• 제목/요약/키워드: electrical impedance

검색결과 2,489건 처리시간 0.028초

생체 임피던스 방법을 이용하여 복압을 측정하기 위한 최적 전극위치 선정 (Optimum Electrode Selection for Measuring Abdominal Pressure using Bio-Impedance Method)

  • 김거식;이상옥;서정환;김경섭;송철규
    • 전기학회논문지
    • /
    • 제56권7호
    • /
    • pp.1339-1342
    • /
    • 2007
  • In this study, we determined the optimum electrode pair for measuring the abdominal pressure using bio-impedance method and compared with conventional methods. Because impedance changes differ from a weight, a height, contractile force, volume of muscle and blood other or whatever of individuals, it was quantified using values of impedance change, correlation coefficient and SNR. Our results showed the optimum electrode pair (1, 9) which could detect impedance changes due to an increase of the intensity of the abdominal pressure. The correlation coefficient and quadratic function between the RMS values of EMG and the impedance changes were 0.87 and $y=0.0014x^2+0.0620x+0.6958$, respectively. It demonstrated that the abdominal pressure could be measured noninvasively and simply using bio-impedance method. We propose that this optimum electrode configuration would be useful for future studies involving the convenient measurement of abdominal pressure by ambulatory urodynamics monitoring study.

A Study on a Catenary Impedance Estimation Technique using Boosting Current Compensation Based on Current Division Characteristics of an AT Feeding System

  • Jung, Hosung;Kim, Hyungchul;Chang, Sang-Hoon;Kim, Joorak;Min, Myung-Hwan;An, Tae-Pung;Kwon, Sung-Il
    • Journal of Electrical Engineering and Technology
    • /
    • 제10권3호
    • /
    • pp.1370-1376
    • /
    • 2015
  • Generally, an autotransformer(AT) feeding system consists of double tracks, up and down, with the trolley wire and feeder wire of the up and down tracks connected in the sectioning post(SP). Consequently, load current or fault current flows on two tracks based on catenary impedance characteristics, making it difficult to estimate catenary impedance accurately. This paper presents a technique for the estimation of catenary impedance using boosting current compensation based on the current division characteristics of an AT feeding system to improve the operation performance of impedance relay. To verify the technique, we model an AT feeding system through a power analysis program (PSCAD/EMTDC) and simulate various operation and fault conditions. Through the simulation, we confirmed that the proposed technique has estimated catenary impedance with a similar degree of accuracy to the actual catenary impedance

경락 임피던스 측정 시스템 개발에 관한 연구 (Study on the Development of Meridian Impedance Measurement System)

  • 이우철;인창식;민경기
    • 전기학회논문지
    • /
    • 제58권2호
    • /
    • pp.422-429
    • /
    • 2009
  • Meridian which used as the basic theory of acupuncture treatment, is an important functional connection system of acupuncture point in oriental medicine. Yangdorak and EAV have lack of precision because of using 2-electrode method, occurring high non-uniformed current density and electrode contact status on electrode placement spot. Therefore we implemented a meridian impedance measurement system for measuring meridian impedance using 4-electrode method. In order to confirm the precision of developed system, we made an constant current characteristic experiment using standard resistor. As a results of clinical study with 18 subjects, the meridian impedance showed that reproductivity and repeatability of HT7 acupuncture point are $0.515[k{\Omega}]{\pm}0.000$(mean${\pm}$standard deviation) and $0.515[k{\Omega}]{\pm}0.002$, respectively. And reproductivity and repeatability of PC7 are $0.521[k{\Omega}]{\pm}0.000$ and $0.521[{\Omega}]{\pm}0.001$ respectively. The proposed system was stable and reliable. Therefore this study proved AC impedance method to valid in measuring meridian impedance, and also verified precision and repeatability of the proposed meridian impedance measurement system. The proposed system will serve as more effective method of measuring meridian phenomena as a bioelectric signal in clinical practice.

3상 계통 연계형 인버터의 역상분 전류 주입을 이용한 계통 등가 임피던스 추정 기법 (Equivalent Grid Impedance Estimation Method Using Negative Sequence Current Injection in Three-Phase Grid-connected Inverter)

  • 박찬솔;송승호;임지훈
    • 전력전자학회논문지
    • /
    • 제20권6호
    • /
    • pp.526-533
    • /
    • 2015
  • A new algorithm is proposed for the estimation of equivalent grid impedance at the point of common coupling of a grid-tie inverter output. The estimated impedance parameter can be used for the improvement of the performance and the stability of the distributed generation system. The estimation error is inevitable in the conventional estimation method because of the axis rotation due to PLL. In the conventional estimation error, the d-q voltage and current are used for the calculation of the impedance with active and reactive current injections. Conversely, in the proposed algorithm, the negative sequence current is injected, and then the negative sequence voltage is measured for the impedance estimation. As the positive and negative sequence current controller is independent and the PLL is based on the positive sequence component only, the estimation of the equivalent impedance can be achieved with high accuracy. Simulation and experimental results are compared to validate the proposed algorithm.

