• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.46 no.6
• /
• pp.496-502
• /
• 2018

In this study, experimental and analytical studies were carried out to observe the phenomenon of aerodynamic throat formed according to the primary flow and secondary flow momentum of the ejector. The equilibrium interval of the aerodynamic throat, which is the main variable of the ejector performance, was observed through the experiment using the cold flow experiment and the analysis using FLUENT. Performance characteristics were investigated by the change of the primary flow rate and the throat diameter of the ejector cylinder. As a result, the performance of the standard ejector was confirmed to be within the range of 0.33~1.167(off-design/design) and cylinder throat diameter range of 1~1.17(off-design/design area ratio).

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.05a
• /
• pp.275-278
• /
• 2010

By changing the nozzle throat area during the operation, thrust of a pintle thruster can be adjusted easily such as a liquid propulsion. In this paper, numerical analysis was carried out for SNECMA's pintle thruster with different pintle shapes. Flow field and aerodynamic load changed drastically with pintle shapes. Bore in the pintle decreased aerodynamic load significantly.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.29 no.12 s.243
• /
• pp.1285-1290
• /
• 2005

A theoretical analysis of an annular injection supersonic ejector equipped with a second-throat was developed under the assumption that the secondary flow is choked aerodynamically by interaction with primary flow in the mixing chamber. The predicted secondary flow pressure agrees reasonably well with the measurements. Using the analysis, the compression ratio, the secondary flow Mach number, and the location of the choking point were presented in terms of entrainment ratio.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
• /
• v.13 no.1
• /
• pp.117-128
• /
• 2002

Objectives：For the purpose of obtaining the more vivid present status and prevention program of teenage pregnancy, this survey was done by Obstetricians, as study subject, who manage the pregnant teenager in real clinical situation. Methods：Structured survey form about teenage pregnancy was sent to 2,800 obstetricians. That form contained frequency, characteristics, decision making processes, and psychiatric aspects of the teenage pregnancy. 349 obstetricians replied that survey form and we analysed these datas. Results：(1) The trend of teenage pregnancy was mildly increased. (2) The most common cases were unwanted pregnancy by continuing sexual relationship with boyfriends rather than by forced, accidental sexual relationship with multiple partners. (3) The most common reason of labor was loss the time of artificial abotion. (4) Problems of pregnant girls' were conduct behaviors and poor informations about contraception rather than sexual abuse or mental retardation. (5) Most obstetricians percepted the necessity of psychiatric consultation, however psychiatric consultation was rare due to parents refusal and abscense of available psychiatric facility. (6) For the prevention of teenage pregnancy, the most important thing was practical education about contraception. Conclusions：Based on the result of this study, further study using structured interview schedule with pregnant girl is needed for the detecting risk factor of teenage pregnancy and effective systematic approach to pregnant girl.