• Magazine of the Korean Society of Agricultural Engineers
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• v.20 no.1
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• pp.4599-4613
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• 1978

This study was intended to investigate the effects of bituminous material content of soil-cement mixtures on their durability. For the purpose, unconfined compressive strength test, Freeze-thaw test, and wet-dry test were performed with three types of soil. Each type of soil was mixed with three levels of cement content and each soil-cement mixture was mixed with four levels of bituminous material content. For the unconfined compressive strength test, Freeze-thaw test and wet-dry test, 324, 108, and 108-specimens were prepared respectively. Unconfined compressive strength was measured at age of 7-days, 14-days and 28-days using 108-specimens in each age. The soil-cement loss rate due to freeze-thaw and wet-dry were calculated after 12 cycles of test using 108-specimens in each test. The results are summarized as follows : 1. Optimum moisture content was increased with increase of cement content, but maximum dry density was changed irregulary with increase of the cement content. 2. The unconfined compressive strength was increased with increase of cement content, bituminous material content and curing age. Cement is more effective factor than bituminous material on unconfined compressive strength of soil-cement Mixture. 3. It is estimated as the most economical cement content that the recommended cement content of A.S.T.M. because increasing rate of unconfined compressive strength at age of 28-days was low when cement content is above the recommanded cement content of A.S.T.M. among all types of soil. 4. Although a portion of cement content is substituted for bituminous material, the necessary unconfined compressive strength can be obtained. 5. The soil-cement loss was more influenced by wet-dry than Freeze-thaw 6. The bituminous material is more effective on the decrease of soil-cement loss than increase of unconfined compressive strength 7. The void ratio of soil-cement mixture was changet irregularly with increase of cement content, but that was decreased in proportion to the increase of bituminous material content. 8. The regression equation between the unconfined compressive strength and soil-cement loss rate were obtained as table 7.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.35 no.3
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• pp.29-36
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• 2003

Reducing the energy consumption while maintaining pulp quality is an important objective of today's paper industry. Enzymatic treatment of fibers and the application of dry strength agent were investigated as methods to reduce energy consumption during refining and to upgrade fiber characteristics. Modification of recycled fibers with an enzyme was effective in improving relining efficiency and reducing refining energy. Optimization of dry strength agent application conditions including stock pH, cationic demand, zeta potential, etc. were found to be very important for improving its effectiveness.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2010.05a
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• pp.63-65
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• 2010

The purpose of the study was to analyze dry shrinkage of HVFAC (high volume fly ash concrete) with admixture to improve early strength. The results were as follows. In dry shrinkage of HVFAC with admixture to improve early strength, F3 had the lowest amount of dry shrinkage. The next is in order of Plain, F3-f15 and F3-f15r5. The study used index function modelfor analysis on dry shrinkage. Coefficient of determination was more than 0.97 in all mix, which made it possible to have a good estimation.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.4 s.112
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• pp.26-31
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• 2005

The purpose of this study was to confirm paper strengthening properties with recently commercialized polyvinylamine. Because of its high cationic charge density, polyvinylamine has been investigated as a size retention and surface coating aids. In this study, we tried to confirm polyvinylamine as wet-end additives to improve dry and wet strength using LBKP and BCTMP pulps. As a result, we found improvement of dry and wet tensile properties of polyvinylamine with BCTMP were much better than LBKP condition. This phenomena could be explained that ionic bonding of cationic charge of polyvinylamine with abundant anionic substances of BCTMP was a very important factor to improve dry and wet strength of paper.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.239-244
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• 1999

In this study , the variation of dry density and unconfined compressive strength were investigated, calcium carbonate, quicklime, portland cement, 19mm monofilaments and fibrilllated fibers were used as reinforcement materials. And calcium chloride was added to cement and calcium carbonate reinforced soil mixture in order to accelerate setting and hardening speed. It appears that dry density is highest in calcium carbonate reinforced soil mixture with 9% of mixing rae. According to increasing the amount of fibers, in soil mixture , the dry density decreased. The more the amount of monofilament fibers is the higher the compressive strength. But the compressive strength is decreased in fibrrillated fiber added soil mixture with more than 1.0% of mixing rate.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.461-466
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• 1998

