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RISS 인기검색어
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- 저자 : 최용문 ( Choe Yong Mun ) (검색결과 3 건)
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최용문,박경암,차지선,최해만,윤복현,Choe, Yong-Mun,Park, Gyeong-Am,Cha, Ji-Seon,Choe, Hae-Man,Yun, Bok-Hyeon 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.11
A sonic nozzle is used as a reference flow meter in the area of gas flow rate measurement. The critical pressure ratio of sonic nozzle is an important factor in maintaining its operating condition. ISO9300 suggested the critical pressure ratio of sonic nozzle as a function of area ratio. In this study, 13 sonic nozzles were made by the design of ISC9300 with different half diffuser angles of 2。 to 8。 and throat diameters of 0.28 to 4.48 mm. The test results of half diffuser angles below 8。 ar quite similar to those of ISO9300. On the other hand, the critical pressure ratio for the nozzle of 8。 decreases by 5.5% in comparison with ISO9300. However, ISO9300 does not predict the critical pressure ratio at lower Reynolds numbers than 10(sup)5. Therefore, it is found that it is a better way for the flow of low Reynolds number to express the critical pressure ratio of sonic nozzle as a function of Reynolds number than area ratios. A correlation equation of critical pressure is introduced with uncertainty $\pm$3.2 % at 95% confidence level.
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최해만,박경암,최용문,Choe, Hae-Man,Park, Gyeong-Am,Choe, Yong-Mun 대한기계학회 2001 大韓機械學會論文集B Vol.25 No.12
Measurement uncertainty should be evaluated according to ISO/IEC 17025. In Flow measurement area, uncertainty evaluation scheme was applied to the reference flow meter, sonic nozzle. Uncertainty was calculated by evaluating various uncertainty factors affected in flow measurement. The expanded uncertainty(U) of the sonic nozzle was 2.1$\times$ 10$^{-3}$ (confidence level of 95 %). This evaluation example will be useful in flow measurement uncertainty determination of other flow meters.
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유전체 (Si3N4/SiO2/Si3N4) 멤브레인 위에 제작된 크로멜-알루멜 열전 유량센서
이형주 ( Lee Hyeong Ju ),김진섭 ( Kim Jin Seob ),김여환 ( Kim Yeo Hwan ),이정희 ( Lee Jeong Hui ),최용문 ( Choe Yong Mun ),박세일 ( Park Se Il ) 한국센서학회 2003 센서학회지 Vol.12 No.3
Si₃N₄/SiO₂/Si₃N₄ 열차단막을 이용한 크로멜-알루멜(chromel-alumel) 열전(thermoelectric) 유량센서를 제작하였다. 백금 박막 히터의 저항온도계수는 약 0.00397/℃이었고, 크로멜-알루멜 열전쌍(thermocouple)의 Seebe다 계수는 약 36 μN/K이었다. 기체의 열전도도가 증가할수록 유량센서가 나타내는 열기전력은 감소하였으며, 히터의 온도가 증가하거나 히터와 열전쌍 사이의 간격이 감소할수즉 유량센서의 N₂유량에 대한 심도는 증가하였다. 히터 전압을 약 2.5 V로 하였을 때 유량센서의 N₂ 유량에 대한 감도는 약 1.5 ㎷/sccm^(1/2)이었고, 열 응답시간은 약 0.18초이었다. 크로켈-알루켈 열전 유량센서의 유량감도에 있어서 신형 범위가 Bi-Sb 유량센서의 것보다 더 넓게 나타났다. A chromel-alumel thermoelectric flow sensor using Si₃N₄/SiO₂/Si₃N₄thermal isolation membrane was fabricated. Temperature coefficient of resistance of thin film Pt-heater was about 0.00397/℃, and Seebeck coefficient of chromel-alumel thermocouple was about 36 ㎶/K. The sensor showed that thermoelectric voltage decreased as thermal conductivity of gas increased, and N₂-flow sensitivity increased as heater voltage increased or the distance between heater and thermocouple decreased. When heater voltage was about 2.5 V, N₂-flow sensitivity and thermal response time of the sensor were about 1.5 ㎷/sccm^(1/2) and 0.18 sec., respectively. Linear range in flow sensitivity of the flow sensor was wider than that of Bi-Sb flow sensor.
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