• Journal of Sensor Science and Technology
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• v.25 no.1
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• pp.1-7
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• 2016

Bioelectrical impedance (BI) at popliteal regions was measured using a bioelectrical impedance measurement system (BIMS), which employs the multi-frequency and the two-electrode method. Experiments were performed as follows. First, a constant AC current of $800{\mu}A$ was applied to the popliteal regions (left and right) and the BI was measured at eight different frequencies from 10 to 500 kHz. When the applied frequency greater than 50 kHz was applied to human's popliteal regions, the BI was decreased significantly. Logarithmic plot of impedance vs. frequency indicated two different mechanisms in the impedance phenomena before and after 50 kHz. Second, the relationship between resistance and reactance was obtained with respect to the applied frequency using BI (resistance and reactance) acquired from the popliteal regions. The phase angle (PA) was found to be strongly dependent on frequency. At 50 kHz, the PA at the right popliteal region was $7.8^{\circ}$ slightly larger than $7.6^{\circ}$ at the left popliteal region. Third, BI values of extracellular fluid (ECF) and intracellular fluid (ICF) were calculated using BIMS. At 10 kHz, the BI values of ECF at the left and right popliteal regions were $1664.14{\Omega}$ and $1614.08{\Omega}$, respectively. The BI values of ECF and ICF decreased sharply in the frequency range of 10 to 50 kHz, and gradually decreased up to 500 kHz. Logarithmic plot of BI vs. frequency shows that the BI of ICF decreased noticeably at high frequency above 300 kHz because of a large decrease in the capacitance of the cell membrane.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.3
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• pp.259-268
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• 2014

In this paper, we suggest a method of extracting circuit parameters of the insulating transformer using S-parameter measurement, especially in high frequency range. At 60 Hz, conventionally, no load test and short circuit test are used to extract the circuit parameters. In this paper S-parameters measured from VNA(Vector Network Analyzer) were used to extract the transformer parameters using data fitting method (optimization). The S-parameters from the equivalent circuit using the extracted parameters showed good agreement with those from measurement. Furthermore, the transformer secondary voltages from the equivalent circuit model also coincide quite exactly to the measured secondary voltages in sinusoidal forms. Finally we assert that the proposed method to extract the parameters for the insulating transformer using S-parameter is valid especially in high frequency.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.388-390
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• 1997

We describe the characteristic of LVI(Low-voltage Impulse) test system and methods to detect the deformation of windings in the power transformers. Any winding deformation will result in a change of capacitance between winding parts and possibly some change in the winding inductance. These changes will then result in a change in the responce to the applied pulse in both the magnitude and period of the resulting oscillations. A results of measured differential method in stead of typical method, the sensitivity is greatly improved by the use of differential methods where the pulse is applied to two identical windings and the response measured with a differential amplifier.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.346-349
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• 1988

Conductance technique is the moat accurate method and gives more detailed information about interface of the MIS structure than other methods. With the measurement of the equivalent parallel conductance and capacitance, the characterization of Si-SiN interface is developed. The interface state density of Si-SiN is obtained by $8{\times}10^{11}$ - $6{\times}10^{12}(eV^{-1}cm^{-2}$). After the positive B-T stress is performed on the sample, the interface state density gets increased. The interface state density is not effected by the D.C. stress.

• Journal of the Korean Chemical Society
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• v.20 no.2
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• pp.129-135
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• 1976

A direct-reading conductance measuring system using a potentiostatic circuit and a four-electrode conductance cell was devised. The difficulties with the traditional method of using the Wheatston bridge and a two-electrode cell due to the complicated nature of the electrochemical system, the double layer capacitance and the Faradaic impedance at the electrodes, etc., could be avoided in this method. The devised instrument proved to be convenient and suitable for precise measurements. The results of measured conductivities of KCl and HCl solutions are reported.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.59-60
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• 2021

The unit-water content has a major problem in concrete structures which leads to micro cracks on the concrete during drying time. Thus, the compressive strength and durability of the concrete structures are significantly reduced. Several techniques have been developed to measure the unit-water content in concrete structures such as heating drying, unit volume mass, and capacitance measurements. However, these techniques have problems in during measurement such as longer time, expensive and difficult in analysis of data. Frequency Domain Reflectivity (FDR) is one of the sensors which used to measure the water content. This method has several advantages including easy to measure, inexpensive, and capable of measuring moisture in real time. In this study, an attempt has been made to evaluate the unit-water content in concrete using the FDR sensor and interpret the data with deep learning method.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.109-110
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• 2022

Currently, interest in the quality of concrete is increasing. Among the important factors for evaluating the quality of concrete, interest in unit-water content is also increasing. Currently, the air-meter method, the microwave oven drying method, the capacitance method, and the microwave penetration method are used to measure the unit-water content of concrete.. Among the above methods, except for the microwave method, the measurement method is complicated, portability is reduced, and economic efficiency is reduced. This research aims to measure a unit-water content by using a Frequency Domain Reflectometry(FDR) sensor that is economical, simple to measure, and portable among microwave methods. In addition, it is an experimental study to determine the accuracy of unit-water content using a single input residual model during deep learning to solve the limitations of the FDR sensor.

• Korean Journal of Acupuncture
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• v.26 no.3
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• pp.1-11
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• 2009

Objectives : The object of this study is to investigate the balance/imbalance of skin capacitances between left and right meridians, and to analyze the change patterns of electric energy on meridians with the lapse of time. Method : Electric potential was measured on five source points (LU9, PC7, HT7, LI4, SI4) bilaterally for 4 hours. The energy balance/imbalance between left and right was investigated, and the change patterns with time were analyzed. Results and Conclusions : The amplitude of meridian energy on five source points and the energy balance/imbalance between left and right were varied in each individual. When a source point showed a balanced meridian energy bilaterally, the change patterns of meridian energy with time were similar between left and right. While, when it showed an imbalanced energy between left and right, the change patterns of meridian energy were also different between left and right. Through this study, we proposed a new diagnostic method of meridian energy.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.5 s.347
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• pp.25-33
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• 2006

We have extracted the material parameters such as absorption coefficients of GaN, $Al_{0.2}Ga_{0.8}N$, and Schottky contact metal Ni of Schottky Diode UV-A and B detectors using a transfer matrix method (TMM). The ratios of the absorbed light to the total incident amount at the depletion regions of GaN and $Al_{0.2}Ga_{0.8}N$ have been calculated in order to obtain the spectral responsivity. Absorption coefficients of the materials have been obtained by fitting the simulated data with measured data. The depletion layer thickness has been obtanied by capacitance-voltage measurement. The results pave the way for the optimum design of UV Schottky detectors. Since the absorption coefficient of the Ni electrode is very high, its thickness is a major factor that determines the responsivity. It is possible to attain improved UV detectors using thinnest possible Ni electrodes and wide depletion regions of GaN and $Al_{0.2}Ga_{0.8}N$.

• Journal of Sensor Science and Technology
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• v.10 no.4
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• pp.266-272
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• 2001

A coil-type capacitive sensor on which the deterioration of the car engine oil can be in situ measured, has been developed. The sensor was designed to get over 10 pF at the limited space on the drain hole of the oil pan. The design factors for stable capacitance measurement such as coil diameter and winding condition, materials and configuration of the coil former, and shielding method, etc., were known by both computer simulation and experimental investigations. The dielectric properties measured by several sensors for an used sample oil were consisted within 0.25%. The sensor installed on the car having severe vibration, temperature and humidity fluctuation, even electromagnetic noise, has shown very distinguishable results.