• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.2
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• pp.47-53
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• 2010

Very-early strength latex-modified concrete (VES-LMC) was developed with a focus on workability, strength development and long-term durability that would allow for opening a bridge to traffic only 3 hours after concrete placement, which would be useful when repairing concrete bridge deck overlays. However, even though usage of latex in VES-LMC improves the durability, it has a disadvantage that it produces lots of entrained air. Therefore, specific plan is necessary since it is weak for freezing and thawing in air-void structure. In the present study ultra-fine fly ash (UFFA) was used. Test results are follows ; Air content of VES-LMC UFFA (VES-LMC using UFFA) concrete was decreased since major pozzolan reaction was happened in one day. It was also found that total air content of concrete was decreased with pozzolan reaction since air content in 28 days was the same with one day air content. The addition of calcium hydroxide increased entrained air which is smaller than size of 200 ${\mu}m$. It was effective to improve the air-void structure of VES-LMC since spacing factor can be confirmed as smaller than size of 200 ${\mu}m$ using more than 15% of UFFA.

• Journal of Veterinary Clinics
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• v.28 no.1
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• pp.13-19
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• 2011

Semen cryopreservation induces the formation of reactive oxygen species (ROS), and the ROS cause sperm damage. We aimed to investigate the effects of the antioxidative enzyme catalase (CAT) on sperm quality and ROS during cryopreservation. Sperm rich fractions collected from five Duroc boars were cryopreserved in freezing extender with (200 or 400 U/mL) or without CAT (control). After thawing, sperm motility, viability, normal morphology, plasma membrane integrity, mitochondrial function and intracellular ROS were evaluated. CAT significantly improved total sperm motility at a concentration of 400 U/mL (P < 0.05), but didn't improve progressive sperm motility, viability, morphological defects, plasma membrane integrity and mitochondrial function in frozen-thawed boar sperm. In evaluation of ROS, CAT had no effect on reduction in ${\cdot}O_2$, but scavenged $H_2O_2$ in viable frozen-thawed boar sperm at concentrations of 200 and 400 U/mL (P < 0.05). In conclusion, CAT was not enough to improve quality of frozen-thawed sperm, but can reduce $H_2O_2$ generation in viable boar sperm during cryopreservation.

• Journal of the Korea Concrete Institute
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• v.15 no.4
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• pp.529-540
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• 2003

Recently, the researches on the durability design of concrete structures have been studied. As the examples, models to evaluate the service life prediction of the structure have been developed. The purpose of this article is to develop the model for predicting remaining service life. The final aim is to provide the user time for repairing the concrete structures. In addition, it makes possible to maintain the concrete structure economically. 70 reservoirs out of the inland concrete structures were selected and concrete structures of their components were surveyed. Two methods were used for measuring carbonation; TG/DTA method and Phenolphtalein indicator and, the value of pH was measured by the pH meter, After deriving correlations of calcium carbonate and used year, duration from completion year to 2002, pH value, and concrete cover depth the model was developed for predicting remaining service life by measuring data as small as possible. The conventional models had been developed on the basis of experiment data obtained from the restricted lab environment like as carbon gas exposure. On the other hand this model was developed on the basis of measuring data obtained from the real field that the complex deterioration actions are occurred such as freezing and thawing, carbonation, steel corrosion, and so on. The reliability of the developed model will be evaluated high in this point and this model can help to maintain concrete structures economically by providing the manager time to repair the deteriorated concrete structures in site of facility management.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.2
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• pp.246-253
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• 2012

In this study, we determined the optimum blanching conditions for pretreatment of Aster scaber prior to freezing to ensure its long, safe preservation as a fine cooking ingredient. Frozen-thawed A. scaber did not significantly differ between blanching groups, but the blanched group showed significantly higher Hunter L, a, and b values than the un-blanched group (p<0.05). Higher temperatures and longer treatment times increased softness; hardness did not significantly differ between the blanched and un-blanched groups of frozen-thawed A. scaber (p<0.05). Total bacterial counts and the presence of coliforms seemed to decline with blanching treatments, but treatment temperature and time did not influence this reduction. Over 95% of peroxidase activity was inactivated by blanching treatment but increased slightly after thawing. The sensory evaluation of the frozen-thawed A. scaber by test group showed the A. scaber blanched at $90^{\circ}C$ for 3 min to be the most highly preferred (p<0.05).

