본 연구는 실제 복합 상수도 관망 시스템에서 서지탱크의 직경 및 설치 위치에 따른 수두 감쇠 효과를 수치해석적으로 평가하고, 천이류 분석을 통해 상수도 관망 시스템에서 수격 방지 장치로서 활용되는 서지탱크의 최적 설계 및 배치 조건을 선정하고자 하였다. 천이류 기반 수치해석은 서지탱크 해석 이론이 결합된 특성선 방법 기반 모델을 통해 실제 상수도 관망을 단순화⋅골격화한 관망 시스템을 대상으로 수행했으며, 관망 시스템에서 천이류의 영향을 크게 받는 특정 절점을 선정하여 각 절점에서 밸브 조작 조건에 따른 천이류 발생 시나리오를 설정하였다. 먼저 밸브 급폐(1.337 s) 조건의 단일 시나리오에서 서지탱크의 직경별 성능을 비교한 결과, 수두 감쇠율이 0.61%∼13.31%로 나타난 직경 0.2 m 조건이 최적 직경으로 선정되었다. 다음으로 밸브 완폐(12.033 s) 조건의 시나리오에서 선정된 직경 0.2 m 서지탱크의 설치 위치를 평가한 결과, 46개 지점 중 37번 절점에 서지탱크를 설치하는 것이 수두를 25.44%∼32.22% 감쇠시켜 본 연구 조건에서 최대 감쇠 효과를 나타냈다.

본 연구에서는 차량 충돌 시 독립기초 콘크리트 강도가 볼라드의 방호성능에 미치는 영향을 분석하였다. 이를 위해 2.5 ton 급 SUV 차량이 30 km/h의 속도로 충돌하는 실물 충돌 시험을 진행하였고, 시험 결과로부터 기초에 작용하는 충돌하중과 모멘트를 산정하였다. 이를 설계하중으로 적용하여 700×1000×300 mm 단면을 갖는 독립기초의 모델에 대한 LS-DYNA 수치해석을 수행하 였으며, 콘크리트 설계강도(21∼40 MPa)와 철근 배근 여부를 주요 변수로 설정하였다. 차량 속도 감소, 기초 상단의 변위, 균열 및 파괴 형상을 비교한 결과, 콘크리트 강도가 증가할수록 차량의 관입량이 감소하고 기초의 손상이 줄어 저항 성능이 향상되는 것을 확인할 수 있었다. 특히 철근 배근은 기초의 연성 거동이 확보되어, 전단파괴와 같은 파괴 양상이 효과적으로 제어되는 것을 확인할 수 있었다. 이러한 결과를 바탕으로 독립기초 볼라드 설계시 약 30 MPa 이상의 콘크리트 강도와 함께 적절한 철근의 배근이 필요함을 확인하였다.

본 연구는 도시지역에서 시행되고 있는 노인맞춤돌봄서비스의 예방적 돌봄 기능을 탐색하고자 수행되었다. 이를 위해 부산지역 수행기관의 전 담사회복지사 및 관리자를 대상으로 중요도-수행도 분석(IPA)을 실시하 고, IPA 결과의 해석과 맥락 이해를 보완하기 응답자 중 일부를 대상으 로 초점집단인터뷰(FGI)를 병행하였다. 연구 결과, 노인맞춤돌봄서비스는 안전·안부 확인과 정서적 지지를 중심으로 한 1차 예방 기능이 안정적으 로 수행되고 있었으며, 이는 독거노인 비율이 높은 부산의 도시적 특성 속에서 중요한 보호 체계로 작동하고 있었다. 그러나 서비스의 목적을 살릴 수 있는 전략과 운영의 미비, 특화서비스 제공의 구조적 한계 등의 문제도 함께 도출되었다. 결과를 기반으로 도시지역 노인맞춤돌봄서비스 의 예방적 돌봄 기능 강화를 위한 정책적·실천적 개선 방안을 종합적으 로 논의하였다.

