• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.6
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• pp.460-465
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• 2001

(Ba$_{0.6-x}$Sr$_{0.4}$Ca$_{x}$)TiO$_3$(x=1.10,0.15,0.20) specimens were fabricated by the solid state reaction method and then the structural and dielectric properties as a function of he composition ratio and sintering temperature were studied. As a result of the differential thermal analysis(DTA), exothermic peak was observed at around 102$0^{\circ}C$ due to the formation of the polycrystalline perovskite phase. The BSCT(50/40/10) specimen sintered at 150$0^{\circ}C$ showed the highest average grain size(18.25${\mu}{\textrm}{m}$). The Curie temperature and dielectric constant at room temperature decreased with increasing Ca content. The dielectric constant and dielectric loss of the BSCT(50/40/10) specimen, sintered at 145$0^{\circ}C$, were about 4324 and 0.972% at 1KHz, respectively.ively.

• Journal of the Korean Ceramic Society
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• v.32 no.8
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• pp.938-944
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• 1995

Dielectric properties and the stabilization of perovskite phase for the (1-y)Pb(Mg(1-x)/3Znx/3Znx/3Nb2/3)O3-yBaTiO3 ((1-y)PM1-xZxN-yBT) ceramics have been investigated as a function of amount of x and y. In the (1-y)PM0.6Z0.4N-yBT ceramics, the amount of pyrochlore phae was decreased by the addition of 2 mol% BT and the dielectric constant was increased. However, the dielectric constant decreased with further addition of BT even though pyrochlore phase was decreased. Dielectric prooperties in (1-y)PM0.6Z0.4N-yBT ceracmis were affected by the character of the BT rather than the amount of pyrochlore phase. The phase transitions were broadened and phase transition temperatures were lowered by the increase of BT contents.

• Journal of the Korea Convergence Society
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• v.6 no.5
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• pp.9-14
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• 2015

In this paper, we analysis the electromagnetic scattering of an arbitrary shape dielectric cube subjected to plane wave incidence in three dimensions. MoM(Method of Moments)in which a surface of a body is divided with small triangular patches and equivalence principle are used to fuse the PMCHW(Poggio, Miller, Chang, Harrington, and Wu) Integral Equations with respect to equivalent currents on a dielectric body. Triangular patch and loop-patch basis functions that is robust in wide frequency ranges are used for MoM formulations. Proposed method is very useful to analysis the induced current of arbitrary dielectric bodies and numerical results for a dielectric cube are presented.

• Journal of the Korean Ceramic Society
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• v.48 no.3
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• pp.257-262
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• 2011

Dependencies of dielectric properties on $MgTa_2O_6$, $MgNb_2O_6$, and $MgWO_4$ (Mg-based ceramics) fillers of the polystyrene (PS) matrix composites were investigated as a function of frequency. With increasing frequency from 1 GHz to 7.3 GHz, the dielectric constant (K) of the composites was not changed significantly, while the dielectric loss (tan${\delta}$) of the composites was slightly decreased. The K, tan${\delta}$, and temperature coefficient of resonant frequency (TCF) of the composites were dependent on the type and amount of ceramics at 11 GHz. Also, several theoretical models have been employed to predict the effective dielectric constant of the composites and the results were compared with experimental data. Typically, a K value of 6.67, tan${\delta}$ of $0.56{\times}10^{-3}$, and TCF of -4.99 $ppm/^{\circ}C$ were obtained for the PS composites with 0.4 volume fraction of $MgNb_2O_6$ at 11 GHz.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.10a
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• pp.105-107
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• 1988

The dielectric properties of complex perovskite compound Sr$(Mg_{1/3}Mb_{2/3})$$O_3$-Ba$(Mg_{{1/3}Nb_{2/3})$$O_3$(BMN) system were investigated as a function of composition and sintering time. In the case of the specimens sintered at $1650^{\circ}C$ for same time, dielectric constant and dielectric loss were increased with increasing the mole ratio of BMN. The maximum temperature coefficient of resonant frequency was found in composition Ba$(Mg_{{1/3}Nb_{2/3})$$O_3$. In the case of the specimens with same composition, dielectric constant and dielectric loss were slightly increased with increasing the sintering time. As the sintering time was increased, the temperature coefficient of resonant frequency for SMN was slightly increased, however, that of BMN and ($Sr_{1/2}Ba_{1/2}$) ($Mg_{1/3}Ta_{2/3}$)$O_3$ was largely depended on sintering time.

