• Fire Science and Engineering
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• v.29 no.6
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• pp.109-118
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• 2015

Recently, three kinds of search robot prototypes were developed to assume the role of fire fighters for search and rescue missions in special disaster areas with high heat, smoke, toxic gases, or radioactivity. To accomplish search missions, these robots should be able to endure heat, overcome various obstacles, suppress fires, and see through dense smoke. This study investigated the heat resistance, practicality, and fire fighting capacity of these robots. The results show that the small and middle-sized robots were resistant to surrounding temperatures of $100{\sim}200^{\circ}C$, and the fire-fighter-riding robot could endure up to $500^{\circ}C$ for half an hour. The fire-fighter-riding robot showed excellent extinguishing performance on an A-10 class fire model, which was extinguished within 3 min. The robots also showed various capacities for overcoming obstacles and are expected to play an active role in various special disaster areas.

• Korean Journal of Environmental Agriculture
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• v.27 no.4
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• pp.389-394
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• 2008

The ecophysiological changes occurring upon cold stress were studied using cold tolerant transgenic and wild-type tobacco plants. In a previous study, cold tolerance in tobacco was induced by the introduction of a gene encoding the zinc finger transcription factor, PIF1. Gas-exchange measurements including net photosynthesis and stomatal conductance were performed prior to, in the middle of, and after a cold-stress treatment of $1{\pm}2^{\circ}C$ for 96 h in each of the four seasons. In both transgenic and wild-type plants, gas-exchange parameters were severely decreased in the middle of the cold treatment, but had recovered after 2-3 h of adaptation in a greenhouse. Most t-test comparisons on gas-exchange measurements between the two plant types did not show statistical significance. Wild-type plants had slightly more water-soaked damage on the leaves than the transgenic plants. A light-response curve did not show any differences between the two plant types. However, the curve for assimilation-internal $CO_2$ in wild-type plants showed a much higher slope than that of the PIF1 transgenic plants. This means that the wild-type plant is more capable of regenerating Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and has greater electron transport capacity. In conclusion, cold-resistant transgenic tobacco plants demonstrated a better recovery of net photosynthesis and stomatal conductance after cold-stress treatment compared to wild-type plants, but the ecophysiological recoveries of the transgenic plants were not statistically significant.

• Korean Journal of Food Science and Technology
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• v.30 no.1
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• pp.97-102
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• 1998

Arrowroot starches, harvested in March, June, September and December, indicated that the December starch had the lower values of amylose content, ${\beta}-amylolysis$ limit and intrinsic viscosity, but the highest value of water-binding capacity. The swelling power were similar among different starches. The gelatinization by KSCN revealed that the December starch was the most resistant to alkali gelatinization. Gelatinization temperature, determined by differential scanning calorimetry, of the December sample was shifted to higher temperture by $1^{\circ}C$ compared with the others. When the December starch was heated at $98^{\circ}C$ for 8min, 93.8% of total amylose and 7.2% of total amylopectin were solubilized, which was the highest and the lowest, respectively.

• Clinical and Experimental Reproductive Medicine
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• v.20 no.1
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• pp.31-36
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• 1993

The effects of freezing and 1,2-propanediol on early and late pronucleate stage mouse ova were investigated in terms of survival after thawing and development in vitro. The samples were divided into two groups according to different age in pronucleate ova: ova in(1) early pronuclear stage with two distant pronuclei at 18h after hCG injection, and (2) late pronuclear stage with adjacent pronuclei at 30h. Zygotes in the late pronuclear stage have been proven to be more resistant to 1,2-propanediol, showing a significantly higher developmental rate than zygotes in early stage (80.3 versus 66.3%, <0.05), but survival rate was similar in the two groups (91.0 versus 93.5%). After freezing and thawing, survival and developmental rates were decreased in both groups when compared to the control group (54.3 versus 92.3%, 47.7 versus 73.3%. respectively). And developmental rate in the late pronuclear stage zygotes showed significantly higher than in early (55.4 versus 40.0%) after thawing. In conclusion, early pronucleate mouse ova have a lower developmental capacity in vitro and a lower survival rate after freezing and thawing than late ova. These findings suggest that the timing of freezing could be important for survival and further development in vitro in cryopreservation of human pronucleate ova.

