• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.08a
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• pp.109-122
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• 2002

The standard capacitor must have not only precise value of the capacitance but also the basic properties of low dielectric loss tangent. In the reforming process of capacitors, the dielectric loss tangent must be also reformed. In this paper, the development of standard capacitors of 10 and 100pF for the dielectric loss tangent standard using $Al_{2}O_{3}$ Crystal and the measurement of dielectric loss tangent are discussed. The dielectric loss tangent depends upon the surface between electrode and dielectric in capacitor. With using the Electric Field Simulator, precise design values of electrode are simulated. For the purpose of measuring capacitance effect just in the dielectric, 3-Terminal and 4-Terminal Pair configuration are applied respectively at the electrode and the connector for the measuring equipment. As stated above method, the standard capacitors of 10 and l00pF for the establishment of the dielectric loss tangent standard using the $Al_{2}O_{3}$ Crystal are made with low dielectric loss tangent less than 10-4.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1466-1468
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• 1996

The standards of the capacitance arc measured and analyzed by the dry nitrogen or mica film as a dielectric. In this paper, respectively the standard capacitors of 10 pF and 100 pF for the establishment of the dielectric loss tangent are made by $Al_{2}O_{3}$ crystal disc with the low dielectric loss tangent, and then measured the dielectric loss tangent with precision. To regard for the existence of capacitances just in the dielectric, 3-terminal configuration electrode is used. With using the 2D electric field simulator, precise design values are derived in addition to stray capacitance. As stated above method, respectively the standards of the capacitances with 10 pF and 100 pF arc made with the low dielectric loss tangent less than $10^{-4}$.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.1
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• pp.73-77
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• 2008

We have investigated dielectric polarization in organic light-emitting diodes using 8-hydroxyquinoline aluminum($Alq_3$) as an electron transport and emissive material. We analyzed the dielectric polarization of organic light-emitting diodes using characteristics of impedance and equivalent circuit of $ITO/Alq_3/Al$. Impedance characteristics was measured complex impedance Z and phase ${\theta}$ in the frequency range of $1{\times}40Hz\;to\;1{\times}10^8Hz$. We obtained complex electrical conductivity, dielectric constant, and loss tangent(tan${\delta}$) of the device at room temperature. And, we obtained the equivalent circuit of $ITO/Alq_3/Al$ through analyzing dielectric constant and dielectric loss tangent. From these analyses, we could interpret a conduction mechanism and dielectric polarization.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.8
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• pp.323-330
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• 1985

Dielectric loss tangent and ac dielectric strength of GFRP (Glass Fiber Reinforced Plastics, G-10)was investigated as parameters of mechanical and thermal stresses, in order to study the basic dielectrical characteristics of composite insulating materials. The dielectric loss tangent was increased and the ac dielectric strength was decreased with increase in the mechanical stresses beyond the mechanical yield point on account of fiber-matrix debonding, but the dielectric constant was not varied sigificantly. the dielectric strength of G-10 was about 2 MV/cm and the dielectric constant was about 4.8.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.1
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• pp.43-47
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• 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 Korea Institute of Military Science and Technology
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• v.10 no.3
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• pp.114-119
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• 2007

Dielectric properties of quartz glass and $Si_3N_4$ are investigated using the waveguide method from room temperature to $800^{\circ}C$. For the case of dielectric constant, $Si_3N_4$ showed similar increase with quartz glass up to $300^{\circ}C$, but less increase from $300^{\circ}C$ to $800^{\circ}C$. For the case of loss tangent, those showed gradual increase with temperature except of some temperature points. The loss tangent of $Si_3N_4$ and quartz glass increased up to 18.2% and 12.5% respectively. Through these researches, high temperature dielectric properties of silicon nitride materials are characterized.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.187-190
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• 1998

In this paper a probe for the' measurement of dielectric properties of dielectric sheet materials is designed and implemented as a coaxial air line type. Using the broadband impedance method with this measurement probe the dielectric constant and loss tangent of the glass-epoxy and teflon are determined in the frequency range of 0.1 - l.O[GHz] with the temperature variation from $25[^{\circ}C]$ up to $65[^{\circ}C]$. A measured relative dielectric constant of the glass-epoxy is 4.42 and a loss tangents is 0.019 relatively, and the relative dielectric constants of teflon is 2.17 and a loss tangents is 0.002 relatively

• Investigative Magnetic Resonance Imaging
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• v.20 no.1
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• pp.36-43
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• 2016

Visualization of the tissue loss tangent property can provide distinct contrast and offer new information related to tissue electrical properties. A method for non-invasive imaging of the electrical loss tangent of tissue using magnetic resonance imaging (MRI) was demonstrated, and the effect of loss tangent was observed through simulations assuming a hyperthermia procedure. For measurement of tissue loss tangent, radiofrequency field maps ($B_1{^+}$ complex map) were acquired using a double-angle actual flip angle imaging MRI sequence. The conductivity and permittivity were estimated from the complex valued $B_1{^+}$ map using Helmholtz equations. Phantom and ex-vivo experiments were then performed. Electromagnetic simulations of hyperthermia were carried out for observation of temperature elevation with respect to loss tangent. Non-invasive imaging of tissue loss tangent via complex valued $B_1{^+}$ mapping using MRI was successfully conducted. Simulation results indicated that loss tangent is a dominant factor in temperature elevation in the high frequency range during hyperthermia. Knowledge of the tissue loss tangent value can be a useful marker for thermotherapy applications.

• Journal of electromagnetic engineering and science
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• v.14 no.4
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• pp.382-386
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• 2014

The knowledge of substrate material properties is important in antenna design. We present a technique to accurately characterize the dielectric constant and loss tangent of an antenna substrate based on the measurements of antenna's reflection coefficient and bandwidth. In this technique, an error function is formulated by combinations of the reflection coefficient and bandwidth of measured and simulated data, and then an optimization technique is used to efficiently search for the substrate properties that minimize the error function. The results show that the method is effective in retrieving the dielectric constant and loss tangent of the antenna substrate without the need of additional test fixtures as in conventional substrate characterization methods.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.309-310
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• 2005

Generally, the dielectric constant and loss tangent are gotten by resonators. This paper presents analysis of the comparing the dielectric constant and loss tangent from the Ring, T and series gap structures. The T structure can be analyzed easily at wideband characteristic with simple design. the Ring can ignore the radiation loss from the open-ended effect. the Series gap can get more accurate permittivity than a Ring structure. The Used materials were dupont9599 LTCC ceramic and daeju0086 Ag.