• Journal of Electrical Engineering and information Science
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• v.2 no.5
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• pp.60-64
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• 1997

The design process and construction method of a strip line is described for measuring radiated susceptibility of vehicular components having electrical cables more than 2 min length. he characteristic impedance of the trip line was determined 90$\Omega$ to obtain the field uniformity of $\leq$${\pm}$3 dB in the frequency range from 100 kHz to 500 MHz. Tapered coaxial lines were used instead of the traditional lumped circuit element for the impedence matching units, therefore, the strip line has high power capability. Using these techniques, the field uniformity and power capability of a strip line could be considerably improved.

• International Journal of Internet, Broadcasting and Communication
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• v.16 no.3
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• pp.228-235
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• 2024

Battery use is increasing worldwide to achieve carbon neutrality and improve energy efficiency, but batteries are a finite resource and their application is determined by capacity and specifications. Battery performance deteriorates as the number of uses increases. A certain level of battery performance degradation has become an issue in the field of reuse and recycling, and various studies are being conducted on reuse to solve power shortages. Waste batteries from electric vehicles are suitable for building ESS based on reusable batteries, and for stable use, technical skills are needed to accurately predict battery life and determine status information. Predicting battery life and determining status information are difficult due to non-linearity due to internal structure or chemical changes. In this paper, we manufactured a modular internal resistance measuring device and compared the measured values with Hioki equipment to minimize the error rate through a correction method. As a result of testing Hioki equipment and modular measuring instruments to ensure efficiency and safety based on reusable batteries, an accuracy of over 95% was confirmed.

• Journal of Sensor Science and Technology
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• v.7 no.4
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• pp.293-299
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• 1998

An objective of this study is to develop a voltage measuring device that uses a gas-filled switch (GS) on 22.9 kV-y extra-high voltage distribution lines. The voltage measuring device proposed in this paper is a kind of capacitive divider which consists of a detecting electrode attached outside of the bushing of GS, an impedance matching circuit, and a voltage buffer. It can be easily installed in an established GS without changing the structure. For the calibration and application investigations, the voltage measuring device was set up in the 25.8 kV 400 A GS, and a step pulse generator having 5 ns rise time is used. As a result, it was found that the frequency bandwidth of the voltage measuring device ranges from 1.35 Hz to about 13 MHz. The error of voltage dividing ratio which is evaluated by the commercial frequency voltage of 60 Hz was less than 0.2%. In addition, voltage dividing ratio in the commercial frequency voltage and in a non-oscillating impulse voltage were compared, and their deviation were less than 0.7%.

• Tribology and Lubricants
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• v.27 no.3
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• pp.125-133
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• 2011

The purpose of this study is to develop an engine oil quality monitoring system to warn the abnormal condition of engine oil. To do this, first of all, it is needed a personal controller development to measure the capacitance of a pre-developed engine oil deterioration detection sensor integrated with an oil filter. To measure the capacitance of engine oil in the sensor, it is used the way measuring the electric charging time in a capacitor by impressing DC volt. This method has merits on cost and signal stability. The measured capacitance is compensated by comparing with the one measured by an impedance analyzer. Also, using the dielectric constant gained by an impedance analyzer, the calculating equation of the dielectric constant of engine oil related with the currently developed sensor is decided. Then, the deterioration degree of engine oil is estimated according to the change rate of dielectric constant between green oil and used oil. Finally, using this dielectric constant information together with engine oil temperature and pressure, the currently developed engine oil quality monitoring system is to tell the abnormal state of engine oil.

• Journal of KSNVE
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• v.8 no.6
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• pp.1137-1143
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• 1998

This paper describes the method to measure of the vibrational power transmitted from the vibration source to the supporting structure in the horizontal direction. Generally, it is impossible to measure horizontal forces at the coupling points. However. the vibrational Power transmitted in the horizontal direction can be measured by using indirect method that is based on the mechanical impedance and velocities at the coupling points. We proposed the method to estimate the vibrational power when the vibration source and supporting structure cannot be separated. In this paper. the vibrational power transmitted in the horizontal direction is also estimated by using this method. The estimated and measured results of the mobilities at the coupling point and vibrational power in the horizontal direction are compared. It is shown that the estimated results agree well with the measured results. For the supporting structure with multiple coupling points, the other coupling points should be considered for measuring the vibrational power transmitted through one coupling points. We examine the effects of other coupling points and measure the vibrational power without considering the other coupling points.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1453-1459
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• 2015

Loss of excitation (LOE) relay is prevalently used to protect synchronous generator. The widely used method for synchronous generator LOE protection is a negative offset mho relay with two zones. The basis of this relay is identical to mho impedance relay. In other words, this relay calculates impedance by measuring voltage and current at the generator terminal. On the other hand, the presence of series compensation, changes measured voltage and current signals during loss of excitation. This paper reveals that the presence of series compensators such as fixed series capacitors (FSCs) and static synchronous series compensator (SSSC) causes a significant delay on the performance of generator LOE relay. It is also shown that the presence of SSSC causes the LOE relay to be under-reached. Different operating modes of the power system, the SSSC and also different percentages of series capacitive compensations have been considered in the modeling. All the detailed simulations are carried out in the MATLAB/Simulink environment using the SimPowerSystems toolbox.

