• Advances in environmental research
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• v.6 no.3
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• pp.159-171
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• 2017

A successful oil well drilling depends largely on a good mud Program. During drilling, mud provides sufficient hydrostatic pressure, removes drill cuttings and cools drill bits. Mud additives are always required to provide sufficient hydrostatic pressure to ensure borehole stability. Barium Sulphate ($BaSO_4$) also known as barite is the prevalent weighting material but there is needed to develop local materials to augment the use of Barite. The present search is concerned on the early Carboniferous succession exposed in Um Bogma Formation, west central Sinai, Egypt as a new weighting agent in drilling fluids. The increases in the cost of drilling fluids and a shortage of using barite have introduced the locale dolomite as alternative weighting materials. The rheological properties of mud drilling samples weighted by local dolomite samples are being examined and investigated to know its potential to be used as a weighting material in drilling mud. Two mud samples were prepared which comprised of fresh water, caustic soda, bentonite and the weighting material. The weighting materials are added to achieve the required density. The first sample: Water-based mud with commercial barite of density between 10.00 lb/gm and 18.00 lb/gm. The second sample: Water-based mud with dolomite of density between 10.00 lb/gm and 18.00 lb/gm. These samples were analyzed and the density, rheological properties, aging of barite and dolomite and solid contents were investigated. At 10.00 lb/gm, the yield point of dolomite was $20.00lb/100ft^2$ and barite $22.00lb/100ft^2$ while the 10 second gel strength of dolomite was $30.00lb/100ft^2$ and $22.00lb/100ft^2$ for barite. Similarly, little difference was observed in plastic and apparent viscosities. At 10.00 lb/gm, the plastic and apparent viscosities of dolomite were 8.00 cp and 20.00 cp while barite was 8.00 cp and 24.00 cp. The result show that dolomite mud sample gave a little higher yield point and gel strength than barite mud sample. Therefore, dolomite has the potential to be used as weighting material in drilling mud in place of barite thereby enhancing the local content initiative of the government. When dolomite is sourced locally and used it will reduce overall mud and drilling costs.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.1
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• pp.31-40
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• 2009

The rheologic properties of elastic impression materials is a very important role as taking high accuracy impression. But, the studies that are focused on the rheologic properties of Korean elastic impression materials are not sufficient. The purpose of this study is to help clinical high accuracy impression taking by testing rheologic properties of elastic impression material that is made by Korea and other countries. Six type III elastic impression materials are tested. Subjects are 2 Korean polyvinylsiloxane(PVS), 2 imported PVS, 1 polyether, and 1 polysulfide. HAAKE RheoStress $1^{(R)}$(Thermo Electron Co. Germany)is used in measuring. HAAKE RheoStress $1^{(R)}$ is plate to plate type rheometer. All subjects is tested 3 times and measuring time is 900 seconds. We measured G′ and loss tangent after mixing. All elastic impression materials had a sigmoid shape on increasing G′ by time and decreasing loss tangent after setting, maximum G' is appeared highest in polyether, and lowest in polysulfide. Initial loss tangent is highest in polyether, and is lowest in Koreans PVS. Significant difference is showed in initial loss tangent between Korean PVS and imported PVS.

• Applied Biological Chemistry
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• v.48 no.3
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• pp.273-279
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• 2005

To develop cosmetics using Jindalae flowers (Rhododendron mucronulatum), the surface tensions of extracts were measured and the properties and stability of cream with extracts were investigated. The surface tension of 0.1% ethanol extract was 30.42 mN/m and that of distilled water was 72.2 mN/m. The surface tension of cream with 0.1% ethanol extract was similar to that of sample cream and the measured pH were weakly alkalic. The surface tension of 1% ethanol extract was the lowest value of 24.98 mN/m, the measured pH of cream with 1% ethanol extract was weakly acidic and the particle size of cream was stable. According to an oscillatory test, linear viscoelastic region was extended by adding of 1% water extract and 1% ethanol extract to cream, indicating that the cream had greater enhanced resistance for preserving inner structure as compared to outside stress.　Besides, as a result of the diminished loss angle of ethanol extract cream, the elasticity of cream was increased more than that of sample cream and cream with 0.1% ethanol extract. In contrast, in the case of the increased loss angle of water extract cream, the viscosity of cream was increased. In conclusion, Rhododendron mucronulatum can be deliberated as a cosmetic material because 0.1% water and ethanol extracts showed efficacious physiological activities and cream with 1% extracts could extend linear viscoelastic region.

