• Korean Journal of Food Science and Technology
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• v.18 no.1
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• pp.66-70
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• 1986

Storability of strawberry in air with the different levels of $CO_2$, for CA storage were measured. The strawberries stored in air included 20% and 30% $CO_2$, for 5 weeks decayed 14% and 10%, respectively, while the decay rate of the strawberries stored in normal air for 2 weeks was 53%. Firmness and 'a' value in Hunter Color Measuring Scale of the strawberries kept in the CA storage conditions were superior to those of the strawberries stored in normal air during storage. The concentrations of ethyl alcohol and acetaldehyde were increased with storage period and they were less in the strawberries in air with 30% $CO_2$, than those of the strawberries stored at the other conditions.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.561-564
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• 2008

Concrete scaling is the progressive surface deterioration of susceptible subjected to freeze-thaw cycling in the presence of moisture. Particularly, it has been recognized that chlorides present in deicing agents can significantly increase concrete surface scaling. Domestic area of most be happened chloride deicer damage. Because daily mean temperature is below 0$^{\circ}C$ from the area of domestic most. Use of deicing chemicals has been and will continue to be a major part of highway snow and ice control methods. Chloride-containing chemicals such as calcium chloride or rock salt are main deicers for the road. Extensive use of chloride deicers is, however, not only the source of substantial cost penalties due to their corrosive action and ability to deterioration roadway surface materials but also the source of environmental damages. In this study, Use of (40, 27, 21MPa) pavement concrete analyze freeze-thaw test and scaling on the chlorides present.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.565-568
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• 2008

Domestic area of most be happened chloride deicer damage. Because daily mean temperature is below 0$^{\circ}C$ from the area of domestic most. Concrete durability influence Air Content. Presently, We used to AE(air-entraining agent) for increase freeze-thaw durability. So, on concrete Air Spacing ratio used $200{\mu}m{\sim}230{\mu}m$ in Canada and under $250{\mu}m$ in Japan institution. Use of Air content has been and will continue to be a major part of concrete durability and scaling. Chloride-containing chemicals such as calcium chloride or rock salt are main deicers for the road. The prepared optimum mix concrete in this study show that freeze-thaw and scaling resistance of Non-AE(air content 1.5%) and AE (air content 4.5%, 7.2%). Solution concentrations of deicing agent were good result, and the pore system and change of hydration products is not difference comparing before freeze-thaw test.

• Food Science and Preservation
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• v.5 no.4
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• pp.331-334
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• 1998

Weight loss of table Grape packed with control(Corrugated paperboard box), LDPE, CE(MA film masterbatched by ceramic powder treated cemical reagent) and FC box(laminated by CE film pouch) at 25 C after 10 days were 5.6%, 0.4%, 0.6%, and 0.7%, respectively. Weight loss of control was 7.29times higher than that of FC box. Total ascorbic acid content(TAA) of table grape after 10 days was 3.42 mg% for control, was 5.33 for LDPE and 5.14mg% for CE, 4.98mg% for FC. TAA of LDPE and CE showed to higher than that of control, especially TAA of FC was 33% higher than that of control. Titratable acid of LDPE and CE was high compare to control, and acidity of FC was 6% higher than that of control. References in overall appearance of LDPE, CE and FC were better than that of control. Corrugated paperboard box(FC) laminated with functional MA film showed to be able to used as packaging box of table grape.

• KSBB Journal
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• v.19 no.6 s.89
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• pp.451-456
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• 2004

The effects of variation in composition of the medium on the conversion of Gluconacetobacter hanseii PJK cells producing cellulose ($Cel^+$) to non-cellulose producing ($Cel^-$) mutants and the production of bacterial cellulose (BC) in an agitated culture were investigated. The impeller speed greater than 500 rpm was required to decrease the population of $Cel^-$ mutants to minimum in a basal medium containing $1.5\%$ ethanol because the optimum impeller speed to minimize the population of $Cel^-$ mutants increased with the concentration of ethanol added to a basal medium. Ethanol fed-batch culture could not increase the BC production in an agitated culture unlike that of a shaking culture. The amount of BC produced in a basal medium containing $1\%$ ethanol was $39\%$ more than that of the same medium with $0.27\%\;Na_{2}HPO_4$. Increase in the concentration of acetic acid in a basal medium decreased the BC production. The pH control of the culture broth increased the cell mass in the batch culture and improved the production yield of water-soluble polysaccharide (WSPS), but did not affect the production of BC.

