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.

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.

Reducing underwater radiated noise from a ship is a critical issue for ensuring the survivability of the vessel. As high-speed signal processing and interlocking algorithms become more sophisticated, the heat intensity of shipboard equipment is increasing per unit volume. When designing shipboard equipment, it is necessary to consider the trade-off between heat dissipation and noise reduction. Following an analysis of the trade-offs, it was determined that the arrangement of Fan Ass'y A and B exhibited excellent noise and heat dissipation characteristics. Based on this, PWM control operating zones were derived. It was determined that the placement of Fan Ass'y A and B in the operating zone would increase the PWM duty cycle from 33% to 58% using a signal frequency of 25kHz band with guaranteed reliability. This would increase the noise by approximately 9dB(A) but reduce the internal board reference temperature by up to 15℃.

바이오로거 외부 부착방법이 점농어 Lateolabrax maculatus(평균 체중 2630.8 g)의 혈액 특성과 바이오로거 부착효율에 미치는 영향을 조사하기 위해 바이오로거 미부착구(대조구), anchor attachment (AA), monofilament attachment (MA) 및 silicon tube attachment (SA) 방식의 4가 지 실험구를 설정하였다. 바이오로거 부착 후 1, 7, 14, 28, 56 및 84일에 혈액성상과 바이오로 거 부착효율을 조사하였다. 혈액 내 hematocrit, Na+, Cl-, GPT, total protein 농도 및 superoxide dismutase 활성은 바이오로거 외부 부착방법에 영향을 받지 않았다(p>0.05). AA 그룹의 GOT (부착 1일), hemoglobin(56일) 및 total cholesterol(56일 및 84일)와 MA 그룹의 glucose와 cortisol (14일) 및 total cholesterol(84일) 농도는 대조구에 비해 유의하게 높았다(p<0.05). 실험 기간 동안 SA 그룹의 모든 혈액 특성은 대조구와 차이가 없었다(p>0.05). AA, MA 및 SA 그룹 의 바이오로거 부착효율은 부착 84일 후 각각 0.0%, 33.3%, 그리고 100.0%였다. 이상의 결과 에서 최적의 외부 바이오로거 부착방법은 SA 유형으로 나타났으며, 점농어의 생체원격측정 기술 개발을 위한 기본 정보로 활용될 수 있을 것이다.

We report the effect of plastic deformation on the thermoelectric properties of n-type Bi2Te2.5Se0.5 compounds. N-type Bi2Te2.5Se0.5 powders are synthesized by an oxide-reduction process and consolidated via sparkplasma sintering. To explore the effect of plastic deformation on the thermoelectric properties, the sintered bodies are subjected to uniaxial pressure to induce a controlled amount of compressive strains (-0.2, -0.3, and -0.4). The shaping temperature is set using a thermochemical analyzer, and the plastic deformation effect is assessed without altering the material composition through differential scanning calorimetry. This strategy is crucial because the conventional hotforging process can often lead to alterations in material composition due to the high volatility of chalcogen elements. With increasing compressive strain, the (00l) planes become aligned in the direction perpendicular to the pressure axis. Furthermore, an increase in the carrier concentration is observed upon compressive plastic deformation, i.e., the donorlike effect of the plastic deformation in n-type Bi2Te2.5Se0.5 compounds. Owing to the increased electrical conductivity through the preferred orientation and the donor-like effect, an improved ZT is achieved in n-type Bi2Te2.5Se0.5 through the compressive-forming process.

Al2O3 has excellent sintering properties and is important in semiconductor manufacturing processes that require high-temperature resistance and chemical inertness in a plasma environment. In this study, a comprehensive analysis of the chemical characteristics, physical properties, crystal structure, and dispersion stability of three commercially available Al2O3 powders was conducted. The aim was to provide a technological foundation for selecting and utilizing appropriate Al2O3 powders in practical applications. All powders exhibited α-Al2O3 as the main phase, with the presence of beta-phase Na2O-11Al2O3 as the secondary phase. The highest Na+ ion leaching was observed in the aqueous slurry state due to the presence of the secondary phase. Although the average particle size difference among the three powders was not significant, distinct differences in particle size distribution were observed. ALG-1SH showed a broad particle size distribution, P162 exhibited a bimodal distribution, and AES-11 displayed a uniform unimodal distribution. Highconcentration Al2O3 slurries showed differences in viscosity due to ion release when no dispersant was added, affecting the electrical double-layer thickness. Polycarboxylate was found to effectively enhance the dispersion stability of all three powders. In the dispersion stability analysis, ALG-1SH exhibited the slowest sedimentation tendency, as evidenced by the low TSI value, while P162 showed faster precipitation, influenced by the particle size distribution.

With the increasing demand for electronic products, the amount of multilayer ceramic capacitor (MLCC) waste has also increased. Recycling technology has recently gained attention because it can simultaneously address raw material supply and waste disposal issues. However, research on recovering valuable metals from MLCCs and converting the recovered metals into high-value-added materials remains insufficient. Herein, we describe an electrospinning (E-spinning) process to recover nickel from MLCCs and modulate the morphology of the recovered nickel oxide particles. The nickel oxalate powder was recovered using organic acid leaching and precipitation. Nickel oxide nanoparticles were prepared via heat treatment and ultrasonic milling. A mixture of nickel oxide particles and polyvinylpyrrolidone (PVP) was used as the E-spinning solution. A PVP/NiO nanowire composite was fabricated via Espinning, and a nickel oxide nanowire with a network structure was manufactured through calcination. The nanowire diameters and morphologies are discussed based on the nickel oxide content in the E-spinning solution.

