• Applied Chemistry for Engineering
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• v.26 no.6
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• pp.706-713
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• 2015

Graphite foams (GFs) were prepared by adding different amounts of mesophase pitch (MP) into polyvinyl alcohol-acrylic acid (PVA-AAc) solution followed by the heat treatment. It was confirmed that the pore diameters of GFs were controlled by the slurry concentration, which was the mesophase content added in polymer solution, and their thermal conductivity and compressive strength were also controlled by porosities of GFs formed at different conditions. The resulting GFs in this study had the highest thermal conductivity of $53.414{\pm}0.002W/mK$ and compressive strength of $1.348{\pm}0.864MPa$ at 0.69 in porosity. The thermal conductivity of MP based GFs increased approximately 23 times higher than that of using isotropic pitch based GFs due to the developed graphitic structure.

• Applied Chemistry for Engineering
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• v.29 no.1
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• pp.122-126
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• 2018

Mesoporous molecular sieves were prepared by the reaction of $Na_2SiO_3$ and $H_2SiF_6$ using nonionic micelle templates in an aqueous solution. Well-crystalline mesoporous molecular sieves were obtained after several seconds at atmospheric conditions. Powder samples exhibited d-spacing of 3.8-5.1 nm with the sharpness of the d00l peak, showing well-crystalline mesoporous molecular sieves, pore size distributions of 2.5-3.1 nm and large specific surface areas of $290-1,018m^2/g$, depending on types of surfactants. SEM images of samples showed well-divided spherical particles with an uniform size of ${\sim}0.5{\mu}m$ and TEM images demonstrated uniform pores with a worm hole shape.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.3
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• pp.17-22
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• 2003

This paper presents an experimental investigation of a reversible colloidal seismic damper, which is statically loaded, The porous matrix is composed from silica gel (labyrinth or central-cavity architecture), coated by organo-silicones substances, in order to achieve a hydrophobic surface. Water is considered as associated lyophobic liquid. Reversible colloidal damper static test rig and the measuring technique of the static hysteresis are described. Influence of the pare and particle diameters, particle architecture and length of the grafted molecule upon the reversible colloidal damper hysteresis is investigated, for distinctive types and mixtures of porous matrices, Variation of the reversible colloidal damper dissipated energy and efficiency with temperature, pressure, is illustrated.

• Applied Chemistry for Engineering
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• v.29 no.2
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• pp.248-251
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• 2018

Catalytic pyrolysis of the waste paper cup containing coffee residual (WPCCCR) was performed using a fixed bed reactor and pyrolyzer-gas chromatography/mass spectrometry (Py-GC/MS). Non-catalytic pyrolysis of WPCCCR produced a large amount of oil together with gas and char. The use of both HZSM-5 and HY decreased the yields of oil and increased the yield of gas due to the additional catalytic cracking. Owing to the acidic catalytic properties of HZSM-5 and HY, catalytic Py-GC/MS analysis of WPCCCR increased the selectivity to aromatic hydrocarbons in product oil. Owing to properties of HZSM-5 having a stronger acidity and medium pore size, the catalytic pyrolysis of WPCCR over HZSM-5 produced much larger amounts of aromatic hydrocarbons than that of using HY.

• Korean Journal of Plant Tissue Culture
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• v.27 no.2
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• pp.149-154
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• 2000

Embryogenic suspension cultures were initiated using embryogenic callus from immature inflorescence explants (Aralia cordata Thunb.) cultured on solid MS medium containing 1 mg/L 2,4-D for 8 weeks and then the embryogenic callus was proliferated in liquid MS medium containing 1 mg/L 2,4-D. After sieving the suspensions (pore size 270$\mu$m), embryogenic cells were cultured in liquid MS medium with cytokinins (kinetin, BA, zeatin) for two weeks. When the embryogenic cells were transferred to liquid MS basal medium, primary somatic embryos were developed after 5 weeks of culture. Secondary embryos were developed directly from the primary torpedo and cotyledonary embryos cultured in solid MS basal medium. Frequency of secondary embryogenesis was higher on medium containing 2 mg/L kinetin than the other cytokinins. Plant regeneration was highly recorded by placing secondary cotyledonary embryos induced from primary cotyledonary embryos in MS medium containing 2 mg/L kinetin or 2 mg/L zeatin (25.4% and 28.6%, respectively). The plant regeneration from secordary embryos was prohibited by tertiary embryogenesis.

