• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.6
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• pp.1200-1207
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• 2009

The GMDH(Group Method of Data Handling) algorithm can be used to model the complex nonlinear systems. The traditional GMDH algorithm produces the output of the system model in the output layer through the input layer and the intermediate layers as the prescribed process. The outputs of each layer are produced only by the outputs of the former layer. However among the inputs there may be the inputs which can influence the modeling result more than the other inputs. Therefore in this paper the method which improve the modeling capability by interlayer connection of more influential inputs is proposed. The capability improvement of the proposed algorithm compared to the traditional algorithm is verified through computer simulation.

• Journal of Institute of Control, Robotics and Systems
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• v.2 no.3
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• pp.209-219
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• 1996

Fieldbus provides a real-time data communication among field devices in the process control and manufacturing automation systems. In this paper, a Petri Net model of the 1993 draft of IEC/ISA fieldbus which is proposed as an international standard of fieldbus network is developed. Based on the Petri Net model, discrete-event simulation model of IEC/ISA fieldbus network is developed. This paper evaluates the network induced delay in the data link layer of IEC/ISA fieldbus using the simulation model. In addition, an integrated discrete-event/continuous-time simulation model of fieldbus system and distributed control system is developed. This paper investigates the real-time data processing capability of IEC/ISA fieldbus and the effect of network-induced delay to the performance of control system.

• Nuclear Engineering and Technology
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• v.45 no.6
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• pp.759-766
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• 2013

As passive safety features for nuclear power plants receive increasing attention, various studies have been conducted to develop safety systems for 3rd-generation (GEN-III) nuclear power plants that are driven by passive systems. The Passive Auxiliary Feedwater System (PAFS) is one of several passive safety systems being designed for the Advanced Power Reactor Plus (APR+), and extensive studies are being conducted to complete its design and to verify its feasibility. Because the PAFS removes decay heat from the reactor core under transient and accident conditions, it is necessary to evaluate the heat removal capability of the PAFS under hypothetical accident conditions. The heat removal capability of the PAFS is strongly dependent on the heat transfer at the condensate tube in Passive Condensation Heat Exchanger (PCHX). To evaluate the model of heat transfer coefficient for condensation, the Multi-dimensional Analysis of Reactor Safety (MARS) code is used to simulate the experimental results from PAFS Condensing Heat Removal Assessment Loop (PASCAL). The Shah model, a default model for condensation heat transfer coefficient in the MARS code, under-predicts the experimental data from the PASCAL. To improve the calculation result, The Thome model and the new version of the Shah model are implemented and compared with the experimental data.

• Journal of Electrical Engineering and Technology
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• v.3 no.2
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• pp.143-151
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• 2008

This paper presents the operation of Fuel Cell Distributed Generation(FCDG) systems in distribution systems. Hence, modeling, controller design, and simulation study of a Solid Oxide Fuel Cell(SOFC) distributed generation(DG) system are investigated. The physical model of the fuel cell stack and dynamic models of power conditioning units are described. Then, suitable control architecture based on fuzzy logic and the neural network for the overall system is presented in order to activate power control and power quality improvement. A MATLAB/Simulink simulation model is developed for the SOFC DG system by combining the individual component models and the controllers designed for the power conditioning units. Simulation results are given to show the overall system performance including active power control and voltage regulation capability of the distribution system.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.2
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• pp.235-242
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• 2010

DSTC(Defense Systems Test Center) in ADD(Agency for Defense Development) performs a test for various kinds of weapon system. In order to provide accurate test measurement data relating to the weapon system's performance with customer, A reliable test process and an objective analysis of the measurement data are required. DSTC is trying to apply CMMI(Capability Maturity Model Integration) Ver 1.2 in a test process. In this paper, we present the result of CMMI Engineering Process Area Modelling of Test Process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.725-732
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• 2016

