• Title/Summary/Keyword: Impedance Measurement

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A Study of Flexible T-DMB Antenna Using Rectangular Stub and Matching Circuit (매칭 회로와 구형 Stub를 이용한 Flexible T-DMB 안테나 구현에 관한 연구)

  • Kim, Ho-Jin;Lee, Seon-Hyeon;Lee, Young-Hun;Lee, Sang-Seok
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.22 no.2
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    • pp.236-244
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    • 2011
  • In this paper, we proposed flexible T-DMB dipole-shaped antenna that has strength of glass antenna and also has portability and ease of production. The input impedance of antenna according to vehicle body-effect was considered in order to install the antenna on the top of the front window. Installation position of on-glass antennas are changeable defends on driver, so we proposed Interdigital capacitor in feeding point to achieve matching characteristic with no position limit. The measurement result showed good return loss characteristic-below -6 dB in the T-DMB frequency band and maintained fixed resonant frequency.

A Design of 77 GHz LNA Using 65 nm CMOS Process (65 nm CMOS 공정을 이용한 77 GHz LNA 설계)

  • Kim, Jun-Young;Kim, Seong-Kyun;Cui, Chenglin;Kim, Byung-Sung
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.9
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    • pp.915-921
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    • 2013
  • This work presents a 77 GHz low noise amplifier(LNA) for automotive radar systems using 65 nm RF CMOS process. The LNA is composed of three stage common source amplifiers and includes transmission line matching networks. To reduce the time for three dimensional EM simulation, we optimize the transmission line impedance matching network using a pre-built EM library. The proposed compact simulation technique is confirmed by measurement results. The peak gain of the LNA is 10 dB at 77 GHz and input/output return losses are below -10 dB around the design frequency.

Research on Standards for Protection against Electric Shock in Global Technical Regulations of Fuel Cell Vehicle (연료전지 자동차 세계기술규정의 감전보호기준 연구)

  • HwangBo, Cheon;Lee, Kyu-Myong;You, Kyeong-Jun
    • Journal of Hydrogen and New Energy
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    • v.21 no.3
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    • pp.167-183
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    • 2010
  • This paper analyzes the backgrounds of the standards for protection against electric shock in Global Technical Regulations (GTR) of Fuel Cell Vehicle (FCV). Targets on research were high voltage criteria, safety current, isolation and grounding resistance, time limitation, energy, adequate clearance, and test procedure. Based on human impedance and effect of current in IEC 60479-1, safety of human was examined. Then, isolation and grounding circuit model of FCV were analyzed theoretically. The results give several suggestions: touch voltage less than 25V, AC energy less than 0.0813J, separation considering middle finger length, grounding resistance less than $0.2\Omega$, maximum AC ground voltage of 1V (rms), and isolation resistance between earth and electrical chassis. In MATLAB/Simulink environment, error characteristics of isolation resistance measurement procedure using internal DC sources were analyzed under variations of internal resistance of voltmeter and isolation resistance.

Ginger Extract as Green Corrosion Inhibitor for Steel in Sulfide Polluted Salt Water

  • Fouda, Abd El-Aziz S.;Nazeer, Ahmed Abdel;Ibrahim, Mohamed;Fakih, Mohamed
    • Journal of the Korean Chemical Society
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    • v.57 no.2
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    • pp.272-278
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    • 2013
  • Extract of ginger has been evaluated as a green inhibitor for the corrosion of steel in sulfide polluted NaCl solution using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. Potentiodynamic polarization measurements showed that this extract acts as a mixed type inhibitor but mainly inhibits the cathodic reaction. The inhibition efficiency was found to increase with inhibitor concentration reaching to approximately 83.9% using 250 ppm of ginger. Nyquist plots show a single capacitive loop in uninhibited and inhibited solutions. From EFM the causality factors are very close to theoretical values which indicate that the measured data are of good quality. The adsorption process of the studied extract on steel surface obeys Temkin adsorption isotherm. The results obtained from the different electrochemical techniques were in good agreement which prove the validity of these tools in measurement of corrosion rate. Ginger extract has no effect on Escherichia Coli and can be applied safely on waste water treatment plants.

Optimization Analysis for Homogeneous Field Structure of GTEM-CELL (GTEM-CELL의 균일한 필드구조를 갖기위한 최적화 분석)

  • Kim, Jong-Seong;Seo, Kang;Jeong, Seong-IL;Lee, Han-Young;Lee, Jong-Arc
    • Journal of IKEEE
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    • v.7 no.2 s.13
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    • pp.218-222
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    • 2003
  • Even if using the standard field test which radiation of electric wave and measurement test equipment there are difficult thing that building test equipment. so, we can use the substitution test field. In this paper, for optimization analysis for homogeneous field structure of GTEM-CELL (Giga hertz Transverse Electro Magnetic Cell) that calculate electromagnetic field characteristic for variable of each structure and characteristic impedance inner conductor.

