• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.527-528
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• 2009

Effects of temperature on fatigue resistance of crack zone in concrete members repaired by injecting epoxy resin was experimentally studied. First, a fatigue machine that produces small movement similar to those observed in actual cracks was developed. It was made clear that the rise of temperature changes a mode of fracture at the repaired zone and sharply dropped fatigue resistance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.138-144
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• 2013

This study is for quality standard establishment of urethane waterproofing membrane method which is mostly applied to waterproofing method for underground parking lot and rooftop. The experiments were carried out on color differences, membrane thickness, tensile property by curing period of liquid urethane before placing protective concrete, and resistance of crack movement according to different substrate surface and reinforcement of non-woven fabric. As a result of experiments, it was found that color differences is increase, membrane thickness is thick, tensile property is low as concrete placing period is shorter. In the fatigue property, membrane thickness of 3 mm was not broken, but 1~2 mm was broken and in the case of the membrane reinforced with non-woven fabric was more stable comparatively non-reinforcement one.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.201-202
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• 2022

In this study, the high performance silicone was developed to assure the inter-layer joint in apartment house. The tensile strength, the elongation, the bond strength and the fatigue tests were conducted. As a result, it was confirmed that the performance of high -performance silicone was superior to the existing elastic paint. Therefore, it is expected that it will help to secure the quality of inter-layer joints in apartment houses.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.535-538
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• 2005

The problem of the crack which occures from the reinforced concrete structure. could be caused by the complexed factors. When the crack happen, it caused fatal blemish to manage and maintain the structure such as structural problem, licking, spalling, viewing Even though they study and work hard to solve this kind of problem in the world, there are no countermeasure for perfect prevention of crack. After the crack checked out, a method of repair-reinforcement has been sutdied and operated actively. In this experiment, studied durability of repair material. Experiment wave and durability of epoxy and urethane's were shown good result, and micro cement's durability displayed result that is not good. Result of a repeat tired experiment displayed result that micro cement is bad.

• Journal of the Society of Disaster Information
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• v.12 no.4
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• pp.373-380
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• 2016

In order to develop composite fiber panels that can maximize the protection and blast resistance of the existing structures by improving lightweight, high-strength and fireproof performances of the single layer material of precast panels, the basic properties of the inner and outer covers that are mixed with aramid fibers (AF) and polyester fibers (PF) were evaluated in this study. Also, a basic study was performed on the performance of composite fiber panels by testing Nano-sized composite materials that are lightweight and excellent in fire resistance for their compressive strength, bending strength and tensile strength.

• Tuberculosis and Respiratory Diseases
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• v.49 no.6
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• pp.691-702
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• 2000

Background : Acute lung injury (ALI) is a commonly encountered respiratory disease and its prognosis is poor when the treatment is not provided promptly and properly. However no specific pharmacologic treatment is currently available for ALI, although recently several supportive drugs have been under scrutiny. We studied anti-inflammatory effects of pentoxifylline (PF), a methylated xanthine, and ONO-5046, a synthetic neutrophil elastase inhibitor on lipopolysaccharide (LPS)-induced ALI in vitro. Methods : To establish an in vitro model of LPS-induced ALI, primary rat alveolar macrophages and peripheral neutrophils in various ratios (1:0, 5:1, 1:1, 1:5, 0:1) were co-cultured with transformed rat alveolar epithelial cells (L2 cell line) or vascular endothelial cells (IP2-E4 cell line) under LPS stimulation. Each experiment was divided into five groups-control, LPS, LPS+PF, LPS+ONO, and LPS+PF+ONO. We compared LPS-induced superoxide anion productions from primary rat alveolar macrophages and peripheral neutrophils in various ratios, and the resultant cytotoxicity on L2 cells or IP2-E4 cells between groups. In addition we also compared the productions of tumor necrosis factor (TNF)-$\alpha$ interleukin (IL)-$1{\beta}$, monocyte chemotactic protein(MCP)-1, IL-6, and IL-10 as well as mRNA expressions of TNF-$\alpha$ inducible nitric oxide synthetase(iNOS), and MCP-1 from LPS-stimulated primary rat alveolar macrophages between groups. Results : (1) PF and ONO-5046 in each or both showed a trend to suppress LPS-induced superoxide anion productions from primary rat alveolar macrophages and peripheral neutrophils regardless of their ratio, except for the LPS+PF+ONO group with the 1:5 ratio, although statistical significance was limited to a few selected experimental conditions. (2) PF and ONO-5046 in each or both showed a trend to prevent IP2-E4 cells from LPS-induced cytotoxicity by primary rat alveolar macrophages and peripheral neutrophils regardless their ratio, although statistical significance was limited to a few selected experimental conditions. the effects of PF and/or ONO-5046 on LPS-induced L2 cell cytotoxicity varied according to experimental conditions. (3) PF showed a trend to inhibit LPS-induced productions of INF-$\alpha$ MCP-1, and IL-10 from primary rat alveolar macrophages. ONO-5046 alone didnot affect the LPS-induced productions of proinflammatory cytokines from primary rat alveolar macrophages but the combination of PF and ONO-5046 showed a trend to suppress LPS-induced productions of INF-$\alpha$ and IL-10 PF and ONO-5046 in each or both showed a trend to increase LPS-induced IL-$\beta$ and IL-6 productions from primary rat alveolar macrophages. (4) PF and ONO-5046 in each or both showed a trend to attenuate LPS-induced mRNA expressions of TNF-$\alpha$ and MCP-1 from primary rat alveolar macrophages but at the same time showed a trend increase iNOS mRNA expression. Conclusion : These results suggest that PF and ONO-5046 may play a role in attenuating inflammation in LPS-induced ALI and that further study is needed to use these drugs as a new supportive therapeutic strategy for ALI.