• Tribology and Lubricants
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• v.24 no.2
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• pp.96-103
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• 2008

PTFE is generally utilized as the form of composites with adding various fillers. The purpose of this paper lies on clarifying the friction and wear properties of the PTFE coating layer on steel. Especially, the effects of PTFE powder size for coating and surface roughness of the counter material on the properties are investigated. Sliding friction and wear tests are conducted at several sliding speeds by employing two types of PTFE coating layer using different powder sizes. One type of coating layer is composed of uniform fine powder, whereas the other type is made up of mixture powder of different sizes. As results, it is found that PTFE coating layer are effective to improve the wear resistance and to reduce the friction coefficient. It is clear that PTFE coating layers are abrasively removed by asperities of the counter material during sliding contact. However, PTFE coating layer with uniform fine powder shows somewhat better wear resistance than that with mixture powder of different sizes in low sliding speed region. It can be seen that the wear of the coating layer are drastically reduced because wear fragment from counter material are transferred to the coating layer. On the other hand, friction coefficient is shown not to be directly related with PTFE powder size in coating layer.

• Korean Journal of Materials Research
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• v.23 no.4
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• pp.250-254
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• 2013

In order to increase the toughness of ZTA(zirconia toughened alumina) ceramics, the present study focused on rearrangement and densification of particles according to the particle size of the parent material. When rough alumina was used for production of ZTA, densification behavior was observed in the specimen sintered at a temperature over $1550^{\circ}C$. However, it was found that the densification behavior was occurred in the specimen sintered at $1450^{\circ}C$ when fine alumina powder was used. High relative density exceeding 98% was obtained when fine alumina powder was mixed with 15 wt% of 3Y-TZP and sintered at $1600^{\circ}C$. Also, a hardness of 1820.2 Hv was obtained when a specimen containing 10 wt% of 3Y-TZP was sintered at $1600^{\circ}C$. In the case of 3Y-TZP containing rough alumina powder that had been sintered the hardness value was around 1720.3 Hv. It was predicted that an improved toughening effect in ZTA could be achieved by using finer alumina powder as the parent material.

• Journal of Powder Materials
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• v.13 no.6 s.59
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• pp.408-414
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• 2006

[ $MoSi_2$ ] alloys with Al, B or Nb were prepared by an advanced consolidation process that combined mechanical alloying with pulse discharge sintering (complex forming) to improve the mechanical properties. Their microstructure and mechanical properties were investigated. The $MoSi_2$ alloys fabricated by complex forming method showed very fine microstructure when compared with the sample sintered from commercial $MoSi_2$ powders. Alloys made from powders milled in Ar gas had fewer silica or alumina phases as compared to their counterparts sintered from powders milled in air. In densification of the sintered body, addition of B was more effective than Al or Nb. Both Victors hardness and tensile test indicated that the alloy fabricated by the complex forming method showed better properties than the sample sintered from commercial $MoSi_2$ powders. The Al added alloy sintered from the powders milled in air had the superior mechanical properties due to the suppression of $SiO_2$ and formation of fine $Al_2O_3$ particles.

• Journal of Powder Materials
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• v.12 no.3
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• pp.179-185
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• 2005

As the electrodes of secondary battery are made with sulfur compounds, excellent electrode system of environmental non-toxicity, high specific energy density and low material cost can be obtained. In this study, the $FeS_2$ fine compound powders for active material in the battery were synthesized by mechanical alloying. Fine Fe-53.5 wt.%S powders of 450 nm of mean size were fabricated by mechanical alloying for 60 hours at the horizontal attritor. As the mechanical alloying time increases, particle size of Fe-53.5 wt.%S was decreased and steady state of Fe-53.5 wt.%S compound powders was obtained at 30 hours. Fe-53.5 wt.%S cathode shows the excellent discharge capacity (1011 mAh/g).

