• 대한간호학회지
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• 제44권2호
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• pp.149-158
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• 2014

Purpose: This study was conducted to compare effects of open and closed suctioning methods on lung dynamics (dynamic compliance, tidal volume, and airway resistance) and hypoxemia (oxygen saturation and heart rate) in mechanically ventilated patients. Methods: This study was a cross-over repeated design. Participants were 21 adult patients being treated with endotracheal intubation using a pressure-controlled ventilator below Fraction of Inspired Oxygen ($FiO_2$) 60% and PEEP $8cmH_2O$. Data were collected at baseline and 1, 2, 3, 4, 5, and 10 minutes after suctioning. Data were analyzed using two-factor ANOVA with repeated measures on time and suctioning type. Results: Effects of the interaction between suction type and time were significant for oxygen saturation and heart rate but not significant for dynamic compliance, tidal volume, or airway resistance. Prior to performance of suctioning, tidal volume and oxygen saturation were significantly lower, but airway pressure and heart rate were significantly higher using the closed suctioning method as compared with the open suctioning method. Conclusion: For patients on ventilator therapy below $FiO_2$ 60% and PEEP $8cmH_2O$, open suctioning performed after delivery of 100% $FiO_2$ using a mechanical ventilator may not have as much negative impact on lung dynamics and hypoxemia as closed suctioning.

• Journal of Advanced Marine Engineering and Technology
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• 제18권1호
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• pp.51-59
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• 1994

The gas jet pumps serve to preduce a vacuum or can be used as gas jet compressors. These are operated on the same principle as a steam jet vacuum pump : in the driving nozzle the pressure energy of the motive medium is converted into the kinetic energy. In the diffuser the driving jet mixes with the suction medium and the kinetic energy is reconverted into the pressure enegy. The application fields of gas jet ejectors are the evacuation of siphoning installations, the elevation of liquids, the production of vacuum filters, the vacuum supporting airlift system, the evacuation of the suction line of centrifugal pumps and the ventilation of the dangerous gases to the atmosphere. The performance of gas jet ejector is influenced strongly to velocity coefficient of motive nozzle, the distance between the motive outlet to the diffuser inlet and the dimensions of diffuser. This study is performed for the computer aided design of gas jet ejectors in future. Through the present experiments, it is known that the velocity coefficient of the motive air nozzle ranges from 0.91 to 0.95 and the maximum efficiency of gas jet ejector is 24.6%.

• 한국항공우주학회지
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• 제39권8호
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• pp.735-743
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• 2011

본 연구에서는 직선형 터빈 캐스케이드 장치를 이용하여 분사영역으로 진입하고 퇴각하는 익형의 허브, 평균반경, 팁에 형성되는 표면에서의 압력을 정상상태에서 측정하였다. 익형은 축류형으로 코드가 200mm이며, 분사 노즐은 단면은 사각형으로 그 크기는 $200mm{\times}200mm$이다. 실험은 코드 기준으로 레이놀즈수 $3{\times}10^5$에서 수행되었다. 탈설계 성능을 측정하기 위하여 노즐의 설치각을 $58^{\circ}$, $65^{\circ}$와 $72^{\circ}$로 변경하면서, 노즐의 설치각 변화에 대한 익형에서 표면압 변화의 특성을 파악하였다. 또한 현절비를 1.25, 1.38, 1.67로 변경하면서 현절비 변화에 대한 익형의 표면압 변화를 측정하였다. 실험의 결과에서 익형이 분사영역으로 진입할 때 현절비가 적을수록 흡입면에서는 표면압력의 감소가 발생되었고 낮은 노즐설치각인 경우에는 역회전방향의 힘이 형성되었다. 아울러 양의 입사각으로 익형이 분사영역으로 진입할 때 흡입면의 앞부분에 낮은 압력이 형성되었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1371-1376
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• 2004

Flow analysis of automobile front-end cooling fan are numerically investigated. The Navier-Stokes equations and the continuity equation are solved in the flow domain. The Reynolds stresses are modelled using the $k-{\varepsilon}$ turbulence model. Flow and pressure characteristics around the fan are investigated. The pressure sharply increases through the fan. Pressure variations on the pressure and suction sides of the fan are well represented in the calculations. The flow streamlines in the blade passage are nearly parallel to the blade.

• 한국유체기계학회 논문집
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• 제8권6호
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• pp.33-39
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• 2005

A thermal vapor compressor in which the subsonic/supersonic flow appears simultaneously, has been accurately designed through the CFD analysis for the various shape parameters such as the primary nozzle shape, converging duct shape, mixing tube diameter, and so on. The performance of the developed thermal vapor compressor has been experimentally verified to be installed in a Multi Effect Desalination(MED) plant as an important element. In this paper, the effects of each parameter are discussed on the basis of CFD results and the experimental results for various boundary conditions(motive pressure, suction pressure, and discharge pressure) are presented in compared with CFD results. The two results show a good agreement with each other within 2 % accuracy with regard to the entrainment ratio.

