• 한국해양공학회지
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• 제12권2호통권28호
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• pp.147-152
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• 1998

In this study turbine flowmeters were used to predict volumetric flow rate of each phase in two-phase, gas-liquid, flowing in a vertical tube. To determine volumetric flow rates of two-phase, air-water, flowing vertically upward through the polycarbonate tube(57mm ID-inside diameter), two turbine flow meters were used. For void fraction measurements, two gamma densitometers were used at each location of the turbine flow meter, one at the upstream and the other at the downstream. It was determined that the turbine flowmeter's outputs were a function of actual volumetric flow rate of each of the two phases. A two-phase flow model was developed.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2011년 춘계학술대회논문집
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• pp.596-600
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• 2011

In this numerical analysis, the distortion of flow measurement by inlet velocity profile of orifice flowmeter was investigated. To validate the numerical method, the convergence was monitored and the grid dependency was also checked. realizable k-e model was selected and y+ was about 50 in this calculation. the results shows that the pressure at the pressure tab near pipe wall was changed by inclined inlet velocity profile and it leads to distorted a measurement values of flow through the orifice plate from -3.8% to 9%. Therefore, the fully developed inlet flow was required for accurate flow measurement by orifice flowmeter. If not, the orifice plate installed at wrong location should be re-installed or additional actions should be taken.

• 대한기계학회논문집B
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• 제25권4호
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• pp.561-571
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• 2001

The standard uncertainty of flowrate measurement is obtained by combining that of independent variables. Gravimetric and volumetric method were applied to determine the flowrate and the standard uncertainties of flowrate measurement by both methods were evaluated in accordance with the procedure recommended by International Organization for Standardization. The combined standard uncertainties of determining the flowrate were estimated from the sensitivity coefficient and the standard uncertainty of independent variables. For practical application, the methods for evaluating and expressing uncertainty in flow measurement were discussed. It was found that the uncertainties of the weighing and time measurement in gravimetric method, the volume and time measurement in volumetric method have dominant influence on that of flowrate measurement. With the quantitative analysis of the sensitivity coefficient, the contribution of the each variable uncertainty to the combined standard uncertainty of flowrate measurement is shown clearly.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2005년도 연구개발 발표회 논문집
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• pp.150-157
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• 2005

Generally, the flow hunting is observed in almost all of the orifice meters but the intensity of the flow hunting is different at each metering system. So, we were getting some Questions as follows; why such a difference occurs and whether it influence to metering error rate or not. To investigate the flow hunting characteristics, we are trying to examine the flow characteristics around the orifice meter when the transient flow or pressure is generated at after the PCV(Pressure Control Valve) by 3D CFD method. And we have compared numerical results with experimental results at M - PCV station in order to clarify the relations with both the metering-pipeline diameter and flow rate. Finally, we can show some major factors influencing to the flow hunting and propose some correcting scheme of the flow hunting equation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.364-364
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• 2008

유한요소해석을 통하여 수도계량기용 삽입형 초음파 유량계 압전 트랜스듀서의 설계를 실시하고 이를 평가하였다. 상용 해석프로그램인 PzFlex를 사용하여 센서의 transient 해석을 실시하였다. 이를 통해 각 구성부품의 재질 및 형상 변수를 결정하였다. 이를 기준으로 트랜스듀서를 제작하였으며, 두께모드 중심주파수가 1.2MHz가 되도록 직경 10mm의 압전소자를 이용하였다. 시뮬레이션을 통해 $25^{\circ}$의 방사각으로 음향파가 발생되도록 트랜스듀서를 설계, 제작한 후, 트랜스듀서의 전기적, 기계적 특성을 평가하였다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.154-160
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• 2003

Multi-path ultrasonic flowrate measuring technology is being received much attentions from a variety of industrial fields to exactly measure the flowmeter. Multi-path ultrasonic flowmeter has much advantage since it has no moving parts and not occurred pressure loss. It offers good accuracy, repeatability, linearity and Tum-down ratio can measure over 1:50. The present study investigates flowrate integration errors using weighting factors. A theoretical flow model uses power law to describe a fully developed velocity profiles and wall roughness changes. The methods of weighting factor simulate three configurations of measuring location of gaussian, chebyshev and tailor method. The obtained results show that many chord arrangements are not affected for wall roughness changes and can measure accurate flowrate.

