• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.490-499
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• 1998

This study was initiated to investigate the applicability of sludge from water or waste water treatment on the crop cultivation. Sludge is generated in the process of water and wastewater treatment process in large quantity. The sludge can cause many environmental problems. we have a many available treatment methods of sludge However, these methods still shortcomings and are not. The composition of typical municipal sludge contains organics and inorganics. The organics components are normally burnt in high temperature and mainly inorganics components are left after thermal treatment process. For the production of artificial media, chabazite was used as additive, and the mixed material was thermally treated in the firing kiln at 800~1,10$0^{\circ}C$ for about 10 minutes. The physical and chemical characteristics of artificial media were analyzed and it showed that the artificial media could be used as a media for plants and soil conditioner for farmland. The concentrations of the toxic heavy metals in the media were lower then those in the soil quality standard for farmland. This study illustrated that the artificial media production process, and introduced how to produce it's possible application as a media for Plant growth.

• Korean Journal of Crystallography
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• v.3 no.1
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• pp.1-8
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• 1992

The morphology of lead titanate powders prepared by sol-gel and coprecipitation techniques was investigated as a function of firing temperature and soaking time. PbTiO3 precursor powders were derived from a mixed solution of lead nitrate and titanium tetrachloride at 40℃ to 43℃ and pH of 9.0 to 9.7, and fired at temperatures 350-1000℃ for 1-10h in air. An increase of particle size and agglomeration with increasing calcination temperature and duration could be observed. By annealing sol-gel derived powder at 700℃, the tially-formed acicular(and/or prismatic) primary particles transformed to polyhedral shape with soaking time, and further soaking caused coarsening the polyhedral particles with rounded edges. However, the morphology of the coprecipitated powders was not varied during crystallization.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.363-364
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• 2009

The activity and stability test of low-temperature(850 $\sim$ 1,000 ${^\circ}C$) firing MgO which is expected to improve the performance of the crack resistance wee conducted and The degree of hydration for the 10% MgO-mixed cement paste was analyzed after 1day, 3days, 7days, 28days, 56days, 90days, and 180days using SEM, XRD, DSC.

• The Korean Journal of Ceramics
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• v.2 no.1
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• pp.33-38
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• 1996

In thick film resistors, the characteristics of the frit and the reaction between glass frit and conductor material play an important role for their electrical properties. In this study, various glass frits in the system of $60RO{\cdot}20SiO_2$ $15B_2O_3{\cdot}5Al_2O_3$(RO=PbO, ZnO, CdO; mole%) were mixed with $RuO_2$ and coated on 96% alumina substrate. Only the glass frit containing PbO was reacted with $RuO_2$in$RuO_{2+}$-thick film resistor and produced the new crystalline phase of $Pb_2Ru_2O_{65}$. Their electrical resistivities strongly depend on the amount of $Pb_2Ru_2O_{65}$ crystalline phase obtained, which varied with firing temperature. The sheet resistivities of these resistors were varied from $10^3\; to\; 10^6\;{\Omega}/{\Box}$ depending on heat treatment, and the absolute value of TCR was decreased as the heat treatment temperature increaed. However, $RuO_2$ did not reacted with the glass frits containing ZnO nor CdO, and the resulting showed very high sheet resistivities.

• Journal of the Korean Ceramic Society
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• v.53 no.2
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• pp.227-233
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• 2016

In order to make a highly ordered three-dimensional porous structure of titania ceramics, porogen beads of PS [Polystyrene] and PMMA [poly(methylmetacrylate)] were prepared by emulsion polymerization using styrene monomer and methyl methacrylate monomer, respectively. The uniform beads of PS or PMMA latex were closely packed by centrifugation as a porogen template for the infiltration of titanium butoxide solution. The mixed compound of PS or PMMA with titanium butoxide was dried and the dry compacts were calcined at $450^{\circ}C-750^{\circ}C$ according to the firing schedule to prepare micro- and meso- structures of polycrystalline titania with monodispersed porosity. Inorganic frameworks composed of $TiO_2$ were formed and showed a three Dimensionally Ordered Microstructure [3DOM] of $TiO_2$ ceramics. The pulverized particles of the $TiO_2$ ceramic skeleton were characterized using XRD analysis. A monodispersed crystalline micro-structure with micro/meso porosity was observed by FE-SEM with EDX analysis. The 3DOM $TiO_2$ skeleton showed opalescent color tuning according to the direction of light.

