• The Journal of the Acoustical Society of Korea
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• v.37 no.6
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• pp.451-456
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• 2018

UAComm (Underwater Acoustic Communication) is an active research area, and many experiment has been performed to develop UAComm system. In this paper, we investigate the possibility of modifying and applying VirTEX (Virtual Time series EXperiment) to medium long range MIMO (Multiple-Input Multiple-Output) UAComm of about 20 km range for the analysis and performance prediction of UAComm system. Since VirTEX is a time-domain simulator, the generated time series can be used in HILS (Hardware In the Loop Simulation) to develop UAComm system. The developed package is verified through comparing with the sea-going FAF05 (Focused Acoustic Field 2005) experimental data. The developed simulator can be used to predict the performance of UAComm system, and even replace the expensive sea-going experiment.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1786-1790
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• 2004

The main objective of this paper is to analyze the performance of various force control algorithms in improving and adjusting the compliance of industrial robots in contact with their environment. Some of fundamental force control algorithms such as sensorless control, impedance control and hybrid position/force control are theoretically analyzed and simulated for various situations of an environment, and then a series of experiments using them were performed. In this paper, a control scheme to use position control in implementing the impedance control was investigated in order to nullify the effect of joint friction. The new reference trajectory is generated using contact force feedback and original desired trajectory. And an inner position control loop is designed to provide accurate position tracking for the new reference trajectory and good disturbance rejection. Experiments to insert a peg in a hole (so-called the peg-in-a-hole task) were performed with HILS (hardware-in-theloop simulation) system based on the results of the analyses and simulations on the characteristics of each control algorithm. The experiments showed that various force control methods improved the performance of robots in close contact with the environment by adjusting their compliance with respect to an arbitrary set of coordinates.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2228-2234
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• 2000

Steering of the vehicles on a slippery highway is a difficult task for most passenger car drivers. The steering vehicles on slippery roads tend to slide outward with less lateral forces than on nor mal roads. When the drivers notice that their vehicles on a slippery highway start to depart from the cornering lane, most of them make a sudden steering and/or braking, which in turn may induce spin-out and instability on their vehicles. In this paper, an active steering control method is proposed such that the vehicles in slippery roads are steered as if they are driven on the normal roads. In the proposed method, the estimated lateral forces acting on the steering tires are compared with the reference values and the difference is compensated by the active steering method. A fuzzy logic controller is designed for this purpose and evaluated on a steering Hardware-In-the-Loop Simulation (HILS) system. Steering performance results on the slippery curved and sinus roads demonstrate the effectiveness of the proposed controller. This method can be realized with the steer-by-wire concept and is promising as an active safety technology.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.2
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• pp.185-194
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• 2016

It is essential for generating the synthetic image to test and evaluate a guided missile system in the hardware-in-the-loop simulation. In order to make the evaluation results to be more reliable, the extent of fidelity and rendering performance of the synthetic image cannot be left ignored. There are numerous challenges to simulate the LWIR sensor signature of sea surface depending on the incident angle, especially in the maritime environment. In this paper, we investigate the key factors in determining the apparent temperature of sea surface and propose the approximate formula consisting of optical characteristics of sea surface and sky radiance. We find that the greater the incident angle increases, the larger the reflectivity of sea surface, and the greater the water vapor concentration in atmosphere increases, the larger the amount of sky radiance. On the basis of this information, we generate the virtual maritime environment in LWIR region using the SE-WORKBENCH, physically based rendering software. The margin of error is under seven percentage points.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.2
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• pp.75-81
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• 2021

This study analyzes the resonance characteristics caused by the mutual interference between LCL filters and the grid impedance under the parallel operation of the grid-connected inverter using the LCL filter. These characteristics are verified through simulation and experiment. Two inverters are used to connect to the grid in parallel, and the system parameters, including the LCL filter, are set to the same conditions. In the case of inverters running in parallel at the point of common coupling, the presence of grid impedance causes mutual interference between the LCL filters of each inverter, and the deviation of the filter resonance frequency is analyzed to understand the parallel inverter. The correlation between the number of devices and the size of grid impedance is simulated by PSIM and verified by MATLAB. By connecting the real-time digital simulator Typhoon HILS to the DSP 28377 control board, the mutual interference characteristics are tested under the condition of two inverters running in parallel. The experimental and analysis results are the same, indicating the validity of the analysis.