• International Journal of Fluid Machinery and Systems
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• 제9권1호
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• pp.95-106
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• 2016

A method of optimization design for the blade profile of a centrifugal impeller by controlling velocity distribution is presented, and a plenum fan is successfully designed. This method is based on the inner flow calculation inside the centrifugal impeller, and is related to the distribution of relative velocity. The results show that after optimization, the boundary layer separation on the suction surface has been inhibited and the stability of plenum fan is improved. The flow at the impeller outlet is also studied, and the jet-wake pattern at the impeller outlet is improved obviously by optimization. The calculation result shows that the static pressure and static pressure efficiency can be increased by 15.4% and 21.4% respectively.

• 설비공학논문집
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• 제12권10호
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• pp.901-907
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• 2000

The conceptual determination of mixed-refrigerant (MR) for a closed Joule-Thomson cryocooler is described in this paper. The thermodynamic cycle design was mainly considered to develop a cryocooler by using a compressor of domestic air-conditioning unit. The target cooling performance of the designed cryocooler is 10 W around 70 K with less than 5 kJ/kg enthalpy rise. The systematic approach of choosing a proper refrigerant among 20 different kinds of mixture for such cryogenic temperature was introduced in detail. The main components of the cryocooler are compressor, evaporator, oil separator, after-cooler, counterflow heat exchanger, and J-T expansion device. Due to the limitation of the compressor operation range, the temperature after the compression was limited below $117^{\circ}C$ (390 K) and the temperature before compression was restricted above $5^{\circ}C$ (278 K). 20 atm of discharging pressure (high pressure) and less than 3 atm suction pressure (low pressure) were the design conditions. The inlet temperature of a counterflow heat exchanger in the high Pressure side was about 300 K. The proper composition of the mixed refrigerant for the designed J-T cryocooler is 15% mol of$ N_2, 30% mol of $CH_4,\; 30% mol\; of C^2H^ 6,\; 10%\; mol\; of\; C_3H_8\; and \;15%\; mol\; of\; i-C_4H_10$.

• 한국지반공학회논문집
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• 제26권11호
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• pp.75-87
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• 2010

불포화토에 강우가 지속되면 토체내 간극수압이 상승하게 된다. 따라서 토층의 포화로 인해 강도가 저하되고, Suction압이 균형을 이루는 임계 깊이까지 Wetting Front가 하강하여 사면붕괴가 발생한다. 지중 간극수압을 제어할 수 있다면 강도저감을 방지함으로써 사면안정을 유지할 수 있을 것이다. 본고는 지중 간극수를 흡수하여 배출할 수 있는 흡수관 설계를 시도하여 실험성과로 그 가능성을 제시하였다. 흡수관은 사면안정을 위한 보조공법으로 활용하는 것이 효과적일 것이다.

• 한국정밀공학회지
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• 제20권6호
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• pp.167-177
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• 2003

In this study, a mathematical nonlinear dynamic model is introduced to predict the damping force of automotive shock absorber. And 11 design parameters were proposed for the sensitivity analysis of damping force. Design parameters consist of 5 piston valve design parameters, 5 body valve design parameters and 1 initial pressure of reservoir chamber air. All of these design parameters are main design parameters of shock absorber in the procedure of shock absorber design. The simulation results of this paper offer qualitative information of damping force variation according to variation of design parameters. Therefore, simulation results of this paper can be usefully use in the design procedure of shock absorber

• Journal of Advanced Marine Engineering and Technology
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• 제39권4호
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• pp.456-462
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• 2015

본 연구는 토네이도와 축류펌프의 원리를 적용하여 마중물 없이 슬러리를 송출할 수 있는 새로운 펌프기술 개발을 목적으로 한다. 개발한 로터형 슬러리 펌프는 전동모터, 구동축 및 커플링, 로터, 임펠러 그리고 흡입 및 송출관으로 구성된다. 청수를 이용한 성능실험에서는 로터의 설계조건에 따른 송출량, 소비 전력량 그리고 흡입관 부압특성에 대해 모터의 회전수를 변수로 검증하였으며, 시멘트를 이용하여 제조한 슬러리의 고형물 농도에 따른 송출량 특성에 대한 검증연구를 수행하였다. 로터의 직경과 높이가 커지면 송출량과 소비되는 전력량은 증가하지만 흡입관 부압은 감소하였으며, 송출량과 부압에 미치는 로터 두께의 영향은 거의 나타나지 않았다. 개발지표로 제시하였던 18 % 이상의 고형물 농도에서도 슬러리의 송출이 가능함을 확인하였다.