• Journal of the Korean Society of Safety
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• v.20 no.4 s.72
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• pp.29-33
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• 2005

In this paper, reflectance and the dielectric characteristics for $P_2O_5-ZnO-BaO$ system and $SiO_2-ZnO-B_2O_3$ system have been investigated as a function of contents of $TiO_2$. The reflectance was decreased with increasing the contents of $TiO_2$ and the reflectance of $P_2O_5-ZnO-BaO$ system was lowered than that of $SiO_2-ZnO-B_2O_3$ system. The dielectric constant of $P_2O_5-ZnO-BaO$ system was higher than $SiO_2-ZnO-B_2O_3$ system, and the dielectric constant in the both system was increased with increasing of $TiO_2$ contents. This can be explained as the space charge effects. These results are could be applied to the under plate dielectrics of PDP required high reflective ratio and breakdown strength.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.320-324
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• 2015

Mutual coupling between antenna elements of a linear microstrip patch antenna array positioned along the H-plane including the effect of edge reflections is investigated. Simple formulas are presented for the estimation of the grounded dielectric substrate size with minimum mutual coupling. The substrate sizes calculated by these formulas are in good agreement with those obtained by the full-wave simulation and experimental measurement. The substrate size with minimum mutual coupling is a function of the effective dielectric constant for surface waves and the distance between the antenna centers. The substrate size with minimum mutual coupling decreases as the effective dielectric constant for surface waves on a finite grounded dielectric substrate increases.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.7
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• pp.26-31
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• 1993

We have analyzed shielding characteristics of the spherical multilayered dielectric, with the assumption that the inner part of the model is filled with the perfect conductor whose radius is varied from 0.2.lambda. to 1.0.lambda. and the outer part of the conducting sphere is covered by a lossy multilayered dielectric. Variation of shielding effects have been examined as the function of parameter of the dielectric layer and the radius of the conducting sphere.

• Proceedings of the Optical Society of Korea Conference
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• 1990.02a
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• pp.64-68
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• 1990

Boundary element method using linear basis function is applied to obtain fields scattered from a 3-D dielectric sphere. Electric field integral equation is used on the surfaces of the dielectric material where its surface is discretized into trilateral cells. For plane wave incidence, scattered fields by a dielectric sphere is calculated and compared with its analytic solution. The total electric fields are calculated on the great circle of the sphere boundary as well as the outside of the sphere in the plane of the wave vector and the polarization vector of the incident electric field.

• Journal of the Korean Ceramic Society
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• v.22 no.2
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• pp.63-67
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• 1985

$BaTiO_3$ and $SrTiO_2$ were mixed with the mole ratio of 36:65:50, 50: 50 and 65:35 and then heated at 110$0^{\circ}C$~130$0^{\circ}C$ for 1~64 hrs. The solid state reactions and dielectric properties were investigated as a function of amount of solid solution. Activation energy of solid solution decreased with increasing amount of $BaTiO_3$ due to fast diffusion of $Ba^{2+}$ ions. Dielectric constants increased with increasing the soaking time at 125$0^{\circ}C$and 130$0^{\circ}C$ and Curie Temperature shifted to higher temperature with increasing the soaking time at 125$0^{\circ}C$ and 130$0^{\circ}C$. It attributes to the am-ount of solid solution and grain growth, Dielectric constants decreased and Curie Temperature shifted to lower temperature due to decreasing polari-zability.