• International Journal of Automotive Technology
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• 제8권3호
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• pp.299-308
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• 2007

This study proposes a two-layer hierarchical control system that integrates active front wheel steering and four wheel braking torque control to improve vehicle handling performance and stability. The first layer is a robust model matching controller (R-MMC) based on linear matrix inequalities (LMIs), which optimizes an active front steering angle compensation and a desired yaw moment control, and calculates reference wheel slip for the target wheel according to the desired yaw moment. The second layer is a moving sliding mode controller (MSMC) that can track the reference wheel slip in a predetermined time by commanding proper braking torque on the target wheel to achieve the desired yaw moment. Since vehicle sideslip angle measurement is difficult to achieve in practice, a sliding mode observer (SMO) that requires only vehicle yaw rate as the measured input is also developed in this study. The performance and robustness of the SMO and the integrated control system are demonstrated through comprehensive computer simulations. Simulation results reveal the satisfactory tracking ability of the SMO, and the superior improved vehicle handling performance, stability and robustness of the integrated control vehicle.

• 한국해양공학회지
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• 제24권2호
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• pp.1-9
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• 2010

Oscillating Water Column is one of the most widely used converting systems all over the world. The operating performance is influenced by the efficiencies of the two converting stages in the OWC chamber-turbine integrated system. In order to study the effects of the pressure drop induced by the air turbine, the experiments using the impulse turbine and the orifice device are carried out in the wave simulator test rig. The numerical simulation utilizing the orifice and porous media modules is calculated and validated by the corresponding experimental data. The numerical wave tank based on the two-phase VOF model embedded with the above modules is employed to investigate the wave elevation, pressure variation inside the chamber and the air flow velocity in the duct. The effects of the air turbine on the integrated system and interaction among the wave elevation, pressure and air flow velocities variations are investigated, which demonstrates that the present numerical model are more accurate to be employed.

• 산업공학
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• 제6권2호
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• pp.133-150
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• 1993

Recent industrial efforts are directed toward the development of CIM(Computer integrated Manufacturing) system. It is often the case that the analysis of the system dynamic behaviour is overlooked, even if it is important for both the economic justification and system performance evaluation. The main purpose of this study is to present a n approach of system performance evaluation for PCB(Printed Circuit Board) manufacturing, especially the inner layer manufacturing processes, using simulation. The general overview of the PCB manufacturing environment has first been discussed. Then a computer simulation program which can consider the diverse dynamic environmental changes has been developed. Extensive system analyses have been performed based on the program developed and the three measures proposed. The results obtained in this study provide valuable guidelines for practical concerns and some recommendations for future extensions.

• 한국시뮬레이션학회논문지
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• 제2권1호
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• pp.1-12
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• 1993

Simulation has been recognized as an invaluable tool in designing and analyzing manufacturing system. In this paper, a Petri net based simulation tool to facilitate the simulation project in manufacturing area is presented . To simulate a manufacturing system, three models are developed ; a Petrinet model, a monitor, and a token control function. While hardware objects in manufacturing systems are modeled by Petri net objects, cell level control functions are separately modeled and integrated with a Petri net model so that they resolve conflicts occuring in Petri net execution. The monitor is a model regarding the information flow between Petri nets and token control functions. The facilities of the developed tool are presented. Also, a modeling procedure with the tool is illustrated via a case study.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2005년도 춘계학술대회 논문집
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• pp.123-128
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• 2005

War-game modeling and simulation system have been developed and applied to virtual tactical training both inside and outside of country However, most existing models have been developed for individual purpose based on the simple platform modeling such as physical modeling, visual modeling, and conceptual modeling. Thus, those modeling and simulation system cannot support the interoperability, expensively, variety and reusability. To deal with these problems, the paper propose an integrated design methodology for the War-game systems based on the DEVS/HLA.

• Journal of Electrical Engineering and Technology
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• 제10권5호
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• pp.1969-1982
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• 2015

The virtual inertia control (VIC) of wind turbine with directly-driven permanent-magnet synchronous generator (D-PMSG) can act similarly to the conventional synchronous generator in inertia response and frequency control, thereby supporting the system frequency stability. However, because the wind speed is inconstant and changeable to a certain extent and the D-PMSG is a complex nonlinear system, there are great difficulties in the virtual inertia optimal control of the D-PMSG. Based on the design principle of the active disturbance rejection control (ADRC), this paper presents a new VIC strategy for the D-PMSG from the perspective of power disturbance suppression in the system. The strategy helps fulfill the power grid disturbance estimation and compensation by means of the extended state observer (ESO) so as to improve the disturbance-resisting performance of the system. Compared with conventional proportional-derivative virtual inertia control (PDVIC), this method, which is of better adaptability and robustness, can not only improve the property of the D-PMSG responding to the system frequency but also reduce the influence of wind speed disturbance. The simulation and experiment results have verified the effectiveness and feasibility of the VIC based on the ADRC.