• Advances in concrete construction
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• v.9 no.6
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• pp.547-556
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• 2020

This study aimed to develop reference materials (RMs) that are chemically stable and can simulate the flow characteristics of cement paste. To this end, the candidate components of RMs were selected considering the currently required properties of RMs. Limestone, slag, silica, and kaolin were selected as substitutes for cement, while glycerol and corn syrup were selected as matrix fluids. Moreover, distilled water was used for mixing. To select the combinations of materials that meet all the required properties of RMs, flow characteristics were first analyzed. The results revealed that silica and kaolin exhibited bilateral nonlinearity. When an analysis was conducted over time, slag exhibited chemical reactions, including strength development. Moreover, fungi were observed in all mixtures with corn syrup. On the other hand, the combination of limestone, glycerol, and water exhibited a performance that met all the required properties of RMs. Thus, limestone, glycerol, and water were selected as the components of the RMs. When the influence of each component of the RMs on flow characteristics was analyzed, it was found that limestone affects the yield value, while the ratio of water and glycerol affects the plastic viscosity. Based on this, it was possible to select the mixing ratios for the RMs that can simulate the flow characteristics of cement paste under each mixing ratio. This relationship was established as an equation, which was verified under various mixing ratios. Finally, when the flow characteristics were analyzed under various temperature conditions, cement paste and the RMs exhibited similar tendencies in terms of flow characteristics. This indicated that the combinations of the selected materials could be used as RMs that can simulate the flow characteristics of cement paste with constant quality under various mixing ratio conditions and construction environment conditions.

• Journal of the Korean Ceramic Society
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• v.38 no.9
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• pp.860-865
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• 2001

After manufacturing 2mol% CdO substitute $0.05Pb(Mn_{1/3}Sb_{2/3})O_3-0.95Pb(Zr_{0.52}Ti_{0.48})O_3$ piezoelectric ceramics powder as starting material, to manufacture green sheets using Doctor Blade method. The optimum composition of slurry was studied. Moreover, the sintering properties and the dielectric and piezoelectric properties with variation a thickness of the manufactured sheets were investigated. The optimum of slurry was investigated by the rheology with addition of additives, the sintering condition was decided by TGA. And the properties of sheet were investigated through SEM. XRD. The optimum of slurry was the stablest at dispersant 3.0 wt% to solid loading 30vol%. After, at addition of binder/plasticizer(0.75/0.25) 3.0wt%, viscosity was 7.55Pa${\cdot}$s. The dielectric and piezoelectric properties of the sheet were increased a little with the increasing of sintering temperature but were not variable with variation of sheet thickness.

• Journal of the East Asian Society of Dietary Life
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• v.14 no.4
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• pp.370-378
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• 2004

The purpose of this study was to investigate the effect of added nutriprotein and rice powder as a plasticizer on physicohemical property, texture property of Backsulgi. In the physicochemical property, the content of proximate composition of nutriprotein was measured as 6.1% of moisture, 3.6% of carbohydrate, 84.3% of crude protein, 0.6% of crude lipid, 5.4% of ash. The raw material of rice powder was measured as 9.6% of moisture, 83.7% of carbohydrate, 6.0% of crude protein, 0.4% of crude lipid, 0.3% of ash. Swelling power and pore ratio of the control were 78.53% and 72.42%, and tended to increase as the amounts of nutriprotein and plastic rice powder increased. Aging by Avrami eguation retarded in Backsulgi added 10% plastic rice powder than rice powder Backsulgi. All the samples added 2, 4, 6, and 8% nutriprotein at the temperatures of 20 were more effective than others on aging. In texture properties, cohesiveness and springiness were not significantly changed by adding nutriprotein and not significantly changed during the storage period in all samples. Hardness and gumminess decreased by adding 2∼8% nutriprotein and increased during the storage period in all samples. Springiness and gumminess decreased by adding 40% plastic rice powder and increased during the storage period in all sample. Cohesiveness and hardness decreased by the increase of plastic rice powder. The texture characteristics by rheometer showed that Backsulgi with nutriprotein and plastic rice powder exhibited lower in hardness than the control, indicating that nutriprotein and plastic rice powder were effective in retarding retrogradation, which is better when storage time became longer.