This study proposes a method to improve the seismic performance of a stacked stone pagoda by applying a Ball Vibration Absorber (BVA) with a non-fixed connection. The governing equations of motion were derived by analyzing the structure's primary failure mode under seismic excitation and sliding behavior, and a numerical model was constructed. To verify the model's reliability, a shaking table experiment with a two-layer rectangular block structure was conducted, and the experimental results were compared with numerical simulations. Based on the validated numerical model, both artificial and real earthquake records were used for parametric analyses to determine the optimal design parameters that maximize the damping efficiency of the BVA system. The main findings of this study are as follows. First, when the difference between the rolling path radius and the ball radius is small, the damping performance of the BVA decreases. Still, this effect becomes negligible once the difference exceeds a certain threshold. Second, when the friction coefficient between the BVA container and the target structure is small, the non-fixed connection type exhibits superior damping performance; as the friction coefficient increases, its performance converges to that of the fixed connection type. Third, the damping performance of the BVA improves significantly as the mass of the ball increases. Fourth, the damping efficiency of the BVA is inversely proportional to the amplitude of seismic acceleration. However, its performance slightly weakens under strong ground motions; it still maintains a stable damping capacity.

In conventional construction methods, the slab-balcony junction often experiences thermal bridging. This phenomenon arises from the discontinuity of insulation materials, leading to energy loss and condensation that can compromise the structure's usability and durability. To address this issue, thermal break insulation systems were installed between the slab and balcony to effectively prevent thermal bridging and energy loss, thereby improving the overall energy efficiency of buildings. This study aims to enhance both the structural performance and thermal efficiency of slab-balcony connections in residential buildings. To assess the impact of the thermal break insulation system, two experimental specimens were prepared: one incorporating the system and the other without it. Experimental results confirmed that the inclusion of reinforcing bars significantly improved the connection's structural load-bearing capacity. Furthermore, thermal analysis revealed that the thermal break insulation system outperformed conventional insulation methods by reducing the thermal damage ratio and maintaining higher surface temperatures at the connection. In addition, a structural analysis using an FEM (finite element analysis) program was conducted to evaluate the load distribution across the specimens, demonstrating that the experimental data accurately predicted the structural behavior of the connections.

The high theoretical capacity of transition metal-based compounds makes them promising candidates for lithium-ion battery (LIB) anodes. Among them, iron selenide (FeSe2) has attracted considerable interest because of its excellent electrical conductivity and superior lithium storage capacity. However, pristine FeSe2 suffers from rapid capacity fading and structural instability during repeated cycling. Thus, this study used a facile solvothermal method to synthesize a FeSe2@rGO composite with enhanced structural integrity and electrical conductivity. By incorporating reduced graphene oxide (rGO), the composite demonstrated improved charge transfer kinetics and mechanical robustness. Morphological and structural characterizations were performed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy analyses (XPS), which confirmed the successful formation of the composite and its uniform distribution. Electrochemical properties were evaluated using cyclic voltammetry (CV), galvanostatic charge-discharge, long-term cycling, and electrochemical impedance spectroscopy. The optimized FeSe2@rGO electrode delivered a high reversible capacity of 971.95 mAhg-1 at 500 mAg-1 after 350 cycles. The underlying charge storage mechanism was investigated using scan rate-dependent CV, which revealed a dominant capacitivecontrolled contribution at higher scan rates. The study findings indicate that the FeSe2@rGO composite can serve as a high-performance anode material with excellent cycling stability and rate capability, providing a viable strategy for the development of advanced LIBs.

Incorporating nanotechnology into cement composites significantly improves mechanical properties such as strength, toughness, and durability. Graphene, with high tensile strength and large surface area, shows great promise as a nanofiller, but its hydrophobicity complicates its dispersion in cement matrices. This study used a graphene-cellulose nanofiber (G@ CNF) hybrid filler to ensure a highly uniform dispersion within the cement microstructure. The hybrid filler acts as a bridge and efficiently fills voids within the matrix. The planar structure of graphene also provides nucleation sites for hydrated products, leading to a denser microstructure. The cement composite containing 0.01 wt.% graphene exhibited a compressive strength of 72.7 MPa, representing a 47.5% improvement over the plain cement. Furthermore, the resulting cement demonstrated enhanced water resistance compared to graphene oxide-reinforced-cement. This approach offers a cost-effective and sustainable way of producing high-strength, durable cement composite.

