This study examined the influence of multiple factors—particularly occupant presence and air purifier operation—on indoor PM2.5 concentrations across 104 households in the Seoul metropolitan area. Both indoor and outdoor PM2.5 concentrations were continuously monitored and integrated with time-specific survey data to analyze spatial and temporal patterns of indoor exposure. Results showed that occupant presence significantly elevated indoor PM2.5 concentrations, especially during periods of high activity (08:00~15:00 and 18:00~20:00). The indoor/outdoor (I/ O) concentration ratio was also significantly higher during these periods, indicating that occupant activities were a major contributor to indoor PM2.5 concentrations. Air purifier use was found to be associated with a consistent reduction in indoor PM2.5 concentrations, regardless of occupancy status. Notably, the I/O ratio also decreased when air purifiers were in operation, demonstrating their effectiveness in controlling both indoor emissions and the infiltration of outdoor pollutants. These findings provide empirical evidence of the multifactorial dynamics governing indoor PM2.5 exposure and highlight the importance of occupant-centered and time-specific strategies for effective residential air quality management.

This study aims to examine the validity of current environmental safety standards and propose necessary improvements to minimize health risks posed by heavy metals in children’s activity zones. Compared to adults, children are more vulnerable to hazardous substances, and exposure to heavy metals can severely impact their neurological development and physical growth. In Korea, the amendment of the Enforcement Rules of the Environmental Health Act (Annex 4-20) in July 2021 reduced the acceptable threshold for lead (Pb) in paints and finishing materials used in children’s activity zones. However, regulatory standards for other heavy metals remain insufficient. Therefore, this research investigates and analyzes both domestic and international standards for heavy metals in commonly used materials such as wallpaper, flooring, finishing materials, and paints. This paper proposes guidelines for improving current regulatory criteria based on scientific validity and potential exposure. The findings are expected to serve as foundational data for advancing proactive environmental safety management strategies to better protect children’s health.

본 연구는 규사 기반의 표면처리 기법이 FRCM 복합체의 인장 성능에 미치는 영향을 정량적으로 평가하고자 수행되었다. 실험은 탄소 및 내알칼리성 유리 직물을 사용하여 표면처리 유무를 변수로 설정하였으며, 총 4개의 실험군(CN, CS, GN, GS)에 대해 인장 실험을 수행하였다. 실험 결과, 탄소 직물을 적용한 복합체는 유리 직물 대비 우수한 인장 성능을 나타냈으며, 특히 표면처리된 탄소 실험군(CS)은 비처리 실험군(CN) 대비 약 73.7%의 인장강도 향상과 66.9%의 인성 증가를 보였다. 또한 유효계수(COE) 분석을 통해 직물의 기계적 성능이 복합체에 기여하는 정도를 정량화하였으며, 표면처리가 계면 부착 성능 및 응력 전달 효율 향상에 기여함을 확인하였다. 이를 통해 FRCM 복합체가 실구조물에 적용될 경우 일체화된 거동 확보를 기반으로 구조적 성능의 향상 등의 보강 효과를 기대할 수 있는 기술적 가능성을 제시하였다. 본 연구는 FRCM 복합체의 표준화 및 성능 향상을 위한 기초 자료를 제공하며, 향후 실 구조물 적용 및 수치해석 모델링의 신뢰성 제고에 기여할 수 있을 것으로 판단된다.

Natural populations of numerous species have decreased sharply in recent years, and a number of mammalian species are also now at elevated risk of extinction globally. The long-tailed goral Naemorhedus caudatus, a vulnerable and protected species designated by IUCN (International Union for Conservation of Nature) and CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora), is distributed in Northeast Asia including the Korean Peninsula. In South Korea, the Seoraksan National Park is known as the largest core habitat for the long-tailed goral population. In this study, phylogenetic relationships and population genetic features of the Seoraksan goral population were analyzed using fecal samples with both mitochondrial DNA and microsatellite markers. We found that Seoraksan gorals were the most closely related to Russian population, and also found that a unique Seoraksan lineage evolved there. In addition, the Seoraksan goral population showed higher genetic diversity than other South Korean populations, suggesting that this population might represent the most ecologically and evolutionarily important remnants of the long-tailed goral in South Korea. The Seoraksan goral population had a low level of genetic differentiation and a rather single genetic structure, suggesting that non-negligible levels of gene flow might have occurred across populations. Moreover, microsatellite genotype-based individual identification estimated that the population size was ≥81 in the Seoraksan National Park. Findings of our study suggest that effective conservation and restoration actions are needed for long-term conservation of N. caudatus in this protected area.

