• Journal of environmental and Sanitary engineering
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• v.23 no.1
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• pp.57-65
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• 2008

Resins were synthesized with 1-aza-15-crown-5 macrocyclic ligand attached to styrene(dangerous matter) divinylbenzene(DVB) copolymer with crosslink of 1, 2, 6 and 15% by substitution reaction. The synthesis of these resins was confirmed by content of chlorine, element analysis, and IR-spectrum. The effects of pH, time and crosslink on adsorption of metal ion　from water fire extinguishing agent by the synthetic resin adsorbent were investigated. The metal ion was showed fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in water was in increasing order of $Mg^{2+}>Al^{3+}>Pb^{2+}$. The adsorption was in the order of 1, 2, 6, and 15% crosslink resin.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.10 no.1
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• pp.49-74
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• 1984

Rheology of gels prepared with stearyl dimethyl benzyl ammonium hectorite (SDBAH) and various polar additives in n-butyl acetate was investigated by measuring the viscosity and rheogram. Including generally recognized polar additives, additional studies on the rheogram and viscosity were made with ether-type methyl cellosolve and carbitol, with dimethyl sulfoxide (DMSO) having sulfonyl group, and furthermore with above-mentioned polar additives containing small quantity of water, It was observed that molecular size, dipole moments and dielectric constants of polar additives had a great influence on viscosity increase and rheology of SDBAH gel, and the increase of SDBAH interlayer spacing was important factor in gel formation and viscosity change. It was also shown that thixotropy effect was increased with the increase of polar additive concentration, finally changed to rheopexy from thixotropy as the concentration of polar additives was increased more than about 40% of SDBAH weight. In addition thixotropy changed to rheopexy as the increase of shear rate. It was further found that the aqueous solutions of polar additives (water content, 5-25%) had more effects on rheology than additives without water, and particularly 95clo DMSO solution was the most effective. And the optimum concentration of polar additives showing maximum viscosity in the same SDBAH concentration system was examined.

• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.93-99
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• 2000

The physical properties of freshly mixed steel fiber reinforced recycled concrete(SFRRC) were_investigated. Physical state and quality of fresh concrete were monitored batch by batch. the properties of freshly mixed SFRRC were determined in terms of slump, air content, superplasticizer, and bleeding ratio. Concrete mixtures were produced for three kinds of aggregate proportions. So, the experimental variables are various aggregate proportions, steel fiber contents(0, 0.5, 1.0, 1.5%) and steel length(30, 50, 60mm). From experimental results, optimum s/a by various experimental variables, variations of the slump by the air contents, and optimum superplasticizer to decrease unit water were presented.

• Food Science and Preservation
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• v.9 no.4
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• pp.396-399
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• 2002

An attempt was made in this study to investigate the optimum extracting time from meat with bone of goat and the nutritional component of its extract. for the trials, the mixtures of meat with bone and water were adjusted to the ratios of five to four by weight and extracted for 6, 9 and 12 hours at 120$\^{C}$ under autoclave. Judging from the content of mineral and amino acid, nonenzymatic browning and yield, the optimum extracting time was 9 hours. The major components of mineral were composed of 47.7mg％ potassium, 12.7mg% calcium, 150.0mg% sodium, 105.3mg% phosphorus and 0.5mg% iron, and of amino acids composed of 1,308.0mg% glutamic acid, 1,464.2mg% glycine, 750.2mg% alanine and 828.lmg% proline in extract. The yield of extract was 32.1 percentage by dry basis.

• Journal of the Korean Geotechnical Society
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• v.40 no.3
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• pp.93-100
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• 2024

Pore water freezes in low-temperature compaction, which leads to different compaction characteristics compared to room temperature conditions. In regions like Alberta, Canada, where organic soils are prevalent, compaction performance is influenced by the high water retention and compressibility of organic soils, as well as their sensitivity to freezing and thawing. Alberta's strict environmental regulations demand the reuse of excavated soil for backfill, and the long winter season creates challenging conditions for civil engineering projects. In this study, a laboratory compaction test was conducted to evaluate the low-temperature compaction characteristics of organic soils with varying organic content. The results indicate that the optimum moisture content increases as the organic content increases, and the maximum dry unit weight decreases by up to 21.9%. In addition, under temperature conditions below -4℃, no optimum moisture content was observed, and the dry unit weight decreased as the moisture content increased.

• Journal of Welding and Joining
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• v.7 no.2
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• pp.49-59
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• 1989

The effect of non-metallic inclusions on the HAZ hydrogen induced cracking was investigated. Quench and temper high tensile strength steels containing various sulphur contents were employed. The sulphur contents range between 0.007% and 0.040%. Non-metallic inclusions were mainly MnS type sylphide and Mn-Al-Si type. The sensitivity of HAZ delayed cracking was evaluated by implant testing. Diffusible hydrogen content was varied by controlling the moisture absorbing condition of manual arc welding electrodes. The one was asreceived condition, the other was dipping the electrodes in the water for ten minutes. The main results obtained were as follows; 1) The results of implant test showed that critical stress increased with increasing S content up to 0.013%. But steel containing 0.040%S showed lower critical stress than that of 0.013% S. These result suggest that there will be optimum S content to prevent HAZ delayed cracking of high strength steels. 2) Under the lower D.H.C. level, critical stress was increased with rolling reduction, but higher D.H.C. level, effect of rolling reduction was not recognized.