Activated carbons with high micro-/meso-porosity derived from biomass are increasingly popular as sustainable materials. However, these carbons often struggle with low carbon content and limited structural stability. Here, we present Mongolian anthracite-based carbons synthesized via carbonization and chemical activation. Structural analysis shows that Act-MRA samples develop plate-like morphologies with reduced particle size and greater porosity as KOH content increases. The Act-MRA samples have a disordered carbon structure with small graphitic domains, even at higher KOH ratios without significant crystal defects. Notably, Act -MRA3 displays a large specific surface area and high pore volume, with welldeveloped micropores (7–20 Å) and mesopores (20–50 Å) that expand as KOH ratios rise. Electrochemical tests indicate that Act -MRA3 achieves high specific capacitance (220.6 F/g at 5 mV/s) and rate retention (~ 80% at 300 mV/s), owing to its optimized pore structure and enhanced ion transport. These findings underscore the importance of tailored pore structures and defect engineering in boosting activated carbon performance for energy storage.

Graphite crystals consist of a layered structure with stacked graphene sheets, and exhibit self-lubricating properties due to the facile sliding of graphene layers in the horizontal direction, facilitated by weak Van der Waals bonds along the c-axis. When this graphite material is impregnated with a lubricating liquid, it forms a solid and stable lubricating layer, and effectively reduces damage to the counter material from friction-induced wear under conditions of high-load reciprocating motion. This study investigates how oxidation-induced pore expansion and the silane treatment of graphite affect lubricating oil impregnation behavior, the friction coefficient of impregnated graphite, frictional stability, and microstructural changes at the friction surface. It was found that graphite oxidation within the chemical reaction temperature range enhanced porosity and increased the rate of lubricating oil impregnation. The functionalization of the graphite surface with hydrophobic silane coupling agents also significantly enhanced oil uptake, with a pronounced observed improvement when utilizing hydrophobic oils. Under a vertical load of 360 kgf and a surface pressure of 3 MPa, the graphite surface treated with hydrophobic silane and impregnated with oil exhibited the lowest average friction coefficient of 0.192 over 600 cycles. During the friction and wear process, a lubricating layer formed on the graphite surface, which contributes to stable wear performance. This surface modification strategy offers high applicability in industries such as automotive, aerospace, and heavy machinery, with the potential to significantly enhance component performance and extend service life under high-load, low-speed reciprocating conditions.

Graphene materials show great potential in the field of supercapacitors, but their tendency to agglomerate leads to a significant decrease in performance. Herein, manganese dioxide intercalated graphene oxide precursor was prepared using the modified Hummer method. During pyrolysis, manganese dioxide can not only act as a separator to prevent graphene aggregation but also undergo redox reactions with graphene to obtain oxygen-rich mesopore graphene (OMG). Benefiting from the mesoporous structure and abundant oxygen-containing functional groups, the OMG-600 electrode shows a specific capacitance of 248.67 F g− 1 at 0.5 A g− 1 and good electrochemical stability (92.25% capacitance retention after 10,000 cycles). Moreover, the assembled OMG-600//OMG-600 symmetric supercapacitor delivers an energy density of 17.69 Wh kg− 1 and superior electrochemical stabilization in 1 M Na2SO4 electrolyte.

With high redox activity, superior conductivity, abundant pores, and large specific surface area, nitrogen-doped graphitic carbon featuring a hierarchically porous structure is regarded as ideal electrode material for supercapacitors. In this work, hierarchically porous nitrogen-doped graphitic carbon (PG-PZC50) was fabricated via non-solvent induced phase separation and high-temperature calcination processes. SEM images showed its three-dimensional network structure, with abundant macro- and mesopores distributed throughout. XRD and Raman spectra confirmed the phase purity and graphitic nature of the as-prepared material, while XPS revealed its surface elemental composition, especially the content and doping states of nitrogen atoms. The graphene oxide-induced three-dimensional network, combined with the mesoporous structure of metalorganic framework-derived N-doped carbon particles, creates abundant migration channels and a large adsorption surface area for the electrolyte ions. Benefiting from its hierarchically porous structure and high nitrogen-doping content, the formed PG-PZC50 reached high specific capacitances of 499.7 F g− 1 at 0.1 A g− 1 and 179.6 F g− 1 at 20 A g− 1. Notably, the material also demonstrated robust cyclic stability with no capacitance loss after 10,000 charge–discharge cycles. The proposed synthetic strategy provides new ideas for the facile and reproducible construction of nitrogen-doped graphitic carbon with 3D hierarchically porous structure and high capacitive performances.

