• Journal of the Optical Society of Korea
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• v.11 no.3
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• pp.133-137
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• 2007

We compare electroabsorption modulators (EAMs) with multiple quantum wells (MQWs) based on InGaAs(P)/InP and InGa(Al)As/InAlAs material systems. We carefully choose the quantum-well structures so that the structures based on different material systems have similar band-offset energies and excition-peak wavelengths. Assuming the same light wavelength of $1.55{\mu}m$, we show the transfer functions of EAMs with each quantum-well structure and calculate the escape times of photogenerated charge carriers. As the heavy-hole escape time of the quantum well based on InGaAs(P)/InP is much longer than those of photogenerated charge carriers of InGa(Al)As/InAlAs, the EAM based on the InGa(Al)As/InAlAs material seems to be more suitable for high-optical-power operation.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.197-199
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• 2004

In this paper, we studied a accuracy for CT using elastic epoxy. According to industry development, the quality where also the electric material is various is demanded. Insulation material is widely used because epoxy is superior to electrical and mechanical property. Until now, the possibility where the crack will occur is high because epoxy used to electrical products had high hardness. If thermal expansion is different of two material, contraction of epoxy heavily transformed turns ratio of CT. Elastic epoxy absorbed in expansion and contraction of substance material by temperature. So we could design more exacted CT. We had elastic test of elastic epoxy and made CT using elastic epoxy. At the result, We obtained turns ratio of within 4% superior to existing CT.

• Journal of the Korean Ceramic Society
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• v.45 no.2
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• pp.132-137
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• 2008

The main purpose of this study is enhancing the filtering efficiency, performance and durability of filter by growing SiC whiskers on cordierite honeycomb substrate. The experiment was performed by Chemical Vapor Infiltration (CVI) in order to control pore morphology of substrate. Increasing the mechanical strength of porous substrate is one of important issues. The formation of "networking structure" in the pore of porous substrate increased mechanical strength. The high pressure gas injection to the specimen showed that a little of whiskers were separated from substrate but additional film coating enhanced the stability of whisker at high pressure gas injection. Particle trap test was performed. More nano-particle was trapped by whisker growth at the pore of substrate. Therefore it is expected that the porous cordierite which deposited the SiC whisker will be the promising material for the application as filter trapping the nano-particles.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.101-102
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• 2005

SiC lateral power semiconductor device has high breakdown voltage and low on-state voltage drop due to the material characteristics. And, because the high breakdown voltage can be obtained, RESURF technique is mostly used in silicon power semiconductor devices. In this paper, we presents the electrical characteristics of the 4H-SiC RESURF LDMOSFET as a function of the epi-layer length, concentration and thickness. 240~780V of breakdown voltage can be obtained as a function of epi-layer length and thickness with same epi-layer concentration.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.812-813
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• 2011

This paper presents the characteristic of newly developed electrical steel and motor performance analysis for HEV/EV. This material is developed and optimized for high frequency operation to reduce the core losses in traction motors to increase fuel efficiency. Four types of electrical steel are introduced, which are optimized for high flux density (PNHF), high frequency low core loss (PNF), high punchability (PNS) and high strength (PNT) to meet different specifications from different types of traction motors. To identify the motor performance with this material, finite element analysis was used to calculate core loss as well as Ld and Lq for efficiency map. Also structure analysis was performed to calculate stress on bridge rotor.

• Nuclear Engineering and Technology
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• v.44 no.1
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• pp.89-102
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• 2012

The buffer and backfill are important components of the engineered barrier system in a high-level waste repository, which should be constructed in a hard rock formation at a depth of several hundred meters below the ground surface. The primary function of the buffer and backfill is to seal the underground excavation as a preferred flow path for radionuclide migration from the deposited high-level waste. This study investigates the hydraulic conductivity and swelling pressure of Kyungju Ca-bentonite, which is the candidate material for the buffer and backfill in the Korean reference high-level waste disposal system. The factors that influence the hydraulic conductivity and swelling pressure of the buffer and backfill are analyzed. The factors considered are the dry density, the temperature, the sand content, the salinity and the organic carbon content. The possibility of deterioration in the sealing performance of the buffer and backfill is also assessed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.499-499
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• 2008

High voltage transformer of Diagnostic X-ray system has been contributed to wiping out disease to get a good quality images from patients. High voltage transformer of diagnostic X-ray system has been usefully used for diagnostic purpose but if high voltage transformer performances are deteriorated, low quality image will be archived. In this case, operator has to exposure to get a more good quality images. In this case, unexpected radiation could be exposed to patient and it is very harmful to the patient. And I would like to design and make equipment to checkable high voltage transformer performance after that I wish to test and study what it is most influences in radiation output quality.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.140-141
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• 2006

Background doping concentration (BDC) is proven to be a critical factor to affect the high current behavior of the extended drain NMOSFET (EDNMOS) devices. The EDNMOS device with low BDC suffers from strong snapback in the high current region, which results in poor electrostatic discharge (ESD) protection performance and high latchup risk. However, the strong snapback can be avoided in the EDNMOS device with high BDC. This implies that both the good ESD protection performance and the latchup immunity can be realized in terms of the EDNMOS by properly controlling its BDC.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.559-560
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• 2006

Inkjet Printing is very attractive method for direct patterns with no masks, In order to Achieve direct printing with nano metal, It is often necessary to print them with highly concentrated Ink We research the High Concentrated silver nano ink. Formulation which has a good thermal stability and storage stability and jet stability using a ethylene glycol ether. Normally Alcohol-based inks can be sensitive But High boiling point ethylene glycol ether base Ink is creating a stable meniscus and minimum maintenance issues. We are reaching a 50~60wt% high Silver Ink using a Hydrophilic Ag Nano powder. (30~50nm)

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.149-150
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• 2005

According to the trend for electric power equipment of high capacity and reduction of its size, the needs for the new high performance electric equipments become more and more important. On of the possible solution is high temperature superconducting (HTS) power application. Following the successful development of practical HTS wires, there have been renewed activities in developing superconducting power equipment. HTS equipments have to be operated in a coolant such as liquid nitrogen ($LN_2$) or cooled by conduction-cooling method such as using Gifford-McMahon (G-M) cryocooler to maintain the temperature below critical level. In this paper, the dielectric strength of unfilled epoxy and filled epoxy in $LN_2$ was analyzed. The filled epoxy composite not only compensates for this fragile property but enhances its dielectric strength.