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소닉노즐을 이용한 천연가스 유량측정에서 임계유동인자 계산 및 국제비교 결과
하영철,허재영,Ha, Youngcheol,Her, Jaeyoung 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.7
The sonic nozzle is widely used as reference device for calibrating flowmeters In gas flow measurement and its use requires the Critical Flow Factor(CFF) based on the thermodynamic properties of the gas at the nozzle throat. ISO-9300 provides the calculating method of the factor. But since the CFF from this method show an error over ${\pm}0.5%$ In specific conditions and of ${\pm}0.1{\sim}{\pm}0.2%$ in common Natural Gas(NG) custody transfer condition. this method cannot be applied for gas flow measurement with sonic nozzle. Each research bodies or organizations of the world have joined in order to calculate the CFF more accurately. They have performed these works using their own method and compared the results with each other under the management of ISO. KOGAS have joined those works, because the high-pressure natural gas flow calibration facility of KOGAS will be constructed in late 1999, and then had necessities to calculate a CFF accurately. The calculation method of KOGAS was using the equation of state from AGA-8('94), high accuracy model of ideal gas properties and the solutions of thermodynamic equations. The evaluation results have had a very good consistency within ${\pm}0.05%$ in most NO custody transfer conditions compared to the speed of sound for methane and also shown that the CFF was within ${\pm}0.1%$ compared to the results of other works of the world.
천연가스 계량배관 내$\cdot$외의 온도차가 계량오차에 미치는 영향에 관한 연구
하영철,이철구,장승룡,이강진,Ha Youngcheol,Lee Chulgu,Chang Seungyong,Lee Kangjin 한국가스학회 1998 한국가스학회지 Vol.2 No.1
단열이 되어 있지 않은 천연가스 계략배관에서 배관 내$\cdot$외의 온도차로 인한 오리피스 유량계 오차를 정성적으로 실험하였다. 고려된 주요 인자는 유속과 대기온도이며 태양복사열도 일부 고려되었다. 실험결과 유량이 극히 작고, 배관 내$\cdot$외의 온도차가 큰 하절기 유동조건에서도 그다지 큰 오차는 발생하지 않는 것으로 분석되었다. Experiments had been conducted Qualitatively regarding flow measurement errors of orifice flowmeter due to temperature difference between the inside and outside the natural gas meter-run in case of no pipe insulations. The primary factors considered in this study are fluid velocity and surrounding temperature. In addition, a portion of thermal radiation due to the sun was involved as a factor. The results showed that the considerable errors were not detected even in conditions of low flow rates and large temperature difference between the inside and outside the meter-run.
고층건축물의 비틀림방향 변동풍력의 특성에 관한 실험적 연구
하영철(Ha Young-Cheol),김동우(Kim Dong-Woo),길용식(Kil Yong-Sik) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
This study aims at verifying characteristics of torsional fluctuating moment coefficient and power spectral density, which is needed to estimate torsional response of tall buildings. In order to estimate characteristics, the wind tunnel tests have been conducted on 52 types aero-elastic model of the rectangular prisms with various aspects ratios, side ratios and surface roughness in turbulent boundary layer flows. In this paper, characteristics of torsional fluctuating wind force are briefly discussed and then these results were mainly analyzed as a function of the aspects ratios and side ratios of buildings.
건축물의 높이 및 변장비 변화에 따른 각주형 건축물의 평균풍압분포 특성에 관한 연구
하영철(Ha Young-Cheol),박재형(Park Jae-Hyeong),황성권(Hwang Sung-Kwon) 대한건축학회 2009 大韓建築學會論文集 : 構造系 Vol.25 No.4
This study summarizes basic results on the characteristics of mean wind pressure distribution on rectangular buildings with various heights and side ratio which is needed to estimate reasonable wind load of buildings, through simultaneous multi-point wind pressure test. 12 types of rectangular wind pressure test models with various heights and side ratios have been made for this study. Wind pressure tests are conducted on the Boundary Layer Wind Tunnel at Kumoh National Institute of Technology. The characteristics of mean wind pressure distribution with respect to various heights and side ratios of buildings are analyzed as a function of the aspect ratios and side ratios. The result shows that wind pressure is decreased as the aspect ratio decreases and wind pressure distribution is significantly effected by side ratios on low-rise buildings.
공정시스템,이동현상,화학공정안전 : LNG 밀도계를 이용한 저장 탱크 내 LNG 발열량 실시간 측정방법에 관한 연구
하영철 ( Young Cheol Ha ),이성민 ( Seong Min Lee ) 한국화학공학회 2011 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.49 No.1
가스호환성에 문제가 있는 저열량의 LNG가 도입되기 시작한 것은 2005년 동절기부터이다. 이러한 LNG의 도입량은 매년 증가하고 있으며 향후에는 극저열량(발열량 ≤ 9,500 kcal/Nm3)의 CBM(Coal Bed Methane), Shale LNG도 대량 도입될 예정에 있다. 따라서 호환 가능한 발열량의 가스를 인수기지에서 송출하기 위해서는 저장 탱크별 LNG 발열량을 실시간으로 모니터링할 수 있는 방법이 필요하게 되었다. 본 연구에서는 이러한 방법의 일환으로 저장 탱크 내설치된 밀도계를 이용하여 LNG 발열량을 실시간으로 측정할 수 있는 방법을 개발하고자 하였다. 이를 위해 액상 LNG 와 발열량 간의 정밀·정확한 상관식을 도출하고 이 방법의 불확도를 계산하였으며 또 인수기지 내 발열량 측정 시스템을 시험 구축하였다. 본 방법의 유효성을 확인하기 위해 현장 LNG 분석데이터와 비교하였으며 그 결과 0.17~0.47% 정도의 편차를 확인하였다. The low caloric LNG, which didn`t meet the gas interchangeability of Korea, has been imported from 2005 winter season. Amount of this LNG imports has been increased from year to year. In the near future, very low caloric LNG (calorific value ≤ 9,500 kcal/Nm3) such as CBM, Shale LNG will be imported large amounts. For this reason, we need a method for monitoring live calorific values(CV) of LNG in each storage tank to supply gasified LNG with interchangeable CV at LNG receiving terminal. This study was conducted to develope the method for measuring the live CVs of LNG in each storage tank using LNG densitometer. For this purpose, the accurate correlation between CV and density of LNG was derived and the uncertainty of this method was evaluated and also the measuring system for CVs was constructed at LNG receiving terminal. To verify this method, the results of measurement using this method were compared with the field data of LNG analysis and the results showed that the deviations were 0.17~0.47%.