• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.2
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• pp.348-353
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• 2007

This paper presents design specifications and characteristics of bridge expansion joints to develop new type-joints in fiber reinforced polymer decks. Based on properties of the fiber reinforced polymer decks and fundamental process to calculate their expansion length, new expansion joints fur fiber reinforced polymer decks on typical steel or concrete girder are developed and proposed.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.233-234
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• 2010

Using an expansion admixture can reduce an initial shrinkage crack and improve a prestress. Therefore, this paper presents the results of a study performed to evaluate this deformation and obtain a better understanding of the behavior of SHCC using an expansion admixture. To evaluate a performance of SHCC using an expansion admixture was tested a drying shrinkage, compressive strength, flexural strength, and tensile strength.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.4
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• pp.180-188
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• 2013

The glass of E-glass fiber composition was fabricated by using refused coal ore which is obtained as by-product from Dogye coal mine in Samcheok. We used silica-alumina refused coal ore which has low carbon content relatively, and the amount of refused coal ore has been changed from 0 to 35 % in batch composition. E-glass was fabricated by the melting of mixed batch materials at $1550^{\circ}C$ for 2 hrs with different refused coal ore composition of 0~35 %. We obtained a transparent and clear glass with high visible light transmittance value of 81~84%, thermal expansion coefficient of $5.39{\sim}5.61{\times}10^{-6}/^{\circ}C$ and softening point of $851{\sim}860^{\circ}C$. The glass fiber samples were also obtained through fiberizing equipment at $1150^{\circ}C$, and tested chemical resistance and tensile strength to evaluate the mechanical property as a reinforced glass fiber of composite material. As the result, we identified the properties of E-glass fiber by using refused coal ore are plenty good enough compare to that of normal E-glass without refused coal ore, and confirmed the possibility of refused coal ore as for the raw material of E-glass fiber.

• The Korean Journal of Food And Nutrition
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• v.20 no.1
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• pp.47-52
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• 2007

The investigation of the textural characteristics of sponge cake with addition of polymannuronate(obtained from the polysaccharide, component of brown seaweed), were studied in order to assess the potential of polymannuronate as a dietary fiber and fat substitute. Hardness, gumminess, and chewiness of sponge cake were tended to progressively decrease in the response to the addition of polymannuronate. Low-butter treatment with constant level of polymannuronate increased hardness, gumminess, and chewiness while brittleness and springiness decreased. Sensory evaluation of sponge cake indicated that addition of polymannuronate(optimally at 3 and 5 w/w%), enhanced springiness, cohesiveness, and overall acceptability. The overall acceptability decreased P5C, P3C and P1C, P5B and control in the order. These results highlight the potential of polymannuronate as promising dietary fiber and fat substitute in sponge cake without compromising the textural characteristics.

• Journal of the Korea Concrete Institute
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• v.26 no.5
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• pp.651-660
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• 2014

Structural members using ultra high strength concrete which usually used with steel fiber is designed with guidelines based on several investigation of SF-RPC(steel fiber reinforced reactive powder concrete). However, there are not clear design method yet. Especially, SF-RPC member should be casted with steam(90 degree delicious) and members with SF-RPC usually used with precast members. Although the most important design parameter is development method between SF-RPC and steel reinforcement(rebar), there are no clear design method in the SF-RPC member design guidelines. There are many controversial problems on safety and economy. Therefore, in order to make design more optimum safe design, in this study, we investigated bond stress between steel rebar and SF-RPC according to test. Test results were compared with previously suggested analysis method. Test was carried out with direct pull out test using variables of compressive strength of concrete, concrete cover and inclusion ratio of steel fiber. According to test results, bond stress between steel rebar and SF-RPC increased with increase of compressive strength of concrete and concrete cover. Increasing rate of bond stress were decrease with increase of compressive strength of SF-RPC and concrete cover significantly. 1% volume fraction inclusion of steel fiber increase the bond stress between steel rebar and SF-RPC with two times but 2% volume fraction cannot affect the bond stress significantly. There are no exact or empirical equations for evaluation of SF-RPC bond stress. In order to make safe bond design of SF-RPC precast members, previously suggested analysis method for bond stress by Tepfers were evaluated. This method have shown good agreement with test results, especially for steel fiber reinforced RPC.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.2
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• pp.213-220
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• 2016

The needs for the utilization of space in the urban ara due to the increasing population and traffic volume. A Double-deck tunnel can be an appropriate solution. Geosynthetics are inevitably installed between ground and tunnel lining, therefore, geosynthetic-soil interface is also comprises. Dynamic shear behavior of geosynthetic-soil interface affects the dynamic behavior of tunnel, and experimental study is required since the behavior is very complicated. In this study, chemical factors such as acid and basic element in the groundwater and temperature are considered in the laboratory test. Multi-purpose Interface Apparatus(M-PIA) is utilized and submerging periods are 60 and 960 days. Consequently, dynamic shear degradation of geosynthetic-soil interface considering chemical and thermal factors are verified.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.4
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• pp.50-58
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• 2014

