• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.72-74
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• 2014

Multilayer ceramic capacitor (MLCC) makes acoustic noise of electronic devices. Conversed piezoelectric effect of dielectric substance consists of $BaTiO_3$ causes vibration of MLCC so it must be analyzed to reduce the noise. Thus, finite element model for piezoelectric analysis of MLCC was constructed in this paper. Piezoelectric characteristics of MLCC was considered for the accurate simulation result. Displacement response for sinusoidal voltage signal was measured and simulation result was verified with test result.

• Journal of the Korean Ceramic Society
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• v.46 no.2
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• pp.155-160
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• 2009

The reliability could be one of the essential properties for multilayer ceramic capacitor (MLCC) using in various electronic devices and the concentration and mobility of oxygen vacancy would play important role in the reliability. To investigate the migration behavior of oxygen vacancies, thermally stimulated depolarization current (TSDC) is adopted. In dielectric material of X5R MLCC, the TSD-Current peak observed around 150$^{\circ}C$ and 200$^{\circ}C$ which represented the migration of oxygen vacancy. Substituting Yttrium for Dysprosium in X5R MLCC showed higher migration activation energy and lower TSD current density.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.114-117
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• 2001

$(Ba_{0.6-x}Sr_{0.4}Ca_x)TiO_3$(x=0.10, 0.15, 0.20) ceramics were fabricated by the mixed-oxide method and their structural and dielectric properties were investigated with variation of composition ratio and sintering temperature. As a result of the differential thermal analysis(DTA), exothermic peak was observed at around $1020^{\circ}C$ due to the formation of the polycrystalline perovskite phase. BSCT(50/40/10) specimen sintered at $1500^{\circ}C$ showed the highest average grain size(18.25$[{\mu}m]$). Curie temperature and dielectric constant at room temperature decreased with increasing amount of Ca. BSCT(50/40/10) specimen sintered at $1450^{\circ}C$ showed a good dielectric constant, K, (=4324) and dielectric loss, $tan{\delta}$, (=0.972%) properties at 1[KHz].

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.12
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• pp.843-846
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• 2015

In this paper, the failure mechanism of PTC heater were examined closely by failure analysis and based on it, accelerated life test were conducted. Finally, life distribution and acceleration model were established. The failure mechanism of PTC heater such as crack, increase of resistance due to heating were identified. Two acceleration factors such as temperature, humidity were chosen with two levels each and accelerated life test were done. Life distribution were identified as Weibull distribution with shape parameter 5.4 and Temperature-Humidity model was fitted as an acceleration model.

• Journal of the Korean Ceramic Society
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• v.30 no.12
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• pp.1066-1070
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• 1993

When looked upon as a polycrystalline, ceramics have two basic differences from a single crystal. One is that there exist grain boundaries, the other is that the crystal axes of each small crystal are arranged in random directions. But the crystal axes fo small crystals which compose ceramics may be made to have the tendency of being arranged in a specific direction. This is called that the crystal axes are oriented. The degree of the direction arrangement of the crystal axes is called orientation. In order to orient the crystal axes effectively, the fiberous barium titanates were made through KDC method and the ion exchange method. And then they were arranged through pressing, doctor blade, and syringe. As the result of Lotgering evaluation, the sample oriented through syringe showed the highest orientation. After sintering, though the most particles that had been fiberous shaped became global shape viewed through SEM, the orientation of the crystals was reinforced by means of sintering.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.5
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• pp.396-401
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• 2000

In order to accurately measure the high voltage of 22.9[kV] power distribution lines we investigated the temperature dependence of measuring voltage on the number of stack layers in the voltage measurement system made from single and stack voltage divider capacitors (22, 44, 66 layers, respectively). Temperature coefficient of dielectric constant(TC$\varepsilon_{{\gamma}}$/)of voltage divider capacitors which were fabricated by BaTi $O_3$system ceramics showed the variations from -2.28% to +1.69% in the range of -25[$^{\circ}C$] ~50[$^{\circ}C$]) was decreased with increasing of stack number and the stack element of 66 layers showed the least error of $\pm$0.87%or of $\pm$0.87%.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.5
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• pp.207-210
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• 2001

In this paper, the Flexible information display was implemented uing AC powder electroluminescent device. ZnS:Cu and $BaTiO_3$ were used as a phosphor and dielectric respectively. The growth of phosphor and dielectric layer was performed with screen printing. The flexible information display in this paper was categorized as following; EL display, driving circuit, software for driving. EL spectrum and brightness was measured as the device properties.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.5
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• pp.349-353
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• 1999

In this paper, to fabricate the AC power electroluminescent device (PELD) with high brightness, new structure that constructed single emissive layer between electrodes was proposed. Dielectric and phosphor material structure that constructed single emissive layer between electrodes was proposed. Dielectric and phosphor material were BaTiO3 and ZnS:Cu respectively. Fabricated AC power EL devices were estimated by optical and electrical properties of EL spectrum, brightness, CIE coordinate system, transferred charge density and EL emission wave in time domain. With above results, we found that brightness of newly proposed AC powder EL power EL device was 2754 cd/m2 at 100V, 400 Hz and compared with conventional device structure.

• Transactions of the Society of Information Storage Systems
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• v.10 no.2
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• pp.61-64
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• 2014

Vibration and acoustic noise arise from the Multilayer Ceramic Capacitor (MLCC) because of the piezoelectric effect of dielectric substance which consists of $BaTiO_3$. However, the phenomenon is not analyzed clearly because the MLCC shows different behavior compare with ordinary piezoelectric substance like PZT. Thus, MLCC was tested under the several DC bias conditions and heat treatment effect was also tested and analyzed in this paper. From the test, MLCC shows not only piezoelectric effect but also another physical phenomenon like electrostriction. Also, it was verified that DC bias affect to the piezoelectric constant of MLCC.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1529-1531
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• 2003

Thick film mechanical sensors can be categorized into four main areas piezoresistive, piezoelectric, piezocapastive and mechanic tube. In this areas, the thick film strain gage is the earliest example of a primary sensing element based on the substrates. The latest thick film sensor is used various pastes that have been specifically developed for pressure sensor application. The screen printing technique has been used to fabricate the pressure sensors on alumina substrate($Al_2O_3$). Thick film capacitive of strain sensing characteristics are reported and dielectric paste based on (Ti+Ba) materials. The electric property of dielectric paste has been studied and exhibit good properly with good gage factor comparable to piezoresistive strain gage. New piezocapacitive strain sensor was designed and tested. The output of capacitive value was good characteristics.