• The Transactions of the Korean Institute of Power Electronics
• /
• v.20 no.3
• /
• pp.209-213
• /
• 2015

With the increasing popularity of renewable generation systems and the advancement of power electronics, DC distribution systems have recently received considerable research attention. DC distribution has numerous advantages, including reliability, power quality, and efficiency. Owing to these advantages, DC distribution has been applied to data centers and power quality-sensitive electronic load conditions. Because grounding electrodes in DC are much more susceptible to corrosion than in AC, the IT system defined in IEC Standard 60364 may be a good candidate for an earthing method for DC distribution systems. In addition, IEC Standard 61557 specifies the requirements for insulation monitoring devices (IMD) for protection of the IT system, which continuously monitors the insulation resistances between the power lines and the earth. This paper discusses the development and evaluation of IMD to promote the reliability of distribution systems and increase safety of humans and facilities.

• Proceedings of the KIEE Conference
• /
• 1989.11a
• /
• pp.231-234
• /
• 1989

In recent, due to the advanced development of the power semiconductor devices, the Digital Simulation becomes essential in order to investigate the behavior of the system before the manufacturing of the system by using computer for design and analysis of Power Electronic systems. This paper develope the program so-called PECA, which can be applied for the Power Electronic circuits composing of power transistors, thyristers, GTOs and power FET, etc. We consider transistor DC chopper circuit and prove the effectiveness of our program by both the experiment and simulation.

• Transactions on Electrical and Electronic Materials
• /
• v.5 no.4
• /
• pp.129-132
• /
• 2004

The electrothermal characteristics of a high voltage LIGBT(Lateral Insulated Gate Bipolar Transistor) using thin silicon on insulator (SOI) and silicon on sapphire (SOS) such as thermal conductivity and sink is analyzed by MEDICI. The device simulations demonstrate that the thermal conductivity of the buried oxide is an important parameter for modeling of the thermal behavior of SOI devices. In this paper we simulated the thermal conductivity and temperature distribution of a SOI LIGBT with an insulator layer of SiO$_2$ and $Al_2$O$_3$ at before and after latch-up and verified that the SOI LIGBT with the $Al_2$O$_3$ insulator had good thermal conductivity and reliability.

• Proceedings of the KIEE Conference
• /
• 2001.11c
• /
• pp.352-355
• /
• 2001

In this paper, we proposed measurement error reduction technique for the semiconductor device DC characteristic measurement system. Implemented system is composed of 4 SMUs, 2 VSUs, and 2 VMUs. Various efforts in hardware and software have been made to reduce the measurement errors due to the leakage current in measurement circuits. Internal and external sources of errors in measurement system especially in pA range measurement have been identified and removed. Experimental results show that the implemented system can be measure the DC characteristic of semiconductor devices in pA level.

• Proceedings of the KIEE Conference
• /
• 1999.07c
• /
• pp.1136-1138
• /
• 1999

This paper describes a new method of the modeling of protection system and fault diagnosis in power systems using Petri nets. The Petri net models of protection system are compose of the operating process of protective devices and the fault diagnosis process. Fault diagnosis model which makes use of the nature of Petri net is developed to overcome the drawbacks of methods that depend on operator knowledge. The proposed method can reduce processing time and increase accuracy when compared with the traditional methods. And also this method covers online processing of real-time data from SCADA.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07b
• /
• pp.1002-1006
• /
• 2004

The studies on OLED(Organic Light-Emitting Diode) materials and structures have been researched in other to improve luminescence efficiency of OLED. Electrons and holes are injected into the devices, transported across the layer and recombine to form excitons, their profiles are sensitive to mobility velocity of electrons and holes. A suggested means of improving the efficiency of LEDs would be to balance the injection of electrons and holes into light emission layer of the device. In this paper, we demonstrate the difference of velocity between hole and electron by experiments, and compare with a data of simulation and experiment changing hole carrier transport layer thickness, so we get the optimal we improve luminescence efficiency. We improve understanding of the various luminescence efficiency through experiments and numerical analysis of luminescence efficiency in the hole carrier transport layer's thicknes.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.348-348
• /
• 2010

Nanostructures have great potential in various devices due to the their promising electronic and optical properties. Nano-patterned the front surface of a solar cell generally results in improved performance, mostly due to an increase in the short-circuit current by the incident photons strike the cell surface at an angle. In this work, we investigate AFM-assisted nano-patterned field effect transistors (FETs) with vairous silicon oxide distance value D, from ${\sim}0.5{\mu}m$ to $1{\mu}m$. Also, we compared the electro-optical characteristics of the patterned FETs and the non-patterned FETs (reference device) based on both 2-dimensional simulation and experimental results for the wavelength from 100nm to 900nm. In addition, we report electric characteristics for illuminated surface in schottky barrier field effect transistors (SB-FETs).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.33-34
• /
• 2008

Barium titanate (BaTiO3) is one of the most important dielectric materials for the electronic devices, such as MLCC (Multilayer Ceramic Capacitor). The thickness of the dielectric thin film in MLCC has become thinner and reached about 0.8 ${\mu}m$. Further down sizing is required for the higher performance. For this reason, we should take into account for the size effect of Barium titanate powders. In this study, we demonstrated that size effect for BaTiO3 (0.2 ~ 0.5 ${\mu}m$, hydrothermal BT) could be estimates by using dielectric properties analysis together with the powder properties.

• Journal of electromagnetic engineering and science
• /
• v.9 no.2
• /
• pp.53-60
• /
• 2009

Remarkable developments in the electric and electronic industry have given people's daily life much more convenience and abundance. However, in electrical communication, or electric and electronic fields, making electrical and electronic devices more functional, more integrated, and faster have put electromagnetic interference(EMI) into more complex forms, and lots of problems such as interruption, malfunction, or interference by noise between electrical communication systems occurs every day. In this research, the electromagnetic compatibility(EMC) filter in the high powered breaker was designed and fabricated as a counter measure. The filter attenuated noise more than 20${\sim}$50 dB in the range of 10 MHz${\sim}$1.5 GHz. And, when the electric fast transient(EFT) of 4 kV in the level 4 of IEC 61000-4-4 was induced, it was soon suppressed to 600 V.

• Transactions on Electrical and Electronic Materials
• /
• v.8 no.5
• /
• pp.211-214
• /
• 2007

Chemical and morphological changes of phenol formaldehyde-based photoresist after $O_2$ radiofrequency(RF) plasma treatment depending on exposure time and source power were investigated. It was found that etch rate of photoresist sharply increased after discharge turn on and reached a limit with increase in plasma exposure time. Contact angle measurements and X-ray photoelectron spectroscopy(XPS) analysis showed that the surface chemical structure become nearly constant after 15 sec of the treatment. Atomic force microprobe(AFM) measurements were shown that surface roughness was increased with plasma exposure time.