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In this study, an engineering economics software was developed to find the optimum design of renewable energy systems in micro-grid, off-grid, and on-grid cases. The software was used to calculate the renewable energy production from photovoltaic and wind turbines in local regions in Korea. TMY2 files were made for the renewable energy calculation based on meteorological data from 28 locations in Korea. To calculate the output of the photovoltaic and the wind turbine, a power generation model based on theoretical equations was developed. A fuel cell and diesel engine generator can be selected to use as a base power source model, and a battery energy storage device was included for efficient energy management. To verify the results of renewable power generations from solar and wind, the models were compared with commercial programs such as TRNSYS and HOMER. The results showed good agreement under the same conditions. A sensitivity analysis for a grid-connected factory in a specific region was carried out and the optimum investment design condition for a renewable energy system to reduce costs through peak load reduction was calculated. The sensitivity analysis for off-grid and grid-connected system designs was also performed and it will be continued to improve the accuracy of the model by comparing the data with that from a demonstration complex. The developed program can provide useful information for investment decisions through the optimal design of facility capacity and economic analysis when investing in renewable energy supply facilities.

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The time-triggered message-triggered object (TMO) has been devised as the basic component model for highlevel distributed real-time programming as well as realtime application systedsubsystem design and modeling. One of the strengths of the TMO is its facilitation of multiphased top-down modeling of real-time distributed computing application systems. TMO-structured models are capable of representing both a real-time control system and its controlled facilities (composed of sensors, actuators, and monitored infrastructure) in a uniform fashion. Also, TMO-structured real-time simulation models can be generated in attractively simple forms and they can be executed to enable examination of not only the logical accuracy of a real-time control system being developed but also the correctness of its timing behavior. A case study of such simulation modeling has been conducted in the context of constructing a real-time simulator of a real-time control system called the safety injection system (SIS) which is a subsystem of a nuclear power plant. In the course of this case study, some tools that support efficient real-time simulation have been developed. The refined modeling steps, the support tools developed, and the cost-effectiveness confirmed in the course of this case study are the main subjects discussed in this paper.