• Solar Energy
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• v.20 no.2
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• pp.75-84
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• 2000

Global wanning induced by greenhouse gases such as carbon dioxide is a serious problem for mankind. Carbon dioxide ocean disposal is one of the promising options to reduce carbon dioxide concentration in the atmosphere because the ocean has vast capacity for carbon dioxide sequestration. However, the dissolution rate of liquid carbon dioxide in seawater must be known in advance in order to estimate the amount of carbon dioxide sequestration in the ocean. Therefore, the solubility, the surface concentration, the droplet size and other factors of liquid carbon dioxide at various depths are calculated. The results show that liquid carbon dioxide changes to carbon dioxide bubble around 500 m in depth, and the droplet is completely dissolved below 500 m in depth if carbon dioxide droplet is released both at 1000 m in depth with the initial droplet diameter of 0.011 m or less and at 1500 m in depth with the diameter of 0.015 m or less. In addition, the hydrate film acts as a resistant layer for the dissolution of liquid carbon dioxide. The surface concentration of carbon dioxide droplet with the hydrate film is about 50% at 1500 m in depth and about 60% at 1000 m in depth of the carbon dioxide solubility. Also, the ambient carbon dioxide concentration in the plume is an another crucial parameter for complete dissolution at the intermediate ocean depth, and the injection of liquid carbon dioxide from a moving ship is more effective than that from a fixed pipeline.

• Aerospace Engineering and Technology
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• v.1 no.1
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• pp.147-152
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• 2002

In the preceding tests of Sub.(Ⅰ) engines, it was observed that the heat resistant capability of the engines was not enough, and the design of Sub.(Ⅰ) engines was modified to satisfy the mission requirement. Sub.(Ⅰ) Mod. engines have three major design parameters - the arrangement of main injectors, the impinging angle of main injectors and thermal barrier coating. More than 20 experiments were carried out to evaluate engine performance and heat resistance capability with respect to design parameters. Analysing the result of Sub.(Ⅰ) and Sub.(Ⅰ) Mod. engine tests, it is found that the decreased impinging angle, adopting the H-type arrangement(rather than radial type arrangement), and adopting the thermal barrier coating can increase heat resistance capacity substantially. The result show that the performance variation by design change is below 5 percents and the radial type arrangement of injectors has higher performance than H-type. However, the performance of 15°impinging angle engine is higher than that of 20°impinging angle engine, which is inconsistent to our expectation. High frequency instabilities may cause such phenomenon, which will be verified by a series of tests.

• Food Science of Animal Resources
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• v.41 no.6
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• pp.967-982
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• 2021

Probiotics are living microorganisms that, when administered in adequate amounts, provide a health benefit to the host and are considered safe. Most probiotic strains that are beneficial to human health are included in the "Lactic acid bacteria" (LAB) group. The positive effects of probiotic bacteria on the host's health are species-specific and even strain-specific. Therefore, evaluating the probiotic potential of both wild and novel strains is essential. In this study, the probiotic characteristics of Lactobacillus brevis KT38-3 were determined. The strain identification was achieved by 16S rRNA sequencing. API-ZYM test kits were used to determine the enzymatic capacity of the strain. L. brevis KT38-3 was able to survive in conditions with a broad pH range (pH 2-7), range of bile salts (0.3%-1%) and conditions that simulated gastric juice and intestinal juice. The percentage of autoaggregation (59.4%), coaggregation with E. coli O157:H7 (37.4%) and hydrophobicity were determined to be 51.1%, 47.4%, and 52.7%, respectively. L. brevis KT38-3 produced β-galactosidase enzymes and was able ferment lactose. In addition, this strain was capable of producing antimicrobial peptides against the bacteria tested, including methicillin and/or vancomycin-resistant bacteria. The cell-free supernatants of the strain had high antioxidant activities (DPPH: 54.9% and ABTS: 48.7%). Therefore, considering these many essential in vitro probiotic properties, L. brevis KT38-3 has the potential to be used as a probiotic supplement. Supporting these findings with in vivo experiments to evaluate the potential health benefits will be the subject of our future work.