This research highlights the use of a WO3: CeO2@MXene/gC3N4 (MGWC) nanodisk as a versatile material. MGWC demonstrates efficient photocatalytic degradation of moxifloxacin (MOF) in water under sunlight and also shows great promise for high-performance supercapacitor applications. MGWC was synthesized using a modified hydrothermal method and thoroughly characterized using various techniques. The MGWC showed a band gap energy of 2.79 eV determined through UV–Vis DRS analysis and an average crystallite size of 39.6 nm calculated from XRD. A promising photocatalytic activity was observed for the degradation of MOF, outperforming other photocatalysts. Additionally, preliminary studies examined variations in catalyst concentration, pH, kinetics, electrolytes, scavengers, reusability, and TOC, contributing valuable insights. Under optimal conditions, the MOF achieved almost complete degradation, reaching about 99.7% within 180 min using the MGWC photocatalyst. Additionally, MGWC exhibits promising potential in supercapacitor applications. EIS and CV studies have been used to examine MGWC’s exceptional charge transfer properties. CV tests confirm the pseudocapacitive nature of MGWC electrodes. GCD studies of MGWC exhibit a high specific capacitance of 551 F/g at 1 A/g with incomparable capacitance retention of 98.1% over 10,000 cycles. This research not only aids in reducing emerging environmental pollutants but also sets the stage for sustainable energy solutions.

With the increasing demand for flexible electronic devices, smaller and lighter flexible supercapacitors have gained significant research attention. Among the various materials, self-supporting reduced graphene oxide (rGO) paper has emerged as one of the most promising electrode materials for supercapacitors due to its low cost, high chemical/thermal stability, and excellent electrical conductivity. Nevertheless, a major drawback of rGO paper is the limited ion diffusion between stacked rGO layers, hindering the effective formation of electrochemical double-layer at the electrode/electrolyte interface. In this study, we prepared the rGO paper derived from ball-milled followed-by water oxidation process for reducing the sheet size. The smaller-sized rGO sheets facilitated ion transport between graphene layers, promoting efficient electric double-layer formation. Moreover, the increased presence of edge planes in ball-milled rGO sheets achieved high capacitance, further enhancing the performance of rGO as an electrode material. Notably, the 2-BMOX rGO paper obtained from ball-milling and wet-oxidized graphite exhibited a capacitance of 117.9 F/g in cyclic voltammetry (CV) and 128.6 F/g in galvanostatic charge–discharge (GCD) tests, approximately twice that of conventional rGO. Additionally, the capacitance retained 91% of its initial performance after 2,000 cycles, indicating excellent cycling stability.

The mixed-ion electron conductor, Ag₂Se, has shown strong potential as a thermoelectric material operating near room temperature. In this study, we demonstrate that the incorporation of polyaniline (PANI) into Ag₂Se forms Ag₂Se/PANI nanocomposites with significantly enhanced thermoelectric performances. Ag₂Se was synthesized using a hydrothermal method followed by hot pressing to obtain dense composite pellets. The novelty of this work lies in the systematic tuning of the PANI content and its dual role in enhancing electrical transport while suppressing lattice thermal conductivity. Microstructural analysis reveals that PANI-induced defects, such as dislocations and point defects, effectively scatter phonons at multiple scales, resulting in a remarkably low lattice thermal conductivity (κₗ ≈ 0.08 Wm⁻1 K⁻1) at 393 K. Simultaneously, PANI improves carrier mobility by modifying the Coulomb potential at grain boundaries, reducing interfacial energy barriers. These effects lead to an improved power factor of 2028 μWm⁻1 K⁻2 and a peak figure of merit (zT ≈ 0.67) at 393 K for the 0.5 wt% PANI sample. This study introduces a novel polymer-assisted interface engineering approach to improve the thermoelectric performance of Ag₂Se-based materials.

Water contamination caused by heavy metal pollutants from industrial activities remains a pressing environmental concern. This study reports the development of a novel carbon paste electrode (CPE) modified with ethylenediaminetetraacetic acid (EDTA), polyvinyl alcohol (PVA), and multi-walled carbon nanotubes (MWCNTs) using a mechanochemical method for the electrochemical detection of Cu(II) ions. The modified electrode was thoroughly characterized to evaluate its functional groups, morphology, crystallinity, elemental composition, and electrochemical properties. Electrochemical measurements were performed using cyclic voltammetry (CV) and square-wave anodic stripping voltammetry (SWASV) under optimized conditions in 0.1 M NH₄Cl at pH 5. The EDTA/PVA/MWCNT-CPE exhibited a low detection limit (0.0457 μM), a wide linear range (0.1–2.7 μM), and excellent reproducibility (RSD = 0.51%), repeatability (RSD = 0.43%), and stability (95% retention after six days). Selectivity tests demonstrated high recovery for Cu(II) (99.7%) and Hg(II) (99.89%) with minimal interference. This simple, cost-effective sensor offers high sensitivity and selectivity, making it a promising candidate for Cu(II) detection in environmental monitoring applications.

