• Journal of the Korean Magnetics Society
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• v.6 no.1
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• pp.21-27
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• 1996

The effects of various manufacturing conditions on the characteristics of metal particle tape using ultra-fine metal powder were investigated. As functions of kneading conditions and milling solid contents. coating thickness, orientation, calender and curing conditions. various properties of the tapes were studied. By the consideration of physical and eletromagnetic properties of the tapes, optimum process conditions were determined. As a result of above investigations, we concluded that manufacturing processes were very important factor in addition to dispersion behavior of particles for achieving maximum properties of the metal particle tape.

• Journal of the Korean Ceramic Society
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• v.53 no.1
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• pp.93-98
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• 2016

Cold plasma and heat treatment were selected as technologies to reduce unburned carbon in fly ash to less than 1.0%. Both cold plasma and heat treatment made it possible to eliminate unburned carbon to less than 1.0%. In the case of fly ash, which almost entirely eliminated unburned carbon with an ignition loss of 0.5%, heat treatment caused adhesion among particles and the BET specific surface area rapidly decreased as the mean particle size increased. On the other hand, with cold plasma, unburned carbon elimination caused the BET specific surface area to decrease and, as no adhesion occurred among particles, the mean particle size became small. Also, cold plasma treatment allowed small spherical particles confined within the unburned carbon particles to be released with the elimination of the unburned carbon frame, so that the quantity of fine particles had a tendency to slightly increase.

• Journal of the Korean Ceramic Society
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• v.53 no.1
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• pp.7-12
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• 2016

In this paper, we have developed a simple, new and economical carbonation method to synthesize a pure form of aragonite needles using dolomite raw materials. The obtained aragonite Precipitated Calcium Carbonate (PCC) was characterized by XRD and SEM, for the measurement of morphology, particle size, and aspect ratio (ratio of length to diameter of the particles). The synthesis of aragonite PCC involves two steps. At first, after calcinated dolomite fine powder was dissolved in water for hydration, the hydrated solution was mixed with aqueous solution of magnesium chloride at $80^{\circ}C$, and then $CO_2$ was bubbled into the suspension for 3 h to produce aragonite PCC. Finally, aragonite type precipitated calcium carbonate can be synthesized from natural dolomite via a simple carbonation process, yielding product with average particle size of $30-40{\mu}m$.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.1
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• pp.13-18
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• 2006

The magnetic abrasive machining has been developed as a new finishing technology to obtain a fine surface of workpiece. In this paper, a static magnetic field method and a magnetic abrasive brush which has many technical advantages, are applied for the magnetic abrasive machining. In the experiment, some items such as finishing time, ratio of the magnetic abrasives to Fe-powder, motor revolutions per minute, and motor ratio revolutions per minute are tested. The results of this study have shown the fact that the burr height is mostly affected by the finishing time and the abrasive ratio. Also, it has been found that the magnetic abrasive machining is a possible new technology for the deburring.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.93.2-93.2
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• 2010

Recently, printing and coating technologies application fields have been expanded to the energy field such as solar cell. One of the main reasons, why many researchers have been interested in printing technology as a manufacturing method, is the reduction of manufacturing cost. In this paper, We fabricated CIGS solar cell thin film layer by doctor blade methods using synthesis of CIS precursor nanoparticles ink on molybdenum (Mo) coated soda-lime glass substrate. Synthesis CIS precursor nanoparticles ink fabrication was mixed Cu, In, Se powder and Ethylenediamine, using microwave and centrifuging. Using multi coating process as we could easily fabrication a fine flatness CIS thin-film layer ($0.7{\sim}1.35{\mu}m$), and reduce a manufacture cost and process steps. Also if we use printing and coating method and solution process in each layer of CIGS solar cell (electrode, buffer), it is possible to fabricate all printed thin-film solar cell.

• Journal of the Korean Ceramic Society
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• v.56 no.6
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• pp.521-525
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• 2019

A study was conducted to investigate the possibility of a composite material containing a composite resin as a matrix and hydroxyapatite (HAp) powder as a substitute material for tooth repair. As the content of HAp increased, hardness value (111.9 HV at 9%) increased and flexural strength (73.3 MPa at 9%) decreased. Observation of the microstructure after immersion in a simulated body fluid (SBF) solution confirmed a dense structure due to mutual coagulation and curing. It was thought that fine HAp recrystals were formed with the lapse of time, and they were entangled to form a condensation structure and had a dense structure. In addition, since the activity was shown by the ion migration on the surface of a tooth, it was highly likely that a biocompatible bond occurred during tooth contact. Therefore, it could be used as a substitute material for tooth repair.

• Proceedings of the Korea Concrete Institute Conference
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• 1992.10a
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• pp.1-4
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• 1992

This paper deals with the effect of siliceous slurry coating on concrete microstructure under damp environment. This material is mixed inorganic powder consisted of silica, cement and fine sand and water. Water pressure was given on the coated surface of concrete. for estimation on effect of siliceous slurry coating, microstructure of coated concrete was observed through SEM, and chemical components of crystals were analyzed with X-ray diffraction and EDX. A number of needle and fibrous crystals were produced in microstructure. And based on X-ray diffraction and EDX, needle crystal mainly consist of Al, Si, and Ca, and it is concluded to be ettringite. Fibrous crystals consist of Ca and Si, and it to be calcium silicate hydrate.

• Journal of the Korean Ceramic Society
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• v.31 no.8
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• pp.835-840
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• 1994

In this study, the synthesis of Ba2Ti9O20 powder having chemically homogeneous and highly pure fine particle size distribution was attempted by the oxalate method. And the effects of ZrO2 addition was investigated. The four compositions (X=0, 0.028, 0.048, 0.068) of Ba2(Ti9-x, Zrx)O20 were prepared by precipitation reaction of BaCl2, TiCl4, and ZrOCl2, with oxalic acid and NH4OH acting as a precipitating agent and a pH regulator respectively, in aqueous solution. In case of 4.8 mol% ZrO2 addition, the single phase Ba2Ti9O20 was obtained at 120$0^{\circ}C$ and its dielectric properties was excellent showing K=40.5, Q=4621 at 5.4 GHz.

• The Korean Journal of Ceramics
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• v.3 no.2
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• pp.129-133
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• 1997

Fine powder of $\alpha$-tricalcium phosphate, tetracalcium phosphate and dicalcium phosphate were mixed together to prepare self-setting cements which form hydroxyapatite, one of the well-known biocompatible materials, as the end of products of hydration. Hardening behaviour of the cements was examined at the temperature range of 37~$70^{\circ}C$ and 150~$250^{\circ}C$ under the normal and hydrothermal condition respectively. The conversion of cements into hydroxyapatite was significantly improved ast elevated temperature and the paste was strengtheed by interlocking of hydroxyapatite crystals, indicating that the strength is determined by microtexture rather the amount of conversion of cements into hydroxyapatite.

• Journal of the Korean Ceramic Society
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• v.26 no.5
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• pp.691-697
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• 1989

Fine TiO2 and BaTiO3 powders having spherical particles were synthesized by ultrasonic spray pyrolysis of alcoholic solution of metal alkoxide in an electric furnace heated at 400-90$0^{\circ}C$. Microstructure and composition of particles synthesized were observed by TEM and XRD respectively. Spectific surface area of powders synthesized was examined through BET specific surface area measurement. TEM observation revealed that the particle size did not change irrespective of pyrolysis temperature but decreased according to the increase of concentration and spherical particle was consisted of primary particles of about 0.02${\mu}{\textrm}{m}$. As for BaTiO3 powder, the ratio of Ti/Ba was 0.987 by EDX analysis.