• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.385.2-385
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• 2002

Hermetic rotary compressor is one of the most important components for air conditioning system since it has a great effect on both the performance and the noise and vibration of the system. Noise and vibration of rotary compressor is occurred due to gas pulsation during compression process and unbalanced dynamic force. In order to reduce noise and vibration, it is necessary to identify sources of noise and vibration and effectively control them. (omitted)

• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.157-159
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• 2005

In this study, in order to develop Pb-free piezoelectric ceramics, $[Li_{0.04}(Na_{0.44}K_{0.52)-(Nb_{0.86}Ta_{0.10}Sb_{0.04})]O_3$ ceramics were fabricated by conventional mixed oxide method and their piezoelectric characteristics were investigated according to the poling condition. The transition temperature from orthorhombic phase to tetragonal phase observed at $93[^{\circ}C]$ and Curie temperature was $346[^{\circ}C]$. At $50[^{\circ}C]$ poling temperature, dielectric constant, electromecha nical coupling factor kp, piezoelectric $d_{33}$ const ant, coercive field Ec, remanant polarization Pr and mechanical quality factor Qm showed the optimum value of 737, 0.45, 209[pC/N], 1l.34[kV/cm], $7.14[{\mu}C/cm^2]$ and 205, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.61-65
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• 2008

In this paper, we studied a ZnO-based film bulk acoustic resonator (FBAR) device fabricated on a specially designed multi-layerd Bragg reflector part. Very thin chromium adhesion layers (0,03um thick) were additionally deposited to improve the quality of the Bragg reflector and some thermal treatments were performed to improve the resonant characteristics of the device. At the operating frequency of ${\sim}2.7GHz$, excellent resonant characteristics were observed in terms of return loss and quality factor, and effective electromechanical coupling coefficient. These findings are expected to be highly promising and effective for improving the performance of the FBAR devices at high frequency.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.434-437
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• 2001

In this study piezoelectric and dielectric properties of $Pb(Mn_{1/3}Nb_{2/3})O_{3}-Pb(Zr,Ti)O_{3}$ ceramics were investigated with $Pb(Ni_{1/3}Nb_{2/3})O_{3}$ substitution. As the $Pb(Ni_{1/3}Nb_{2/3})O_{3}$ substitution was increased, dielectric constant and electromechanical coupling factor (kp) were increased while mechanical quality factor decreased.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.33 no.9
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• pp.355-363
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• 1984

An ideal and an approximate eauivalent circuits of a face-mounted PZT piezoelectric transformer were introduced from the equivalent circuit taking into account the mechanical loss of a PZT piezoelectric disk vibrator. And several expressions for the resonant frequencies and for the voltage ratios were derived from the approximate circuit of the transformer. From the experiments on the vltage ratios regarding the frequency variation without load and on the load variation at resonant frequency, it was found that the voltage ratio increased with the increase of load resistance and decreased sharply with the slight deviation from the resonant frequency, and that no-load voltage ratio at the resonant frequency was proportional to the product of the mechanical quality factor and the square of the electromechanical coupling factor of the vibrator.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.204-205
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• 2005

[ $(Na_{0.5},\;K_{0.5})NbO_3$ ] ceramics were studied as lead free Piezoelectric materials. The addition of CdO were enhanced the sinterability of the NKN ceramics. The $(Na_{0.5},\;K_{0.47}Cd_{0.02})NbO_3$ ceramics show that electromachanical coupling factor($k_p$) is 0.34and mechanical quality factor($O_m$) is 120.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.1
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• pp.33-39
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• 2003

Interior parts of a vehicle are getting important to reduce interior noise. Therefore, prior analysis of cabin noise related with interior parts are necessary at first design stage. Recently, Statistical Energy Analysis(SEA) has been suggested as a possible way for high frequency range noise analysis of interior parts. The validity of noise analysis with SEA to interior parts has been preyed by comparing with experimental result, and the developed method with SEA has been applied in finding optimized interior parts package.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.322-325
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• 2002

In this study, dielectric and piezoelectric properties of PSN-PZT Ceramic were investigated as a function of PNW substitution. With the increase of PNW substitution, teragonality, Curie temperature and mechanical quality factor were decreased but grain size and electromechanical coupling factor(kp) was gradully increased. At 4 mol [%] PNW substitution. maximum kp of 0.567 was shown.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1510-1512
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• 1997

Piezoelectric characteristics of lead zirconate(PZ)-lead titanate(PT)-lead manganese antimony(PMS) ceramics with the various changes of calcination temperature in PMS were prepared. The range of their sintering temperature was from $1100^{\circ}C$ to $1250^{\circ}C$. The electro-mechanical properties of PZ-PT-PMS ceramics such as piezoelectric constant, electro-mechanical coupling coefficient, and mechanical quality factor are measured as a function of the calcination temperature of PMS. As increasing the calcination temperature of PMS mechanical quality factor is increased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03a
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• pp.1-1
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• 2010

In this study, electrical properties of multilayer piezoelectric transformer sintered at $900^{\circ}C$ using pure Ag internel electrode was investigated. This multilayer piezoelectric transformer was fabricated as a ring-dot type. The multilayer piezoelectric transformer should have hight electromechanical coupling factor ($k_p$) and electromechanical qualiy factor ($Q_m$) in order to increase the efficiency of energy conversion between electrical and mechanical energy. The maximum values of $k_p$ and $Q_m$ showed 0.552 and 1320, respectively.