• ETRI Journal
• /
• v.30 no.2
• /
• pp.249-254
• /
• 2008

In this paper, we demonstrate an electrically band-limited carrier-suppressed return-to-zero (EB-CSRZ) signal generator operating up to a 10 Gbps data rate comprising a single-stage Mach-Zehnder modulator and a wideband signal mixer. The wideband signal mixer comprises inverter stages, a mixing stage, and a gain amplifier. It is implemented by using a 0.13 ${\mu}m$ CMOS technology. Its transmission response shows a frequency range from DC to 6.4 GHz, and the isolation response between data and clock signals is about 21 dB at 6.4 GHz. Experimental results show optical spectral narrowing due to incorporating an electrical band-limiting filter and some waveform distortion due to bandwidth limitation by the filter. At 10 Gbps transmission, the chromatic dispersion tolerance of the EB-CSRZ signal is better than that of NRZ-modulated signal in single-mode fiber.

• Proceedings of the KIEE Conference
• /
• 2003.04a
• /
• pp.412-414
• /
• 2003

Communication based train control system is applied regularly worldwide. And this system may be used in domestic soon. Communication based train control system does not depend on conventional track circuit. Therefore, position and distance control of train to prevent collision with leading train may become important safety factor. This paper developed collision avoidance algorithm to control trains of several units efficiently for this. In developing a collision avoidance algorithm, it is desirable to avoid the need for additional system. Additional system restricts the development of the algorithm by limiting the effectiveness of the algorithm to only those areas where the additional system can be afforded and has been installed.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.706-707
• /
• 2011

The insertion of the crowbar system in the doubly fed induction generator rotor circuit for a short period of time during grid disturbance enables a more efficient way of limiting transient rotor current and hence protecting the rotor side converter (RSC) and the DC - link capacitor. When crowbar is activated at fault occurrence and clearance time, RSC is blocked while DC -link capacitor and the grid side converter (GSC) can be controlled to provide reactive power support at the PCC and improve the voltage which helps to comply with grid codes. In this paper, control strategies for crowbar system to limit the rotor current during fault is presented with RSC and GSC controllers are modified to control PCC voltage during disturbance to enhance DFIG wind farm to comply with some strict grid codes. Model simulated on MATLAB/Simulink verify the study through simulation results presented.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.21 no.12
• /
• pp.1111-1117
• /
• 2008

A transformer type superconducting fault current limiter (SFCL) is one of the fault current limiters which have been proposed to reduce the fault current in the transmission lines. This paper proposes the new circuit configuration of a transformer type SFCL and also investigates the operating characteristics of the transformer type SFCL containig the resistor in the tertiary winding. The proposed SFCL contains the resistor in the tertiary winding. The newly inserted resistor can divert the power which the High-Tc superconducting has to bear. Because the resistor in the tertiary winding relieves the power of the High-Tc superconducting, it is possible that the proposed transformer type SFCL can decrease the more larger fault current than the conventional SFCL with the same High-Tc superconducting. And the cost of the proposed transformer type SFCL can be reduced.

• Proceedings of the KIEE Conference
• /
• 1992.07b
• /
• pp.762-764
• /
• 1992

This Paper presents some experimental result of current limiting and short circuit interruption behavior of thin copper film, 12${\mu}m$, 25${\mu}m$, 40${\mu}m$, 50${\mu}m$ on alumina substrate. and a fuse-link having elements of copper film provided with high-precision small hols with electrolytical process. Construction, fabrication, as well as the test circuitry built especially for the develoment of this fuse-links are explained below.

• Proceedings of the KIEE Conference
• /
• 1992.07b
• /
• pp.1176-1178
• /
• 1992

This paper shows enhanced working performance of the battery fork-lift truck by developing the IGBT full bridge dc-dc convertor using one-chip micro-processor. The PWM pulse is generated from a 16 bit one-chip micro-processor for the speed control of DC motor. In order to ensure the operation of IGBT and motor pecewisely, IGBT gate drive circuit was designed by using current limiting IC and hige voltage limit IC. And also It is able to regenerative braking.

• Proceedings of the KSR Conference
• /
• 2004.06a
• /
• pp.1349-1352
• /
• 2004

Communication based train control system is applied regularly worldwide. And this system may be used in domestic soon. Communication based train control system does not depend on conventional track circuit. Therefore, position and distance control of train to prevent collision with leading train may become important safety factor. This paper developed collision avoidance algorithm to control trains of several units efficiently for this. In developing a collision avoidance algorithm, it is desirable to avoid the need for additional system. Additional system restricts the development of the algorithm by limiting the effectiveness of the algorithm to only those areas where the additional system can be afforded and has been installed.

• Journal of the Optical Society of Korea
• /
• v.12 no.1
• /
• pp.49-51
• /
• 2008

The wide-band spiral inductor to be monolithically integrated on the AlN substrate as a choking inductor for a compact 10 Gb/s optical transmitter applications is investigated. In order to reduce the parasitic capacitance limiting the choking bandwidth, the AlN substrate is partially etched away, which is analyzed by using an equivalent circuit model. The measured $S_{21}$ transmission response of the fabricated inductor is suppressed as low as -10 dB in the frequency range of 5 to 16 GHz.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 1999.02a
• /
• pp.101-105
• /
• 1999

We have performed an EMTDC simulation for the current limiting effects of a superconducting fault current limiter (SFCL). The fault currents in the 154 kV transmission line between the Gaepo and Sungnam substations increased up to 54kA and 60kA during the line-to-line and three phase faults, respectively. The SFCL with 100 $\Omega$ of impedance after quench limited the currents to less than 17 kA within a half cycle. This limited current is well below the upper limit of a circuit breaker, suggesting that the impedance of the SFCL in the transmission line is sufficient.

• Progress in Superconductivity
• /
• v.5 no.2
• /
• pp.136-140
• /
• 2004

We fabricated and tested a resistive superconducting fault current limiters (SFCL) operated at 3.8 ㎸ based on YBCO thin films. The SFCL was composed of 7 components connected in series. Each component was designed to be capable of current limiting at 600 V, and has a SiC shunt resistor ( $R_{s}$) of 40 Ω in Parallel. Short circuit tests were carried out fur 0 and 90 degree faults lasting fur 5 cycles. The test results showed that the 7 components were quenched simultaneously under the safe quenches and evenly shared the applied voltage. The SFCL successfully suppressed the fault currents below 94 $A_{peak}$ within the quarter cycle after fault.t.t.