• Journal of Advanced Navigation Technology
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• v.17 no.6
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• pp.693-699
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• 2013

In this paper, ${\pi}/4$-DQPSK modem according to ITU-R M.1842-1 recommendation Annex1 is investigated and simulated. At first, standardization and technical trend of VHF maritime mobile communication are introduced. The ${\pi}/4$-DQPSK modem defined in the Annex1 should support 28.8Kbps bit transmission rate within 25KHz frequency bandwidth. We describe the system model and simulation process of ${\pi}/4$-DQPSK modem transmitter and receiver design with RRC(Root Raised Cosine) transmitter and receiver filter. Then we suggest various graphical simulation results(time domain signals, constellation, power spectral density according to roll-off factor, eye diagram), and show simulated BER performance of the modem. From the simulation results, it is shown that roll-off factor of RRC filter affects to BER performance according to SNR and the designed simulation model meets the spectrum mask requirement suggested in ITU-R M.1842-1 recommendation.

• Journal of Korean Society of Disaster and Security
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• v.16 no.1
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• pp.61-70
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• 2023

This study presents an analytical study of investigating the effect of shock waves generated by the hydrogen detonation and damage to structures for the safety evaluation of hydrogen storage facilities against detonation. Blast scenarios were established considering the volume of the hydrogen storage facility of 10 L to 50,000 L, states of charge (SOC) of 50% and 100%, and initial pressures of 50 MPa and 100 MPa. The equivalent TNT weight for hydrgen detonation was determined considering the mechanical and chemical energies of hydrogen. A hydrogen detonation model for the converted equivalent TNT weight was made using design equations that improved the Kingery-Bulmash design chart of UFC 3-340-02. The hydrogen detonation model was validated for overpressure and impulse in comparison to the past experimental results associated with the detonation of hydrogen tank. A parametric study based on the blast scenarios was performed using the validated hydrogen detonation model, and design charts for overpressure and impulse according to the standoff distance from the center of charge was provided. Further, design charts of the three-stage structural damage and standoff distance of adjacent structures according to the level of overpressure and impact were proposed using the overpressure and impulse charts and pressure-impulse diagrams.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.2
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• pp.212-218
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• 2007

This paper presents a implementation of speed sensorless vector control of induction motor using MATLAB/SIMULINK and dSPACE DS1104. Proposed flux estimation algorithm, which utilize the combination of the voltage model based on stator equivalent model and the current model based on rotor equivalent model, enables stable estimation of rotor flux. Proposed rotor speed estimation algorithm utilizes the estimated flux. And the estimated rotor speed is used to speed control of induction motor. Overall system consists of speed controller, current controller, and flux controller using the most general PI controller. Speed sensorless vector control algorithm is implemented as block diagrams using MATLAB/SIMULINK. And realtime control is performed by dSPACE DS1104 control board and Real-Time-Interface(RTI).

• The Journal of Korean Institute of Information Technology
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• v.16 no.12
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• pp.31-40
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• 2018

We designed and implemented the attachable smart adapter for the general management of each company's agricultural machine regardless of whether it is equipped with a CAN (Controller Area Network) module. The smart adapter consists of a main board (Raspberry Pi3B), which operates agricultural machine's management software in Linux environment, and a self-developed interface board for power adjustment and status sensing. For the status monitoring, a sensing interface using a serial input was defined between the smart adapter and the sensors of the agricultural machine, and the state diagram of the agricultural machine was defined for diagnosis. We made a panel to simulate the sensors of the agricultural machine using the switch's on/off contact point, and confirmed the status monitoring and diagnostic functions by inputting each state of the farm machinery from the simulator panel.