• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1738-1743
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• 2004

Turbo-pump system, an essential component of liquid rockets and induced weapons, adopts a partial admission axial turbine which drives pump. And the turbine of a turbo-pump system is usually operated at supersonic condition due to its high loading chracteristics. Therefore, reseaches about flow and performance characteristics of a partial admission supersonic turbine must be preceeded to progress the aerospace and defense industries as well as the development of turbo-pump systems. In this study, flow characterisitics within blades of the partial admission supersonic turbine are numerically investigated by using Fine Turbo, a commercial CFD Code. Before performing the numercial analyses, to verify accuracy of the numerical result computed by Fine Turbo, I performed the comparison between the numerical results with J.J.Cho' experimental results. It is found that the numerical results show good agreement with the experimental results. Computations about the partial admission supersonic turbine have been performed to investigate flow characteristics including shock patterns. It is also found that the flow and performance of partial admission supersonic turbine are largely depend on shocks ocurred in the nozzle and at the leading edge of blades, expansion or compression at exit of nozzle and separations occurred in passage.

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

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.153-162
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• 2005

Through a preliminary design process, four design candidates for a 1.4MW class partial admission turbine have been chosen and the numerical analyses using a frozen rotor method are applied to estimate their performance. Each flow analysis result was compared with others and the optimum design was selected. Flow characteristics in the passages and some types of losses induced by shocks and wakes were found from calculation results. A new rotor blade was redesigned based on these calculations and this result is compared with previous one through flow analysis.

• 월간산업보건
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• s.328
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• pp.55-59
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• 2015

톨루엔-2,4-디이소시아네이트, 톨루엔-2,6-디이소시아네이트 각각 또는 두 이성체 혼합물(TDI)에 대하여 TLV-TWA는 0.005 ppm, TLV-STEL은 0.02 ppm으로 직업적 노출기준을 권고하고 있다. 본 수치는 호흡기에 대한 영향과 과민성 반응에 대한 높은 발생 가능성을 최소화하기 위한 것이다. 산업현장에서 증기상 TDI 물질은 점막, 호흡기계에 심한 자극을 일으켜 천식과 같은 증후군 등 급성 발작을 유발한다. 고농도에 노출시 심한 기관지 경련, 폐렴, 폐부종, 두통, 불면증과 기관지염으로 이어질 수 있다. TDI에 상당 부분 노출되면 대부분의 사람들은 위와 같은 건강 영향을 경험하게 된다. 심지어 처음 노출되었을 경우에도 발생된다. TDI 노출 관련 연구자들은 일반 근로자들이 0.02 ppm 수준 정도로 가끔 노출되는 경우 건강 영향을 받지 않으나, 0.02 ppm이 무영향 수준으로 간주될 수 있는 그 어떠한 증거도 없다고 결론을 내렸다. TDI에 일단 감작되면 몇몇 근로자들은 노출 중단 후에도 몇 년 동안 건강 영향 증세가 지속된다. 따라서 감작제 표기는 호흡 노출을 통한 알레르기성 감작 증세의 명확한 증거로서 권고된다. A4(비발암성 물질) 표기는 생쥐와 흰쥐들을 대상으로 수행된 위장관 투여 연구와 흡입 연구들을 통해 얻어진 동물 노출 데이터에 근거하여 설정되었다. 불충분한 데이터로 피부 표기는 권고되지 않았다.

• The KSFM Journal of Fluid Machinery
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• v.10 no.1 s.40
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• pp.26-33
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• 2007

Four design candidates for a partial admission turbine have been chosen from a preliminary design process. Their performance were estimated through the 3-D numerical analyses using a frozen rotor method. In order to select the optimum design, each flow analysis result was compared with others. Flow characteristics in the passages and some types of losses induced by shocks and wakes were found from calculation results. Based on these calculations, a new rotor blade was redesigned and compared with previous one through flow analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.04a
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• pp.298-304
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• 1995

유동이 있는 경우 발생하는 소음에 대한 실험적 연구는 풍동과 무향실이 결합된 음향풍동에서 수행될 수 있다. 이러한 음향풍동은 팬, 수축부, 수집부, 확산부 그리고 무향실에 주의해서 설계되어야 하고 특히 각 부분에서 발생할 수 있는 이차소음을 최소화하도록 설계되어야 한다. 최종적으로 소음기와 흡음재를 이용해서 팬소음과 이차소음의 전파를 줄인다. 본 음향풍동은 개방형 흡입식(open suction type)으로 시험부에서 유속 62.8m/s, 난류강도 0.1%이하, 배경소음 50-55dB 이하로 설계되었다. 이러한 조건을 만족시키기 위하여 하니콤과 6장의 스크린이 있는 정체실과, 21:1의 수축비를 갖는 수축부를 이용하여 난류강도를 낮추고, 흡음재와 90도 각도의 모서리 그리고 공명형과 소산형 소음기로 소음의 전파를 줄였다.

• 한국전산유체공학회:학술대회논문집
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• 2005.04a
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• pp.191-196
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• 2005

For the improvement of aerodynamic performance of the turbine blade in a turbopump for the liquid rocket engine, the optimization of turbine profile shape has been studied. The turbine in a turbopump in this study is a partial admission of impulse type, which has twelve nozzles and supersonic inflow. Due to the separated nozzles and supersonic expansion, the flow field becomes complicates and shows oblique shocks and flow separation. To increase the blade power, redesign of the blade shape using CFD and optimization method was attempted. The turbine cascade shape was represented by four design parameters. For optimization, genetic algorithm based upon non-gradient search has been selected as a optimizer. As a result, the final blade has about 4 percent more blade power than the initial shape.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.261-262
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• 2000

항공기나 발전용 가스터빈(gas turbine) 및 대용량 압축기(compressor) 등과 같이 흡입공기의 유량이 매우 클 경우, 유입되는 공기 내부에 함유된 입자상 오염물질은 터빈의 기계적 성능에 큰 장애를 일으킬 수 있다(Klink and Schroth, 1996, Schroth, 1993). 이러한 입자상 오염물질을 효과적으로 제어하기 위해서는 처리기체의 유입구 부분에 대형 공기 정화용 여과시스템이 요구되며, 일반적으로 카트리지형 에어 필터(cartridge air filter)나 포켓형(pocket), 카세트형(cassette) 에어 필터가 적용 현장의 조건에 따라 사용된다. (중략)

• Journal of computational fluids engineering
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• v.10 no.2
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• pp.54-59
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• 2005

For the improvement of aerodynamic performance of the turbine blade in a turbopump for the liquid rocket engine, the optimization of turbine profile shape has been studied. The turbine in a turbopump in this study is a partial admission of impulse type, which has twelve nozzles and supersonic inflow. Due to the separated nozzles and supersonic expansion, the flow field becomes complicate and shows oblique shocks and flow separation. To increase the blade power, redesign ol the blade shape using CFD and optimization methods was attempted. The turbine cascade shape was represented by four design parameters. For optimization, a genetic algorithm based upon non-gradient search hue been selected as an optimizer. As a result, the final blade has about 4 percent more blade power than the initial shape.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.481-487
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• 2005

A turbopump turbine consists of rotational part including a rotor and stationary part including nozzles and exit guide vanes, of which shape and relative position affect turbine performance owing to supersonic flows with prevailing unsteadiness. In this study, numerical 3-D flow calculations of the turbine with the different number of exit guide vanes and different relative position of each component are conducted and the effect of flow passage variations on turbine performance is analyzed.