• Journal of Mechanical Science and Technology
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• v.17 no.4
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• pp.581-589
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• 2003

Film absorption involves simultaneous heat and mass transfer in the gas-liquid system. While the non-absorbable gas does not participate directly In the absorption process. its pretence does affect the overall heat and mass transfer. An experimental study was performed to investigate the heat and mass transfer characteristics of LiBr-H$_2$O solution flow ing over 6-row horizontal tubes with the water vapor absorption in the pretence of non-absorbable gases. The volumetric concentration of non-absorbable gas, air, was varied from 0.17 to 10.0%. The combined effects of the solution flow rate and its concentration on the heat and mass transfer coefficients were also examined. The presence of 2％ volumetric concentration of air resulted in a 25% reduction in the Nusselt number and 41% reduction in the Sherwood number Optimum film Reynolds number was found to exist at which the heat and mass transfer reach their maximum value independent of air contents. Reduced Nusselt and Sherwood numbers. defined as the ratio of Nusselt and Sherwood numbers at given non-absorbable gas content to that with pure water vapor, were correlated to account for the reduction in the heat and mass transfer due to non-absorbable gases in a falling film absorption process.

• Plant Resources
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• v.2 no.1
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• pp.42-48
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• 1999

This study was undertaken to examine the feasibility of black locust (Robinia pseudoacacia) as substrates for several edible mushrooms. For the cultivation of several edible and/or medicinal fungi on black locust, optimum bulk densities, synthetic or semisynthetic additives, natural additives and pretreatment methods were investigated. Fruit body yields of the fungi on various sawdust media composed of different wood species were also analyzed for testing the capability of black locust as a substrate for mushroom production. Mycelial growths decreased proportional when the bulk density increased. The most suitable carbon and nitrogen sources as additives to promote the mycelial growth were sucrose (2%, w/w) and ammonium phosphate (0.2%, w/w) respectively. When corn-powder and beer-waste as natural additives were added to sawdust of black locust showed the significant growth of mycelia. And the optimum mixing ratio was 10:2:1 (sawdust: corn-powder: beer-waste, w/w). Black locust after cold water treatment showed the outstanding mycelial growths. Any significant changes of pH, moisture content (%) and dry-weight losses (%) could not be found among culture substrates (sawdust of black locust, oak and poplar wood) examined before and after harvesting of fruit bodies. Yield of fruit bodies on black locust culture media were comparable with those culture media composed with oak and poplar wood. The present work indicated strongly the potentiality of black locust as raw materials for edible and medicinal mushrooms.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.36-42
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• 2018

GGBFS(Ground Granulated Blast Furnace Slag)-replacement is very effective for improving resistance to chloride attack and this can induce a long service life for RC(Reinforced Concrete) structures exposed to chlorides. In the work, the design parameters such as cover depth, surface chloride content, critical chloride content, and replacement ratio of GGBFS are considered, and optimum replacement ratio of GGBFS are derived with intended service life. The changes of surface chloride content and cover depth show 3.16~3.38 and 3.02~3.34 times of service life variation, which are most influencing parameters. Critical chloride content shows 1.53~1.57 times of service life variation regardless of w/b(Water to Binder) ratios. In the case of surface chloride content $18.0kg/m^3$, the most severe condition, cover depth over 70 mm and GGBFS replacement ratio over 42% are required with concrete containing w/b ratio under 0.42 for 100 years of intended service life. The condition of $13.0kg/m^3$, GGBFS replacement over 35% is required. For reasonable durability design, quantitative exterior condition and critical chloride content should be determined, and the criteria in Domestic Specification is evaluated to be conservative.

• Advances in concrete construction
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• v.6 no.2
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• pp.103-121
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• 2018

This paper reports the effects of coarse and fine recycled concrete aggregates (RCA) on fresh and hardened properties of self-compacting concrete (SCC) containing ground granulated blast-furnace slag (GGBFS) as cement replacement. For this purpose, three SCC mixes groups, were produced at a constant water to binder ratio of 0.38. Both fine and coarse recycled aggregates were used as natural aggregates (NA) replacement at different substitution levels of 0%, 25%, 50%, 75% and 100% by volume for each mix group. Each group, included 0, 15% or 30% GGBFS as Portland cement replacement by weight. The SCC properties investigated were self-compactability parameters (i.e., slump flow, T500 time, V-funnel flow time, L-box passing ability and sieve stability), compressive strength, capillary water absorption and water penetration depth. The results show that the combined use of RCA with GGBFS had a significant effect on fresh and hardened SCC mixes. The addition of both fine and coarse recycled aggregates as a substitution up to 50% of natural aggregates enhance the workability of SCC mixes, whereas the addition from 50 to 100% decreases the workability, whatever the slag content used as cement replacement. An enhancement of workability of SCC mixes with recycled aggregates was noticed as increasing GGBFS from 0 to 30%. RCA content of 25% to 50% as NA replacement and cement replacement of 15% GGBFS seems to be the optimum level to produce satisfactory SCC without any bleeding or segregation. Furthermore, the addition of slag to recycled concrete aggregates of SCC mixes reduces strength losses at the long term (56 and 90 days). However, a decrease in the capillary water absorption and water permeability depth was noticed, when using RCA mixes with slag.