• Korean Journal of Construction Engineering and Management
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• v.10 no.5
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• pp.123-134
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• 2009

Since 1970s, urethane waterproofing method is broadly used in rooftops, underground spaces, and sports stadium for its outstanding ultraviolet blockage, watertightness, and elasticity. However, development of slippage-resistance and endurance, improvement of function considering convenience and visually pleasing of users, urethane waterproofing method is necessary, since rooftops and underground spaces have slippage and external force risks. Therefore, many improved waterproofing methods are being developed and, recently, embo-thane waterproofing method, which applies embo-spray coating system, has been developed. This paper explains exposure, nonexposure, and floor-material of embo-thane waterproofing method, and then perform experimental study for comparison with urethane waterproofing method about tensile strength, coefficient of expansion, performance of bond, anti-abrasion, and slippage-resistance. In addition, the performance index was presented for the superiority of embo-thane waterproofing method compared to urethane by setting up evaluation criteria considering not only physical performance but also design side of embo-thane waterproofing method, and Value Analysis applying AHP. Also for an assessment considering uncertain result, Monte Carlo Simulation Method was used to operate reliability analysis through statistic approach method.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.597-600
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• 2008

In this study the reason which researches the feature of the exposure type waterproofing it uses the technique of the soft FRP it uses the soft unsaturated polyester and the square groove cutting technique with respects and solves the interface separate problem because of the rigid FRP it is used with the repairs and retrofit materials it is caused by in adhesion of concrete insufficiency. The feature of this technique was the dispersion and the reinforcement of the fatigue stress due to the integration behavior and the reinforcement due to the glass-fibre of the concrete due to the soft FRP resin and, it investigated the crack appearance confrontation of concrete and the cohesion stability of the concrete due to the square groove cutting technique with importance. The result of research when it applies the soft FRP with the exposure type waterproofing, is judged with the fact that it will be able to expect a bulge resistance confrontation and creak confrontation ability and cohesion stability improvement.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.553-561
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• 2020

Water-soluble rubber asphalt-based waterproofing material, which is one of the waterproofing materials for building structures, is mainly used indoors (toilet, kitchen, balcony, etc.). In general, asphalt-based materials are used for non-exposed installation, rather than as exposed type as they do not deviate from their usual basic black pigmentation, and water-soluble rubber asphalt-based coating waterproofing materials are basically limited to indoors because of their low physical properties. Accordingly, in order to improve the tensile and elongation properties, a silane coupling agent, an inorganic filler, and a processor oil w ere added to improve the physical properties, and accordingly, the basic physical properties of the outdoor coating waterproofing material quality standard were analyzed. As a result, the water-soluble rubber asphalt coating waterproofing material compared with the exposure quality standard showed a result that exceeded the basic physical property quality standard of silicone rubber in all items under test evaluation, but the tensile strength and tear strength of the first class of urethane rubber were chloroprene. It was found that the performance compared to the quality standards of rubber-based tear strength was about 34.2% to about 40.8%.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.339-340
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• 2018

Contemporary concrete structures make use of underground spaces as parking lots and other comfort facilities for efficiency purposes. As underground environmental conditions are in constant exposure to degradation factors from the environment such as groundwater, hydraulic and soil pressure, structural movement and settlement, structural defects in the form of leakage occur. Current maintenance regulations and regimes are unable to respond to this field, as degradation mechanisms in underground environments are still unclear. In this regard, this study proposes the utilization of integrated information sharing system that can provide various technical information for construction designs to prevent leakages in underground concrete structures.

• Safety and Health at Work
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• v.7 no.1
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• pp.63-71
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• 2016

Background: Construction painters have not been studied well in terms of their hazards exposure. The objective of this study was to evaluate the exposure levels of total volatile organic compounds (TVOCs) for painters in the construction industry. Methods: Activity-specific personal air samplings were carried out in three waterproofing activities [polyurethane (PU), asphalt, and cement mortar] and three painting activities (epoxy, oil based, and water based) by using organic-vapor-monitor passive-sampling devices. Gas chromatograph with flame ionization detector could be used for identifying and quantifying individual organic chemicals. The levels of TVOCs, by summing up 15 targeted substances, were expressed in exposure-index (EI) values. Results: As arithmetic means in the order of concentration levels, the EIs of TVOCs in waterproofing works were 10.77, 2.42, 1.78, 1.68, 0.47, 0.07, and none detected (ND) for indoor PU-primer task, outdoor PU-primer task, outdoor PU-resin task, indoor PU-resin task, asphalt-primer task, asphalt-adhesive task, and cement-mortar task, respectively. The highest EI for painting works was 5.61 for indoor epoxyprimer task, followed by indoor epoxy-resin task (2.03), outdoor oil-based-spray-paint task (1.65), outdoor water-based-paint task (0.66), and indoor oil-based-paint task (0.15). Assuming that the operations were carried out continuously for 8 hours without breaks and by using the arithmetic means of EIs for each of the 12 tasks in this study, 58.3% (7 out of 12) exceeded the exposure limit of 100% (EI > 1.0), while 8.3% (1 out of 12) was in 50e100% of exposure limit (0.5 > EI > 1.0), and 4 tasks out of 12 were located in less than 50% of the limit range (EI < 0.5). Conclusion: From this study, we recognized that construction painters are exposed to various solvents, including carcinogens and reproductive toxins, and the levels of TVOC concentration in many of the painting tasks exceeded the exposure limits. Construction workers need to be protected from chemical agents during their painting works by using personal protective devices and/or work practice measures. Additional studies should focus on the exposure assessment of other hazards for construction workers, in order to identify high-risk tasks and to improve hazardous work environments.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.33 no.2
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• pp.115-125
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• 2023

