As the carbon storage capacity of timber is recognized, there is growing interest in timber and wooden structures as a solution to various environmental problems. The use of Korean timber with substantial carbon storage capacity is required to reduce Korean carbon emissions and circulate timber resources. In this study, fire tests were conducted to investigate the charring properties of glued laminated timber columns made of Korean larch. The fire tests were conducted under both load-bearing and non-load-bearing conditions. The fire test results showed that the charring depth was affected by the corners of the section and that the load ratio had an insignificant influence on the charring depth when the load ratio was 0.9 or less. This study provides data that can be used to compare the charring properties of laminated wood produced using South Korean larch with the charring properties of foreign standards. This research provides reference data for developing fire-resistant design standards for timber structures made from South Korean timber.

Nowadays, diversity of materials, compositions and installation methods of Judo floor and tatami leads to a wide range of performance level of shock absorption of existing Judo floors and tatamis. In the meantime, some local and global standards on shock absorption of Judo floor and tatami have been issued and effective. However, validity and mutual adaptability of these standards are still unclear. Under the circumstances, this study aimed to examine the validity of those test methods. Finally, some official existing parameters were found to be possible candidates for expressing shock absorption level of Judo floor and tatami. In this study, in total, 23 test samples of various types and properties were manufactured as a set of imitated Judo floors. Using these test samples, sensory tests were performed in order to quantify sensory evaluation on shock absorption regarding safety of Judo athletes. The panel members of the tests were 10 university club male athletes. Using this safety evaluation scale, the validity of test methods and measured parameters was examined through the measurement and analysis of the samples. Finally, as the conclusions of this study, we clarified the followings: 1) Two types of parameters, that is, U_J and G_s measured by the test method of AJJF (All Japan Judo Federation) showed relatively good correlation with the scale of Safety, except floor samples with tatamis of very hard surface. In case of tatami of very hard surface, maximum deflection obtained from G_s raw data seems more suitable for expressing shock absorption level of Judo floor. 2) Dynamic maximum deflection, Def., measured by the test method of IJF (International Judo Federation) showed relatively moderate correlation with the scale of Safety, showing the necessity of further consideration.

Carbon emissions accelerate global warming and climate change, prompting the global development of strategies for carbon reduction. Wood, with its excellent carbon storage capacity, is a sustainable and environmentally friendly material. One cubic meter of timber can absorb 1 t of carbon dioxide and store 250 kg of carbon. This study aimed to conduct fire resistance tests on structural glue-laminated timber beams made from Korean larch (Larix kaempferi) and analyze their char properties. The specimens were fabricated with different cross-sectional shapes and areas and underwent load-bearing fire resistance tests. The results were analyzed in terms of char depth, char rate, and changes in char thickness based on the aspect ratio of the beams. In the smaller specimens, the char properties were influenced more by the width than by the length of the beam. Additionally, at a constant cross-sectional area, charring was deeper when the width was shorter than the height. The specimens did not exhibit significant differences in displacement behavior, with all specimens displaying displacements below the maximum permissible value, indicating suitable fire resistance. The findings of this study provide a foundation for research and development of fire resistance design standards for wooden structures utilizing Korean timber.

As the carbon storage capacity of timber is recognized, there is growing interest in timber and wooden structures as a solution to various environmental problems. The use of Korean timber with substantial carbon storage capacity is required to reduce Korean carbon emissions and circulate timber resources. In this study, fire tests were conducted to investigate the charring properties of glued laminated timber columns made of Korean larch. The fire tests were conducted under both load-bearing and non-load-bearing conditions. The fire test results showed that the charring depth was affected by the corners of the section, and that the load ratio had an insignificant influence on the charring depth when the load ratio was 0.9 or less. This study provides data that can be used to compare the charring properties of laminated wood produced using South Korean larch with the charring properties of foreign standards. This provides reference data for developing fire-resistant design standards for timber structures made from South Korean timber.

Korea’s steel structure fabrication plant certification system requires applicants to submit a self-assessment form before certification assessment. This study evaluated the screening effectiveness of this mandatory self-assessment and its potential for procedural simplification. All 42 new certification assessments conducted from 2021 to 2025 were analyzed across 11 assessment categories and 56 assessment subitems. The agreement and magnitude of paired subitem score differences were summarized descriptively, and discrepancies in pass/fail decisions were evaluated using an exact McNemar test. Of 2352 paired subitem scores, 2071 (88.1%) were identical. Among the 281 differing scores, 213 (75.8%) were lower in the certification assessment, and the median absolute score difference was 2.5 points. Although all 42 applications satisfied the minimum scores in self-assessment, 12 (28.6%) failed the certification assessment (p < 0.001). The self-assessment form accounts for 7 of 18 required application pages; removing it would reduce the documentation to 11 pages, a 38.9% reduction. These findings indicate limited screening effectiveness of mandatory self-assessment for identifying applications that subsequently fail certification assessment and support considering simplification of the required self-scoring form while retaining documentary evidence and certification assessment.

Maintaining consistent quality performance of recycled aggregates is essential for their reliable use in construction applications. This study evaluated whether the regulatory revision permitting concurrent appointment of quality and environmental managers affected post-certification quality test performance within Korea’s recycled aggregate certification system. Extending a previous 2025 audit-based study, this research analyzed 311 certification-application-level follow-up quality test results obtained during the 2023 national post-certification management process. Statistical analyses, including chi-square tests, Fisher’s exact tests, odds ratio comparisons, and subgroup analyses, were conducted according to management structure, personnel change status, and recycled aggregate application type. The results showed that concurrent appointment and personnel changes were not associated with statistically significant deterioration in post-certification quality test performance. In contrast, the recycled aggregate application type showed substantially greater influence on pass/fail outcomes, with relatively higher failure risks observed in concrete and fine aggregate applications requiring stricter quality control conditions. Road construction and asphalt concrete applications generally maintained relatively stable pass rates regardless of management structure or personnel continuity conditions. The subgroup analyses additionally showed that concurrent appointment did not significantly increase failure risk within any recycled aggregate application category. These findings indicate that concurrent appointment did not significantly deteriorate actual post-certification quality performance within the analyzed national certification dataset.