우리나라 여러 해양환경 지역으로부터 확보한 370주의 해양세균, 균류, 미세조류로부터 기초생 리활성(항산화, 항염, 항균, 항암, 항바이러스)을 조사하여 채집지, 분리원, 종(種) 수준에서의 활성결과를 비교하였다. 해양세균의 경우, 일반적으로 유용성이 많이 알려진 Streptomyces 속 과 Bacillus 속에 속하는 균주들이 두드러진 강한 효능이 관찰되었고, 주로 해양퇴적물로부터 유용한 자원을 분리할 수 있었다. 해양균류와 미세조류의 경우에도 종 특이적으로 활성이 강 하게 나타나는 결과를 확인할 수 있었고, 효능 특이적으로 활성을 보이는 결과도 얻을 수 있었 다. 이러한 결과를 바탕으로 추후 특정질병에 선택적으로 효능을 보이는 화학물질 연구 또는 자원 기반 연구 수행 시 유용성을 전제로 한 자원 확보 전략 수립과 산업 활성화를 위한 전 략소재로 우선적 접근이 용이할 수 있는 연구결과라 생각된다. 또한, 이들 결과를 해양바이오 뱅크를 통한 분양소재로 활용함으로써 학계, 산업계에서 활용하여 해양바이오산업 활성화에 좀 더 빠른 접근을 도울 수 있다고 생각한다.

본 연구는 낙엽활엽수종인 이팝나무(Chionanthus retusa) 잎의 흡음 성능을 평가하고자 하였다. 잎을 주재료로 하여 재료의 크기와 두께 및 건조 조건을 달리해 흡음재를 제조하였다. 중간형 측정관(100㎐-3200㎐)을 적용한 관내법(Impedance tube method)을 이용하여 흡음율을 측정하였 다. 총 18개의 조건에서 측정된 흡음율을 분석하였다. 기건엽 조건(MC 13.92%)과 생엽 조건(MC 162.04%)의 흡음율은 두께가 증가함에 따라 크게 향상되었다. 흡음율은 밀도의 증가에 비례하는데, 부피당 밀도가 더 높은 생엽조건의 두께별 흡음율이 더 높게 나타났다. 생엽 조건군에서 크기 0.5 × 0.5㎠의 2.50㎝ 두께에서 평균 흡음율은 0.643으로 가장 높게 나타났으며, 각 시험처리 조건별 흡음재의 주파수 대역별 흡음율은 기건엽 조건의 두께 1.75㎝에서 가장 높게 나타났다. 이상의 연구결과로부터 전반적인 흡음율은 1000㎐ 이상의 대역에서 더 높은 성능을 보였다.

하구와 연안역은 조석주기에 따라 수층 혼합과 해수 유동이 활발하므로 보다 정확한 수질측정 결과를 얻기 위해서는 조 석조건을 고려해서 시료를 채취해야 한다. 우리나라 해양환경공정시험기준에서는 평균적인 상황에 대한 자료를 확보하고자 조석중간 에 시료 채취를 권장하는 반면, Kaplovsky(1957), Fortune and Mauraud(2015) 등 다수의 해외 연구에서는 간조 또는 만조와 같은 정조시 조사할 것을 권장한다. 또한 국내 해양환경정책의 수립과 평가에 활용 중인 해양환경측정망 자료의 조석효과를 파악하기 위해 2014~2020년 마산만 조사결과를 정조시와 조석중간 두 그룹으로 나누어 분석한 결과, COD, TN, TP 등 주요 해양환경지표의 두 그룹 간 수질측정값 간 차이가 있음을 확인했다. 해양환경측정망은 연안오염총량관리을 비롯한 다양한 해양환경정책의 계획수립, 목표설정 및 평가에 활용되는 만큼 정도관리가 중요하다. 이를 위해서 해양환경측정망 자료 항목으로 조석정보를 추가하고, 같은 조석조건하의 조사를 단계적으로 확대해 갈 것을 제안한다.

One-dimensional MgO nanostructures with various morphologies were synthesized by a thermal evaporation method. The synthesis process was carried out in air at atmospheric pressure, which made the process very simple. A mixed powder of magnesium and active carbon was used as the source powder. The morphologies of the MgO nanostructures were changed by varying the growth temperature. When the growth temperature was 700 °C, untapered nanowires with smooth surfaces were grown. As the temperature increased to 850 °C, 1,000 °C and 1,100 °C, tapered nanobelts, tapered nanowires and then knotted nanowires were sequentially observed. X-ray diffraction analysis revealed that the MgO nanostructures had a cubic crystallographic structure. Energy dispersive X-ray analysis showed that the nanostructures were composed of Mg and O elements, indicating high purity MgO nanostructures. Fourier transform infrared spectra peaks showed the characteristic absorption of MgO. No catalyst particles were observed at the tips of the one-dimensional nanostructures, which suggested that the one-dimensional nanostructures were grown in a vapor-solid growth mechanism.