• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.11a
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• pp.82-90
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• 2000

Improving the atomization characteristics by adopting the Air-Shrouded injector has been considered as one of the important methods for decreasing HC emissions in SI engines. Thus, in this study for the purpose of developing Air-Shrouded injector which has a finer spray, atomization characteristics of different types of commercial Air-Shrouded injectors were investigated through the spray imaging and the drop size measurements. As a result, it was found that the internal mixing type of Air-shrouded injector had a good atomization characteristics. But, a number of large droplets were found in the internal mixing type commercial injector, this phenomenon was improved by adopting the thread type nozzle passages.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.793-808
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• 2009

This paper presents procedure and prediction method of internal and external stabilities when designing D.C.M, with main factors to be considered, such as chemical reaction of additive, physical properties of stabilized body and mixing strength. Results show that through case studies, a design unconfined compressive strength of stabilized body (hereafter referred to as 'compressive strength') directly depends on the quantity of cement, which is decided by laboratory test, and the compressive strength enormously affects internal and external stabilities. So laboratory mixing test to obtain the compressive strength for design allowable stress should be given careful considerations.

• Polymer Science and Technology
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• v.2 no.4
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• pp.250-256
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• 1991

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.157-165
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• 2017

The high-pressure resin transfer molding (HP-RTM) technology has been commercialized for fast production of fiber reinforced composite materials. The high-pressure mixing head was one of the most core component of the HP-RTM process. In this study, a mixing head was systematically designed, manufactured and evaluated. This mixing head was composed of a nozzle, a mixing chamber, a cleaning piston part, and an internal mold release part. In actual, a straight-type structure was newly designed instead of the conventional L-type structure for improving the maximum mixing pressure and mixing ratio precision. The performance of mixing head was showed maximum mixing pressure of 15.22MPa and mixing ratio precision of 0.12%. CFRP molding experiments were successfully obtained a 6~11 laminating carbon sheet using HP-RTM presses and specimen molds.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.5
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• pp.72-77
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• 2007

The combustion test results of the sub-scale combustor having dual swirl injector with internal mixing for a liquid rocket engine are described. The sub-scale combustor uses liquid oxygen(LOx) and kerosene as propellants and has an injector head, an ablative material combustor wall and a water cooled nozzle. The injector head has LOx manifold, fuel manifold, fire face plate, one center swirl injector and 18 main swirl injectors of internal mixing. The combustion tests were successfully performed at design and off-design points without any damages on the injectors. Combustion characteristics velocity of 1756m/s was measured at design point. High frequency combustion instability was not observed but low frequency pulsations occurred at off-design conditions.

• Korea-Australia Rheology Journal
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• v.18 no.3
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• pp.143-151
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• 2006

We analyzed the non-Newtonian and non-isothermal flow in a single screw extruder system and investigated the mixing performance with respect to the screw speed and the screw pitch. The viscosity of polymer melt was described with Carreau-Yasuda model. The mixing performance was computed numerically by tracking the motions of particles in the screw element system. The extent of mixing was characterized in terms of the deformation rate, the residence time distribution, and the strain. The results revealed that the high screw speed reduces the residence time but increases the deformation rate while the small screw pitch increases the residence time. It is concluded that the high screw speed increases the dispersive mixing performance and the small screw pitch increases the distributive mixing performance.

• Journal of ILASS-Korea
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• v.11 no.2
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• pp.59-68
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• 2006