• The Korean Journal of Cytopathology
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• v.17 no.1
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• pp.32-37
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• 2006

The objective of this study was to evaluate the cytomorphologic features of histologically confirmed clear cell carcinoma of the ovary and to evaluate the applicability of scrape or fine-needle aspiration cytology in making an intraoperative diagnosis. We reviewed scrape or fine-needle aspiration cytology findings in tissues taken from 6 patients with clear cell carcinoma of the ovary. The cytologic diagnosis was based primarily on findings in alcohol-fixed, hematoxylin-eosin (H-E) stained smears. The formation of material resembling a basement membrane was a characteristic finding in these smears. This extracellular hyaline material was stained light pink with H-E and was frequently found within tumor cell clusters as well as in the background material. Multinucleated giant cells were found occasionally. Each tumor cell had an abundant, clear, or granular cytoplasm with a distinct cellular membrane. Scrape cytology is a simple and rapid supportive method and could be helpful in diagnosing clear cell carcinoma of the ovary, especially when marked artifacts appear in the frozen section.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.05a
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• pp.115-118
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• 2006

Nowadays the using of concrete is generalized, and construction material is demanded to be lightweight according to increasing the height and capacity of buildings. Therefore, it needs to develop the products having the great quality and various performance. Extruding concrete panel made of cement, silica source, and fiber, and it is a good lightweight concrete material in durability and thermostable. The silica of important ingredient is natural material with hish SiO2 contents and difficult in supply because of conservation of environment. On the other hand, the stone powder sludge discharged about 20-30% at making process of crushed fine aggregate and it is wasted. The stone powder sludge is valuable instead of silica ole because the stone powder sludge includes water of about 20-60%, SiO2 of about 64% and it has fine particles. This experiment is on the properties of extruding concrete panel using the stone powder sludge use instead of silica. From this experiment, we find that it is possible to replace the silica as stone power sludge up to 50%,

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.1
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• pp.65-71
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• 2007

Since pop-outs are occurred recently on concrete surface occasionally, it is needed to find out accurate causes and to suggest appropriate methods. On this study, it is investigated the occurrence mechanism of pop-outs caused by electric arc furnace Oxidizing slags as fine aggregate for concrete. As a result, it is investigated the cause of pop-outs that extremely small quantities of free CaO and free MgO in the electric furnace slag react with water to produce $Ca(OH)_2$ and $Mg(OH)_2$, so that their volumes are expanded and erupted about two times. As a resolution, it is needed to remove the potential cause of expansion by replacing the deteriorated concrete section up to the depth to secure the safe of structural element with repairing polymer mortar, especially more than 50MPa.

• The Korean Journal of Cytopathology
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• v.8 no.1
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• pp.52-56
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• 1997

Oxyphilic (Hurthle) cells have abundant eosinophilic granular cytoplasms and occur in both benign and malignant neoplasms of the thyroid gland. Most published studies described mainly oxyphilic tumors of follicular type, and reports on oxyphilic papillary thyroid carcinomas are rare. The oxyphilic variant of papillary carcinoma differs from the classic papillary carcinoma in its more aggressive biological behavior. We report a case of oxyphilic papillary carcinoma exhibiting exclusively oxyphilic cells in a follicular pattern without papillary structures. The pattern of papillary carcinoma was confirmed by fine needle aspiration material and lymph nodal metastasis, both of which revealed typicaled papillary structures with characteristic nuclear features, psammoma bodies, and oxyphilic cytoplasm.

• The Korean Journal of Cytopathology
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• v.14 no.1
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• pp.22-26
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• 2003

Cystic hypersecretory carcinoma of the breast is a rare variant of ductal carcinoma of breast, first described in 1984 by Rosen and Scott. Histologically, it is characterized by the formation of dilated ducts and cysts containing an eosinophilic secretory product resembling thyroid colloid. Cytologic findings show a few clusters of atypical ductal epithelial cells in amorphous proteinaceous material with clacking artifact. Differential diagnosis include mucinous carcinoma and benign mucocele-like tumor. We present two cases of fine needle aspiration cytology of cystic hypersecretory intraductal carcinoma of the breast with a review of the literature.

• Proceedings of the KWS Conference
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• 1999.10a
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• pp.297-298
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• 1999

Cemented carbides material (WC-Co hard alloy) were recognized very important and expensive tool or die assembly parts because of compose for the main elements of rare metal (W and Co etc). This research was developed to separate and recover of WC fine powder contained by WC-Co materials. Recycling process was a new method named by the Tin impregnation for decobaltification on cemented carbides. This reaction occurred to product a brittle Co-Sn intermetallic compounds, thereafter it carried out by acid cleaning solution and physical milling or powdering. New process was able to recover about 60％ WC fine powder from 1 to 5 ${\mu}{\textrm}{m}$.