• Journal of Plant Biotechnology
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• v.48 no.4
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• pp.246-254
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• 2021

Environmental stresses are estimated to have reduced global crop yields of wheat by 5.5%. However, traditional approaches for the transfer of resistance to these stresses in wheat plants have yielded limited results. In this regard, genetic transformation has undoubtedly opened up new avenues to overcome crop losses due to various abiotic stresses. Particle bombardment has been successfully employed for obtaining transgenic wheat. However, most of these procedures employ immature embryos, which are not available throughout the year. Therefore, the present investigation utilized mature seeds as the starting material and used the calli raised from three Moroccan durum wheat varieties as the target tissue for genetic transformation by the biolistic approach. The pANIC-5E plasmid containing the SINA gene for drought and salinity tolerance was used for genetic transformation. To enhance the regeneration capacity and transformation efficiency of the tested genotypes, the study compared the effect of copper supplementation in the induction medium (up to 5 μM) with the standard MS medium. The results show that the genotypes displayed different sensitivities to CuSO₄, indicating that the transformation efficiency was highly genotype-dependent. The integration of transgenes in the T₀ transformants was demonstrated by polymerase chain reaction (PCR) analysis of the obtained resistant plantlets with primers specific to the SINA gene. Among the three genotypes studied, 'Isly' showed the highest efficiency of 9.75%, followed by 'Amria' with 1.25% and 'Chaoui' with 1%.

• Journal of the Korean Society of Safety
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• v.34 no.3
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• pp.96-101
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• 2019

Chemicals Control Act have been strengthened to control more safely hazardous chemicals from 2015. In particular, the standards for the installation and management of handling facilities was enhanced with specific regulations depending on type of the facilities and the hazardous chemicals. However, some standards for handling facilities caused difficulties in implementing the strengthened standards due to various field conditions, such as lack of physical space. The Ministry of Environment is implementing Safety Assessment System (SAS) to solve these problems since 2018. However, many plants have difficulties in preparing alternative methods to pass the safety evaluation. The purpose of this study was to review and analyze the SAS and to suggest alternative measures in terms of management and technical aspects through the case study of hydrochloric acid storage tanks. The following safety solutions were suggested for handling facilities that had insufficient the space and capacity for the retaining wall due to physical space. Firstly, insufficient space was resolved by introducing equipment relocation or demolition, and retaining wall expansion. Secondly, the wall of the surrounding buildings was used as an alternative to the retaining wall with additional chemical resistant treatment. Finally, sensor installation and facility inspection were suggested as ways to improve chemical safety. Therefore, improvement of chemical accident prevention system is required not only in terms of facilities supplementation but also management aspect. The results of this study are expected to be available for similar facilities and will be based on the preparation of additional safety assessment as alternatives measures in the future.

• Journal of the Korea Safety Management & Science
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• v.21 no.1
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• pp.1-7
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• 2019

Along with industrial development, various architectural structures have become bigger and higher, leading to an expansion in the size and capacity of construction equipment. And with the development of public transportation, the use of subways as a means of transportation in the city center is increasing, so that vibrations and structural noises are emerging as a new environmental issue. Considering that architectural structures may be used from several decades to hundreds of years after the time of construction, they can be seen as semi-permanent. Due to changes in the vibration-proof polyurethane mats installed in the foundation of these structures, settling may occur and vibration reduction may become inadequate. Therefore, in view of service life, it is necessary to have a high-level standard of reliability and stability. In accordance with this, the Floating Floor System, which uses soft polyurethane foam and can be constructed within a relatively short period of time, has excellent vibration resistant characteristics. It is presented as a great alternative solution to the issue of vibrations caused by subways, railways and building structures. At present, vibration-proof polyurethane mats have been developed up to the same product level as in other advanced countries. However, in the construction of structure foundations, the physical properties of this product and its shape incur changes. If they are installed as such in the structure of a building, it may cause significant impact on stability, requiring that this cause be urgently identified and improved.