• Journal of the Korea Institute of Building Construction
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• v.11 no.4
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• pp.353-362
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• 2011

High Strength Concrete (HSC) has weakness that in a fire, it is spalled and brittles. The phenomenon of spalling is made by water vapor's being confined in watertight concrete. This study is aimed to evaluate explosive spalling properties of high strength concrete with ${\square}100{\times}100{\times}200$ mm specimen and ${\square}400{\times}400{\times}1500$ mm column. To prevent spalling of concrete, fireproof coating and PP fiber are used. As a result, ${\square}400{\times}400{\times}1500$ mm column was prevented spalling likes ${\times}100{\times}100{\times}200$ mm specimen. When concrete protected failure to explosive spalling, quantity heat ratio (which fireproof coating specimen to pp fiber mixed specimen) between ${\square}100{\times}100{\times}200$ mm and ${\square}400{\times}400{\times}1500$ mm was maximum value at 20 minute, but difference of quantity heat ratio decreased and quantity heat ratio of each specimen is almost same at 30 minute.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.517-520
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• 2006

The waterproofing of Building on the roof has been exposed more underground or the other part of waterproofing than environmental factor(solar heat, UV, salt, acid rain, wind, temperature, snow, rain, etc.) or physical factor. So it must be have a waterproofing performance and it has a special technique for the maintaining of concrete durability. Therefore, exposed waterproof layer has to protected from UV, solar heat, rain and the outside environment also, to endurance durability methods spread face plate topcoat material on the waterproof layer. But, actuality faceplate waterproof layer of topcoat materials are unbearable to UV, solar heat and moisture etc. and it doesn't have adhesion with waterproof layer in the middle. So it happens to crack, separating and heaving etc. Therefore, in the study, we will suggest that using of the exposed roof waterproof layer topcoat materials test method manage rooftop waterproof layer for the durability and the stability.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.10
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• pp.1206-1211
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• 2014

This study has been conducted to confirm the effect of sacrificial anode cathodic protection system for 90 days to protect corrosion on pier that is located in Korea. The cathodically protected structure was a slab and a pile cap. Before the construction of cathodic protection system, the macrography was carried out. As a result of the macrography, many corrosion traces were confirmed in this structure. The trace was mainly focused on joint and zones that concrete cover was eliminated. To apply the cathodic protection system, many onsite techniques have been adopted. In addition, to confirm the inner state of steel in concrete properly, a corrosion monitoring sensor (DMS-100, Conclinic Co. Ltd) has been applied. Test factors were corrosion & cathodic protection potential, 4 hour depolarization potential, resistivity and current density. After 90 days from the installation of cathodic protection system, it could confirm that proper corrosion protection effect was obtained by considering the result of tests.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.61-62
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• 2017

In this study, the initiation of steel corrosion was monitored due to chloride attack using embedded sensor. In general, Steel bars embedded in concrete are protected from corrosion by being forming a passive film on the surface. However, the passive film is destroyed by chemical erosion such as concrete carbonation and chloride penetration, and the rebar is exposed to the deteriorating factor and corrosion proceeds. In order to realize the initiation of steel corrosion, OCP and change of Impedance parameter were observed by using Half-cell and EIS method depending on cover depth. As result, 10mm cover showed the impedence increased in 6weeks.

• Journal of the Korean Solar Energy Society
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• v.30 no.3
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• pp.71-80
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• 2010

This study carried out to understand the thermal characteristics of various surface material which compose the city through the observation in the summer. To examine passive cooling effect of planting of building, it is arranged four different materials that is natural grass, grass block, concrete slab and artificial grass. The results of this study are as follows; (1) Natural grass and grass block show the lower surface temperature because of the structures of leaf can do more thermal dissipation effectively. (2) There is little surface temperature between artificial grass and concrete. But there is little high surface temperature difference between natural grass and concrete because of latent heat effect. (3) The concrete can play a role of the tropical nights phenomenon as high heat capacity of concrete compare with other materials. (4) It is nearly same color in artificial grass and natural grass but there is large difference between natural grass and artificial grass at albedo. There is different albedo in near infrared ray range. (5) A short wave radiation gives more effect at the globe temperature than long wave radiation. (6) The artificial turf protected the slab surface temperature increase in spite of thin and low albedo materials.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.83-85
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• 2011

This study investigated the results of insulation heat curing method using double layer bubble sheet in concrete in cold weather environment. First of all, when double bubble sheets are applied, it was shown that concrete was protected from early freezing by remaining between 7℃ and 3℃ even in case outside temperature drops -7℃ below zero until the 3d day from piling. The insulation heat preservation curing method using the double bubble sheet applied in this field prevented early freezing owing to stable curing temperature management, deterring concrete strength development delay at low temperature, and obtained the needed strength. Also, it was proven that the method is highly effective and economic for cold weather concrete quality maintenance through curing cost reduction like construction period shortening and labor cost reduction, etc by reducing the process of temporary equipment installation and disassembling.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.05b
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• pp.25-28
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• 2009