Objectives: This study was conducted to measure the level of radon in the air at a highway tunnel construction site in a gneiss area using the New Austrian Tunneling Method (NATM) and to evaluate exposure levels by occupation. Methods: Radon concentrations in the air were measured using E-PERM at points 300 m, 600 m, and 900 m from the tunnel entrance during the excavation and waterproofing work inside the tunnel. In addition, radon concentrations were measured during external excavation to compare with the inside of the tunnel. Personal exposure levels for major occupations including tunnel workers, construction equipment operators, waterproofers, shotcrete workers, and safety and health managers who participated in the construction were estimated using radon concentration measured in the work process area and working hours by occupation. Results: As a result of a total of 77 radon measurements, the geometric mean (GM) concentration was 71.1 Bq/m³, and the maximum concentration was 127.3 Bq/m³, which was below the indoor air quality criteria. Radon concentration by process decreased in the order of the tunnel excavation process (GM= Bq/m³, GSD=1.2), waterproofing process (GM=73.35 Bq/m³, GSD=1.2), and outside excavating process (GM=45.28 Bq/m³, GSD=1.2). Processes inside the tunnel were significantly higher than outside excavating processes (p<0.05). There was no statistically significant difference in radon concentration measured inside by distance from the tunnel entrance, but the innermost point of the tunnel, 900 m (GM=79.24 Bq/m³, GSD=1.27), measured the highest. Conclusions: The occupation with the highest individual exposure to radon was tunnel worker (64.16 Bq/m³), followed by construction equipment driver (64.04 Bq/m³) and waterproofer (63.13 Bq/m³).

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.11a
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• pp.126-127
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• 2017

This study investigates the effect of improving the heat resistance performance when carbon fiber is mixed in the polyurea coating material. A tensile strength test method was carried out with the carbon fiber mixed polyurea specimens at an interval of 7, 14, and 21 days after heat treatment at 140±2℃. The test results showed that there was a significant decrease in the tensile strength performance. While the elongation and tensile performance decreased greatly, it was confirmed nevertheless the overall performance was maintained. This study proposes that mixing carbon fiber to the polyurea resin can effectively secure long-term heat resistance, thereby solving the problem of deterioration of physical properties caused by exposure to ultraviolet rays.

• Journal of the Korea Institute of Building Construction
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• v.18 no.5
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• pp.455-461
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• 2018

The purpose of this study is to evaluate the tensile strength performance of the polyurethane coating material used as the waterproofing material in concrete structures. A linear regression equation is proposed to establish a correlation on the tensile strength of polyurethane coating membrane against periodic exposure to chemical degradation. The polyurethane film membrane showed a minimum strength of 23% to a maximum of 38% when subjected to chemical degradation. The elongation rate showed a relation with the tensile strength deterioration rate of at least 15% to 22% at maximum, and the proposed regression equation could be used to predict the degree of performance change of the polyurethane coating membrane under chemical degradation condition.

• Journal of Sensor Science and Technology
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• v.28 no.6
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• pp.377-384
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• 2019

People currently spend more than 80% of their time indoors; therefore, the management of indoor air quality has become an important issue. The contamination of indoor air can cause sick house syndrome and various environmental diseases such as atopy and nephropathy. Formaldehyde gas, which is the main contaminant of indoor air, is lethal even with microscopic exposure; however, it is commonly used as an adhesive and waterproofing agent for indoor building materials. Therefore, there is a need for a gas sensor capable of detecting trace amounts of formaldehyde gas. In this review, we summarize recent studies on metal oxide-based semiconductor gas sensors for formaldehyde gas detection, methods to improve the gas-sensing properties of metal oxides of various dimensions, and the effects of catalysts for the detection of parts-per-billion level gases. Through this, we discuss the necessary characteristics of the metal oxidebased semiconductors for gas sensors for the development of next-generation sensors.

• KIEAE Journal
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• v.13 no.5
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• pp.89-96
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• 2013

Green roofs can reduce surface water runoff, provide a habitat for wildlife moderate the urban heat island effect, improve building insulation and energy efficiency, improve the air quality, create aesthetic and amenity value, and preserve the roof's waterproofing. Green roofs are mainly divided into three types : intensive, simple-intensive, and extensive. Especially, extensive roof environment is a harsh one for plant growth; limited water availability, wide temperature fluctuations, high exposure to wind and solar radiation create highly stressed environment. This study, aimed at extensive green roof, was carried out on the rooftop of the library at Seoul Women's Univ. from October to November, 2012 and from March to August, 2013. To suggest the most effective vegetation model for biodiversity and heat island mitigation, surface temperatures were monitored by each vegetation model. We found that herbaceous plants of Aster sphathulifolius, Aceriphyllum rossii and Belamcanda chinensis, shrub of Syringa patula 'Miss Kim', Thymus quinquecostatus var. japonica, Sedum species can mixing each other. Among them, the vegetation models including Sedum takesimense, Aster sphathulifolius, Thymus quinquecostatus var. japonica was more effective on the surface temperature mitigation, because the species have the tolerance and high ratio of covering, and also in water. Especially, in the treatment of bark mulching, they helped to increase the temperature of vegetation models. In the case of summer, temperature mitigation of vegetation models were no significant difference among vegetation types. Compared to surface temperature of June, July and August were apparent impact of temperature mitigation, it shows that temperature mitigation are strongly influenced by substrate water content.