As astroviral infection rapidly increased in the summer of 2022 in Korea, this study aimed to determine the cause and genotype of astroviruses during this period. From January to December 2022, we tested 43,312 stool samples from patients with acute gastroenteritis utilizing multiplex PCR to detect HAstV. For the HAstV-positive samples, we determined the genotypes of the HAstVs by PCR and sequencing. The monthly positive rate from 2015 to 2022 showed a notable and abrupt increase of HAstV infection between June and August 2022, peaking at 9.8% in July 2022. The annual positivity rate of HAstV remained at 2–3% between 2015 and 2019, and then decreased to 0.5% in 2020, followed by an increase to 1.5% in 2021 and 3.6% in 2022.The genotyped astroviruses in 2022 were all identified as HAstV-1 type, and the nucleotide identity% among them was >99%. The GenBank accession number for the strain genetically closest to the strains identified in our study was ON571597.1, which was HAstV-1 isolated from Pingtan in 2019. Our results provide recent epidemiological data on HAstVs in Korea. The decline and surge in astrovirus positivity in recent years may be related to the COVID-19 pandemic.

Recent studies have suggested an increased incidence of myocarditis and pericarditis following mRNA vaccination or COVID-19. However, the potential interaction effect between vaccine type and COVID-19 on heart disease risk remains uncertain. Our study aimed to examine the impact of COVID-19 status and vaccine type following the first dose on acute heart disease in the Korean population, using data from the National Health Insurance Service COVID-19 database (October 2018–March 2022). We sought to provide insights for public health policies and clinical decisions pertaining to COVID-19 vaccination strategies. We analysed heart disease risk, including acute cardiac injury, acute myocarditis, acute pericarditis, cardiac arrest, and cardiac arrhythmia, in relation to vaccine type and COVID-19 within 21 days after the first vaccination date, employing Cox proportional hazards models with time-varying covariates. This study included 3,350,855 participants. The results revealed higher heart disease risk in individuals receiving mRNA vaccines than other types (adjusted HR, 1.48; 95% CI, 1.35–1.62). Individuals infected by SARS-CoV-2 also exhibited significantly higher heart disease risk than those uninfected (adjusted HR, 3.56; 95% CI, 1.15–11.04). We found no significant interaction effect between vaccine type and COVID-19 status on the risk of acute heart disease. Notably, however, younger individuals who received mRNA vaccines had a higher heart disease risk compared to older individuals. These results may suggest the need to consider alternative vaccine options for the younger population. Further research is needed to understand underlying mechanisms and guide vaccination strategies effectively.

In 2019, the National Evidence-based Healthcare Collaborating Agency (NECA) in Korea established a health technology reassessment (HTR) system to manage the life cycle of health technologies and develop operational measures promoting the efficient use of healthcare resources. The purpose of this study is to introduce the detailed implementation process and practical functional methods of the HTR implemented by NECA.

The HTR is a structured multidisciplinary method for analyzing health technologies currently used in the healthcare system based on the latest information on parameters, such as clinical safety, effectiveness, and cost-effectiveness of optimizing the use of healthcare resources as well as social and ethical issues. All decision-making stages of the HTR are carefully reviewed and transparently managed. The HTR committee makes significant decisions, and the subcommittee decides the details related to the assessment process.

Since the pilot began in 2018, 262 cases have been reassessed, of which, 126 cases (48.1 percent) were health services not covered by the National Health Insurance (NHI). Over the past 5 years, approximately 130 recommendations for the in-use technologies were determined by the HTR committee. In the near future, it will be necessary to officially develop and establish a Korean HTR system and a legal foundation to optimize the NHI system.

Our study investigates the influence of the Korean National Pension Fund's equity ownership on voting premiums, revealing a statistically significant reduction. In particular, we establish the liquidity pathway as the primary factor among the three channels previously suggested in the literature. Analysis of the COVID-19 era and the VKospi index underscores this predominance. These findings enrich the literature on public pension funds and capital markets, providing policymakers in emerging economies with a deeper understanding of the dynamics involved in establishing pension investment institutions.

