• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.75-77
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• 2005

When measuring impedance of electronic component and so on, even the small size can reject the interference to shielding object. But, the interference through human body is grown when measuring bioimpedance without establishing shield specially. Consequently, when measuring bioimpedance in this paper, it proposed impedance measurement method to take advantage of spread spectrum technology, so that can reject the interference without establishing shield specially. Spread spectrum impedance measurement method to propose in this paper can reject the interference signal that occurring from medical instruments in the human body, the interference signal that is flowed in from surrounding environment when measuring impedance. It improved SJR(signal to jamming ratio) about 22dB than conventional method that actually realize and experiment spread spectrum impedance measurement method.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.414-417
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• 2002

This paper describes the possibility of analyzing gait pattern from the variation of the lower leg electrical impedance. This impedance is measured by the four-electrode method. Two current electrodes are applied to the thigh and foot., and two potential electrodes are applied to the lateral aspect, medial aspect, and posterior position of lower leg. We found the optimal electrode position for knee and ankle joint movements based on high correlation coefficient, least interference, and maximum magnitude of impedance change. From such features of the lower leg impedance, it has been made clear that different movement patterns exhibit different impedance patterns and impedance level.

• Smart Structures and Systems
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• v.30 no.5
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• pp.463-477
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• 2022

In this paper, a hybrid vibration-impedance-based damage monitoring approach is experimentally evaluated for prestressed concrete (PSC) structures with local strand breakage. Firstly, the hybrid monitoring scheme is designed to alert damage occurrence from changes in vibration characteristics and to localize strand breakage from changes in impedance signatures. Secondly, a full-scale PSC anchorage is experimented to measure global vibration responses and local impedance responses under a sequence of simulated strand-breakage events. Finally, the measured data are analyzed using the hybrid monitoring framework. The change of structural condition (i.e., damage extent) induced by the local strand breakage is estimated by changes in a few natural frequencies obtained from a few accelerometers in the structure. The damaged strand is locally identified by tomography analysis of impedance features measured via an array of PZT (lead-zirconate-titanate) sensors mounted on the anchorage. Experimental results demonstrate that the strand breakage in the PSC structure can be accurately assessed by using the combined vibration and impedance features.

• Journal of Sensor Science and Technology
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• v.14 no.1
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• pp.33-41
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• 2005

For more convenient electrode-electrolyte interface impedance analysis in biosensor, a stand-alone impedance measurement system is required. In our study, we developed a PC-based portable system to analyze impedance of the electrochemical cell using microprocessor. The devised system consists of signal generator, programmable amplifiers, A/D converter, low pass filter, potentiostat, I/V converter, microprocessor, and PC interface. As a microprocessor, PIC16F877 which has the processing speed of 5 MIPS was used. For data acquisition, the sampling rate at 40 k samples/sec, resolution of 12 bit is used. RS-232 with 115.2 kbps speed is used for the PC communication. The square wave was used as stimuli signal for impedance analysis and voltage-controlled current measurement method of three-electrode-method were adopted. Acquired voltage and current data are calculated to multifrequency impedance signal after Fourier transform. To evaluate the implemented system, we set up the dummy cell as equivalent circuit of which was composed of resistor, parallel circuit of capacitor and resistor connected in parallel and measured the impedance of the dummy cell; the result showed that there exist accuracy within 5 % errors and reproduction within 1 % errors compared to output of Hioki LCR tester and HP impedance analyzer as a standard product. These results imply that it is possible to analyze electrode-electrolyte interface impedance quantitatively in biosensor and to implement the more portable high speed impedance analysis system compared to existing systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.12
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• pp.1084-1096
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• 2016

This paper presents method of design and analysis of a high-speed serial interface connector with a data rate of 12.5 Gbps. A high-speed serial interface connector is composed of various material and complex structures. It is very difficult to match the impedance of each discontinuous portion of connector. Therefore, this paper proposes the structure of a connector line that be simplified a connector. In the structure of proposed connector line, this research presents a method for extracting R, L, C and G parameters, analyzing the differential mode impedance, and minimizing the impedance discontinuity using time domain transmissometry and time domain reflectometry. This paper applies the proposed methods in the connector line to the high-speed serial interface connector. The proposed high-speed serial interface connector, which consists of forty-four pins, is analyzed signal transmission characteristics by changing the width and spacing of the four pins. According to the analysis result, as the width of the ground pin increases, the impedance decreases slightly. And as the distance between the ground pin and the signal pin increases, the impedance increases. In addition, as the width of the signal pin increases, the impedance decreases. And as the distance between the signal pin and the signal pin increases, the impedance decreases. The impedance characteristic of initial connector presents ranges from 96 to $139{\Omega}$. Impedance characteristic after applying the structure of proposed connector is shown as a value between 92.6 to $107.5{\Omega}$. This value satisfies the design objective $100{\Omega}{\pm}10%$.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.7
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• pp.503-507
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• 1999

Quartz crystal in contact with viscoelastic medium was described directly in terms of the electrical equivalent circuit of the system. Stearic acid was used as viscoelastic medium and deposited on the surface of quartz crystal using the Langmuir-Blodgett(LB) method. Impedance properties of quartz crystal coated with LB films which were investigated by using admittance diagram and $Ζ-\theta$ plot a method of impedance analysis. When stearic acid LB film was deposited on the surface of quartz crystal, resonant frequency of quartz crystal was changed about 100 Hz/layer. This result illustrates the ability of the sensor system to detect small amounts of special gas in air.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1089-1090
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• 2006

This paper analyzes impedance convergence characteristics and harmonics of electric locomotives operation and fault condition. To simulate the various fault and operation condition, AT feeding system and various locomotives are modeled using PSCAD/EMTDC. Analysis shows that impedance are converged into protection area in the case of short fault between catenary and rail or catenary and feeder line but in the case of disconnection fault, impedance is rater bigger so protective relay can't detect the fault. Therefore more analysis of overload and high impedance fault caused disconnection fault is needed.

• Journal of Industrial Technology
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• v.27 no.B
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• pp.129-135
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• 2007

In this paper, an modal analysis based on the distribution of the electromagnetic fields on the UWB elliptical patch-slot antenna is presented. We designed the UWB antenna by iterating the dimensional parameters of the antenna as the traditional design method. Then the antenna was carefully analyzed using 3D E-M simulator. The result of the analysis shows that the slot antenna operates on a series of the multi-pole radiations based on TE modes matched to the system impedance. This result gives us an easier method to design the similar antennas, which is the impedance matching to the system impedance after once constructing a proper structure with a series of multi-mode resonances.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.955-958
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• 2005

Bioelectrical Impedance Analysis(BIA) can measure body water amount and then body fat mass. The formula is used here FFM=-4.104+0.518H+0.231W+0.130X+4.229S is used, In this work, H is height, R is resistance value, W is weight, X is reactance and S is distinction of sex.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.689-692
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• 2005

Bioelectrical Impedance Analysis(BIA) can measure body water amount and then body fat mass. Locate 4 electrode in palm to measure efficiently and flow current(50kHz, 800uA) in body for measuring voltage and capacitance. And proposed method to measure body fat with hight, weight, age and distinction of sex.