• 한국시뮬레이션학회논문지
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• 제24권1호
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• pp.9-16
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• 2015

본 논문에서는 표준연동 아키텍처(HLA/RTI)기반 다해상도 연동이 가능한 시뮬레이션을 구성하여 공학급(QUEST), 교전급(SADM), 임무급(EADSIM)의 모델을 연동하였다. 공학급 모델은 전투실험 공학분석 시범체계에서 개발된 전투실험 통합개발환경(QUEST)을 이용하여 모델을 개발하였다. 교전급 모델은 SADM을 이용하여 개발하고 임무급 모델은 EADSIM을 이용하여 모델을 개발하였다. 여러 계층의 모델을 연동하기 위해 표준 연동 아키텍처 기반(HLA/RTI)으로 설계하고 구현하였다. 각기 다른 분산된 환경에서 수행되고 있는 시뮬레이션 프로그램들이 상호 연동을 위해 표준 연동 인터페이스 명세에 만족하는 연동 시뮬레이션을 설계하고 각 시뮬레이션 프로그램 간의 중계 역할을 담당하는 통합연동 게이트웨이를 개발하였다. 다해상도 연동 시뮬레이션을 통해 여러 계층 간의 모델을 연동하여 해양 무기체계 효과도 분석을 위한 모델충실도를 향상하고 운용자 필요에 따라 요구되는 전장 환경을 신속하게 구성할 수 있다. 또한 표준연동 아키텍처(HLA/RTI)를 기반으로 설계하게 된 다른 시뮬레이션 프로그램과도 쉽고 효율적으로 연동할 수 있다.

• Nuclear Engineering and Technology
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• 제51권6호
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• pp.1540-1553
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• 2019

A nuclear power plant (NPP) is a highly complex system-of-systems as manifested through its internal systems interdependence. The negative impact of such interdependence was demonstrated through the 2011 Fukushima Daiichi nuclear disaster. As such, there is a critical need for new strategies to overcome the limitations of current risk assessment techniques (e.g. the use of static event and fault tree schemes), particularly through simulation of the nonlinear dynamic feedback mechanisms between the different NPP systems/components. As the first and key step towards developing an integrated NPP dynamic probabilistic risk assessment platform that can account for such feedback mechanisms, the current study adopts a system dynamics simulation approach to model the thermal dynamic processes in: the reactor core; the secondary coolant system; and the pressurized water reactor. The reactor core and secondary coolant system parameters used to develop system dynamics models are based on those of the Palo Verde Nuclear Generating Station. These three system dynamics models are subsequently validated, using results from published work, under different system perturbations including the change in reactivity, the steam valve coefficient, the primary coolant flow, and others. Moving forward, the developed system dynamics models can be integrated with other interacting processes within a NPP to form the basis of a dynamic system-level (systemic) risk assessment tool.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1984-1989
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• 2008

A powered system with fuel cell is regarded as a high current and low voltage source. Effects of the loads on the electrical power source are important to optimize the integrated power system. The design parameters of the system should be chosen by taking into account the characteristics of the fuel cell, so the costs of the power system at given operating conditions can be reduced. Furthermore, the dynamics characteristic of the system is crucial to acquire performance in applications, particularly interactions between loads and the fuel cell system. Currently, no integrated simulation has been approached to analyze interrelated effects. Therefore, the dynamic models of power conversion system with a PEM fuel cell that includes the PEM fuel cell stack, DC/DC converter and associated controls is developed. Electric lads for the system are derived by using a power theory that separates a load current into active, reactive, distortion or a mixed current component. Dependency of the DC capacitor on the loads are analyzed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.463-467
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• 2005

In this paper, the guidance law applicable to formation flight of UAV in three-dimensional space is proposed. The concept of miss distance, which is commonly used in the missile guidance laws, and Lyapunov stability theorem are effectively combined to obtain the guidance commands of the wingmen. The propose guidance law is easily integrated into the existing flight control system because the guidance commands are given in terms of velocity, flight path angle and heading angle to form the prescribed formation. In this guidance law, communication is required between the leader and the wingmen to achieve autonomous formation. The wingmen are only required the current position and velocity information of the leader vehicle. The performance of the proposed guidance law is evaluated using the complete nonlinear 6-DOF aircraft system. This system is integrated with nonlinear aerodynamic and engine characteristics, actuator servo limitations for control surfaces, various stability and control augmentation system, and autopilots. From the nonlinear simulation results, the new guidance law for formation flight shows that the vehicles involved in formation flight are perfectly formed the prescribed formation satisfying the several constraints such as final velocity, flight path angle, and heading angle.