• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.151-156
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• 2002

Drying shrinkage cracking which may be caused by the relatively large specific surface is a matter of grave concern for latex modified concrete(LMC) overlay and rapid-setting cement latex modified concrete(RSLMC) overlay. LMC and RSLMC were studied for field applications very actively in terms of strength and durability in Korea. However, there were no considerations in drying shrinkage. Therefore, the purpose of this study was to investigate the drying shrinkage properties of LMC and RSLMC with the main experimental variables such as cement types(ordinary portland cement, rapid setting cement), latex contents(0, 5, 10, 15, 20%), W-C ratios, and curing days at a controlled environment of 60% of relative humidity and 2$0^{\circ}C$ of temperature. The drying shrinkage for specimens was measured with a digital dial gauge of Demec. The test results showed that the drying shrinkage of LMC and RSLMC were considerably lower than that of OPC and RSC, respectively. This might be attributed to the interlocking of hydrated cement and aggregates by a film of latex particles, water retention due to hydrophobic, and colloidal properties of the latexes resulting in reduced water evaporation.

• International Journal of Industrial Entomology and Biomaterials
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• v.27 no.1
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• pp.180-184
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• 2013

Recently, silk sericin has attracted the attention of researchers owing to its useful properties as a biomaterial including 1) good wound healing and cell activities, 2) fast gelation character, and 3) high water retention property. In the present study, silk sericin was prepared using different extraction times in hot water and the effect of extraction time on the rheological properties of sericin solutions and gels was examined. It was found that the production yield of sericin increased with extraction time. The shear viscosity of sericin solutions and gels decreased with increasing extraction time due to a decrease in sericin molecular weight. When the sericin solution transformed to a gel, the viscosity increased and the shear thinning behavior was more evident. In addition, the shear stress measurements indicated that the slip between the sericin samples and the measuring plate of the rheometer was increased by the gelation of sericin. The compression strength of sericin gel could be increased remarkably (by more than 100 fold) by preparation using the freezing and thawing method.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.4
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• pp.23-29
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• 1999

The effect of dilute sulfuric acid treatment was examined to improve recyclability of coated brokes. Turbidity , electric conductivity , and cationic demand of the white water from coated broke prepared from an alkaline base paper was determined. Sulfuric acid treatment was found to be effective in dissolving undisintegrated substances such as binders, pigments, and fibers. The properties of papers prepared by adding the broke to pulp stock up to 30% dry weight were examined . With the increase of broke addition, retention, sizing degree and smoothness were improved ; on the other hand, formation uniformness, air permeability and internal bonding strength were decreased. The extent of improvement by broke addition was greater for the surfuric acid-treated broke than the control broke. It was concluded that the use of coated broke should be limited within 10-15% weight of the product for either type of broke.

• Journal of Industrial Technology
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• v.22 no.B
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• pp.109-115
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• 2002

This research was performed to investigate the COD removal efficiency and methane production in slurry-typed swine wastes using UASB(upflow anaerobic sludge blanket)reactor. The USAB reactor was operated from 0.8 through 3.3days of HRT in a range of 3 to 15 kg $TCOD/m^3/day$ of volumetric organic loading rate. The removal rate of TCOD was increased with the increase of the HRT. The removal rate of TCOD at an HRT over 2days, became greater than 68% with the methane contents being from 70 to 80%. Methane production rates were increased from 0.27 to $0.36m^3\;CH_4/kg$ CODrem. as HRTs were increased from 0.8 to 3.3days.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.365-366
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• 2009

Humidity curing of the concrete after placing is significant to ensure the crack resistance, strength, and durability. Generally, there are watering and sheet curing methods as humidity curing methods to the upper part of slab concrete, therefore this study investigates effects of these curing methods to preservation of humidity on the cement mortar.