The purpose of this study was to evaluate the properties of unconfined compressive strength(UCS) of dry soil which was reinforced with short polypropylene fiber(SPPF). And the results were summarized as follows: 1. As water content was increased, unconfined compressive strength and strain of dry soil with no fiber added were decreased 2. As mixing ratio of fiber was increased, unconfined compressive strength and strain at failure of dry soil reinforced with SPPF were increased. 3. When mixing ratio was larger than 0.5％, unconfined compressive strength was gradually increased. 4. The longer fiber was, the larger post peak strength was obtained and the larger strain was reached.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.792-797
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• 2009

The stress-strain characteristics of compacted bentonite are investigated using experimental triaxial compression test by Hoek-cell. Special attention given to various dry density and water absorption ratio. Based on the test results, it is shown that the stress-strain relationship of compacted bentonite is highly influenced by dry density and water absorption ratio. Also, characteristics of Bentonite is similar to the clay rather than sand. Strength of compressed Bentonite increases with higher dry density. It shows maximum strength value, if in a same condition with dry density and constrain pressure. So we determine that value as the optimistic moisture contents for the maximun strength of compressed Bentonite.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.20 no.2
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• pp.79-91
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• 2017

This study was conducted to find out the physical properties and soil shearing strength reinforcement effect of herbaceous plants for the slope revegetation works. Two native plants(Pennisetum alopecuroides and Miscanthus sinensis) were used for this experiment, because they have excellent seed germination rates without preconditioning, and grow naturally around rivers. To identify the physical properties, the partial dry weight of plants were investigated. To identify the soil shearing strength reinforcement effect, the respective soil shearing strengths of the control soils, Pennisetum alopecuroides, Miscanthus sinensis samples were measured. Also, we did a correlation analysis to examine the relation of shearing strength to plant features. The results are summarized as follows: 1. The average dry weight of Pennisetum alopecuroides samples consists of 52.36% above ground and 47.64% at root. And in dry weight, 78.24% of it's root distributes within 10 cm in soil depth. Meanwhile the average dry weight of Miscanthus sinensis samples consists of 52.91% above ground and 47.09% at root. And in dry weight, 82.95% of it's root distributes within 10 cm in soil depth. 2. The results of correlation analysis showed that for both Pennisetum alopecuroides and Miscanthus sinensis, it could not be said that there was any correlation between shearing strength and plant characteristics, and statistically they were not meaningful. 3. In the shearing strength test with control soils, Pennisetum alopecuroides, Miscanthus sinensis as subjects, the differences in shearing strength measurement results were modest, and the order was shown as control soils < Pennisetum alopecuroides < Miscanthus sinensis, so the soil shearing strength reinforcement effect by the Pennisetum alopecuroides and the Miscanthus sinensis on loamy sand at river banks surface was confirmed.

• Computers and Concrete
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• v.26 no.2
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• pp.161-173
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• 2020

Shear keys in precast concrete segmental bridges (PCSBs) are usually match-casting which is very labour intensive. In this research, an innovative match-casting-free construction was proposed by leaving small gap between the convex and the concave castellated shear keys in the joints of PCSBs. Specimen experiment, shear strength analysis and numerical simulation were conducted, investigating the loading performance of this new type of dry joints, the gap dry joints. Compared with match-casting joint specimens, it has been found from experiment that shear capacity of gap joint specimens significantly decreased ranging from 17.75% to 42.43% due to only partially constrained and contacted in case of gap dry joints. Through numerical simulation, the effects of bottom contacting location, the heights of the gap and the shear key base were analyzed to investigate strength reduction and methods to enhance shear capacity of gap joint specimens. Numerical results proved that shear capacity of gap dry joints under full contact condition was higher than that under partial contact. In addition, left contact destroyed the integrity of shear keys, resulting in significant strength reduction. Larger shear key base remarkably increased shear capacity of the gap joint. Experimental tests indicated that AASHTO provision underestimated shear capacity of the match-casting dry joint specimens, while the numerical results for the gap dry joint showed that AASHTO provision underestimated shear capacity of full contact specimens, but overestimated that of left contact specimens.

• Proceedings of the KACD Conference
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• 2001.11a
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• pp.587.2-587
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• 2001

The purpose of this study is to evaluate influence of moisture control on bond strength of self-etching primer by measuring enamel and dentin shear bond strengths. 96 extracted human molars were divided into 8 groups. Group 1 (Enamel 30min Dry), Group 2 (E. 5s air dry), Group 3 (E. 1s air dry), Group 4 (E. blot dry), Group 5 (Dentin 30min Dry), Group 6 (D. 5s air dry), Group 7 (D. 1s air dry), Group 8 (D. blot dry) were divided.(omitted)