• Journal of the Korean Ceramic Society
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• v.14 no.3
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• pp.163-168
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• 1977

As a wet chemical drying process "hot petroleum drying method" was applied and developed for preparing uniformly fine oxide powder with high purity and sinterreactivity. Using this method solution of sulfates was dried in hot petroleum bath (~17$0^{\circ}C$) to sulfate powder from which corresponding mullite doped by Fe3+ ion was formed. Particle size, shape, decomposition by heat, and phase identification of sulfate andoxide powders determined by DTA, TGA, X-ray diffraction, analysis and electron microscopy: sulfate powder prepared by this drying method is an intimate mixture of the amorphous form of uniformly and finely distributed spherical particles (0.05-0.1$\mu$). Mullitization with the sulfate powder occurs at 110$0^{\circ}C$ in air. The morphology of mullite particle made by firing the sulfate powder at 135$0^{\circ}C$ in oxygen atmosphere is granular of 0.1-0.3$\mu$ in size. This drying process proved to be a very effective method for preparing fine, homogeneous, and highly sinterreactive multicomponent oxide powder without conventional ceramic process of mixing, milling, and granulating. This process can be also applied for preparing electronic ceramic materials which are requisite for high purity and homogeneity.mogeneity.

• Journal of the Korean Ceramic Society
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• v.40 no.7
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• pp.696-701
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• 2003

The grinding efficiencies of silica powder in a small scale stirred ball mill were investigated by energy consumption estimate. Comparing with a non-treated silica powder and a heating treated silica powder, it was found that a silica powder cooled in room temperature after heating treatment at 600∼900$^{\circ}C$ consumed lower grinding energy than non-treated silica powder, and a silica powder quenched after heating treatment consumed lower grinding energies about 52∼62%, in case of dry grinding. Additionally, if heating treated silica powder grind in wet method, energy consumption will be decreased about 40% than in dry grinding, and the dependency of the particle size to the grinding efficiency, quenching significantly improved it.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.8
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• pp.1287-1294
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• 2003

The wear process of end mill is so complicated process that a more reliable technique is required for the monitoring and controlling the tool life and its performance. This research presents a new tool wear monitoring method based on the sound signal generated on the machining. The experiment carried out continuous-side-milling for 4 cases using the high-speed-steel end mill under wet condition. The sound pressure was measured at 0.5m from the cutting zone by a dynamic microphone, and was analyzed at frequency domain. As the cutter impacts the workpiece surface, a situation of farced vibration arises in which the dominant forcing frequency is equal to the tooth passing frequency of the cutter. The tooth passing frequency appears as a harmonics form, and end mill flank wear is related with the first harmonic. It is possible to detect end . mill flank wear. This paper proposed the new method of the end mill wear detection.

• Journal of the Korean Ceramic Society
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• v.29 no.10
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• pp.822-826
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• 1992

SiO2 doped sapphire single crystals were grown by Verneuil method using feed material which prepared by adding SiO2 in Al2O3. Crystal growing were attempted with varing doping amount of SiO2 from 0.01 to 1.0 wt% and when the doping amount of SiO2 were 0.01~0.04 wt%, single crystals could be attained. Starting materials for feed powder were 99.99% purity alumina and extra pure SiO2 powder. Mixing these two materials by wet milling for 24 hours and drying the mixture and then was calcined at 900~110$0^{\circ}C$ for 2~4 hours. The grown crystals had yellowish color and were somewhat transparent. During growing process the flow range of oxygen was 5~7.5ι/min and of hydrogen was 13~25ι/min, the average growth rate was 7.0~11 mm/hr. The pressure of gases were fixed at 5psi. The color of crystal was appeared and mechanical property of sapphire was developed by doping of SiO2.

• Journal of the Korean Ceramic Society
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• v.47 no.5
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• pp.439-444
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• 2010

The usual ceramic process of mixing and milling in state of oxide of $ZrO_2$ and $CeO_2$ was adopted in wet process to manufacture Ce-TZP in this study. The maximum dispersion point of every slurry manufactured with mixture of $ZrO_2$ and $CeO_2$ was neat at pH10. The stable slurry in average particle size of 90 nm can be manufactured when it is dispersed with use of ammonia water and polycarboxylic acid ammonium. The sintered Ce-TZP ceramics manufactured with addition of $CeO_2$ less than 10 mol% was progressed to the fracture of specimen due to the monoclinic phase existence more than 30% at the room temperature. More than 99% of tetragonal phase was created for the sintered body with addition of $CeO_2$ beyond 18 mol%, but the mechanical property degrade on the entire specimen was brought due to the $CeO_2$ existing above 3%. Consequently, the optimal Ce-TZP combined in oxide state was identified in 16 mol% of $CeO_2$ contents.

• Journal of Powder Materials
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• v.19 no.1
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• pp.13-18
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• 2012

This study has been performed on the full density sintering of Fe nanopowder and the surface hardening by plasma ion nitriding. The Fe sintered part was fabricated by pressureless sintering of the Fe nanopowder at $700^{\circ}C$ in which the nanopowder agglomerates were controlled to have 0.5-5 ${\mu}m$ sized agglomerates with 150 nm Fe nanopowders. The green compact with 46% theoretical density(T.D.) showed a homogeneous microstructure with fine pores below 1 ${\mu}m$. After sintering, the powder compact underwent full densification process with above 98%T.D. and uniform nanoscale microstructure. This enhanced sintering is thought to be basically due to the homogeneous microstructure in the green compact in which the large pores are removed by wet-milling. Plasma ion nitriding of the sintered part resulted in the formation of ${\gamma}$'-$Fe_4N$ equilibrium phase with about 12 ${\mu}m$ thickness, leading to the surface hardening of the sintered Fe part. The surface hardness was remarkably increased from 176 $H_v$ for the matrix to 365 $H_v$.

