• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.345-348
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• 2004

In this study, an effect of fiber blending on material property of hybrid fiber reinforced concrete (HFRC) was evaluated. Also, optimized association and the mixing rate of fiber for HFRC was determined. Test result shows, in the case of mono fiber reinforced concrete, use of steel fiber in concrete caused increment in tensile and bending strength as the blended ratio increases, while use of carbon fiber and glass fiber caused increment in compressive strength. Use of hybrid fiber reinforcement in concrete caused a significant influence on its fracture behavior; consequently, caused increase by mixing rate of steel fiber and contributed by carbon fiber, glass fiber, celluloid fiber in reinforcement effect in order.

• Journal of the Korea Institute of Building Construction
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• v.20 no.1
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• pp.27-34
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• 2020

In the industry, due to the carbon dioxide gas produced during cement production is increasing, research on recycling by-products has been actively conducted. In the industrial by-products, the high calcium fly ash(HCFA) produced by the blast-furnace in the circulating fluidized bed combustion method has a high ratio of CaO and CaSO4. In view of this, the purpose of this is to use high calcium fly ash(HCFA) as a stimulant in blast furnace slag powder and use it as a cement substitute. As a result, it is judged that the substitution ratio of HCFA should be 15% or less. In addition, although durability and strength are relatively lower than of OPC, it is considered that it can be utilized as an environmentally building material.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.1
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• pp.37-44
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• 1992

Germinability, electrophoretic variation of protein of shattered seeds during overwintering and characteristic of main agronomic traits of off-type rice plant occurring in paddy field harvested by combine were investigated. Germinability of shattered seed decreased as time goes in paddy field in both Japonica and Tongil type varieties. Electrophoretic protein bands become more and more light as time goes. Occurrence of off-type rice plant was higher in Japonica varieties than in Tongil type varieties. Off-type rice plant was shorter in plant height, leaf length, tiller number per hill, internode length, panicle length and spike let number per panicle. Germinability of seeds of off-type rice plant as not significantly different compared to the control variety. Yield of off-type plants of Japonica varieties was on average 5.1kg / 10a and that of Tongil type varieties was on average 0.9kg /10a. Mixing ratio to the control variety was about 0.7% in Japonica varieties and that of Tongil type varieties was about 0.1%.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.6
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• pp.1743-1751
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• 2014

It is well known that latex modification can lead to enhancement compressive and flexural performance, tensile bond strength, chloride penetration resistance and freezing-thawing resistance for concrete. For these, many studies for LMC pavement have been widely conducted more than those for conventional pavement concrete. However, due to several problems such as noise and construction cost, new approaches for LMC have been executed to improve the performance of LMC. Recently, Remicon LMC was developed in order to solve the problems of LMC. In this study, the durability of Remcion LMC was compared with latex and mineral additive mixing ratio. From the results, when latex and mineral additive were mixed in Remicon LMC, compressive, flexural and bond strength were satisfied with Korea Highway Construction Guide Specification. And, it showed that the qualitative effect of latex and mineral additive mixing ratio on the durability of Remicon LMC was investigated experimentally. Also, the latex mixed in Remicon LMC must be at least 8%, in order to ensure the durability equivalent or higher than conventional LMC.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.602-608
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• 2021

Recently, research and development has been conducted to impart high performance and functionality to concrete materials by mixing various reinforcing materials into the matrix. Ductile fiber reinforced concrete using a large amount of fibers shows a distributed multiple cracking behavior, and various studies are being conducted on this material. However, research is focused on static behavioral analysis but studies on cyclic behaviors are not sufficient. In this study, beams were made of ductile fiber reinforced concrete with various fiber contents, and static and fatigue flexural tests were performed. As a result, the effect of fiber content on the flexural behavior was analyzed. Also, the applied load level and fatigue life relationship of ductile fiber reinforced concrete was proposed. Concrete with high ductile property could be achieved with a fiber content of 2%. When 0.5% fiber was more added, the maximum flexural strength was similar, but the flexural toughness is nearly doubled. On the other hand, there was no significant difference in the fatigue life of these two mixtures.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.343-350
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• 2022

In recent years, nanomaterials, such as nano-silica, carbon nanotubes, and graphene oxide (GO), have been suggested to improve the properties of the interfacial transition zone (ITZ) between aggregates and cement pastes, which has most adversely affected the strength of quasi-brittle concrete. Among the nanomaterials, GO with superior dispersibility has been reported to be effective in improving the properties of ITZ of normal-strength concrete by forming interfacial chemical bonds with Ca²⁺ ions abundant in ITZ. In this study, the effect of GO on the properties of ITZ in the high-strength mortar was elucidated by calculating the change in hydration heat release, ITZ thickness, and the porosity around ISO sand, which was obtained with isothermal calorimetry tests and scanning electron microscope image analysis, respectively.

