Reinforced concrete (RC) columns exhibit cyclic damage, such as strength degradation, under cyclic lateral loading, such as earthquakes. Considering the cyclic damage, the nonlinear load-deformation response of RC columns can be simulated using a lumped plasticity model. Based on an experimental database, this study calibrates lumped plasticity model parameters for 371 rectangular and 290 circular RC columns. The model parameters for adequate flexural rigidity, plastic rotation capacity, post-capping rotation capacity, moment strength, and cyclic strength degradation parameter are adjusted to match each experimentally observed load-deformation response. We have developed predictive equations that accurately relate the model parameters to the design characteristics of RC columns through regression analyses, providing a reliable tool for engineers and researchers. To demonstrate their application, the proposed and existing models numerically simulate the earthquake response of a bridge pier in a metropolitan railway bridge. The pier is subjected to several ground motions, increasing intensity until collapse occurs. The proposed lumped plasticity model showed about 41% less vulnerable to collapse.

Microalgae are efficient fatty acid producers owing to their high photosynthetic activities. They can act as sources of biofuel, feed, and various bioactive compounds. This study aimed to determine optimal culture conditions, including culture medium, temperature, and light intensity, to enhance the biomass and fatty acid content of the indigenous freshwater microalga, Tetradesmus obliquus. Evaluation using a high-throughput photobioreactor revealed that the optimal culture temperature and light intensity were 25°C and 300 μmol m-2 s-1, respectively. Additionally, we optimized components (N, P, and Mg) of the BG-11 medium to enhance the microalgal biomass. Modified BG-11 medium increased the T. obliquus biomass by 37% compared to the standard BG-11 medium. Subsequently, the culture medium was replaced with N- and P-depleted media to determine the abiotic stress factor that could increase the cellular fatty acid content. Notably, fatty acid content was significantly increased from 8.5% up to 14.6% on day 7 of culture in N-deficient (N-P+ and N-P-) media. Sequential optimization effectively increased the biomass by 83% and fatty acid content by >76% in T. obliquus. Our optimization method can be used to enhance the biomass and fatty acid contents of various other microalgae.

This study investigated benthic macroinvertebrates and fish in the Yeongsangang River weir and analyzed stomach contents of Squalidus chankaensis tsuchigae. Length distribution of individuals varied by site, with 91.3% and 72.7% falling within the 70-90 mm range in SC-U (upstream location of Seungchon weir) and SJ (location between Seungchon and Juksan weirs), respectively, and 77.5% within 70-80 mm and 100 mm range in JS-D (downstream location of Juksan weir). Chironomidae spp. (nonred type) were the most abundant food sources, comprising 46.3%, 76.9%, and 88.3% of the diet at SC-U, SJ, and JS-D, respectively. The Electivity Index (EI) indicated a strong preference for Chironomidae spp. (non-red type) (0.927) and avoidance for the red type (-0.929) and Limnodrilus gotoi (-0.995). The proportion of burrowers (BU) increased downstream, while swimmers (SW) decreased. The condition factor (K) varied by site, decreasing in SC-U and increasing in SJ and JS-D, showing a significant positive influence on the number of food sources (p<0.05). Among food sources, Chironomidae spp. and Baetidae sp. were predicted to be utilized across a broad range of lengths and weights, with strong connectivity observed among Tanypodinae sp., Hymenoptera sp., and Baetiella tuberculata.

Cool-season grasses are currently widely used in South Korea, but their productivity and quality may decline due to global warming associated with climate change. Warm-season grasses have shown greater adaptability to heat stress and drought conditions, making them potential alternatives for summer pasture establishment in central and southern Korea. This study aimed to compare the growth characteristics, productivity, and forage value of warm-season grasses bermudagrass and crabgrass for pasture establishment in the central region of South Korea. The experiment was conducted from May 2023 to October 2024 at the National Institute of Animal Science, Cheonan, South Korea. Crabgrass exhibited superior initial establishment and faster growth rates, whereas bermudagrass had poor initial growth, placing it at a competitive disadvantage against weeds. However, after the first cutting, bermudagrass successfully established itself and maintained a stable botanical composition. The annual dry matter productivity of crabgrass (8,586 kg/ha in 2023 and 12,013 kg/ha in 2024) was 32.62% and 40.18% higher, respectively, than that of bermudagrass (5,785 kg/ha in 2023 and 8,570 kg/ha in 2024). In forage value, crabgrass tended to show higher feed value at the initial harvest, while bermudagrass showed higher quality at the later harvests. In conclusion, these results suggest that both crabgrass and bermudagrass have potential for pasture establishment, with carbgrass being more suitable for short-term due to its rapid growth and high productivity, and bermudagrass being more appropriate for long-term due to its stable productivity in regions where overwintering in possible.

