• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2007.04a
• /
• pp.5-8
• /
• 2007

Selection of proper root barrier as destination part of greening is very important in Root penetration resistance plan. To select proper root barrier, it need to understand composition of greening part, size, kind of plant, connection with waterproofing layer. In this point of view, we have establish greening on the roof or concrete structure, not been understand the structural mechanism. It means that we misunderstood about purpose of greening and using it. So, chosen materials and construction method was not proper for greening, it caused water leakage and decrease performance of concrete structure. Therefore, we examine the practical use of copper sheet considering environmental condition for green roof. Watertightness by water of greening part, root penetration resistance test by root penetration, bacteria resistance by must or bacteria in soil, chemical resistance by rain and chemical agent of fertilizer, and load resistance by soil depth, sire of plant. These suggested test methods could be referred as guideline to test in green roof system because of not exist any performance appraisal guideline or standard. Consequently, it should be analysis as technical and institutional subdividing test methods and it need to study constantly as varied angles.

• Journal of the Korean Geotechnical Society
• /
• v.29 no.10
• /
• pp.49-56
• /
• 2013

The use of geothermal energy has been increased for economic and environmental friendly utilization. Ground thermal conductivity and borehole thermal resistance are very important parameters in the design of geothermal heat pump system. This paper presents an experimental study of heat exchange rate of U and W type ground heat exchangers (GHEs) measured by thermal performance tests (TPTs). U and W type GHEs were installed in a partially saturated dredged soil deposit, and TPTs were conducted to evaluate heat exchange rates under 100-hr continuous operation condition. The heat exchange rates were also calculated by analytical models to estimate borehole thermal resistances and were compared with experimental results. It comes out that multi-pole and equivalent diameter (EQD) models resulted in more accurate agreement than shape factor (SF) model which is currently more often used.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.4C
• /
• pp.265-273
• /
• 2006

This study aims at evaluation of the fire resistance performance of cementitious materials for fire protection of tunnel. For this purpose, the research procedure was divided into three parts. First, base mix proportion with different material type were determined by fire test. Second, the fire test of cementitious materials for fire resistance were performed on base mix proportions to evaluated their performance. Third, the performance of cementitious materials for fire resistance compare to the target value and existing commercial products. If the performance of developed cemetitious materials for fire resistance were satisfied the target value, this studies were stopped. But, this research return to first process if the performance of cementitious materials for fire resistance are not satisfied the target value. As a result of this study, the spalling did not happen for develop and existing commercial product. Also, developed cementitious materials for fire resistance are shown with excellent compressive strength, flexural strength, and bond strength, because it used a height density aggregate. And developed cementitious materials has sufficient resistance for fire.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 1996.06c
• /
• pp.369-378
• /
• 1996

A Lugged steel wheel was operated with two kinds of travel reduction on a sandy clay. " Small -sized transucers of the three-surfaced lug type " were installed to the wheel for the measurement of normal and tangential forces acting on a trailing lug side, lug face and a leading lug side separately . The external results acting on each surface were calculated from those measured forces. This results proved qualitatively that the relationships between external forces and lug surfaces obtained from mathematical analyses were external forces and lug surfaces obtained from mathematical analyses were correct. The traction, the motion resistance and the dynamic load were changing at the three lug surface under various operating conditions . Therefore, total analyses of three surface were indispensable to discuss the performance of the wheel lug.

• Journal of the Korean Wood Science and Technology
• /
• v.43 no.1
• /
• pp.60-67
• /
• 2015

In order to evaluate the bond performance of domestic larch glulam and the glass fiber reinforced plastic (GFRP) rod, the specimen with the GFRP rod bonded-in domestic larch glulam for pull-out test was produced. The test was carried out using various specimens with different gluing depth, width of glue-line and type of adhesive. The cantilever type rahmen structure specimen with bonded-in GFRP rods was produced based on the result of pull-out test, and its moment resistance performance was compared and examined with the moment resistance performance of slotted-in steel plate specimen. As a result of the pull-out test, the most excellent bond performance was found when the insertion depth of GFRP rods was 5 times larger than the diameter of GFRP rods. When the glue-line thickness was 1 mm, the bond performance improved by 17%~29% in comparison to the bond performance in the case of the glue-line thickness of 2 mm. Also, the bonded strength of the specimen used with poly-urethane adhesive was 2.9~4.0 times greater than the bonded strength of specimen used with resorcinol adhesive. The cantilever type rahmen structure specimen with bonded-in GFRP rods showed the moment resistance performance 0.82 times lower in comparison to the slotted-in steel plate specimen used with the drift pin, but the initial stiffness was similar as 0.93 times.

