• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 1999년도 유체기계 연구개발 발표회 논문집
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• pp.109-113
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• 1999

Thermal mass flow meter (TMF) is used measuring the small mass flow rate of gases. Generally, flow rate measuring accuracy of TMF is $\pm2{\%}$ of full scale. TMF is manufactured for specified working pressure and specified working gas by customer. If it were applied for different working pressure and gases, flow rate measurement accuracy decreased dramatically. In this study, a TMF tested with three different gases and pressure range of 0.2 MPa to 1.0 MPa. Effect of specific heat cause to increase flow measurement error as much as ratio of specific heat compare with reference gas. Pressure change cause to increase flowrate measurement deviation about $-0.2{\%}$ as the working pressure decreased 0.1 MPa.

• 한국유체기계학회 논문집
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• 제2권2호
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• pp.19-26
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• 1999

Thermal output in a nuclear power plant is verified with calorimetric heat balance on the secondary plant. The calorimetry involves the precise measurement of the feedwater flow rate. However, the correct indication of feedwater flow rate obtained by a pressure-difference measurement across a venturi can be affected by instrument errors, fouling or a poorly developed velocity profile. This can result in an inaccurate mass flow rate and consequently an inaccurate estimate of power. The purpose of this study is to develop verification methods with accuracy better than $0.5\%$ for high precision flow measurement to be used for measuring feedwater flow rate. This chemical tracer method is a testing process that uses tracers which can be applied to quantify losses in electrical output due to the incorrect measurements of feedwater flow rate. And this system has good response to the variation of the flow rate. Accuracy of better than 0.5 percent can be expected for feedwater flow measurement, providing that the system can be stabilized during the test. This methodology is applicable to other flow systems well.

• 대한기계학회논문집A
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• 제26권8호
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• pp.1552-1564
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• 2002

Meter-in, meter-out and bleed-off circuits are widely utilized in order to adjust the speed of a hydraulic actuator by using a flow control valve and in order to regulate the pressure of a hydraulic volume by using a simple on-off valve. In these circuits, a relief valve serves either to maintain constant system pressure or to protect the system from over-pressure loading. The relief valve of a bleed-off circuit is the second case frequently undergoing on-off action during operation. It makes the analysis of the pressure control characteristics of the circuit highly difficult. In this paper, steady-state flow rate, pressure, heat loss and efficiency of the three circuits are reexamined and basic experiments far obtaining the characteristics of a pump and relief valve are conducted. Finally, simple empirical first-order dynamic models of decreasing and increasing pressure were separately proposed and verified by comparison with experiment. As the result, the basis for the theoretical analysis of the pressure control characteristics of a bleed-off circuit using a simple on-off valve is established.

• 한국환경과학회지
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• 제13권7호
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• pp.697-701
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• 2004

Most of methane gas result from waste matter in landfill, therefore the persons concerned take an increasing interest in management of gases in landfill. Infrared Gas Analyzer was used to measure components of gases, $CH_4,$ $CO_2,$ $O_2,$ through gas exhausted pipe. To measure amount of the gas flow meter(Portable Hot-Line Current Meter) was used and it was set at right angles with direction of the flow. In this research the total amount of methane gas produced in Beck-Suk Landfill was calculated through FOD method suggested by IPCC. This research found that in Chon-An Beck-Suk Landfill anaerobic resolution was made actively and the amount of methane gas produced there was 54.14%, which is higher than common figure, 50%, in other researches. The components of reclaimed waste matter, especially, organic waste matter can have a great effect of the amount of the greenhouse gases produced in landfill. We can expect that the amount of greenhouse gas will decrease from 2005, when it will be prohibited from carrying kitchen refuse and sludge into landfill.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2000년도 춘계학술대회논문집
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• pp.91-98
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• 2000

Derivation of stage-discharge relationship and characteristics for Yangsan river is presented in this paper. This research has been conducted as the second one after the first trial of 1997. The determination of discharge at a Yangsan river gauging was best made by measuring the flow velocities with a current meter and rod float. The rating curve obtained through 52 stage-discharge measurements on Yangsan river basin in 1999 is represented by Q=15.3540-140.6076H+182.44372$H^2$, which is discovered to be most excellent among other curves in reliability analysis. The capability of the observed stage-discharge data for Yangsan river was tested by HEC-RAS program, and its capability to reproduce discharge was investigated and compared with the computational results. Rating curve stability is determined on the basis of deviations in the stage-discharge relationship, utilization of specific gauge, and absolute differences between sequential stream flow measurements and an analysis residuals. Therefore it seems necessary to research method to obtain rating curve in a rigorous and accurate manner.

