• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.535-541
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• 2012

ALC was fabricated using cement, lime, quartzite and a foaming agent via a hydrothermal reaction. ALC has various hydrothermal reaction products and many pores. The properties and colors of ALC surfaces were changed by various factors during ALC fabrication process. This study tested various staying times to analyze these phenomena. It was found that the staying time of green body influenced the properties of hydrothermal products and color of ALC surface. The longer staying time of green body, the lower tobermorite content and cumulative loss weight. An increase in holding time changed color and decreased whiteness of ALC surface. The relationship between whiteness and cumulative loss weight was very high (Coefficient, r = 0.95). It was surmised that tobermorite content was an important factor for enhancement of whiteness However, ettringite and quartzite did not contribute to whiteness.

• Journal of the Korean Ceramic Society
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• v.54 no.6
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• pp.470-477
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• 2017

Ceramic processing to fabricate 3D complex ceramic structures is crucial for structural, energy, environmental, and biomedical applications. A unique process is ceramic stereolithography, which builds ceramic green objects from CAD files from many thin liquid layers of powder in monomer, which are solidified by polymerization with a UV laser, thereby "writing" the design for each slice. This approach directly writes layers in liquid ceramic suspension and allows one to fabricate ceramic parts and products having more accurate, complex geometries and smooth surfaces. In this paper, both UV curable materials and processes are presented. We focus on the basic material principles associated with free radical polymerization and rheological behavior, cure depth and broadening of cured lines, scattering at ceramic interface and their corresponding simulation. The immediate potentials for ceramic AM to change industry fabrication are also highlighted.

• Journal of Powder Materials
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• v.16 no.6
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• pp.431-437
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• 2009

Various inorganic fillers improve the thermal conductivity and physical properties of organic products. Alumina has been used a representative filler in the heat radiation sheet for the heat radiation of electric device. The high filling rate of alumina increases the thermal conductivity and properties of products. We successfully developed the spherical alumina by flame fusion process using the oxygen burner with LPG fuel. In the high temperature flame (2500$\sim$3000$^{\circ}C$) of oxygen burner, sprayed powders were melting and then rotated by carrier gas. This surface melting and rotation process made spherical alumina. Especially effects of chemical composition and particle size of stating materials on the melting behavior of starting materials in the flame and spheroidization ratio were investigated. As a result, spheroidization ratio of boehmite and aluminum hydroxide with endothermic reaction of dehydration process was lower than that of the sintered alumina without dehydration reaction.

• Journal of the Korean Ceramic Society
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• v.27 no.2
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• pp.149-154
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• 1990

Before benefication of Okchun feldspar, all kinds of Fe-compounds and mafic minerals which were included in feldspar were studied. Also to produce 30/140mesh products as glass materials, optimum grinding condition and degree of liberation were studied. Fe-compounds were Biotite and Limonite, and these were existed along the cleavage. Optimum grinding time was 2min. and at this time weight percent of 30/140mesh products was 72.7% and degree of liberation at this particle size was 91.5%.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.10a
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• pp.102-105
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• 1995

The membrane separation process is being utilized to save energy in various fields such as the food, biotechnology, chemical, enviromental fields. Especially the use of ceramic membrane among various inorganic membranes is expected to expand to their excellent thermal, chemical and mechanical resistance. In this presentation, we would like to explain our ceramic membrane CEFILT MF for microfiltration and CEFILT UF for ultra-filtration, and the purification of fermentation products as the application example using CEFILT MF.

• Journal of the Korean Ceramic Society
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• v.54 no.3
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• pp.228-234
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• 2017

This work was achieved on the preparation of antimicrobial ceramic hybrid polyethylene films with natural chamomile extracts. The antimicrobial activity and various physicochemical properties of the prepared films were evaluated. Various natural products demonstrated antimicrobial activity. Among them, chamomile extracts showed strong activity and no cytotoxicity rather than that of the natural extracts. Porous ceramic materials were synthesized and demonstrated loading and controlled release of natural antimicrobial extracts. Furthermore, chamomile loaded ceramic hybrid films showed antimicrobial activity that was maintained for over 15 days.

• The Korean Journal of Ceramics
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• v.5 no.1
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• pp.35-39
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• 1999

For many years, alkali activated blast furnace slag cement containing no ordinary portland cement has received much attention in the view of energy saving and its many excellent properties. We examined the structural change of slag glass which was activated by alkali metal compounds using IR spectroscopy. The properties of hydrated products and unhydrated slag grains was characterized by XRD and micro-conduction calorimeter. Ion concentration change in the liquid during the hydration of blast furnace slag was also studied to investigated the hydration mechanism.

• Journal of the Korean Ceramic Society
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• v.35 no.9
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• pp.939-944
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• 1998

The formation microstructure and properties of novel ceramic composite materials by active filler con-trolled polymer pyrolysis were investigated. Polymethlsiloxane filled with W is of particular interested be-cause of the formation of ceramic bonded hard materials (WC-$W_{2}C$-$S_{1}OC$) for wear resistant applications. Highly metal-filled polymer suspensions were prepared and their conversion to ceramic composites by an-nealing in $N_{2}C$ atmosphere at 1000-$1600^{\circ}C$ were studied. Dimensional change porosity and phase distribution (filler network) were analyzed and correlated to the resulting material properties. Microcrystalline com-posites with the filler reaction products embedded to the resulting material properties. Microcrystalline com-posites with the filler reaction products embedded in a silicon oxycarbide glass matrix were produced. De-pending on the pyrolysis conditions ceramic composites with a density up to 95 TD% a hardness of 7-8.8GPa Yong's modulus of 220-230 GPa a fracture toughness of 6-6.8$MPam^{1/2}$ and a flexual strength of 380-470 MPa were obtained.

• Journal of the Korean Ceramic Society
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• v.31 no.12
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• pp.1437-1442
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• 1994

Self propagating synthesis and thermal explosion of combustion reactions were applied to Al/K2Cr2O7/Al2O3 system as the first stage for a production of magnesia-chromium refractory. Several factors related to products made by two combustion reactions were considered and properties of products were characterised. Two processes were required to preheat upto at least 80$0^{\circ}C$ for the thermal explosion and the self propagating synthesis. These processes were so violent and explosive that alumina as diluent was added to the system in order to absorb the reaction heat and reduce the reaction rate. The products consisted of crystal phases of KAl5O8, Cr2O3, Al2O3, K2CrO4, and K2Al2O4.3H2O. The amount of KAl5O8 and K2Al2O4.3H2O crystal phases of products were decreased with further addition of alumina.

• Journal of the Korean Ceramic Society
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• v.54 no.6
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• pp.478-483
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• 2017

The advantage of ceramic ink-jet printing technology is the accurate and fast printing process of digital images for various products. For digital ink-jet printing applications, ceramic ink requires proper viscosity and surface tension, along with dispersion stability of the inorganic pigments. The purpose of this study is the formulation of an environment-friendly ceramic ink with a water-based system; using nano-sized $CoAl_2O_4$ pigment as a raw material, ink should have dispersion stability to prevent nozzle clogging during ink-jet printing process. In addition, the surface tension of the ceramic ink was optimized with the polysiloxane surfactant according to the surface tension requirement (20 - 45 mN/m) for ceramic ink-jet printing; by adjusting the viscosity with poly ethylene oxide, jetting behavior of the ceramic ink was investigated according to changes in the physical features through drop watcher measurement.