• Journal of the Mineralogical Society of Korea
• /
• v.21 no.1
• /
• pp.27-35
• /
• 2008

Characterization of mineralogy and nanocrystals of ingredient materials of $Lumilite^{(R)}$ used for water treatment was made using optical microscopy, XRD, SEM, FTIR, and XRF analyses. Constituent minerals identified by XRD and microscope are clinoptilolite, illite, quartz, and albite, characterized by dense and fine texture. The cross section of nanocrystals with the size $70{$\sim}100\;nm$ is generally round or subround. Numerous spheroids with few nanometers in diameter are extensively formed on the surface of nanocrystals. Bulk chemistry is $SiO_2$ $74.22{\sim}75.65\;wt.%$, $Al_2O_3$ $13.25{\sim}13.72\;wt.%$, CaO $4.23{\sim}5.15\;wt.%$, with other major elements being minimal. When heated to $700^{\circ}C$, the crystal structure was mostly destroyed, though it persisted to $500^{\circ}C$. It is likely that high capacity and applications of $Lumilite^{(R)}$ for water treatment are originated from its structural properties such as development of nanocrystals and various tiny pores.

• Korean Journal of Materials Research
• /
• v.10 no.7
• /
• pp.464-470
• /
• 2000

The compacting and sintering behavior of titanium powders containing oxygen in the range of 1980~8450 ppm was examined. The powders were prepared by the hydride-dehydride (HDH) and by the deoxidation by solid state(DOSS) methods. Their compaction density ranged from 69.0% to 62.3% and decreased with the increase in the oxygen content. It was explained by the effect of oxygen on the hardness of powders. Unlike the compaction density, the oxygen content did not affect the apparent density greatly being 90.5$\pm$0.5% after sintering at $1100^{\circ}C$ for 2 hours. Their average grain size was $60\mu\textrm{m}$ and the size and distribution of pores were about the same for all cases. The hardness of sintered samples showed a linear increase with oxygen and could be expressed as VHN(sintered)= 135.5+64.3$\times$$(wt{\%}O_2)$ The exami-nation of fracture surface revealed that the ductile-brittle transition occurs at oxygen contents of 2987~5582 ppm.

• Journal of the Korea Institute of Building Construction
• /
• v.18 no.5
• /
• pp.447-453
• /
• 2018

Since 1960, Korea the town center was developed intensively due to rapid industrial development. As a result of the development, the population was concentrated in urban areas and the green area was decreased. Due to the decrease of the green area, the circulation system of the rainwater was changed, hence the rainwater was not introduced into the groundwater., On the other hand, the water on the surface of the road was changed into the water for flowing to the river and evaporation. The changes in the water flow cause many problems, and the depletion of the groundwater does not create an environment in which microorganisms and plants can live. in Korea, permeable pavement construction is increased to solve these problems, but existing pavement blocks have many problems. The pores of the permeable block are clogged due to the accumulation of dust or whitening phenomenon, and the permeability is lost. In this study, the solution of the problems of existing permeable block were suggested by using polymer and artificial permeable pipe, and strength, permeability and service life are increased, The relationship between the substitution rate of the polymer and the mixing ratio of the artificial permeable pipe was analyzed.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.9
• /
• pp.604-609
• /
• 2020

There are various methods of finishing concrete surfaces, and when considering workability, the spray method is effective, but rebound occurs. The allocation of rebound occurrence control should be adjusted according to the materials used. Thus, a basic study was conducted on multiple techniques for reducing the rebound incidence that are suitable for surface finishing materials containing a photocatalyst. A prior study derived the reduction effect and optimal mix ratio for photocatalytic performance. Based on that study, the rebound reduction was verified according to the specifications of the content and the mechanical durability characteristics of the mixed materials. Rebound, compressive strength, flexural rigidity, and table flow tests were done. The flow was fixed at 170±10 mm considering the workability of the mortar spray equipment. For the experimental variables, the rebound number was adjusted to the silica sand variables relative to the cement weight, and silica sands No. 5 and No. 7 were used. The results show the highest compression strength in the final S-1 variable, and the amount of rebound was minimized. These results were sufficiently filled with the bindings of the silica pores, which increased the binding force between the aggregates, resulting in a lower amount of rebound.

