• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2009.05a
• /
• pp.141-144
• /
• 2009

An injector plays an important role in the process of an efficient combustion in liquid-rocket engines (LRE). This paper is focused on the injection performance of a small LRE-injector by employing the spray characteristic parameters made up of the velocity, Sauter mean diameter, and turbulence intensity. An experimental investigation is carried out with the aid of a dual-mode phase Doppler anemometry (DPDA) according to the injection pressure variation and along transverse axis, spatially. The Weber number and Reynolds number are used to characterize the atomization and turbulence nature of injector spray.

• Journal of Power System Engineering
• /
• v.17 no.2
• /
• pp.38-45
• /
• 2013

In this study, for carrying out the spray and combustion experiment using a Common Rail Direct Injection(CRDI) system, the controller was fabricated to drive a high speed camera, a injector and a laser beam sequentially at a low cost. CB280 module of one-chip micro processer was used for the controller. In order to confirm responsibility and utility of the controller, the current drive performance, the spray behavior and the injection rate were tested and analyzed under various experimental conditions. As this research results, we found that the fabricated controller was able to control the devices for the spray experiment precisely with the input value in program and it had the dynamic load responsibility and repetition. Also, we found that the injection rates of our experimental results were higher than those of others at the same injection pressure and the controller connected with the laser system and the data acquisition system had validity for carrying out the spray visualization experiment.

• The Journal of Korean Academic Society of Nursing Education
• /
• v.17 no.1
• /
• pp.25-35
• /
• 2011

Purpose: The purpose of this study was to evaluate the effects of an intravenous injection case-based clinical performance examination for improvement of problem-solving skill, nursing process application, nursing skill, and learning satisfaction. Method: This study's design was a randomized control group design. A total 93 students (experimental group, 49 control group, 44) who were junior nursing students in South Korea were included in this study. Data were collected from August 12th to 19th, 2010 and analyzed using SPSS 18.0. Result: The mean score of problem solving skills, intravenous injection skill, and learning satisfaction were significantly higher in the experimental group than the control group. However, the mean score of nursing process application was not significantly different between the two groups. Conclusion: These results indicate that the case-based clinical performance examination is effective for problem solving skill, nursing skill, and learning satisfaction. Therefore, it is recommended to adapt such teaching methods with integrated nursing practice education for various clinical skills development.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2010.11a
• /
• pp.423-431
• /
• 2010

In order to investigate the effect of fuel injection hole configuration within the scramjet combustor, experiment and quasi-one-dimensional analysis was performed. And the results were compared with experiment and analysis result which were performed in 2008 with same facility and test condition. Fuel injection hole size was decreased and quantity was increased. However the depth of fuel penetration and fuel flow were maintained. As a test result, combustion performance was increased significantly with no-cavity injector and slightly with plain-cavity. However, combustion performance with zigzag-cavity was decreased.

• Transactions on Electrical and Electronic Materials
• /
• v.18 no.2
• /
• pp.89-92
• /
• 2017

The performance of three-layered organic light-emitting diodes (OLEDs) was investigated using TPD hole-transport and injection layers, Teflon-AF, and the electron-injection layer of $Li_2CO_3$ and LiF. The OLEDs were manufactured in a structure of TPD/$Alq_3$/LiF, TPD/$Alq_3$/$Li_2CO_3$, and AF/$Alq_3$/LiF using low-molecular organic materials. In three different three-layered OLEDs, it was found that the device with the TPD/$Alq_3$/LiF structure shows higher performance in maximum luminance, and maximum external quantum efficiency compared to those of the device with TPD/$Alq_3$/$Li_2CO_3$ and TPD/$Alq_3$/LiF by 35% and 17%, and 193% and 133%, respectively. It is thought that the combined LiF/Al cathode contributes to a reduced work function and improves an electrical conduction mechanism due to the electron injection rather than the hole transport, which then increases a recombination rate of charge carriers.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.3
• /
• pp.604-610
• /
• 2007

