• Journal of the Korean Ceramic Society
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• v.41 no.8
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• pp.588-592
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• 2004

Effect of the UO$_2$ powder characteristic changes by dynamic milling method on the density was investigated. particle size decreased and its shape was changed from irregular to round form with increasing milling time (0∼8 h), while its specific surface area and O/U ratio increased. It was shown that the sintered density decreased, while green density increased with these powder characteristic changes. It could be considered that this decrement was affected by increased O/U ratio of the UO$_2$ powder during dynamic milling.

• Electrical & Electronic Materials
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• v.7 no.4
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• pp.306-311
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• 1994

In this study, the influence of the powder sintering, the 2nd sinteiing and the grinding time on the Superconducting properties in the Bi(Pb)SiCaCuO Superconductor has been studied. From the analysis of SEM and XRD patterns, it was known that the sample prepared by the process of powder sintering has a porous microstructure with the critical temperature(Tc) below 77K, while the sample prepared by the 2nd sintering has a highly oriented microstructure with the Tc above 100K. The Critical Current Density(Jc) of the sample prepared by the 2nd sintering was better than the sample prepared by the process of powder sinteiing, but it's Jc, was low in practical use. Also, the effect of grinding time from 0[min] to 120[min] was investigated. As the grinding time is increased, the samples degraded from high-Tc phase to low-Tc phase and nonsuperconducting phases.

• Journal of the Korean Ceramic Society
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• v.35 no.10
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• pp.1055-1060
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• 1998

The effects of particle size distribution have been investigated on the high frequency low loss Mn-Zn fer-rites. The particle size distribution was controlled by milling time. Zirconia ball and engineering plastic jar were employed to avoid iron contamination from the milling media. As increasing the milling time BET value was increased from 0.55 to 3.21m2/g and mean particle size was decreased from 2.1 $\mu\textrm{m}$ to 1.0$\mu\textrm{m}$ The large specific surface area of initial powder resulted in the high density of sintered core. However starting powders with high BET lead to inhomogeneous grain growth as well as poor electromagnetic pro-perties at sintering temperature above 1300$^{\circ}C$.

• Journal of Energy Engineering
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• v.28 no.1
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• pp.1-9
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• 2019

In the flue gas desulfurization process of the coal-fired power plant, the grinding efficiencies of the limestone as the sorbent for desulfurization were compared after BWI and HGI measurements. As a result, the grinding index of the domestic desulfurization limestone were linear inversely proportional relationship with decreasing BWI was observed with increasing HGI. There was a difference in grinding efficiency depending on the chemical composition and crystal structure. Therefore, it is considered that when grinding ability of limestone is measured, the grinding property of the sample can be confirmed even by using HGI which can be measured more easily than BWI which is difficult to measure and takes a long time. The desulfurization efficiency can be improved by selective utilization of limestone depending on the crushing characteristics.

• Journal of the Korean Wood Science and Technology
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• v.40 no.3
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• pp.156-163
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• 2012

This research has been carried out to investigate the characteristics of cellulose nanofibers manufactured from domestic lignocellulosic materials by mechanical grinding method. The continuous grinding process was effective for loosening cell wall structure, with increasing grinding time, much smaller nanofibers were observed. Filtration time was linearly increased with increasing grinding time for all experimental materials. Relative crystallinity of cellulose was not changed by grinding process, but increased by delignification treatment. Tensile property of fiber sheets was drastically improved with increasing grinding time. Fibers sheets obtained from delignified cone stalks showed an excellent tensile strength. Consequently, it is considered that this study presented some effective information for manufacturing cellulose nanofibers with domestic plantation resources.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.4 s.48
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• pp.543-548
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• 2004

For pearl pigments used for splendor or gloss effect of make-up products, especiallv point make-up products like eye-shadow and blusher, we studied the variation of particle size distribution by the grinding time and by the binder used as a binding agent. In this study. high speed mixer was used and the particle sire distribution was measured by using the light scattering method. In case of pearl pigments, its median diameter of $5{\;}{\mu}m$, the particle size was reduced to 4.6 um when it was ground for 120 s. When it was applied for the pearl pigment of $45{\;}{\mu}m$, the particle size was reduced to $27{\;}{\mu}m$. We confirmed that the latter was reduced more largely and the original gloss was reduced too. For the binder, we studied the correlation between particle size of raw material and grinding time. We also investigated the effects of the binder contents on the variation of particle size distribution of products by aggregation of particles.

