• Proceedings of the KSR Conference
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• 2005.11a
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• pp.643-648
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• 2005

Headlight monitoring is one of the new requirement in the modern Metro EMU design. In order to meet this requirement. several kinds methods are already provided in the train. This paper introduces another method. which is designed with the darlington circuit and can switch off/on the headlight with the circuit. Following the conceptual method. the monitoring module was developed and installed in domestic line. Investigation of the concept shall be focused on the more smaller module and expending the module to other part.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.12
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• pp.1640-1648
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• 2014

This paper proposes a switching frequency reduction method for MMC (Modular Multilevel Converter) utilizing redundancy operation of sub-module, which can offer reduction of voltage harmonics and switching loss. The feasibility of proposed method was verified through computer simulations with PSCAD/EMTDC software. Based on simulation analysis, a hardware scaled-model of 10kVA, DC-1000V MMC was designed and manufactured in the lab. Various experiments were conducted to verify the feasibility of proposed method in the actual hardware system. The hardware scaled-model can be effectively utilized for analyzing the performance of MMC according to the modulation scheme and redundancy operation.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.10
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• pp.77-83
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• 2010

In this paper, the noise of HEV(hybrid electric vehicle)-relay module during the turn-on and turnoff switching is experimentally analyzed and an effective method is proposed to reduce the impact noise. First, enclosure methods of 100A relay part with urethane and silicon are tested to find out a better material to isolate the noise. This result shows that the urethane is a better for the noise isolation of relay, so the relays enclosed by urethane are installed in the relay module. Second, the noise of HEV-relay module is analyzed experimentally to identify the noise generation mechanism. From this result, it is found that the vibration transmitted to battery pack through bolt generates the structural borne noise with the frequency band of 200~2000 Hz, which is more serious when the switch is turned off. Finally, the direction of switching and the joint structure are modified in order to isolate the vibration transmitted to battery back. Both methods are very effective to reduce the switching noise.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.7
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• pp.3433-3446
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• 2019

Aiming at the high complexity of traditional single-channel demodulation algorithm for PCMA signals, a new demodulation algorithm based on neural network is proposed to reduce the complexity of demodulation in the system of non-cooperative PCMA communication. The demodulation network is trained in this paper, which combines the preprocessing module and decision module. Firstly, the preprocessing module is used to estimate the initial parameters, and the auxiliary signals are obtained by using the information of frequency offset estimation. Then, the time-frequency characteristic data of auxiliary signals are obtained, which is taken as the input data of the neural network to be trained. Finally, the decision module is used to output the demodulated bit sequence. Compared with traditional single-channel demodulation algorithms, the proposed algorithm does not need to go through all the possible values of transmit symbol pairs, which greatly reduces the complexity of demodulation. The simulation results show that the trained neural network can greatly extract the time-frequency characteristics of PCMA signals. The performance of the proposed algorithm is similar to that of PSP algorithm, but the complexity of demodulation can be greatly reduced through the proposed algorithm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.710-713
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• 2004

The design, simulation, modeling and measurement of a low temperature co-fired ceramic (LTCC) RF switch module for GSM applications is presented in this paper. RF switch module is constructed using a Rx/Tx switching circuit and integrated low pass filter. The low pass filter function was designed to operate in th GSM band. Insertion and return loss of the low pass filter were designed less than 0.3 dB and better than 12.7 dB at 900 MHz. The RF switch module contained 10 embedded passives and 3 surface mount components integrated on $4.6{\times}4.8{\times}1.2$ nm, 6-layer multi-layer integrated circuit. The insertion loss of switch module was measured at 900 MHz was 11 dB.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.536-537
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• 2012

In this paper, current-fed soft switching push-pull converter for Photovoltaic AC module was proposed. The theoretical analysis of the proposed converter is verified by simulation and experiment.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.3
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• pp.21-30
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• 2018

Driven by the recent energy saving trend, conventional silicon based power conversion modules are being replaced by modules using silicon carbide. Previous papers have focused mainly on the electrical advantages of silicon carbide semiconductors that can be used to design switching devices with much lower losses than conventional silicon based devices. However, no systematic study of their thermomechanical reliability in power conversion modules using finite element method (FEM) simulation has been presented. In this paper, silicon and silicon carbide based power devices with three-phase switching were designed and compared from the viewpoint of thermomechanical reliability. The switching loss of power conversion module was measured by the switching loss evaluation system and measured switching loss data was used for the thermal FEM simulation. Temperature and stress/strain distributions were analyzed. Finally, a thermal fatigue simulation was conducted to analyze the creep phenomenon of the joining materials. It was shown that at the working frequency of 20 kHz, the maximum temperature and stress of the power conversion module with SiC chips were reduced by 56% and 47%, respectively, compared with Si chips. In addition, the creep equivalent strain of joining material in SiC chip was reduced by 53% after thermal cycle, compared with the joining material in Si chip.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2597-2600
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• 1999

Semiconductor devices can be series stacked for the application of high voltage switching. It can provide high reliability and long lifetime by the safe design with a reasonable margin. The equal voltage distribution at solid-state switches in series should be guaranteed. Static and dynamic voltage division, over current protection must be considered carefully in the design stage. A fast switching thyristor is a good candidate for the high power pulse applications. A high voltage switching module is designed and tested. Its specifications are working voltage of 70 kV, switching pulse width of 120${\mu}s$, peak switching current of 220A, maximum repetition rate of 200pps. The module can be series connected to get higher working voltage. This paper presents the design details and the test results are compared with expected circuit simulations.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.2B no.3
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• pp.115-124
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• 2002

This paper presents an active auxiliary edge-resonant DC link snubber with a ringing surge damper and a three-phase voltage source type zero voltage soft-switching inverter with the resonat snubber treated here for the AC servo motor driver applications. The operation of the active auxiliary edge-resonant DC link snubber circuit with PWM voltage is described, together with the practical design method to select its circuit parameters. The three-phase voltage source type soft-switching inverter with a single edge-resonant DC link snubber treated here is evaluated and discussed for the small-scale permanent magnet (PM) type-AC servo motor driver from an experimental point of view. In addition to these, the AC motor stator current and its motor speed response for the proposed three-phase soft-switching inverter employing Intelligent Power Module(IPM) based on IGBTS are compared with those of the conventional three-phase hard-switching inverter using IPM. The practical effectiveness of the three-phase soft-switching inverter-fed permanent magnet type AC motor speed tracking servo driver is proven on the basis of the common mode current in a novel type three-phase soft-switching inverter-fed AC motor side and the conductive noise on the mains terminal interface voltage as compared with those of the conventional three-phase hard-switching inverter-fed permanent magnet type AC servo motor driver for the speed tracking applications.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.6
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• pp.183-190
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• 2004

This paper proposes a methodology to solve problems upon the circuit design applied to inductor load by applying a circuit to improve power factor with is partial switching PFC module to the power supply system for cooling/heating inverter air conditioner and by designing an input power section in compliance with IEC555-2 on the basis of better input power factor and minimized harmonic components of current. On the other hand, this paper suggested how to control the increase of output voltage along with tぉw current waves and partial switching PFC circuit as well, which can provide the output as twice as input voltage This study applied a method to control the compressors of air conditioner by means of increased the voltage applicable to compressor motor by lowering switching number conclusively, it could solve questions about efficiency, economics, electronic noise and so forth. and so that the reasonable voltage for running moor could be set up along with lower power consumption of air conditioner than estimated It was demonstrated that total sum of energy efficiency to operate system was increased to the extent of valid level. And all this merits and appropriateness was proved by computer simulation and experience.