• Journal of the Korea Institute of Building Construction
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• v.2 no.4
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• pp.145-152
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• 2002

High fluid concrete unlike OPC concrete is made with various material, and the phase of fresh concrete is considerably different. In order to understand fluidity phase and mix properties of high fluid concrete, concrete is required to access as suspension structure which consists of aggregate and paste. The focus of this paper is to analyze the test results and quantify the effect of mix proportions of mortar and fineness modulus of sand on the properties of fresh mortar. The effect of water-binder ratio. sand-binder ration. contents of ggbs (by mass of total cementitious materials). and various contents of water reducing agent on the yield stress and plastic viscosity of the mix is studied. Based on the experimental results, the fellowing conclusions can be drawn: (1) The mixing time needed for high fluid mortar was approximately two times more than that of ordinary portland mortar. (2) The fluidity phase of mortar could be explained by yield stress of mix and the fluidity of mortar. (3) As the content of ggbs increased, yield stress of mortar was decreased and plastic viscosity of it was increased. (4) For the high fluid mortar, it was appeared that sand-binder ratio should be below 1.5.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.135-140
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• 2021

In this study, the concrete aggregate shape features were extracted from the cross-section of a normal concrete strength cylinder, and the compressive strength of the cylinder was predicted using artificial neural networks and image processing technology. The distance-angle features of aggregates, along with general aggregate shape features such as area, perimeter, major/minor axis lengths, etc., were numerically expressed and utilized for the compressive strength prediction. The results showed that compressive strength can be predicted using only the aggregate shape features of the cross-section without using major variables. The artificial neural network algorithm was able to predict concrete compressive strength within a range of 4.43% relative error between the predicted strength and test results. This experimental study indicates that various material properties such as rheology, and tensile strength of concrete can be predicted by utilizing aggregate shape features.

• Journal of the Korean Society for Railway
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• v.18 no.6
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• pp.543-551
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• 2015

Quick-hardening track (QHT) is a construction method which is used to change from old ballast track to concrete track. Sufficient time for construction is important, as the construction should be done during operational breaks at night. Most of the time is spent on exchanging the ballast layer. If it is possible to apply the ballast non-exchange type of quick-hardening track, it would be more effective to reduce the construction time and costs. In this paper, pouring materials with high permeability are suggested and a construction method involving a layer separation pouring process considering the void condition is introduced in order to develop ballast non-exchange type of QHT. The separate pouring method can secure the required strength because optimized materials are poured into the upper layer and the lower layer for each void ratio condition. To ensure this process, a rheology analysis was conducted on the design of the pouring materials according to aggregate size, the aggregate distribution, the void ratio, the void size, the tortuosity and the permeability. A polymer series was used as the pouring material of the lower layer to secure the void filling capacity and for adhesion to the fine-grained layer. In addition, magnesium-phosphate ceramic (MPC) was used as the pouring material of the upper layer to secure the void-filling capacity and for adhesion of the coarse-grained layer. As a result of a mechanics test of the materials, satisfactory performance corresponding to existing quick-hardening track was noted.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.4
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• pp.73-80
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• 2022

This study evaluated changes in fluidity and rheological properties over time for 3D printed composite materials, and evaluated compressive strength and splitting tensile strength properties for laminated and molded specimens. The composite material for 3D printing starts to change rapidly after 30 minutes of extrusion, and the viscosity of the material tends to be maintained up to 90 minutes, but it was confirmed that construction within 60 minutes after mixing is effective. The compressive strength of the laminated test specimen showed equivalent or better performance at all ages compared to the molded test specimen. In the stress-strain curve of the laminated specimen, the initial slope was similar to that of the molded specimen, but the descending slope was on average 1.9 times higher than that of the molded specimen, indicating relatively brittle behavior. The splitting tensile strength of the P-V laminated specimen was about 6% lower than that of the molded specimen. It is judged that this is because the interfacial adhesion force against the vertical load is affected by the pattern direction of the laminated test specimen.