• Proceedings of the KACD Conference
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• 2001.11a
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• pp.579-579
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• 2001

One of the most important factors for the clinical success of adhesive posterior restorations is marginal adaptation. This property is very closely related to mechanical properties and to the shrinkage behavior of composite materials. Most of modem composite materials are light-cured. This is why the first part of this lecture will be confined to our recent research on light curing, such as plasma polymerization, LED polymerization and the power of modem halogen lamps. In the second part of the lecture the shrinkage properties such as dimensional shrinkage and shrinkage forces of different light curing materials and during different curing procedures will be discussed. Finally, in the third part of the lecture, marginal adaptation before and after loading in different cavity classes and by using different restorative techniques and curing procedures will be presented. Data will also be given on wear resistance, abrasiveness against opposing cusps and postcuring of composite materials.(omitted)

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.98-99
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• 2017

This study investigated the drying shrinkage and compressive strength properties of mortar by the blaine of ferro-nickel slag powder to estimate the applicability of ferro-nickel slag powder for cement replacement materials. As a test result, the blaine of ferro-nickel slag powder increased, the compressive strength increased and the shrinkage rate decreased.

• Journal of the Korea Institute of Building Construction
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• v.6 no.1 s.19
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• pp.73-77
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• 2006

Drying Shrinkage has much complexity as it has relations with both internal elements of concrete and external factors. Therefore, experiments on Concrete Drying Shrinkage are carried out in this study under simplified circumstances applying temperature & Humidity test chamber which enables constant temperature and humidify. Comparative analyses have been made respectively according to the consequences aiming at modelling for prediction of Concrete Drying Shrinkage and making out measures to reduce it. As a result Strain Rate of Drying Shrinkage of concrete was measured to increase by average $10{\times}10^{-5}$ in proportion to additional 4% increase in fine aggregate ratio, when water/cement ratio constant. Strain Rate of Drying Shrinkage in pit sand concrete increased 20% higher than measured when in river sand under the condition of 90-day material age. 6. Strain Rate of Drying Shrinkage in sea sand concrete increased $10%{\sim}15%$ higher than measured when in river sand. The results of prediction of Rate of Drying Shrinkage by Response Surface Analysis are as fellows. The coefficient of correlation of Drying Shrinkage in concrete was over 90%.

• Journal of the Korea Institute of Building Construction
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• v.22 no.1
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• pp.45-55
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• 2022

Ultra-low shrinkage concrete is very effective for securing the quality and appearance of a concrete structure because it can control the drying shrinkage cracks of the concrete structure to within a certain limit. In this study, with the purpose of commercializing ultra-low shrinkage concrete, the optimal amount of expansive agent and shrinkage reducing agent was determined through a lab test, and a concrete wall mock-up test was conducted to examine the shrinkage properties and crack control effects of ultra-low shrinkage concrete. As a result, it was confirmed that there was little drying shrinkage deformation in the wall specimen, and furthermore that no cracks were generated.

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.103.1-103.1
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• 2007

• Journal of the Korean Home Economics Association
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• v.17 no.4
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• pp.15-22
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• 1979

This paper was studied changes of physical properties of Lining fabrics by washing and difference between dry method. I experimented four kinds of Lining fabrics for the sample . The analysis was performed by correlation coefficient analysis and significance tested between correlation coefficients. The results are summarized as follows : 1) Increasing rate of shrinkage tends to call high density and weight. 2) Rayon fabrics is shown the most high rate of shrinkage and decreasing strength by increasing washing times. 3) Drip dry makes little change of physical properties. 4) Polyester fabrics is little by washing times and dry method.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.150-155
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• 1993

The use of polypropylene fibers in concrete has been widely advertised by the fiber manufacturers. However, the behavior of concrete containing plastic fibers has not been fully understood. The effects of fiber on concrete have been forcused on shrinkage crack control mainly from field observation, and the mechanism and the side effect of fiber such as workability reduction have been neglicted. In this paper, the effect of fiber on workability and shrinkage properties have been studied. The addition of fiber significantly reduce workability and requires additional water to maintain the workability, which causes adversal effects on concrete properties.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.1
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• pp.181-188
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• 2005

Generally, high performance concrete has characteristics such as low water-cementitous material ratio, lots of unit binder powder, thus the drying shrinkage and autogenous shrinkage are tend to be increased. The purpose of this study is to investigate the effect of the glyclos based shrinkage reducing agent on the drying shrinkage and autogenous shrinkage of high performance concrete with 30% of water-cemetitious material ratio as a study to develop the technology to reduce the concrete shrinkage. Test results show that the drying and autogenous shrinkage of high performance concrete are reduced by about 20~35% at the mixing ratio of shrinkage reducing agent of 0.5%, and 1.0%, compared with plain concrete. Therefore, it analyze that the using of shrinkage reducing agent is effective to reduce the drying shrinkage and autogenous shrinkage of high performance concrete.

• Journal of Adhesion and Interface
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• v.14 no.4
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• pp.192-196
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• 2013

In this study, a series of bi-axially oriented films based on homo polypropylene (PP) and hydrocarbon resin (HCR) modified PP were prepared to investigate their mechanical properties, optical properties, permeability to gases and water vapors and shrinkage ratio. Hydrogenated dicyclopentadiene (DCPD) resin and hydrogenated C9 resin were used as HCR in this study. Bi-axially oriented polypropylene (BOPP) films made with PP/HCR blends showed better mechanical properties (higher Young's modulus), better optical properties (lower haze), lower permeability to gases and water vapors and increased shrinkage ratio than BOPP films made with homo-PP. Hydrogenated DCPD resin and hydrogenated C9 resin showed similar contribution to the improvement in mechanical properties and optical properties of BOPP films, but there are a differences in permeability to gases and water vapors and shrinkage ratio.

• Journal of the Korea Concrete Institute
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• v.14 no.1
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• pp.76-82
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• 2002

The rapid-set cement concrete causes high hydration temperature and nay result in a high drying shrinkage and shrinkage-induced cracking. This problem may be fixed by incorporating polypropylene fibers in rapid-set cement concrete, because of increased toughness, resistance to impact, corrosion, fatigue, and durability. A series of concrete drving shrinkage tests was peformed in order to investigate the shrinkage properties of polypropylene fiber reinforced concrete with experimental variables such as concrete types, fiber reinforcement, W/C ratio, with and without restraint. Uni-axially restrained bar specimens were used for the restrained shrinkage tests. The results were as follows; The dry shrinkage of rapid-set cement concrete was much lessor than that oi OPC, probably because of smaller weight reduction rate by early hydration and strength development. The constraint and bridging effects caused by polypropylene fibers were great for the rapid-setting cement concrete when compared with that of plain concrete, and this resulted In increased resistance against tensile stress and cracking.