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A 4-port MIMO Antenna for LTE Femtocell using Cross Decoupler (Cross Decoupler를 이용한 LTE 펨토셀용 4-port MIMO 안테나)

  • Ahn, Sang-Kwon;Jeong, Gye-Taek;Lee, Hwa-Choon;Kwak, Kyung-Sup
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.13 no.2
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    • pp.50-56
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    • 2014
  • This paper describes the design, fabrication, and measurement of a 4-port femtocell MIMO antenna for LTE 700MHz(Band12, 13, 14, 17, 28, 44) applications. Based on microstrip patch antenna, an impedance matching is achieved by short pin. In order to obtain sufficient bandwidth and isolation between antenna elements in a limited dimension, a cross decoupler is used. With a Voltage Standing Wave Ratio (VSWR)${\leq}2$, the measured result of the fabricated antenna provides 105MHz(0.698~0.803MHZ) bandwidth and shows the gain with 1.97dBi and isolation above 13dB. As one of the key parameters for MIMO performance evaluation, correlation coefficient of MIMO is achieved within 0.2.

Effect of octadecylamine concentration on adsorption on carbon steel surface

  • Liu, Canshuai;Lin, Genxian;Sun, Yun;Lu, Jundong;Fang, Jun;Yu, Chun;Chi, Lisheng;Sun, Ke
    • Nuclear Engineering and Technology
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    • v.52 no.10
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    • pp.2394-2401
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    • 2020
  • Octadecylamine is an effective film-forming amine that protects carbon steel from corrosion. In the present study, the effect of octadecylamine concentration on adsorption on a carbon steel surface was investigated in anaerobic alkaline solution by using SEM/EDS, TEM and the Materials Studio simulation techniques. TEM morphology observation and EDS elemental detection determine the thicknesses of octadecylamine film on a carbon steel surface, which are confirmed by the in-situ electrochemical impedance spectroscopy measurement and resistance calculation. The Materials Studio simulation reveals the number of octadecylamine film layers at different concentrations. Results obtained in this study indicate that adsorption of octadecylamine film on carbon steel proceeds with the multi-layer adsorption mechanism.

5.8 GHz Microwave Wireless Power Transmission System Development and Transmission-Efficiency Measurement (5.8 GHz 마이크로파 무선전력전송 시스템 개발 및 전송효율측정)

  • Lee, Seong Hun;Son, Myung Sik
    • Journal of the Semiconductor & Display Technology
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    • v.13 no.4
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    • pp.59-63
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    • 2014
  • Previous studies have selected wireless power transmission system using 2.45 GHz of ISM band, but the researches for 5.8 GHz microwave wireless power transmission have been relatively rare. The 5.8 GHz has some advantages compared with 2.45 GHz. Those are smaller antenna and smaller integrated system for RFIC. In this paper, the 5.8 GHz wireless power transmission system was developed and transmission efficiency was measured according to the distance. A transmitter sent the amplified microwaves through an antenna amplified by a power amplifier of 1W for 5.8 GHz, and a receiver was converted to DC from RF through a RF-DC Converter. In the 1W 5.8GHz wireless power transmission system, the converted currents and voltages were measured to evaluate transmission efficiency at each distance where LED lights up to 1m. The RF-DC Converter is designed and fabricated by impedance matching using full-wave rectifier circuit. The transmission-efficiency of the system shows from 1.05% at 0cm to 0.095% at 100cm by distance.

Injury and inflammation detection by the application of microcurrent through the skin

  • Hui, Timothy;Petrofsky, Jerrold
    • Physical Therapy Rehabilitation Science
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    • v.2 no.1
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    • pp.31-38
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    • 2013
  • Objective: To determine the efficacy and reliability of measuring direct current microcurrent applied through the skin to determine injury in the underlying tissues. Design: Case control study. Methods: First, microcurrent was measured as decreased blood flow induced hypoxia in healthy subjects. Next, reliability was assessed by measuring over ten days with set variations in pressure and distance between the electrodes. Finally, measurements over sprained ankle were compared to measurements over comparable uninjured areas on the same injured subject. Results: For the blood flow test phase, microcurrent significantly decreased an average of 17% after 5 minutes (p<0.05), remained decreased for 30 seconds, and returned to non-occlusive levels after 2 minutes of normal circulation. The results indicate that the microcurrent decrease was not due to blood flow, and most likely from hypoxic cellular damage. For the reliability phase, the coefficients of variation averaged 10.3% for the shoulder, 14.8% for the low back, and 29.1% for the knee. Changing distance 2.5 cm between the electrodes resulted in insignificant changes. Changes in pressure had some significant effect after an increase in force of 2.6 N, affirming the need for consistent pressure for measurement. For the injury test phase, a significant 69% decrease occurred comparing injured areas to the same area on the uninjured side, and a significant 74% occurred comparing injured and non-injured areas on the same limb. Conclusions: Microcurrent through the skin shows promise as an objective method of assessing a soft tissue injury by detecting damage likely due to hypoxia.

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Analysis of Via Fence Effects in PCB Transmission Lines (PCB 전송선에서 비아 펜스의 효과 분석)

  • Kim Jong-Ho;Park Sang-Wook;Ju Jae-Cheol;Park Dong-Chul
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.4 s.95
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    • pp.402-409
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    • 2005
  • In analog and digital electronic systems, crosstalk between transmission lines on the printed circuit board can degrade the performance of equipment operations. This paper presents a technique to analyze the effects of via fence, which is based on additional transmission lines grounded by vias. The technique is composed of a circuit concept approach for transmission line sections md an impedance modeling of via hole sections. All sections are represented by ABCD parameters and they are cascaded. Finally, this technique was verified by comparing the measurement results with the simulation ones.