• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.4
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• pp.422-427
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• 1989

Weeds may compete detrimentally with the ginseng for moisture and nutrients but hand weeding is the only practical means of eliminating weeds after crop establishment. To define the effects of 2, 4-D herbicide application on the plant growth and root yield of Korean ginseng (Panax ginseng C. A. Meyer). the herbicide 2, 4-D was applied as a foliar spray with the rates of 0.5. 1.0. 1.5 and 2.0 times of the recommended herbicide dosage 70ml/l0a. The Korean ginseng treated with 2, 4-D in the rate of two times concentration was indistinguishable from nontreated plants in visual rating for foliar symptoms. There were no significant differences of the leaf length and width as well as the stem length and diameter in check plants and those recieving 2, 4-D treatments. The. berry maturing in 3 and 4-years old ginseng was not inhibited with 2, 4-D treatment. The root weight of the 4-years old ginseng plant was not reduced by 2, 4-D application of 2 times dosage. However. when the ginseng seedling was treated with 2, 4-D. detrimental phenomena as stem bending and dicoloration of marginal part of seedling leaf were occured but stem bending was recovered in a few days.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.777-780
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• 2008

According to the recent tendency that the buildings in the downtown are gradually Manhattanized, the very thick massive concrete is selected as the foundation of architectures. By the way, because this mass concrete cannot be simultaneously pour in a great quantity due to the circumstance at the field, not only the questions on the unification between the concretes pour on the upper layer and the lower layer are presented but also the cracks by the internal force from the difference of hydration exothermic period are occurred, which are pointed out as the problems. Thus, this study performed Mock-up test to apply the hydration heat controlling method of massive concrete for horizontal partition pouring construction to the building sites for the purpose of securing the stability on the cracks by the internal force from the difference of hydration exothermic period on the upper layer and the lower layer of massive concrete and checked the efficiency. As the results of test, in case of setting time difference method by super retarder with 2 layers and 4 layers, the effect that temperature gaps between upper part and lower part were lowered and the possibility of crack occurrence was decreased as the peak time of the heat of hydration became delayed to the latter term could be confirmed.

• Journal of the Korea Institute of Building Construction
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• v.16 no.1
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• pp.1-7
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• 2016

In this research, it used cement powder and reduction slag, which generates high hydration heat in hydration reaction without heat cure below $-5^{\circ}C$ degree. Purpose of final research is preventing freezing and thawing by making the compressive strength 5MPa in 3days below zero temperature due to own heat of concrete. and it is the result of physical characteristic and thermal property evaluation of reduction slag. Because reduction slag generates high hydration heat, compressive strength development is excellent. By generating highly hydration heat by $C_{12}A_7$ and $C_3A$ in reduction slag, compressive strength is developed in low temperature. In case of displacing only reduction slag without $SO_3$, it is indicated that quick-setting occurs by shortage of $SO_3$. For preventing quick-setting, gypsum is used essentially. According to this research result, in case of using reduction slag and gypsum as a ternary system, compressive strength developed 5MPa in 3 days below zero temperature. It is identified to prevent early frost damage of concrete below zero temperature.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.403-413
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• 2017

In this paper, to increase the use of industrial byproducts for $CO_2$ reduction and to improve construction performance, it was manufactured that $CO_2$ reduction type quaternary component high fluidity concrete (QC-HFC) with Reduced cement usage by more than 80% and its quality and hydration characteristics were evaluated. QC-HFC was found to satisfy the target performance, and the flow and mechanical properties were similar to those of conventional concrete. The drying shrinkage of QC-HFC decreased about twice compared with the conventional blend, and the hydration heat decreased about 36%. As a result, it can be concluded that the amount of cracks can be reduced by reducing temperature stress due to hydration heat reduction effect and reducing deformation due to relatively small temperature difference between inside and outside. Also, As a result of the simulation of the mass structure, the temperature cracking index of QC-HFC is 1.1 or more, and the cracking probability is reduced by about 35%, so that the crack due to temperature can be reduced.

• Journal of the Korean Ceramic Society
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• v.35 no.5
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• pp.479-485
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• 1998

Raw mateials such as limestone quartzite bauxite and anhydrite were used in the production of mod-ified beloite cement. Two kinds of clinker were synthesized with relatively higher content of $C_2S$ than that of $C_4A_3{\={S}}$ Concerning $C_2S$ the main mineral component borax ($Na_2O\;2B_2O_3\;10H_2O$) was added to stimu-late hydraulic reactivity and this would be possible by stabilizing ${\alpha}'-C_2S$ at room temperature. We had in-tended to compare burning and hydraulic characteristics of clinkers with one another by varying the amount of borax addition and to study the appropriate amount of anhydrite addition needed in the strengthening of cement during hydration. It was concluded that the effective amount of borax addition ne-eded for stabilization of ${\alpha}'-C_2S$ was 5 wt% in 60wt% $C_2S$ inclusive clinker and adding anhydrite in the ra-tio of 1.3 of $SO_3/Al_3O_3$ was appropriate in the production of cement by this clinker. Only ettringite was seen to contribute to the strength without additives but C-S-H was found to form along with ettringite with the addition of borax in the initial stage of hydration.

