• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.356-362
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• 2016

Light-weight concrete uses forming agents for reducing weight and high heat insulation property. However, the forming agents make problems of decreased volume and compressive strength of the concrete. This research aims to having weight-reduction and securing heat insulation property using recycled wasted form polyurethane without any forming agents. A small quantity of admixture used for constructability and avoiding material segregation. We picked admixtures from two different companies which shows evenly dispersed of wasted form polyurethane. This research conducts a study on the effect of mixing ratio of admixture on the light-weight concrete used wasted form polyurethane. As a result of the test, increased mixing ratio of the admixtures results reduced fluidity of concrete. On the other hand, percentage of moisture content and compressive strength are increased slightly. Combustibility performance and sound insulation performance are also secured, as well.

• Journal of the Society of Disaster Information
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• v.11 no.3
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• pp.329-336
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• 2015

When diatomite powder was used as an admixture in mortar, its effects on the mortar strength was examined by experimental tests. For the tests, 4 kinds of commercially available diatomite powder were purchased ; one non-calcined product, one calcined product, and flux-calcined product two. The compressive and flexural strength of the mortar according to the increase of added amount of calcined diatomite powder increased at all test ages(7, 28, and 56 days). However, the use of non-calcined diatomite powder worsened the fluidity of mortar severely and that caused much more required water content. And flux-calcined product did not show useful effect on the mortar strength.

• Cement Symposium
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• no.25
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• pp.124-128
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• 1997

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.597-604
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• 2012

The present study assessed the $CO_2$ emissions of concrete according to the type and replacement ratio of supplementary cementitious materials (SCM) and concrete compressive strength using a comprehensive database including 2464 cement concrete specimens and 776 cement concrete mixes with different SCMs. The system studied in $CO_2$ assessment of concrete based on Korean lifecycle inventory was from cradle to pre-construction, which includes consistent materials, transportation and production phases. As the performance efficiency indicators, binder and $CO_2$ intensities were analyzed, and simple equations to evaluate the amount of $CO_2$ emission of concrete were then formulated as a function of concrete compressive strength and the replacement ratio of each SCM. Hence, the proposed equations are expected to be practical and useful as a guideline to determine the type and replacement ratio of SCM and unit content of binder in concrete mix design that can satisfy the target compressive strength and $CO_2$ reduction percentage relative to cement concrete.

• Journal of the Korea Concrete Institute
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• v.16 no.4 s.82
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• pp.485-492
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• 2004

In this study, ASTM C 1202 which is most commonly used for evaluating the penetration resistance into the concrete is reviewed. The test results by ASTM C 1202 showed that the passed charge could be underestimated as the $OH^-$ ion concentration in the concrete is lowered when the concrete is mixed with the admixtures. Therefore, the modified method using the distilled water was proposed in the paper. According to the test results, the modified method is not susceptible to $OH^-$ ion and temperature rise. In addition, the long term emersion test for the concrete mixed with the admixtures in the NaCl solution showed that the chloride diffusion coefficient tested by the modified method have higher correlation compared to the conventional ASTM method.

• Korean journal of applied entomology
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• v.12 no.2
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• pp.63-70
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• 1973