• Journal of the Korean Ceramic Society
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• v.46 no.4
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• pp.413-418
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• 2009

Glass systems based on Ca, Sr, Ba, and Zn modified alumino-boro silicates were investigated in order to improve the dielectric and mechanical properties of a typical LTCC (low temperature co-fired ceramic) which was developed for high frequency highly-integrated modules. The glass was prepared by a typical melting procedure and then mixed with cordierite fillers to fabricate glass/ceramic composite-type LTCC materials. The amount of cordierite filler was fixed at 50 volumetric%. For an optimal glass composition of 7.5% CaO, 7.5% BaO, 5% ZnO, 10% $Al_2O_3$, 30% $B_2O_3$, and 40% $SiO_2$ in mole ratio, the resultant LTCC composite showed a dielectric constant of 5.8 and a dielectric loss ($tan{\delta}$) of 0.0009 after firing at $900^{\circ}C$. An average bending strength of 160MPa was obtained for the optimal composition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.05a
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• pp.91-95
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• 2006

In whole world consciousness of environment maintenance have increased very quickly for the end of the 20th century. To use and disuse toxic substances have been controled at the field of industry. Also the field of lighting source belong to environmental control. And in the future the control will be strong. In radiational mechanism of fluorescence lamp mechanism is the worst environmental problem. In radiational mechanism of fluorescence lamp mercury is the worst environmental problem root. In the mercury free lighting source system the Xe gas lamp is one type. And the Ne:Xe mixing gas lamp improvements firing voltage of Xe gas lamp. Purpose and subject of this study are understand, efficiency, ideal of Ne:Xe plasma which mercury free lamp. Before ICP was designed, basic parameters of plasma, which are electron temperature and electron density, were measured and calculated by Langmuir probe data. Property of electron temperature and electron density were confirmed by changing ratio of Ne:Xe.

• Journal of the Korean Ceramic Society
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• v.39 no.12
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• pp.1119-1123
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• 2002

Nanostructured spinel NiZn ferrites were prepared by the sol-gel method from metal nitrate raw materials. Analyses by X-ray diffraction and scanning electron microscopy showed the average particle size of NiZn ferrite was under 50 nm. The single phase of NiZn ferrites was obtained by firing at 250${\circ}C$, resulting in nanoparticles exhibiting normal ferrimagnetic behavior. The nanostructured $Ni_{1-X}Zn_XFe_2O_4$ (x=0.0∼1.0) were found to have the cubic spinel structure of which the lattice constants ${\alpha}_2$ increases linearly from 8.339 to 8.427 ${\AA}$ with increasing Zn content x, following Vegard's law, approximately. The saturation magnetization $M_s$ was 48 emu/g for x=0.4 and decreased to 8.0 emu/g for higher Zn contents suggesting the typical ferrimagnetism in mixed spinel ferrites. Pure NiZn ferrite phase substituted by Cu was observed before using the additive but hematite phase was partially appeared at $Ni_{0.2}Zn_{0.2}Cu_{0.6}Fe_2O_4$. On the other hand, the hematite phase in this NiZn Cu ferrite was disappeared after using the additive of acethyl aceton with small amount. The saturation magnetization Ms of $Ni_{0.2}Zn_{0.8-y}Cu_yFe_2O_4$(y=0.2∼0.6) as measured was about 51 emu/g at 77K and 19 emu/g at room temperature, respectively.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1114-1115
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• 2006

The preparation of single-phase $CuLaO_2$ with delafossite-type structure by means of the solid-state reaction method was investigated using X-ray diffraction. The results showed that notwhistanding the fact that there was a trace of metallic copper, nearly single-phase $CuLaO_2$ was obtained by using $La(OH)_3$ as a lanthanum source and by firing the mixed powder with nonstoichiometric composition ratio of $La(OH)_3:Cu_2O=1:1.425$ in a vacuum at 1273 K for 10 h. The measurement of electrical conductivity and Seebeck coefficient showed that $CuLaO_2$ thus obtained was a p-type semiconductor and had a Seebeck coefficient of approximately $70{\mu}V/K$.

• Journal of the Korean institute of surface engineering
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• v.52 no.5
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• pp.251-257
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• 2019

Fe-9Cr-2W steels were corroded at $600-800^{\circ}C$ for up to 100 hr in ($Na_2SO_4-K_2SO_4-Fe_2O_3$)-($CO_2-0.3%SO_2-6%O_2$) mixed gas. The poor condition samples formed thick oxide scales that consisted primarily of $Fe_2O_3$ as the major oxide and $Fe_3O_4$, FeO as the minor one through preferential oxidation of Fe. Fe-9Cr-2W steels corroded fast, forming thick and non-protective scale. The scale divided into the outer and inner layer, which consisted of the outer Fe-O layer and the inner (Fe,Cr)-O layer containing some (Fe,Cr)-S.