• Title/Summary/Keyword: Impedance Measurement

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Parammeter Optimization of the Electromagnetically Coupled Broadband Microstrip Antenna by Finite Difference Time Domain Method (시간영역 유한차분법을 이용한 전자기 결합 광대역 마이크로스트립 안테나의 파라메타 최적화)

  • 김정렬;윤현보
    • The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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    • v.6 no.1
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    • pp.17-27
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    • 1995
  • In this paper, Finite Difference Time Domain (FDTD) method is used to analyze characteristics of the electromagnetically coupled broadband microstrip antenna, and to optimize the antenna parameters. By using short tuning stub in feedline, electromagnetically coupled microstrip antenna shows broadband (approximatcly equal 13%) characteristics, and the characteristics are varied as a function of length, width, and position of the tuning stub. Operating frequency, return loss, VSWR and input impedance are calculated by Fourier transforming the time domain results. Measurement data from fabricated electromagnetically coupled microstrip antenna are compared with FDTD results and are shown to be in good agreement. After optimization of the parameters, maximum bandwidth of about 15% is achieved.

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A novel free-standing anode of CuO nanorods in carbon nanotube webs for flexible lithium ion batteries

  • Lee, Sehyun;Song, Hyeonjun;Hwang, Jun Yeon;Kim, Seung Min;Jeong, Youngjin
    • Carbon letters
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    • v.27
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    • pp.98-107
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    • 2018
  • Free-standing electrodes of CuO nanorods in carbon nanotubes (CNTs) are developed by synthesizing porous CuO nanorods throughout CNT webs. The electrochemical performance of the free-standing electrodes is evaluated for their use in flexible lithium ion batteries (LIBs). The electrodes comprising CuO@CNT nanocomposites (NCs) were characterized by charge-discharge testing, cyclic voltammetry, and impedance measurement. These structures are capable of accommodating a high number of lithium ions as well as increasing stability; thus, an increase of capacity in long-term cycling and a good rate capability is achieved. We demonstrate a simple process of fabricating free-standing electrodes of CuO@CNT NCs that can be utilized in flexible LIBs with high performance in terms of capacity and cycling stability.

Narrow Resonant Double-Ridged Rectangular Waveguide Probe for Near-Field Scanning Microwave Microscopy

  • Kim, Byung-Mun;Son, Hyeok-Woo;Cho, Young-Ki
    • Journal of Electrical Engineering and Technology
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    • v.13 no.1
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    • pp.406-412
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    • 2018
  • In this paper, we propose a narrow resonant waveguide probe that can improve the measurement sensitivity in near-field scanning microwave microscopy. The probe consists of a metal waveguide incorporating the following two sections: a straight section at the tip of the probe whose cross-section is a double-ridged rectangle, and whose height is much smaller than the waveguide width; and a standard waveguide section. The advantage of the narrow waveguide is the same as that of the quarter-wave transformer section i.e., it achieves impedance-matching between the sample under test (SUT) and the standard waveguide. The design procedure used for the probe is presented in detail and the performance of the designed resonant probe is evaluated theoretically by using an equivalent circuit. The calculated results are compared with those obtained using the finite element method (Ansoft HFSS), and consistency between the results is demonstrated. Furthermore, the performance of the fabricated resonant probe is evaluated experimentally. At X-band frequencies, we have measured the one-dimensional scanning reflection coefficient of the SUT using the probe. The sensitivity of the proposed resonant probe is improved by more than two times as compared to a conventional waveguide cavity type probe.

