• Title, Summary, Keyword: Standard Attenuator

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Flatness Characteristics Analysis Technique of Attenuator Using Thermal Voltage Converter and AC Measurement Standard (열전압변환기와 교류측정표준을 사용한 감쇠기 평탄도 특성 분석 기법)

  • Cha, Yun-bae;Kim, Boo-il
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.22 no.2
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    • pp.330-337
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    • 2018
  • This paper proposes a technique to analyze the flatness characteristics of the attenuator at 10Hz to $50\text\tiny{MHz}$ on the basis of $1\text\tiny{kHz}$ using a Thermal Voltage Converter and AC measurement standard. In the proposed technique, the input voltage of the attenuator for each measuring frequency is supplied at the same rate as $1\text\tiny{kHz}$ using TVC, and the flatness characteristics of the attenuator are analyzed by the voltage variation indicated in the AC measurement standard. The results of the analysis of the attenuator flatness characteristics show that the maximum uncertainty of $866{\mu}V/V$ can be measured from $10\text\tiny{dB}$ to $70\text\tiny{dB}$ and the uncertainty is reduced by about 37% compared to $2.31\text\tiny{mV}$/V using the network measurement method. The improved attenuator flatness characteristic values can be applied to the frequency flatness calibration from 2.2V to 2.2mV at the low voltage of the AC measurement standard.

A Study on the Development and of Establishment Performance Evaluation Criteria of Working Truck Mounted Attenuator (작업차량 장착용 충격흡수장치(TMA) 성능평가기준 수립 및 개발 연구)

  • Joo, Jae-Woong;Jang, Dae-Young;Park, Je-Jin
    • Journal of the Korean Society of Safety
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    • v.27 no.6
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    • pp.185-191
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    • 2012
  • Rear collisions to expressway work trucks result many casualties these days. But, currently, no special measure are being taken except deploying sign trucks behind the working trucks. In the U.S and Europe, trucks with TMA(Truck Mounted Attenuator) are being deployed behind the working truck, which is regarded as the standard method for work area safety, thereby reducing the fatality rates and property damage tremendously. Also, standard for the performance of TMA are established and TMA can be used in the field only when it satisfies the standard. In Korea, neither the standard for nor any guide to the TMA exists. In the situation some manufacturer developed TMA without proper performance evaluation and marketed limited number of TMAs in the field. In the study, NCHRP350, which is the performance standard of expressway safety features of U.S. and materials related to the TMA standard in Europe have been reviewed to establish the Korean performance criteria. Based on the review, and incorporating existing Korean standard for crash cushions, domestic standard for TMA has been proposed and applied in developing Korean TMA and crash tested it to verify the performance. The original design developed was crash tested and modified. The newly proposed design was studied using impact simulation program several times. Modifications were made after each simulation and prototype was built and crash tested as per the newly established TMA performance criteria.

Out-of-Band Measurement of LED-based Solar Blind UV Filters

  • Cui, Muhan;Zhou, Yue;Chen, Xue;Yan, Feng;Zhang, Mingchao;Yang, Huaijiang
    • Journal of the Optical Society of Korea
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    • v.18 no.3
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    • pp.244-250
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    • 2014
  • Due to the difficulty in measuring very low out-of-band cutoff depths of solar blind UV filters, we propose a cutoff depth adjustable measurement system (CDAM) to test deep cutoff filters with a large dynamic range. The CDAM utilizing the substitution method is elaborately composed of several parts, including narrow-band LED light sources, standard reflective neutral attenuators with known attenuation coefficients, and a photomultiplier (PMT). This paper also presents an attenuator combination method ensuring that the PMT works within its linear response range. In addition, numerical simulation testifies to the method, and experiment shows that the CDAM system can achieve an extension of dynamic range from 0-6 OD to 0-10 OD, which is sufficient for the measurement of out-of-band cutoff depths of solar blind UV filters. Above all, the CDAM system, being easily implemented, of wide dynamic range, and highly precise, could be widely used in the measurement of filter cutoff depth.

Design and Fabrication of K-band Attenuation Standard (K-대역 감소량 표준기의 설계 및 제작)

  • Lee Joo-Gwang;Kim Jeong-Hwan;Kang Jin-Seob;Kang Tae-Weon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.4
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    • pp.387-392
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    • 2006
  • In this paper, measurement scheme and uncertainty estimation of the K-band attenuation standard fitted with 3.5 mm coaxial connectors are described. The standard comprises a build-up chain of four steps of power ratio mea-surement and operates in the frequency range of 18 GHz to 26.5 GHz. The nominal attenuation of each step is around 20 dB and total dynamic range is 80 dB. The expanded uncertainty of the overall system is 0.01 dB at the confidence level of approximately 95%.