• International Journal of Human Ecology
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• v.8 no.1
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• pp.1-8
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• 2007

Degradation of cellulose during prolonged exposure in atmospheric conditions has been recognized as one of main problems in preserving cellulose-made products. The purpose of this research was therefore to study effects of borohydride reduction in improving both the color and strength retention of cotton fabrics artificially aged at temperatures ranging from $100^{\circ}C$ to $150^{\circ}C$. Results indicated that the fabrics treated with either sodium or tetramethylammonium borohydrides (TMA) were degraded at rates about one-half that of water-washed cotton. These results were consistent over the temperature range. Calculation of the activation energy (Ea) by different methods showed $Ea\;=\;25.5{\pm}\;1.5\;Kcal$, in keeping with measurements made by others at lower temperatures. The TMA-treatment was effective in minimizing discoloration of the fabrics with pre-baking, but not of the un-prebaked fabrics.

• Journal of the Korean Society of Clothing and Textiles
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• v.24 no.1
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• pp.15-23
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• 2000

Effect of fixation methods on the flame retardant(FR) and performance properties of MDPPA/HMM treated cotton fabrics were studied. Combination of three different fixation methods - premercerization, swelling agent treatment, pad dry cure fixation, and wet fixation - were applied to flame retardant finish of cotton with MDPPA/HMM. As a result, an increase in internal volume of cotton fiber by pre-mercerization and addition of swelling agent, and wet fixation increased %add-on of FR agent improving FR efficiency and wash fastness. Tensile strength of MDPPA/HMM treated cotton fabrics by wet fixation and swelling agent were slightly decreased, but that of premercerized cotton was improved. Wet fixated fabric showed lower bending rigidity and better compressional properties which improved fabric hand. Retention of swelling ability of cotton treated with MDPPA/HMM improved moisture absorption properties.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2005.11a
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• pp.259-263
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• 2005

This study was performed to introduce recently developed Polyvinylamine as a wet-end process improving aids and paper properties improving aids. As a retention and drainage aids, cationicity of Polyvinylamine was a very important factor of BCTMP and ONP stock condition. As a dry tensile strength aids, The hydrogen bond of acrylamide functionality and hydroxyl functionality of the pulp was a very important factor of LBKP stock condition and cationicity of Polyvinylamine was a very important factor of BCTMP and ONP stock condition.

• Fibers and Polymers
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• v.7 no.3
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• pp.235-240
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• 2006

Polyacrylonitrile (PAN) fiber was grafted with casein after alkaline hydrolysis and chlorination reactions of the original fiber. The structures and morphologies of the casein grafted fiber were characterized by Fourier transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), and scanning electron microscope (SEM). Moisture absorption, specific electric resistance, water retention value, and mechanical properties were also investigated. The results showed that casein was grafted onto the surface of the PAN fiber and the grafted PAN fiber presented better hygroscopicity compared with the untreated fiber. With proper tensile strength, the modified fiber could still meet the requirement for wearing. A mechanism was proposed to explain the deposit of casein on the synthetic acrylic fiber.

• Proceedings of the KACD Conference
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• 2001.05a
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• pp.258-258
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• 2001

Fiber-reinforced materials have highly favorable mechanical properties. and their strength-to-weight ratios are superior to those of most alloys. When compared to metals they offer many other advantages as well. including non-corrosiveness. translucency. good bonding properties. and ease ofrepair. Fiber-reinforced materials can be categorized to pre-impregnated. impregnation required. dental laboratory products. chairside products and prefabricated posts. so it is not suprising that fiber-reinforced composites have potential for use in many applications in dentistry. Fiber-reinforced materials can be utilized in frameworks for crowns. anterior or posterior fixed prostheses. chairs ide tooth replacements. periodontal splints. customized posts. prefabricated posts. orthodontic retention. denture reinforcements and in implants dentistry. To realize the full potential of using fiber-reinforced composite restorations. it is essential that the clinician and laboratory technician understand concepts of tooth preparation and framework design. Also practitioner may appreciate the background information and other details about the materials themselves so that identify the rationale for their use in various clinical situations. select well-suited materials. and carry out related procedures. Understanding the material properties and take many attentions. fiber-reinforced materials will give more esthetic. more easy. more strong and more reliable restorations.ations.