• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 추계 학술논문 발표대회
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• pp.13-14
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• 2016

In the modern construction industry, since numerous skyscrapers have been built, there have been sought for developing various kinds of methods for shortening a construction period. Therefore, many kinds of studies on some kinds of cold-weather concrete have been conducted actively for the purpose of a year-round construction. Accordingly, this research team once developed a double-layered bubble sheet as a surface-coated curing material for winter. And there have been raised some worries that some initial damages to frozen concrete caused by low temperature of reinforcing bars which are exposed out of the wall areas of a wall-type apartment during winter. Therefore, in this study, it is intended to find out clearly whether it is possible for concrete to be damaged initially or not by analyzing the temperature characteristics of the exposed reinforcing bars of the wall areas under the temperature conditions during winter.

• 한국세라믹학회지
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• 제29권8호
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• pp.587-592
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• 1992

Sheets of SiC-SiC whisker maxed matrix were prepared from the mixed slurry of SiC whisker and SiC matrix by the rolling method. With the increase of SiC whisker, the pore size, the porosity and the phosphoric acid absorbency of the matrix were increased, while the bubble pressure was decreased. The activation energy for the transfer of H+ ion was decreased with the increase of mixing ratio of SiC whisker to the SiC matrix from the measurement of hydrogen ion conductivity. The activation energy was evaluated as 0.25 eV when the mixing ratio of SiC whisker to the SiC matrix was 1 : 2 and the activation energy was 0.16 eV for the 2 : 1 matrix. It means that SiC whisker matrix contributes to attain a better microstructure for the diffusion of hydrogen ion. From the measurement of single cell performance of matrix with various mixing ratio, it is concluded that if SiC-SiC whisker maxed matrix has a sufficient bubble pressure to prevent the crossover of H2 gas, the current density of a fuel cell is increased with the increase of acid absorbency of the matrix. Current density was improved from 140 mA/$\textrm{cm}^2$ for 0.25 mm thickness of matrix to 170 mA/$\textrm{cm}^2$ for the 0.20 mm one at 700 mV.

• 대한방사선기술학회지:방사선기술과학
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• 제20권1호
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• pp.39-42
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• 1997

This study was done at 45 medical facilities located in Seoul. The purpose of study is twofold. First, this is to investigate usually who extmines patients for UGI and how many films are used for the examination. Secondly, this is to evaluate image qualities of UGI in terms of representation of lesser curvatures, amount of Ba and air and other criteria for the exam. The results are as follows : 1. In most cases, the UGI is examined by the Dr(67%), by the RT(22%), and together(11%). 2. The total films used ranged from 5 sheets(42%) to 7 sheets(18%). 3. The amount of Ba given to Pt. was mostly $200{\sim}300\;ml$(60%) and gastrografin was used $3{\sim}4\;g$(86.6%) for the examination. 4. For the evaluation of qualities, lack of representation of lesser curvature was 86.7%, lack of Ba and air and bubble formation was 62%, 46.7% and 42.2% respectively.

• 대한조선학회논문집
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• 제59권6호
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• pp.355-361
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• 2022

In order to produce model ice sheets having targeted physical properties in accordance with the law of similitude, the ice model basin of Korea Research Institute of Ships and Ocean Engineering carries out a series of processes such as cooling, seeding, freezing, and tempering. Performance in ice field of ice going ships or marine structures is evaluated from model tests in ice conditions made out of a model ice sheet such as level ice, pack ice, brash ice, and ice rubble field, etc. In this study, we investigated effects of micro-bubble layers and seeding of ice nuclei included in the process generating a model ice sheet on change in physical properties of thickness, density, and flexural strength.