• Food Science and Preservation
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• v.23 no.6
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• pp.819-824
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• 2016

The changes in physicochemical characteristics and sensory evaluation of bracken (Pteridium aquilinum) and Aster scaber dried by different methods sun-dried, hot-air-dried and freeze-dried were investigated. The freeze-dried Aster scaber showed the lowest moisture content than those of sun-dried and hot-air-dried. Freeze-dried bracken and Aster scaber showed higher rehydration rate than sun-dried and hot-air-dried. In the color values, the freeze-dried bracken and Aster scaber had the highest $L^*$ value of 29.48 and 32.73, respectively, while freeze-dried Aster scaber showed the lowest $a^*$ value of -6.78. Rehydrated bracken and Aster scaber after freeze-dried were the highest value in $L^*$ and $b^*$, while the lowest in $a^*$ value. In sensory evaluation, freeze-dried bracken and Aster scaber showed the highest in color, appearance, flavor, texture and overall acceptability. There were no significant differences in texture between hot-air-dried bracken and freeze-dried bracken after rehydrating. However, freeze-dried bracken and Aster scaber were the highest in color, appearance, flavor and overall acceptability. In conclusion, freeze-dried bracken and Aster scaber showed the best rehydrated rate, color and sensory properties.

• Journal of the Korean Geotechnical Society
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• v.20 no.9
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• pp.25-32
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• 2004

Some amount of cements can be added into the soil with high water content to improve the engineering properties. In such a case, it is difficult to predict and figure out the phase changes of the soil-cement mixture which is closely associated with workability of the soil-cement mixture. Changes in heat of hydration and hardness of the cement pastes are known to provide the useful information about the phase changes of the soil-cement mixtures. In this study, heat of hydration and cone penetration depth were measured from the specimens of cement paste and 3 soil-cement mixtures. From the experimental results, it was found that the phase changes of the soil-cement mixtures are the same as those of cement paste, and that shear strength of the mixtures abruptly increases when the heat of hydration is minimum. Initial setting time of the mixtures coincides with the state when fall cone penetration depth was 1.0 mm and it is defined as plastic limit of the mixtures. Initial setting time of the mixtures is retarded as soil/cement ratio is increased. Measurements of heat of hydration and fall cone apparatus could be the useful tools to predict the phase changes of tile soil-cement mixtures.

• Korean Journal of Food Science and Technology
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• v.32 no.1
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• pp.90-96
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• 2000

The optimum cooking conditions for large scale continuous gas cooker were studied with three varieties of rice. Optimum soaking time for the cooker was estimated to be 30 min at cooking temperature above $20{\circ}C$, while 60 min at cooking temperature below $10{\circ}C$. The ratio of water-to-milled rice giving the best eating quality was founded to be $1.41{\sim}1.48$, and corresponding moisture content of cooked rice ranged from 60 to 62% for different rice varieties. The optimum ratio of water to milled rice. (Chucheong) decreased from 1.50 to 1.37 with increase in the amount of milled rice from 4.0 to 6.5 kg in a cooking vessel. However, actual water uptake by rice (g water absorbed per g rice) on cooking was nearly constant value of 1.13, which means that evaporated water during cooking increases with decreasing the amount of rice in a cooking vessel.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.185-190
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• 2021

Cement has been used as a main material in the modern construction industry. However, it has been pointed out as a main cause of global warming due to carbon dioxide generated during manufactured. Recently, research that replacing cement substitute to industrial by-products such as Blast Furnace Slag which is by-producted in steelworks. When Blast Furnace Slag is used as a cement substitute, it shows a problem of lower initial strength, which is caused by glassy membrane on the particle surface. In this study, we used Electrolysis Alkaline Aqueous to improve the usability and problem of lower initial strength. As a result of the experiment, cement matrix using Blast Furnace Slag and Alkaline Aqueous showed initial strength and hydrate product were developed than that using general mixing water. Also, as a result of porosity analysis, It was confirmed that cement matrix using Alkaline Aqueous and Blast Furnace Slag has a tighter structure in internal porosity and porosity distribution than using general mixing water.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.152-160
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• 2021

Converter steel slag(BOF slag) is a vast amount of solid waste generated in the steelmaking process which has very low utilization rate in Korea. Due to the presence of free CaO which can derive bad volume stability in BOF slag, it usually land filled. For recycling BOF and identify its applicability as fine aggregate, this study investigates the fundamental characteristics of mortar with cement replaced ferronickel slag(FNS), which has the potential to be used as a binder. The results suggest that the mineral phases of BOF slag mainly include larnite(CaSiO₄), mayenite(Ca₁₂Al₁₄O₃₃) and wuestite(FeO) while olivine crystallines are shown in FNS. The results of flow and setting time reveals that the flowability and process of hardening increased when the amount of FNS and BOF slag incorporated was increased. The length change shows that the amount of change in the length of the mortar was almost constant regardless of mix proportion while compressive strength was reduced. Micro structure test results revealed that FNS or/and BOF slag mix took a long time to react in the cement matrix to form a complete hydration products. To achieve the efficient utilization of B OF slag as construction materials, proper replacement rate is necessary.