• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.1
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• pp.31-38
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• 2004

PMN-PT, a piezoelectric single crystal, has many useful applications such as sensors and actuators. In this paper, all the elastic, piezoelectric, and dielectric constants of the PMN-32％PT single crystals were measured by the resonance method. For the rhombohedral symmetry, a total of twelve independent material constants were measured such as six elastic compliance constants at constant electric field, two dielectric constants at constant stress, and four piezoelectric constants d. Seven sets of crystal samples of each different geometry were prepared for the measurement of length-thickness extensional, thickness extensional, radial, length extensional and thickness shear modes of vibration, respectively. In order to check the validity of the measurement, experimental impedance spectrum of the PMN-PT crystal was compared with numerical data spectrum calculated with the measured material constants. The good agreement between the two spectra confirmed validity of the results in this paper.

• Smart Structures and Systems
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• v.15 no.6
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• pp.1411-1437
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• 2015

The electro-magneto- thermo-elastic behavior of a rotating functionally graded long hollow cylinder with functionally graded piezoelectric (FGPM) layers is analytically analyzed. The layers are imperfectly bonded to its inner and outer surfaces. The hybrid cylinder is placed in a constant magnetic field subjected to a thermo-electro-mechanical loading and could be rested on a Winkler-type elastic foundation. The material properties of the FGM cylinder and radially polarized FGPM layers are assumed to be graded in the radial direction according to the power law. The hybrid cylinder is rotating about its axis at a constant angular velocity. The governing equations are solved analytically and then stresses, displacement and electric potential distribution are calculated. Numerical examples are given to illustrate the effects of material in-homogeneity, magnetic field, elastic foundation, applied voltage, imperfect interface and thermo-mechanical boundary condition on the static behavior of a FG smart cylinder.

• The Korean Journal of Ceramics
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• v.5 no.3
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• pp.245-249
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• 1999

A new type of nonthermal plasma reactor utilizing ferroelectric pellets is proposed to generate nonthermal plasma efficiently, which is used for simultaneous control of various pollutant gases. Electric charges stored on ferroelctric pellets by corona discharge between a corona tip and a mesh electrode provide partial electrical discharges among ferroelectric pellets. These partial electrical discharges can enhance partial discharges around the surface of ferroelectric pellets. This method utilizes wide reacting area of ferroelectric pellets and partial discharge. Positive and negative dc voltage are applied to the corona tip to generate partial discharges, and corona currents are estimated to investigate charge storage on ferroelectric pellets as function of time and charge relaxation time constants of ferroelectric pellects. As a result, charge relaxationtime, dielectric constants of ferroelectric pellets, polarity of applied voltage and applied time influence partial discharges among ferroelectric pellect.

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.29-32
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• 2000

Meta1-ferroelectric-insulator-semiconductor(MFIS) devices using Pt/LiNbO$_{3}$/AIN/Si structure were successfully fabricated. AIN thin films were made into metal-insulator-semiconductor(MIS) devices by evaporating aluminum in a dot array on the film surface. The dielectric constant of the AIN film calculated from the capacitance in the accumulation region in the capacitance-voltage(C-V ) characteristic is 8. The gate leakage current density of MIS devices using a aluminum electrode showed the least value of 1$\times$10$^{-8A}$ $\textrm{cm}^2$ order at the electric field of 500㎸/cm. A typica] value of the dielectric constant of MFIS device was about 23 derived from 1MHz capacitance-voltage (C-V) measurement and the resistivity of the film at the field of 500㎸/cm was about 5.6$\times$ 10$^{13}$ $\Omega$.cmcm

• Journal of Sensor Science and Technology
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• v.23 no.1
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• pp.1-6
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• 2014