A study on Electrical and Electromagnetic Properties for Driving the Ring-shaped electrodeless fluorescent lamp (환형 무전극 형광램프 구동을 위한 전기적, 자기적 특성 분석)

  • Jo, Ju-Ung;Lee, Young-Hwan;Nam, Joong-Hee;Choi, Yong-Sung;Kim, Yong-Kab;Park, Dae-Hee
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.05b
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    • pp.69-72
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    • 2004
  • In recent, there have been several developments in lamp technology that promise savings in electrical power consumption and improved quality of the lighting space. Above all, the advantage of ring-shaped electrodeless fluorescent lamp is the removal of internal electrodes and heating filaments that are a light-limiting factor of conventional fluorescent lamps. The ring-shaped electrodeless lamp is intended as a high efficacy replacement for the incandescent reflector lamp in many applications. Therefore, the life time of ring-shaped electrodeless fluorescent lamps is substantially higher than that of conventional fluorescent lamps and last up to 60,000 hours. In this paper, we present measurement results of electrical characteristics of a ring-shaped electrodeless fluorescent lamp as a function of frequency and number of coil turns using a highly permeable Mn-Zn ferrite. It is found that the impedance are increased while the quality factor decreases as frequency increases.

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Study on Impedance Measurement and Matching for Medium-Voltage Powerline Communications (고압 전력선 통신을 위한 임피던스 측정과 정합 방안 연구)

  • Yu, Jung-Hun;Choi, Seung-Ji;Park, Young-Jin;Lee, Won-Tae;Kim, Kwan-Ho;Hong, Choong-Seon;Lee, Dae-Young
    • Proceedings of the KIEE Conference
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    • 2003.07c
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    • pp.1981-1983
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    • 2003
  • 본 연구에서는 고속전력선통신(PLC)을 위한 고압배전선의 임피던스 측정 방법을 소개한다. 현재 전세계적으로 고속 PLC를 위해서 1MHz${\sim}$30MHz대역을 사용하고 있다. 임피던스 특성을 실제 필드에서 측정하기 위해 본 연구에서는 휴대용 고압결합장치를 개발하였다. 임의의 고압 배전선에 일시적으로 결합할 수 있도록 고안된 고압결합장치로서 살아있는 전력선에 정전 없이 설치 가능하다. 이 장치는 고압용 커풀러(Coupler)와 60Hz 저주파를 차단하기 위한 드레인 코일(drain coil)로 구성되었다. 측정을 위해서는 벡터 회로망 분석기를 사용하였으며, 본 논문에서는 측정된 고압선 임피던스를 보여 주고 이 결과를 이용한 임피던스 정합 방법을 제시하였다.

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Characteristics of Radiated Electromagnetic Waves in Model GIS with Electrical Trouble and Design of Insulted Diagnosis UHF Sensor (모의 GIS의 전기적 이상에 따른 방사전자파의 특성과 절연진단용 UHF 센서 설계)

  • Park, Kwang-Seo
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.5
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    • pp.47-52
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    • 2008
  • In this paper partial discharge were simulated by conducted particle, a fine protrusion, surface discharge, which could be easy accumulated charge and concentrated electric field in the model GIS. In this times this paper measured and analyzed the radiated electromagnetic waves by using spectrum analyzer and antenna ($30{\sim}2,000[MHz]$ for measurement of EMI EMC in accordance with occurrence and propagation of partial discharge. In the basis of this results, a novel UHF(Ultra High Frequency) spherical sensor is presented. The measured impedance bandwidth of the proposed antenna is from 0.3[GHz] to 1.7[GHz]. Form results of this study, this antenna will be playing an important role for the sensor for insulation diagnosis system by UHF method of real site GIS and power equipment using $SF_6$ gas.

Sound Absorption Property of the Leaves of Two Evergreen Broad-Leaved Tree Species, Dendropanax morbiferus and Fatsia japonica

