• Journal of the Korean Ceramic Society
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• v.34 no.12
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• pp.1213-1220
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• 1997

Effect of particle size of alumina and amount of talc on tape casting and densification behaviors of alumina-talc system were investigated. The pseudoplastic behaviors of slurries increased with increase in amount of talc addition and decrease in alumina particle size. In case of using coarse alumina powder, densification of specimens were accelerated with increase of sintering temperature and amount of talc addition. On the contrary, fine alumina powder retarded of rearrangement of alumina particle during liquid phase sintering due to premature densification of alumina matrix region before formation of liquid phase and then densification of specimens were suppressed with increase of sintering temperature and amount of talc addition.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.41 no.3
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• pp.1-7
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• 2009

Talc as a coating pigment has been developed in order to replace GCC and clay for matte grade and has received much attention due to various advantages including good gravure printability. In order to elucidate the effects of talc on gravure printability, model papers were produced with three kinds of coating talc whose particle size and brightness are different. Physical properties related to surface and structure and the gravure printability of the sample were tested. Coating color with talc showed lower viscosity than that with clay. For both matte and art grades, talc tended to give lower gloss than day. The smaller the particle size of talc, the better properties in the coating color viscosity and water retention. When the particle size of talc was small enough, the surface roughness of the coated paper produced with talc was similar to that with clay while larger talcs produced rougher surface than clay. On top of that, application of talc improved compressibility and gravure printability of coated paper.

• Journal of the Korean Ceramic Society
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• v.35 no.12
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• pp.1308-1315
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• 1998

Effects of particle size of alumina on densification behavior during liquid-phase sintering of alumina-talc system were investigated with emphasis on particle rearrangement process. In the case of using coarse alu-mina powder densiication of specimens was rapidly accelerated after formation of liquid phase due to easy particle rearrangement process with addition of talc and increase of sintering temperature. On the contrary when fine alumina powder was used premature densification of alumina matrix region formed before for-mation of liquid phase rigid skeleton structure and then it seemed to inhibit rearrangement process during crease of sintering temperature. As results the densification of specimens using coarse alumina powder was higher than that of the case of using fine one.

• Journal of the Mineralogical Society of Korea
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• v.31 no.1
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• pp.47-55
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• 2018

Talc, hydrous magnesium phyllosilicate, is one of the most popular industrial minerals due to their chemical stability and adsorptivity. While micro-sized talc has long been used as a filler and coating, nano-sized talc recently is attracting attention as additives for improving the stability of nanocomposites. In this study, we produced the nano-sized talc powder by mechanical method using high energy ball mill and investigated the changes in particle size and crystallinity with increasing milling time up to 720 minutes. X-ray diffraction results show that the peak width of talc gradually as the milling proceeded, and after 720 minutes of pulverization, the talc showed an amorphous-like X-ray diffraction pattern. Lase diffraction particle size analysis presents that particle size of talc which was ${\sim}12{\mu}m$ decreased to ${\sim}0.45{\mu}m$ as the milling progressed, but no significant reduction of particle size was observed even after grinding for 120 minutes or more. BET specific surface area, however, steadily increases up to the milling time of 720 minutes, indicating that the particle size and morphology change steadily as the milling progressed. Scanning electron microscope and transmission electron microscope images shows that layered particles of about 100 to 300 nm was aggregated as micro-sized particles after pulverization for 720 minutes. As the grinding time increases, the particle size and morphology of talc continuously change, but the nano-sized talc particles form micro sized agglomerates. These results suggest that there is a critical size along the a, b axes in which the size of plates is reduced even though the grinding proceeds, and the reduction of plate thickness along the c axis leads the increase in specific surface area with further grinding. This study could enhance the understanding of the mechanism of the formation of nano-sized talc by mechanical grinding.

• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.961-967
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• 1998

In order to improve the optical properties and printability of paper, various fillers are used in papermaking. This study was performed to investigate several fillers-precipitated calcium carbonate(PCC), ground calcium carbonate(GCC), and blends(PCC/talc or micro-talc(MVP) and GCC/talc or micro-talc(MVP)-for their effects on various newsprint properties. Results obtained from the study were summarized as follows ; 1) PCC treatment gave about 16.8% higher retention than GCC treatment at the filler level of 5% and the retention of filler in the handsheet increased as average particle size of mixed filler was increasing($PCC{\leq}GCC<MVP<talc$). 2) PCC treatment kept opacity more highly than no filler treatment and opacity decreased as average particle size of mixed filler was increasing. 3) Independent treatment of PCC kept tear strength more effectively than GeC did, and tear strength increased as average particle size of mixed filler was increasing. 4) Independent treatment of pee kept tensile strength more highly than other treatments and Gee treatment kept tensile strength highly than pee treatment under mixed filler treatment. 5) Burst strength under PCC treatments decreased linearly as average particle size of mixed filler was increasing. 6) Compared "With non-filler treatment, filler treatment gave much better printability.

