• Magazine of the Korea Concrete Institute
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• v.7 no.4
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• pp.149-156
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• 1995

The fracture process zone in concrete is a region ahead of a traction-free crack, in which two major mechanisms, microcracking and bridging, play important roles. The toughness due to bridging is dominant compared to toughness induced by microcracking, so that the bridging is dominani: mechanism governing the fracture process of concrete. Fracture mechanics does work for concrete provided that the fracture process zone is being considered, so that the development of model for the fracture process zone is most important to describe fracture phenomena in concrete. In this paper the bridging zone, which is a part of extended rnacrocrack with stresses transmitted by aggregates in concrete, is modelled by a Dugdale-Barenblatt type model with linear tension-softening curve. Two finite element techniques are shown for the analysis of progressive cracking in concrete based on the discrete crack approach: one with crack element, the other without crack element. The advantage of the technique with crack element is that it dees not need to update the mesh topology to follow the progressive cracking. Numerical results by the techniques are demonstrated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.909-916
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• 2013

Concrete containing lightly burnt MgO has long term expansibility. It also could compensate for the thermal shrinkage of mass concrete, because the hydration of MgO proceeds at a slow pace to long-term age. Thus, lightly burnt MgO has been applied to the construction of mass concrete such as dams. Recently, the expansion characteristics of MgO concrete with fly ash that could be applied to mass concrete for the reduction of hydration heat have been studied and however, limited studies on its durability. This study investigates the long-term durability characteristics of fly ash concrete with lightly burnt MgO. The durability tests on carbonation, freezing-thawing, diffusion of chloride, and resistance to sulfate attack were carried out for MgO concrete with curing for 360 days in submerged condition with different temperature of 20 and $50^{\circ}C$. The results reveal that MgO concrete shows a greater resistance of carbonation, diffusion of chloride, and resistance to sulfate attack. On the other hand the resistance of freezing-thawing was little influenced by MgO powder.

• Food Science and Preservation
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• v.20 no.1
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• pp.62-68
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• 2013

A fine granule was prepared using freeze-dried royal jelly. For its preparation, which depended on operational parameters like its glucose-to-total sugar content ratio ($X_1$,0-100%), ethanol concentration ($X_2$,75-95%) and sprayed ethanol solution content ($X_3$,8-12%) using freeze-dried royal jelly, the response surface methodology was used to monitor the optimum conditions for the yield, the fragmentation rate with shaking, and the organoleptic properties. The maximum yield was 89.99% with a glucose-to-total sugar content ratio of 59.30%, an ethanol concentration of 88.64%, and a sprayed ethanol solution content of 11.83%. The minimum fragmentation rate by shaking was 0.82% at the glucose-to-total-sugar content ratio of 22.35%, the ethanol concentration of 77.21%, and the sprayed ethanol solution content of 10.59%. The sensory score for the overall palatability of the organoleptic properties was 7.45 at the glucose-to-total-sugar content ratio of 31.81%, the ethanol concentration of 93.96%, and the sprayed ethanol solution content of 10.51%.

• Resources Recycling
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• v.15 no.4 s.72
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• pp.52-59
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• 2006

The purpose of this study was to evaluate the effects of ground granulated blast-furnace slag on strength development and durability of ordinary portland cement concrete (OPC) with steam curing types. Main experimental variables were slag contents(0%, 10%, 30%, 50%, 70%) and curing types (standard, accelerated curing). It were performed to check the basic properties of concretes that compressive strength, rapid chloride ion permeability and chemical resistance. From the result, we have found that increasing the amount of blast-furnace slag produced concrete with increased compressive strength and permeability resistance. Rapid freezing-thawing test showed that they were good enough to protect the concrete structures and to carry out cyclic freezing and thawing. The freeze-thaw resistance of blast-furnace slag produced concretes maintained above 90% of relative dynamic modulus after 300 freezing-thawing cycles. Increasing the amount of blast-furnace slag produced concretes with increased chemical resistance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.2
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• pp.67-74
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• 2008

This paper provides the test results of bonding behavior of the interface between concrete substrate and carbon fiber in the rehabilitation method applying carbon fiber with epoxy based resin adhesive. The difference in each components was gradually increased subjected to the repetition of temperature variation, regardless of the strength of the substrate concrete, while the ultrasonic interface between each component occurred. An increase in difference of the temperature resulted in a decrease in bond strength of each component. Associated failure mode was shown to be interfacial failure and substrate concrete failure. No remarkable changes were found in the deformation and ultrasonic velocity of each component until the four cycles of the dry and moisture test. Hence, the moisture condition may not affect the bonding behavior of each component. After the repetition of dry and moisture test, corresponding bond strength was reduced to 40% of that before test. For the effect of freeze and thaw test, the cycle of freeze and thaw within 4 cycles resulted in debonding of each component.

• Food Science and Preservation
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• v.23 no.2
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• pp.246-251
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• 2016

This study was performed to determine the effects of drying methods (HD, hot air drying; FD, freeze-drying) on the antioxidant and physiological abilities of Haw (Crataegus pinnatifida Bunge). Powder color values of dried Haw, L and b, were higher for HD, while the chroma values were higher for FD. The total polyphenol, and flavonoid contents of HD Haw and FD Haw were found to be $9.29{\pm}0.50mg\;GAE/mL$ and $15.48{\pm}0.38mg\;GAE/mL$, and $9.41{\pm}0.26mg\;RHE/mL$ and $26.46{\pm}0.34mg\;RHE/mL$, respectively. DPPH radical scavenging abilities at 100 mg/mL concentration were higher for FD (64.90%) than HD (28.66%), as were the reducing power, ABTS radical scavenging ability, and nitrite scavenging ability. However, the HMG-COA reductase of HD (74.67%) was higher than that of FD (72.10%). The ${\alpha}-glucosidase$ inhibitory abilities of HD and FD at a concentration of 0.1 mg/mL were 24.69% and 97.38%, respectively. These results indicate that Haw is a potential functional material and that freeze-drying Haw is better than hot air drying.