• Journal of Conservation Science
• /
• v.27 no.3
• /
• pp.313-322
• /
• 2011

The floral wall of Lee Sang-beom's House and Atelier, which is No. 171 of the Registrated Cultural Heritage was conserved. In addition, materials characteristics and manufacturing technique have revealed through the scientific analysis. As a result of the analysis, samples were divided into three sections; the support layer that is made from block bricks, the paint layer and the cement mortar layer on the paint layer for the reinforcement of the construction. The higher layer lies, the finer grains it has. Furthermore, a little it was generated a small quantity of pores and calcium carbonates ($CaCO_3$) generated due to aeration of cement mortar. The patterns of letters, animals and plants pattern were expressed in the paint layer by relief and openwork. The results of qualitative analysis of the pigments of the paint layer were detected components of carbon black (C), Fe oxide ($Fe_2O_3$) and oyster shell white ($CaCO_3$, or quicklime). On the other hands, as the conservation of the floral wall, stainless frames were set up for the structural stability, the cement mortar were removed from the surface and the partly damaged and cracked areas were filled with KSE Filler A, B.

• Journal of Periodontal and Implant Science
• /
• v.32 no.3
• /
• pp.489-500
• /
• 2002

The purpose of this study was to evaluate newly fabricated tricalcium phosphate(TCP)/chitosan microgranuls as bone substitutes. TCP/chitosan microgranules were fabricated by dropping TCP-chitosan suspension into the NaOH/ethanol solution. The size of microgranules could be controllable via airflow rate. PDGF-BB was loaded into the fabricated granules via freeze-drying methods(300 ng/20 mg). To evaluate cell proliferation, cultured osteoblasts cell lines(MC3T3-El) was dropped on the BioOss(R), chitosan microgranules, TCP/chitosan microgranules and cultured for 1, 7 , 14, and 28 days. Scanning electron microscopic observation was done after 7 days of culture and light microscopic examination was done after 28 days of culture. PDGF-BB release from the microgranules was tested. Rabbit calvarial defects(8 mm in diameter) were formed and chitosan, TCP/chitosan, PDGF-TCP/chitosan microgranules, and BioGran(R) were grafted to test the ability of new bone formation. At SEM view, the size of prepared microgranules was 250-1000 um and TCP powders were observed at the surface of TCP/chitosan microgranules. TCP powders gave roughness to the granules and this might help the attachment of osteoblasts. The pores formed between microgranules might be able to allow new bone ingrowth and vascularization. There were no significant differences in cell number among BioOss(R) and two microgranules at 28 day. Light and scanning electron microscopic examination showed that seeded osteoblastic cells were well attached to TCP/chitosan microgranules and proliferated in a multi-layer. PDGF-BB released from TCP/chitosan microgranules was at therapeutic concentration for at least 1 week. In rabbit calvarial defect models, PDGF-TCP/chitosan microgranules grafted sites showed thicker bone trabeculae pattern and faster bone maturation than others. These results suggested that the TCP/chitosan microgranules showed the potential as bone substitutes.

• Journal of Korean Society of Environmental Engineers
• /
• v.36 no.2
• /
• pp.109-112
• /
• 2014

A porous ceramic which has fine porosity and small specific gravity is made with Cenosphere and Ball Clay under condition of $1,250^{\circ}C$ in calcination temperature and 30 minutes of calcination time. The average size of porous ceramic was about $2.5{\times}10^{-5}$ m and pores are well developed. The void-fraction of porous ceramic was 67.1% under the input of Cenosphere and Ball clay with the weight ratio of 100 to 5. However, as weight ratio of Ball Clay increased to 20, 40, 100, the void fraction decreased to 58.4, 56.7, 47% respectively. When the weight ratio of Cenosphere and Ball Clay was 100 to 100, the apparent density of porous ceramic was $1.04g/cm^3$. which is twice the density when the weight ratio of Ball Clay was 5. On the other hand, absorption rate decreased by at least 100%. In condition of weight ratio of Cenosphere and Ball Clay was 100 to 100, compressive strength of porous ceramic was 30 (MPa), improve by about 76% or more when the weight ratio of Ball Clay was 5.

