or insufficient production recipes. The other is the completion time algorithm to make sure that a makespan and a final operating sequence are obtained without errors. The proposed algorithm identifies errors and finds a minimum makespan and an operating sequence. Computation tree logic (CTL) embedded in SMV is extensively used to describe the situation of unsafe conditions and time related conditions for the final makespan. As a result of applying the algorithms to multi-purpose chemical processes, this approach finds a makespan and error-free operating schedules successfully. This combined synthesis and verification method also reduces the computation time and verifies operating schedules efficiently compared with the previously published algorithms.

Graphical modeling for the safety verification of chemical processes

Abstract This study focuses on verifying the safety using graphical modeling and simulation for chemical processes logics. UPPAAL is used as an integrated tool for modeling, simulation and verification in this study. Most of chemical processes are highly automated and they are represented by complex network control logics. The safety analysis of these chemical processes is always difficult or sometimes impossible to verify the system perfectly because the system includes dynamic variables, various levels of control activities (safety interlocking, regulatory/discrete control and sequential control), numerous units, instruments and control software/hardware. All these must be considered simulteneously, therefore, this study presents an effective technique for the safety verification using a graphical modeling and simulation.

Improved search algorithm for the efficient verification of chemical processes

Abstract The safety verification of chemical processing systems becomes more difficult due to their complexity. Current search methods suffer from the state explosion problem, mainly because the verification problem itself is inherently complex considering numerous units (reactor, distillation column, storage tank), instruments (valve, pump), control software and many other components, and more importantly considering time. This paper focuses on methods of improving the search algorithm in its efficiency. The algorithm enables to prune out the state transition paths that cannot happen in the behavior of process equipment and operating procedures in system modeling. The state transition structure constructed by this algorithm becomes enormously smaller in its search space. Computing time is also reduced and safety verifications of more complex processes and operating procedures become possible.

Automatic Verification of Biochemical Network Using Model Checking Method

Abstract This study focuses on automatic searching and verifying methods for the reachability, transition logics and hierarchical structure in all possible paths of biological processes using model checking. The automatic search and verification for alternative paths within complex and large networks in biological process can provide a considerable amount of solutions, which is difficult to handle manually. Model checking is an automatic method for verifying if a circuit or a condition, expressed as a concurrent transition system, satisfies a set of properties expressed in a temporal logic, such as computational tree logic (CTL). This article represents that model checking is feasible in biochemical network verification and it shows certain advantages over simulation for querying and searching of special behavioral properties in biochemical processes.

Modeling and verification of control logics in safety instrumented system for chemical industrial processes

Abstract This study focuses on automatic verification and validation methods for the safety and correctness of control logics of the safety instrumented system (SIS) in chemical process industry. The models of discrete events, system behaviors and control programs for chemical processes and SIS are developed using automata theory. Symbolic model checking method, an automatic error finding approach, is used to verify its safety and reliability. The strength of this method is to synthesize a feasible sequence through a counter-example and to verify its correctness using computation tree logic (CTL) simultaneously. This method can be applied to determine the error-free location of SIS, to find the logical errors automatically which is difficult to find manually, and to verify the safety and feasibility of SIS. This paper addresses the model development of the SIS control logics of chemical industrial processes and presents how model checking approach can be used efficiently in the verification of SIS control logics through several case studies.