Objectives: This study aimed to evaluate the environmental awareness and health impact of respiratory diseases among residents in the exposure area (Banwoldong) and the control area. Additionally, it sought to identify the correlation between environmental factors in the exposure area and their effects on health. Methods: This study utilized a 2021 survey of 20 residents to assess environmental awareness using a 5-point Likert scale. The measurement of indoor particulate matter (PM10, PM2.5), temperature, and humidity was conducted using a direct-reading laser light scattering device, the DT-9881M (SANE Cal. Co., Ltd., Korea). Additionally, a cohort analysis was conducted using National Health Insurance Service (NHIS) data (2002~2022) to evaluate the onset of chronic disease, focusing on residency and diagnostic records. Results: In the environmental awareness assessment, women showed a statistically significantly higher level of awareness than men regarding water pollution (p=0.0039) and soil pollution (p=0.007). Also, the incidence of respiratory diseases and asthma was statistically significantly higher in the exposure area than in the control area (p<0.0001). Conclusion: This study found significantly higher rates of respiratory diseases in the exposure area compared to the control area. Long-term exposure (≥5 years) to environmental factors in the exposure area was found to be associated with a greater health impact. This suggests a strong link between environmental factors and respiratory diseases. The results emphasize the need for region-specific environmental policies to address pollution-related health disparities.

Water-soluble substances like hydrogen fluoride, generated in semiconductor manufacturing, pose serious health and environmental risks, underscoring the need for effective capture devices. Vertical liquid capture devices help by aggregating and discharging hazardous substances with water, but their design can lead to backflow during abnormal operations, causing unintended releases and impacting efficiency and safety. This study seeks to improve a vertical liquid collection device’s containment performance by optimizing its geometry. The vertical wall was rotated at various angles and directions, and turbulent kinetic energy and streamline distribution were analyzed to assess vortex formation and flow characteristics. These structural modifications identify optimal conditions to control hazardous substance migration, offering insights for future pollutant removal device designs.

본 연구는 일본잎갈나무 임분의 지위지수식을 도출하고, 지위지수별 연평균생장량의 차이 및 연평균생장량을 구할 수 있는 추정식을 도출하고자 수행되었다. 본 분석은 국가산림조사에서 일본잎갈나무림으로 판단된 표준지를 대상으로 하였으며, 이용된 표준지 개소수는 576개소였다. 지위지수는 Schumacher 모델을 적용시켜 도출하였으며, 이의 통계적 적합도는 59%였고, 편의는 –0.0002으로 아주 낮게 나타났다. 따라서 추정식은 활용에 있어 문제가 없을 것임을 확인할 수 있었다. 지위지수의 높고 낮음에 따라 연평균생장량의 평균값이 차이가 발생하는지 확인하기 위해 시도한 t-test는 5% 유의수준에서 유의성이 인정되었다. 그러므로 일본잎갈나무를 심을 때 적지적수에 조림한다면, 본 분석 결과와 같이 연평균생장량도 우수하게 될 것이다. 연평균생장량은 지위지수가 변함에 따라 발생할 수 있는 것이므로, 지위지수를 설명변수로 하는 연평균생장량 추정식이 국내 처음으로 도출되었다. 본 분석은 직선식, 곡선식, 지수식 등 5가지 수식을 적용시켰으며, 분석 결과, 식의 적합도 지수는 0.25∼0.26의 범위에 있었고, 편의는 –0.0002∼0.0016, 오차의 표준오차는 2.88∼2.92 인 것으로 나타났다. 도출된 5개 수식에 대해 지위지수를 X축으로 하는 잔차도를 그려본 결과, 잔차는 모두 “0”을 중심으로 고르게 분포하고 있어, 통계적 수치 등을 고려할 때 본 추정식은 충분히 사용 가능할 것이다.

The primary purpose of this study is to develop system modules of school buildings and the seismic loss function of the system modules for regional loss assessment of school buildings. System modules of school buildings were developed through statistical analysis of school facilities in Korea. The structural system of school buildings with non-seismic details is defined as reinforced concrete with partially masonry walls (RCPM), and 27 system modules of RCPM were developed considering the number of stories, spans, and the age of the building. System modules were designed to assess the structural behavior by applying the shear spring model and the shear failure of the columns of the school building. Probabilistic seismic demand models for each component of system modules were derived through nonlinear dynamic analysis to determine the relationship between seismic intensity, drift ratio, and peak floor acceleration of system modules. The seismic loss function was defined as the total damage ratio, which is the ratio of replacement cost to repair cost to evaluate the seismic loss quantitatively. The system module-based seismic loss well predicted the observed data. It will be possible to help many stakeholders make risk-informed decisions for a region through the regional loss assessment of school buildings in Korea.

