• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.05c
• /
• pp.257-260
• /
• 2003

In this study, the structural, dielectric and piezielectric properities of $xPb(Mg_{1/3}Nb_{2/3})O_3-(0.5-x)Pb(Ni_{1/3}Nb_{2/3})O_3-0.5Pb(Zr_{0.3}Ti_{0.7})O_3$ ceramics were investigated with the substitution of $PbMg_{1/3}Nb_{2/3}O_3$. The results showed that the substitution of the $PbMg_{1/3}Nb_{2/3}O_3$ was effective in increasing the dielectric constant and electromechanical coupling factor $(K_p)$. The dielectric constant, dielectric loss and Kp showed the highest values of 4293, 2.4%, 0.59 relatively, when the substitution of amount of $PbMg_{1/3}Nb_{2/3}O_3$ was 5 mol%.

• Journal of Biosystems Engineering
• /
• v.24 no.2
• /
• pp.123-134
• /
• 1999

The electrical properties such as dielectric constant, dielectric loss factor and AC conductivity of grain were presented to measure the moisture content of grain using RF impedance. At frequency ranging from 1 to 10MHz and room temperature, $20^{\circ}C$, vector network analyzer(HP4195) and coaxial type sample holder were used to analyze the electrical properties of paddy(11∼24%w.b.), brown rice(11∼18%w.b.), barley(11∼21%w.b.) and wheat(11∼23%w.b.) depending on the moisture content, frequency and bulk density. The dielectric constant and AC conductivity of grain samples increased with moisture content and bulk density. The dielectric constants decreased with frequency and could be expressed as function of the moisture density(decimal moisture $content{\times}bulk$ density).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.1
• /
• pp.43-47
• /
• 2001

Plasma polymerized hexamethyldisiloxane thin film was fabricated by employing an inter-electrode capacitively coupled type apparatus under the following conditions : carrier gas flow rate of 11 sccm, reaction pressure of 0.1 torr, discharge frequency of 13.56 MHz and discharge power of 30∼90 W. Polymerization rate of thin film fabricated at the discharge power of 90W is 32.5nm/min. Relative dielectric constant and dielectric loss tangent of thin film shows 3.2∼3.8 and 2.6x10$\^$-3/∼4.51x10$\^$-3/ respectively in the frequency range of 1 kHz∼1 MHz. As the annealing temperature is increased, the relative dielectric constant gradually decreases while the dielectric loss tangent increases. The current density increase gradually with increasing annealing temperature and electric field. The electric conduction of the heaxamethyldisiloxane thin film shows Schottky effect.

• Journal of the Semiconductor & Display Technology
• /
• v.4 no.1 s.10
• /
• pp.55-59
• /
• 2005

The ($Sr_{1-x}Ca_{x})Ti_{3}$(SCT) thin film are deposited on Pt-coated electrode (Pt/TiN/$SiO_{2}$/Si) using RF sputtering method. The maximum dielectric constant of SCT thin film is obtained by annealing at 600[$^{\circ}C$]. The temperature properties of the dielectric loss have a value within 0.02 in temperature lunges of -80 $\∼$ +90[$^{\circ}C$]). The capacitance characteristics had a stable value within ${\pm}4\%$. The drastic decrease of dielectric constant and increase of dielectric loss in SCT thin films is observed above 200[kHz).

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.543-546
• /
• 2003

We studied the dielectric layer effect on the electro-optical (EO) properties of liquid crystal (LC) devices together with numerical simulations. Recently, it has been reported that the surface dielectric layer affects significantly the EO performances of LC microlens arrays and wide-viewing LC displays. it is found that the operation voltage of the LC device decreases with increasing the dielectric constant or with decreasing the thickness of the dielectric polymer layer. The experimental data agree well with theoretical results predicted in a simple dielectric model within the continuum formalism.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1996.05a
• /
• pp.206-210
• /
• 1996

In order to investigate the electrical properties for transformer oils which contains a Pure sodium chloride, the dielectric properties is made researches. To measure the dielectric loss of specimen, a coaxial cylindrical liquid electrode is used, and its geometric capacitance is confirmed to 16[pF]. And the dielectric dissipation factor, tan$\delta$, is measured by using the Video Bridge 2150. The thermal static oven with an automatically static temperature controller is used so as to support specific temperature to the specimen. This experiments for measuring the dielectric lass is performed at 20-120[$^{\circ}C$] in the temperature range, 30∼1.5x10$\^$5/[Hz] in the frequency range and 300∼1500[mV] in the voltage range. The result of experiment for the movement of carrier and the physical constants to contribute dielectric properties of specimen with a pure sodium chloride.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.18 no.11
• /
• pp.1038-1042
• /
• 2005

We have investigated dielectric properties depending on bias voltage in organic light-emitting diodes using 8-hydroxyquinoline aluminum $(Alq_3)$ as an electron transport and emissive material. We analyzed the dielectric properties of organic light-emitting diodes using impedance of characteristics. Impedance characteristics was measured complex impedance Z and phase $\theta$ in the frequency range of 40 Hz to $10^8$ Hz. We obtained complex electrical conductivity, dielectric constant, and loss tangent $(tan\delta)$ of the device at room temperature. From these analyses, we are able to interpret a conduction mechanism and dielectric properties contributed by an interfacial and orientational polarization.

• Transactions on Electrical and Electronic Materials
• /
• v.13 no.6
• /
• pp.322-325
• /
• 2012

Crystalline silica was synthesized by annealing amorphous silica at $1,300^{\circ}C$ or $1,400^{\circ}C$ for various times, and the crystallinity was estimated by X-ray diffraction (XRD) analysis. In order to prepare a low dielectric material, epoxy/crystalline silica composites were prepared, and the effect of silica content on the dielectric properties was studied under various functions of frequency and ambient temperature. The dielectric constant decreased with increasing crystalline silica content in the epoxy composites, and it also decreased with increasing frequency. At 120 Hz, the value of 5 wt% silica decreased by 0.25 compared to that of 40 wt% silica, and at 23 kHz, the value of 5 wt% silica decreased by 0.23 compared to that of 40 wt% silica. The value increased with increasing ambient temperature.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.51 no.9
• /
• pp.413-416
• /
• 2002

It was reported that low temperature plasma developed by our group was apparently homogeneous and stable at atmospheric pressure, and was generated if the alumina was used as a dielectric insulating material and Ar gas as a plasma gas. This is a structure in which the dielectric materials are covered and arranged in parallel in the one side of electrode. In this experiment, we discovered that dielectric material was important to generate normal electric discharge. To examine the effect of dielectric material on the electric discharge characteristic, the voltage and current of the plasma was measured and the electrical effect of dielectric material was examined. Also, it was applied to an etching of tin oxide films.

• Proceedings of the KSME Conference
• /
• 2001.06c
• /
• pp.64-70
• /
• 2001

This work deals with the electrical conductivity of dielectric and cobalt percentage on output parameters such as metal removal rate and surface roughness value of sintered carbides cut by wire-electrical discharge machining (W-EDM). To obtain a precise workpiece with good quality, some extra repetitive finish cuts along the rough cutting contour are necessary. Experimental results show that increases of cobalt amount in carbides affects the metal removal rate and worsens the surface quality as a greater quantity of solidified metal deposits on the eroded surface. Lower electrical conductivity of the dielectric results in a higher metal removal rate as the gap between wire electrode and workpiece reduced. Especially, the surface characteristics of rough-cut workpiece and wire electrode were analyzed too. To obtain a good surface equality without cracks, 4 finish-cuts were necessary by reducing the electrical energy and the offset value.