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최영도(Young-Do Choi),쿠로카와준이치(Junichi Kurokawa),이영호(Young-Ho Lee) 한국유체기계학회 2007 유체기계 연구개발 발표회 논문집 Vol.- No.-
The purpose of present study is not only to develop a simple method to improve pump performance but also to suppress the occurrence of cavitation in the centrifugal pump by use of J-Groove. Semi-closed impeller is a newly developed centrifugal impeller in which inlet shape of the front shroud is modified. J-Groove is a shallow groove installed on the casing wall in the meridional direction. The results show that the application of the new type impeller of semi-closed impeller with J-Groove to a centrifugal pump has proved its effectiveness as a useful countermeasure of the unstable pump performance and cavitation. The combination of semi -closed impeller and J-Groove can be applied successfully and improves both the pump performance and suction performance.
극저비속도영역에서 원심펌프의 불안정성능 개선에 관한 연구
최영도(Young-Do Choi),쿠로카와준이치(Junichi Kurokawa),김유택(You-Taek Kim),이영호(Young-Ho Lee) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
The ratio of disk friction loss in a centrifugal pump is very large for the total pump oss in the range of very low specific speed. Therefore, impeller radius should be shortened to increase the pump efficiency because the disk friction loss is proportional to the fifth power of impeller radius. In order to compensate the decreased head by the shortened impeller radius, vane angle at impeller outlet should be increased. However, as the vane angle at impeller outlet becomes larger, performance instability occurs at low flow rate regions. In this study, J-Groove is adopted to suppress the performance instability and detailed examination is performed for the influence of the J-Groove on the pump performance. The results show that J-Groove gives good effect on the suppression of performance instability. Moreover, as J-Groove increases pump head considerably, the pump size can be smaller.
기관지내시경을 통한 Endobronchial Watanabe Spigot (EWS) 삽입으로 치료한 기관지흉막루 1례
최영인 ( Young In Choi ),조진희 ( Jin Hui Cho ),심진영 ( Jin Young Shim ),신승수 ( Seung Soo Sheen ),오윤정 ( Yoon Jung Oh ),박주헌 ( Joo Hun Park ),황성철 ( Sung Chul Hwang ),이성수 ( Sung Soo Lee ) 대한결핵 및 호흡기학회 2005 Tuberculosis and Respiratory Diseases Vol.58 No.4
유아교육기관에서의 실내공기질 조사 및 실내활동에 따른 입자상오염물질의 농도특성
최영아(Young-A Choi),이태정(Tae-Jung Lee),김동술(Dong-Sool Kim) 한국실내환경학회 2006 한국실내환경학회지 Vol.3 No.3
This study was performed to investigate indoor air quality and to characterize the concentration of particulate matters followed by human activities in preschool classrooms. Concentrations of PM<SUB>10</SUB>, PM<SUB>2.5</SUB>, and PM₁ were measured every 5-minute intervals by means of a dust monitor adopting the principle of light scattering. Two mini-volume air samplers were used further to measure the I/O concentration ratio of PM₁? and to calibrate the dust monitor since the photometric method often exaggerates the mass of fine particles. The calibration factor in the study environment was determined as 0.64. In the preschool classrooms, the ranges of average indoor PM<SUB>10</SUB>, PM<SUB>2.5</SUB>, and PM₁ concentrations were 51.5~117.6, 21.5~98.4, and 16.2~84.5 ㎍/㎥, respectively, while that of I/O concentration ratio was 0.8~1.3. Based on correlation analysis among various environmental parameters, PM₁ was slightly correlated with humidity (r=0.416, p<0.01). However, outdoor PM<SUB>10</SUB> was strongly related with indoor PM<SUB>2.5</SUB> (r=0.95, p<0.01), with PM₁ (r=0.94, p<0.01), and with PM<SUB>10</SUB> (r=0.84, p<0.01). The trend of PM<SUB>2.5</SUB> and PM₁ concentrations appeared to be very similar unlike the case of PM<SUB>10</SUB>. Since the elevated coarse particle concentration (2.5㎛<dp<10㎛) and the average PM<SUB>2.5</SUB>/PM<SUB>10</SUB> ratio were highly dependent on classroom activities, the parameter of PM<SUB>2.5</SUB>/PM<SUB>10</SUB> ratio was intensively studied with 7 different indoor activities in the preschool classrooms.