• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.2
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• pp.142-149
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• 2004

This paper presents a neural network controller of a grid-connected wind energy conversion system for extracting maximum power from wind and a power controller to transfer the maximum power extracted into a utility grid. It discusses the modeling and simulation of the wind energy conversion system with the controllers, which consists of an induction generator, a transformer, a link of a rectifier, and an inverter. The paper describes tile drive train model, induction generator model and grid-interface model for dynamics analysis. Maximum power extraction is achieved by controlling the pitch angle of the rotor blades by a neural network controller. Pitch control method is mechanically complicated, but the control performance is better than that of the stall regulation. The simulation results performed on MATLAB show the variation of the generator torque, the generator rotor speed, the pitch angle, and real/reactive power injected into the grid, etc. Based on the simulation results, the effectiveness of the proposed controllers is verified.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.4
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• pp.73-80
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• 2010

The grounding impedance is not lowered by expanding the dimension of the grounding electrode, and the length of grounding electrode which shows the minimum value of the grounding impedance for each condition of frequency and soil characteristics is existent, and it is defined as Critical Length. In this paper, a new distributed parameter circuit model considering the condition of the multi-layered soil structures was proposed, and the grounding impedance and critical length of the vertical grounding electrode were analyzed by using the newly proposed simulation model and the MATLAB program. As a consequence, it was found that the effect of the soil structure on the frequency-dependent grounding impedance and critical length of the vertical grounding electrode is significant. It is desirable to consider the soil structure in optimal design of the grounding system.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.1
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• pp.70-79
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• 2013

In this work, a steady-state performance modeling and off-design performance analysis of the 2-spool separate-flow turbofan engine named (BR715-56) which is a power plant for the narrow body commercial aircraft is carried out for engine performance behaviors investigation and condition monitoring using a commercial code MATLAB/SIMULINK. Firstly, the engine component maps of fan, high pressure compressor, high pressure turbine and low pressure turbine are generated from similar component maps using the scaling method, and then the off-design performance simulation model is constructed by the mass flow matching and the work matching between components. The model is developed using SIMULINK, which has advantages of easy steady-stare and dynamic modelling and user friendly interface function. It is found that the off-design performance analysis results using the proposed model are well agreed with the performance analysis results by GASTURB at various operating conditions.

• Journal of Advanced Navigation Technology
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• v.19 no.4
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• pp.288-298
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• 2015

For the commercialization of unmanned aircraft, we must validate the safety of the air/ground collision alert systems (CAS). The validation procedure of CAS requires the flight test which is not only expensive but also dangerous. To alleviate this problem, we need the simulation based validation process for the CAS. We developed an integrated UAV simulation (IUS) environment which interconnect the flight simulator, the Matlab/Simulink, and a target avionics simulation model. We developed the collision warning module of the TCAS and tested using IUS and flight encounter models. Using IUS, we can evaluate the performance and reliability of a target avionic system at the preliminary design stage of a development life cycle.

• Journal of the Korea Convergence Society
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• v.3 no.4
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• pp.35-44
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• 2012

In this study, a simulation program is developed in order to investigate non steady-state cornering performance of 6WD/6WS special-purpose vehicles. 6WD vehicles are believed to have good performance on off-the-road maneuvering and to have fail-safe capabilities. But the cornering performances of 6WS vehicles are not well understood in the related literature. In this paper, 6WD/6WS vehicles are modeled as a 18 DOF system which includes non-linear vehicle dynamics, tire models, and kinematic effects. Then the vehicle model is constructed into a simulation program using the MATLAB/SIMULINK so that input/output and vehicle parameters can be changed easily with the modulated approach. Cornering performance of the 6WS vehicle is analyzed for brake steering and pivoting, respectively. Simulation results show that cornering performance depends on the middle-wheel steering as well as front/rear wheel steering. In addition, a new 6WS control law is proposed in order to minimize the sideslip angle. Lane change simulation results demonstrate the advantage of 6WS vehicles with the proposed control law.