• Journal of the Korean Applied Science and Technology
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• v.39 no.5
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• pp.720-726
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• 2022

The behavior changes of the lipid bilayer, induced by the hydroxybutyric-acid incorporation, were investigated with respect to each phase of the layer using fluorescence intensity change. Spherical phospholipid bilayers, called vesicles, were prepared using an emulsion technique. Only in the aqueous inside of the vesicles was encapsulated 8-Aminonaphthalene-1,3,6-trisulfonic-acid-disodium-salt(ANTS). p-Xylene-bis-N-pyridinium-bromide(DPX) was included as a quencher only outside of the vesicles. The fluorescence scale was calibrated with the ANTS-encapsulated vesicles in DPX-dispersed-buffer taken as 100% and the mixture of ANTS and DPX in the buffer as 0%. Hydroxybutyric-acid addition into the vesicle solution led the change in the bilayer. The change was found to be related to the phase of each layer according to the ratio of hydroxybutyric-acid to lipid. These results seem to depend on the stability of the vesicles, due to the osmotic and volumetric effects on the arrangement in both head-group and tail-group.

• The Korean Journal of Mycology
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• v.34 no.2
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• pp.73-78
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• 2006

Attempts were made to investigate the physiological and genetic changes when two different shiitake (Lentinula edodes) strains are mixed. Mycelial growth of KFRI 180 strain and KFRI 1 strain were investigated 82 mm and 80 mm, respectively. Concerning the weight loss percentage of medium, KFRI 1 strain decreased 2.4% and KFRI 180 strain 1.6%. Plug-shaped spawn had no-problem to incubate and there were no differences among the ratios of mixture. Also, conditions of plug-shaped spawns were similar, When the isolated mycelia from plugshaped spawns was incubated again, KFRI 1 50%-KFRI 180 50% showed decreased growth of mycelia compared with other treatments. The same results were obtained from test tubes filled with sawdust. When surface of spawn bottles were observed, KFRI 1 50%-KFRI 180 50% showed spots, but other treatments were not different from KFRI 1 and KFRI 180. Test was made to confirm the strains by confrontation culture. The mixture of two strains was proved to be KFRI 1 regardless the ratios of mixture. However, by the RAPD primer analysis, when KFRI 1 was mixed with KFRI 180, KFRI 180 was stronger. Thus, the confrontation line on PDA was different from the bands analysis by primers. Attempts were made whether the fruit-bodies were made at the generating condition of spawn bottles. The results were that KFRI 1 100%, KFRI 1 90%-KFRI 180 10%, KFRI 1 80%-KFRI 180 20%, KFRI 1 50%-KFRI 180 50% treatment showed fruit-body formation. The shape of fruit-body was deformed, but the gill was made normally.

• Korean Journal of Food Science and Technology
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• v.41 no.6
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• pp.722-726
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• 2009

The residue distribution ratio of pesticides among the flesh, stem and leaves of hot peppers were investigated to assure the safety of pepper powder and pepper leaves. Mixed solutions of chlorothalonil (wettable powder), kresoximmethyl (water dispersible granules) and procymidone (wettable powder) were applied once onto pepper plants in a plastic film house. After 7 days, the fruits and leaves were harvested and the fruits were divided into the flesh and stems. Pesticide residues in each pepper part were then analyzed by gas chromatography. The results showed that the concentration ratios of the chemicals in the flesh:stem and flesh:leaf ranged from 1:2-5 and 1:11-39, respectively, depending on the chemical evaluated. The observed flesh:stem ratio indicates that the pesticide content of the pepper powder product can increase by 20% if pepper stems are included in the powder product. The Korea Food and Drug Administration does not set a pesticide maximum residue level (MRL) for pepper leaves if a residue ratio in leaves over flesh is more than ten times. Results from this study support non-MRL status on the pepper leaves for the studied pesticides. Additionally, we recommend that the chlorothalonil product of a wettable powder type include the phrase "prohibition of distribution or sale for pepper leaves as food" because chlorothalonil highly resided in pepper leaves as more than twenty-four times that is a criterion level to determine an inclusion of the phrase in the label of pesticide product.

• Journal of Bio-Environment Control
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• v.16 no.2
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• pp.101-107
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• 2007

This experiment was carried out to develop the substrate mixtures for the production of high quality plug seedlings of cucumber. Peatmoss based substrates, rice hull, carbonized rice hull, decomposed sawdust, perlite and granular rockwool were mixed by five different mixing ratioes (M1, M2, M3, M4 and M5). The cultivars used were cucumber (Cucumis sativus L. cv. Janghyung heukjinju) plants. The higher the content of peatmoss added, the higher the plant growth in terms of plant height, leaf area and total dry weight, which leading to the production of high quality plug seedlings. Seedlings growth of cucumber were greater in M5 mixtures [peatmoss:rice hull:decomposed sawdust=40:40:20(v/v)], M4 mixtures [peatmoss:rice hull:decomposed sawdust:granular rockwool=30:25:20:25(v/v)] and M2 mixtures [peatmoss:rice hull:decomposed sawdust:granular rockwool=20:20:15:25:20(v/v)] The concentrations of nutrient solution (EC) had a great influence on plant height, leaf area, total fresh and dry weight of cucumber seedlings growth. As the concentration of nutrient solution increased from 0.1 to $1.5dS{\cdot}m^{-1}$, the growth and seedling quality of cucumber in plant height, leaf area and dry weight were significantly improved.