• Proceedings of the KIEE Conference
• /
• 1997.07c
• /
• pp.883-885
• /
• 1997

High impedance fault(HIF) is random in its behavior even in a similar environment. The detection of Ire HIF has focused on the development of algorithms based on harmonic, parameters of the arc currents. However, a fact that proper selection of the harmonic parameters, rather than algorithm selection, is more important is shown in this paper by applying three different performance evaluation methods on two HIF detection algorithms using eight harmonic parameters.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.11a
• /
• pp.347-350
• /
• 2000

The purpose of this study is to research and develop solid polymer electrolyte(SPE) for Li polymer battery. The temperature dependence of conductivity, impedance spectroscopy and electrochemical properties of PMMA/PVDF electrolytes as a function of a mixed ratio were reported for PMMA/PVDF based polymer electrolyte films, which were prepared by thermal gellification method of preweighed PMMA/PVDF, plasticizer and Li salt. The ion conductivity of PMMA/PVDF electrolytes was 10$\^$-3/S/cm, which may be applicable to a constituent of lithium secondary battery. 5PMMA20PVDFLiC1O$_4$PC$\sub$8/EC$\sub$8/ electrolyte remains stable up to 5V vs. Li/Li$\^$+/. Steady state current method and AC impedance were used for the determination of transference numbers in PMMA/PVDF electrolyte film. The transference number of 5PMMA20PVDFLiC1O$_4$PC$\sub$8/EC$\sub$8/ electrolyte is 0.55.

• Smart Structures and Systems
• /
• v.4 no.1
• /
• pp.35-46
• /
• 2008

In this paper the authors address the problem of comparing two different smart damping techniques using the numerical modelling of the electro-mechanical impedance for plate structures partially treated with active constrained layer damping treatments. The paper summarizes the modelling procedures including a finite element formulation capable of accounting for the observed behaviour. The example used is a smart cantilever plate structure containing a viscoelastic material (VEM) layer sandwiched between a piezoelectric constrained layer and the host vibrating plate. Comparisons are made between active constrained layer and active damping only and based on the resonance frequency amplitudes of the electrical admittance numerically evaluated at the surface of the piezoelectric model of the vibrating structure.

• Journal of Magnetics
• /
• v.9 no.2
• /
• pp.47-51
• /
• 2004

Giant magneto-impedance (GMI) effect in zero-magnetostrictive Co-based amorphous ribbons samples in their as-quenched and stress-released states as well as with intentionally induced magnetic anisotropy were investigated. Magnetic and impedance properties of the samples exhibiting different anisotropy were compared and the optimum operation conditions for the studied samples from the view-point of their utilization as a sensor element have been determined. A design of a model of magnetic field sensor and characteristics of the constructed prototype are presented.

• Journal of the Korean Electrochemical Society
• /
• v.10 no.3
• /
• pp.179-183
• /
• 2007

The corrosion behavior of metal covered with mortar under a wet-dry cyclic condition were investigated to apply for the measurement of corrosion rates of reinforcing steel in concrete structure. The carbon steel in mortar having t=3 mm cover thickness was exposed to the alternate condition of 6 h immersion in chloride containing solution and 18 h drying at $25^{\circ}C$ and 50%RH. The electrochemical phenomena of a carbon steel and mortar interface was explained by an equivalent circuit consisting of a solution resistance, a charge transfer resistance and a CPE(Constant Phase Element). The corrosion rates were monitored continuously during exposure using an AC impedance technique. Simultaneously, the current distribution over the working electrode during impedance measurement was analyzed from the phase shift, $\theta$, in an intermediate frequency. The result showed that corrosion rate monitoring using an AC impedance method is suitable under the given exposure conditions even during the drying period when the metal is covered with the wetted mortar.

• Proceedings of the KIEE Conference
• /
• 2007.10a
• /
• pp.471-472
• /
• 2007

The scalp is skin tissue for skull-protection and roots for hair growth. Therefore continuous monitoring of scalp condition is essential for hair management. However, the equipments for existent are inconvenient to use because of focus tremor and external factors(Hair Gel, Wax, accessories and so on). Furthermore there is a problem to use an expensive optical devices like CCD (Charge Coupled Device) camera or lens of 200 - 1000 magnification. It causes a difficulty of using those equipment. We design the special electrode(length 5.65mm, diameter 0.8mm of needle shape) and the impedance system(1kHz, 78uA). Tn this paper, we can measure scalp impedance with our system. Moreover, we find the possibility of classifying scalp condition with measured impedance values. For the classification of scalp condition, we used ARAMO-TS as an imaging system. In conclusion, the problem of existent devices could be improved using these method. It also has a benefit of continuous monitoring of scalp condition.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.1 no.2
• /
• pp.57-61
• /
• 1987

