• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.109-114
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• 2001

In this study, the physical and dynamic characteristics of Bottom-ash produced at steam power plants were compared and considered. The comparative objects were Bottom-ash in which a lot of powder contained and that in which less than that relatively contained. The difference in quantity of powder showed different effect on the character of flow. This study was undertaken on the use of Bottom-ash as a fine aggregate, and showed the durability and the character of strength according to each rate.

• Journal of Powder Materials
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• v.20 no.5
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• pp.382-387
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• 2013

• Journal of the Korean Ceramic Society
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• v.30 no.2
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• pp.131-138
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• 1993

The effects of silane coupling agents on the injection molding process were investigated using silicone nitride mixtrues with a binder system containing polypropylene as a major binder (55vol% solid loading). The formation of bonding between silicon nitride powder and coupling agents was confirmed through the analyses of powder surface. The use of coupling agents improved mixing characteristics judged by the torque change during mixing process. the coupling agents also reduced molten viscosity of the mixture considerably, which is a main factor to determine the flow of the mixture. However, the bonding between coupling agents and polymers had a negative effect on the debinding process by retarding the thermal decomposition.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.706-707
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• 2006

Premixes treated with a binder, such as in the FLOMET process, exhibit better flow, reduced dusting and segregation and improved productivity and part consistency compared to conventional premixes. The binder treatment is highly suitable for high performance P/M applications which often require premixes containing very fine alloying additives and excellent die filling characteristics. With this process, various binders and lubricants can be utilized in order to make premixes with unique properties. In this paper, the characteristics and performances of bonded premixes are reported.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.594-595
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• 2006

Porous bearings are lubricated the oil that is contained in porous metal. Then they are always used with no oil supply, because of that, widely used electric motors. But, if oil flow out less than the limit, troubles often happen. This report shows that attempt of estimating oil quantity in porous bearing by using calculation that based Reynols' equation and Darcy's law, aimed of developing long life bearing. And comparing with experimental and calculation result, we show possibility of estimating rest oil quantity in porous bearing at steadry state by calculation.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.10-11
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• 2006

The use of hot gas in melt atomization has been widely reported, but little detailed experimental data on its precise effects and no satisfactory theory to explain them have been published. In this paper the authors present experimental data on the atomization of metals with gas at temperatures from ambient to 1000C, a semi-empirical equation relating particle size to gas temperature and flow rate, and an analysis of the gas dynamics of the atomization process that allows some insight into the process.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.05a
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• pp.153-158
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• 2000

Flow visualization and PIV measurements were conducted to investigate the flow characteristics of multi-channel with inclination angle. The water flow seeded with tiny vegetable powder as tracers revealed details of flow field. The PIV measurement to acquire multi-point velocity data simulatneously was carried out at three space of plates for 5, 10, and 15mm with variation of inlet flow rates of $0.25m^3/h$ and <$0.5m^3/h.$ Experiment results show that space of plates acts a significant role in separating process.

• Korean Chemical Engineering Research
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• v.53 no.5
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• pp.597-602
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• 2015

Characteristics of continuous preparation of ZnO powder were investigated in a micro drop/bubble fluidized reactor of which diameter and height were 0.03 m and 1.5 m, respectively. The flow rate of carrier gas for transportation of precursors to the reactor was 6.0 L/min and the concentration of Zn ion in the precursor solutions was 0.4 mol/L, respectively. Effects of reaction temperature (973 K~1,273 K) and flow rate of micro bubbles (0~0.4 L/min) on the pore characteristics of prepared ZnO powder were examined. The optimum reaction temperature for the maximum porosity in the ZnO powder was 1,073 K within this experimental condition. The mean size of ZnO powder prepared continuously in the reactor decreased but the surface of the powder became smooth, with increasing reaction temperature. The injection of micro bubbles into the reactor could enhance the formation of pores in the powder effectively, and thus the mean BET surface area could be increased by up to 58%. The mean size of prepared ZnO powder was in the range of $1.25{\sim}1.75{\mu}m$ depending on the reaction temperature.

• Journal of Powder Materials
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• v.11 no.1
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• pp.50-54
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• 2004

Nanoparticles of iron oxides have been prepared by the levitational gas condensation (LGC) method, and their structural and magnetic properties were studied by XRD, TEM and Mossbauer spectroscopy. Fe clusters were evaporated from a surface of the levitated liquid Fe droplet and then condensed into nanoparticles of iron oxide with particle size of 14 to 30 nm in a chamber filled with mixtures of Ar and $O_2$ gases. It was found that the phase transition from both $\gamma$-$Fe_2O_3$ and $\alpha$-Fe to $Fe_3O_4$, which was evaluated from the results of Mossbauer spectra, strongly depended on the $O_2$ flow rate. As a result, $\gamma$-$Fe_2O_3$ was synthesized under the $O_2$ flow rate of 0.1$\leq$$Vo_2$(Vmin)$\leq$0.15, whereas $Fe_3O_4$ was synthesized under the $O_2$, flow rate of 0.15$\leq$$Vo_2$(Vmin)$\leq$0.2.

• Korean Journal of Materials Research
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• v.27 no.2
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• pp.119-126
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• 2017

WC-CrC-Ni coatings were prepared by nine processes of the Taguchi program with three levels for the four spray parameters: spray distance, flow rates of hydrogen and oxygen, and powder feed rate. The optimal coating process (OCP) was oxygen flow rate of 38 FMR, hydrogen flow rate of 53 FMR, powder feed rate of 25 g/min, and spray distance of 7 inches. Hardness of 1150 Hv and porosity of 1.2 %, were obtained by OCP; these are better results compared with the highest 1033 Hv and the lowest 1.5 % porosity obtained by nine processes of the Taguchi program. Friction coefficient of the WC-CrC-Ni coating decreased from $0.36{\pm}0.07$ at $25^{\circ}C$ to $0.23{\pm}0.07$ at $450^{\circ}C$. These values were smaller than those of the EHC (electrolytic hard chrome) plating at both temperatures due to lubrication from the oxide debris. The wear trace and wear depth of the coating are smaller than those of the EHC at both temperatures. Pitting was not found in the WC-CrC-Ni coating sample, while it did appear in the EHC sample.