• Korean Journal of Materials Research
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• v.29 no.4
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• pp.264-270
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• 2019

As a case study on aspect ratio behavior, Kaolin, zeolite, $TiO_2$, pozzolan and diatomaceous earth minerals are investigated using wet milling with 0.3 pai media. The grinding process using small media of 0.3 pai is suitable for current work processing applications. Primary particles with average particle size distribution D50, ${\sim}6{\mu}m$ are shifted to submicron size, D50 ${\sim}0.6{\mu}m$, after grinding. Grinding of particles is characterized by various size parameters such as sphericity as geometric shape, equivalent diameter, and average particle size distribution. Herein, we systematically provide an overview of factors affecting the primary particle size reduction. Energy consumption for grinding is determined using classical grinding laws, including Rittinger's and Kick's laws. Submicron size is obtained at maximum frictional shear stress. Alterations in properties of wettability, heat resistance, thermal conductivity, and adhesion increase with increasing particle surface area. In the comparison of the aspect ratio of the submicron powder, the air heat conductivity and the total heat release amount increase 68 % and 2 times, respectively.

• Korean Journal of Food Science and Technology
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• v.36 no.3
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• pp.393-397
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• 2004

Rice was steeped at elevated temperatures of $40,\;50,\;or\;60^{\circ}C$ for 2 hr, and physicochemical properties of starches isolated from wet-milled rice flour were investigated. Steeping at elevated temperatures slightly decreased lightness of rice starch, while increased yellowness and redness. Average granule size of rice starch was decreased by steeping treatment. Swelling power and solubility increased as temperature increased. Starch from rice steeped at $40^{\circ}C$ displayed highest swelling power and solubility. Differential scanning calorimetry data of starch obtained from steeped rice at $60^{\circ}C$ showed increased onset and peak temperatures, with narrower gelatinization temperature range, suggesting partial annealing effect. Pasting properties of starch measured by Rapid Visco-Analyzer indicated increased peak viscosity due to rice steeping at $40^{\circ}C$. Peak and breakdown viscosities decreased at $50\;and\;60^{\circ}C$, whereas setback and final viscosities increased.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.11 no.1
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• pp.11-21
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• 2013

The Geyoungju Ca-bentonite with dry density of 1.6 g/$cm^3$ has been considered as a standard buffer material for the disposal of high level waste in KAERI disposal system design. But it had relatively lower thermal conductivity compared with other surrounding materials, that was one of key parameters to limit the increase of the disposal density in the disposal system. In this study, various additives were selected and mixed with the Ca-bentonite in different mixing methods in order to increase the thermal conductivity from 0.8 W/mK to 1.0 W/mK. As an additive, CNT (Cabon Nano Tube), graphite, alumina, CuO, and $Fe_2O_3$ were selected, which are chemically stable and have good thermal conductivity. As mixing methods, dry hand-mixer mixing, wet milling and dry ball mill mixing were applied for the mixing. Above all, the ball mill mixing was proved to be most effective since the produced mixture was most homogeneous and showed higher increase in the thermal conductivity. From this study, it was confirmed that the thermal conductivity for the Geyoungju Ca-bentonite could be improved by adding small amount of highly thermal conductive material to 1.0 W/mk. In conclusion, it was believed that the experimental results will be valuable in the disposal system design if the additive effects on the swelling and permeability on the compact bentonite are also approved in further studies.

• Korean journal of food and cookery science
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• v.16 no.6
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• pp.593-601
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• 2000

Seven domestic wheat cultivars, Suwon 261, Suwon 265, Eunpa, Kobun, Alchan, Olgru, and Kumgang, and a standard wheat, ASW(Australian Standard White Wheat), were compared in noodle-making properties. The ash contents of domestic wheats and flours were 0.1-0.3% higher than that of ASW. Therefore, domestic wheats required the control of ash contents during milling process. The protein contents which suggest the flour gluten content were 10.32, 11.3, and 9.57% in Suwon 261, Suwon 265, and Kumgang cultivars, respectively. Valorimeter values of Eunpa, Olgru, and Kumgang which indicate the dough formation time and stability were similar to that of ASW. Resistance rate of domestic wheats was lower than that of ASW. Maximum viscosity in Amylograph for Eunpa, Olgru, and Kumgang were in the range of 500-800BU, which were suitable for making noodles. Increase in weight and volume of Olgru noodle was negatively correlated with protein content. Turbidity was not positively correlated with weight and volume increase, but domestic cultivars except Suwon 265 and Eunpa showed a similar turbidity with ASW. The mechanical properties of wet and dry noodles were evaluated by TPA test before and after cooking. Springiness and cohesiveness of wet noodles increased by cooking, and the domestic cultivars showed higher values than ASW. Springiness and cohesiveness of dry noodle were not increased by cooking in any cultivars. Gumminess, chewiness and hardness of domestic wheat cultivars showed higher values than that of ASW. In the tensile test, wet noodles showed no difference between domestic cultivars and ASW. But dry noodles of domestic wheat cultivars showed higher values than ASW. In the color test for lightness, redness and yellowness, there were no differences between flour and dough of domestic wheat cultivars and ASW. In the sensory evaluation, Kumgang wheat cultivar was the most preferred among the wet and dry noodles of other domestic wheat cultivars and ASW. These results suggested Kumgang wheat cultivar to be a practical wheat variety for noodle-making.