This work focused on reflecting the substituting ratio of fine aggregate in an aggregate simulation. The existing simulation studies showed superior performance on generating the particles; however, the studies did not and could not reflect the substituting ratio of fine aggregate. Therefore, a statistical approach with the Monte Carlo simulation method was tried to improve the lacking part. According to the fitting of the distributions, the Cauchy distribution was best for the natural sand and the log-normal distribution was best for the substituting materials. The chosen two distributions were mixed and applied, using the Monte Carlo method with the mixed model, rather than the existing particle generation formula of the simulation. The substitution ratio was considered to be 0, 30, 50, 70, 100%. The fraction of small particles was gradually increased by the substituting ratio. As a result, the simulated particle distribution reflected well the statistical model. In addition, the simulation was almost the same as that of real particle distribution, according to the CT scanning.

High temperature conditions, such as fire, are detrimental factors to the mechanical and chemical properties of concrete. In this paper, the authors developed a new type of coarse aggregate, named PCM/SiC composite aggregate (enhanced aggregate: EA), to improve fire-resistance performance. To investigate the validity of EA for construction materials, a compressive strength test, static modulus of elasticity, X-ray diffraction (XRD), and scanning electron microscopy (SEM) were conducted. In addition, this EA has been developed to improve residual performance after exposure to high temperature, with residual compressive strength and internal temperature measurement tested at 1000 °C. Furthermore, chemical properties after heating were investigated by XRD and SEM-EDAX. The results show that the percentage of residual compressive strength of heated concrete with EA is higher than plain concrete. The concrete with EA exhibited primary cement composites such as C-H and C-S-H after exposure to high temperature through XRD and SEM-EDAX. On the other hand, major hydration products could not be observed in plain concrete. PCM and SiC offer an opportunity to delay the increase in concrete temperature. From evaluation of the results, we can see that EA enhanced the residual performance of concrete after exposure to high temperature conditions.

Background and objective: This study was conducted to investigate the effect of the cultivation environment of <i>Allium microdictyon</i> in forest cultivation on leaf growth characteristics and antioxidant activity.Methods: One-year seedlings of <i>Allium microdictyon</i> were planted in test sites with different elevations and slopes in a forest. Each test site was selected on the south-facing slope and north-facing slope each at 700 m and 500 m above sea level, and each test site was created within a straight-line distance of 200m. Leaf characteristics were investigated and antioxidant enzyme activity were measured from April to June the following year after planting.Results: The 500m sites reached the maximum leaf size about a week earlier than the 700m sites, and the maximum leaf area was doubled in the same periods and higher in the south-facing slope than the north-facing slope. In the south-facing slope in Misan-ri, where the growth was the fastest, the total nitrogen (T-N) in soil also showed a high content. Regarding the antioxidant activity according to the planting site and harvest time, there was little difference in superoxide dismutase (SOD), but catalase increased until the time of release and then decreased thereafter. Malondialdehyde (MDA), a measure of the degree of lipid peroxidation, decreased until the harvest date and then slightly increased.Conclusion: Based on the results of this study, it is possible to control the harvest date by adjusting the location environment such as the slope direction of the sites for forest cultivation of <i>Allium microdictyon</i>. Catalase and MDA tended to be proportional or inversely proportional depending on the harvest date, serving as most active indicators of change in physiological activity.