  • JUNG, Su Young;YEOM, Da-Hye;KONG, Ree-Keun;SHIN, Gab Gyun;LEE, Kwang Soo;BYEON, Hee Seop
    • Journal of the Korean Wood Science and Technology
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    • v.48 no.5
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    • pp.631-640
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    • 2020
  • In this study, the effect of specimen size and layer thickness on the sound absorption of the leaves of two evergreen broad-leaved tree species, Dendropanax morbiferus and Fatsia japonica, was investigated. The specimen sizes of 0.5 × 0.5, 1.0 × 1.0, and 2.0 × 2.0 ㎠ and layer thicknesses of 1.00, 1.75, and 2.50 cm were considered. At the layer thickness of 2.5 cm, the leaf of the D. morbiferus showed no significant difference in sound absorption coefficients (SACs) as the sample size varied, however, a significant change in SACs was recorded in that of the F. japonica. At 1.0-cm thickness, the SACs of the F. japonica leaf varied more remarkably with the sample size. The 2.50-cm-thick F. japonica leaf with the specimen size 0.5 × 0.5 ㎠ exhibited the highest sound absorption effect among all samples investigated.

Design of piezoelectric Shunt Structure using Admittance Analysis with Application to O.D.D. Main Base (어드미턴스를 이용한 압전 션트 구조물의 설계방법과 O.D.D. 메인 베이스로의 응용)

  • Park, Jong-Sung;Lim, Soo-Cheol;Choi, Seung-Bok;Kim, Jae-Hwan;Park, Young-Pil
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.403-406
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    • 2004
  • In this paper, the design of damped structures associated with the piezoelectric shunt circuits is undertaken and it is applied to optical disk drive (O.D.D) main base in order to reduce unwanted vibration. In order to design effective piezoelectric structure, the admittance of the structure is introduced as the performance index of the piezoelectric shunt system. And the admittance offset of the shunt performance is theoretically investigated. It is also presented that the admittance can be calculated by commercial finite elements program. To verify the admittance calculated by F.E.M, admittance measurement is performed by impedance analyzer. In this verifying process, the validity of the finite element admittance analysis is found. As a practical approach, to reduce the vibration of the O.D.D. main base, piezoelectric shunt system is designed using the proposed admittance analysis and shunt effect is evaluated at all prescribed frequencies.

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Measurement and Investigation of Apparent Masses of a Human Body at the Sitting Posture in a Passenger Car (승용차 착석 자세에서의 인체 겉보기 질량 측정 및 고찰)

  • Jang, Han-Kee;Hong, Seok-In;Kim, Ki-Sun;Lee, Jeong-Hoon;Kim, Kwang-Joon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.369-374
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    • 2004
  • This study aims to measure an apparent mass of a seated human body at the sitting posture in a passenger car in the frequency range from 1 to 20 Hz and to investigate the dynamic characteristics. Thirty subjects joined the test where eight levels of acceleration from $0.1m/s^2\;to\;2.0m/s^2$ were used to excite seated human body. Most of apparent mass curves showed two peaks in the frequency range of $4\sim9Hz$, first peak was clearer at the contact point of the seat and the hip, and the second one at the contact point of the backrest and the back. Both peak frequencies were found to move down to lower frequencies with increase of acceleration magnitude. Shapes of apparent mass curves were clearly different from those at erect posture especially in the frequency range around and above the second peak.

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On the selection of loads in the multi-load method for measuring in-duct source characteristics (덕트 내 음원 특성 측정을 위한 다중부하법의 부하 선택에 관한 연구)

  • Jang, Seung-Ho;Ih, Jeong-Guon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.11a
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    • pp.384-388
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    • 2000
  • One-port acoustic characteristics of an in-duct source can be measured by the multi-load method using an overdetermined set of open pipes with different lengths as applied loads. The input data. viz. load pressure and load impedance, are usually contaminated by measurement error in the actual measurements, which result in errors in the calculated source parameters. In this paper, the effects of the errors in the input data on the results have been studied numerically, varying the number of loads and their impedances in order to determine what combination of the loads will yield the best result. An error analysis is applied to each case of possible loads, which consist of open pipes. It is noted that, frequently, only a set of open pipes is used when applying the multi-load method to the intake or exhaust sides of internal combustion engines. A set of pipe lengths which cause the calculated results to be least sensitive to the input data error can be found when using open pipe loads. The present work is intended to produce guidelines for preparing an appropriate load set in order to obtain accurate source properties of fluid machines.

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