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KOLAS 교정기관의 측정동등성 확립을 위한 물유량 숙련도 시험
전세종,윤병로,김수진,Chun, Sejong,Yoon, Byung-Ro,Kim, Soo-Jin 대한기계학회 2017 대한기계학회 논문집. Transactions of the KSME. C, 산업기술과 혁신 Vol.5 No.2
KOLAS (KOrea Laboratory Accreditation Scheme) belongs to APLAC (Asia Pacific Laboratory Accreditation Cooperation). KOLAS manages the accreditation scheme for measurement traceability to SI units. As per June 2016, there are 22 KOLAS laboratories for liquid flow metering. Among them, 12 laboratories participated in the proficiency test (PM2015-08) for water flow metering, organized by KASTO (Korea Association of Standards and Testing Organizations). This proficiency test was performed with three kinds of flow ranges ($3.6m^3/h{\sim}12m^3/h$, $40m^3/h{\sim}80m^3/h$, $40m^3/h{\sim}200m^3/h$) considering the CMC (calibration and measurement capability) of the participating laboratories. The purpose of the proficiency test was to find out measurement equivalence of the CMC's between each participating laboratory and the reference testing laboratory (KRISS). The measurement equivalence was tested by the number of equivalence ($E_n$). If ${\mid}E_n{\mid}$ < 1, the measurement equivalence was established. All the participating laboratories passed this proficiency test. 한국인정기구(KOLAS)는 아시아태평양인정협의체(APLAC)에 소속되어 있으며, 측정 결과를 SI 단위로 소급하고 이를 유지시키기 위해 교정기관 인정제도를 운영하고 있다. 2016 년 6 월 현재, 22 개의 기관이 KOLAS 물유량 분야 교정기관으로 지정되어 있다. 이 중 12 개 KOLAS 교정기관들이 한국계량측정협회(KASTO)가 2015 년에 주관한 물유량 숙련도 시험(PM2015-08)에 참가했다. 이번 숙련도 시험은 KOLAS 교정기관들의 교정측정능력(CMC)을 고려하여 3 가지의 유량 범위($3.6m^3/h{\sim}12m^3/h$, $40m^3/h{\sim}80m^3/h$, $40m3/h{\sim}200m^3/h$)에서 실시되었다. 숙련도 시험의 목적은 참가기관들의 CMC 가 기준시험소(KRISS)의 CMC 와 비교하여 측정동등성이 성립하는지 여부를 판단하기 위한 것이다. 측정동등성은 측정동등성지수(number of equivalence; $E_n$)를 산출하여 평가했다. ${\mid}E_n{\mid}$ < 1 일 때, 측정동등성이 확립된다고 판단했다. 이번 시험에서 12 개 KOLAS 교정기관 모두 기준시험소와 측정동등성이 성립함을 확인했다.
전세종(Sejong Chun),윤병로(Byung-Ro Yoon),강웅(Woong Kang),이용봉(Yong-Bong Lee),최해만(Hae-Man Choi) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
This study introduces the research progress of establishing a national standard for liquid flow up to 2000 ㎥/h at KRISS. At first, the WGFF guidelines for CMC uncertainty and calibration report uncertainty are introduced. After that, a mathematical model for a gravimetric flow measurement system is described using two control volumes. Some of experimental results reveal that the gravimetric system attained the measurement uncertainty less than 0.06 % (k = 2) up to 600 ㎥/h. Finally, an on-going strategy for obtaining better uncertainty at 2000 ㎥/h is discussed.
전세종(Sejong Chun),최용문(Yong Moon Choi),최해만(Hae Man Choi),최지철(Ji Chul Choi),홍경기(Kyung Ki Hong),한상우(Sang Woo Han),김웅선(Woong Sun Kim) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
The averaging pitot tube or annubar is widely employed to measure the flow rate of the pollutants discharged from the chimney in many industrial situations. Accurate monitoring of the amount of the discharged pollutants necessitates the annubar calibration, which is usually performed in wind tunnels and the calibration conditions are dependent on the size of the wind tunnel test section. However, there are many situations where annubars are larger than the typical size of wind tunnel test sections. In the present study, a new technique using partial blockage was proposed, enabling calibrations of large annubars in various configurations. The results demonstrated favorable agreements with the original annubar coefficients.