• Journal of the Korea Convergence Society
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• v.8 no.4
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• pp.9-18
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• 2017

UAVs began to be actively applied to so-called 3D jobs, including the autonomous exploration, investigation, mapping, search and rescue, etc. since the mid-2000s. With this global trend, having a precise controllability of the UAV will certainly revolutionize the life of the modern human in the aspect of tremendous applications of the UAV. In the first part, a simplified dynamic model of the UAV identified using system identification techniques is compared with the previously built time-discrete linear model. In the second part, the three parameters of the dynamic model are estimated using the batch and RLS methods. Angular acceleration data of the quadrotor UAV at the hovering maneuver are analyzed and shown to be converging at all time. Also, according to the quadrotor flight data from both experiments and MATLAB simulations, the batch estimation method turns out to be more accurate than the RLS estimation method based on the comparison of final parameter values.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1C
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• pp.90-97
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• 2009

The advantages of the orthogonal frequency division multiplexing (OFDM) are high spectral efficiency, resiliency to RF interference, and lower multi-path distortion. To further utilize vast channel capacity of the multiuser OFDM, one has to find the efficient adaptive subchannel and bit allocation among users. In this paper, we propose an 0-1 integer programming model formulating the optimal subchannel and bit allocation problem of the multiuser OFDM. We employ a dual-decomposition method that provides a tight linear programming (LP) relaxation bound. Simulation results are provided to show the effectiveness of the 0-1 integer programming model. MATLAB simulation on a system employing M-ary quardarature amplitude modulation (MQAM) assuming a frequency-selective channel consisting of three independent Rayleigh multi-paths are carried with the optimal subchannel and bit allocation solution generated by 0-1 integer programming model.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.219-224
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• 2012

In this work, a steady-state performance modeling and off-design performance analysis of the 2-spool separate jet turbofan engine named BR715-56 which is a power plant for the narrow body commercial aircraft is carried out for engine performance behaviors investigation and condition monitoring using a commercial code MATLAB/SIMULINK. Firstly, the engine component maps of fan, high pressure compressor, high pressure turbine and low pressure turbine are generated from similar component maps using the scaling method, and then the off-design performance simulation model is constructed by the mass flow matching and the work matching between components. The model is developed using SIMULINK, which has advantages of easy steady-stare and dynamic modelling and user friendly interface function. It is found that the off-design performance analysis results using the proposed model are well agreed with the performance analysis results by GASTURB at various operating conditions.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.2
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• pp.247-254
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• 2021

Problems such as a limited frequency resource and interference between adjacent bands have been continuously raised because of rapidly developing wireless technology and communication service. In order to solve that problem, government has been developed and operating the Spectrum Management Intelligent System(SMIS). This paper compares the results simulated by SMIS with the ATDI and the Matlab coded provided by ITU-R for verification of SMIS operating for the public interests. The Recommendation ITU-R P.526, P.1546, and P.1812 among the propagation model loaded in SMIS were chosen because of the relation to the broadcasting service. The comparison and analysis result shows that the outputs derived by SMIS has the small error of less than 1 dB. This research could be utilized for the policy establishment and R&D for the frequency allocation and the interference between adjacent bands.

• Earthquakes and Structures
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• v.22 no.1
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• pp.1-13
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• 2022

When a building suffers damages under moderate to severe loading condition, its physical properties such as damping and stiffness parameters will change. There are different practical methods besides various numerical procedures that have successfully detected a range of these changes. Almost all the previous proposed methods used to work with translational components of mode shapes, probably because extracting these components is more common in vibrational tests. This study set out to investigate the influence of using both rotational and translational components of mode shapes, in detecting damages in 3-D steel structures elements. Three different sets of measured components of mode shapes are examined: translational, rotational, and also rotational/translational components in all joints. In order to validate our assumptions two different steel frames with three damage scenarios are considered. An iterative model updating program is developed in the MATLAB software that uses the OpenSees as its finite element analysis engine. Extensive analysis shows that employing rotational components results in more precise prediction of damage location and its intensity. Since measuring rotational components of mode shapes still is not very convenient, modal dynamic expansion technique is applied to generate rotational components from measured translational ones. The findings indicated that the developed model updating program is really efficient in damage detection even with generated data and considering noise effects. Moreover, methods which use rotational components of mode shapes can predict damage's location and its intensity more precisely than the ones which only work with translational data.