In many medical image devices, dc noise often prevents normal diagnosis. In wireless capsule endoscopy systems, multipath fading through indoor wireless links induces inter-symbol interference (ISI) and indoor electric devices generate impulsive noise in the received signal. Moreover, dc noise, ISI, and impulsive noise are also found in optical fiber communication that can be used in remote medical diagnosis. In this paper, a blind signal processing method based on the biased probability density functions of constant modulus error that is robust to those problems that can cause error propagation in decision feedback (DF) methods is presented. Based on this property of robustness to error propagation, a DF version of the method is proposed. In the simulation for the impulse response of optical fiber channels having slowly varying dc noise and impulsive noise, the proposed DF method yields a performance enhancement of approximately 10 dB in mean squared error over its linear counterpart.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.11 s.176
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• pp.104-110
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• 2005

GIS(Gas Insulated Switchgear) is used in electric power system, to insure non conductivity, breaking capacity and operating reliability. The commercial dynamic analysis code COSMOS MOTION and 3-D modeling program SOLID WORKS were used to simulate dynamic analysis of the closing resistors of the GIS in this paper. To reduce chatter vibration of closing resistors, the motion of moving and fixed parts of closing resistors were simulated by varying the spring constant, the damping coefficient and the mass of moving and fixed parts. The simulated results were compared with experimental results. As a result, chatter vibration of closing resistors of the GIS could be reduced by using the results. These data can be used to determine the spring constant, the damping coefficient and mass of a moving part to reduce chatter vibration when the next model is developed.

• 전기의세계
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• v.30 no.10
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• pp.639-644
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• 1981

PVC is a kind of electric insulation polymer. But we get some deteriorations in electrical characteristics of the PVC, when it is used on the radioactive field. In order to find out the cause of the deterioration, we investigate the surface-resistance, volume-resistance, dielectric constant and dielectric loss angle of the soft and hard PVC which is irradiated by the Co$^{60}$ .gamma. radioactivity. From the experiment, we can conclude the followings 1. Radio-activity proof characteristic in the soft PVC is stronger than in the hard PVC. 2. The resistance of PVC which is irradiated by the radio-activity decrease exponentially. 3. The dielectric constant and the dielectric loss angle of PVC irradiated by Co$^{60}$ .gamma.ray reach maximum value in first few time.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.2
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• pp.130-135
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• 2005

In this papers, we made study for plastic chip antenna, the plastic is Foamex with the circle of PVC and its electric characteristics are dielectric constant 1.9, insulation intensity 112 KV/cm. The proposed antenna is same as the conventional antennas are usually constructed with ceramic chip, which are not fragile in nature and don't tend to break easily. Therefore the proposed antenna with its advantage is attractive for application in mobile antenna. In order to valid the proposed papers, it is implemented the antennas of four types and experimented. From the results, we conformed that the antennas are operated at the dual band which is cellular band and Korea-PCS band. And the gain of the antennas has about above -2 dB and the pattern is same as conventional antennas. From this papers, the realized antennas using Foamex material will be application for mobile phone antenna.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.283-285
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• 1987

Transient conduction current (I - t characteristics) were measured in thin PPMMA (plasma-polymerized methyl methacrylate) films over the temperature range $60^{\circ}C-140^{\circ}C$ and the applied voltage range 3V - 30V. The current, which increased with temperature rise at constant applied voltage, showed less absorption current (current decay with time) at higher temperature region compared with those at lower temperature region. And the current, which increased with applied voltage rise at the constant temperature, showed less absorption current at higher voltage compared with those at lower voltage. The electric field current density characteristic curves were abtained from the conduction current values were after applying voltage for 30 minutes. And transient conduction currents were analyzed with high field conduction theories.

• Journal of Electrical Engineering and information Science
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• v.2 no.3
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• pp.132-138
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• 1997

Electrical characteristics of split-gate flash EEPROM with triple polysilicon is investigated in terms of effects of floating gate and offset gate. In order to search for t the effects of offset gate on programming characteristics, threshold voltage and drain current are studied with variation of control gate voltage. The programming process is believed to depend on vertical and horizontal electric field as well as offset gate length. The erase and program threshold voltage are found to be almost constant with variation of control gate voltage above 12V, while endurance test indicates degradation of program threshold voltage. With increase of offset gate length, program threshold voltage becomes smaller and the drain source voltage just after program under constant control gate voltage becomes higher.