Climate change poses a major threat to marine ecosystems, with its effects felt worldwide. A major effect of climate change on marine ecosystems is the rise in water temperature, leading to a northward expansion of habitats for marine organisms. Herdmania momus, a species of ascidians (sea squirts), originally found in tropical and subtropical regions, was introduced to the Korean Peninsula. In this study, we examined the habitat of H. momus along the southeastern coast of the Korean Peninsula between 2016 and 2022. We found that H. momus settlements were observed across the entire survey area, with confirmed habitation in Busan in 2016, Ulsan in 2021, and Gyeongju (the northernmost location) in 2022. The observed habitation trend indicates a rapid geographical expansion, occurring approximately 79 years earlier than previously predicted. These observations demonstrate that marine organisms are undergoing a more rapid geographical expansion than previously projected. These unexpected findings should inform government policies related to proactive measures and strategies for managing the impact of climate change on marine ecosystems.

A new magnetic mirror machine named KAIMIR (KAIST mirror) has been designed and constructed at the Korea Advanced Institute of Science and Technology (KAIST) to study mirror plasma physics and simulate the boundary regions of magnetic fusion plasmas such as in a tokamak. The purpose of this paper is to introduce the characteristics and initial experimental results of KAIMIR. The cylindrical vacuum chamber has a length of 2.48 m and a diameter of 0.5 m and consists of three sub-chambers, namely the source, centre and expander chambers. A magnetic mirror configuration is achieved by electromagnetic coils with a maximum magnetic field strength of 0.4 T at the mirror nozzles and 0.1 T at the centre. The source plasma is generated by a plasma washer gun installed in the source chamber with a pulse forming network system. The typical discharge time is ~12 ms with a ~6 ms (1–7 ms) steady period. Initial results show that the on-axis electron density at the centre is 1019–20 m−3 and the electron temperature is 4–7 eV. Two parameters were varied in this initial phase, the source power and the mirror ratio, which is the ratio of highest to lowest magnetic field strength in the mirror-confined region. We observed that the increase of the electron density was mitigated for a source power above 0.2 MW. It was also found that the electron density increases almost linearly with the mirror ratio. Accordingly, the stored electron energy was also linearly proportional to the mirror ratio, similar to the scaling of the gas dynamic trap.

Waterproofing treatment is important for the preservation of smectite-rich rocks because of their shrinking and swelling properties. The effects of water repellents on the smectite structure and the water sorption of untreated and treated smectites were studied using X-ray diffraction. The hydrophobic Wacker BS 290 (around 100% silane/siloxane) does not prevent water from sorbing on the interlayer surface of smectite because the hydrophobic silane/siloxane is not intercalated into the interlayer space, but adsorbed onto the external surface of smectite. However, the hydrophilic Wacker BS 1001 (water-soluble emulsified silane/siloxane) prevents water from sorbing onto the interlayer surface beyond 33.3 wt.% because the hydrophobic part of the intercalated surfactant has a poor affinity for water. These results imply that water repellent containing a surfactant is suitable for smectite-rich rocks, but the expansion of smectite by intercalation of the surfactant is likely to influence volume change in smectite-rich rocks. This study notes that smectite within a rock can be one of the most important factors influencing the effectiveness of waterproof treatment. This study proposes that an intensive preliminary examination should be performed before applying water repellents to rocks, and furthermore, encourages development of new chemical reagents suitable for protecting smectite-rich rocks from moisture.

The immobilization of antimicrobial drugs can be used to expand the application of antibacterial properties to consumer products. The purpose of this study was to stabilize an antimicrobial agent, levofloxacin (LVX), for sustained antibacterial activity by immobilizing the drug molecules in a layered double hydroxide (LDH) and embedded in a polyurethane substrate. As-prepared MgAl-LDH was calcined at 400°C and reconstructed with LVX for intercalation. The X-ray diffraction patterns and cross-sectional transmission electron microscopy images showed lattice expansion along the crystallographic c axis upon LVX intercalation, suggesting successful loading of the drug. Fourier-transform infrared spectra revealed that the structure of LVX was well preserved between LDH layers. Elemental analysis indicated that the loading capacity of LVX in the hybrid was 41.7%. Bacterial-colony forming inhibitory assay on Bacillus subtilis exhibited ~100% antibacterial activity of both LVX alone and LVX-LDH hybrid (LL). To determine sustainability of antibacterial activity by the hybrid, either LVX alone or LL hybrid was loaded in the polyurethane (PU) substrate for which antibacterial activity was evaluated before and after immersion in a phosphate-buffered saline for 3 days. The LVX-composited PU showed a dramatic decrease in antibacterial activity, down to 0% after buffer treatment; LL-composited PU still contained antibacterial activity (~34% of colony suppression) after phosphate-buffered saline immersion.

