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 Allium microdictyon in forest cultivation on leaf growth characteristics and antioxidant activity.Methods: One-year seedlings of Allium microdictyon 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 Allium microdictyon. 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.

Background: Angelica gigas Nakai, that belong to the Umbelliferae family, is one of the traditional medicinal plants in Korea. Its roots have been used to treat gynecological diseases. In this study, growth characteristics and index components were compared with the forest microclimate at several forest sites. Methods and Results: A. gigas was planted in three climatic zones according to the temperature (southern temperature zone - Hamyang, central temperature zone - Bonghwa, and northern temperature zone - Jeongseon) and growth characteristics were investigated in comparison with the forest microclimate. Our results indicated that the root diameter and length, and fresh and dry weight were the highest in Jeongseon. The total content of decursin was the highest in Jeongseon (9.52%), followed by those in Hamyang (8.07%) and Bonghwa (7.48%), respectively. Additionally, the yield of decursin (1.39 g) was the highest in Jeongseon. Conclusions: The yield and index components were influenced by the microclimate in the forests, and it was assumed that high altitude and low temperature affected the increase in growth and index components. These results will be useful as basic data to study the correlation among environmental conditions, growth, and index components.

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.

Dust exposure is a serious threat to human health due to dermal contact, inhalation, and ingestion. Children are more vulnerable to dust than adults as a result of high rates of unintentional, or deliberate, ingestion and inhalation of dust. In this study, dust reduction in the playground due to coating of the soil particles with a PVA/PVAc-based solution was investigated. Soil particles were coated with varying amounts of coating solution and the samples were examined for various parameters e.g., specific density, moisture content, liquid and plastic limits, permeability, dust generation due to wind effect and human activity. The results demonstrated that coated soil samples showed improved permeability characteristics and reduced dust generation. These characteristics were improved by increased content of coating solution.

Recent climate change-driven warming and prolonged drought have reduced fuel moisture in forests, increasing the frequency and severity of wildfires. In particular, crown fires have become more frequent, highlighting the importance of quantifying crown fuel characteristics. However, studies on the crown fuel biomass of Pinus densiflora in South Korea remain limited. This study aimed to quantify crown fuel biomass and develop a diameter at breast height (DBH)-based allometric model across major P. densiflora distribution areas. A total of 67 sample trees were destructively sampled across seven regions. Crown fuel components were classified into needles and branch diameter classes, and their dry biomass was measured. A log-transformed allometric model was developed, and its reliability was evaluated using correction factors, confidence intervals, and prediction intervals. Branches accounted for approximately 78% of total crown fuel, while needles accounted for approximately 22%. The model demonstrated high explanatory power, with $R_{adj}^2$ ranging from 0.783 to 0.945. Combustible fuels (≤1.0 cm) accounted for approximately 45% of total crown fuel. The developed model can be used as an input for wildfire spread prediction and provides a basis for crown fire risk assessment and fuel mapping.