• 대한기계학회논문집B
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• 제27권12호
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• pp.1699-1707
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• 2003

Coriolis mass flowmeter(CMF), which can measure the mass flow directly, is getting rapid attention for the industrial and custody transfer purpose. In order to study the characteristics and the applicability of CMF, it is tested with the national flow standard system. Two types of sensing tube, U-type and straight type, are employed in the test. Water, spindle oil and viscosity Standard Reference Material whose viscosities are 1, 20 and, 67 $\textrm{mm}^2$/s, respectively, are studied. It is shown that the linearity of CMF is getting deteriorated as the fluid viscosity increases, which is due to the zero drift and the relaxation time of the fluid. To test its applicability in the case of high pressured gas, it is calibrated using compressed air, It shows 1∼l.6 % deviations compared to the calibration results using water. It concludes that the fluid velocity in CMF should be lower than the sonic velocity. In addition, the effects of the vibration from the pipeline and pump on CMF as well as the long term stability are studied.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2009년도 학술발표회 초록집
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• pp.1437-1441
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• 2009

기존의 ADCP는 1m 이하의 저수심 지점에서 측정이 불가능하였으며, 유속계 측정장비는 저유속 지점에서 측정이 불가능한 경우가 많아 유량측정에 어려움을 겪는 경우가 많다. 최근 RDInstruments에서 제작한 StreamPro는 1m 이하의 수심, 0.1m/s 이하의 유속에서 측정이 가능하기 때문에 이를 이용하면 저수심, 저유속 지점에서 유량측정이 가능하다. ADCP를 이용한 측정의 경우 보다 정확한 측정성과를 얻기 위하여 유속의 50% 속도로 이동하며 측정하여야 하며, 4회 측정유량값의 상대오차가 5% 이내일 때 그 평균값을 측정치로 한다. 그러나 0.1m/s 이하의 유속이 나타나는 지점은 0.05m/s 이하의 속도로 이동하며 측정을 실시하여야 하며 이 경우 측정시간이 너무 길어지는 문제가 있다. 따라서 본 연구에서는 StreamPro를 이용한 유량측정의 적용성 평가와 함께 적절한 신뢰도를 얻을 수 있는 실용적인 측정회수 분석을 실시하였다. StreamPro를 이용한 측정성과의 적용성을 평가하기 위하여 StreamPro와 동시에 Price 유속계 측정을 실시하여 이를 비교하였다. 실용적인 적정 측정회수 분석은 측정유량의 상대오차를 Student-t분포에 적용하여 불확실도값을 기준으로 분석하였다. StreamPro와 Price 유속계 측정성과를 비교한 결과, 평균 상대오차가 약 3.5%로 적절한 값을 나타냈으며, 저수심, 저유속 지점에서의 실용적인 측정회수는 약 11회로 나타났다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.154-161
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• 2000

As a mass flow controller is widely used in many manufacturing processes for controlling a mass flow rate of gas with accuracy of 1%, several investigators have tried to describe the heat transfer phenomena in a sensor tube of an MFC. They suggested a few analytic solutions and numerical models based on simple assumptions, which are physically unrealistic. In the present work, the heat transfer phenomena in the sensor tube of the MFC are studied by using both experimental and numerical methods. The numerical model is introduced to estimate the temperature profile in the sensor tube as well as in the gas stream. In the numerical model, the conjugate heat transfer problem comprising the tube wall and the gas stream is analyzed to fully understand the heat transfer interaction between the sensor tube and the fluid stream using a single domain approach. This numerical model is further verified by experimental investigation. In order to describe the transport of heat energy in both the flow region and the sensor tube, the Nusselt number at the interface between the tube wall and the gas stream as well as heatlines is presented from the numerical solution.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2011년도 학술발표회
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• pp.113-117
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• 2011

"환경과 개발"을 함께 고려하는 지속 가능한 유역관리제도 정착을 위해 도입된 수질오염총량관리제도(TMDL)가 총 8년(1차: 2004~2010년, 2차: 2011~2015년)이라는 세월이 흘렀다. 또한 이 제도의 효율적인 추진을 위해 낙동강수계 총 41개 단위유역별 모니터링 사업(유량 및 수질조사)이 지속적으로 수행되고 있다. 이와 더불어 단위유역 내 지자체간 오염배출부하 기여도 분석을 위해 각 소하천들 중 주요 시 군 경계 소하천 유역 46개 지점을 선정하여 신규 소하천 모니터링 사업을 2010년 9월부터 수행하고 있다. 소하천 모니터링 사업의 목적은 오염총량관리 단위유역 내 시 군 경계 지점에 대하여 모니터링(유량 및 수질)을 효율적으로 실시하여 소유역내 유량/수질의 변화추세를 파악하고 오염총량관리제 기본 시행계획 수립 및 이행평가 등을 위한 기초 자료 제공 및 활용에 그 목적을 두고 있다. 본 연구는 2010년에 낙동강수계 소하천 모니터링 사업에서 수행된 소유역 분석결과 및 유량/수질 측정성과에 대한 평가 및 소하천별 수질오염현황에 대해 소개하고자 한다.