• Title, Summary, Keyword: Impedance

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Early Detection of Intravenous Infiltration Using Multi-frequency Bioelectrical Impedance Measurement System: Pilot Study

  • Kim, Jaehyung;Shin, Beumjoo;Jeon, Gyerok
    • Journal of information and communication convergence engineering
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    • v.15 no.2
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    • pp.123-130
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    • 2017
  • The early detection of intravenous (IV) infiltration is necessary to minimize the injury caused by the infiltration, which is one of the most important tasks for nurses. For detecting early infiltration in patients receiving invasive vein treatment, bioelectrical impedance was measured using multi-frequency bioelectrical impedance. The impedance decreased significantly at infiltration, and then decreased gradually over time after infiltration. The relative impedance at 20 kHz decreased remarkably at infiltration, and then gradually decreased thereafter. In addition, the impedance ratio increased temporarily at infiltration and then gradually decreased over time. Furthermore, the impedance at each frequency decreased quantitatively over time. This indicates that IV solution leaking from the vein due to infiltration accumulates in the subcutaneous tissues. Moreover, slopes of log Z vs. log f differently decreased with increasing log f, indicating that the impedance exhibits different responses depending on the frequency.

Advances and challenges in impedance-based structural health monitoring

  • Huynh, Thanh-Canh;Dang, Ngoc-Loi;Kim, Jeong-Tae
    • Structural Monitoring and Maintenance
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    • v.4 no.4
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    • pp.301-329
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    • 2017
  • Impedance-based damage detection method has been known as an innovative tool with various successful implementations for structural health monitoring of civil structures. To monitor the local critical area of a structure, the impedance-based method utilizes the high-frequency impedance responses sensed by piezoelectric sensors as the local dynamic features. In this paper, current advances and future challenges of the impedance-based structural health monitoring are presented. Firstly, theoretical background of the impedance-based method is outlined. Next, an overview is given to recent advances in the wireless impedance sensor nodes, the interfacial impedance sensing devices, and the temperature-effect compensation algorithms. Various research works on these topics are reviewed to share up-to-date information on research activities and implementations of the impedance-based technique. Finally, future research challenges of the technique are discussed including the applicability of wireless sensing technology, the predetermination of effective frequency bands, the sensing region of impedance responses, the robust compensation of noise and temperature effects, the quantification of damage severity, and long-term durability of sensors.

Studies in Impedance Audiometry on Children Less Than 6 Years Old (유소아의 impedance audiometry에 관한 고찰)

  • Oh, Pyung;Kim, Sung-Hak;Song, Jae-Woo;So, Jin-Myung
    • Proceedings of the KOR-BRONCHOESO Conference
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    • pp.4.3-4
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    • 1977
  • Since the clinical application of Impedance measurment by Metz in 1946. Many scholars carried out investigations. Brooks reported on the clinical studies of Impedance on 1053 children, Jerger evaluated on 398 children less than 6 years old, and Cooper studied on the abbreviated screening technic for school children. In Korea, Seoul National University Medical School reported on the experimental studies of Impedance with Madsen acoustic bridge (20~70) on 1976, and we reported on the clinical evaluation on 1023 school children aged between 7~14 with Teledyne Impedance bridge on 1976. This paper is dealt with the studies of Impedance bridge as 110 of children less than 6 years.

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Impedance Measurement and Matching Technique for Medium-Voltage Powerline Communication (고압전력선 통신을 위한 임피던스 측정 및 정합 방안 연구)

  • 이재조;유정훈;홍충선;이대영
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.53 no.5
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    • pp.345-352
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    • 2004
  • Currently, high data rate PLC(Power Line Communications), up to 100 Mbps, which use frequency bandwidth between 2 MHz and 30 MHz is investigated very hard, and commercial PLC modem for low voltage powerline network (indoor) is coming soon into communication market. For the purpose of developing a fit communication system which has little distortion of signal and attenuation, it is surely necessary to know about channel environments of powerline. Especially, the impedance measurement of the powerline and impedance matching are very important. As is known, since medium-voltage powerline (22.9 ㎸) is still working, it is not so simple to measure the powerline impedance. In our study, a portable impedance measurement equipment is developed. It consists of coupling capacitor, a drain coil and impedance matching transformer. The equipment is easily connected to medium voltage line and impedance of power line is measured using a network analyzer. Also, measurement results are used for impedance matching of PLC signal. In fact, matching transformer with several different impedances are used. The matching transformer is connected between coupling capacitor and signal port. In this paper, the developed portable impedance measurement equipment and impedance measurement results are presented. Also impedance matching technique using matching transformers will be explained. We showed the result of the improved performance by the impedance matching.

Body Impedance Measurements for edematous patients (부종환자에서 임피던스를 이용한 수분변화의 예측)

  • 오중환
    • The Korean Journal of Thoracic and Cardiovascular Surgery
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    • v.28 no.11
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    • pp.973-976
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    • 1995
  • The assessment method of human body composion by bioelectrical impedance is very simple, safe, rapid and noninvasive. Based on prediction formulas for total body water from bioelectrical impedance, the observed weight loss should be associated with an increase in impedance. However in edematous patients for dialysis, the calculated total body water loss as calculated from impedance were overestimated and significantly higher than the weight loss after dialysis. So determination of impedance were made in 50 edematous patients before, during and after dialysis. Mean weight loss, which was assumed to be only loss of water was 1719$\pm$ 866 gr and mean impedance change was 71.0 $\pm$ 23.0 Ohm under 50kHz. Body weight loss was highly correlated [r>0.81 with the increase in body impedance under variable frequencies[1, 10, 20, 30, 40, 50 kHz . But there were no differences between frequences. In conclusion, clinical application of bioelectrical impedance method is useful for individual edematous patients with new correlation equation[Y=230+26.8X, X;Impedance change, Y;Calculated total body water loss .

