• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.285-288
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• 1998

Ultrasonic signal characteristics related with the growth of electrical trees in epoxy resin are examined under 67[Hz] ac voltage application along with a CCD camera and PD current method. The ultrasonic sensor with a resonant frequency of 200[Hz] supported by a mechanical spring is attached directly to the lower-side of plane electrode. The magnitude of Partial discharge and count rate of ultrasonic signals have been measured according to the tree growth from a needle tip in an epoxy sample.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.595-597
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• 2000

Poymeric insulators using in an heavy contamination area are easily attached to contaminants such as salt and by-products of industrial processes. To understand its effect on contaminants adhered to these insulators, we manufactured slurry mixed by some kaolin and salt as artificial contaminated solution. And then put samples in its slurry, for about one minute. And these samples are dried in natural condition for 6 days. We measured the degree of contaminant, AC leakage current for these contaminated samples.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.476-479
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• 2000

In this study, mesh-type PECVD system was suggested to minimize the hydrogen concentration. The main structural difference between the triode system and a conventional system is that a mesh was attached to the substrate holding electrode. We investigated several conditions to compare with conventional PECVD. The main effect of mesh was to minimize the substrate damage by ion bombardment and to enhance the surface reaction to induce hydrogen desorption. It was also found that hydrogen concentration decreased but deposition rate increased as increasing applied dias. Applied DC bias enhanced sputtering process. Intense ion bombardment causes the weakly bonded hydrogen or hydrogen-containing species to leave the growing film and increased adatom mobility. Furthermore, addition of hydrogen gas enhance the surface diffusion of adatom. The structural properties of poly-Si films were analyzed by scanning electron microscopy(SEM).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.492-493
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• 2007

Organic field-effect transistors (OFETs) are of interest for use in widely area electronic applications. We fabricated a copper phthalocyanine(CuPc) based field-effect transistor with different metal electrode. So we need the effect of the substituent group attached to the phthalocyanine on the surface potential was investigated by Kelvin probe method with varying temperature of the substrate. We were obtained the positive shift of the surface potential for CuPc thin film. We observed the electron displacement at the interface between Au electrode and CuPc layer and we were confirmed by the surface potential measurement.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.170-171
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• 2005

Generally when Power MOSFET is operated, a heat sink is attached to it to emit heat caused by the operation. As the surface area of a heat sink is smaller, the thermal impedance is larger, which causes a negative influence on the characteristics of the chips and the devices and shortens the lifespan of them. In this experiment, we've compared and analysed different effects of heat sinks with 5 different surface areas on the characteristics of Thermal Transient when they are applied respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.85-86
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• 2005

In case of attaching thermoelectric module and heat source, the polymer sheet is attached on the $Al_2O_3$ plate, which is cooling side of thermoelectric module, in order to enhance mechanical safety of the system. It is impossible to calculate the exact distribution of temperature and flow pattern of inner gap of thermoelectric module. Therefore CFD analyses was executed to determine the thermo-fluid phenomena and distribution by Fluent. As the result of these analyses, heat transfer was dominated by conduction and the difference of temperature was linear distribution according to the thickness of polymer sheet.

• Journal of Ocean Engineering and Technology
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• v.27 no.6
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• pp.112-118
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• 2013

This paper reports the results of a comparative study on rudder performance between the steel rudders that have been used in coastal angling fishing boats in the 20-GT class and the newly developed FRP composite material rudders. In order to compare the rudder performances of these two types, a sea trial test was carried out to investigate the speed performance, fuel consumption, and ship's turning ability. The results showed that the sea trial performance of the FRP composite rudder was better than that of the steel rudder type in terms of the sea speed, fuel consumption rate, and turning ability.

• Journal of Yeungnam Medical Science
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• v.23 no.1
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• pp.108-112
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• 2006

The frequency of a bladder foreign body in the female is lower than in the male, and bladder stones attached to foreign bodies such as non-absorbable suture material are not common. Moreover, vesicovaginal fistulas due to migration or puncture of suture materials into the bladder are rare. In this report, we present a case of bladder stone and vesicovaginal fistula formation in a 29-year-old female patient who had been treated with the McDonald operation for an incompetent internal os of the cervix (IIOC) during pregnancy. The patient was successfully treated by cystoscopic removal of the bladder stone with suture material and conservative treatment for the vesicovaginal fistula.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4393-4411
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• 2022

In recent years, beryllium oxide has been widely utilized in multiple compact nuclear reactors as the neutron moderator, the neutron reflector or the matrix material with dispersed nuclear fuels due to its prominent properties. In the past 70 years, beryllium oxide has been studied extensively, but rarely been systematically organized. This article provides a systematic review of the application history, thermal properties, mechanical properties, corrosion behavior and fabrication methods of beryllium oxide. Data from previous literature are extracted and sorted out, and all of these original data are attached as the supplementary material, so that subsequent researchers can utilize this paper as a database for beryllium oxide research in reactor design or simulation analysis, etc. In addition, this review article also attempts to point out the insufficiency of research on beryllium oxide, and the possible key research areas about beryllium oxide in the future.

• Clean Technology
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• v.19 no.3
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• pp.243-248
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• 2013

Thermally conductive materials are widely used in various applications where effective heat dissipation is required. Graphene shows high potential for various uses owing to high electrical conductivity, good mechanical strength, and high thermal conductivity. Generally previous works used organic solvents are generally used for the dispersion of graphene in fabrication procedure. In order to achieve clean fabrication it is required to use water media. In this study, we fabricated graphene attached poly(methyl methacrylate) (PMMA) microsphere via microfluidic method. With the aid of surfactant, graphene was well dispersed in water which was used as continuous flow. Thermal conductivity was improved with the small amount of graphene addition and this indicate potential use of this system for thermally conductive composite material.