• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.184-185
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• 2022

This study researched the effect of graphene nanoribbons (0.05 wt%) on cement-based materials' mechanical and electrical properties. The results were compared with the ordinary Portland cement (OPC) paste and OPC paste with the same content of carbon nanotubes. The experiment results showed that after curing for 28 days, the compressive and splitting tensile strength of the sample with graphene nanoribbons were increased by 17.8% and 6.6% compared to OPC paste, and its reinforced effect for cement-based materials was superior to carbon nanotubes. Besides, due to the excellent electrical properties of graphene nanoribbons, the sample reinforced by graphene nanoribbons had a lower electrical resistivity (135.5 Ω·m) than OPC paste (418.5 Ω·m) and paste with carbon nanotubes (175.5 Ω·m). This proved the promising application of graphene nanoribbons on cement-based materials.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.193-194
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• 2020

Recently, as the use of high-performance concrete has become common, various problems related to high-performance concrete have become an issue. Among them, self-shrinkage of cement paste due to low water cement ratio is known to cause problems in the volume stability of concrete. To improve this, studies related to the mixing technology of cement-based materials and nano materials have been actively conducted. Looking at the results of prior research related to nano material mixing technology, generally, research results have been reported in which nano materials are incorporated into cement-based materials to improve material properties1). Among them, it was shown that the mechanical performance and various types of functionality of the cement composite are expressed. Among nano materials, carbon nanotubes (hereinafter referred to as CNTs) and graphenes are used in a mixture with cement-based materials. Accordingly, this study intends to compare the mechanical properties by incorporating various CNTs and graphene into cement paste.

• Korean Journal of Materials Research
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• v.13 no.10
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• pp.663-667
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• 2003

The effects of paste materials on field emission properties in a carbon nanotube(CNT) cathode were investigated for high-efficient field emission displays. The major components in CNT paste for screen printing were a metallic Ag-paste, a dielectric glass-frit and CNT ink. The emission current from the cathode by an electron tunneling effect increased with an increase in the dielectric material fraction in the CNT paste, which is related to an increase of field enhancement factor in Fowler-Nordheim equation. The surface treatment used, after soft baking of the screen-printed CNT films, greatly affected the decrease in the turn-on field in CNT cathode and the uniformity of emission sites over the entire CNT film area.

• Journal of the Korean Ceramic Society
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• v.44 no.8
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• pp.430-436
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• 2007

Rheological properties of cement paste containing ultrafine blastfurnace slag (UBS, $9600cm^2/g$) were investigated by mini-slump test, pH meter, conduction calorimeter and coaxial cylinder viscometer. In order to improve rheological properties of the cement paste, granulated blastfurnace slag (GBS, $3500cm^2/g$) and polycarboxylate type superplasticizer (PC) were also used in this experiment. The fluidity of cement paste containing UBS was decreased. The yield stress and plastic viscosity of cement paste was increased with increasing UBS. But the rheological properties were improved when GBS and PC were added to UBS blended cement paste. In the relationship between the yield stress and the plastic viscosity or the mini-slump value, the yield stress of the cement paste was proportional to the plastic viscosity of it. However the cement paste mini-slump value was in inverse proportional to the yield stress.

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.11a
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• pp.105-105
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• 1998

• Journal of the Korean Ceramic Society
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• v.44 no.3 s.298
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• pp.157-161
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• 2007

Line width under $100\;{\mu}m$ with good resolution is difficult to achieve using conventional thick-film process utilizing screen printing method. However combined with lithography technology finer line and space for miniaturization and highly integrated package is achievable. In this study, photosensitive Ag paste of optimum formulation used for thick film lithography technology was fabricated by various Ag powder, glass powder and additives. As the result, line width of $30\;{\mu}m$ with good definition and reduced mismatch during co-firing with LTCC substrate was acquired. Formulated Ag paste was used to pattern embedded fine line inductor with over 90% yield.