The characteristis of all the instruments and materials used in atomic industry are changed due to irradiation damages by the effects of radiation activities. In this study when R-C series-parallel circuits are irradiated by $\gamma$-ray, variations in its electrical properties have been investigated. The following results are obtained. 1) In the R-C series circuit, the impedance variation ratio is increased as the irradiation quantity is increased up to $10^6[r]$, and above $10^6[r]$, the impedance variation ratio reached at the saturated condition. In the saturated condition, the increasing value was about 1.25 (%). 2) In the R-C series circuit, the power factor variation ratio is decreased as the irradiation quantity is in creased up to $10^6[r]$, and above $10^6[r]$, the power factor variation ratio reached at the saturated condition. In the saturated condition, the decreasing value was about 0.5(%). 3) In the R-C parallel circuit, the impedance variation ratio is increased as the irradiation quentity is increased up to $10^6[r]$, and above $10^6[r]$, the impedance variation reached at the saturated condition. In the saturated condition, the increasing value was about 0.5.(%). 4) In the R-C parallel circuit, the power factor variation ratio is decreased as the irradiation quantity is increased up to $10^6$[r], and above $10^6$[r], the power factor variation ratio reached at the saturated condition. In the saturated condition, the decreasing value was about 1.3(%).

• Transactions on Electrical and Electronic Materials
• /
• v.8 no.3
• /
• pp.131-134
• /
• 2007

An $ITO/Alq_3/Al$ structure was used to study complex impedance of $Alq_3$ based organic light-emitting diodes. Equivalent circuit was analyzed in a device structure of $ITO/Alq_3/Al$ with a thickness layer of $Alq_3$ of 100 nm. The obtained impedance was able to be fitted using equivalent circuit model of parallel combination of resistance $R_p$ and capacitance $C_p$ with a small series resistance of $R_s$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.2
• /
• pp.163-168
• /
• 2001

This dissertation describes the development of a sensor for measuring microscopic displacement where we use CoFeSiB amorphous alloy magnetic ribbon having near zero magnetostrictive properties. For the development of the sensor, we first fabricate amorphous alloy magnetic ribbon, and then investigate its physical and magnetic properties. Finally, its possibility of practical application as a displacement sensor is discussed. The experimental samples were made of near zero magnetostrictive (Co$\_$0.94/Fe$\_$0.06/)$\_$9/Si$_2$B$\_$19/ alloy which were fabricated by a rapid liquid quenching method. As a results, we got amorphous alloy magnetic ribbons of 12㎛ in thickness, 10 mm in length, and 2.5 m in width. It was found that the crystallization temperature and the Curie temperature are around 451$\^{C}$ and around 441$\^{C}$ respectively. We couldn't observe any noticeable change of the impedance frequency of 10MHz, but observed the impedance change of 3.76 %/Oe at 100 MHz. The inductance was nearly stable over the frequency range of 1∼10 MHz, In addition, it was observed that the variation of the inductance and the impedance were linear within the displacement ranges of 20∼60㎛. As the results of the experiments, it is suggested that the displacement sensor which is fabricated by using amorphous alloy magnetic ribbon of (Co$\_$0.04/Fe$\_$0.06/)$\_$79/Si$_2$B$\_$19/ compound, can be used as a sensor to detect microscopic displacement.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.11a
• /
• pp.320-321
• /
• 2006

In this work, impedance Spectroscopic analysis was applied to study the effect of plasma treatment on the surface of indium-tin oxide (ITO) anodes using $CF_4g$ as and to model the equivalent circuit for organic light emitting diodes (OLEDs) with the $CF_4$ plasma treatment of ITO surface at the anodes. This device with ITO/TPD/$Alq_3$/LiF/Al structure can be modeled as a simple combination of a resistor and a capacitor. The $CF_4$ plasma treatment on the surface of ITO shifts the vacuum level of the ITO as a result of which the barrier height for hole injection at the ITO/organic interface is reduced. The Impedance spectroscopy measurement of the devices with the $CF_4$ plasma treatment on the surface of ITO anodes shows change of values in parallel resistance ($R_p$) and parallel capacitance ($C_p$).