전세종(Sejong Chun),홀거 노박(Holger Nobach),캠 트로피아(Cam Tropea),성형진(Hyung Jin Sung) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
The laser Doppler technique is well-established as a velocity measurement technique of high precision for flow velocity. Recently, the laser Doppler technique has also been used to measure acceleration of fluid particles. Acceleration is interesting from a fluid mechanics point of view, since the Navier Stokes equations, specifically the left-hand-side, are formulated in terms of fluid acceleration. Further, there are several avenues to estimating the dissipation rate using the acceleration. However such measurements place additional demands on the design of the optical system; in particular fringe non-uniformity must be held below about 0.0001 to avoid systematic errors. Relations expressing fringe divergence as a function of the optical parameters of the system have been given in the literature; however, direct use of these formulae to minimize fringe divergence lead either to very large measurement volumes or to extremely high intersection angles. This dilemma can be resolved by using an off-axis receiving arrangement, in which the measurement volume is truncated by a pinhole in front of the detection plane. In the present study an optical design study is performed for optimizing laser Doppler systems for fluid acceleration measurements. This is followed by laboratory validation using a round free jet and a stagnation flow, two flows in which either fluid acceleration has been previously measured or in which the acceleration is known analytically. A 90 degree off-axis receiving angle is used with a pinhole or a slit.
전세종(Sejong Chun),이생희(Saeng Hee Lee),최용문(Yong Moon Choi) 대한기계학회 2010 大韓機械學會論文集B Vol.34 No.3
3-컵 풍속계는 자동기상측정, 환경 모니터링, 풍력 발전에 필요한 풍속을 측정하기 위해 널리 사용되고 있다. 일반적으로 3-컵 풍속계의 회전부를 지지하는 페어링은 오염물질, 진동 또는 돌풍 등의 여러 요인에 의해 마모되기 쉽고 이로 인해 풍속에 대한 출력 특성이 장기적으로 변한다. 따라서 3-컵 풍속계를 주기적으로 교정하여 풍속에 대한 출력 특성을 유지 및 관리해야 한다. 본 연구에서는 3-컵 풍속계가 설치된 현장에서 풍속계를 교정할 목적으로 제트 유동을 이용한 현장용 교정 장치를 제작하였다. 현장용 교정 장치가 3-컵 풍속계를 교정할 수 있는지 확인하기 위해 현장용 교정 장치의 제트 유동 특성을 측정하였다. 현장용 교정 장치를 가지고 5 종류 3-컵 풍속계들을 교정하였고, 풍동에서 3-컵 풍속계를 교정한 결과와 비교하였다. Three-cup anemometers are popular devices for measuring wind speeds in automated weather stations, environmental monitoring systems, and wind turbines. Cup anemometers usually suffer from lack of long-term stability owing to the wear of the bearing systems that support the rotational parts. The bearing systems are susceptible to external pollutants, vibrations, and gusts. Therefore, these anemometers have to be calibrated regularly to maintain the desired characteristics for measuring wind speed. In the present study, a new in-situ calibration system to help reduce cost and save time by calibrating the cup anemometers at the installation site is proposed. A portable in-situ calibrator was fabricated. After the characteristics of this calibrator were verified, it was used to calibrate cup anemometers. Some of the calibration results were compared with the data obtained by wind tunnel testing.
전세종(Sejong Chun),최용문(Yong Moon Choi),최해만(Hae Man Choi),이생희(Saeng Hee Lee) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
Cup anemometers are popular devices for measuring wind speed in an automative weather measuring system, an environmental monitoring system and a wind turbine. The cup anemometers usually suffer from long-term stability by the wear of the bearing system to support the rotational parts. They are susceptible to external pollutants, vibrations or gusts. Therefore it is necessary to have a regular calibration service to maintain the characteristics of cup anemometers measuring wind speed. In the present study, a new type of in-situ calibration system is suggested to save costs and time by calibrating the cup anemometers near the place where they are installed. An in-situ calibrator was fabricated in portable size. After the characteristics of the in-situ calibrator was verified, cup anemometers were calibrated by this device. Some of the calibration results were compared with the data given by the wind tunnel testing.
전세종(Sejong Chun),윤병로(Byung-Ro Yoon),강웅(Woong Kang),권휴상(Hyu-Sang Kwon) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
Clamp-on ultrasonic flow metering can provide a non-invasive and portable means for flow measurement. However, the clamp-on ultrasonic flow metering indicates flow rates with low measurement accuracy at low flow velocity in pipe flows. Typical accuracy of the clamp-on ultrasonic flow metering amounts as low as ±1 % if the flow velocity in a pipe is greater than 0.5 m/s. The accuracy can be greater than ±2 % if the flow velocity is lowered smaller than 0.5 m/s. These shortcomings of the clamp-on ultrasonic flow metering can be overcome by combining two transit times along a Z-shaped and a V-shaped ultrasonic path. This technique is named as combined V/Z clamp-on ultrasonic flow metering. With the water flow standard system in KRISS, this combined technique exhibited intermediate performance between the two flow metering techniques along the Z-shaped and the V-shaped ultrasonic paths.