Experimental results of the metal powder production with internal mixing, internal impinging and the atomizer coupled with substrate design are presented in this paper. In a test with internal mixing atomizer, mean powder size was decreased from $37{\mu}m\;to\;23{\mu}m$ for Pb65Sn35 alloy as the gas-to-melt mass ratio was increased from 0.04 to 0.17. The particle size further reduces to $16.01{\mu}m$ as the orifice area is increased to $24mm^2$. The micrograph of the metal powder indicates that very fine and spherical metal powder has been produced by this process. In a test program using the internal impinging atomizers, the mean particle size of the metal powder was decreased from $22{\mu}m\;to\;12{\mu}m$ as the gas-to-melt-mass ratio increased from 0.05 to 0.22. The test results of an atomizer coupled with a substrate indicates that the deposition rate of the molten spray on the substrate is controlled by the diameter of the substrate, the height of the substrate ring and the distance of the substrate from the outlet of the atomizer. This in rum determines the powder production rate of the spraying processes. Experimental results indicate that the deposition rate of the spray forming material decreases as the distance between the substrate and the atomizer increases. For example, the deposition rate decreases from 48% to 19% as the substrate is placed at a distance from 20cm to 40cm. On the other hand, the metal powder production rate and its particle size increases as the subsrate is placed far away from the atomizer. The production of metal powder with mean particle size as low as $3.13{\mu}m$ has been achieved, a level which is not achievable by the conventional gas atomization processes.

• Nuclear Engineering and Technology
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• v.38 no.8
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• pp.753-762
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• 2006

In this paper, works related to enhancement of the CHF are reviewed in terms of fundamental mechanisms and practical applications. Studies on CHF enhancement in forced convection are divided into two categories, CHF enhancement of internal flow in tubes and enhancement of CHF in the nuclear fuel bundle. Methods of enhancing the CHF of internal flows in tubes include enhancement of the swirl flow using twisted tapes, a helical coil, and a grooved surface; promotion of flow mixing using a hypervapotron; altering the characteristics of the heated surface using porous coatings and nano-fluids; and changing the surface tension of the fluid using additives such as surfactants. In the fuel bundle, mixing vanes or wire wrapped rods can be employed to enhance the CHF by changing the flow distributions. These methods can be applied to practical heat exchange systems such as nuclear reactors, fossil boilers, fusion reactors, etc.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.4
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• pp.43-52
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• 1994

I investigated experomentally the spray characteristics to the operating conditions and the shapes of internal mixing twin fluid atomizer. The wide variations of air per liquid ratio are conducted to predit the influences of the Sauter mean diameter(SMD), spray angle, distribution of drop size, the flowing condition of gas and length, flowing, area of gas and liquid, and diameter, number and place of the orifice. In this experiment, air per liquid raio, mixing chamber length per diameter, orifice diameter, and the flowing area ratio of gas and fluid influences greatly on SMD, spray angle, distribution of drop size and intermittent fluctuation region.

• Journal of Forest and Environmental Science
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• v.31 no.2
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• pp.119-125
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• 2015

This study examined the effects of rice straw steaming time and mixing ratio between rice straw and wood particle on the properties of mixed particle board from Acacia mangium Willd wood and rice straw. Rice straw and Acacia mangium Willd wood were collected in Hanoi, Vietnam. The particle board was three-layer particle board with the structural ratio of 1:3:1. The thickness, density and board size of the particle board were 18 mm, $0.7g/cm^3$, and $800{\times}800{\times}18$ (mm, including trimming), respectively. A resin mixture between commercial Urea-formaldehyde (U-F) adhesive and methylene diphenyl isocyanate (MDI) adhesive was used with a dosage of 12% for the core layer and 14% for the surface layer. In this experimental design, the steaming time for rice straw was 15, 30, 45, 60, and 75 minutes at $100^{\circ}C$. The rice straw-wood mixing ratio was 10, 20, 30, 40, and 50%. The results showed that both mixing ratio and steaming time affect the properties of the particleboard, but the mixing ratio has a stronger impact. A higher mixing ratio and a longer steaming time resulted in a better quality of particleboard. The optimal steaming time for rice straw was 46.12 minutes with the straw-wood mixing ratio of 29.85% with the following characteristics of the particle board: the modulus of rupture (MOR) of 14.64 MPa, internal bond strength (IB) of 0.382 MPa, thickness swelling (TS) of 8.83%, and board density of $0.7-0.7g/cm^3$.