Papers by Author: Soo Ryong Kim

Abstract: AlN powders by the chemical vapor synthesis (CVS) process in the AlCl3-NH3-N2-H2 system were successfully synthesized. Gasified AlCl3 as a starting material was generated by pre-heating system and transported to the tube furnace in NH3-N2-H2 atmosphere. High crystalline AlN was synthesized at over 900°C. The average particle size of spherical AlN powders decreased from 250 to 40nm with increasing the reaction temperature of the tube furnace. Porous nano-size particles synthesized at high reaction temperature have low oxygen contents.

Abstract: In this work, the physical & chemical properties of bottom ash generated from power plant are analyzed. Characteristic mortar property and thermal conductivity for building material were investigated with content of added bottom ash. According to the analytic result of bottom ash, chemical compositions of bottom ash is similar to those of fly ash and compressive strength after 7days related to pozzolanic activity shows 2.5N/cm2 and it is confirmed that bottom ash possess a certain amount of moisture activity. Although the fluidity of cement mortar is rapidly decreased with increasing addition of bottom ash, compressive strength for 3 and 7days is increased. The thermal conductivity is not sensitive to the addition of bottom ash.

Abstract: The effects of the pair-minerializer (CaSO4,-CaF2) on the burnability of clinker and the formation of mineral are investigated. As experimental results, the addition of F as pair-mineralizer, the burnability of clinker was improved. Especially, the addition of F and SO3 components simultaneously as pair-mineralizer, total amount of free lime in clinker is rapidly decreased compared with the value which mineralizer was added separately. In case of adding K2O only to the raw mixes, the amount of free lime is increased. However, if alkali (K2O) and pair-minerializer (CaSO4,-CaF2) were added simultaneously, the produced amount of clinker mineral is increased due to the formation of stable calcium langbeinite by the combination of alkali (K2O) and sulfate

Abstract: A porous silicon-containing hydroxyapatite has been prepared using natural coral as a calcium source to obtain a biomaterial having an improved biocompatibility. From the XRD analysis, it was confirmed that the single-phase hydroxyapatite containing silicon has formed without revealing the presence of extra phases related to silicon dioxide or other calcium phosphate species. Silicon content is ranged from 0.5wt% to 1wt% by weight. The porous silicon-containing hydroxyapatite blocks were inserted into the 5mm diameter of drill holes made through the lateral femoral condyles of New Zealand white rabbits. The new bony formation did not begin after 1 week. At 3 week, bony ongrowth to the inserted porous silicon-containing hydroxyapatite block could be found, and the new bone surrounded the inserted block entirely after 24weeks. Based on in-vivo test, Si-containing porous hydroxyapatite derived from coral possesses high biodegradability and can be considered a useful material for bone implants.

Abstract: Ceramic membranes having less than 1nm size pores have great potential for gas separation at high temperature due to their good thermal stability. Moreover, nanoporous silicon carbide membrane has potential application under hydrothermal condition at high temperature since it is highly stable at high temperature. In this research, nanoporous SiC membrane has been developed on porous alumina support using preceramic polymer. Pore size of the SiC membrane was controlled using polystylene(PS) as the pore forming agent. The SiC membrane having controlled pore size was characterized with SEM, EDS, FT-IR, XRD and pore size measurement. The hydrogen permeability and selectivity toward nitrogen gas of the developed membrane were 0.3 x 10-6 mole/m2.s.pa and 4.1, respectively. The nanoporous hydrogen selective SiC membrane shows promising application in membrane reactor for steam reforming reacti on of natural gas, water gas shift reactions and hydrogen separation from coal gasification such as Integrated Gasification Combined Cycle (IGCC).

Abstract: Due to the need for CO2 sequestration associated with H2 production from fossil fuels, zeolite membrane are very promising due to their low cost, high stability and high permeance. Recently, the faujasite(FAU), the silica/aluminophophate(SAPO-4) framework family of zeolite have been studied for CO2 gas separation. In our study, ZSM-5 membrane was prepared on the porous alumina support using a hydrothermal technique. The thickness of zeolite membrane was controlled by the hydrothermal reaction time and temperature. The prepared zeolite membranes were characterized with SEM and thin film XRD. The hydrogen permeability and selectivity toward carbon dioxide gas were 0.6x 10-6 mole/m2.s.pa and 3.16, respectively. The hydrogen selective zeolite membranes show promising application in hydrogen separation from coal gasification such as Integrated Gasification Combined Cycle (IGCC).

Abstract: Rod shaped nanocrystalline powders of hydroxyapatite (HAp) were synthesized by a low temperature chemical route involving calcium nitrate tetrahydrate and sodium phosphate. Three types of alkyl ammonium bromide surfactants i.e. tetrapropylammonium bromide, tetraethylammonium bromide and tetramethylammonium bromide were used to regulate the nucleation and crystal growth. The synthesized powders were characterized by XRD, SEM and FTIR. The effect of the various alkyl ammonium bromide surfactants on the phase formation, particle size and morphology of the hydroxyapatite powders has been investigated and reported.

Abstract: Ceramic membranes having nano sized pores have great potential for gas separation at high temperature due to their good thermal stability. Moreover, nanoporous silicon carbide membrane has potential application under hydrothermal condition at high temperature. In this research, nanoporous SiC membrane has been developed on the porous alumina plate using preceramic polymers as CVD precursor at 850oC. The preceramic polymer was characterized with Si29 NMR, FT-IR, GC and TGA. The prepared SiC membrane was characterized with SEM and EDS. The hydrogen permeability and selectivity toward nitrogen gas were measured using a GC.

Abstract: This paper presents a numerical simulation of Automobile Shredder Residue (ASR) chips motion and combustion in a cement works precalciner. The work was done using the commercial computational fluid dynamic (CFD) code FLUENT. The aim of this work is to develop an understanding of the processes within the percalciner to aid in the prediction of ASR chip aerodynamic and combustion behaviors for its use as an alternative fuel. The effects of the mutual interactions between ASR chips were simulated by discrete phase modeling approach, while ASR combustion was simulated by the finite rate devolatilization models. A useful approach to simulate the characteristics of turbulent gas-particle flow, heat transfer and ASR combustion process in a precalciner has been demonstrated.

Abstract: The possible utilization of automobile shredder residue as a fuel in the cement kiln process was investigated. The detailed characteristics of the automobile shredder residues were investigated in terms of it’s chlorine content as a fuel feed and its circulation in cement kiln. For estimation of the chlorine content in the cement kiln system, the Weber model which is one of the circulation material’s forecast model was used. From the results, we estimated the chlorine by-pass rate should be 1 ~ 2 percent, for maintaining the present level of chlorine content’s on the hot-meal of the cement kiln system.