• Korean Journal of Poultry Science
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• v.14 no.2
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• pp.137-143
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• 1987

This study was carried out to compare the changes in the extractability, biological activity, and solubility of myofibrillar proteins and actomyosins during storage period at 4$^{\circ}C$ and -20$^{\circ}C$in pectoral. and leg muscle of broiler meat. 1. The results obtained are as fellows ; The extractabilities of myofibrillar proteins in pectoral and leg muscle were increased gradually to 7-days during storage at 4$^{\circ}C$ and decreased slightly during frozen storage at -20$^{\circ}C$. The extractabilities of actomyosins in pectoral and legmuscle were not greatly changed during cold storage and decreased gradually during frozen storage. 2. The Ca$\^$2+/-ATP ase activities of myofibrillar proteins in the both muscles were not greatly changed to 7-days during cold storage, and in the case of frozen storage, those were highest on the 2nd week, thereafter decreased with storage period. The Ca$\^$2+/-ATPase activities of actomyosins in pectoral and leg muscle were decreased sightly only frist day during cold storage and decreased gently during frozen storage. 3. Myofibrillar proteins in the both muscles were solubilized completely at 0.20M KCl in fresh meat, at 0.25M (pectoral) and 0.30M KCl (leg) in the cold storage, and at 0.30M KCl in the frozen storage. Actomyosins of both muscles were solubilized completely at 0.40M KCl in fresh meat, cold and frozen storage.

• Culinary science and hospitality research
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• v.17 no.2
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• pp.209-220
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• 2011

This research intends to research on the optimal cooking techniques by adding perilla leaves to raw noodles, in which it has various effects and functions in sterilization. The water content measured in the dough added with raw perilla leaf juice came out high as more perilla leaves were added. More freeze-dried perilla leaf powder decreased water content. The pH of the dough increased significantly as the added ingredients increased with significant differences among the samples. The chromaticity of the dough deliberately decreased in both a and b as the amount of raw perilla leaves in dough increased. The L value of raw noodles with freeze-dried perilla leaves tended to decrease as more ingredients were added. The result of the RVA analysis on the dough with raw perilla leaves showed that the gluten decreased with more raw perilla leaves added. The result of the RVA analysis on the dough with freeze-dried perilla leaf powder indicated that the initial pasting tempo tended to increase significantly with more powder added except for 5% and 7% of powder added with no significant difference. The values dropped as the freeze-dried powder was added Minimum viscosity tended to decrease definitely as more freeze-dried perilla leaf powder was added. The dough's measurement results of WRC showed that water absorbing power of both dough with raw perilla leaves and that with freeze-dried perilla leaf powder reduced significantly as more perilla leaf powder were added.

• Korean Journal of Food Science and Technology
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• v.34 no.5
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• pp.805-810
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• 2002

Development of tenderizer using domestic fruits was studied. Kiwifruit was dried using various methods, and the quality of kiwifruit powder was observed during 12 week storage. Frozen kiwifruit was prepared in paste, dice, and whole flesh. After drying, paste-type kiwifruit showed 2.0 and 1.3 times higher proteolytic activity than dice and whole flesh kiwifruits, respectively. Nine hour of hot-air drying or 46 h of freeze-drying eliminated more than 90% of water from kiwifruit, during which discoloring of kiwifruit occurred. Freeze-dried powder showed 6.6 times higher yield and proteolytic activity, and resulted in almost no discolorization than those of air-dried powder. Addition of bulking agent affected the quality of hot air-dried kiwifruit powder, except color, resulting in $3.2{\sim}3.6$ times higher proteolytic activity than that without bulking agent, which is comparable to 60% of the initial freeze-dried powder content. Moisture content of kiwifruit powder with bulking agent sustained consistently during 12 week storage, whereas proteolytic activity decreased for the first 4 weeks. Freeze-drying is a preferable method to produce kiwifruit powder for tenderizer, although hot air-drying with bulking agent treatment is more economical.

• Journal of the Korean Data and Information Science Society
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• v.27 no.1
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• pp.67-74
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• 2016

Due to the character of the climate of Korea, the pavement of a road is Influenced by freezing in winter season and thawing in thawing season. In the last few years, several articles have been devoted to the study to minimize the damage of freezing and thawing action. The purpose of this paper is to identify appropriacy of factors that influence road pavement thickness. We conduct the decision tree analysis on the field data of road pavement. The target variable is 'Frost penetration'. This value was calculated from the temperature data. The input variables are 'Region', 'Type of road pavement', 'Anti-frost layer', 'Month' and 'Air temperature'. The region was divided into 9 regions by freezing index $350{\sim}450^{\circ}C{\cdot}day$, $450{\sim}550^{\circ}C{\cdot}day$, $550{\sim}650^{\circ}C{\cdot}day$. The type of road pavement has three-section such as area of cutting, boundary area of cutting and bankin, lower area of banking. As the result, the variables that influence 'Frost penetration' are Month, followed by anti-frost layer, air temperature and region.