• International Journal of Highway Engineering
• /
• v.20 no.3
• /
• pp.1-9
• /
• 2018

PURPOSES : In order to evaluate a crack resistance at cold joint, sealing tape was adopted to apply at cold joint instead of typical tack coat material(RSC-4). The sealing tape was made by hot sealing material. The crack resistance as function of environmental and traffic loading was measured with visual observation. METHODS : In this study, the crack resistance was evaluated as function of environmental and traffic loading. The freeze-thaw method was adopted for environmental loading of asphalt pavement. condition. The damage of cold joint under freeze-thaw action is initiated by ice expansion load and accelerated by the interfacial damage between new and old asphalt pavement. The traffic loading was applied with wheel tracking machine on the cold joint area of the asphalt pavement for 3 hours at $25^{\circ}C$. The evaluation of crack resistance was measured with visual observation. The freeze-thaw results shows that the sealing tape was significantly increased the crack resistance based on. RESULTS : To estimate the crack resistance at cold joint area due to the environmental loading, the Freeze-thaw test was conducted by exposing the product to freezing temperature(approximately $-18^{\circ}C$) for 24 hours, and then allowing it to thaw at $60^{\circ}C$ for 24 hours. The tack coat material(RSC-4) was debonded after 21 cycles of the Freeze-thaw test. The first crack was observed after 14 freeze-thaw cycle with RSC-4 material. But, the sealing tape was not debonded after 24 cycle test. Also, the sealing tape shows the better performance of the crack resistance under the traffic loading with wheel track test. The crack was generated the under traffic loading with RSC-4(tack coating), however, the crack was not shown with sealing tape. It indicates that the sealing tape has a strong resistance of tensile stress due to traffic loading. CONCLUSIONS :Based on limited laboratory test result, a performance of crack resistance using the sealing tape is better than that of general tack coat material(RSC-4). It means that the sealing tape is possible to extend a pavement service life because the crack, one of the main pavement distresses, will be delayed.

• Journal of Environmental Science International
• /
• v.28 no.5
• /
• pp.503-509
• /
• 2019

To prevent environmental pollution caused by leakage of leachate from waste landfill, vinyl acetate-ethylene (VAE) resin is applied to liner and cover materials to improve their performance. Styrene, styrene butadiene rubber, and VAE are widely used as polymer resins that have excellent water resistance and durability. Further, VAE resin is known to have additional advantages such as adhesion to nonpolar materials and resistance to saponification as a copolymer. In this study, the effect of VAE content on the properties of liner and cover materials was studied. The water and air content ratios, bending and compressive strengths, water absorption ratio, and coefficient of permeability of these materials were measured. The liner and cover materials with 4 wt% VAE showed good properties.

• Journal of the Korea Concrete Institute
• /
• v.20 no.6
• /
• pp.827-832
• /
• 2008

This study evaluated fire resistance performance for hybrid (polypropylene+steel) fiber reinforced high strength concrete column. Full-size columns were constructed and tested with or without fibers using ISO-834 fire curve. As the result of test, Control specimen occurred serious spalling and indicated rapidly internal temperature increasing. Specimen with polypropylene fiber occurred not spalling but steady internal temperature increasing. Specimen with hybrid fiber occurred not spalling as well as does not propagated temperature distribution. Therefore, hybrid fiber reinforced column specimen indicated a good fire resistance performance than other cases.

• Computers and Concrete
• /
• v.26 no.3
• /
• pp.275-283
• /
• 2020

Reinforced concrete (RC) does not provide sufficient resistance against impacts and blast loads, and the brittle structure of RC fails to protect against fractures due to the lack of shock absorption. Investigations on improving its resistance against explosion and impact have been actively conducted on high-performance fiber-reinforced cementitious composites (HPFRCCs), such as fiber-reinforced concrete and ultra-high-performance concrete. For these HPFRCCs, however, tensile strength and toughness are still significantly lower compared to compressive strength due to their limited fiber volume fraction. Therefore, in this study, the tensile behavior of slurry-infiltrated fiber-reinforced cementitious composites (SIFRCCs), which can accommodate a large number of steel fibers, was analyzed under static and dynamic loading to improve the shortcomings of RC and to enhance its explosion and impact resistance. The fiber volume fractions of SIFRCCs were set to 4%, 5%, and 6%, and three strain rate levels (maximum strain rate: 250 s^-1) were applied. As a result, the tensile strength exceeded 15 MPa under static load, and the dynamic tensile strength reached a maximum of 40 MPa. In addition, tensile characteristics, such as tensile strength, deformation capacity, and energy absorption capacity, were improved as the fiber volume fraction and strain rate increased.

• Fisheries and Aquatic Sciences
• /
• v.20 no.7
• /
• pp.15.1-15.7
• /
• 2017

An 8-week feeding trial was conducted to study the effect of dietary supplementation of a biofloc powder on growth performance and non-specific immune response of Litopenaeus vannamei. Seven experimental diets were prepared with supplementation of graded levels of dried biofloc powder by 0, 0.5, 1.0, 2.0, 4.0, 6.0, and 8.0% (designated as Con, BF0.5, BF1, BF2, BF4, BF6, and BF8, respectively). Triplicate groups of shrimp ($1.01{\pm}0.01g$) were hand-fed with one of the diets four times a day. At the end of the feeding trial, significantly (P<0.05) higher growth performance and feed utilization were obtained in BF4 groups compared to those fed the Con diet. The innate immunity of shrimp was improved by the dietary supplementation of biofloc. Dietary inclusion of biofloc at the level of 4.0% significantly increased disease resistance of shrimp against Vibrio harveyi. The results indicate that biofloc might be used as a dietary supplement for growth performance, innate immunity and disease resistance of Pacific white shrimp.