• Journal of Power Electronics
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• v.19 no.1
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• pp.254-264
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• 2019

This paper proposes an indirect current control technique based on a proportional resonant (PR) approach for the seamless mode transfer of utility interactive inverters. Direct-current and voltage hybrid control methods have been used for inverter control under grid-connected and islanded modes. A large bandwidth can be selected due to the structure of single-loop control. However, this results in poor dynamic transients due to sudden changes of the controller during mode changes. Therefore, inverter control based on indirect current is proposed to improve the dynamic transients by consistently controlling the output voltage under all of the operation modes. A PR-based indirect current control topology is used in this study to maintain the load voltage quality under all of the modes. The design processes of the PR-based triple loop are analyzed in detail while considering the system stability and dynamic transients. The mode transfer techniques are described in detail for both sudden unintentional islanding and islanded mode voltage quality improvements. In addition, they are described using the proposed indirect control structure. The proposed method is verified by the PSiM simulations and laboratory-scale VDER-HILS experiments.

• The Journal of the Acoustical Society of Korea
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• v.13 no.2
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• pp.30-37
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• 1994

Since the morden targets are of high speed and getting quiet in both active and passive mode, the necessities of developing advanced SONAR system capable of performing target motion analysis (TMA) and target classification are evident. In order to develop such a system, the scattering mechanism of complex bodies needs to be, some extent, fully understood and modeled. In this paper, MOving Spread Target(MOST) signal simulation model is presented and discussed. The model is based on the highlight distribution method, and simulates pulse elongation of spread target, doppler effect due to kinematics of the target as well as SONAR platform, and distribution target strength of each highlight point (HL) with directivity. The model can be used in developing and evaluating advanced SONAR system through system simulation, and can also be used in the development of target state estimation algorithm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.219-220
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• 2016

A power management system (PMS) has been an important part in a ship integrated control system. To evaluate a PMS for a liquefied natural gas carrier (LNGC), this research proposes a real-time hardware-in-the-loop simulation (HILS), which is composed of major component models such as turbine generator, diesel generator, governor, circuit breaker, and 3-phase loads on MATLAB/Simulink. In addition, FPGA based control console and main switchboard (MSBD) are constructed in order to develop an efficient control and a similar real environment in an LNGC PMS. A comparative study on the performance evaluation of PMS functions is conducted using two test cases for sharing electric power to consumers in an LNGC. The result shows that the proposed system has a high verification capability for the operating function and failure insertion evaluation as a PMS simulator.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.621-626
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• 2019

The driver's steering wheel maneuver is a typical disturbance that causes excessive body motion and traveling instability of a vehicle. Abrupt and extreme operation can cause rollover depending on the geometric and dynamic characteristics, e.g., SUV vehicles. In this study, to cope with the performance limitation of conventional cars, fundamental research on the structurization of a control system was performed as follows. Mathematical modeling of the lateral behavior induced by driver input was carried out. A controller was designed to reduce the body motion based on this model. An algorithm was applied to secure robust control performance against modeling errors due to parameter uncertainty, $H_{\infty}$. Using the decoupled 1/4 car, a dynamic load simulating model considering the body moment was suggested. The simulation result showed the validity of the load-simulating model. The framework for a lateral behavior control system is proposed, including an experimental 1/4 vehicle unit, load simulating module, suspension control module, and hardware-in-the-loop simulation technology.

• The Journal of Korean Institute for Practical Engineering Education
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• v.3 no.2
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• pp.75-82
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• 2011

Recently the technology of green growth became more important role among the problems of running out of fossil fuels and global warming. To procure a new growth power combined with energy and green growth, a lot of investment for wind power, photovoltaics system, fuel cell and biofuel expanded day by day. Among these, wing power has a merit of a highly economic and no discharge of toxic substance. These days government and industrial companies actively support the development of wind power technology with lots of investment, but domestic related education and equipment still stay in research level when it is compared with foreign advanced countries which lead the wind power technology. Therefore to expand the base of basic skill required in the related industrials and to advance technology, we are in the situation to be needed a development of a new curriculum and educational equipment which is analogous with the actual industrial system. In this paper a development of a new educational equipment for the learning of turbine control is introduced. This educational equipment has been developed for students to get easy understanding for the theory of wind turbine control. And finally to demonstrate the effect of the use of the developed equipments and curriculum a questionnaire carried out.