• Proceedings of the KIEE Conference
• /
• 1993.07b
• /
• pp.749-752
• /
• 1993

This paper deals with the development of three phase 440[V], 500[KVA] Inverter system using the IGBT Devices. IGBT's have been used very successfully in variable frequency induction motor drive equipment. Problems associated with power devices characteristics when power devices are operated in parallel, such as balanced switching behavior and thermal stability, can be solved by using NPT type IGBT's. By Experimental results, it is confirmed that the voltage overshoot and reverse recovery current was very low. The equipment had proved to be reliable and short circuit proof. In addition, the performances in term of thermal characteristics, protection functions and stability are satisfactory.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.9
• /
• pp.1079-1086
• /
• 2012

In this paper, X-band 60 W Solid-State Power Amplifier with sequential control circuit and pulse width variation circuit for improve bias of SSPA module was designed. The sequential control circuit operate in regular sequence drain bias switching of GaAs FET. The distortion and efficiency of output signals due to SSPA nonlinear degradation is increased by making operate in regular sequence the drain bias wider than that of RF input signals pulse width if only input signal using pulsed width variation. The GaAs FETs are used for the 60 W SSPA module which is consists of 3-stage modules, pre-amplifier stage, driver-amplifier stage and main-power amplifier stage. The main power amplifier stage is implemented with the power combiner, as a balanced amplifier structure, to obtain the power greater than 60 W. The designed SSPA modules has 50 dB gain, pulse period 1 msec, pulse width 100 us, 10 % duty cycle and 60 watts output power in the frequency range of 9.2~9.6 GHz and it can be applied to solid-state pulse compression radar using pulse SSPA.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.26 no.7
• /
• pp.613-619
• /
• 2015

In this paper, we proposed a paper-based pattern-switchable antenna using inkjet-printing technology. The proposed antenna is composed of two bow-tie antennas and a switching network. The bow-tie antennas are inkjet-printed on paper using a low cost home printer. The switching network is built on a printed-circuit-board(PCB) and consists of a single-pole-double-throw(SPDT) switch and balun element. A double-sided parallel-strip line(DSPSL) can convert the unbalanced microstrip mode to the balanced strip mode. Two bow-tie antennas have different radiation patterns because of the different orientation of the reflectors. It is demonstrated from EM simulation and measurement that the radiation patterns of the proposed antenna are successfully switched by the SPDT.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.19 no.6
• /
• pp.140-147
• /
• 2011

The injection nozzle of an electro-hydraulic injector for the common rail Diesel fuel injection system is being opened and closed by movement of a injector's needle which is balanced by pressure at the nozzle seat and at the needle control chamber, at the opposite end of the needle. In this study, the slenoid actuator was considered as a prime movers in high pressure Diesel injector. Namely a solenoid-driven Diesel injector with different driving current types, as a general method driven by solenoid coil energy, has been applied with a purpose to develop the analysis model of the solenoid actuator to predict the dynamics characteristics of the hydraulic component (injector) by using the AMESim code. Aimed at simulating the hydraulic behavior of the solenoid-driven injector, the circuit model has been developed as a unified approach to mechanical modeling in this study. As this analytic results, we know the suction force and first order time lag for driving force can be endowed in solenoid-driven injector in controlling the injection rate. Also it can predict that the input current wave exerted on solenoid coil is the dominant factor which affects on the initial needle behavior of solenoid-driven injector than the hydraulic force generated by the constant injection pressure.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 1999.11a
• /
• pp.161-166
• /
• 1999

The global trends of mobile communication system is moving toward digitizing, high-speed and large-capacity. Also, to utilize the limited frequency-resource efficiently, spread spectrum system is a mainstream. In this study we are concerning with the fast frequency-hopping system. Instead of the PLL with many problems such as phase-noise, we used the DDS is popular in these days minimizes the disadvantage of PLL. In the case the FFH system is designed using the PLL, it is difficult to be satisfied of the design conditions such as RF badwidth and the settling time of PLL, and it has limitation because of complex circuit by using the balanced modulator. In this study, we evaluated the performance in order to design the FFH system using the DDS. The system that has the improvement of error rate, 1Mhps hopping rate and 5MHz RF bandwidth is designed and evaluated.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.16 no.3
• /
• pp.283-292
• /
• 2011

This paper proposed a new multi-level inverter topology based on a H-bridge with two switches and two diodes connected to the DC-link. The output voltage of the proposed topology is quite closer to a sinusoidal waveform compared with a typical single phase inverter. The proposed multi-level inverter is applicable to a power conditioning system for renewable energy sources, and it can be also used as a building block of a cascaded multi-level inverter for a high voltage application. In case of conventional H-bridge type or NPC type multi-level inverter, 8 controllable switches are used to obtain a 5 level output voltage, but the proposed multi-level inverter requires only 6 controllable switches. Thus the circuit configuration is quite simple, reliable and cost-effective implementation is possible. The efficiency can be improved owing to the reduction of the switching loss. A new PWM method based on POD modulation is suggested which requires only one carrier signal. The switching sequence to make the capacitor voltage balanced is also considered. The feasibility is studied through simulation and experiment.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.49 no.8
• /
• pp.22-26
• /
• 2012

This paper introduces a 2.5-Gb/s optical receiver implemented in a standard 1P4M 0.18um CMOS technology for the applications of active optical HDMI cables. The optical receiver consists of a differential transimpedance amplifier(TIA), a five-stage differential limiting amplifier(LA), and an output buffer. The TIA exploits the inverter input configuration with a resistive feedback for low noise and power consumption. It is cascaded by an additional differential amplifier and a DC-balanced buffer to facilitate the following LA design. The LA consists of five gain cells, an output buffer, and an offset cancellation circuit. The proposed optical receiver demonstrates $91dB{\Omega}$ transimpedance gain, 1.55 GHz bandwidth even with the large photodiode capacitance of 320 fF, 16 pA/sqrt(Hz) average noise current spectral density within the bandwidth (corresponding to the optical sensitivity of -21.6 dBm for $10^{-12}$ BER), and 40 mW power dissipation from a single 1.8-V supply. Test chips occupy the area of $1.35{\times}2.46mm^2$ including pads. The optically measured eye-diagrams confirms wide and clear eye-openings for 2.5-Gb/s operations.