• Title/Summary/Keyword: Impedance Measurement

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Measurement of Grip and Feed Force in the Evaluation of Hand-arm Vibration (수완계 진동 평가에 영향을 미치는 작용력의 측정)

  • 최석현;장한기
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.1038-1042
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    • 2003
  • In order to evaluate dynamic impedance of a hand-arm system it is necessary to measure the hand-transmitted vibration and the reaction force at the same time while gripping the vibrating handle. In the study a device was developed to measure both the vibration and the force. The device consists of a measurement handle with four strain gauge and two accelerometers and a PC based control system with a program for the signal processing and evaluation of the hand-transmitted vibration and reaction force. The handle was installed on the vibration shaker so that it can move by the generated signal from the control system. As an application of the system dynamic reaction force and the frequency weighted acceleration at the handle attached to the shaker were measured at various grip force and feed force. This system will be very useful in the area of impedance measurement and the evaluation of performance of anti-vibration gloves.

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Relative Measurement of Differential Electrode Impedance for Home Healthcare Device (Home Healthcare 장치를 위한 차동 전극 임피던스의 상대적인 측정)

  • Woo, Y.J.;Yoo, S.K.
    • Proceedings of the KIEE Conference
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    • 2007.10a
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    • pp.469-470
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    • 2007
  • In this paper, we propose a simple and relative electrode contact monitoring method. By exploiting the power line interference, which is regarded as one of the worst noise sources for bio-potential measurement, the relative difference in electrode impedance can be measured without a current or voltage source. Substantial benefits, including no extra circuit components, no degradation of the body potential driving circuit, and no electrical safety problem, can be achieved using this method. Furthermore, this method can be applied to multi-channel isolated bio-potential measurement systems and home health care devices under a steady measuring environment.

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Fabrication of Micro-Channel with Embedded Electrode for Impedance Measurement (임피던스 측정용 측벽전극 내장형 마이크로채널 제작)

  • Kang, Gil-Hwan;Roh, Yong-Rae;Kim, Gyu-Man
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.5 no.3
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    • pp.11-16
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    • 2006
  • A new method to fabricate metal electrodes on side wall of the microchannel is presented. Electrical signal can be measured by the metal electrodes on channel side wall when microparticles pass through a polymer microchannel. 3 dimensional metal electrodes on channel side wall could be fabricated by local deposition of metal through a shadowmask and inclined evaporation. The polymer microchannel with side wall electrodes could be precisely aligned onto metal contact patterns on pyrex glass. The impedance measurement test showed possibility of electrical signal measurement using the fabricated device.

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Fabrication of High Precision Pre-amplifier for EEG Signal Measurement and Development of Auto Classification System (뇌파신호 측정을 위한 고성능 전치증폭기 제작 및 자동 신호분류 시스템 개발)

  • 도영수;장긍덕;남효덕;장호경
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.11a
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    • pp.409-412
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    • 2000
  • A high performance EEG signal measurement system is fabricated. It consists of high precision pre-amplifier and auto identification bandwidth unit. High precision pre-amplifier is composed of signal generator, signal amplifier with a impedance converter, body driver and isolation amplifier. The pre-amplifier is designed for low noise characteristics, high CMRR, high input impedance, high IMRR and safety, Auto identification bandwidth unit is composed of AD-converter and PIC micro-controller for real time processing EEG signal. The performance of EEG signal measurement system has been shown the classified bandwidth through the clinical demonstrations.

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Measurement of Acoustic Properties and Prediction of Acoustic Performance of Porous Woven Hoses for Engine Intake Systems (엔진 흡기계에 쓰이는 다공형 직조관의 음향특성 측정 및 성능예측)

  • Park, C.M.;Ih, J.G.;Nakayama, Y.;Kitahara, S.;Takao, H.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.11a
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    • pp.182-186
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    • 2000
  • The porous woven hose is recently considered as an effective element of automotive intake systems. In order to predict the acoustic performance of an intake system with a porous woven hose, the information on the acoustic wall impedance is required. In this article, a measurement technique that is valid over the low frequency range and without mean flow condition is presented. The measurement is performed in a cylindrical chamber with a concentric layout of the sample and the resistance is estimated from measured reactance and transmission loss data. It is observed that the measured transmission loss for a porous woven hose with an arbitrary length agrees well with the predicted one that uses the estimated impedance for a small sample length.

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Liquid Film Thickness Measurement by An Ultrasonic Pulse Echo Method (초음파 Pulse-echo 방법에 의한 액체막 두께 측정)

  • Jong Ryul Park;Jong-Ryul Park;Se Kyung Lee
    • Nuclear Engineering and Technology
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    • v.17 no.1
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    • pp.25-33
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    • 1985
  • The main purpose of this work is to investigate the effects of the wall thickness, the ultrasonic frequency, and the acoustic impedance of wall material on the liquid-film thickness measurement by an ultrasonic pulse echo method. A series of liquid-film thickness measurements in a horizontal air-water stratified system was performed employing a plate-type and a tube-type test sections. Measurements were repeated changing (1) the wall thickness of the test section and (2) the transducer frequency. Also, in an effort to improve the accuracy of the measurement and to exam me the effect of acoustic impedance of wall material on the measurement by an ultrasonic technique, two different stand-off rods, one made of stainless steel and the other polyacrylate, were used in the liquid-film thickness measurement. These experimental results are discussed and compared with the actual film thicknesses.