봉상접지전극의 접지임피던스의 주파수의존성의 분석 (Analysis of the Frequency Dependent Characteristics of Ground Impedance of a Ground Rod)

  • 이복희;엄주홍
    • 대한전기학회논문지:전기물성ㆍ응용부문C
    • /
    • 제53권8호
    • /
    • pp.426-432
    • /
    • 2004
  • This paper presents a systematic approach of measurement, modeling and analysis of grounding system impedance in the field of lightning protection system and intelligent power equipments. The measurement and analysis system of ground impedance is based on a computer aided technique. The magnitude and phase of ground impedance were determined by the novel measurement and analysis using the revised fall-of-potential method. The ground impedances of the ground rod of 50 m long are considerably dependent on the frequency. The ground impedance is mainly resistive in the frequency range of 3-20 kHz. At higher frequencies, the reactive components of the ground impedances are no longer negligible and the inductance of the ground rod was found to be the core factor deciding the ground impedance. Although the steady-state ground resistance of the ground rod of 50 m was less than that of the ground rod of 10 m, the ground impedances of the ground rod of 50 m over the frequency range of more than 60 kHz were much greater than those of the ground rod of 10 m. Furthermore, the equivalent circuit model based on the measured data was proposed. and the calculated results were in approximately agreement with the measured data.

전극길이 및 펄스반복율에 대한 부하임피던스 특성변화 및 EMTP 해석에 관한 연구 (A Study on the Characteristics of Corona Critical Voltage and EMTP Simulatuon on Increasing Load Impedance and Pulse Repetition)

  • 정종한;송우정;전진안;이유수;김휘영;김희제
    • 대한전기학회:학술대회논문집
    • /
    • 대한전기학회 2002년도 하계학술대회 논문집 C
    • /
    • pp.1850-1852
    • /
    • 2002
  • In this paper, we studies EMTP analysis and characteristics of critical voltage of pulse corona and load impedance on variable electrode length. To obtain a stable Pulse voltage, we designed a compact pulse generator switched MOSFET and tested their characteristics by adjusting electrode length and pulse repetition. As a result, critical voltage of pulse corona and load impedance on increasing electrode length were decreased. These results indicate we can control critical voltage of pulse corona and suppress arc discharging between two electrodes.

  • PDF

신경회로망을 이용한 고저항 고장 검출 (High Impedance Fault Detection Using Neural Networks)

  • 한중길;이화석;윤재영;양광호;박준호
    • 대한전기학회:학술대회논문집
    • /
    • 대한전기학회 1995년도 하계학술대회 논문집 B
    • /
    • pp.465-467
    • /
    • 1995
  • High impedance fault can not be easily detected by conventional method. But if it would not be detected and cleared quickly, it can result in fires, and electric shock. In this paper, ANN, which has learning capability, is used for high impedance fault detection. The potential of the neural network approach is demonstrated by simulation using KEPCO's measured data. Among ANN models used in this paper, CPN shows better result than BPN in respect of convergence and reliability.

  • PDF

Genetic Algorithm Approach to Image Reconstruction in Electrical Impedance Tomography

  • Kim, Ho-Chan;Boo, Chang-Jin;Lee, Yoon-Joon;Kang, Chang-Ik
    • KIEE International Transactions on Electrophysics and Applications
    • /
    • 제4C권3호
    • /
    • pp.123-128
    • /
    • 2004
  • In electrical impedance tomography (EIT), the internal resistivity distribution of the unknown object is computed using the boundary voltage data induced by different current patterns using various reconstruction algorithms. This paper presents a new image reconstruction algorithm based on the genetic algorithm (GA) via a two-step approach for the solution of the EIT inverse problem, in particular for the reconstruction of "static" images. The computer simulation for the 32 channels synthetic data shows that the spatial resolution of reconstructed images in the proposed scheme is improved compared to that of the modified Newton-Raphson algorithm at the expense of an increased computational burden.rden.

온도변화에 따른 유기 발광 다이오드의 전기적 특성 (Electrical Properties of Organic Light-Emitting Diode depending on Varied Temperature)

  • 이동규;오용철;조춘남;김진사;신철기;박건호;이성일;김충혁
    • 한국전기전자재료학회:학술대회논문집
    • /
    • 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
    • /
    • pp.492-493
    • /
    • 2007
  • We have investigated Electrical Properties of Organic Light-Emitting Diode depending on Varied Temperature using 8-hydroxyquinoline aluminum($Alq_3$) as an electron transport and emissive material. We analyzed the electrical properties of organic light emitting diodes by impedance characteristics of ITO/$Alq_3$/Al. Impedance characteristics was measured complex impedance Z and phase e in the frequency range of 40 Hz to $10^7\;Hz$. From these analyses, we are able to interpret electrical Properties of OLED depending on temperature.

  • PDF

리튬배터리의 잔여 유효 수명 추정을 위한 배터리 모듈용 AC 임피던스 스펙트럼 측정장치 (An AC Impedance Spectrum Measurement Device for the Battery Module to Predict the Remaining Useful Life of the Lithium-Ion Batteries)

  • 이승준;파르한 파루크;칸 아사드;최우진
    • 전력전자학회논문지
    • /
    • 제25권4호
    • /
    • pp.251-260
    • /
    • 2020
  • A growing interest has emerged in recycling used automobile batteries into energy storage systems (ESSs) to prevent their harmful effects to the environment from improper disposal and to recycle such resources. To transform used batteries into ESSs, composing battery modules with similar performance by grading them is crucial. Imbalance among battery modules degrades the performance of an entire system. Thus, the selection of modules with similar performance and remaining life is the first prerequisite in the reuse of used batteries. In this study, we develop an instrument to measure the impedance spectrum of a battery module to predict the useful remaining life of the used battery. The developed hardware and software are used to apply the AC perturbation to the used battery module and measure its impedance spectrum. The developed instrument can measure the impedance spectrum of the battery module from 0.1 Hz to 1 kHz and calculate the equivalent circuit parameters through curve fitting. The performance of the developed instrument is verified by comparing the measured impedance spectra with those obtained by a commercial equipment.