• Journal of Korean Society of Environmental Engineers
• /
• v.35 no.6
• /
• pp.415-421
• /
• 2013

To increase specific surface property of activated carbon fiber(ACF), chemical activation(CA) using alkali metals and surface treatment(ST) using oxidant was widely used. The CA and ST process developed micro-pore on the surface of ACF by chemical reaction of the alkali metals and oxidative of oxidant, respectively. To improve the efficiency of CA process for developing micro-pores on the surface of ACF, the ST process was adopted as an pre-treatment method. After treatment of ST process, ACF properties was investigated depending on the ST pre-treatment process. FT-IR, TG and elemental analysis of the ACF are carried out, and an adsorption property of ACF was also evaluated using toluene(which in typical volatile organic matter). Once the single CA process is used, the surface area and adsorption capacity of ACF were increased from 1,483 to 1,988 $m^2/g$ and from 0.22 to 0.27 $g_{-Tol.}/g_{-ACF}$, respectively. On the other hands, once the ST and CA processes are used successively, the surface area and adsorption capacity of ACF are greatly increase(where the surface area is 2,743 $m^2/g$ and the adsorption capacity is 0.37 $g_{-Tol.}/g_{-ACF}$). It indicates that the combined process of ST and CA can improve the surface process properties of ACF.

• Journal of Korean Society of Environmental Engineers
• /
• v.39 no.6
• /
• pp.325-331
• /
• 2017

Adsorption experiments of carbon dioxide were performed on ZSM5 and Molecular Sieve 13X (MS13X) impregnated with Monoethanol Amine (MEA). Adsorption efficiency of $CO_2$ was investigated in a U type packed column with GC/TCD. The adsorption capacities of adsorbents are estimated in the temperature range of $30-80^{\circ}C$. The modified adsorbents was characterized by BET surface area, $N_2$ adsorption/desorption isotherms, X-ray diffraction and FT-IR. Surface analysis results showed that the impregnation method did not affect the crystallinity of any adsorbents. BET surface area of the MS13X impregnated amine decreased to $19.945m^2/g$ from $718.335m^2/g$. These reults showed that amine molecules were filled with the pore volume in MS13X, as a results restricting access of nitrogen into the pores. The MEA modified MS13X showed improvement in $CO_2$ adsorption capacity over the ZSM5 impregnated with MEA. The MS13X-MEA showed the highest adsorption capacity due to physical adsorption and chemical adsorption by amino-group content. This results also showed that adsorption capacity of MS13X-MEA increases with the temperature range of $60-80^{\circ}C$ compared with pristine MS13X.

• Applied Chemistry for Engineering
• /
• v.10 no.6
• /
• pp.843-847
• /
• 1999

In this research, C/SiC composites, i.e. activated carbon coated with SiC obtained from dichlorodimethylsilane(DDS) and hydrogen, have been made by chemical vapor infiltration(CVI) in a fluidized bed reactor. Activated carbons of sizes of 4~12, 12~20, and 20~40 mesh were used. After deposition the surface area, the amount and the shape of deposit of each sample were observed at different concentrations of reactant DDS, sizes of activated carbon, reaction pressures and reaction times. The experimental results showed that uniform deposition in the pores of sample was obtained at a lower concentration of DDS and a lower pressure. Additionally, from the observation that the pore diameter and the surface area have minimum values at a certain time of deposition, it was known that deposition occurred inside of the pore at first and then on the outside of particle. Small particles of SiC were deposited uniformly on the surface of activated carbon at lower DDS concentrations and lower reaction pressures. The results were confirmed by SEM, TGA, the pore size distribution analyzer and BET.