• Journal of the Korea institute for structural maintenance and inspection
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• v.4 no.3
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• pp.177-184
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• 2000

The purpose of this study is to evaluate the performance of a new viscosity modifying admixture for concrete agent. For this purpose, selected test variables were the ratio of water to cement, the ratio of cement to fine aggregate, contents of superplasticizer, contents of viscosity modifying admixture. As a result of this study, it has been found that addition of viscosity modifying admixture to mortar modfies its fluidity and reduces its segregation by increasing the mortar viscosity. And it has been found that a new viscosity modifying admixture do not significantly affect the setting time, air content of mortar.

• Computers and Concrete
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• v.5 no.5
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• pp.475-490
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• 2008

The paper explores the potential of applicability of Genetic programming approach (GP), adopted in this investigation, to model the combined effects of five independent variables to predict the mini-slump, the plate cohesion meter, the induced bleeding test, the J-fiber penetration value, and the compressive strength at 7 and 28 days of self-compacting slurry infiltrated fiber concrete (SIFCON). The variables investigated were the proportions of limestone powder (LSP) and sand, the dosage rates of superplasticiser (SP) and viscosity modifying agent (VMA), and water-to-binder ratio (W/B). Twenty eight mixtures were made with 10-50% LSP as replacement of cement, 0.02-0.06% VMA by mass of cement, 0.6-1.2% SP and 50-150% sand (% mass of binder) and 0.42-0.48 W/B. The proposed genetic models of the self-compacting SIFCON offer useful modelling approach regarding the mix optimisation in predicting the fluidity, the cohesion, the bleeding, the penetration, and the compressive strength.

• Journal of the Korean Dietetic Association
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• v.30 no.1
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• pp.11-28
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• 2024

This study aimed to establish the optimal amount of thickening agent for the appropriate viscosity in soups and beverages, which are part of the dysphagia diet. The soups were bean sprout soup and soybean paste soup; the beverages were orange juice, regular milk, and low-fat milk; the thickening agent was one type of xanthan gum product. After adding the thickening agents (from 1 g to 5 g per 200 mL of the test food), syringe tests were conducted over time (5, 10 and 15 minutes) to verify the effects of the amount of thickening agent added per sample and the time between addition and achieving the resulting viscosity, and to establish the optimal addition conditions to reach IDDSI levels 1, 2, and 3 of the dysphagia diet. Water (based on 200 mL) was used as the standard control. These results provide a useful basis for customized diets based on the patient's dysphagia severity. On the other hand, this study is limited by including only liquid foods in the dysphagia diet and one type of xanthan gum-based thickening agent. Therefore, it is necessary to conduct continuous research, based on the study results, to modify the viscosity of the dysphagia diet using various thickening agents and foods and prevent nutritional deficiencies by managing the diet according to the patient's swallowing ability.

• Journal of the Korean GEO-environmental Society
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• v.23 no.11
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• pp.5-11
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• 2022

The objective of this study is to evaluate the mechanical properties of high-flowable retaining wall material (RWM) incorporated with ground granulated blast-furnace slag (SG) and steel fiber (SF) based on a comparison with those of ordinary portland cement (OPC). To produce the specimens of RWM, some chemical agents such as superplasticizer (SP), air-entrained agent (AEA) and viscosity modifying agent (VMA) are added in the fresh RWM. The compressive, split tensile and flexural strength measurements were performed on the hardened RWM specimens. Additionally, surface electric resistivity and absorption tests according to ASTM standards were carried out at predetermined periods after water curing. It was found that the mechanical properties of slag cement concrete (SGC) RWM mix are better than those ordinary portland cement concrete (OPC) RWM mix. The effect of SF is remarkable to improve the mechanical properties of RWM mixes. It is noted that the usage of SG shows a beneficial effect to resist water penetration as well as long-term strength development of RWM mixes.

• Journal of the Korean GEO-environmental Society
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• v.24 no.6
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• pp.13-20
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• 2023

This paper is aimed to evaluate the mechanical properties and durability of high-flowable retaining wall material (RWM) with different levels of steel fiber (SF) content. To produce the specimens of RWM, some chemical agents such as superplasticizer (SP), air-entrained agent (AEA) and viscosity modifying agent (VMA) were added in the fresh RWM. The compressive and split tensile strength measurements were performed on the hardened RWM specimens at the predetermined periods. Additionally, surface electric resistivity and absorption tests according to ASTM standards were carried out to examine mechanical properties of RWM mixes. The durable performances such as chloride ions penetrability and freezing-thawing resistance of RWM mixes were experimentally investigated. As resutls, it was found that the performance of RWM mix with SF were much better than that without SF, especially at the 2% addition of SF. Thus, it is noted that the proper addition of SF in the RWM mix may have a beneficial effect to improve mechanical properties and durability of RWM mixes.

