• Corrosion Science and Technology
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• v.8 no.4
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• pp.157-161
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• 2009

The corrosion resistance of reinforcing bar was studied to endure the marine environment during shipment. The red rust on the surface did not damage the adherence in the concrete structures, especially in highly alkaline environment, but made the consumer doubt of the quality. The passivation process by alkalization of the quenching water in the tempcore process failed to endure the long shipping period. The ceramic coating by sol-gel process improved the corrosion resistance without damaging the mechanical properties and adherence between concrete and reinfiorcing bar. Optimal concentration of the coating solution and coating temperature were tested. No additional energy was necessary for the coating process by spraying during cooling process, resulting simplified process and low cost. Salt spray test, cyclic corrosion test and atmospheric test were employed to confirm the resistance. The corrosion rates were presented by rating number and polarization resistance. The coating layer was examined by FIB, XRD and SEM etc.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.75-76
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• 2015

This study has examined the impact resistance and blast resistance characteristics of HPFRCC as a research on impact resistance and blast resistance characteristics using high volume mortar and high velocity projectile for evaluating the protection performance of actual buildings as small quantity experiment of laboratory conditions is performed although there was an instance of performing research on mortar that has reinforced fiber followed by the rise of problems on the damage of human life and buildings created due to explosion and shock. As a result, the destruction loss area and depth have decreased in case of the surface compared to the rear side. As tensile strength and tenacity have increased with the increased fiber replacing ratio, a tendency of destruction loss area and depth getting decreased was shown as the impact resistance has increased.

• Journal of the Korean Institute of Gas
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• v.26 no.1
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• pp.34-40
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• 2022

Gas cylinder cabinets have risks such as cylinder explosion and scattering of debris when a fire occurs. These risks are likely to cause gas spills and cause secondary damage. In order to reduce damage, it is very important to secure the fire resistance performance of the gas cylinder cabinet. In foreign countries, NFPA codes in the United States and EN-14470-2 in Europe stipulate fire resistance test standards for gas cylinder cabinets to protect internal cylinders for a certain period of time in a situation where gas cylinder cabinets are exposed to flames. However, in Korea, only internal pressure performance and airtight performance standards are specified, and the target is limited to piping, and research and regulations for the fire resistance performance of gas cylinder cabinets are insufficient compared to overseas. Therefore, in this study, finite element analysis was used to establish fire resistance standards for domestic gas cylinder cabinets. In the event of a fire, optimal conditions are derived in terms of structure and material.

• Journal of the Society of Disaster Information
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• v.19 no.2
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• pp.262-269
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• 2023

Purpose: In this study,fire-resistance test were executed to evaluate the effectiveness of the fireproof panel attached to the PSC slab in tunnel. Method: For the fire resistance test, the RWS curve was applied and the furnace of the KICT was used. Result: As a result of the experiment, the maximum temperature measured on the concrete surface of the PSC slab with the fireproof panel was 321.8℃, which was lower than the damage limit temperature of 380℃ for concrete. Also, at the t=25mm, the maximum temperature was 35.2℃, which was lower than the damage temperature of steel, 250℃. The use of precast fire resistance panel(t=30mm) improves fire resistance of PSC structures. Conclusion: As a result of the test, a reinforcement method for attached a fireproof panel in case of fire in a tunnel or an underground roadway is provided to protect a structure from fire. In the future, it is necessary to perform the static performance test of the slab to which the fireproof panel is attached, and to confirm the adhesion performance of the fireproof panel by performing the pull-off test and the fatigue test.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.69-73
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• 2001

Damage induced by low-velocity impact on the curved composite laminates was experimentally evaluated for CFRP cylindrical shells with the radius of curvatures of 50, 150, 300, and 500 mm. The result was then compared with that of flat laminates. The radius of curvatures and the effective shell stiffness appeared to considerably affect the dynamic impact response of curved shells. Under the same impact energy level, the maximum contact force increased with the decreasing radius of curvatures, with reaching 1.5 times that for plates at the radius of curvature of 50 mm. Since the maximum contact force is directly related to the impact damage, curved laminates can be more susceptible to delamination and less resistant to the low-velocity impact damage. The distribution of delamination along the thickness direction of curved laminates are also different from that of flat plates. Delamination was distributed rather even]y at each interface along the thickness direction of curved laminates. This implies that the effect of curvatures has to be considered for the design of a curved composite laminate.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.71-75
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• 2005

For the damage tolerance improvement of conventional laminated composites, stitching process have been utilized for providing through-thickness reinforcements. 2D preforms were stacked with S-2 glass plain weave and S-2 glass MWK (Multi-axial Warp Knit) L type. 3D preforms were fabricated using the stitching process. All composite samples were fabricated by RTM (Resin Transfer Molding) process. To examine the damage resistance performance the low speed drop weight impact test has been carried out. For the assessment of damage after the impact loading, specimens were examined by scanning image. CAI (Compressive After Impact) tests were also conducted to evaluate residual compressive strength. Compared with 2D composites, the damage area of 3D composites was reduced by 20-30% and the CAI strength showed 5-10% improvement.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.264-267
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• 2005

Impact damages are very important in the perspective of residual strength of composite structures such as aircrafts, ships, and trains because those damages are sometimes not visible on the surface of the point of impact and the impact resistance of laminated composites is usually not so high. Thus, the impact characteristics of laminated composites should he investigated for the safety of composite structures. This paper investigates the low-velocity impact and damage detection conducted on woven carbon/epoxy laminates. Experimental results show that the type of damage is dependent on the impact energy level and the delamination area becomes larger as the impact energy increases.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1990.04a
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• pp.37-43
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• 1990

This paper develops practical models and methods for the assessment of safety and rating of damaged and/or deteriorated bridges by incorporating a system identification technique for the explicit inclusion of the degree of deterioration or damage and of the actual bridge response. And, based on the proposed model, reliability-based rating methods are proposed as LRFR(Load and Resistance Factor Rating) and system reliability-index rating criteria. The proposed limit state model explicitly accounts for the degree of deterioration or damage in terms of the damage and response factors. The damage factor in the paper is proposed as the ratio of the current stiffness to the intact stiffness. Based on the observation and the results of applications to existing bridges, it may be concluded that the proposed rating models, which explicitly account for the uncertainties and the effects of degree of deterioration or damage based on the system identification technique, provide more realistic and consistent safety-assessment and capacity-rating.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.86-91
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• 2002

Glass/phenolic composite laminates have been used in the field of non-flammable light rail transit and their applications have expanded more widely. Low velocity impact tests have been used to evalute the effect of temperature and acceleration aging on low velocity impact response of phenolic matrix composites reinforced with woven E-glass fabric. The damage of matrix cracking and delamination are suddenly reduced the compressive strength after impact. The damage area increases with increasing temperature and impact energy. UT C-scan is used to determine damage areas by impact loading. Therefore, all this observations indicate reduced impact damage resistance and damage tolerance of the laminates at elevated temperature.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.295-300
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• 2002

To establish an optimum condition in the surface treatment and curing process will be an important parameters for the fabrication of multilayered hybrid composite materials, A17075/CFRP (CARALL : carbon fiber reinforce aluminum laminates). Effects of carbon fiber direction and thickness variation in tensile strength were investigated. And impact damage behavior of carbon fiber reinforce plastic (CFRP) and CARALL were investigated also, it was found that a partial stress increase in order of epoxy adhesive, A17075, CFRP. And the partial stress of CFRP carried out a great portion of applied stress. The impact damage resistance of CARALL was higher than that of CFRP. This is because both side Al sheet of CARALL absorb a great of impact damage.