Light-weight ceramic insulation materials and high-emissivity coatings were fabricated for reusable thermal protection systems (TPS). Alumina-silica fibers and boric acid were used to fabricate the insulation, which was heat treated at 1250 °C. High-emissivity coating of borosilicate glass modified with TaSi2, MoSi2, and SiB6 was applied via dip-and-spray coating methods and heat-treated at 1100°C. Testing in a high-velocity oxygen fuel environment at temperatures over 1100 °C for 120 seconds showed that the rigid structures withstood the flame robustly. The coating effectively infiltrated into the fibers, confirmed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction analyses. Although some oxidation of TaSi2 occurred, thereby increasing the Ta2O5 and SiO2 phases, no significant phase changes or performance degradation were observed. These results demonstrate the potential of these materials for reusable TPS applications in extreme thermal environments.

Component-specific information is crucial for identifying sources of PM2.5 in indoor environments. However, profiles of PM2.5 at various locations, including subway tunnels are limited. This study aimed to evaluate the relationships between PM2.5 and its component across tunnels, platforms, and outdoor environments at underground subway stations in Incheon. The study was conducted at six underground subway stations in Incheon. PM2.5 concentrations were measured twice at each station, simultaneously covering the tunnel, platform, and outdoor areas. Carbon (two types), ion (eight types), and metal components (20 types) were analyzed using each analytical instruments. The mean PM2.5 concentration in the tunnel was 33.0±15.7 μg/ m3, significantly higher than the concentrations observed on the platform (12.9±4.6 μg/m3) and outdoors (13.1±7.6 μg/m3). The proportion of total metal concentrations in PM2.5 was highest in the tunnel (57.8%), followed by the platform (22.2%) and outdoor areas (11.3%). Significant correlations between the platform and tunnel were observed for organic carbon, SO4 2–, NO3 –, NH4 +, Ba, Mn, Fe, and Se. Significant correlations between the platform and outdoor were observed for SO4 2–, NO3 –, NH4 +, and Ti, while the tunnel and outdoor showed correlations for SO4 2– and NH4 +. PM2.5 concentrations and total metal concentrations were highest in the tunnel. While PM2.5 concentrations on the platform and outdoors were similar, total metal concentrations were higher on the platform than outdoors. From the platform’s perspective, the concentrations of Ba, Mn, Fe, and Se were only associated with the tunnel, while SO4 2–, NO3 –, and NH4 + had tendency of correlations between both the tunnel and outdoors. The findings suggest that for platform PM2.5 concentrations, Ba, Mn, Fe, and Se may serve as indicators of tunnel-originating PM2.5, while SO4 2–, NO3 –, and NH4 + may serve as indicators for outdoor sources.

The winter forage triticale (x Triticosecale Wittmack) cultivar ‘Onggoljin’ was developed in 2018 by Central Area Crop Breeding Division, the National Institute of Crop Science, Rural Development Administration, as a winter forage. ‘Onggoljin’ has green leaves with medium length and narrower blade width compared to ‘Joseong’. ‘Onggoljin’ has shorter length spikes, a slightly longer awn than ‘Joseong’, and it’s anther without anthocyanin color. The seeds of ‘Onggoljin’ was shorter in both length and thickness than those of ‘Joseong’, with a yellowish-brown grain coat color. The heading date of ‘Onggoljin’ was at April 23 nationwide on average, two days later than ‘Joseong’. It exhibits stronger winter hardness, and simmilar lodging and desease resistance compared to ‘Joseong’. The plant height of ‘Onggoljin’ was longer than that of ‘Joseong’, and its fresh matter yield and dry matter yield were 46.31 tons/ha and 15.75 tons/ha, respectively, representing 18% and 17% higher than ‘Joseong’. The forage quality characteristics of ‘Onggoljin’ at late milky stage were crude protein content of 6.2%, neutral detergent fiber content of 59.5%, acid detergent fiber content of 34.4%, and total digestible nutrients content of 61.8%, and the silage quality was grade 2. The grain yield of ‘Onggoljin’ was 6.57 tons per ha.

