A laser scabbling experiment was performed using a high-power fiber laser to investigate the removal rate of the concrete block and the scabbled depth. Concrete specimens with a 28-day compressive strength of 30 MPa were used in this study. Initially, we conducted the scabbling experiment under a stationary laser beam condition to determine the optimum scan speed. The laser interaction time with the concrete surface varied between 3 s and 40 s. The degree of spalling and vitrification on the surface was primarily dependent on the laser interaction time and beam power. Furthermore, thermal images were captured to investigate the spatial and temporal distribution of temperature during the scabbling process. Based on the experimental results, the scan speed at which the optical head moved over the concrete was set to be 300 mm∙min−1 or 600 mm∙min−1 for the 4.8-kW or 6.8-kW laser beam, respectively. The spalling rates and average depth on the concrete blocks were measured to be 87 cm3∙min−1 or 227 cm3∙min−1 and 6.9 mm or 9.8 mm with the 4.8-kW or 6.8-kW laser beams, respectively.

This study was designed to explore effective techniques to be used in IERW (Integrated English Reading and Writing) classes for college students. The study last for 15 weeks and included 457 students and 11 instructors at E University. The participants were freshmen who were taking a compulsory English reading and writing class, and the instructors were seven native English speakers and four Koreans. To ensure the effectiveness of IERW classes, it is important to identify what teaching activities are being used and which activities students prefer. To address these issues, the instructors were interviewed regarding their teaching activities in IERW classes. From the interview results, a survey was made that asked students which class activities they consider useful. The results show that most students responded positively to the activities that the instructors were using, with a preference of around 70 percent. Notably, pair or group activities were rated as less favorable than other activities, with a score of under 50 percent. Some implications of the findings and suggestions for teaching activities for IERW classes are provided.

A previous studies depicting origin and sequence variability of the species using DNA barcoding region with the samples collected from Korea showed relatively low sequence variability. Thus, additional markers that reveal higher variability were necessitated to scrutinize population structure in connection with dispersal and invasive dynamics among international populations. Therefore, we sequenced two complete mitochondrial genomes (mitogenomes) of M. pruinosa from the two haplotypes occurring in Korea (H1 and H3). Comparison of the two mitogenomes each with 16,312 and 16,314 bp evidenced that one region located in the A+T-rich region to provide higher number of haplotypes (4 vs. 3), sequence divergence (1.636% vs. 0.636%), and variable sites (7 vs. 3) than those of DNA barcoding region from the screening test using 13 representative individuals. This variable region, in concatenation with the currently available DNA barcoding region might be useful for population genetic analysis of worldwide populations including those of Korea. †These authors contributed equally to this paper.