• Journal of Embryo Transfer
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• v.22 no.1
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• pp.21-26
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• 2007

본 연구는 mSOF(modified synthetic oviduct fluid medium) 배양액을 이용하여 $100{\mu}1$와 $10{\mu}1$ 배양 소적에서 일본 흑우의 수정란 생산 효율을 개선하기 위하여 수행하였다. 난구세포가 부착된 미성숙 난자는 각각 단독 배양조건($S;\;10{\mu}1$ 소적) 및 그룹 배양 조건 ($G;\;100{\mu}1$ 소적)에서 실시하였고 배양액은 TCM-199의 기본 배지에 10% FCS, 0.02IU/ml FSH와 $1{\mu}g/ml$ $estradiol-17{\beta}$를 첨가하여 사용하였다. 배반포 단계로 발육한 수정란은 1.5M ethylene glycol로 직접 이식법에 의한 동결 방법으로 동결을 실시하였고, 세포수는 융해 후 생존 수정란에 대해 조사하였다. 체외 배양 시간이 $16{\sim}17$시간 배양 조건에서 난자의 성숙율은 그룹 배양 조건$(27.1{\pm}16.8%)$보다는 단독 배양조건$(57.1{\pm}15.0%)$에서 성숙율이 높았다(p<0.05). 그러나 체외 배양 시간이 $18{\sim}19$ 시간과 $20{\sim}21$시간 배양시는 유사한 성숙율을 보였다. 난자의 체외 배양율은 체외 배양 시간의 증가에 의해 성숙도가 $86.3{\pm}9.9%$로 증가하였다. 접합체(zygote)의 분할율은 단독이나 그룹 배양 조건에서도 유사한 결과를 얻었다. 배반포 발달율은 배양 $7{\sim}8$일째에 조사한 결과 단독 배양 방법보다는 그룹 배양 방법에서 발달율이 높았으나, 분할된 접합체를 기준으로 한 경우 배반포 발달율$(S;\; 21.4{\pm}10.6%,\;G;\;39.0{\pm}13.1%)$에서는 유의적인 차이가 없었다. 단독 배양과 그룹 배양에서 $6.5{\pm}8$일 사이에 배반포로 발달된 수정란의 세포수 조사에서는 유사한 결과를 얻었다. 동결 융해 후 24시간 배양 후 배반포 생존율(5; 24.2%, G; 30.2%), 부화율(S: 20.9%, G: 12.7%) 및 생존 수정란수(S; 45.2%, G: 42.8%)에서도 배양 조건에 따른 유의적인 차는 없었다. 결론적으로 mSOF배양액을 이용하는 경우 미성숙 난자의 체외 성숙 유도 배양 시 단독이나 그룹 배양 시 배반포 발달율에서 그룹간에 유의적인 차가 인정되었다(p<0.01).

• Tunnel and Underground Space
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• v.19 no.2
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• pp.146-157
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• 2009

An experimental study of accelerated weathering on mudstone sample specimens from Haman, Gyeongnam was performed to investigate the variations of physico-mechanical properties of deteriorated rocks due to freeze-thaw weathering. Each complete cycle of freeze and thaw lasted 24 hours, comprising 2 hours of saturating in vacuum chamber, 8 hours of freezing at $-16{\pm}1^{\circ}C$ and 14 hours of thawing at room temperature. Total of 55 cycles of freeze-thaw were completed with measuring the index properties as well as geometries of microfractures. The measured specific gravity and P-wave velocity found to decrease with increasing freeze-thaw cycles. On the other hand, absorption ratio and effective porosity were continuously increased with increasing freeze-thaw cycles. It was found that the index properties of deteriorated sample specimen depend on its initial properties and flaws in rock. The size and density of the traces of the microfracture on slab specimen exhibited abrupt changes after 30 cycles of freeze-thaw weathering. The results obtained in this study show that the box fractal dimension($D_B$) given in this paper has the strong capability of quantifying the size and density of the microfracture.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.5
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• pp.731-737
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• 2011

TMR (total mixed ration) feed was developed by adding mugwort (Artemisia capillaris Thunb.) and was fed to Hanwoo cattle. We investigated the effects of feeding mugwort on the physicochemical properties and sensory scores of the Hanwoo beef, as well as the feasibility of producing beef with high quality and function. Samples included Hanwoo loin fed with fattening cattle TMR feed with (treatment) or without mugwort (control). The content of total catechin in Hanwoo loin fed with the treatment and control was 0.516 and 0.307 mg/kg, respectively, while the content of epicatechin was 0.116 and 0.087 mg/kg, respectively, both of which were significant increase from feeding TMR with mugwort (p<0.05). There was no significant difference between the control and treatment in terms of $b^*$ value, VBN content, EDA, total bacterial numbers, freezing loss, thawing loss, cooking loss, hardness, cohesiveness, gumminess, chewiness, shear force, or sensory score of boiled meat. $L^*$, $a^*$ and pH value for the treatment were significantly higher than the control (p<0.05). TBARS and springiness for the control were significantly higher than the treatment (p<0.05). The aroma of the raw meat and the taste, tenderness, juiciness, and palatability of the roasted meat for the treatment were significantly superior to the control (p<0.05). These results suggest that giving feed containing mugwort inhibits lipid oxidation, increases water holding capacity, and improve sensory scores.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.3
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• pp.261-267
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• 2015

To develop high-strength high-volume ground granulated blast-furnace slag (GGBFS) concrete, this study investigated the characteristics of strength development and durability of concrete with the water-to-binder ratio of 23% and the GGBFS replacement ratio of up to 65%. The results show that the compressive strength of GGBFS blended concrete is lower than that of ordinary Portland cement (OPC) concrete up to 3-day age, but the becomes higher after 7-day age. Together with strength increase, the pore structure becomes tighter, and thus the resistance to chloride ion penetration increases. Therefore, the GGBFS blended concrete has high resistance to freezing and thawing without additional air-entraining, and high resistance to carbonation despite low amount of calcium hydroxide ($Ca(OH)_2$). On the other hand, if silica fume (SF) is blended with GGBFS, the strength becomes lower than that of the concrete blended with GGBFS only, and the resistance to chloride ion penetration deceases. Therefore, it needs further studies on the reaction of SF in high-strength high-volume GGBFS concrete.

