• Title/Summary/Keyword: Transfer standard

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A W-Band Millimeter-Wave Power Standard Transfer System Using the Direct Comparison Method (직접 비교법을 이용한 W-Band 밀리미터파 전력 표준 전달 시스템)

  • Kwon, Jae-Yong;Kang, Tae-Weon;Kang, Jin-Seob;Lee, Dong-Joon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.24 no.1
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    • pp.47-54
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    • 2013
  • This paper introduces a W-band millimeter-wave power standard transfer system using the direct comparison method. The transfer system was developed to evaluate the effective efficiency and calibration factor of a W-band waveguide power sensor. The evaluation method and the measured results of the directional coupler that characterizes the calibration system are studied. The uncertainties of the standard transfer system are investigated, and the major uncertainty contributors are discussed as well. The performance of the realized W-band power standard transfer system was verified by comparing results with reference values.

Development of an Input Impedance Evaluation of the AC-DC Transfer Standard for Low Level AC Voltage Standard (교류 저전압 표준용 교류-직류 변환기의 입력임피던스 평가기술 개발)

  • Kwon, Sung-Won;Jung, Jae-Kap;Lee, Sang-Hwa;Kim, Myung-Soo;Kim, Han-Jun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.2
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    • pp.229-234
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    • 2008
  • An AC-DC transfer standard(TS) is used for the AC voltage standard in the range of 2 mV to 1000 V below 1 MHz. Micro-potentiometer(${\mu}Pot$) is used to evaluate the ac-dc transfer difference(ADD) of the TS below 200 mV range. The ADD of the TS were changed by the loading effect caused from the input impedance change of the TS depend on frequency. An input impedance evaluation technique of the TS using ${\mu}Pot$ has been developed.

Effect of Si on Arc Stability of MAG Welding (MAG용접의 Arc안정성에 미치는 Si의 영향)

  • 안영호;이종봉;엄동석
    • Journal of Welding and Joining
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    • v.16 no.6
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    • pp.52-58
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    • 1998
  • The effect of Si content in welding wires on th arc stability was investigate, in the region of short circuit transfer and spray transfer. In the region of short circuit transfer, with increasing Si content, average arcing time and average short circuit time were increased. Therefore, droplet transfer frequency was decreased, due to the increase of arcing time and peak current at the moment of arc-reiginition was increased, due to the increase of short circuit time. In the region of spray transfer, the fluctuations of arc current and arc voltage was the most stable in wire with Si content of about 00.60 wt.%.

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Effect of S on Spatter Generation and Droplet Transfer Phenomena of MAG Welding (MAG용접의 스패터 발생 및 용적이행현상에 미치는 S의 영향)

  • 안영호;이종봉;최원규
    • Journal of Welding and Joining
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    • v.19 no.5
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    • pp.486-491
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    • 2001
  • The effect of S content in welding wires on spattering characteristics and droplet transfer phenomena was studied. In MAG welding using 80%Ar-$20%CO_2$ shielding gas, spattering characteristics and droplet transfer phenomena were varied with S content of wire. Sulfur addition in wire reduced surface tension of droplet and weld pool, and made arc more stable in MAG welding. With increasing S content, the spattering ratio and the ratio of large size spatter ($d{\geq}1.0mm$) were reduced in short circuit transfer mode. In spray transfer mode, spattering ratio, however was increased when sulfur was added more than 0.020wt.% because surface tension of droplets and weld pool was reduced too much even though arc stability was improved.

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GEO-KOMPSAT-2 LAE Burn Plan in Supersynchronous Transfer Orbit (정지궤도복합위성의 SSTO 액체원지점엔진 점화계획)

  • Park, Bong-Kyu;Choi, Jae-Dong
    • Aerospace Engineering and Technology
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    • v.13 no.2
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    • pp.122-130
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    • 2014
  • GEO-KOMPSAT-2 which is under development by KARI to be launched in 2018 is expected to be injected into its orbit through the standard GTO(Geostationary Transfer Orbit) or SSTO(Supersynchronous Transfer Orbit). While the standard GTO mission has been applied for the most of the geostationary satellites, the SSTO mission is rare case and significantly different from the standard GTO mission in technical point of view. This paper lists the operational constraints to be applied for GEO-KOMPSAT-2 SSTO mission, and introduces a preliminary LAE burn plan for GEO-KOMPSAT-2 mission. In order to evaluate the developed plan, a simulation study has been performed considering ground station visibility.

Surface Transfer Impedance Measurement of RF Cable according to IEC Standard 96-1 (IEC Standard 96-1에 따른 RF 케이블의 표면전달 임피던스 측정)

  • 강진섭;김정환;강웅택;박정일
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.11 no.6
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    • pp.886-892
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    • 2000
  • In this paper, surface transfer impedance measurement of RF cables according to IEC(International Electrotechnical Commission) Standard 96-1 is described and surface transfer impedance of a commercial RF cable is obtained from the measured voltage and scattering parameter with a triaxial fixture fabricated in the operating frequency range from 1 MHz to 30 MHz.