• Journal of KSNVE
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• v.1 no.2
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• pp.121-128
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• 1991

In order to use viscoelastic materials efficiently for noise and vibration control, or th qualify newly developed materials, knowledge of the Young' s modulus and loss factor is essemtial. These material properties, the so-called complex Young' s modulus, are frequently treated as dynamic charicteristics because of their dependence upon the frequency. Many techniques have been developed and verified for measuring complex Young' s modulus of viscoelastic materials. Among them, the impedance method is preferable in order to obtain the frequency information in detail. In this method, a cylindrical or prismatic specimen is excited into longitudinal harmonic vibration at one end, the other being fixed, and the resulting force is measured at the driving or fixed end. The amplitude ratio of the two signals and phase angle between them are then used to compute the material properties using various mathematical models. In this paper, the impedance method is investigated theoretically and experimentally. A way to determine the specimen geometry which is most appropriate for the identification of complex Young' s modulus using the lumped mass model is presented and discussed. Then experimental results supporting the theoretical predictions are presented.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.207-207
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• 2008

Modern industry has focused on processing that produce low- loss dielectric substrates used complex micron-sized devices using tick film technologies such as tape casting and slip casting. However, these processes have inherent disadvantages fabricating high density interconnect with embedded passives for high speed communication electronic devices. Here, we have successfully fabricated porous alumina dielectric layer infiltrated with polymer solution by using inkjet printing process. Alumina suspensions were formulated as dielectric ink that were optimized to use in inkjet process. The layer was confirmed by field emission scanning electron microscope (FE-SEM) for measuring microstructure and volume fraction. In addition, the reaction kinetics and electrical properties were characterized by FT-IR and the impedance analyzer. The volume fraction of alumina in porous dielectric alumina layer is around 70% much higher than that in the conventional process. Furthermore, after infiltration on the dielectric layer using polymer resins such as cyanate ester. Excellent Q factors of the dielectric is about 200 when confirmed by impedance analyzer without any high temperature process.

• Journal of Hydrogen and New Energy
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• v.1 no.1
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• pp.48-54
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• 1989

Semiconductive property of the passivating $TiO_2$ film was investigated by measuring the impedance of passivated titanium electrode in a 0.1 N NaOH solution. The passive film was prepared galvanostatically with $10mA/cm^2$ at formation potential of 50 V in a 1 N $H_2SO_4$ solution. The impedance measurement was conducted by superimposing an ac voltage of 5 m V amplitude with the frequency ranging from 5 to 10000 Hz on a dc bias (applied potential). The donor distribution in the film was depicted from the analysis of the non-linear slope of Mott-Schottky plot. The region with nearly constant concentration of donors near the electrolyte/film interface amounts at about 60 percent of the total film thickness and donor concentration increases largely with distance from the surface in an inner region near the film/metal interface. In a region of the film/metal interface the donor concentration showed a frequency dependence greater than in a region of the electrolyte/film interface. The result of donor concentration against frequency suggests a transition from crystalline to amorphous state with distance from the electrolyte/film interface in the passivating $TiO_2$ films. This is also confirmed by the ac conductivity measurement.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.181-181
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• 2012

The microwave probe for measuring plasma density is widely used for its advantages: First, it is not affected by the reactive gas. Second, it can measure local plasma parameters such as plasma density, plasma potential and plasma temperature. Third, it is simple and robust. A cut-off probe is the one of the most promising microwave probe. Recently, Kim et al. reveals the physics of the cut-off probe but the effect of the sheath on the determination of the plasma density is not explained. In this presentation, for taking account of sheath effects on determination of plasma density from the cut-off peak, a simplified circuit modeling and an E/M simulation are conducted. The results show that occupation ratio of sheath volume between two tips of the cut-off probe and subsequence pressure condition mainly change position of the cut-off peak with respect to plasma frequency. Magnitude of relative voltage taken on the impedance of sheath and the impedance of bulk plasma can explain this effect. Furthermore, effects of gap size, tip radius, and tip length ware revealed based on above analysis.