• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.346-349
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• 2006

Superstructure of reinforced concrete bridges are shortened or elongated due to creep, drying shrinkage, temperature and so on. Most of bridge superstructures are free to shortening and elongation without constraint and stresses will not be induced by creep, drying shrinkage and temperature. But if bridge superstructure are constraint due to wrong setting and functional defects of bridge bearing, very large constraint forces can be induced. In this study, PSCI-Beam by tilt-constructed with constraint and deviation of bearings are presented and the effects of time-dependent constraint stress and temperature loads are investigated.

• Textile Coloration and Finishing
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• v.22 no.1
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• pp.61-70
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• 2010

This effects of drawing conditions on the physical properties of the drawn worsted yarns were investigated. The drawn worsted yarns were made on the yarn drawing system with various drawing conditions such as concentration of reducing agent, draw ratio, setting time of drawn yarn and concentration of oxidizing agent. The dry and wet shrinkage, irregularity(CV%), thin and thick part, hairiness and abrasion resistance of these various specimens were measured and discussed in terms of various drawing conditions.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.188-189
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• 2019

In this study, the characteristics of single-component and other sealant were analyzed to provide repair methods and effective utilization of sealant due to crack generation. Humidity studies have shown that acrylic silicone is effective in many areas of fluidity and temperature change, and that polysulfide-silicon is most effective in resistance to linear expansion coefficient and external pressure. Therefore, the difference between drying shrinkage and thermal expansion coefficient between various building materials and sealant, as well as the use of sealant, is analyzed, and construction methods derived accordingly, and prevention of defects are considered to be part of the construction project.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.318-320
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• 2013

The spherical bead manufactured by rapidly cooling process shows high density of 3.64g/㎤, high unit volume weight of 2.6kg/l, and high solid volume of 71%. When it applies to the grouter, it is possible to obtain even high fluidity with only a small amount. This study, focusing the grouter using a rapidly-cooled electric arc furnace oxidizing slag(RC-EAFS), deals with the properties of flow and setting time in fresh state, compressive strength and length variation at 1, 3, 7 and 28 curing day in hardened state. As the results, even though the grouter with RC-EAFS shows comparative low strength, it will be possible to development the competitive product due to the properties of increasing flow and low cost.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.483-488
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• 2016

The present study proposes an economical embedded ring-sensor that can measure a strain behavior of cement paste and mortar in early age. Using the proposed ring-sensor, the experimental method is proposed that can measure the setting time of the cement paste and mortar conveniently. The experimental study has been conducted using the mixtures of which W/C are 0.30, 0.35, 0.40, and 0.45. From the test result, the setting times measured by convectional test methods such as vicat method and penetration resistance method are compared with the setting time proposed by this study. The result reveals that the proposed ring-sensor can effectively measure the early age behavior so that can evaluate the time when the contraction starts. In addition, the contraction starting time can be regarded as a rational setting time, which is similar to the initial setting of convectional test methods.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.660-663
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• 2004

This paper investigate the qualities variety of concrete using recycling water under various kinds and contents of saccaric based stabilizing agent(SSA). Fluidity had little changes with the kinds and contents of SSA. Air contents of concrete with recycled water only shows the tendency. With an increase in SSA contents, air content recovered. For bleeding properties, bleeding shows to be decreased with an increase in SSA contents. The use of recycled water accelerated the setting time. However, with an increase in SSA, setting time showed the similar level of plain concrete. SSA (Btype) had better performance in enhancing compressive strength owing to loss of air content. Although the use of recycled water increased the drying shrinkage compared with that of plain concrete, it tended to decrease with an increase in SSA.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.651-654
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• 2005

Fast-setting cement is usually used for emergency repair construction of roads, bridges, buildings and so on. In this study, we tried to develop fast-setting ultra early strength mortar for prepacked concrete and evaluated the properties of fresh and hardened concrete with it. The flowability of the mortar was high enough to be easily poured into coarse aggregates. It showed high early strength development which can make it possible to use newly constructed structures within $3\~4$ hours regardless of curing conditions such as curing temperature and curing environment. And it also showed good resistance to drying shrinkage and chemical attack.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.369-372
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• 2005

This study is about physical properties of concrete with changing displacement ratio of calcium sulfa aluminates(CSA) type admixture. Firstly, test shows that as displacement ratio of CSA increases and setting properties changes, fluidity and air contents decreases. In water to binder ratio 35$\%$ and 45$\%$, concrete using the cement replacing CSA 4$\%$ by volume shows that bleeding decreases 94.7$\%$ and 74.3$\%$ respectively, compared with plain concrete. In addition, setting time was promoted around 3 to 6 hour and 1 to 4 hour respectively. For harden concrete, increase of displacement ratio caused tendency of higher compressive strength as OPC has at early age. Replacing higher CSA admixture led to reduce of drying shrinkage.

• Journal of Technologic Dentistry
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• v.9 no.1
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• pp.79-88
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• 1987

According as the density of prosthetic by casting among the prosthetic restorations is increasing now, the definition and the bounds as to the casting, the method of making the right casting and the establishment of concepts about a minute report and so on, the establishment of the basic principles like those are unavoidable, and then the casting shrinkage must be compensated by setting expansion thermal expansion. Hygroscopic expansion in making the good casting types as we demonstrated that already asbestos lining. We confirmed the fact that the considerable concern about the surface tension and the gas inspiration? Is necessary in making better the casting.

• The Korean Journal of Applied Statistics
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• v.7 no.1
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• pp.75-82
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• 1994

It is known that collinearity among the explanatory variables in generalized linear models inflates the variance of maximum likelihood estimators. A ridge-type estimator is presented using penalized likelihood. A method for choosing a shrinkage parameter is discussed and this method is based on a prediction-oriented criterion, which is Mallow's $C_L$ statistic in a linear regression setting.