• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08a
• /
• pp.727-729
• /
• 2007

Inorganic-organic hybrid polymer provides various advantages including low-temperature process, high dielectric constant and direct photo-patterning. The hybrid dielectric was synthesized by the sol-gel process in which an acid-catalyzed solution of Si alkoxide and Zr alkoxide was used as a precursor. The electrical performance of transistors with hybrid dielectric was investigated.

• The Korean Journal of Ceramics
• /
• v.2 no.2
• /
• pp.111-113
• /
• 1996

Dielectric properties at microwave frequency region of the five-layered compound $Ba_5Nb_4O_{15}$ prepared by the conventional solid state reaction method were investigated. $Ba_5Nb_4O_{15}$ has excellent microwave dielectric characteristics; ${\varepsilon}_r$=38, Q=7500 at 10 GHz, and ${\tau}_l$=+50 ppm/K. Since this compound has a high dielectric constant, high Q and sufficiently stable characteristics, it is useful for the applications at microwave frequencies.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.63 no.4
• /
• pp.301-306
• /
• 2014

Recently in accordance with the rapid development of the industrial society, the accidents caused by dielectric breakdown have been increasing in power grid. It is important to prevent the dielectric breakdown of a high voltage apparatus to reduce the damage from electrical hazards. To establish an electrically reliable database of insulation design criteria for high voltage apparatus, a study on dielectric characteristics test is indispensable. In this study, dielectric characteristics according to field utilization factors (${\xi}$) which are represented as the ratio of mean electric field to maximum electric field are investigated. the dielectric breakdown experiments by using several kinds of electrode systems made with stainless steel are performed by AC breakdown voltage under air-insulation. Also, the experimental results are analyzed by the Weibull distribution. As a result, it is found that the dielectric characteristics of air-insulation are determined by ${\xi}$ as well as arrangement of electrode systems. It is considered that the results of this study would be applicable to designing the air-insulated high voltage apparatuses.

• Macromolecular Research
• /
• v.15 no.2
• /
• pp.114-128
• /
• 2007

Polyimides are one of the most important classes of polymers used in the microelectronics and photoelectronics industries. Because of their high thermal stability, chemical resistance, and good mechanical and electric properties, polyimides are often applied in photoresists, passivation and dielectric films, soft print circuit boards, and alignment films within displays. Recently, fully aliphatic and alicyclic polyimides have found applications as optoelectronics and inter layer dielectric materials, due to their good transparencies and low dielectric constants $(\varepsilon)$. The low molecular density, polarity and rare probability of forming inter- or intra-molecular charge transfers, resulting in lowering of the dielectric constant and high transparency, are the most striking characteristics of aliphatic polyimide. However, the ultimate end use of polyimides derived from aliphatic monomers is in their targeted applications that need less stringent thermal requirements. Much research effort has been exerted in the development of aliphatic polyimide with increased thermal and mechanical stabilities, while maintaining their transparencies and low dielectric constants, by the incorporation of rigid moieties. In this article, the recent research process in synthesizing fully aliphatic polyimides, with improved dimensional stability, high transparency and low $\delta$values, as well as the characterizations and future scope for their application in micro electric and photo-electronic industries, is reviewed.

• Journal of the Korean Ceramic Society
• /
• v.40 no.4
• /
• pp.350-353
• /
• 2003

Millimeter-wave dielectric ceramics have been used like applications for ultrahigh speed wireless LAN because it reduces the resources of electromagnetic wave, and Intelligent Transport System (ITS) because of straight propagation wave. For millimeterwave, the dielectric ceramics with high quality factor (Q$.$f), low dielectric constant($\varepsilon$), and nearly zero temperature coefficient of resonant frequency ($\tau$) are needed. No microwave dielectric ceramics with these three properties exist except Ba(Mg$\_$1/3/Ta/sub1/3/)O$_3$ (BMT), which has a little high s: In this paper, alumina (Al$_2$O$_3$) and fosterite (Mg$_2$SiO$_4$), candidates for millimeter-wave applications, were studied with an objective to get high q$.$f and nearly zero $\tau$$\_$f/ For alumina ceramics, q$.$f more than 680,000 GHz was obtained but it was difficult to obtain nearly zero Qf. On the other hand, for forsterite ceramics, q$.$f was achieved from 10,000 GHz of commercial for sterite to 240,000 GHz of highly purified MgO and SiO$_2$ raw materials, and $\tau$$\_$f/ was reduced a few by adding TiO$_2$ with high positive $\tau$$\_$f/.

