• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.401-404
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• 2008

In the present investigation, a high precision thermal imprint system for micro ceramic products was developed and the net-shape manufacturing of multi-layer ceramic reflector for LED (Light Emitting Diode) was conducted with a precision metal die. Workpiece used in the present investigation were the multi-layer laminated ceramic sheets with pre-punched holes. The cavity with arbitrary angle was formed on the circular and rectangular holes of the ceramic sheets. During the imprinting process, the ambient temperature of the imprint system was kept over the transition temperature of the ceramic sheet and then rapidly cooled. The results in this paper show that the present method can be successfully applied to the fabrication of very small size hole array for ceramic reflector in a one step operation.

• Korean Journal of Materials Research
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• v.27 no.11
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• pp.583-589
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• 2017

Ceramic ink-jet printing has become a widespread technology in ceramic tile and ceramicware industries, due to its capability of manufacturing products on demand with various designs. Generally, thermally stable ceramic inks of digital primary colors(cyan, magenta, yellow, black) are required for ink-jet printing of full color image on ceramic tile. Here, we synthesized an aqueous glass-ceramic ink, which is free of Volatile organic compound(VOC) evolution, and investigated its inkjet printability. $CoAl_2O_4$ inorganic pigment and glass frit were dispersed in aqueous solution, and rheological behavior was optimized. The formulated glass-ceramic ink was suitably jetted as single sphere-shaped droplets without satellite drops. After ink-jet printing and firing processes, the printed glass-ceramic ink pattern on glazed ceramic tile was stably maintained without ink spreading phenomena and showed an improved scratch resistance.

• Transactions of Materials Processing
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• v.16 no.5 s.95
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• pp.396-400
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• 2007

LTCC(Low Temperature Co-fired Ceramic) which offers a good performance to produce multilayer structures with electronic circuits and components has emerged as an attractive technology in the electronic packaging industry. In LTCC module fabrication process, the lamination and the sintering are very important processes and affect the electrical characteristics of the final products because the processes change the permittivity of ceramics and the dimension of the circuit patterns which have influences on electronic properties. This paper discusses the influence of lamination pressure and sintering temperature on the permittivity and the dimensional change of LTCC products. In the present investigation, it is shown that the permittivity increases along with increasing of the lamination pressure and the sintering temperature.

• Journal of the Korean Ceramic Society
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• v.17 no.3
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• pp.151-157
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• 1980

Crystallization phenomena of glasses of fused natural basalt rocks were studied by DTA, X-ray phase analysis, electron microscopy, and other techniques. Crystallization was catalyzed by the addition of either chromite ore or $P_2O_5$, both up to 5 wt %. Various heat treatments were used, and their influences on controlling the microstructures and properties of the products were studied to develop high strength glass-ceramic material of the $CaO-Al_2O_3(Fe_2O_3)-MgO(FeO)-SiO_2$ system from the domestic basalts. Magnetite precipitates were found to be a nucleation initiator in every case of the crystallization. Diopside, anorthite, clinoenstatite and monticellite were identified as silicate crystalline phases contained in the crystallized products. The crystallite size was in the range of 0.1-2.5$\mu\textrm{m}$. The fine crystallites were approximately cubic, but large crystallites were either plate or needle shape. The thermal expansion coefficient, microhardness and modulus of rupture of glass-ceramics were ranged from 78.5 to 81.8$\times$10-7 cm/cm/$^{\circ}C$, from 820 to 930kg/$\textrm{mm}^2$, and from 1800 to 2800kg/$\textrm{cm}^2$, respectively.

• Journal of the Korean Home Economics Association
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• v.48 no.1
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• pp.97-110
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• 2010

The purpose of this study was to identify development strategies of high value-added cultural products in order to help promote Jeonnam cultural tourism festivals. In order to achieve this purpose, we carried out a market survey of cultural products sold in cultural tourism festivals held successfully within the Jeonnam area.The subjects of this study were local festivals which were labeled as cultural tourism festivals by the Ministry of Culture, Sports and Tourism from 2000 to 2008. The results of this study were as follows: Firstly, a store survey was conducted to analyze the categories of products on offer. As a result, the most frequent product was accessories (46.2%), followed by clothing and miscellaneous goods (25.2%), ceramic products (14.8%), interior decoration products (9.1%), and stationery (4.6%). Secondly, in the design motif used for cultural products, most products did not contain festival or local images. Cultural products with festival images made up 47.2% of the range, while only 2.3% of products on offer contained local imagery. The remaining 50.3% of cultural products for sale did not use festival or local images. Finally, in terms of materials used, most products used metal (36.7%), followed by textiles (32.9%), ceramic (13.8%), wood (6.2%), plastic (6.2%), paper (3.6%), and leather (0.2%). For price range, 52.4% of product were equal to or below 10,000 won, followed by 33.1% between 10,000-30,000 won. The results of this study showed that the cultural products of Jeonnam festivals lacked symbolism of the region or festival itself. Furthermore, items and the price ranges were not diverse enough. A possible solution would be to address this short coming, but more importantly, design a marketing and commercial strategy tailored towards the promotion of cultural products which contain both regional and festival imageries.

