• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.4
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• pp.1-8
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• 2012

The aim of this study is to evaluate fire-induced damage for shield tunnel linings. Full-scale fire test was conducted to evaluate fire-induced damage. Residual compressive strength was measured on the core samples of shield tunnel lining subjected to high temperatures. Heating temperature was predicted by XRD and TG analysis. As a result, Strength degradation of concrete with temperatures can be evaluated by residual compressive strength of core samples. In addition, residual compressive strength can be estimated by previous studies if heating temperature is exactly predicted. It is possible that heating temperature is predicted by XRD and TG analysis at $450^{\circ}C$. For more accurate prediction of heating temperature it should be performed both instrumental analysis and analytical methods with temperatures ranging from $400{\sim}600^{\circ}C$.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.2
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• pp.1-5
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• 2008

The object of this experimental and simulation study is to find out heated temperature and range from the Oxy-acetylene cutting point of reinforcing bars (D10, D13, D16, D19, D22, D25 for each cases of SD3O and SD40) in room temperature ($20{\sim}22^{\circ}C$). This cutting is under the condition that a skilled worker cut one bar per a time. The results are these. 1. The temperature of the point 1 of reinforcing bars cut with Oxy-acetylene cutter is over 700$^{\circ}C$ under 1000$^{\circ}C$, but the temperature of the point 2 of reinforcing bars cut with Oxy-acetylene cutter is under 200$^{\circ}C$ 2. The temperature of the point that is apart 2cm from Oxy-acetylene cutting point is not over 200$^{\circ}C$, so reinforcing bars has not transform to be brittle. The results of simulation for temperatures of the each point apart from Oxy-acetylene cutting point is similar to upper experimental results.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.509-512
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• 2008

The nitrogen adsorption method was used to evaluate the change fine pore structure of concrete under high temperature. The mechanical properties and chloride ion diffusion coefficient were also measured. Two dimension FEM model for the life expectancy of RC structure was built considering the effect of high temperature. The porosity under 0.01${\mu}m$ decreased in proportion to the temperature. However, that of $0.01{\mu}m{\sim}0.1{\mu}m$ increased. The strength decreased and the chloride ion diffusion coefficient increased in the temperature range of $200{\sim}600^{\circ}C$.

• Solar Energy
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• v.12 no.1
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• pp.88-94
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• 1992

A small-scale solar collector and tracking system, using a Fresnel lens of $0.5m^2$, and novel compact fluidized-bed solar receiver[FBR] of closed type has been developed for high temperature solar gas heating. The FBR was improved in carrying over of SiC powder and thermo-siphon effect. The maximum outlet air temperature of 1140K and the maximum thermal efficiency of 64% were obtained. The present FBR's operated efficiently at extremely high temperatures in comparison with conventional solar receivers, composed of flat or tubular solid surfaces.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.292.1-292.1
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• 2013

ZnO, Ga2O3, In2O3 등 산화물 반도체는 최근 디스플레이, 태양전지 등 전자산업에서 중요한 소재로 전 세계적으로 많이 연구되고 있다. 그 중에서도 ZnO는 나노와이어, 나노점 등 나노구조체 형태로 제조가 가능해 짐에 따라 센서 등의 반도체 소자로의 응용가능성이 매우 큰 것으로 알려져 있다. ZnO 나노와이어는 chemical vapor deposition법을 이용하여 $800^{\circ}C$이상의 고온에서 제조 가능하다고 알려져 있다. 또한 저온 증착법으로 수열합성법이 있는데, 이때에는 사용되는 화학물질, 성장온도 등 제조 조건에 따라 특성이 크게 달라진다. 본 연구에서는 수열합성법으로 제조한 ZnO 나노와이어의 성장온도에 따른 물성을 분석하였다. 특히 ZnO 나노와이어의 지름 및 길이 변화가 두드러지게 나타났다. 성장온도 변화에 따라 나노와이어의 지름이 30 nm부터 100 nm까지 변화하였으며, 이에 따른 광학적 특성 또한 변하였다. XRD, SEM, PL, Raman 분광법으로 측정한 결과를 발표할 예정이다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.89-90
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• 2022

In this study, the correlation between the compressive strength and the B3B bending strength of the high-temperature hydrothermal concrete according to the presence or absence of aggregate incorporation was examined. As a result of the experiment, as the heating temperature increases, the strength decreases and shows a high correlation.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.239-240
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• 2021

In this study, we conducted a study to evaluate the more accurate mechanical properties of concrete damaged by fire. In relation to this, in this study, the results of compressive strength and biaxial flexural strength were compared for concrete that received high temperature heat. As a result, both the compressive strength and the biaxial bending strength decreased as the heating temperature increased. As a result of examining the correlation between the compressive strength and the biaxial flexural strength, the biaxial flexural strength was smaller than the compressive strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.133-134
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• 2021

In this study, the effects of aggregates on the properties of concrete as a study to determine the mechanical properties of high-temperature damaged concrete were examined. The samples to be reviewed are cement paste, mortar, and concrete, and the strength characteristics were reviewed after heating the compression strength and tensile strength properties. The increase in magnetic shrinkage at around 100℃ showed a significant drop in strength in mortar, which does not contain aggregates or has a small diameter, and after 300℃, concrete showed a sharp drop in strength due to the hydration and aggregation of cement.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.127-128
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• 2021

In this study, a study was conducted to analyze thermal diffusion according to the depth of concrete exposed to high temperatures. For thermal diffusion analysis, a test specimen in which K-type sheath thermocouples were poured in 0, 10, 20, 30, and 40 mm sections was manufactured, and thermal diffusion measurement was performed through one-sided heating for 180 minutes under heating conditions. As a result of the review, it was shown that as the temperature condition increased, the heat diffusion increased as the depth increased.

• Korea Journal of Geothermal Energy
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• v.4 no.3
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• pp.5-10
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• 2008