This study develops numerical model of mega composite columns in fire and investigates the residual areas below 500℃ after 3 hours. In order to perform heat transfer analysis, thermal properties of steels and concrete were adopted from Eurocodes. In addition to, the temperature distributions of composite columns with respect to fire tests were compared with numerical analysis results. As a result, the residual areas below 500℃ of mega composite columns were evaluated.

The present study is intended to comparatively investigate the changes in microstructure and tensile properties at room and elevated temperatures in commercial AM50(Mg-5%Al-0.3%Mn) and 0.3 wt%CaO added ECO-AM50 alloys produced by permanent mould casting. The typical microstructure of AM50 alloy was distinctively characterized using two intermetallic compounds, β(Mg17Al12) and Al8Mn5, along with α-(Mg) matrix in an as-cast state. The addition of a small amount of CaO played a role in reducing dendrite cell size and quantity of the β phase in the AM50 alloy. It is interesting to note that the added CaO introduced a small amount of Al2Ca adjacent to the β compounds, and that inhomogeneous enrichment of elemental Ca was observed within the β phase. The ECO-AM50 alloy showed higher hardness and better YS and UTS at room temperature than did the AM50 alloy, which characteristics can be mainly ascribed to the finer-grained microstructure that originated from the CaO addition. At 175˚C, higher levels of YS and UTS and higher elongation were obtained for the ECO-AM50 alloy, demonstrating that even 0.3 wt%CaO addition can be beneficial in promoting the heat resistance of the AM50 alloy. The combinational contributions of enhanced thermal stability of the Ca-containing β phase and the introduction of a stable Al2Ca phase with high melting point are thought to be responsible for the improvement of the high temperature tensile properties in the ECO-AM50 alloy.

본 연구는 온도 증가에 따른 압축을 받는 H형 강재의 플랜지와 웨브의 국부 및 전체좌굴응력 내화해석 프로그램 개발과 플랜지와 웨브가 항복파괴전에 국부좌굴이 일어나지 않을 한계 판폭두께비의 상관값을 구하는 프로그램을 개발하는 것이다. 고온에서의 강재의 응력-변형도 관계식은 EC3:Part 1.2를 근거로 하였으며, 비교, 검토를 위하여 영국 BS5950의 강재를 대상으로 온도 증가에 따른 압축을 받는 강재의 플랜지와 웨브의 파괴온도와 하중을 본 연구의 내화해석 프로그램으로 예측하였다. 본 연구는 좌굴 및 항복에 대한 내화해석 프로그램을 개발하는 것을 목적으로 하고 적용 예를 통하여 좌굴 및 한계 판폭두께비를 분석하고 개발 프로그램의 타당성을 검토하였다.

According to the IPCC report (IPCC, 2001), the global-mean surface temperature has risen by 0.6 oC during the 20th century due to the increase of atmospheric concentrations of greenhouse gases, and the mean temperature of the Korean Peninsula is also risen by 1.5 oC during the same period due to global warming as well as rapid urbanization. During the 21st century, the global-mean temperature is projected to rise 1.5-5.8oC associated with the various scenarios from IPCC Special Report on Emission Scenario (SRES) (2000). Climate change is expected to have important impacts on the relationship between crops and insect pests as well as on human societies. Frazier et al. (2006) demonstrated that warm-adapted insect species have much higher maximum population growth rate (intrinsic rate of increase) than do cold-adapted species; which indicates biochemical and physiological adaptations of insects do not overcome the constrain of thermodynamics. Consequently, global warming could lead to an increase in the number of insects worldwide. This presentation will discuss the changes in the population abundance of several citrus pests according to global warming. The differences of population growth rates between normal year's or past temperatures and elevated temperatures were compared, and also analytical models such as matrix model and predator-prey model were applied to project the performance of population dynamics of some pests and natural enemy.

본 논문은 화재시 온도상승에 따른 H-형강 기둥의 내력에 관한 연구이다. 주요 매개변수는 온도, 세장비와 하중비이다. 온도 상승시 강재의 물리적 특성은 EC3 Part1.2에 따랐다. 온도상승에 따른 국부좌굴의 임계온도는 재료의 항복강도와 판폭두께비가 클수록 더 낮아진다. 균등한 열을 받는 철골 기둥의 내혁 평가는 LRFD에 따른 축력과 강축 및 약축 모멘트에 대하여 고려하였다.

In this study, we study the characteristics of thermal diffusion of cement paste at elevated temperature. Results of the experiments can be used to predict the fire damaged temperatures of concrete, and to recommend proper methods for repair and rehabilitation.

In this study, we study the characteristics of thermal diffusion of cement paste at elevated temperature. Results of the experiments can be used to predict the fire damaged temperatures of concrete, and to recommend proper methods for repair and rehabilitation.

Geopolymer has recently emerged as an environmentally sustainable material considered to be an alternative to conventional Portland cement. Current study exhibits and discusses the results of experiment on the alteration in mechanical strength of fly ash-based geopolymer mortar activated by alkaline solution with three different sodium hydroxide solution concentrations (etc 10M, 14M and 18M) after exposure to elevated temperatures ranging from 100oC to 1000oC. Thegeopolymermotarexhibitedits strength increase after exposure at 100oC or 200oC ,followed bythe considerable strength loss in strength between 300oC and 700oC. However, the mortar strength rose slightly after exposure to temperature range from 800oC to 1000oC due to the viscous sintering process.

In this study, a reduction in inter-laminar shear strength of FRP reinforcing bars, which is domestically produced, subjected to high temperatures was investigated. The inter-laminar shear tests were conducted on the rebar specimens conditioned in a chamber for specified times at high temperatures. The exposure temperatures were 100℃∼300℃, The exposure time were 0.5 hours to 4 hours. It was found that the critical temperature was for both GFRP and CFRP reinforcing bars, 270℃. Based on the results, a linear equation for evaluation of the effect of exposure time is proposed.

Effects of ambient and elevated ~textrmCO2 and high temperature, and their interactions with zero and applied nitrogen supply (NN-no nitrogen and AN-applied nitrogen) were studied on soybean (Glycine max L.) in 2001. In this experiment, elevated ~textrmCO2 (650 ~mu~textrmmol.~textrmmol-1 ) and temperature (+5~circ ) increased total dry mass at final harvest by 125% and 119% and seed weight per plant by 57% and 105% for NN and AN plants, respectively. Although the influence of temperature and temperature x ~textrmCO2 were not significant, the influences of ~textrmCO2 concentration and temperature x ~textrmCO2 concentration were significant on total dry weight and seed weight, respectively. In particular, seed weight per plant was increased, while weight per one hundred seed weight was decreased with elevated ~textrmCO2 and temperature. The N supply increased biomass and seed weight per soybean plants. The results of this study suggest that the long-term adaptation of soybean growth at an elevated ~textrmCO2 concentration and high temperature might potentially result in a increase in dry matter production and yield.