• Journal of the Korea Concrete Institute
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• v.14 no.1
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• pp.76-82
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• 2002

The rapid-set cement concrete causes high hydration temperature and nay result in a high drying shrinkage and shrinkage-induced cracking. This problem may be fixed by incorporating polypropylene fibers in rapid-set cement concrete, because of increased toughness, resistance to impact, corrosion, fatigue, and durability. A series of concrete drving shrinkage tests was peformed in order to investigate the shrinkage properties of polypropylene fiber reinforced concrete with experimental variables such as concrete types, fiber reinforcement, W/C ratio, with and without restraint. Uni-axially restrained bar specimens were used for the restrained shrinkage tests. The results were as follows; The dry shrinkage of rapid-set cement concrete was much lessor than that oi OPC, probably because of smaller weight reduction rate by early hydration and strength development. The constraint and bridging effects caused by polypropylene fibers were great for the rapid-setting cement concrete when compared with that of plain concrete, and this resulted In increased resistance against tensile stress and cracking.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.245-253
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• 2020

The present study is an experimental study to investigate the characteristics of strength by mixing polyaluminum chloride(PAC) with OPC-slag-FA ternary blended cement. There are three types of binders: 80% OPC + 10% slag + 10% FA, 60% OPC + 20% slag + 20% FA, and 40% OPC + 30% slag + 30% FA. PACs used 0, 2, 4, 6, 8, and 10% of the mixing-water weight. Experimental results show that PAC improves compressive strength regardless of the amount of OPC. PAC consumes portlandite, forms Friedel's salt, and reduces the diameter of the pores, making the matrix compact, contributing to the improvement of compressive strength. However, porous FA particles had an effect of delaying hydration by absorbing PAC in the initial hydration step. Therefore, the use of FA needs to determine the substitution rate in consideration of the hydration delay effect.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.4
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• pp.842-847
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• 2007

In this study, for the purpose of estimating the resisting moment of sloped ground based on level ground fall down safety equation in design specification, compute it depends on penetration depth of concrete pile applying modulus of foundation about the angle of internal friction, cohesion, unit weight of soil, classes of the ground, sandy or clay soil, and verify established study using L-Pile Plus13.8. Also, select four cases that characteristics of soil depending on the soil grade is considered and compute the 12m length concrete pile's resisting moment of the ground those angle is changing from $0^{\circ}{\sim}35^{\circ},\;step\;5^{\circ}$. In the result, identify that the resisting moment of ground decreases depending on ground slope. Thus, increasing of penetration depth is required.

• Resources Recycling
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• v.3 no.1
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• pp.38-43
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• 1994

The separation of valuable metals from IC chip scrap generated by domestic electronic company was carried out using the mechanical beneficiation such as shredding, crushing, screening and magnetic separation. The distribution of metals in various sizes of crushed IC chip scrap was investigated and metals present in crushed products was separated with the magnetic separator. The particle size distribution of crushed IC chip scrap was 7.5% for +3mm, 17.0% for 3~1mm and 75.5% for -1mm. The weight loss of crushed IC chip scrap was 18% when roasted at $700^{\circ}C$. The content of metals was 96% for +3~1mm, 13% for 1~0.595mm, 3.7% for 0.95~0.5. Au of 99% was present in -1mm crushed IC chip scrap. Ni, Fe, Cu, Sn and Pb were separated from crushed IC chip scrap by the magnetic separator under 700 and 2, 500 Gauss.

• Composites Research
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• v.35 no.4
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• pp.288-297
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• 2022

This study investigated the effect of addition of zirconia(zirconium oxide) powder on the curing behavior of phenolic resins. The heating rate controlled curing and isothermal curing behaviors of the phenol resin according to the content of the zirconia powder were analyzed. The viscosity and thermal decomposition characteristics of the phenolic resin with the zirconia content were also examind. From the DSC analysis, the degree of cure and the rate of cure were obtained. Finally, the activation energy for the cure reaction were calculated from the DSC data of the zirconia added phenolic resin. As a found, the higher the zirconia content, the longer the curing was delayed and the greater the activation energy required for curing. Additionally, the TGA result that as the content of zirconia increased, less weight loss was observed. The surface tackiness of the Carbon/Phenol prepreg was partially changed according to the zirconia content, but had no significant effect.