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최영석,심재혁,강신형,Choi, Young-Seok,Shim, Jae-Hyeok,Kang, Shin-Hyoung 한국유체기계학회 1999 한국유체기계학회 논문집 Vol.2 No.1
In this study, the performance prediction programs for centrifugal pumps are developed. To estimate the losses in the centrifugal pump impellers, a two-zone model and TEIS(two elements in series) model are applied to the program. The basic concept of a two zone model considers the primary zone that is an isentropic core flow and the secondary zone that has a non-isentropic region at the impeller exit. The flow goes through two different zones and is mixed out at the impeller exit and the mixing process occurs with an increase in entropy, a decrease in total pressure. The level of the core flow diffusion in an impeller was calculated using TEIS(two elements in series) model. The effects of various parameters which are used in this program on the prediction of head and efficiency are discussed. The correlation curves used to select the effectiveness of the primitive TEIS model were suggested according to the specific speed of the centrifugal pumps.
최영석,이경용,이창한,이종훈,Choi, Young-Seok,Lee, Kyoung-Yong,Lee, Chang-Han,Lee, Jong-Hun 한국유체기계학회 2003 한국유체기계학회 논문집 Vol.6 No.2
ADC (Automatic Discharge Connector) is commonly used for the easy maintenance of the submersible pumps. However, the small gap between the flange of the base plate and that of the pipe due to the head rise, the flow momentum change and the mis-installation make a leakage flow that may be a great loss to the pumping system. In this study, the performance degradation was predicted with the simple leakage flow model through the gap. The newly developed ADC was tested, and the leakage performance was compared with the old one and also no-leakage piping system. The newly developed ADC reduced the leakage flow in a satisfactory way in comparison with the old model.
최영석,이용갑,홍순삼,강신형,Choi, Young-Seok,Lee, Yong-Kab,Hong, Soon-Sam,Kang, Shin-Hyung 한국유체기계학회 2001 한국유체기계학회 논문집 Vol.4 No.1
A commercial CFD code is used to compute the 3-D viscous flow field within the impeller of a centrifugal pump. Several preliminary numerical calculations are carried out to determine the influence of the parameters such as the grid systems, the numerical schemes, the turbulence models and the shape of the vaneless diffusers at the design flow rate. The results of the preliminary study are used for the calculation of the off-design flow conditions. The circumferentially averaged results such as the radial and tangential velocities, the exit flow angle, the slip factor, the static pressure and the total pressure are compared with the experimental data at the impeller exit to discuss the influence of the prescribed parameters.
최영석,김덕수,윤준용,Choi Young-Seok,Kim Deok-Su,Yoon Joon-Yong 한국유체기계학회 2006 한국유체기계학회 논문집 Vol.9 No.4
In this study, the effect of flow settling means on the performance of fan tester were numerically investigated by using a computational fluid dynamics(CFD). The airflow rate was calculated from the pressure differential across a flow nozzle in the measuring plane and the flow settling means were generally installed in the chamber of the fan tester to provide proper airflow patterns ahead of the measuring plane. The predicted nozzle differential pressures with uniform inlet velocities were compared with the values of the ANSI/AMCA 210-99 to verify the performance of the commercial CFD code CFX 5.6. The influence of flow settling means on the measurement of airflow rate in a fan tester were discussed with various porosities and inlet jet velocities. The results obtained show that the proper band of porosities exist to meet the AMCA standard in a specified inlet jet velocity.
최영석,이경용,강신형,Choi, Young-Seok,Lee, Kyoung-Yong,Kang, Shin-Hyoung 한국유체기계학회 2003 한국유체기계학회 논문집 Vol.6 No.2
The periphery pump (or regenerative pump) has been generally applied in the automotive fuel pump due to their low specific speed (high heads and small flow rate) with stable performance curves. In this study, the performance prediction of side channel type periphery pumps has been developed. The prediction of the circulatory flow rate is based on the consideration of the centrifugal force field in the side-channel and in the impeller vane grooves. For the determination of performance curve (head-flow rate), momentum exchange theory is used. The effects of various geometric parameters and loss coefficients used in the performance prediction method on the head and efficiency are discussed, and the results were compared with experimental data.
