• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.2
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• pp.117-123
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• 2013

As fiber reinforced polymer (FRP) material is appled for a curved structure such as tunnel, FRP material must has a curved shape. Until now, the curved FRP material has been producted by hand-lay-up or filament winding work. It is impossible for mass production of the curved FRP material by these methods. Also, the quality of product by these methods is lower than that by pultrusion method. New pultrusion method and equipment had been developed for production of FRP material with steady curvature. The objective of this study is to evaluate the effect of freezing and thawing on adhesion of cement concrete with coarse-sand coated FRP in repair and reinforcement of cement-concrete structure using curved FRP material.

• Korean Journal of Food Science and Technology
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• v.28 no.1
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• pp.109-116
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• 1996

The relationship between antioxidant activities and physicochemical properties of several fractions obtained from freeze-dried (FD) coffee were investigated. The nine kinds of fraction were consecutively extracted from FD coffee with solvents in increasing order of polarity, and the higher polarity of the solvent the higher extraction yield of the fraction. The antioxidant activities of the fractions were determined by Rancimat and oven test on edible oils. The antioxidant activities of the fractions increased in the order of acetone>ethanol>methanol>50% methanol/water>water fraction, and the antioxidant activities of them were higher on lard than on soybean oil. The antioxidant activity of each fraction was strongly related to the contents of total phenol, total nitrogen content and acidity, whereas color intensity, reducing power, carboxylic acid content showed little contribution to the activity. All fractions had three peaks maxima at 208, 275 and 324 nm on UV-visible spectra, but the only one at 324 nm was linealy proportional to the antioxidant activities of the fractions.

• Journal of the Korean GEO-environmental Society
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• v.15 no.5
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• pp.47-56
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• 2014

In winter season, the pore water inside the ground freezes and thaws repetitively due to the cold air temperature. When the freezing-thawing processes are repeated on the ground, the change in soil particle structure occurs and thus the damage of the infrastructure may be following. This study was performed in order to investigate the stiffness change of soils due to the freeze-thaw by using elastic waves. Sand-silt mixtures are prepared with in the silt fraction of 40 %, 60 % and 80 % in weight and in the degree of saturation of 40 %. The specimens are placed into the square freezing-thawing cell by the temping method. For the measurement of the elastic waves, a pair of the bender elements and a pair of piezo disk elements are installed on the cell, and a thermocouple is inserted into soils for the measurement of the temperature. The temperature of the mixtures is decreased from $20^{\circ}C$ to $-10^{\circ}C$ during freezing, is maintained at $-20^{\circ}C$ for 18 hours, is gradually increased up to the room temperature of $20^{\circ}C$ to thaw the specimens. The shear waves, the compressional waves and the temperature are measured during the freeze-thaw process. The experimental result indicates that the shear and the compressional wave velocities after thawing are smaller than those of before freezing. The velocity ratio of after thawing to before freezing of shear wave is smaller than that of the compressional wave. As silt fraction increases from 40 % to 80 %, the shear and compressional wave velocities are gradually increased. This study suggests that the freezing-thawing process in unsaturated soil loosens the soil particle structure, and the shear wave velocity reflects the effect of freezing-thawing more sensitively than the compressional wave velocity.

• Journal of Plant Biotechnology
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• v.45 no.4
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• pp.400-408
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• 2018

Biodiversity has continued to degrade in the $21^{st}$ century due to global warming occasioned by destruction of the environment around the world.. The Nagoya protocol places Korea in a unique position to effectively develop and protect its domestic genetic resources. Microalgae under study in this research contains large amount of antioxidant substances such as beta carotene and astaxanthin, that can be used as biological resource owing to the large amounts of biomass that can be secured through photosynthesis. However, it is difficult to preserve it since cryopreservation method used for long-term preservation is yet to be developed. A basic study for long term cryopreservation was carried out on Nizschia frustulum and Nitzschia amabilis which belong to marine diatoms. As cryoprotectants (CPAs), glycerol, DMSO, and methanol which penetrate into cells were prepared at 5%, 10%, and 15% concentrations each, in case of methanol, it was tested at concentrations of 5%, 10% and 12% by its nature. Two kinds of microalgae, N. frustulum and N. amabilis, were diluted with $10^2$, $10^3$ and $10^4cells\;ml^{-1}$, respectively. The highest survival rate was shown at12% concentration of methanol, and the figures were $6.94{\pm}0.31%$ in N. frustulum and $8.85{\pm}0.16%$ in N. amabilis. As a result of 3 weeks cultivation of thawed microalgae after freezing, the result is shows that N. frustulum increased about 10 times faster and N. amabilis increased about 12 times the original concentration.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2007.11a
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• pp.173.1-173.1
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• 2007

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 1996.06a
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• pp.59-59
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• 1996

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2001.06a
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• pp.77-77
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• 2001

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.1030-1038
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• 2010

In order to design and construction of the Antarctic Continental Station at the Terra Nova Bay in the East Antarctic, ground characteristics for soil samples taken from the Antarctic. A series of laboratory tests were performed to investigate the variations of the thermal conductivity, the unfrozen water content according to the temperature change of the soil taken from the Antarctic. The temperature were low down below zero.

• Journal of Power System Engineering
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• v.15 no.4
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• pp.42-47
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• 2011

The purpose of this study is to investigate the best melting condition with various winding number of a heating pipe, supplying quantity of engine coolant and coolant temperature at the inlet of the heating pipe. Also, it is to suggest getting method of an appropriate quantity of the agent for the urea-SCR system within 10 minutes. For this matter, this study identifies the temperature distribution of inside of urea-tank while it is frozen at the low temperature condition, and suggests the best melting condition of the frozen urea within 10 minutes. From the results, it was found that 2L of melted urea was obtained by the coolant flow rate of 200L/hr at $70^{\circ}C$ for 10 minutes from the start of engine operating.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.287-288
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• 2010

The purpose of this study aimed to evaluate properties of water resistance, disease of freezing and thawing and XRF of Loess mortar using non-cement binder to solve reduction of durability by freezing and thawing on exiting Loess bicycle load.