This study investigated the results of insulation heat curing method using double layer bubble sheet in slab concrete in cold weather environment. First of all, when double bubble sheets are applied, it was shown that slab concrete was protected from early freezing by remaining between 5 and $l0^{\circ}C$ even in case outside temperature drops $-11^{\circ}C$ below zero until the 4nd day from piling. The insulation heat preservation curing method using the double bubble sheet applied in this field prevented early freezing owing to stable curing temperature management, deterring concrete strength development delay at low temperature, and obtained the needed strength. Also, it was proven that the method is highly effective and economic for cold weather concrete quality maintenance through curing cost reduction like construction period shortening and labor cost reduction, etc by reducing the process of temporary equipment installation and disassembling.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.30 no.1
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• pp.125-134
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• 2012

This study is determined by tree vigor of analyzing of each object's growth condition in Locational Characteristics and compare the result with impediment extent rate in crown area to provide the management Study about the influence of man-made structures in numbers of protected trees. 68 places where are in the list of Kimpo protected trees were researched in Natural environments, vital degree of trees, number of trees. Crown area was calculated surveying it around the directions of North, East, South and West branching out. Impediment in the area was analyzed after classified into artificial impediment like paved surface(ascon, concrete, block, etc.), a building and a breast wall and natural impediment like soil, stonework and gravel and conclusions are as follow. In analyzing of natural environments, he ground where protected trees have located is consist of 72.05 of manmade structure and artificial in all. There are many protected trees which have less space than crown area for growth suggested by Woo-kyung Sim and Se-kyun Shin in 1992. And it was analyzed that making growth space for protected trees and management of impediment are urgently needed because of that the proportion of impediment covering the crown area has increased as cities are becoming more urbanized results in transforming of trees and weakness of tree vigor. This research shows that under 20% of in crown area is tree vigor determination 1-2 grade 21-50% under is 2-3 grade, higher than 50% is 3-5 grade. More impediment have more difficulty for growing, with the management of root system of protected trees need to be under 20% of rate of land is necessary was improved. As follows are suggested about the standard of management in artificial impediment which influence the number of trees. Firstly, impediment in crown area must be restricted under 20%, but in case outside of the area is not artificial the rate could be higher considerable. Secondly, protected trees growth space secured as much as crown area and impediment must be installed outside the crown area. Thirdly, to move the protected trees, condition of growth space secure must be considered. Fourthly, to develope land, the area around protected trees should be utilized in a park, the area of impediment installation in crown area should be limited as well. Fifthly, As many shown in previous research, for the improvement of old big trees and protected trees, need the tax favor of landowner and purchase of around land, to manage, it needs the budget of local government and advice of expert. Also the study on how various kind of impediment nearby protected trees influence on them has to be continued.

• Structural Engineering and Mechanics
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• v.77 no.5
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• pp.673-689
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• 2021

This paper addresses the efficiency of thermal insulation layers applied to protect structural elements strengthened by fiber-reinforced polymers (FRP) in the case of fire event. The paper presents numerical modeling and nonlinear analysis of reinforced concrete (RC) columns externally strengthened by FRP and protected by thermal insulation layers when subjected to elevated temperature specified by standard fire tests, in order to predict their residual capacity and fire endurance. The adopted numerical approach uses commercial software includes heat transfer, variation of thermal and mechanical properties of concrete, steel reinforcement, FRP and insulation material with elevated temperature. The numerical results show good agreement with published results of full-scale fire tests. A parametric study was conducted to investigate the influence of several variables on the structural response and residual capacity of insulated FRP-confined columns loaded by service loads when exposed to fire. The residual capacity of FRP-confined RC column was affected by concrete grade and insulation material and was shown to improve substantially by increasing the concrete cover and insulation layer thickness. By increasing the VG insulation layer thickness 15, 32, 44, 57 mm, the loss in column capacity after 5 hours of fire was 30%, 13%, 7% and 5%, respectively. The obtained results demonstrate the validity of the presented approach for estimation of fire endurance and residual strength, as an alternative for fire testing, and for design of fire protection layers for FRP-confined RC columns.

• Journal of the Korea Concrete Institute
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• v.20 no.1
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• pp.89-97
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• 2008

By replacing the meta-kaolin with cement and the waste tire chip with fine aggregate separately, the high strength concrete is protected from the spalling in fire and the method to constrain the temperature increase of steel bar within the concrete and the basic properties of the high strength concrete mixed with the material are reviewed. As the result, meta-kaolin increases the self fire proof characteristics of the concrete, the waste tire chip can share the internal expanding pressure so it can be deleted. In detail, using the meta-kaolin about the cement in 4$\sim$8% of weight ratio about the cement and the waste tire chip under the grade scope of 0.6$\sim$3 mm in 5$\sim$10% of weight ratio about the sand is very effective to prevent the spalling.