• Journal of the Korean Ceramic Society
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• v.34 no.1
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• pp.45-55
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• 1997

Various kinds of amorphous silicates were used as raw materials to synthesize building materials based on calcium silicate hydrates. Relationships between the reactivities of silicates and castabilities of the building materials were investigated. In addition, effects of the reactivities of silicates on the mechanical properties of casted specimens were studied by analyzing microstructures and hydrates produced. As the reactivity of silicate increase, the press castability increases and the crystal size of hydrate and pore size also increase. For the mechanical properties, the flexural strength increases with decreasing crystal size and densifing microstructure. The compressive strength is greatly dependent on the den-sification of microstructure rather than crystal size of hydrate. Based on the results, diatomous ma-terials are desirable due to high reactivity and formation of densified microstructure. Slag and fly ash may be partially used as raw materials with amorphous silicates to manufacture building materials based on calcium silicate hydrates.

• Korean Chemical Engineering Research
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• v.44 no.4
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• pp.417-423
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• 2006

A series of amine functionalized MCM-41 catalysts were prepared by aminopropyltrimethoxysilane grafting and their catalytic performance in Knoevenagel reaction of selected substrates was investigated. Water resistant and catalytically active amine grafted MCM-41 was prepared by post-synthetic silylation using methyltrimethoxysilane ; hydrogen bonding of the water molecules formed during the condensation reaction to the active N group was suppressed, which led to high TON of the reaction. Amine functionalized MCM-41 prepared by coating method produced high conversion, but the TON of the catalyst was much lower than that of the amine grafted MCM-41; pore volume of the functionalized MCM-41 decreased substantially and large portion of the immobilized amine is believed to be hydrogen bonded to each other, which can result in decrease in the basicity of the N group. A secondary amine group was prepared by room temperature condensation between aminopropylsilane and chloropropylsilane, and the MCM-41 grafted with the secondary amine group demonstrated the highest catalytic activity among the catalysts prepared.

• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.275-280
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• 2009

The direct incorporation of vanadium into the three-dimensional(3-D) cubic Ia3d mesostructure designated as V-KIT-6 was carried out hydrothermally using a Pluronic P123 and n-butanol as the structure-directing mixture, tetraethylorthosilicate(TEOS) as the silica source and $NH_4VO_3$ as the vanadium source. The obtained V-KIT-6 showed a very high specific surface area ${\sim}1,000m^2/g$ with tunable pore diameters in narrow distribution of sizes ~6.0 nm. The coordination and nature of V sites in V-KIT-6 are characterized by $^{51}V$-spin-echo NMR analysis. The calcined V-KIT-6 materials showed excellent catalytic activity in the direct oxidation of styrene using tert-butyl hydroperoxide(TBHP) as an oxidant.

• Membrane Journal
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• v.30 no.3
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• pp.200-204
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• 2020

1,3,5-benzenetricarbonyl trichloride is a chemical substance in which three acyl chlorides are located at 1,3,5 position in the benzene ring, and is an important chemical for the area where the good physical and chemical properties are required through high degree of crosslinking. In particular, it is possible to form a three-dimensional structure having a certain pore size, it is used in various separation and purification fields. However, the high reactivity of acyl chloride has the advantage of a fast reaction rate, which means that it is difficult to control chemically to have a certain performance in other aspects. Therefore, in this study, we observed how the chemical change of 1,3,5-benzenetricarbonyl trichloride affected the membrane performance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.183-189
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• 2018

In this study, the bond strength between concrete and metal films was investigate according to changing water content ratio of substrate concrete by pull-out test in order to develop the new finishing design methods for building structures using the metal films. The following conclusions were obtained as a result of the studies. It was find that the colour of metal did not change before and after the metal spraying. Also, the water content ratio of substrate concrete must be controlled under 10% weight to confirm the standard bond strength of finishing material to concrete. 2.5 MPa. To enhance the bond strength between concrete and metal films, it is very effective to strengthen the concrete surface using the agent which strengthen the concrete surface and seal the pore of metal film by the sealing agents. Therefore, the control of concrete surface treatment and water content ratio are necessary to secure the bond strength of metal films.