• Journal of the Korea Institute of Building Construction
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• v.14 no.4
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• pp.308-313
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• 2014

Recently, for longevity of resident building, the main trend is that the change of the inside space organization of resident building from wall construction to rhamen construction, which resulted in increase in use of lightweight composite panel. Thus, in this study, authors analyzed the engineering property of oxide of magnesium depending on the magnesium chloride addition ratio. The results of this research is expected to contribute on providing a fundamental material for the surface materials of lightweight composite panel. As the result of the experiment, as fluidity increased, air content decreased and initial set and final set as the magnesium chloride addition ratio increase. In the aspect of flexural strength and compressive strength, the test specimen showed the highest strength at 40% of the magnesium chloride addition ratio. At 20% of the magnesium chloride addition ratio, the test specimen showed the lowest water absorption rate. As the magnesium chloride addition ratio increases, the expansibility tends to increase as well in the aspect of shrinkage strain. After observing microstructure, we can see hydration products in the form of needle. It appeared high flexural strength because the hydration products have mineral fibrous tissue shape, which also contribute to the cause of the expansibility.

• Journal of the Society of Disaster Information
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• v.9 no.3
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• pp.315-323
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• 2013

Recently, FRB is being used more as reinforcement of RC beam thanks to its material advantages in construction industry. The external attachment reinforcement of FRP is a construction method with advantages such as high strength, stiffness, excellent durability and construction practicability, despite of its weight. However, the reinforcement has a disadvantage to cause damage on permanent structure as its structure is water-tight by low water permeability reinforcement, preventing water from draining outside. The study attempted flexural failure test for GP of which material properties are equally same as the existing FRP and that with permeability, shows good binding with the concrete structure, durable performance and durability, comparably analyzing the improvement of durability and ductility according to changes of fiber contents of composite strip.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.11
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• pp.458-465
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• 2016

The purpose of this research is to improve the thermal effiency of solar collector and to quantitatively analyze its performance. Solar thermal systems have been limited to water heating systems mainly using low-temperature range. However, through diverse developments, the application has been extended to medium- and high-temperature fields such as solar heating, solar air conditioning, and solar thermal industrial process. Among the diverse research, this research is specially focusing on enhancement of the thermal performance by minimizing the heat loss coefficient of flat plate solar collectors. In order to do it, a front-side glazing material and a back-side insulation material with high insulated structure is proposed and based on computational analysis, the performance of energy collecting volume of the proposed solar collector is analyzed. The research shows that the proposed structure has the excellent performance at medium- and high-temperature range. therefore, it is expected that the proposed structure can easily replace existing technologies.

• Journal of Digital Convergence
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• v.17 no.12
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• pp.13-22
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• 2019

The purpose of this study is to examine the effects of child interaction, marital conflict and social support on the career-interrupted women's parenting stress and to investigate the mediating effects of marital conflict between child interaction and parenting stress. The data of 8th Panel Study on Korean Children was used for this, and it was conducted descriptive statistics, correlation analysis, and multiple regression analysis on the data of 868 career-interrupted women. According to the analysis, the factors affecting career-interrupted women's parenting stress are the child interaction, marital conflict, and social support, and it showed 32.3% of explanatory power and the influence of marital conflict was the highest. It was also found that marital conflicts were partially mediated in the relation with the child interaction and parenting stress. Based on this, this study suggests the policy and practical measures to prevent and reduce their parenting stress in view of supporting the career-interrupted women's reentry of labor market in the era of work-family balance.

• Journal of the Society of Disaster Information
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• v.8 no.4
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• pp.391-400
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• 2012

Recently, the construction industry commonly uses FRP as a reinforcement material because of its material advantages. FRP attached reinforcement has various advantages such as high strength, stiffness, excellent durability and construction practicability comparing to its weight. However, external attachment of FRP is water-tighted with low water permeable material, not draining water, probably causing damages on a permanent structure. The study manufactured it through pultrusion and examined GP(glass fiber panel) of which material-mechanical properties are almost same as the existing FRP but durability and attachment performance are better by stationary experiments, testing load-deflection curve, destruction types and load-deflection relation under repetitive loading test. As a result of 2,000,000 fatigue tests, it did not result in the destruction and showed excellent permanent attachment and durability as it displays significantly low compressive strain of concrete.

• Journal of Bio-Environment Control
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• v.22 no.2
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• pp.167-174
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• 2013

Six kinds of sprout vegetables were applied three and six types of non-perforated breathable propylene films (NPB film) for individual and mixed modified atmosphere (MA) package condition at $10^{\circ}C$ on this study. As a tah tasai, kohlrabi, rape, chinese cabbage, red radish, broccoli sprouts were packaged by 20,000, 60,000, and 100,000 $cc{\cdot}m^{-2}{\cdot}day{\cdot}atm$ non-perforated breathable films for seven days storage. Mixed sprout vegetables were used 20,000 cc, 40,000 cc, 60,000 cc, 80,000 cc, and 100,000 $cc{\cdot}m^{-2}{\cdot}day{\cdot}atm$ non-perforated breathable films for seven days storage. Loss rate of fresh weight, changes of carbon dioxide, oxygen, and ethylene gas concentration were measured during the storage. Visual quality and off-flavor were rated by panel tests after seven days storage. Each sprout vegetable storage with film tests had been shown under the 0.5% fresh weight loss in every packaged films, and the 20,000cc NPB film package had been suitable atmosphere condition in the carbon dioxide and oxygen gas concentration. Appearance and off-odor of sprouts packaged with 20,000cc NPB film were shown better than other films because of the proper gas movement through the film to outside during the storage. Fresh weight loss of the mixed sprout vegetables had no difference among the NPB films for seven days storage. The 20,000 cc film had been resulted in that exchange rate of carbon dioxide and oxygen was highest cause of low film permeability than sprouts respiration. But the film is not good for storage because it has been made poor value of off-order even showed high visual quality from panel test after storage. 40,000 cc and 60,000 cc non-perforated breathable films were more suitable for mixed sprout vegetable storage at $10^{\circ}C$. These result suggested that 20,000 cc NPB film was good for single packaged sprout vegetable and 40,000 cc and 60,000 cc non-perforated breathable films were good for mixed packaged sprout vegetable.