Weed control tests with 6 herbicides which seem to have selectivity of absorption by roots of rice were carried out by the rate of application, the depth of incorporation and the time of application in comparison with the after transplanting treatment of MO in SiCL soil. Soil-incorporated treatment of Ronstar, Saturn, TOK and Saturn·5 were applied before transplanting and soil surface treatment of Machete, PCP and MON·0385 were applied. The results are summarized as follows: 1. Initial crop injury and growth Soil surface treatment before transplanting of PCP of 1,000g ai/10a caused heavy initial injury, which was recovered from by about 50 days after application. Saturn-S at 4kg prod.110a caused slight crop injury sectionally, which was soon recovered from. And little crop injury was caused by other treatments. 2. Effect in weed control Excellent weed control of 90 to 97.7 percent was obtained, when measured 27 days after transplanting, by all the treatments. More than 90 percent weed control was maintained for about 73 days after transplanting by all the treatments of Ronstar and Saturn-S of 3 to 4kg prod./10a. The treatments of MON-0385 of 175g ai/10a and TOK of 280g ai/10a showed somewhat poor weed control. 3. Yield No reduction of yield was observed at all the plots except the non·weeded plot at which 11.4 percent yield reduction was observed compared with the hand weeding plot. The yield was increased by the 1 DBT and 2 DBT treatments of Machete of 210g ai/10a, the treatments of Ronstar of 60g ai/10a, when incorporated to the depth of 2.5 and 12cm, the incorporation treatment of Saturn-S of 3kg prod./10a and 1 DBT treatment of MON-0385 of 175g ai/10a.

• Polymer(Korea)
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• v.27 no.5
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• pp.405-412
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• 2003

Poly(vinyl alcohol) (PVA) and N-(2-hydroxy)propyl-3-trimethylammonium chitosan chloride (HTCC), a water soluble chitosan derivative synthesized by the reaction of quaternary ammonium compound with chitosan, were blended using water as a solvent and the PVA/HTCC blend films with various compositions were prepared by solution casting method. The miscibility between the two polymers and the thermal properties of the blend films were investigated using FT-IR, DSC, DMA, and TGA. Single glass transition temperatures and single melting temperatures of the blend films along with the strong and clear film state for the whole composition of blending ratios suggest the miscibility between PVA and HTCC. The PVA/HTCC blend films with HTCC content of 1% and greater showed excellent antimicrobial activity.

• Polymer(Korea)
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• v.24 no.6
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• pp.886-892
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• 2000

Poly(4-vinyl phenol) (PVPh) was neutralized by LiOH and PVPh ionomers (PVPh-Li) with different Li neutralization extents were synthesized. The variation in $T_{g}$ with Li neutralization was determined by DSC and the results show that the $T_{g}$ increases by 3.$8^{\circ}C$ per Li mol%. When comparing this result with the 3.$2^{\circ}C$ per Na mol% reported for poly (styrene-co-hydroxy styrene), the greater value for PVPh-Li may be due to a strong interaction between unneutralized free -OH and -OLi produced. No distinct small angle X-ray scattering (SAXS) peak was observed for these PVPh ionomers in bulk. In the 50/50 blend of PVPh-Li with PVPh, the miscibile blend was obtained when the Li neutralization in PVPh-Li was 10 mol%. On the contrary, the 50/50 PVPh-Li/PMMA was immiscible when the Li neutralization was 5 mol%. It can be concluded that, even if the starting blend is miscible owing to hydrogen bonding, the miscibility of blend becomes diminished by introducing small amount of ion groups into one of the constituent polymers and the blend can be immiscible as long as any new strong intermolecular ion-dipole interaction is not generated.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.1
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• pp.85-94
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• 2007

The EVA polymer is used as a modifier in the repair mortar, which contains various admixtures and mineral admixtures. It has been reported that the effect of polymer in cement mortar by the cement-polymer ratio only, but effect of admixtures over the polymer mortar was unknown. In this study, the fresh and mechanical properties of polymer cement mortar influenced by the range of admixtures(CSA expansive addictive, CSA accelerator, gypsum, silica fume) ratio were investigated.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.797-800
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• 2008

To decrease the usage of cement, the pozzolan reaction materials are used as a mineral admixture. Hwang Toh which is broadly deposited in Korea is well known as a environment friendly material and the activated Hwang Toh which has the property of pozzolan reaction is practically used as a mineral admixture of concrete. PET fiber which is made by recycled PET bottle controls micro crack in concrete. But the study about concrete mixed with reinforcing fiber is not enough and the property of Hwang Toh concrete mixed with PET fiber is more complicated case. So this study performed drying shrinkage experiment to analyse mechanical property of Hwang Toh concrete mixed with PET fiber.