This study explores the importance of critical raw materials and minerals by analyzing the Republic of Korea’s recent circular economy and resource security policy. Raw materials and rare metals are becoming increasingly significant to the Korean economy because the country is currently shifting away from fossil fuels and nuclear power towards renewable energy resources as well as transforming its industries towards decarbonization, digitization, and automation. Korea is a resource-poor country and is heavily dependent on imported minerals and rare earths, which are essential for its economy and new industry. Responding to these challenges and concerns, Korea is moving towards a sustainable circular economy and achieving greater resource security. Despite certain limitations, this transition would ultimately contribute in preparing Korea for current and future challenges in the areas of critical raw materials and minerals.

Global navigation satellite systems (GNSSs) provide a common positioning method that utilizes satellite signals to determine the spatial location of a receiver. However, there are several error factors in standalone GNSS positioning due to instrumental, procedural, and environmental factors that arise during the signal transmission process, and the final positioning error can be up to several meters or greater in length. Thus, real-time kinematic (RTK) correction and post-mission precise point positioning (PPP) processing technologies are proposed to improve accuracy and accomplish precise position measurements. To evaluate the geolocation accuracy of mosaicked UAV images of an abandoned mine site, we compared each orthomosaic image and digital elevation model obtained using standalone GNSS positioning, differential (RTK) GNSS positioning, and post-mission PPP processing techniques. In the three types of error evaluation measure (i.e., relative camera location error, ground control points-based absolute image mapping error, and volumetric difference of mine tailings), we found that the RTK GNSS positioning method obtained the best performance in terms of the relative camera location error and the absolute image mapping error evaluations, and the PPP post-processing correction effectively reduced the error (69.5% of the average total relative camera location error and 59.3% of the average total absolute image mapping error) relative to the standalone GNSS positioning method. Although differential (RTK) GNSS positioning is widely used in positioning applications that require very high accuracy, post-mission PPP processing can also be used in various fields in which it is either not feasible to operate expensive equipment to receive RTK GNSS signals or network RTK services are unavailable.

The occurrence and fate of antibiotic compounds in the aquatic environment has been recognized as an emerging area of interest in environmental chemistry. An analytical method was developed and validated for determining β-lactam and polyether ionophore antibiotics in surface water, urban wastewater, and sediment based on solid-phase extraction (SPE) and liquid chromatography–ion trap tandem mass spectrometry (LC-MS-MS). The average recovery of β-lactams and polyether ionophores from all the fortified samples was generally higher than 80% (except for amoxicillin and ampicillin). A total of 400 actual water and sediment samples were analysed using SPE-LC-MS-MS to evaluate the occurrence and fate of these antibiotic compounds in a river and a wastewater treatment plant in northern Colorado. Most samples were found to be negative for β-lactam compounds. In those samples with positive results, β-lactam compounds were found at 15–17 ng/L in influent wastewater samples, 9–11 ng/L in surface water samples, and 0.13–0.36 μg/kg in sediment samples. No β-lactam compounds were detected in any effluent wastewater samples. The β-lactams are expected to be easily eliminated in wastewater treatment plants due to the lability of the β-lactam ring towards chemical and microbial degradation. The average concentration of ionophores ranged 0.03–0.05 μg/L in surface water samples and 0.5–3.1 μg/kg in sediment samples. These results confirm that β-lactam and ionophore antibiotics are adsorbed by sediment.