• Cement Symposium
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• no.31
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• pp.198-204
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• 2004

온라인 분쇄입도 조절 콘트롤(Insitec) 시스템은 시멘트의 생산공정상에 시멘트입도를 직접 측정하고 측정된 데이터를 이용하여 공정을 제어할수 있는 새로운 방법으로서, 세계적으로 50여개의 시멘트 생산 현장에 이러한 시스템이 설치되어 있다. 시멘트의 생산공정은 일반적인 분쇄공정과는 차별되는 나름데로의 특성이 있으므로 이를 개발한 Malvern Instrument사(영국)에서는 시멘트 공장의 특성에 적합한 시스템을 개발해왔다. 우선 가장 이상적인 Instec 시스템의 설치를 위해서는 다음과 같이 3단계의 절차가 필요하다. 첫 단계로서 공정상의 변수로 적용되어야 될 변화를 찾아 모니터링하고 연관시키는 것이다. 그 다음 단계에서, 시멘트 생산공정을 24시간 동안 모니터링하여 설정 값과 측정 값과의 차이점과 원인을 찾아내어 요인을 결정하게 되고, 마지막 단계에서는 현장에 장비를 설치, 상기의 반복과정을 마무리하고 공정을 제어할 수 있게 하는 것이다. 시멘트 생산공정에서 분쇄기, 분급기 및 송풍기 등의 회전수 증가와 감소, 시멘트조성의 변화와 같은 중요한 공정상의 변화가 있을 경우, 이로 인해 생기는 입도의 영향은 Insitec 시스템의 입도관리에 기록되게 된다. 본 논문에서는 스페인의 Jerez에 있는 Holcim 플랜트에 설치된 Insitech를 이용하여 운전상의 변수 등을 측정하고 제어하며 시멘트 공정에 활용하는 방안에 대한 연구를 소개한 것이다.

• Journal of Life Science
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• v.9 no.2
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• pp.194-200
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• 1999

Grinding aid is a necessary unit operation when the raw materials are handled in solid form, and the purpose is to improve the bioavailability by reducing the particle size. For the particle design of pefloxacin, the dry planetary ball-mill was used. With the drying process, 330 g of zirconia ball with its size of 2 mm in diameter and 10 g of pefloxacin were transferred to the pot and mixed well. The mixture was ground at 112 rpm (60 Hz) for 15, 30, and 60 min, respectively. The most satisfactory grinding products were generated at 15 min of grinding time for their particle size. The volume mean diameter $\X_50$ of the grinding products was 2.97 $\mu$m. X-ray diffraction (XRD), differential scanning calorimeter (DSC), and infrared spectroscopy (IR) patterns were relatively unchanged before pulverizing pefloxacin and in the progress of grinding. Thus, these results suggest that this pulverizing method can be used for grinding products without evident effect on stability of the drug pefloxacin. Dissolution test was carried out to set up the optimal detective condition against residual antibacteria of fish by HPLC. The grinding pefloxacin for 15 min is most effective in dissolution test.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.2
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• pp.71-77
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• 2015

High-Performance Liquid Chromatography (HPLC) is a widely used method for measuring the concentration of chlorophyll a as an indicator for estimating phytoplankton biomass and primary production and also for identifying carotenoids to determine phytoplankton composition. However, tissue grinding procedure requires a lot of time and experience in the analysis of multiple sample. Accordingly, we measured the concentrations of photosynthetic pigments before and after the grinding, in order to understand the grinding effects on the quantitative analysis of chlorophylls and carotenoids using samples from southwestern East Sea. When tissue grinding procedure was omitted, we found that Chl a concentrations were underestimated up to 45% in average. Also, concentrations of Zeaxanthin, 19'-butanoyloxyfucoxanthin, 19'-hexanoyloxyfucoxanthin, biomarkers of pico and nano-size phytoplankton, were underestimated up to maximum 77~85% without grinding. We found that the smaller the phytoplankton, the bigger underestimation of their biomarker pigments concentration is likely to happen due to the incomplete extraction. Thus, tissue grinding procedure should be included for HPLC analysis in all cases, to prevent the underestimation of not only Chl a but also carotenoids pigments.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.813-820
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• 2010

The vertical roller mill is important for machine grinding and mixing various crude materials in the process of producing Portland cement. A vertical roller mill is subjected to cyclic bending stress because of the roller load. Because of the cyclic bending stress, only $4{\times}10^6-8{\times}10^6$ cycles are achieved instead of $4{\times}10^7$ cycles. The stress also causes fractures at the edge of grinding path of the outer roller. The expenses incurred in repairing the grinding path amounts to 30% of the total maintenance cost. Therefore, it is desirable to redesign the vertical roller mill in order to reduce the expenses incurred in repairing the roller. In this study, artificial neural networks (ANNs) were applied in order to solve the multiobjective optimization problem for vertical roller mills by using the function approximation ability of ANNs. To learn and generalize ANNs, the maximum and minimum stresses were estimated from the results of the finite-element analysis of a vertical roller mill. Thus, ANNs could be applied to solve the multiobjective optimization problem.