• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1422-1424
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• 1998

This paper deals with the surface aging and electrical characteristics of EPDM specimen with cooling and heating cycle. Then dielectric loss and weight loss are measered to evaluate electrical properties of EPDM on bulk and surface The specimens which underwent aging cycle over 600 hr reveal severe erosion on EPDM surface

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2315-2317
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• 2005

In this paper, an iterative method to model the electromagnetic heating of electrically large lossy dielectrics is presented. Frequency domain finite element (FEM) solutions of the wave equation are determined for the lossy inhomogeneous dielectric as the material properties are change with temperature and time. The power absorbed from microwave losses is applied to a finite element time domain (FETD) calculation of the heat diffusion equation. Time steps appropriate for updating the piecewise material properties in the wave equation and the time stepping of the heat equation are presented. The effects of preheating and source frequency are investigated.

• Journal of the Korean Ceramic Society
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• v.37 no.4
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• pp.295-301
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• 2000

The effect of V2O5 addition on the low temperature sintering of Pb(Mn1/3Sb2/3)O3-PZT ceramics, which is known as a prominent material for piezoelectric transformer application was studied, and the densification behavior and piezoelectric characteristics of the samples as a function of heating rate were also examined. V2O5 led the system to liquid phase sintering by forming liquid phase during sintering, which accelerated densification through the particle rearrangement in the early stage of sintering. The liquid phase mostly existed at grain boundaries retarded the evaporation of PbO, while the densification temperature and the weight loss of V2O5-free samples were higher than those of samples with V2O5. Faster heating improved the densification of the samples regardless of V2O5 addition. The low temperature sintering at 100$0^{\circ}C$ was achieved in PMS-PZT ceramics with high density and reasonable dielectric and piezoelectric characteristics. This result revealed optimistic way to the development of multi-layered piezoelectric transformers.

• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.283-286
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• 2001

For the common drier and heaters, the heat gradually transfers from exterior to interior in the materials, as it generally adopts radiant or/and convection heat. However, by using microwave, both the interior and exterior of fiber materials can be evenly heated simultaneously. (omitted)

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.278.1-278.1
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• 2014

Organic materials have been explored as the gate dielectric layers in thin film transistors (TFTs) of backplane devices for flexible display because of their inherent mechanical flexibility. However, those materials possess some disadvantages like low dielectric constant and thermal resistance, which might lead to high power consumption and instability. On the other hand, inorganic gate dielectrics show high dielectric constant despite their brittle property. In order to maintain advantages of both materials, it is essential to develop the alternative materials. In this work, we manufactured nanocomposite gate dielectrics composed of organic material and inorganic nanoparticle and integrated them into organic TFTs. For synthesis of nanocomposite gate dielectrics, polyimide (PI) was explored as the organic materials due to its superior thermal stability. Candidate nanoprticles (NPs) of halfnium oxide, titanium oxide and aluminium oxide were considered. In order to realize NP concentration dependent electrical characteristics, furthermore, we have synthesized the different types of nanocomposite gate dielectrics with varying ratio of each inorganic NPs. To analyze gate dielectric properties like the capacitance, metal-Insulator-metal (MIM) structures were prepared together with organic TFTs. The output and transfer characteristics of organic TFTs were monitored by using the semiconductor parameter analyzer (HP4145B), and capacitance and leakage current of MIM structures were measured by the LCR meter (B1500, Agilent). Effects of mechanical cyclic bending of 200,000 times and thermally heating at $400^{\circ}C$ for 1 hour were investigated to analyze mechanical and thermal stability of nanocomposite gate dielectrics. The results will be discussed in detail.

• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1216-1221
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• 1999

GaN films were deposited on sapphire [$Al_2O_3(0001)$] substrates at relatively low temperature by MOCVD using N-atom source based on a Dielectric Barrier Discharged method. Ammonia gas($NH_3$is commonly used as an N-source to grow GaN films in conventional MOCVD process, and heating to high temperature is required to provide sufficient dissociation of $NH_3$. We used a dielectric barrier discharge method instead of $NH_3$ to grow GaN film relatively low temperature. DBD is a type of discharge, which have at least one dielectric material as a barrier between electrode. DBD is a type of controlled microarc that can be operated at relatively high gas pressure. Crystallinity and surface morphology depend on growth temperature and buffer layer growth. With the DBD-MOCVD method, wurtzite GaN which is dominated by the (0001) reflection was successfully grown on sapphire substrate even at $700^{\circ}C$.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.7
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• pp.514-520
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• 1999

Ferroelectric PZT(30/70)/PZT(70/30) heterolayered thin films were fabricated by spin-coating method on the $Pt/Ti/SiO_2Si$ substrate alternately using(30/70) and PZT(70/30) alkoxide solutions prepared by sol-coating method. The coating and heating procedure was repeated six times to form PZT heterolayered films, and thickness of the film obtained by one-times drying/sintering process was about 40-50 nm. All PZT heterolayered films, showed dense and homogeneous structure without the presence of rosette sturctrue. The relative dielectric constant, remanent polarization and leakage current density of PZT heterolayered films were superior to those of single composition PZT(30/70) and PZT(70/30) films, and those values for the PZT-6 film were 975, $21 \muC/cm^2\; and\; 8\times10^{-9}\; A/cm^2$, respectively. And the PZT-6 heterolayered film showed fairly good fatigue characteristics of remanent polarization and coercive field after application of $10^8$ switching cycles.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.11
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• pp.35-43
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• 1995

To obtain high quality of $Ta_{2}O_{5}$ film, two dielectric layers of $Si_{3}N_{4}$ and $Ta_{2}O_{5}$ were subsequently formed on Si wafer. Silicon nitride films were thermally grown in 10 Torr ammonia ambient by R.F induced heating system. The thickness of thermally grown $Si_{3}N_{4}$ film was able to be controlled in the range of tens $\AA$ due to the self-limited growth property. $Ta_{2}O_{5}$ film of 200$\AA$ thickness was then deposited on the as-grown $Si_{3}N_{4}$ film about 25$\AA$ thickness by sputtering method and annealed at $900^{\circ}C$in $O_{2}$ ambient for 1hr. Stoichiometry film was prepared by the annealing in oxygen ambient. Despite the high temperature anneal process, silicon oxide layer was not grown at the interface of the layered films because of the oxidation barrier effect of Si$_{3}$N$_{4}$ film. The fabricated $Ta_{2}O_{5}$/$Si_{3}N_{4}$ film showed low leakage current less than several nA and high dielectric breakdown strength.

• Korean Journal of Food Science and Technology
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• v.18 no.5
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• pp.329-333
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• 1986

Rice bran ell was blended with double fractionated palm olein (DF palm olein) to examine the cooking performance of blended oil. A blended oil made with 80% or higher rice bran oil and 20% or less DF palm olein passed the cold test, and had a cloud point of $-3^{\circ}C$. Blending of DF palm olein to rice bran oil lowered the smoke point, refractive index, and absorbancies at 232 and 268 nm of rice bran oil. Dielectric constant of oils was not affected by blending during heating. Blending of DF palm olein , however, increased the acids formation in rice bran oil, whereas it retarded polymer formation. The results of the analytical methods used in this study except dielectric constant measurement showed significant difference among the blended oils depending on the blending ratios.

• Journal of the Korean Ceramic Society
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• v.43 no.3 s.286
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• pp.173-176
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• 2006

${Sr_{1-x}Ba_xNb_2O_6$(SBN) have been obtained in Pt crucible by melting and cooling in air atmosphere. Some SBNs being at the bottom of the crucible are black and transparent, and the other SBNs colorless. The black SBN became to be colorless by oxidation heat treatment $1,300^{\circ}C$ for 4 h, Curie temperature is changed by colorless change of black SBN. The reason seems to be $Nb^{5+}$ oxidation of some $Nb^{4+}$ ions in SBN or effect of unknown impurities. Diffused Phase Transition (DPT) was appeared during heating and cooling process. Various sintered SBN ceramics specimen showed relaxor characteristics.