Injection molding is the most common method of shaping plastic resins for manufacturing a variety of parts. This injection molding is accomplished by injection molding machines (IMM) which consists of a hewer, a reciprocating screw, barrel assembly, and an injection nozzle. The plastic resin is fed to the machine through the hopper and it should be heated to the target melting temperature, which depends on material properties, as closely as possible with very small temperature overshoot in the barrel. Since the barrel, which has temperature dependent specific heat and thermal conductivity in the operating temperature range, is heated by the several electric heater bands, it is not an easy task to control the temperature of the barrel owing to the interference of neighboring heaters and its material properties. Though PID controller with auto-tuning capability is widely adopted in the nm, the auto-tuning process should be carried out whenever the operating temperature is changed significantly. Recently, though the predictive controller is developed and shows good performance, it has drawbacks: 1. Since the heat transfer modeling process is very complicated and should be carried out again when the barrel is changed, it is somewhat inappropriate in the field. 2. The controller performance is not validated in whole operating temperature range. In this paper, cascade type simple PI controller with input restriction is proposed to find the possibility of controlling the barrel temperature in the whole operating temperature range. It is shown by experiment that the proposed controller shows good performance. This result can be applied to design of PI controller with auto-tuning capability.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.5 no.1
• /
• pp.18-25
• /
• 2001

The results of systematic numerical experiments of secondary gas injection thrust vector control are presented. The effects of secondary injection system such as injection location and nozzle divergent cone angle onto the overall performance parameters such as thrust ratio, specific impulse ratio and axial thrust augmentation, are investigated. Complex nozzle exhaust flows induced by the secondary jet penetration is numerically analyzed by solving unsteady three-dimensional Reynolds-averaged Navier-Stokes equations with Baldwin-Lomax turbulence model for closure. Numerical simulations compared with the experiments of secondary air injection into the rocket nozzle of $9.6^{\cire}$ divergent half angle showed good agreement. The results obtained in terms of overall performance parameters showed that locating the secondary injection orifice further downstream of primary nozzle ensures the prevention of occurrence of reflected shock wave, therefore is suitable for efficient and stable thrust vectoring over a wide range of use.

• Design & Manufacturing
• /
• v.13 no.1
• /
• pp.61-67
• /
• 2019

The cooling unit of the industrial showcase consists of a compressor, a condenser and an evaporator. An axial fan is used to circulate the air to improve the efficiency of the heat exchanger. In the past, aluminum fans have been used, which have problems such as low performance, efficiency, high failure rate, and high noise. This study is to develop high performance, high efficiency plastic fan replacing aluminum fan. A major factor in determining the performance and noise of an axial fan is the angle and cross-sectional shape of the blade, which is suitable for raising the lift force, thereby controlling the vortex, which is the main cause of noise and performance degradation. In order to produce a high efficiency injection molded fan, it is necessary to develop a mold that minimizes the deformation of the injection process for the designed shape. In this study, we developed a high efficiency, low noise plastic injection fan with more than 11% performance improvement and noise reduction compared to conventional aluminum fan.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• v.y2005m4
• /
• pp.215-218
• /
• 2005

An optimal fuel manifold is suggested to improve the cooling performance of injector face plate. The cooling performance at the center area of the injector face plate is to be augmented while the spatial injection uniformity is maintained. The comparison of the cooling performance of 7 candidates gives the conclusion that the dividing plate from 2-3 injector row to 9-10 injector row is an optimal. The maximum face plate temperature decreases by $27\%$ while the injection uniformity is close to that of the original design. The pressure drop in the fuel manifold of the optimal design is also same as the original design.

• Asian-Australasian Journal of Animal Sciences
• /
• v.20 no.10
• /
• pp.1600-1605
• /
• 2007

This study was undertaken to investigate the effects of oxidative stress on growth performance, nutrient digestibilities and activities of antioxidant enzymes of weanling pigs. In the experiment, 24 male $Landrance{\times}Yorkshire $weanling pigs were allotted to three groups of 8 animals each. Pigs were fed individually. According to a single factorial arrangement, pigs received diets with 5% of either fresh (group 1 and group 3) or oxidized fish oil (peroxide value was 786.50 meq $O_2/kg$ before inclusion in the diet, group 2). At the beginning of the experiment, pigs in group 3 received an intraperitoneal injection of diquat at 12 mg/kg of body weight. The trial lasted for 26 d. A metabolism test was carried out during the last 4 days of the second week. The results showed that feeding diets containing oxidized fish oil or injection with diquat depressed the growth performance and nutrient digestibilities of weanling pigs, decreased activities of antioxidant enzymes and increased concentration of malondialdehyde in plasma and liver. Intraperitoneal injection of diquat would induce more serious oxidative stress than oral intake of oxidized fish oil in the diet. In conclusion, administration of oxidized fish oil or diquat could induce oxidative stress in weanling pigs, and oxidative stress could depress growth performance and impact anti-oxidative ability of young pigs.