Optical coherence tomography topology design for SNR improvment (SNR 향상을 위한 OCT topology의 설계)

  • Park, Yang-Ha;Jung, Tae-Ho;Oh, Sang-Gi;Kim, Yoo-Hee
    • Proceedings of the KIEE Conference
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    • pp.212-214
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    • 2002
  • Basically, OCT use the interference effect of Michelson interferometer. The receiver noise of interferometer is a important fact to improve the system performance. To improve the system performance for high resolution image processing, we design a interferometer topology adding the attenuator to the reference arm. In this paper, we design the receiver noise parameter and computer simulation. In this results, SNR of the new topology system is improved 5dB compare to standard interferometer.

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Uncertainty in the Course of Calibration of RF Multimeter using TVC (열전압변환기를 이용한 고주파전압계의 교정과 측정불확도)

  • 박정규;박석주;이환상;장경승;박명선
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.13 no.1
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    • pp.47-52
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    • 2002
  • It was virtually declared that measurement science must abandon the error analysis of measurement when ISO had published "Guide to Expression of uncertainty in Measurement" International inclination of measurement field in order to guarantee the traceability and confidence of measurement results discards the error concept and instead analyzes the measurement uncertainty. In this paper we establish a mathematical model of measurement and analyze all uncertainty factors as possible as for yielding the measurement uncertainty in the course of the calibration of RF multimeter using Transfer Standard, Thermal Voltage Converter We produce the expanded uncertainty by analyzing cable effects, correlation of thermocoupler and DC meter, DC source, RF source, attenuator, reflection coefficients and DUT.s and DUT.

A VHF/UHF-Band Variable Gain Low Noise Amplifier for Mobile TV Tuners (모바일 TV 튜너용 VHF대역 및 UHF 대역 가변 이득 저잡음 증폭기)

  • Nam, Ilku;Lee, Ockgoo;Kwon, Kuduck
    • Journal of the Institute of Electronics and Information Engineers
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    • v.51 no.12
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    • pp.90-95
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    • 2014
  • This paper presents a VHF/UHF-band variable gain low noise amplifier for multi-standard mobile TV tuners. A proposed VHF-band variable gain amplifier is composed of a resistive shunt-feedback low noise amplifier to remove external matching components, a single-to-differential amplifier with input PMOS transcoductors to improve low frequency noise performance, a variable shunt-feedback resistor and an attenuator to control variable gain range. A proposed UHF-band variable gain amplifier consists of a narrowband low noise amplifier with capacitive tuning to improve noise performance and interference rejection performance, a single-to-differential with gm gain control and an attenuator to adjust gain control range. The proposed VHF-band and UHF-band variable gain amplifier were designed in a $0.18{\mu}m$ RF CMOS technology and draws 22 mA and 17 mA from a 1.8 V supply voltage, respectively. The designed VHF-band and UHF-band variable gain amplifier show a voltage gain of 27 dB and 27 dB, a noise figure of 1.6-1.7 dB and 1.3-1.7 dB, OIP3 of 13.5 dBm and 16 dBm, respectively.

Fabrication of Multiple-Frequency Exposure System for In Vitro Experiment (세포 실험용 다중 주파수 동시 노출 장치 제작)

  • Kim, Tae-Hong;Seo, Min-Gyeong;Mun, Ji-Yeon;Pack, Jeong-Ki
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.23 no.2
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    • pp.213-219
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    • 2012
  • Recently, we are simultaneously exposed by various electromagnetic sources due to an increase of mobile communication services. However, EMF(Electric, Magnetic and Electromagnetic Field) study has been performed mainly about only single frequency. The objective of this paper is to develop an multiple-frequency exposure system for in vitro experiment. The exposure unit for in vitro experiments was designed by radial transmission line type to get broadband characteristics to generate signals of CDMA at 836.5 MHz and WCDMA at 1950 MHz frequency simultaneously. The modulated signals were delivered to the conical antenna through amplifier, digital attenuator and RF combiner. SAR values were obtained by the averaged values of 3 measured values at 9 points in petri dish using the fiber optic temperature probe. The measured return loss was under -15 dB. For 1 W input power, the mean value and standard deviation of SAR were $0.105{\pm}0.019$ for the CDMA frequency and $0.262{\pm}0.055$ for the WCDMA frequency.