복숭아혹진딧물(Myzus persicae Sulzer, Hemiptera: Aphididae)은 채소작물, 과수작물과 화훼작물에 발생하여 농업과 원예작물에 경제적 피해를 주는 주요 해충이다. 복숭아혹진딧물과 기주내부 미생물간의 상호작용을 이해하기 위해, 격리된 사육시설에서 약 2년간 누대사육된 복숭아 혹진딧물 내의 미생물 군집구조는 16S rRNA gene을 이용하여 분석하였다. 복숭아혹진딧물에 우점하는 미생물은 γ-proteobacteria에 속하는 Buchnera sp., Pseudomonas sp., Propionibacterium sp. 등이 주요 우점하는 것을 확인되었다. 미생물 군집크기분석은 정량 PCR을 통해 분석하였 으며, 박테리아 군집의 크기가 곰팡이 군집보다 약 4,300배 큰 것을 확인하였다. 이러한 결과로부터 복숭아혹진딧물 내부에는 γ-proteobacteria 에 속하는 Buchnera sp.가 기주와 매우 밀접한 상호관계가가 이루어진다고 판단되어진다. 본 연구의 결과는 복숭아혹진딧물과 기주내부 미생물간 의 상호작용을 이해하는데 기초자료로 제공될 수 있을 것으로 기대된다.

산업 발전에 따라 도로 연장이 지속적으로 증가하면서 폐 아스팔트 발생량이 늘어나자, 국내에서는 순환골재를 의무적으로 사 용하도록 관련 규정을 마련하였다. 현장 플랜트에서 순환 아스팔트 혼합물을 생산할 때 재생첨가제를 투입해야 하는 경우, 국 토교통부 “아스팔트 콘크리트 포장 시공 지침“에서는 재생첨가제와 아스팔트를 동시에 투입하도록 명시하고 있다. 그러나 혼합 시간이 부족하거나 혼합 과정이 불량할 경우, 재생첨가제가 균일하게 분산되지 않아 혼합물 품질이 저하될 우려가 있다. 이에 본 연구에서는 기존의 건식 혼합 방식에서 발생하는 문제점을 해소하고자, 아스팔트 플랜트의 Pre-Mixer를 활용하여 아스팔트 바인더와 첨가제를 사전에 혼합하고, 혼합 시간을 달리한 시료를 추출하여 DSR(Dynamic Shear Rheometer) 장비를 통한 MSCR 시험을 수행하였다. 그 결과, 혼합시간이 증가함에 따라 Jnr 값은 증가하고, %Recovery 값은 감소하는 경향이 확인되었 으며, 혼합 시간이 바인더 특성 변화에 유의미한 영향을 미치는 것을 확인하였다. 추가적으로 t-검정을 통해 이러한 경향의 통 계적 유의성을 검증한 결과, Jnr 값은 3-5분, 7-9분, %Recovery 값은 1-3분, 3-5분, 7-9분 구간에서 p값이 0.05 이상으로 나타 나 통계적으로 유의미한 차이가 없었다.

In this paper, the design feasibility of the high-temperature rotation test jig for the operating state of gas turbine blades was confirmed through thermal structural analysis and modal analysis. The structural analysis model was composed of assembled blade, disc, cover, and shaft. Here, the disc was designed to be assembled with two types of blade. First, thermal analysis was performed by applying the blade surface temperature of 800°C. Next, structural analysis was performed at 3600 RPM, the normal operating condition, and 4320 RPM, the overspeed operation condition. Lastly, modal analysis was performed to examine the natural frequency and deformation of the jig. The FE analysis showed that the temperature decreased from the blade to disc dovetail. Additionally, both the blade and disc showed structural stability as the maximum stress was below the yield strength. Also, the first natural frequency was 636.35Hz and 639.43Hz at 3600RPM and 4320RPM, respectively, satisfying gas turbine design standards and guidelines. Ultimately, the designed test jig was confirmed to be capable of high temperature and rotation testing of various blades.