• Journal of the Korean Ceramic Society
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• v.45 no.6
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• pp.336-344
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• 2008

Rheological properties of cement pastes containing blast furnace slag (BFS: 3,900, $7,910\;cm^2/g$) or fly ash powder (FA: 4,120, $8,100\;cm^2/g$) according to the ratio of water/binder (W/B) and the dosage of polycarboxylate type superplasticizer (PC) were investigated by a mini slump and a coaxial cylinder viscometer. In this experiment, the ratio of replacing OPC with BFS or FA was 30 wt%, the W/B was from 30 to 70 wt%. As a result, the fluidity of cement paste containing BFS or FA was improved with increasing W/B and the dosage of PC. BFS or FA replaced cement paste with W/B 70% and PC 0.3% showed the highest fluidity. The segregation range of cement paste was occurred below $10\;d/cm^2$ of the yield stress and below 50 cPs of the plastic viscosity by the coaxial cylinder viscometer. And also it was formed that the plastic viscosity and the yield stress of FA replaced cement paste were higher than them of BFS replaced cement paste.

• Journal of Powder Materials
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• v.24 no.5
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• pp.395-399
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• 2017

Solder paste is widely used as a conductive adhesive in the electronics industry. In this paper, nano and microsized mixed lead-free solder powder (Sn-Ag-Cu) is used to manufacture solder paste. The purpose of this paper is to improve the storage stability using different types of solvents that are used in fabricating the solder paste. If a solvent of sole acetate is used, the nano sized solder powder and organic acid react and form a Sn-Ag-Cu malonate. These formed malonates create fatty acid soaps. The fatty acid soaps absorb the solvents and while the viscosity of the solder paste rises, the storage stability and reliability decrease. When ethylene glycol, a dihydric alcohol, is used the fatty acid soaps and ethylene glycol react, preventing the further creation of the fatty acid soaps. The prevention of gelation results in an improvement in the solder paste storage ability.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.10
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• pp.844-849
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• 2011

Two kind of Ag-pastes were prepared for integrating the bulk Si solar cell. One is the Ag-paste with Pb-based glass frit and the other is that with Bi-based glass frit. The pastes were the mixture of 84 wt% Ag, 2 wt% glass frit, 11 wt% solvent of buthyl cabitol acetate, and 2 wt% additives. After fabricating the Ag-pastes, they was coated on a $SiN_x$/n+/p- stacks of a commercial mono-Si solar cell. The solar cell efficiency was 17.6% in the case of the Pb-based Ag-paste. However that was 16.2% in the solar cell integrated with the Bi-based Ag-paste. The lower performance in Bi-based Ag-paste was caused by the higher series resistance and the lower shunt resistance in comparison with the Pb-based Ag-paste.

• The Korean Journal of Community Living Science
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• v.22 no.4
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• pp.573-578
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• 2011

This research was conducted to enhance the value of low quality sweet persimmon by processing paste by combining low quality sweet persimmon and red-bean. In order to make sweet persimmon paste containing red-bean, the following procedures were executed : 1) the sweet persimmon was cleaned by water 2) the fruit stalk was removed 3) it was peeled, sliced, pitted and crushed 4) steamed and peeled red-bean paste was mixed 5) sweetening materials(starch syrup, sugar and dextrin) and salt were mixed 6) boiled and stored in refrigerator. Sweet persimmon was peeled, stem and seed was removed to make the paste. When mixing sweet persimmon paste and red-bean paste in the ratio of 6 : 4, sensory point of taste and overall desirability were higher than mixing in 5 : 5 and 4 : 6 but texture was lower. The sweet persimmon paste containing red-bean was softened and the sugar content was increased from 41.4$^{\circ}$Brix to 53.1$^{\circ}$Brix when 10% dextrin was added. The overall sensory evaluation was higher in sweet persimmon paste containing red-bean than commercial red-bean paste when 10% dextrin was added. The overall desirability also shown a significant difference between them. Even though findings were statistically insignificant, sweet persimmon powder with red-bean paste increased in texture and overall desirability compared with commercial red-beans paste. Sweet persimmon powder paste containing red-bean significantly decreased in flavor, color, taste and overall desirability compared with sweet persimmon paste containing red-bean. As a result of this study, the best combination for the quantity of sub-materials to make sweet persimmon paste was 600g of sweet persimmon, 400g of red-bean, starch syrup 120g, sugar 60g, salt 4g and dextrin 100g.