The application of ceramic membranes is limited by the high cost of raw materials and the sintering process at high temperatures. To overcome these drawbacks, the present study investigated both the preparation of ceramic membranes using cost-effective raw materials and the possibility of recycling the membranes for the treatment of oily wastewater. Ceramic membranes with a pore size of 0.29–0.67 μm were prepared successfully at temperatures as low as 1000–1100°C by a simple pressing route using lowcost base materials including diatomite, kaolin, bentonite, talc, sodium borate, and barium carbonate. The typical steady-state flux, fouling resistance, and oil-rejection rate of the low-cost virgin membranes sintered at 1000°C were 2.5 × 10−5 m3m−2s−1 at 303 kPa, 63.5%, and 84.1%, respectively, with a feed oil concentration of 600 mg/L. A simple burn-out process of the used membranes at 600°C in air resulted in >95% recovery of the specific surface area (SSA) of the virgin membranes, a significantly increased steady-state flux, decreased fouling resistance, and increased oil-rejection rate. The typical steady-state flux, fouling resistance, and oil-rejection rate of the low-cost ceramic membrane sintered at 1000°C and subsequently heat treated at 600°C for 1 h in air after the first filtration were 5.4 × 10−5 m3m−2s−1 at 303 kPa, 27.1%, and 92.9%, respectively, with a feed oil concentration of 600 mg/L. The present results suggest that the low-cost ceramic membranes used for oily wastewater filtration can be recycled by simple heat-treatment at 600°C in air. As the fouling resistance of the low-cost ceramic membranes decreased with a decrease in pore size, the preferred pore size of the membranes for oily wastewater filtration is <0.4 μm.

The stability and postcritical behaviour of a horizontal flag undergoing gravity-induced deformation and periodic contact with a nearby horizontal rigid wall are experimentally investigated. The results elucidate the combined effects of gravity and contact on flutter, and reveal design principles for application to triboelectric energy harvesting. By varying the free-stream velocity, flag thickness and distance between the flagpole and the wall, the dynamics of the flag are classified into quasistatic equilibrium, flutter, partial contact and saturated contact modes. Considering the significance of gravitational effects, a new dimensionless flow velocity is proposed to identify the distribution of the dynamic modes, and its definition varies according to whether the wall is placed above or below the flag. The critical conditions for transitions between the dynamic modes are determined from the balance of fluid dynamic and gravitational effects. The distance from the flagpole to the wall is found to be more critical for transitions in the lower-wall configuration than in the upper-wall configuration. The peak contact force as well as the oscillation amplitude and frequency at postequilibrium exhibits remarkably different trends depending on the location of the wall. The peak contact force imposed on the wall by the fluttering flag weakens as the distance to the wall increases in the case of an upper wall, whereas it becomes stronger in the case of a lower wall.

In this article, we explore whether hierarchy and linearity conspire to affect agreement. The data come from an experimental study of honorific agreement between verbal si and coordinate subjects in Korean. We focus on computing the mismatch driven by honorifically mixed conjuncts. Unlike South Slavic gender agreement, Korean has neither Resolved Agreement nor First Conjunct Agreement. Only Last Conjunct Agreement is attested in Korean honorification. We show that honorific agreement within coordinate subjects is triggered only when the honorific verbal si appears, which is substantially different from the case with the honorific nominal nim. We also show that acceptability significantly decreases when the last conjunct of coordinate subjects is incongruous with an honorific verb. We thus argue that verbal honorific agreement with Korean coordinate subjects is sensitive to linear order, mimicking South Slavic gender agreement.

In this observational study conducted in 2022, 12.3% of patients who shared a room with a patient positive for severe acute respiratory coronavirus virus 2 (SARS-CoV-2) also had a positive polymerase chain reaction (PCR) test, either at initial screening or during a 5-day quarantine. Therefore, screening and quarantine are still necessary within hospitals for close-contact inpatients during the SARS-CoV-2 omicron-variant dominant period.