Biodiversity encompasses species diversity, which includes species richness and species evenness. High species diversity is known to contribute to community stability and the potential for maintaining healthy ecosystem functioning. However, the most commonly used species diversity indices have some limitations, as they require species-specific abundance data for each community. In contrast, phylogenetic diversity measures the evolutionary distances between species within a community, reflecting ecological and/or evolutionary divergences and niche differences, without requiring abundance data. This study assessed biodiversity by calculating phylogenetic diversity indices for freshwater fishes (19 species) and aquatic insects (49 species) at three sites within Seoraksan and Odaesan National Parks. The aquatic insects studied belong to the EPT group (Ephemeroptera, Plecoptera, and Trichoptera), which are widely used as bioindicators of aquatic ecosystems. Two mitochondrial DNA genes were used as molecular markers: COI and cyt b for fish, and COI and 16S rRNA for the EPT - group. Overall, Odaesan National Park exhibited higher phylogenetic diversity in both fishes and aquatic insects compared to Seoraksan National Park, although this difference was not statistically significant. The highest phylogenetic and species diversity were observed for fish at the OD2 site (Woljeong District) and for the EPT group at the OD1 (Gyebangsan) and SA2 (Jangsudae) sites. Correlation analysis revealed that phylogenetic diversity indices were more positively associated with species richness than species diversity indices. This study serves as a pilot project for establishing standardized methods for assessing biodiversity in national park habitats using phylogenetic diversity. It also aims to inform various policies, such as the development of biodiversity assessment systems and the prioritization of protected areas within national parks.

Solar energy has been recognized as an alternative energy source that can help address fuel depletion and climate change issues. As a renewable energy alternative to fossil fuels, it is an eco-friendly and unlimited energy source. Among solar cells, thin film Cu2ZnSn(S,Se)4 (CZTSSe) is currently being actively studied as an alternative to heavily commercialized Cu (In,Ga)Se2 (CIGS) thin film solar cells, which rely upon costly and scarce indium and gallium. Currently, the highest efficiency achieved by CZTSSe cells is 14.9 %, lower than the CIGS record of 23.35 %. When applied to devices, CZTSSe thin films perform poorly compared to other materials due to problems including lattice defects, conduction band offset, secondary phase information, and narrow stable phase regions, so improving their performance is essential. Research into ways of improving performance by doping with Germanium and Cadmium is underway. Specifically, Ge can be doped into CZTSSe, replacing Sn to reduce pinholes and bulk recombination. Additionally, partially replacing Zn with Cd can facilitate grain growth and suppress secondary phase formation. In this study, we analyzed the device’s performance after doping Ge into CZTSSe thin film using evaporation, and doping Cd using chemical bath deposition. The Ge doped thin film showed a larger bandgap than the undoped reference thin film, achieving the highest Voc of 494 mV in the device. The Cd doped thin film showed a smaller bandgap than the undoped reference thin film, with the highest Jsc of 36.9 mA/cm2. As a result, the thin film solar cells achieved a power conversion efficiency of 10.84 %, representing a 20 % improvement in power conversion efficiency compared to the undoped reference device.

This study investigated the characteristics of personal PM2.5 exposure among 109 participants residing in Seoul over a two-month period, from February 2024 to April 2024. The participants were categorized into four sub-populations, and personal exposure to PM2.5 was assessed using portable monitors, GPS, and time-activity diaries. To understand the time-activity patterns, the daily occupancy rate for different microenvironments was calculated. Additionally, daily PM2.5 exposure contribution and integrated exposure were quantified. A time series analysis was conducted to identify differences in time-activity patterns and PM2.5 exposure among the sub-populations. ANOVA analysis indicated statistically significant differences in PM2.5 concentrations across populations and microenvironments (p<0.05). However, post-hoc analysis revealed specific microenvironments within certain sub-populations where PM2.5 concentration differences were not significant (p>0.05). All sub-populations spent more than 90% of their time indoors, and the results for exposure contribution and integrated exposure indicated that the home, which had the highest occupancy rate, was the most significant contributor to PM2.5 exposure. This study is expected to serve as foundational data for future indoor air quality management and the development of personalized strategies for reducing PM2.5 exposure.