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압력, 풍속 및 습구온도계의 크기가 건습구습도계를 이용한 상대습도 측정에 미치는 영향
지대성,김승태,박찬복,Chi, D.S.,Kim, S.T.,Park, C.B. 대한설비공학회 1990 설비공학 논문집 Vol.2 No.2
When the relative humidity is measured with an aspirated psychrometer, three factors, which affect the measurement of relative humidity, are atmospheric pressure, the size of wet element and the wind velocity. This paper investigated the effects of the above three factors, and the computer code was developed in order to enhance the accuracy of the relative humidity measurement. As results, it is found that the relative humidity decreases by 6%RH with increasing atmospheric pressure from 650 mbar to 1100 mbar. It is found that the relative humidity drops down when the size of the wet element increases, though the effect of the size of the wet element is not significant. Finally, relative humidity increases with the increasing wind velocity. The difference between the psychrometic table in the present KS and the present results is about 2%RH maximum. As a conclusion, the three factors mentioned above should be considered in order to secure accurate measurement of relative humidity.
지대성(Daesung Chi) 한국유체기계학회 1999 유체기계 연구개발 발표회 논문집 Vol.- No.-
Thermal mass flow meter was developed using principle of convective heat transfer. The advantage of thermal mass flow meter is measuring mass flow directly, therefore, it is not required to use densitometer or temperature/pressure and DP gages. The final accuracy of this thermal mass flow meter is ±1.0% or better, reproducibility is ±0.2%, and the response time is 600 ㎳. The thermal mass flow meter was developed from a single point to multi-points (maximum is 9 points), and the number of points is determined according to desired accuracy and size of piping/duct. Since this thermal mass flow meter adopted microprocessor based design, it is intrinsically accurate, self-error detectable, and has self-diagnosis function. The applications of this thermal mass flow meter are for measurement and control of HVAC air flow, other gas flow, and liquid flow.
Microwave Determination of Moisture
Nham, H.S.,Choi, B.I.,Chi,D.,Park, C.B.,Park, N.S.,Kim, M.W. 경북대학교 센서기술연구소 1991 센서技術學術大會論文集 Vol.2 No.1
We have developed a microwave method of moisture determination of several materials in free space. A bridge technique at the frequency of 9.5 GHz has been employed to determine the moisture content of building sand, pine wood etc.. It can be modified for continuous and non-destructive measurement of moisture contents of non-metallic materials such as coal, pulp, foods, building materials and so on. The possibility of developing moisture profile measurement system (i.e, microwave imaging technique) will be examined.
원추형 오리피스의 유출계수와 캐비테이션에 관한 실험적 연구
김병찬,윤병옥,박복춘,조남오,지대성,정백순,박경암,Kim, Byeong-Chan,Yun, Byeong-Ok,Park, Bok-Chun,Jo, Nam-O,Ji, Dae-seong,Jeong, Baek-Sun,Park, Gyeong-Am 대한기계학회 1997 大韓機械學會論文集B Vol.21 No.10
The high pressure drop is frequently required in the by-pass line of the pump or of the heat exchanger in power plants. However, cavitation produced by a high pressure drop could damage the pipe and pump blades. Conical orifices are adopted to reduce cavitation due to high pressure drop. The discharge coefficients of conical orifice plates were measured by weighing method in the standard water flow system. The discharge coefficients were larger when the ratios of thickness of orifice edge to throat diameter were larger. The noise generated from a conical orifice due to cavitation was measured with a sound level meter and a hydrophone. With increasing the bore diameter of the orifice, the sound pressure level or the noise level due to cavitation became higher. The noise level was suddenly increased at the inception of cavitation.