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Analysis of the Grounding Impedance of a Ground Rod Considering the Frequency-Dependent Resistivity and Relative Permittivity of Soil (토양의 저항률 및 비유전율의 주파수의존성을 고려한 접지봉의 접지임피던스의 해석)

  • Ahn, Chang-Hwan;Choi, Jong-Hyuk;Lee, Bok-Hee
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.26 no.1
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    • pp.54-60
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    • 2012
  • When the transient current with high frequency components such as lightning surges are injected the grounding electrodes, the performance of grounding electrodes should be evaluated as grounding impedance. It is restricted to analyze the grounding impedance by measurement approach since the grounding impedance is very different with the shape and size of grounding electrodes, resistivity and relative permittivity of soil and the frequency component of the injected current. So a variety of simulation approaches have been developed. Typically, the soil resistivity measured with low frequency and relative permittivity between 1 and 80 are used for simulation of the grounding impedance. However, the resistivity and relative permittivity of soil are changed with frequency of injected current. In this paper, the frequency-dependent resistivity and relative permittivity of soil are measured and these parameters are reflected in the simulation of the grounding impedance of a ground rod. The simulated results are compared with the measured results. As a result, the simulated results with frequency-dependent soil parameters show capacitive aspect like measured results in the frequency of lower than 100[kHz] and they are more consistent with the measured results in wide frequency range.

Experimental Study of the In-Water Radiation Impedance of the Finite Baffle Cylinder Radiator (유한 배플 원통 진동체의 수중 방사 임피던스에 대한 실험적 연구)

  • Kim, Won-Ho;Yoon, Jong-Rak
    • The Journal of the Acoustical Society of Korea
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    • v.13 no.2
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    • pp.23-29
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    • 1994
  • In this paper, the measured in-water radiation impedance of cylindrical piezoelectric radiator with finite baffle is compared to the existing theoretical result of that with infinite baffle and the effect of baffle on the radiation impedance is examined. Comparision between measurement and theoretical result of radiation impedance shows that the measured radiation impedance tends to be that of the infinite baffle as the baffle length increases. Another finding of the comparision in that the effect of baffle is more dominant in radiation reactance than in radiation resistance. Therefore, for the use of theoretical radiation impedance of infinite baffle on the design of acoustic transducer, the impedance compensation to the baffle length should conducted.

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Evaluation of Errors Due to Earth Mutual Resistance in Measuring Ground Impedance of Vertically-driven Ground Electrode (수직 접지전극의 접지임피던스 측정에서 도전유도에 의한 오차 평가)

  • Choi, Jong-Hyuk;Choi, Young-Chul;Lee, Bok-Hee
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.9
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    • pp.1778-1783
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    • 2009
  • Ground impedance for the large grounding system is measured according to the IEEE Standard 81.2 which is based on the revised fall-of-potential method of installing auxiliary electrode at a right angle. When the auxiliary electrodes are located at an angle of $90^{\circ}$, the ground impedance inevitably includes the error due to earth mutual resistance. In this paper, in order to accurately measure the ground impedance of vertically-driven ground electrodes, error rates due to earth mutual resistance are evaluated by ground resistance and ground impedance measuring devices and compared with calculated values. As a result, the measured results are in good agreement with the computed results considering soil layer with different resistivity. The error rates due to earth mutual resistance decrease with increasing the length of ground electrode in the case that the ratio of the distance between the ground rod to be measured and the auxiliary electrodes to the length of ground electrode(D/L) is same. The ground impedance should be measured at the minimum distance between the auxiliary electrodes that will have an estimated measurement accuracy due to earth mutual resistance.

Measurement method of the signal transfer characteristic(S21) of the impedance transformer (임피던스 변환회로의 신호 전달특성(S21) 측정 방법)

  • Park, Ung-hee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.23 no.10
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    • pp.1282-1289
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    • 2019
  • In order to measure the transfer characteristic(S21) of the impedance transformer, two impedance transformers must be symmetrically connected. However, the transfer characteristic of two symmetrically connected impedance transformers is influenced by the length of the intermediate connection line. This paper theoretically examines closely the length of the intermediate connection line to obtain the accurate transfer characteristic of the impedance transformer. The electrical length of the intermediate connection line for obtaining the accurate transfer characteristic of the 4:1(50-Ω:12.5-Ω) impedance transformer is calculated about 45°. Using the calculated length of the connection line, The λ/4-microstrip impedance transformer is fabricated at 1 GHz to measure the transfer characteristic. The symmetrically connected impedance transformer is measured the reflection characteristic(S11) of -40.64dB and the transfer characteristic(S21) of -0.154dB at 0.980GHz. This value is approximately equal to the theoretical calculated 987MHz center frequency and -0.15dB transfer loss value of the λ/4-microstrip impedance transformer.