• 분석과학
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• 제7권3호
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• pp.349-359
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• 1994

천연가스 중의 부취제 농도를 분석하기 위한 기체 크로마토그래피 방법에 대하여 연구하였다. TBM(tertiarybutylmercaptan) 및 THT(tetrahydrothiophene)를 포함한 8종의 부취제를 OV-101 컬럼상에서 거의 완전히 분리하였다. 수소 유속, 공기 유속 및 검출기 온도와 같이 FPD의 응답에 영향을 미치는 몇 가지 상호 관련된 파라미터들의 최적 조건을 구하였다. TBM과 THT의 검정곡선을 투과한 장치를 이용하여 작성하였다. 이러한 분석방법을 천연가스 공급관 내의 혼합 부취제인 TBM과 THT를 정량하는 데 적용하였다. 부취수준과 부취제 농도와의 상관관계를 구하기 위한 냄새 측정기의 유용성에 대하여 알아보았다.

• 한국수소및신에너지학회논문집
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• 제29권1호
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• pp.32-40
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• 2018

There has been an measuring errors between state of charge (SOC; kg) value and mass flow meter (MFM) value in dispenser for hydrogen refueling station. Finally, we observed average 15.5% weight difference between these two values and the MFM readings show a 15.5% higher readout of the SOC readings. Each car was charged with average 2.66 kg of hydrogen fuel during this period. In the initial charging of the day shows less measuring value than the final charging with the maximum 0.038 kg times number of filling. There is no effects of atmosphere temperature change for the hydrogen filled weight during one full year such as January's cold winters and August's hot summers.

• 한국환경과학회지
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• 제22권5호
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• pp.581-589
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• 2013

Surface Image Velocimetry(SIV) is an instrument to measure water surface velocity by using image processing techniques. Since SIV is a non-contact type measurement method, it is very effective and useful to measure water surface velocity for steep mountainous streams, such as streams in Jeju island. In the present study, a surface imaging velocimetry system was used to calculate the flow rate for flood event due to a typhoon. At the same time, two types of electromagnetic surface velocimetries (electromagnetic surface current meter and Kalesto) were used to observe flow velocities and compare the accuracies of each instrument. The comparison showed that for velocity distributions root mean square error(RMSE) was 0.33 and R-squared was 0.72. For discharge measurements, root mean square error(RMSE) reached 6.04 and R-squared did 0.92. It means that surface image velocimetry could be used as an alternative method for electromagnetic surface velocimetries in measuring flood discharge.

• 한국수소및신에너지학회논문집
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• 제28권3호
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• pp.279-286
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• 2017

Korea government decides to build one hundred hydrogen refueling stations (HRS) until 2020 and tries to disseminate HRS and boosts HRS market in korea. Naepo HRS in chungnam province has been operated for last one full year of 2016 and recorded 2,520 times full charge for the hydrogen fuel cell powered vehicles and total 6,016 kg hydrogen fueling for the 25 units of hydrogen fuel cell powered vehicles. Raw fuel of hydrogen from tube trailer measured by pressure, converting into weight of hydrogen and shows 19.6% surplus with final charged weight by dispenser. This result is caused measuring errors. Measured charged errors between dispenser and Mass flow meter was determined 13.13%.

• Archives of Reconstructive Microsurgery
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• 제13권1호
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• pp.36-42
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• 2004

Materials and Methods: We studied 50 cases of peroneal perforating branch about branching pattern, course, length of vascular pedicle, and perforating level of the perforating cutaneous branches from Oct. 1985 to November 2003 by doppler flow meter and intraoperative findings. Results: 1) The perforating cutaneous branches were classified into four types, the Straight Branch (27cases), the Proximal Oblique Branch (11cases), the Branch from Muscular Artery (10cases), the Distal Oblique Branch(2 cases) respectively. The most common patten was Straight Branch, that was 54%. 2) There were 3 pathways of these branches, the most common one passed between the Soleus and Peroneus muscles(34 cases, 68%) 3) The length of vascular pedicle in Buoy Flap was variable from from 3 cm to 15 cm, but 32 cases(64%) were distributed between 5 cm and 6 cm. 4) The perforating level of branches were 5.9 cm in average from fibular neck to subcutaneous perforator artery 5) Peroneal Buoy Flap in possible to reconstruct both seperated bone and skin defect in some distance by One-Stage Operation and we can harvest maximal $8{\times}16cm$ sized flap in one perforating artery. If we include more two perforating artery, we get more wide flap which can cover large defect.