To develop large-scale complex systems, many organizations have attempted to improve the processes specified in systems engineering (SE) and project management (PM) by adopting CMMI (Capability Maturity Model Integration). On the other hand, most domestic organizations that already acquired CMMI level 3 have focused on SE&PM practices while providing less investment in building up the environment for institutionalizing those processes. In such organizations, the process maturity without advancing to institutionalization can be neither enhanced nor maintained. To resolve the problem, the following remedies can be suggested. A standard process should first be defined to meet the business mission of the organization and to carry out the process successfully, the people should be properly trained and the appropriate tools be provided. In this study, a maturity model to accomplish institutionalization was examined based on the aforementioned P-P-T (Process-People-Tool) concept. The model proposed would be useful in developing strategies and plans for process institutionalization when the organizations are in the preparation stages for a CMMI certificate or have already acquired one.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1814-1821
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• 2012

As a new Korean grid code which includes LVRT requirement to wind farm of which capacity is greater than 20MW is activated in 2012, this paper developed the analytical model of the Korean LVRT for the simulation based feasibility study of the wind farm interconnection into power systems. The developed model of the LVRT is verified by applying it into the performance evaluation of the wind farm interconnected power systems and the effect of Korean LVRT is analyzed through case studies considering typical disturbances of power systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.3
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• pp.358-379
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• 2010

Multiple object association is an important capability in visual surveillance system with multiple cameras. In this paper, we introduce locally initiating line-based object association with the parallel projection camera model, which can be applicable to the situation without the common (ground) plane. The parallel projection camera model supports the camera movement (i.e. panning, tilting and zooming) by using the simple table based compensation for non-ideal camera parameters. We propose the threshold distance based homographic line generation algorithm. This takes account of uncertain parameters such as transformation error, height uncertainty of objects and synchronization issue between cameras. Thus, the proposed algorithm associates multiple objects on demand in the surveillance system where the camera movement dynamically changes. We verify the proposed method with actual image frames. Finally, we discuss the strategy to improve the association performance by using the temporal and spatial redundancy.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.2
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• pp.65-73
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• 2018

The dynamic capabilities of sensing market signals, creating new opportunities and reconfiguring resources and capabilities to new opportunities in a rapidly changing economic environment determines the competitiveness of the enterprise to create added value and survival. This study conceptualized a two-stage performance measurement framework based on the casual model of resource (input)-process-performance (output). We have developed a 'Process capability index' that reflect the dynamic capabilities factors as a key intermediary product linking resource inputs and performance outputs in enterprise performance measurement. The process capability index consists of four elements : manpower (level of human resource), operation productivity, structure and risk management. The DEA (Data Envelopment Analysis) model was applied to the developed performance indicators to analyze the branch office performance of a telecom company. Process capability efficiency (stage 1) uses resource inputs to reach a certain level of process capabilities. In performance result efficiency (stage 2), the process capabilities are used to generate sales revenues and subscribers. The two-stage DEA model derives intermediate output values that optimize the individual stages simultaneously. Some branch offices in the telecom company have focused on process capability efficiency or some other branch offices focused on performance result efficiency. Positioning map using two-stage efficiency decomposition and benchmarking can help identify the sources of inefficiencies and visualize strategic directions for performance optimization. Applications of two-stage DEA in conjunction with the case study that are meaningfully used in performance measurement areas have been scarce. In particular, this paper has the contribution to present a new performance measurement model considering the organization theory, the dynamic capabilities.

• Journal of the Korean Institute of Intelligent Systems
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• v.4 no.1
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• pp.35-49
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• 1994

It is well known that, for nominimum phase systems, a conventional linear controller of PID type or an adaptive controller of this structure shows limitation in achieving a satisfactory performance under tight specifications. In this paper, we combine a neuro-controller with a PI-controller with off-line learning capability provided by the Genetic Algorithm to propose a novel neuro-controller to control nonminimum phase systems effectively. The simulation results show that our proposed model is more efficient with faster rising time and less undershoot effect when the performances of the proposed controller and a conventional form are compared.