The precast concrete (PC) method allows for simple assembly and disassembly of structures; however, ensuring airtight connections is crucial to prevent energy loss and maintain optimal building performance. This study focuses on the analytical investigation of the shear capacity of precast ultra-high-performance concrete (UHPC) ribs combined with standard concrete PC cladding walls. Five specimens were tested under static loading conditions to evaluate their structural performance and the thermal behavior of the UHPC rib shear keys. Test results indicated that the specimens exhibited remarkable structural performance, with shear capacity approximately three times greater than that of standard concrete. Numerical models were subsequently developed to predict the shear capacity of the shear keys under various loading conditions. A comparison between the experimental results and finite element (FE) models showed a maximum strength difference of less than 10% and a rib displacement error of up to 1.76 mm. These findings demonstrated the efficiency of the FE model for the simulation of the behavior of structures.

도로포장의 대표적 파손 종류인 균열은 일반적으로 폭이 좁고 기하학적으로 정의하기 어렵기 때문에 균열을 검출하고 유형을 분류 한 후 정량화하기까지 많은 시간이 소요된다. 본 연구의 목적은 균열 검출 이후 단계에서 요구되는 분류 및 정량화 과정을 자동화하 기 위함이다. 이를 위해, 본 연구에서는 균열이 매핑된 포장관리체계용 노면영상을 대상으로 하는 25cm 정사각형의 격자 배치 방법과 차륜 통과 영역 구분을 제시하였다. 각 격자 내 균열 객체의 길이와 진전방향, 인접한 정도 등 시각적 정보에 의한 균열 격자 속성을 정의하고 프로그래밍하여 균열 유형분류와 집계를 자동화하였다. 무작위로 수집된 고속도로 노면영상 자료를 통해 포장형식 별 주요 균열 유형을 분석하였고 차륜 통과 영역에서의 균열률 증가를 수치적으로 확인하였다.

포장상태 평가를 위한 노면영상 촬영은 라인스캔 방식이 주를 이루고 있다. 라인스캔 특성 상, 조사환경이나 장비특성이 달라질 경 우 밝기가 상이한 노면영상을 취득할 수 있고 이는 U-net과 같은 픽셀 단위 segmentation 딥러닝 모델의 균열 자동검출 성능에 영향을 미친다. 본 연구에서는 인공지능 검출 모델의 변경 없이 영상의 밝기 최적화와 morphology 연산기법을 노면영상 전·후처리 방법으로 제시하고 그 효과를 분석하였다. 영상 처리를 통해 과다 검출경향을 보인 이상치들이 제거되었으며 정답으로 간주할 수 있는 전문요 원 분석결과인 GT 균열률과의 상관성 또한 향상됨을 확인하였다.

Habitat environment and food sources of fish, benthic macroinvertebrates, and brown trout (Salmo trutta) downstream of Soyang River Dam were analyzed. Water temperature at the site where brown trout was identified ranged from approximately 12.4 to 13.4°C, confirming that this environment could provide an optimal water temperature for the growth of brown trout. Most of the riverbed structures at this site had a high proportion of cobble and pebble substrates. Brown trout constituted less than 5% of the total fish population, more abundant in the upstream. The total lengthweight relationship of brown trout showed a parameter b value of 3.234, with the condition factor (K) increasing with length. Dominant benthic macroinvertebrates were Limnodrilus gotoi and Chironomidae spp. (non-red type). Stomach content analysis indicated that brown trout primarily consumed aquatic insects (R.A., 73.8%), non-insects (R.A., 23.3%), ground insects (R.A., 2.7%), and fish (R.A., 0.2%, TL: 246 mm). Correlation analysis revealed a positive relationship between total length and species preferring flowing water (p<0.05) and a negative relationship of total length with species favoring low-flow, sandy habitats (p<0.05). Larger brown trout showed active feeding behavior and resilience to flow speed and riverbed structure. The primary food source for the largest brown trout (TL: 246 mm) was Hypomesus nipponensis. Future analyses should include brown trout with a total length of 30 cm or more. Given that samples were limited, comprehensive population management will require ongoing research.

Strong ground motions at specific sites can cause severe damage to structures. Understanding the influence of site characteristics on the dynamic response of structures is crucial for evaluating their seismic performance and mitigating the potential damage caused by site effects. This study investigates the impact of the average shear wave velocity, as a site characteristic, on the seismic response of low-to-medium-rise reinforced concrete buildings. To explore them, one-dimensional soil column models were generated using shear wave velocity profile from California, and nonlinear site response analyses were performed using bedrock motions. Nonlinear dynamic structural analyses were conducted for reinforced concrete moment-resisting frame models based on the regional information. The effect of shear wave velocity on the structural response and surface ground motions was examined. The results showed that strong ground motions tend to exhibit higher damping on softer soils, reducing their intensity, while on stiffer soils, the ground motion intensity tends to amplify. Consequently, the structural response tended to increase on stiffer soils compared to softer soils.