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Study on the Standard Oxygen Transfer Efficiency Monitoring System in the Aeration Tank for Reuse and Discharge of Wastewater (하폐수의 재사용 및 방류를 위한 폭기조 내 표준산소전달 효율 모니터링 시스템에 관한 연구)

  • Kim, Hong-Seok;Kim, Yong-Beom;Ko, Kyung-Han;Kim, Sang-Woo;Shim, Hwan-bo
    • Resources Recycling
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    • v.28 no.6
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    • pp.73-78
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    • 2019
  • In this investigation, off-gas generated from the activated sludge in wastewater treatment plant was monitored. Through monitoring, the oxygen transfer efficiency in the aeration system and the reliability was evaluated by comparing to clean water. First, the dissolved oxygen, oxygen transfer coefficient, and standard oxygen transfer efficiency were measured based on clean water, and the values were 8.60 mg/L, 9.490/hr and 23.96%, respectively. The off-gas monitoring at the wastewater treatment plant indicated that the standard oxygen transfer efficiency was 22.81%. Little difference in oxygen transfer efficiency this data inferred that the performance was improved through diffuser installation in the field monitoring system.

Prediction of Forced Convective Boiling Heat Transfer Coefficient of Pure Refrigerants and Binary Refrigerant Mixtures Inside a Horizontal Tube

  • Kim, Min-Soo;Hong, Eul-Cheong;Shin, Jee-Young;Kyungdoug Min;Ro, Sung-Tack
    • Journal of Mechanical Science and Technology
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    • v.17 no.6
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    • pp.935-944
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    • 2003
  • Forced convective boiling heat transfer coefficients were predicted for an annular flow inside a horizontal tube for pure refrigerants and nonazeotropic binary refrigerant mixtures. The heat transfer coefficients were calculated based on the turbulent temperature profile in liquid film and vapor core considering the composition difference in vapor and liquid phases, and the nonlinearity in mixing rules for the calculation of mixture properties. The heat transfer coefficients of pure refrigerants were estimated within a standard deviation of 14% compared with available experimental data. For nonazeotropic binary refrigerant mixtures, prediction of the heat transfer coefficients was made with a standard deviation of 18%. The heat transfer coefficients of refrigerant mixtures were lower than linearly interpolated values calculated from the heat transfer coefficients of pure refrigerants. This degradation was represented by several factors such as the difference between the liquid and the overall compositions, the conductivity ratio and the viscosity ratio of both components in refrigerant mixtures. The temperature change due to the concentration gradient was a major factor for the heat transfer degradation and the mass flux itself at the interface had a minor effect.

Efficiency and EMF Safety Analysis of Wireless Power Transfer System Using Standard Human Model (표준화된 인체모델을 이용한 공진형 무선전력전송 시스템의 효율 변화 및 인체 안전성 분석)

  • Shin, Hansu;Byun, Jin-Kyu
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.27 no.11
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    • pp.96-103
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    • 2013
  • In this paper, resonant wireless power transfer systems are designed with double loop resonant coils for the resonant frequency of 150kHz. The transfer efficiency characteristics is analyzed according to the coil size, and the distance and misalignment between the coils. Then the change in efficiency is investigated when a human model is located between the resonant coils using the homogeneous human phantom of IEC-62311 standard. Also, in order to assess the safety of the wireless power transfer system, the induced current density inside the human model is calculated when it is exposed to the magnetic field of a plane wave and resonant coil. Then, the results are compared with the exposure limits in the EMF (electromagnetic field) safety guidelines.

Effect of Si on Spatter Generation and Droplet Transfer Phenomena of MAG Wwlding (MAG 용접의 스패터 발생 및 용적이행현상에 미치는 Si의 영향)

  • 안영호;이종봉;엄동석
    • Journal of Welding and Joining
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    • v.17 no.3
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    • pp.36-43
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    • 1999
  • The effect of Si content in welding wires on spattering characteristics and droplet transfer phenomena was studied. In MAG welding using 80% Ar-20% $CO_2$ shielding gas, spattering characteristics and droplet transfer phenomena were varied with Si content of wire. With increasing Si content, the spattering ratio and the ratio of large size spatter $(d\geq1.0mm)$ were increased. The increase of Si content in molten metal made surface tension increase due to reduction of oxygen content, which resulted from deoxidizing action of silicon. The increase of surface tension resulted in unstable transfer phenomena and arc instability in both short circuit and spray region. With changing Si content of wire, spattering characteristics and droplet transfer phenomena was directly influenced by the variation of surface tension, compared with the effect of arc stability.

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