• Journal of the Mineralogical Society of Korea
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• v.32 no.3
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• pp.201-211
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• 2019

The particle size and crystallinity of fault gouge generally decreases with slip. Phyllosilicates including talc are known to be present in fault gouge and play an important role in fault weakening. In particular, the coefficient of friction varies depending on the presence of a water molecule on the surface of mineral. The purpose of this study is to investigate the effect of talc on fault weakening by changing the water content and dehydration behavior of talc before and after grinding, which systematically varied particle size and crystallinity using high energy ball mill. Infrared spectroscopy and thermal analysis show that the as-received talc is hydrophobic before grinding and the water molecule is rarely present. After grinding up to 720 minutes, the particle size decreased to around 100 ~300 nm, and in talc, where amorphization proceeded, the water content increased by about 8 wt.% and water molecule would be attached on the surface of talc. As a result, the amount of vaporized water by heating increased after grinding. The dihydroxylation temperature also decreased by ${\sim}750^{\circ}C$ after 720 minutes of grinding at ${\sim}950^{\circ}C$ before grinding due to the decrease of particle size and crystallinity. These results indicate that the hydrophobicity of talc is changed to hydrophilic by grinding, and water molecules attached on the surface, which is thought to lower the coefficient of friction of phyllosilicates. The repeated slip throughout the seismic cycle would consistently lower the coefficient of friction of talc present in fault gouge, which could provide the clue to the weakening of matured fault.

• Journal of the Korean Ceramic Society
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• v.14 no.4
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• pp.215-225
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• 1977

In this study, we are observe to the sagger which is composed of cordierite-mullite system. And especialy, we investigated the characteristics of the body which composed of Chamotte-Kaolin-Plastic clay-Talc (or Clinochlore) system and Chamotte-Kaolin-Plastic clay-Agalmatolite-Talc (or Clinochlore) system. The obtained results are as follows. 1. Modulus of rupture and apparent porosity were improved by particle size of talc and clinochlore in order that -16 mesh, -6 mesh, 6-16 mesh. 2. When the body composed of talc, the modulus of rupture was increased as firing temperature was rising up but composed of clnochlore, it was reversed. 3. When added to the agalmatolite, firing shrinkage, modulus of rupture and apparent porosity were improved. 4. Mineral phases of samples fired at 125$0^{\circ}C$ above consist of cordierite, mullite and $\alpha$-cristobalite.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.41 no.3
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• pp.8-12
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• 2009

According to a previous study, talc as a coating pigment can improve the viscosity and the water retention of coating color, the compressibility of coating layer, and hence gravure printability. Talc is also well known for its larger particle size than other pigments, which implies that less binder may be need due to its smaller specific surface area. This study investigated the possibility of reducing binder content for matte grade paper. Coating color was prepared with the Cotalc-2000, which showed the best properties in the previous study. The binder content was varied and the effect of binder content on the physical properties of coated paper and the gravure printability was investigated. It was shown that binder content could be reduced when talc was used as a coating pigment. The reduction in binder content did not influence gloss, roughness and the print density of coated paper but showed improvement in paper porosity, compressibility and missing dot.

• Journal of Chest Surgery
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• v.56 no.5
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• pp.353-358
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• 2023

Background: Malignant pleural effusion affects many patients with advanced cancer. When chemotherapy or radiotherapy fails to relieve malignant pleural effusion and related symptoms, drainage and pleurodesis can help. Although surgical talc pleurodesis is the most widely used method, Viscum album, which has been recently used in surgical or bedside procedures, has demonstrated significant results and is as effective as talc. This study aimed to determine the most effective agent and procedure. Methods: Between January 2015 and July 2022, chemical pleurodesis was performed in 137 patients with malignant pleural effusion, using a V. album surgical procedure in 48, a V. album bedside procedure in 55, and a talc surgical procedure in 34 patients. We reviewed patients' clinical responses and disease progression after chemical pleurodesis. Results: The success rate was not significantly different among the V. album surgical procedures (91.7%), V. album bedside procedures (83.6%), and talc surgical procedures (91.2%). However, the total drainage amount and tube insertion duration in both Viscum groups were more effective than those in the talc group. Furthermore, the bedside Viscum group showed significantly lower post-pleurodesis pain scores than the other 2 groups. Conclusion: According to our results, talc and V. album can be considered ideal agents for chemical pleurodesis. However, Viscum pleurodesis showed safer outcomes in terms of ensuring quality of life than talc. Additionally, the bedside Viscum group showed significantly lower pain scores than the other groups. Hence, patients for whom surgical procedures are inappropriate can undergo bedside Viscum pleurodesis without diminishing the therapeutic effect.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2011.04a
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• pp.251-263
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• 2011

This study was carried out in order to investigate the effect of pre-coating layer on top-coating layer. The coated paper with five different formulations were prepared. The properties of coated paper were measured and correlation between pre and top-coated layer was evaluated. Paper gloss was increased with addition of clay and GCC that has smaller particle size. Roughness was decreased with using smaller particle GCC, clay and talc. The highest thickness was obtained with talc. Brightness and whiteness of pre-coated layer were affected to top-coated layer. GCC 60 shows the highest and ununiform water adsorption during 1sec. The adsorption was higher with increasing coated weight. Talc shows the excellent water adsorption properties due to its wettability. These results indicate that final printability and properties of top coating layer can be controlled with adjusting pre-coating layer.