• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.39 no.5
• /
• pp.32-38
• /
• 2007

The purpose of this study is to investigate the cause of fine wrinkles occurred in silky wallpaper and its solution. The characteristics of base papers, wallpapers and adhesives (conventional and modified) were evaluated to find the possibility for the occurrence of fine wrinkles. It was found that the base papers and wallpapers did not cause the occurrence of silky wallpaper. It was concluded that the fine wrinkles in silky wallpaper was caused by the nonuniform distribution of adhesive, the localized shrinkage of adhesive and the breaking the balance between the resistance of wallpaper and shrinkage of adhesive. Three possible solutions for the prevention of the occurrence of fine wrinkles in silky paper were recommended.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.49 no.5
• /
• pp.23-30
• /
• 2007

This research was to evaluate the shrinkage and durability performance of latex modified repair mortar and to improve the service lift of the agricultural concrete structures. The shrinkage characteristics of the repair material creates the delamination of repair materials and existing concrete. It may reduce the service life of structures. Also the reduction of durability performance of the repair materials induces the destruction of the repaired concrete structures at early stage. In this research, plastic and drying shrinkage, thermal expansion coefficient for shrinkage properties, durability performance, permeability, repeated freezing and thawing, and resistance of chemical solution test were performed. Test results showed that the latex modified repair mortar indicated the shrinkage amount which the delamination does not happen, and the latex modified repair mortar appeared excellent long-term durability performance which can increase the service life.

• Computers and Concrete
• /
• v.23 no.5
• /
• pp.329-334
• /
• 2019

Traffic flow capacity of some old road bridges is insufficient due to limited deck width. In such cases bridge deck widening is a common solution. For multi-girder reinforced concrete (RC) bridges it is possible to add steel-concrete composite girders as the new outermost girders. The deck widening may be combined with bridge strengthening thanks to thickening of the existing deck slab. Joint action of the existing and the added parts of such bridge span must be ensured. It refers especially to the horizontal plane at the interface of the existing slab and the added concrete layer as well as to the vertical planes at the external surfaces of the initially outermost girders where the added girders are connected to the existing bridge span. Since the distribution of the added concrete is non-uniform in the span cross-section the structure is particularly sensitive to the added concrete shrinkage. The shrinkage induces shear forces in the aforementioned planes. Widening of a 12 m long RC multi-girder bridge span is numerically analysed to assess the influence of the added concrete shrinkage. The analysis results show that: a) in the vertical plane of the connection of the added and the existing deck slab the longitudinal shear due to the shrinkage of the added concrete is comparable with the effect of live load, b) it is necessary to provide appropriate longitudinal reinforcement in the deck slab over the added girders due to tension induced by the shrinkage of the added concrete.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.793-798
• /
• 2003

The purpose of this study is to investigate the setting properties of polystyrene mortars using waste expanded polystyrene(EPS) solution-based binders. The binders for polystyrene mortars are made by mixing crosslinking agent with waste EPS solutions which prepared by dissolving EPS in styrene. Polystyrene mortars are prepared with various EPS concentrations of EPS solutions and crosslinking agent contents, subjected to a dry curing, and tested for working life, peak exotherm temperature and 10h-length change. From the test results, the working lives of polystyrene mortars are shortened with raising EPS concentration of EPS solution and crosslinking agent content. Low-shrinkage or non-shrinkage of polystyrene mortars should be accomplished by adjusting EPS concentration of EPS solution and crosslinking agent content.

• Journal of Korea Foundry Society
• /
• v.42 no.1
• /
• pp.3-11
• /
• 2022

In this study, the parameters on the shrinkage defect of HR3C alloy was secured through computer simulation research, and the ingot mold with greater than 85% of sound area was designed and manufactured. Moreover, the optimized coagulation was proposed at design stage through computer simulation and test was performed upon ingot manufactured. After the test, the defect pattern was analyzed through cutting and non-destructive inspection to verify the parameter and ingot mold design. Based on the verification results, shrinkage defect parameters such as Niyama, Feed Efficiency, and Hot Tear Intensity of HR3C Alloys were obtained. In addition, through the secured parameters, a plan for designing ingot mold with a Non-defect area of 85% or more was secured.