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Temperature effect on wireless impedance monitoring in tendon anchorage of prestressed concrete girder

  • Park, Jae-Hyung;Huynh, Thanh-Canh;Kim, Jeong-Tae
    • Smart Structures and Systems
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    • v.15 no.4
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    • pp.1159-1175
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    • 2015
  • In this study, the effect of temperature variation on the wireless impedance monitoring is analyzed for the tendon-anchorage connection of the prestressed concrete girder. Firstly, three impedance features, which are peak frequency, root mean square deviation (RMSD) index, and correlation coefficient (CC) index, are selected to estimate the effects of temperature variation and prestress-loss on impedance signatures. Secondly, wireless impedance tests are performed on the tendon-anchorage connection for which a series of temperature variation and prestress-loss events are simulated. Thirdly, the effect of temperature variation on impedance signatures measured from the tendon-anchorage connection is estimated by the three impedance features. Finally, the effect of prestress-loss on impedance signatures is also estimated by the three impedance features. The relative effects of temperature variation and prestress-loss are comparatively examined.

New Techniques for Impedance Characteristics Measurement of Islanded Microgrid based on Stability Analysis

  • Hou, Lixiang;Zhuo, Fang;Shi, Hongtao
    • Journal of Power Electronics
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    • v.16 no.3
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    • pp.1163-1175
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    • 2016
  • In recent years, microgrids have been the focus of considerable attention in distributed energy distribution. Microgrids contain a large number of power electronic devices that can potentially cause negative impedance instability. Harmonic impedance is an important tool to analyze stability and power quality of microgrids. Harmonic impedance can also be used in harmonic source localization. Precise measurement of microgrid impedance and analysis of system stability with impedances are essential to increase stability. In this study, we introduce a new square wave current injection method for impedance measurement and stability analysis. First, three stability criteria based on impedance parameters are presented. Then, we present a new impedance measurement method for microgrids based on square wave current injection. By injecting an unbalanced line-to-line current between two lines of the AC system, the method determines all impedance information in the traditional synchronous reference frame d-q model. Finally, the microgrid impedances of each part and the overall microgrid are calculated to verify the measurement results. In the experiments, a simulation model of a three-phase AC microgrid is developed using PSCAD, and the AC system harmonic impedance measuring device is developed.

A Design and Implementation of Position Based Impedance Controller with Self-Adjusted Impedance Parameters (임피던스 파라미터의 자기 조절 기능을 갖는 위치 기반 임피던스 제어기의 설계 및 적용)

  • 황인호;박영칠
    • 제어로봇시스템학회:학술대회논문집
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    • pp.410-410
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    • 2000
  • Impedance control is recognised as one of the most proper control scheme to carry out the assembly tasks, since it can control the dynamic relationship between the manipulator and environment directly. However, it is well known that the contact force cannot be controlled directly using the impedance control. Also impedance parameters should be properly defined depending on the task to be performed. We propose a new position based impedance control, which has self-adjusted impedance parameters and can control the contact force explicitly, Impedance parameters, as time-varying parameters, are adjusted automatically based on the measured contact force and the position error during the task. A proposed algorithm was implemented on the peg-in-hole task with the industrial manipulator. We shows the effectiveness of proposed control method experimentally.

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Impedance Audiometry in Children (학동기 아동의 Impedance Audiometry에 대한 연구)

  • 소진명;전승하;장혁순
    • Proceedings of the KOR-BRONCHOESO Conference
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    • pp.4.2-4
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    • 1979
  • Since Metz had employed the impedance audiometry in 1946, scholars have carried out many investigation. Brook, Jeger, Cooper reported and evaluated the clinical studies of impedance audiometry and its screening test. Recently, in Korea, a studies of impedance audiometry have been reported. We analysed 100 children aged between 7-16 years old who visited OPD of E.N.T. department with the complaints of the nasal obstruction and hard of hearing from Nov. 77-Feb. 79. Through the use of otoscope and impedance audiometry, we evaluated the types of tympanogram, static compliance and the acoustic reflex. This paper is dealing with the statistical study of impedance audiometric result and its literature.

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Design of Channel Impedance Measurement Equipment for Indoor Power Line Communications (옥내 전력선 통신 채널 임피던스 측정 장치 설계)

  • Heo, Yun-Seok
    • The Journal of Information Technology
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    • v.8 no.3
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    • pp.25-33
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    • 2005
  • This paper describe a method for measuring line impedance as a function of frequency for an energized powerline in normal operation. A small sinusoidal signal of a powerline communication utility frequency 30khz$\sim$1Mhz band is continuously injected into the line, and a implemented impedance analyzer calculates the indoor powerline channel impedance from the measured magnitude and phase of resulting voltage and current. The impedance measurement is executed over a range of frequencies to produce a wideband impedance versus frequency characteristic. Implemented impedance analyzer can analysis powerline communication environments measuring line impedance due to load caused in indoor. And measured analysis information through the database can use to evaluate performance of modem and to decide test environment standard.

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