• Elastomers and Composites
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• v.25 no.4
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• pp.280-290
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• 1990

The effect of surface treatment of kaolinite with silane coupling agent on the reinforcement of SBR was investigated. The possibility of the practical use of kaolinite as an organic filler was also scrutinized and it was found that the reinforcement of SBR was improved by modifying surface of the cheap inactive inorganic filler with organic silane coupling agents. 3-Chloropropyltrimethoxysilane(C-series), 3-mercaptopropyltrimethoxysilane(M-series) and 3-aminopropyltriethoxysilane(A-series) were used as coupling agents. To test the material properties of vulcanized and unvulcanized SBR, Mooney viscosity, modulus, elongation and fractured surface measurements by SEM were carried out by changing the amount of silane coupling agents. Torqe of the unvulcanized SBR following the measurement of the degree of vulcanization was to be increased as the amount of silane was increasing, and Mooney viscosity of M-series and A-series was also increased.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.4
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• pp.618-624
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• 1989

Ultrasonically induced bubble formation in thermoplastic matrix was investigated experimentally and theoretically. polystyrene was saturated with nitrogen under the pressure of 0.2 to 3.45 MPa in a pressure chamber, followed by pressure release and ultrasonic bubble nucleation. Zinc stearate was added to polystyrene as the nucleating agent to induce heterogeneous nucleation. Various mixture of low density polyethylene and polyethylene wax was also saturated with the gas. The foamed specimens with or without ultrasonically induced bubble nucleation was modeled by modifying the classical nucleation theory. The rate of ultrasonic nucleation was predicted for homogeneous and heterogeneous nucleation at a conical cavity. This study showed that the heterogeneous and heterogeneous nucleation at a conical cavity. This study showed that the heterogeneous nucleation must be employed for ultrasonic production of bubbles in a viscous fluid and the homogeneous nucleation for ultrasonic production of bubbles in a low viscosity fluid.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.1
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• pp.24-31
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• 2024

Mortar has been applied in most previous studies on 3D concrete printing. In such cases, however, the economic efficient cannot help decreasing due to higher binder contents and larger amount of fine aggregates. In order to enhance the applicability of 3D printing technology to construction industry, therefore, 3D concrete printing technology utilizing coarse aggregates needs to be developed further. This study aims at proposing the mix design process of concrete containing coarse aggregates for 3D printing. Based on extensive literature review and experimental studies, the mix proportion suitable for 3D printing has been derived, and the extrudability of concrete with coarse aggregates has been verified through 3D printing tests. The primary variable of the extrudability tests was the contents of viscosity modifying agent (VMA), and the extrudability was quantitatively evaluated by measuring dimensions, distribution of aggregates, and surface quality of 3D-printed filaments. The test results showed that the dimensional suitability and surface quality were improved as the VMA contents were larger, and the coarse aggregates were evenly distributed in the section of filament regardless of the VMA contents. Based on the test results, the mix design process for concrete containing coarse aggregates for 3D printing has been proposed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.546-546
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• 2008

Copper (Cu) Chemical mechanical polishing (CMP) has been an essential process for Cu wifing of DRAM and NAND flash memory beyond 45nm. Copper has been employed as ideal material for interconnect and metal line due to the low resistivity and high resistant to electro-migration. Damascene process is currently used in conjunction with CMP in the fabrication of multi-level copper interconnects for advanced logic and memory devices. Cu CMP involves removal of material by the combination of chemical and mechanical action. Chemicals in slurry aid in material removal by modifying the surface film while abrasion between the particles, pad, and the modified film facilitates mechanical removal. In our research, we emphasized on the role of chemical effect of slurry on Cu CMP, especially on the effect of amine functional group on removal rate selectivity between Cu and Tantalum-nitride (TaN) film. We investigated the two different kinds of complexing agent both with amine functional group. On the one hand, Polyacrylamide as a polymer affected the stability of abrasive, viscosity of slurry and the corrosion current of copper film especially at high concentration. At higher concentration, the aggregation of abrasive particles was suppressed by the steric effect of PAM, thus showed higher fraction of small particle distribution. It also showed a fluctuation behavior of the viscosity of slurry at high shear rate due to transformation of polymer chain. Also, because of forming thick passivation layer on the surface of Cu film, the diffusion of oxidant to the Cu surface was inhibited; therefore, the corrosion current with 0.7wt% PAM was smaller than that without PAM. the polishing rate of Cu film slightly increased up to 0.3wt%, then decreased with increasing of PAM concentration. On the contrary, the polishing rate of TaN film was strongly suppressed and saturated with increasing of PAM concentration at 0.3wt%. We also studied the electrostatic interaction between abrasive particle and Cu/TaN film with different PAM concentration. On the other hand, amino-methyl-propanol (AMP) as a single molecule does not affect the stability, rheological and corrosion behavior of the slurry as the polymer PAM. The polishing behavior of TaN film and selectivity with AMP appeared the similar trend to the slurry with PAM. The polishing behavior of Cu film with AMP, however, was quite different with that of PAM. We assume this difference was originated from different compactness of surface passivation layer on the Cu film under the same concentration due to the different molecular weight of PAM and AMP.