소아 환자의 진정을 위한 chloral hydrate의 효과
최영석(Young Seok Choi),손영준(Young Joon Son),송은송(Eun Song Song),조영국(Eun Song Song),김영옥(Young Ok Kim),김찬종(Young Ok Kim, M),우영종(Young Jong Woo) 대한소아신경학회 2008 대한소아신경학회지 Vol.16 No.1
목 적 : 소아에게 검사나 시술을 하기 위해서는 진정이 필요하다. Chloral hydrate는 소아의 진정에 가장 많이 사용되는 약제이나 때로 그 진정효과가 나타나지 않는 경우를 볼 수 있다. Chloral hydrate의 진정 효과에 대한 보고는 많지 않아 이 에 chloral hydrate의 효과에 대하여 조사해 보고 소아에게 사용할 수 있는 효과적인 진정 방법을 찾아보고자 본 연구를 시행하였다. 방 법 : 2005년 1월부터 12월까지 전남대학교병원 소아과 입원 환아 중 chloral hydrate를 사용하였던 324명을 대상으로 하였다. 환아들의 나이, 성별, 체중, 진단명, 신경계 질환의 유무, 경련의 유무, 발달 지연의 유무, 시행한 검사, chloral hydrate의 용량, 초기 반응, 지연 반응 등을 조사하였다. 진정 효과는 투여 30분 후 Skeie scale 상 3점 미만인 경우 진정 실패로 간주하였다. 진정 효과가 없는 경우에는 midazolam, diazepam, ketamine 혹은 phenobarbital등을 단독 혹은 병용하여 추가로 사용하였고 이에 대한 반응을 조사하였다. 결 과 : 대상 환아의 연령은 평균 27개월(16일-14세 1개월) 이었다. 324명중 chloral hydrate에 의한 진정이 실패한 환아는 107명(33.0%) 이었다. 신경계 질환을 가지고 있는 환아 161명중 77명이 실패하여 47.8%에 해당되었다. 발달 지연, 경련, 발달 지연과 경련이 동시에 있는 경우의 진정 실패는 56.8%(25/44), 50.0%(58/116), 64.7%(22/34)이었다. Chloral hydrate에 반응하지 않아 midazolam 등의 추가 진정약물을 병용한 환아는 101명이었으며 그 중에서 14명(13.9%)이 진정에 실패하였다. 결 론 : 발달 지연, 경련 발작 등의 신경계 질환이 있는 환아에서는 chloral hydrate에 의한 진정이 힘들고 과도한 용량으로 인한 부작용을 보이기 쉬워 chloral hydrate 에 진정 작용을 보이지 않는 환아들에 있어서, 반복하여 동일 제제를 사용하기보다는 midazolam 등의 약제를 고려해 보아야 하며, 이들 약제에도 진정되지 않는 경우에는 다른 효과적인 방법이 연구되어야 할 것으로 사료된다. Propose : Sedation is often needed to perform an imaging study or procedure on a child. Although chloral hydrate is the most commonly used drug for pediatric sedation, little data are available for its efficacy or adverse effects. This study was undertaken to evaluate the efficacy of chloral hydrate for sedation and define any problems for using this agent in children. Methods : The medical records of 324 infants and children, who were admitted at Chonnam National University Hospital from January 2005 to December 2005 were retrospectively reviewed. Age, sex, body weight, underlying diagnosis, performed procedure, dose of chloral hydrate, initial response, delayed response and other additional agents for sedation were reviewed. If the desired level(3 on the Skeie scale) was not reached within 30 min after the administration of drugs, sedation was considered as potentially failed. Results : The average age of the study group was 27 months. Among 324 patients, 107 (33.0%) failed for chloral hydrate sedation. 77(47.8%) of the neurologically impaired 161 patients and 30(18.4%) of the unimpaired 163 patients failed on sedation with chloral hydrate. Among neurologically impaired cases, who had either developmental delay or seizures or both of them, 56.8%(25/44), 50.0%(58/116) and 64.7%(22/34) in each category respectively failed on sedation with chloral hydrate. Conculsion : In neurologically impaired patients, sedation by chloral hydrate was so difficult and prone to have adverse effects that it is recommended to supplement another drug than to administer the same drug again. However, further studies on effective methods of sedation are needed.