• Journal of the Korean Ceramic Society
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• v.19 no.3
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• pp.229-235
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• 1982

This paper deals with the electric insulator in terms of its toughness. The toughness is determined by the notched beam test and it is found that the toughness of electric insulator largely depends on the porosity as well as crystalline phases. This study also indicates that the Korean electric insulators have improved its toughness for last seven years and the recent products show comparable properties with imported insulator.

• Journal of the Korean Ceramic Society
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• v.28 no.10
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• pp.757-766
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• 1991

These powder properties were investigated and prepared of ultrafine Mn-Zn ferrite powder by Direct-wet process from variation of oxidation condition. H2O2 oxidation the products were ultrafine spherical particles of about 400${\AA}$ in diameter and superparamagnetics. H2O2 and Air oxidation, Coexistance ultrafine spherical particles of about 400${\AA}$ and cubic particles of about 1000${\AA}$. The products were constructed of superparamagnetic and ferromagnetic particles, and Magnetization were about 30 emu/g. Air Oxidation, Above 6 hr Air 120 ι/hr and 4 hr of Air 180 ι/hr were uniform cubic particles of above 1000${\AA}$. The products were ferromagnetic particles and Magnetization of above 45 emu/g.

• Journal of the Korean Ceramic Society
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• v.49 no.4
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• pp.328-332
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• 2012

Etch rates of Si and high purity SiC have been compared for various fluorocarbon plasmas. The relative plasma resistance of SiC, which is defined as the etch rate ratio of Si to SiC, varied between 1.4 and 4.1, showing generally higher plasma resistance of SiC. High resolution X-ray photoelectron analysis revealed that etched SiC has a surface carbon content higher than that of etched Si, resulting in a thicker fluorocarbon polymer layer on the SiC surface. The plasma resistance of SiC was correlated with this thick fluorocarbon polymer layer, which reduced the reaction probability of fluorine-containing species in the plasma with silicon from the SiC substrate. The remnant carbon after the removal of Si as volatile etch products augments the surface carbon, and seems to be the origin of the higher plasma resistance of SiC.

• Journal of the Korean Ceramic Society
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• v.53 no.1
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• pp.63-67
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• 2016

Mineral hydrate is a new insulation material that compensates for the defects of existing materials. Mineral hydrate is made of inorganic ingredients; therefore, it is nonflammable. The porous structure of mineral hydrate makes the material lightweight and insulating. Mineral hydrate insulation and similar products have been studied and manufactured in Korea and abroad. However, these insulation materials need to improve in terms of strength. In this study, basalt fiber was used to enhance the strength. In order to observe the property changes, compressive strength, heat conductivity, and specific gravity were measured and XRD pattern analysis was performed. These tests confirmed that basalt fiber was effective at improving the strength and lowering the heat conductivity of mineral hydrate insulation.

• Journal of the Korean Ceramic Society
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• v.43 no.2 s.285
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• pp.69-73
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• 2006

A full retention of the tetragonal phase with coarse grains $(50\~60\;{\mu}m)$ was possible with the specimen $ZrO_2-1.9\;mol\%\;Y_2O_3$. In these coarse grains, $\{101\}_t$ annealing twins were frequently observed, although they do not exist in the usual fine grained specimens. The morphology and growth rate of the isothermally formed individual products are studied at an optical microscopic level. The habit planes of both products are also identified by performing two-surface trace analysis on the grains whose orientations are determined by the Electron Back Scattering Pattern (EBSP) method. The morphologies of isothermal martensite were well-defined thin plates and lenticular types. The growth rate in their longitudinal directions was quite slow and temperature-dependent. A two-surface trace analysis, incorporated with the EBSP method, identified the habit planes near $\{013\}_c$, in agreement with previous reports obtained from TEM works.