• Journal of the Korea Concrete Institute
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• v.13 no.4
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• pp.329-335
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• 2001

Recently, in many laboratories and institutes it is being studied on the high flowing concrete widely, which has high fluidity, non-segregation ability and fillingability, and sometimes being applied to the construction field actually. And the fluidity properties of high flowing concrete are influenced according to the several factors ; binder content, water/binder ratio and water content etc. This is an experimental study to compare and analyze the effect of water/binder ratio and water content on the properties of high flowing concrete. For this purpose, the mix proportion of high flowing concrete according to water/binder ratio(W/B : 0.30, 0.35, 0.40, 0.45) and water content (W : 155, 165, 175, 185 kg/㎥) was selected. And then slump-flow, V-lot, L-passing test in fresh concrete, and compressive strength, freezing and thawing test in hardened concrete were peformed. According to test results, it was found that the viscosity of all those high flowing concrete with the water content 175 kg/㎥ was satisfied with 50 cm pass time of slump flow prescribed by Japanese Architectural Standard Specification (JASS 5) - from 3 to 8 seconds. And non-segregation ability of concrete with W/B 0.35 was better than the other mix proportions. Especially, the compressive strength after curing 24 hours(1 day) of all high flowing concrete was higher than that prescribed by JASS 5(50 kgf/㎠).

• Magazine of the Korean Society of Agricultural Engineers
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• v.27 no.2
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• pp.57-71
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• 1985

The characteristics of compaction and unconfined compressive strength were investigated by mixing with lime to all soils adjusted by given percentages of two kinds of clays to sand to obtain the most effective distribution of grain size and the optimum lime content for soil stabilization. In addition, unconfined compressive strength and durability tested by adding of sodium metasilicate, sodium sulfate, sodium carbonate, sodium gydroxide and magnesium oxide to lime-soil mixture mixed with 8 percent lime to adjusted soil having the mixing percentage of 60 percent of cohesive black clay and 40 percent of sand by weight to get the effect and the optimum content of chemicals. The results obtained were as follows; 1.With the addition of more lime, the optimum moisture content was increased, and the maximum dry density was decreased, whereas the more the amount of clay and the less was the maximum drt density. 2. In the soil having more fine grain size the unconfined compressive strength was larger in the earlier stage of curing period, in accordance with the longer period, the mixing percentages of sand to clay showing the maximum unconfined compressive strength, on the basis of 28-day strength, were 60% : 40% (black clay) and 40% : 60% (brown clay) respectively. 3. The reason why the soil adjusted with black clay was remarkably bigger in the unconfined compressive strength than ones adjusted with brown clay for all specimen of lime-soil mixture was the difference in the kind of clay, the amount of chemical compositions the value of pH. Black clay was mainly composed of halloysite that reacted with lime satisfactorily, whereas the main composition of brown clay was kaolinite that was less effect in the enhance of unconfined compressive strength. Also the difference of unconfined compressive strength was because black clay was larger in the amount of composition of calcium oxide and magnesium oxide in the value of pH affecting directly on the unconfined compressive strength of lime-soil mixture than brown clay. 4. In the lime-soil mixture mixed with 8 percent of lime to soil that mixing percentage of sand to black clay was 60% : 40%, on the standard of 7-day strength, the effect of chemical was arranged in the order of magnesium oxide, sodium carbonate, sodium sulfate, sodium hydroxide and sodium metasilicate. 5. The optimum amount of chemical being applicable to the maximum unconfined compressive strength of lime-chemical-soil mixture was 1 percent by weight for air dry soil in the case of adding sodium carbonated and 0.75 percent on sodium hydroxide, the unconfined compressive strength was increased continuously with increase of the amount of chemical up to 2 percent of chemical content is the lime-chemical-soil mixture added sodium metasilicate, sodium sulfate and magnesium oxide. 6. It was considered that the chemical played and accelerant role of early revelation of strength because the rate of increase of unconfined compressive strength of all of lime-chemical-soil mixtures was largest on the 7-day cured specimen. 7. The effect of test on freezing and thawing after adding suitable amount of chemical on the lime-soil mixture mixed with 8 percent of lime to soil that mixing percentage of sand to black clay was 60% : 40% was arranged in the order of magnesium oxide, sodium carbonate, sodium sulfate, sodium metasilicate and sodium hydroxide.