• Journal of Korea Foresty Energy
• /
• v.18 no.2
• /
• pp.70-77
• /
• 1999

The behaviors of alkali swelling in four major Korean woods were examined as a function of concentration cf alkali solution. Density of alkali-treated woods increased highly with increasing alkali concentration in both softwoods and hardwoods. Wood samples swelled in dimension during alkali swelling, and thereafter they shrank highly by water washing and air drying. The air-dried wood samples after alkali treatment showed almost isotropic shrinkage in tangential and radial direction.

• Steel and Composite Structures
• /
• v.6 no.2
• /
• pp.123-138
• /
• 2006

This paper proposes a model for the analysis of the construction sequences of steel-concrete composite decks in which the slab is cast-in-situ for segments. The model accounts for early age shrinkage, such as thermal and endogenous shrinkage, drying shrinkage, tensile creep effects and the complex sequences of loading due to pouring of the different slab segments. The evolution of the structure is caught by suitably defining the constitutive relationships of the concrete and the steel reinforcements. The numerical solution is obtained by means of a step-by-step procedure and the finite element method. The proposed model is then applied to a composite deck in order to show its potential.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.28 no.11
• /
• pp.1507-1515
• /
• 2004

Washable wool was developed using environmental-friendly spray UV-cure technique. Photocrosslinkable polymer, dextran-methacrylate, was synthesized starting from natural biopolymer, dextran. The aqueous solution of dextran-methacrylate was applied to wool fabric with various concentrations to find out the optimum condition in minimizing felting shrinkage. The wool fabric subsequently cured by 365 nm UV, The effects of UV-cure time and photoinitiator concentration on felting behavior of wool were examined. As the concentration of dextran-methacrylate increased, the felting shrinkage decreased gradually. At concentration 0.5g/ml, the felting shrinkage of wool was negligible. Other properties such as air permeability, moisture content, wrinkle recovery, thickness and wettability were also evaluated. The surface coating of dextran polymer onto wool fiber was identified by SEM.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.3
• /
• pp.426-434
• /
• 2000

This paper deals with a generalized similarity solution for the one-dimensional solidification of ternary or higher-order multicomponent alloys. The present approach not only retains the existing features of binary systems such as temperature- solute coupling, shrinkage-induced flow, solid-liquid property differences, and finite back diffusion, but also is capable of handling a multicomponent alloy without restrictions on the partition coefficient and microsegregation parameter. For an alloy of N-solute species, governing equations in the mushy region reduce to (N+2) nonlinear ordinary differential equations via similarity transformation, which are to be solved along with the closed-form solutions for the solid and liquid regions. A linearized correction scheme adopted in the solution procedure facilitates to determine the solidus and liquidus positions stably. The result for a sample ternary alloy agrees excellently with the numerical prediction as well as the reported similarity solution. Additional calculations are also presented to show the utility of this study. Finally, it is concluded that the present analysis includes the previous analytical approaches as subsets.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.649-652
• /
• 2008

In this paper, the applicability of hwangtoh, as an alternative of cement paste, is investigated for the solution of internal heat and shrinkage caused by the hydration of cement paste. Several small-sized specimens of hwangtoh and ordinary portland concrete(OPC) were compared as to compressive strength, heat of hydration, and shrinkage strain. Moreover, the applicability of mass structure was reviewed through the test of large-size specimens. The 28-day compressive strength of hwangtoh concrete(HBC), ranged 18 to 33 Mpa, can reach that of ordinary portland concrete. Not only the maximin internal temperature of HBC was read about 1/4 of OPC as it is cured, but also its drying shrinkage decreased as lower as 50% of OPC starting from 60 days. Therefore, hwangtoh binder is more favorable than cement one in the view of hydration heat and shrinkage under the construction of mass structures.