• Transactions on Electrical and Electronic Materials
• /
• v.16 no.2
• /
• pp.53-61
• /
• 2015

High-energy ball milling was tested as a method for producing Ultra High Molecular Weight Polyethylene (UHMWPE)- based nanodielectrics containing 1 wt% and 5 wt% OctaIsoButylPOSS (OibPOSS). Qualitative and quantitative evaluations were used to explore the compatibility between OibPOSS and PE. Several ball milling variables were optimized in a bid to achieve UHMWPE/OibPOSS nanodielectrics. The morphology, as well as the thermal and the dielectric properties of the samples, were characterized by scanning electron microscopy, thermogravimetric analysis, broadband dielectric spectroscopy, and progressive-stress breakdown tests. The results showed that (i) ball milling was an effective method for producing UHMWPE/OibPOSS dielectric composites, but appeared ineffective in dispersing OibPOSS at the nanoscale, and (ii) the resulting UHMWPE/OibPOSS dielectric composites presented thermal and dielectric properties similar to those of neat UHMWPE.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2000.01a
• /
• pp.181-182
• /
• 2000

The glass compositions of $PbO-SiO_2-B_2O_3$ system and $P_2O_5-PbO-ZnO$ system for the transparent dielectric materials for front panel and $P_2O_5-ZnO-BaO$ and $SiO_2-ZnO-B_2O_3$ for the reflective dielectric materials for back panel of PDP(Plasma Display Panel) were investigated. As a transparent dielectric materials for front panel, $PbO-SiO_2-B_2O_3$ glass showed good dielectric properties, high transparency and proper thermal expansion matching to soda-lime glass substrate. And the reflective dielectric materials for back panel were prepared from parent glass of $SiO_2-ZnO-B_2O_3$ system and oxide filler. It was found that these glass-ceramics are useful materials for reflective dielectric layers, as those have a similar thermal expansion to soda-lime glass plate, high reflectance, low sintering temperature.

• Proceedings of the Polymer Society of Korea Conference
• /
• 2006.10a
• /
• pp.168-168
• /
• 2006

Low-operating voltage organic field-effect transistors (OFETs) have been realized with high dielectric constant (${\kappa}$) polymer such as cyanoethylated poly vinyl alcohol (CR-V, ${\kappa}=12$). Since the $high-{\kappa}$polymers are likely to contain water and ionic impurities, large hysteresis and considerable leakage current are frequently observed in OFETs. To solve these problems, we cross-linked the CR-V by using a cross-linking agent. Cross-linked CR-V dielectrics showed high dielectric constant of 11.1 and good insulating properties, resulting in a high capacitance ($81nF/cm^{2}$ at 1MHz) at 120 nm of dielectric thickness. Pentacene FETs with cross-linked CR-V dielectrics exhibited high carrier mobility ($0.72\;cm^{2}/Vs$), small subthreshold swing (185 mV/dec) and little hysteresis at low-operating voltage (${\Leq}-3V$).

• Korean Journal of Food Science and Technology
• /
• v.28 no.3
• /
• pp.470-474
• /
• 1996

The dielectric properties, dielectric constant (${\varepsilon}‘$) and loss factor (${\varepsilon}’$), of skin and pulp of fresh ginseng were measured from $25^{\circ}C$ to $67^{\circ}C$ using an open-ended coaxial probe technique for 915 MHz and 2450 MHz. Pulp and skin had dielectric constant of $30{\sim}64$ and loss factor between 10 and 20, each variable having a respective frequency dependence typical of materials with high water content. Although the loss factor was nearly constant, the dielectric constant increased as moisture content increased. The dielectric constant of ginseng pulp increased as temperature increased (temperature ${\leq}56^{\circ}C$), but any significant differences were not found in skin dielectric properties. Penetration depth for fresh ginseng were about 2 cm at 91.5 MHz and 1cm at 2450 MHz.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.826-828
• /
• 2003

With a new PDP transparent dielectric layer formation technique, we were able to make dielectric layer with high transmittance by using dry film type dielectric material. We optimized dielectric pastes for dry film and they showed good process properties in lamination , drying and firing.