Due to the cost burden of new construction, the necessity of repair and retrofitting of aged structures is sharply increasing as the domain of repair and retrofitting construction is expanding. Because of the necessity, new technologies for repair and retrofitting are continuously studied in Korea and foreign countries. Steel adhesive method, fiber reinforced plastic (FRP) surface adhesive method, and external prestressing method are used to perform the repair and retrofitting works in Korea. In order to consider a repair method using steel mesh reinforced cement mortar (SMCM), 3-point flexural member test was conducted considering repair area and layer number of SMCM. Five types of specimens including ordinary reinforced concrete (RC) specimen with dimensions of $1400{\times}500{\times}200$ (mm) were cast for testing the deflection measurement, a LVDT was installed at the top center of the specimens. Also, a steel strain gauge and a concrete strain gauge were placed at the center of the specimens. A steel strain gauge was also installed on the shear reinforcement. The 3 point flexural member test results showed that the maximum load of SMCM reinforced specimen was higher than that of basic RC specimen in all of the load-displacement curves. Also, the results showed that, when the whole lower part of the basic RC specimen was reinforced, the maximum load and strain were 1.18 and 1.37 times higher than that of the basic RC specimen, respectively. Each specimen showed a slightly different failure behavior where the difference of the results was caused by the difference in the adhesive level between SMCM and RC. Particularly, in SM-B1 specimen, SMCM spalled off during the experiment. This failure behavior showed that the adhesive performance for RC must be improved in order to utilize SMCM as repair and retrofitting material.

• Journal of Korean Society of Forest Science
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• v.107 no.3
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• pp.287-293
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• 2018

This study was carried out to provide surface bearing capacity reinforcement of forest road by sub-base facilities based on a soft ground use of geosynthetics to prevent the damage of the road surface passing heavy logging trucks and to pass smoothly heavy truck against growing timber harvesting. The analysis of the road surface bearing capacity as progressing time and the increase of the number of passage of heavy logging trucks were conducted experimental section of forest road on the soft ground in the Forest Technology and Management Research Center. As a result, it was found that the road surface bearing capacity were stabilized at CBR of 15% or more, the effect of reinforcement by type of geosynthetics showed no significant difference after the lapse of about 1 year. After reaching the passage of 300 times for the heavy logging trucks on the sub-base construction section, the settlements was stabilized below the allowable standard of 50 mm, road surface bearing capacity also improved to more than CBR 20% and there was no significant difference in the thickness of the sub-base. However, in the section where the sub-base is not constructed, it is found that the lack of surface bearing capacity with the settlements more than the allowable standard is not possible to pass the heavy logging trucks. Therefore, in order to reinforce the road surface bearing capacity of the soft ground for the passage of the heavy logging trucks, it is necessary to construct a sub-base of at least 0.2 m when using geosynthetics.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.119-127
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• 2014

The application of sulfur polymer emulsion (SPE) as an acrylate substitute for semi-rigid pavement grout was evaluated, and the performance improvement by employing PVA fibers were also evaluated. The result indicated that the filling ratio of semi-rigid pavement material decreased as the fiber content increased, but it was measured to be 92~94% in every mixing condition, which satisfies the target performance, 90%. The maximum Marshall stability value of semi-rigid pavement material was measured to be 25.4 kN, which is about 4.7 times higher than the Korean Standard required for semi-rigid pavement material, 5.0 kN. The dynamic stability evaluation of semi-rigid pavement material indicated that the resistance to deformation from the wheel tracking test was improved by an SPE substitution, and in every mixing condition, the deformation converged to a constant value after 45 minutes with the same dynamic stability of 31,500 times/mm. The strain at the flexural failure was about 0.53%, which shows superior rigidity to asphalt pavements. The examination of abrasion resistance and impact resistance showed that the loss ratio was 9.8~6.0% in every mixing condition, which indicates a good abrasion resistance. Also, when fiber content ratio was 0.3%, the impact resistance was 2.82 times higher compared to plain (i.e., when fibers were not added). In the limited range of this study, an SPE substitution ratio of 30% was found to be an optimal level considering the mechanical and durability performance. In addition, it is thought that semi-rigid pavement material with superior performance could be manufactured if fiber content ratio up to 0.3% is applied depending on the purpose of use.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.10
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• pp.1726-1734
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• 2004

Response surface methodology on sensory evaluation was used to optimize cooking condition of cooked short grain rice (CSR) and cooked short grain rice containing grainy sea-tangle patch (CSTR). Texture profile analysis and nutritional evaluation were also performed. For maximizing overall acceptability, it can be predicted sea-tangle patch 14%, added water 1.67 times of rice and sea-tangle amount and steeping time 47 min as optimum cooking conditions from sensory evaluation conducted by the forties panelist. Hardness of pressure cooked short grain rice containing grainy sea-tangle patch (CSTR) were lower than cooked short grain rice (CSR), but it showed similar as CSR in adhesiveness, chewiness and higher in springiness and cohesiveness. In addition CSTR was delayed retrogradation compared with CSR. The nutritional Quality of CSTR showed higher level in total dietary fiber, protein, ash than CSR, but lower in protein digestibility, C-PER, gelatinization degree compared with CSR.