• IEMEK Journal of Embedded Systems and Applications
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• v.14 no.5
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• pp.227-237
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• 2019

Ultra-low latency control is one of the characteristics of 5G cellular network services, which means that the control loop is handled in milliseconds. To achieve this, it is necessary to identify time delay factors that occur in all components related to CPS control loop, including new 5G cellular network elements such as MEC, and to optimize CPS control loop in real time. In this paper, a novel CPS architecture for ultra-low latency control of CPS is designed. We first define the ultra-low latency characteristics of CPS and the CPS concept model, and then propose the design of the control loop performance monitor (CLPM) to manage the timing information of CPS control loop. Finally, a case study of MEC-based implementation of ultra-low latency CPS reviews the feasibility of future applications.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.374-377
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• 2002

In this paper, the control system of the MagLev system for a CPS is designed and implemented. The target to be controlled is PEM(permanent and electromagnet) type with 4-comers levitation which is open-loop unstable, highly non-linear and time-varing system. The designed controller is validated by some kinds of experiments.

• IEMEK Journal of Embedded Systems and Applications
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• v.7 no.5
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• pp.267-275
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• 2012

In this paper, we present the model-based autonomic computing framework for a cyber-physical system which provides a self-management and a self-adaptation characteristics. A development process using this framework consists of two phases: a design phase in which a developer models faults, normal status constrains, and goals of the CPS, and an operational phase in which an autonomic computing engine operates monitor-analysis-plan-execute(MAPE) cycle for managed resources of the CPS. We design a hierachical architecture for autonomic computing engines and adopt the Model Reference Adaptive Control(MRAC) as a basic feedback loop model to separate goals and resource management. According to the GroundVehicle example, we demonstrate the effectiveness of the framework.

• Journal of the Korean Society of Systems Engineering
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• v.11 no.2
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• pp.95-105
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• 2015

Manufacturing Execution System(MES) is in charge of manufacturing execution in the shop floor based on the inputs given by high level information such as ERP, etc. The typical MES implemented is not tightly interconnected with shop floor control system including real (or near real) time monitoring and control devices such as PLC. The lack of real-time interfaces is one of the major obstacles to achieve accurate and optimization of the total performance index of the shop floor system. Smart factory system in the paradigm of Industry 4.0 tries to solve the problems via CPS (Cyber Physical System) technology and FILS (Factory In-the-Loop System). In this paper, we conducted Systems Engineering Approach to design an advanced MES (namely Smart MES) that can accommodate CPS and FILS concept. Specifically, we tailored Systems Engineering Process (SEP) based on an International Standard formalized as ISO/IEC 15288 to develop Stakeholders' Requirements (StR), System Requirements (SyR). The deliverables of each process are modeled and represented by the SysML, UML customized to Systems Engineering. The results of the research can provide a conceptual framework for future MES that can play a crucial role in the Smart Factory.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.2
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• pp.49-56
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• 2008

In order to reduce energy consumption, secondary controlled system has been applied to many types of equipments. In lifting equipments or press machines using hydraulic cylinder, a hydraulic transformer is used as a control component instead of a valve for motion control and a component for recovering potential energy of load. The transformer is a combination of a variable displacement pump/motor as a secondary controlled element and a fixed displacement pump/motor. In this paper the effect of transformer is studied. Multiple closed loop controllers with displacement feedback of variable pump/motor, speed feedback and position feedback of cylinder are used. The efficiency and energy consumption when cylinder is driven up and down is calculated by simulation. Simulation results show that considerable energy saving is achieved by choosing load ratio, circuit type and supply pressure.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1075-1080
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• 2007

In order to reduce energy consumption, secondary controlled system has been applied to many types of equipments. In lifting equipments or press machines using hydraulic cylinder, a hydraulic transformer is used as a control component instead of a valve for motion control and a component for recovering potential energy of load. The transformer is a combination of a variable displacement pump/motor as a secondary controlled element and a fixed displacement pump/motor. In this paper the effect of transformer is studied. Multiple closed loop controllers with displacement feedback of variable pump/motor, speed feedback and position feedback of cylinder are used. The efficiency and energy consumption when cylinder is driven up and down is calculated by simulation. Simulation results show that considerable energy saving is achieved by choosing load ratio, circuit type and supply pressure.