• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.41-44
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• 1998

(1-X)LTC-XHTC composites were manufactured with the variation of X in the range of 0.3 $\leq$X $\leq$0.6 and its dielectric properties were investigated. Here, LTC and HTC are PZN-BT-PT -based ceramics with quire temperature(Tc) of 100。 C-3$0^{\circ}C$, respectively. 0.6HTC-0.4LTC composite ceramics show excellent values of $\Delta$$\varepsilon$$_{r}$/$\varepsilon$[%] which were -7.1% at -2$0^{\circ}C$ and -12% at 5$0^{\circ}C$, respectively. It is thought that composite ceramics with above results can be applied to electrostrictive actuator, high voltage ceramic capacitor etc.mic capacitor etc.r etc.c.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.674-677
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• 2002

In this paper, two kinds of windmill type motors which have a disk shape and a ring shape piezoelectric ceramics were studied. And characteristics of two models were compared with each others. A windmill type ultrasonic motor is composed of a stator, a rotor, and a ball bearing. The stator is made of a piezoelectric ceramics and two metals endcaps. When the piezoelectric ceramics vibrate, displacement of torsonal vibration appear at metal endcaps. The motor with 11.0[mm] diameter was studied by finite element analysis. The voltage of 100[V] was supplied at each model. Resonance frequency of 206.875[KHz] was obtained at the disk type, but ring type was 137.562[KHz]. The maximum torsonal displacement of $1.112[{\mu}m]$ was obtained at the disk type, but ring type was $1.698[{\mu}m]$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.3
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• pp.208-213
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• 1998

Microwave dielectric properties of $BiNbO_4$ containing CuO and $V_2O_5$(BN ceramics). BN ceramic with 0.07wt% $V_2O_5$ and 0.03wt% CuO (BNC3V7) was sintered at $900^{\circ}C$ where it is possible for these to be co-fired with Ag electrode. The dielectric constant of 44.3, TCF (Temperature Coefficient of resonance Frequency) of 2 ppm/$^{\circ}$ and Q${\times}f_o$ value (product of Quality value and resonance Frequency) of 22,000GHz could be obtained from those ceramics. It is observed that orthorhombic structure was stable $1000^{\circ}C$. As sintering temperature increases, the dielectric properties decreased. The main reasons were abnormal grain growth and the main peak of triclinic moved from the main peak of orthorhombic.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.109-114
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• 2002

Aging stabilities of the operating frequency of piezoelectric devices such as filter, oscillator and discriminator are very important. In this study it was studied aging stabilities of the length-extensional vibration mode of Pb(Zr$\_$y/Ti$\_$1-y/)O$_3$+x[wt%]Cr$_2$O$_3$ ceramics. PZT ceramics in Morphotropic phase boundary have higher aging rates of k$\_$31/ and resonant frequency than those in tetragonal phase or rhombohedral phase. Thermal aging moves the composition with maximum aging rate to Zr-rich side in Cr not added PZT system. Aging rate of resonant frequency of the ceramics with x=0.1, y=0.53 and x=0.3, y=0.53 increased by thermal aging.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.656-659
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• 2003

In this study, in order to develop the low temperature sintering ceramics for multilayer piezoelectric transformer, dielectric and piezoelectric properties of PSN-PZT ceramics were investigated according to Zr/Ti ratio. As Zr/Ti ratio is increased, coupling factor(kp) and dielectric constant were increased and then decreased after the ratio of Zr/Ti=50/50. And also, mechanical quality factor were decreased and then increased after the ratio of Zr/Ti=50/50.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.05a
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• pp.11-14
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• 1993

$BaO-TiO_2$ ceramics ($BaO:TiO_2$=18.2:81.8[mol.%]) were fabricated by mixed-oxide method. Microwave dielectric properties were investigated with sintering temperature and annealing time. Increasing the sintering temperature, the sintered density was decreased. At the sintering temperature of 1400$[^{\circ}C]$, dielectric constant, quality factor and temperature coefficient of resonant frequency had a good values of 35.03, 5690, -4.433$[ppm/^{\circ}C]$, respectively. Increasing the annealing time, dielectric constant and quality factor were increased and temperature coefficient of resonant frequency was decreased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.305-305
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• 2010

In this study, in order to develop excellent lead free piezoelectric ceramics for piezoelectric transformer application (Na,K)(Nb,Sb)$O_3$ ceramics were fabricated using conventional oxides mixed method and their piezoelectric and dielectric characteristics were investigated according to the amount of $Bi_2O_3$ addition.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.6
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• pp.36-43
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• 2003

In machining of ceramic materials, they are very difficult-to cut materials because of there high strength and hardness. Machining of ceramics are characterized by cracking and brittle fracture. Generally, ceramics are machined using conventional method such as finding and polishing. However these processes are generally costly and have low MRR(material removal rate). This paper focuses on determining the optimal levels of process parameters for products with CNC machining center. For this purpose, the optimization of cutting parameters is performed based on experimental design method. A design and analysis of experiments is conducted to study the effects of these parameters on the surface roughness by using the S/N ratio, analysis of ANOVA and F-test. Cutting parameters, namely, cutting speed, feed and depth of cut are optimized with consideration of the surface roughness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.317-320
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• 1999

In this study, the piezoelectric ceramics PZT powder was synthesized by Wet-Dry combination method. And the flexible 1-3-0 type composites were fabricated with piezoceramic PZT and Eccogel polymer matrix embedded 3rd phase. Dielectric constant of 1-3-0 type composites was lower than that of single phase PZT ceramics. Thickness mode coupling factor k/sub t/ which was comparable with single phase PZT ceramics and mechanical quality factor Qm were about 0.65 and 6, respectively. These composites are considered as a good candidates for broad-band type transducer applications. The acoustic impedance of 1-3-0 type composites was lower than that of single phase PZT ceramics. Therefore, these composites would be better used for hydrophone applications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.304-307
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• 1999

The Mg($_{1-x}$ )S $r_{x}$Ti $O_3$(x=0.1,0.2,0.3) ceramics were prepared by the conventional mixed oxide method. The structural properties were investigated with calcining temperature and composition ratio by XRD and DT-TGA. Increasing the calcining temperature from 80$0^{\circ}C$ to 100$0^{\circ}C$, second phase was decreased and average particle size was increased. The SrTi $O_3$ ceramics of calcined at 100$0^{\circ}C$ had a structure of polycrystalline perovskite without the secondary phases. The average particle size of the $Mg_{0.9}$S $r_{0.1}$Ti $O_3$ ceramics calcined at 100$0^{\circ}C$ were 0.67${\mu}{\textrm}{m}$..>......