Fluorinated carbons ( CFX) are promising cathode materials for lithium primary batteries due to their high energy density, yet suffer from poor electronic conductivity. Manganese dioxide ( MnO2), on the other hand, offers superior rate capability, but limited capacity. Here, we design MnO2/ CFx hybrid cathodes by combining MnO2 with CFX materials synthesized at controlled fluorination levels (x = 0.4–1.0) to synergistically optimize both energy and power performance. Structural and spectroscopic analyses reveal that moderate fluorination (x = 0.6) induces a favorable balance of semi-ionic C–F and interfacial O–F bonds, enhancing electron delocalization and charge transfer at the MnO2/ CFX interface. In contrast, excessive fluorination (x ≥ 0.8) leads to the formation of electrochemically inert C–F2 and C–F3 species, suppressing redox kinetics. As a result, MnO2/ CFX-0.6 delivers a discharge capacity of 390 mAh g–1−1 at 0.05 C and retains 182 mAh g–1−1 at 4 C, outperforming both pristine MnO2 and other CFX variants. This work establishes interfacial fluorine bonding configuration, not just bulk F/C ratio, as a critical design parameter for high-performance hybrid cathodes.

기후변화에 따른 관리형 화분매개자 부족은 온실 딸기 재배에서 대체 화분매개자의 필요성을 높이고 있다. 재래꿀벌(Apis cerana)은 양봉꿀벌 (Apis mellifera)의 대체종으로 제안되었으나, 온실 조건에서의 직접 비교 연구는 제한적이다. 본 연구에서는 2024년 11월부터 2025년 3월까지 대 한민국 충남 논산의 딸기 온실에 두 종의 봉군을 설치하고, 봉군세력, 먹이활동, 화분매개 효율을 모니터링 하였다. 두 종 모두 세력이 감소했으나, 양봉꿀벌에서 감소 폭이 더 컸다. 종 간 먹이활동 차이는 정오 무렵에만 나타났으며, 세력으로 보정하면 사라졌다. 꽃 방문 및 정상 수과 형성률로 측정한 화분매개 효율은 종 간 유의한 차이가 없었으나, 방문당 효율은 양봉꿀벌에서 다소 낮은 경향을 보였다. 화분매개 효율은 먹이활동과는 양의 상관을, 봉군 세력과는 음의 상관을 나타냈다. 이러한 결과는 재래꿀벌이 겨울철 봉군세력을 더 안정적으로 유지하면서도 유사한 화분매개 서비스 를 제공함을 보여주며, 온실 딸기 재배에서 대체 화분매개자로서의 잠재성을 뒷받침한다.

Hot pepper (Capsicum annuum L.) is a key vegetable crop in Ethiopia, significantly contributing to nutrition, income generation, and foreign currency earnings. However, its production faces ch allenges f rom pests and a shortage o f improved v arieties t h at o ffer acceptable y ields and quality. T his study aimed to identify varieties with higher green pod yields and quality. A field experiment was conducted at four agricultural research centers—Melkassa, Woramit, Debre Markos, and Wendogenet—and one commercial farm in Koka during 2021 and 2022. Six hot pepper genotypes (CCA-984-A, CCA-321, CCA-323, Mr. Lee no. 3 selex, Melka Awaze, and Chala) were evaluated using a Randomized Complete Block Design (RCBD) with three replications. The combined analysis of variance across locations and years revealed significant differences among the genotypes in both marketable and total yield. CCA-323 achieved the highest marketable pod yield at 225.72 q/ha, followed closely by the Chala check at 204.81 q/ha. A similar trend was noted for total green pod yield. The performance of the genotypes was highly significant (P<0.01) under both irrigation and rain-fed conditions. Additionally, significant differences genowere observed in various traits, including days to 50% flowering, plant height, plant width, pod weight per plant, pod length, pod diameter, and pod wall thickness. The CCA-323 genotype demonstrated an elongated pod shape, dark green color, smooth surface, high storability, and medium pungency, aligning well with consumer preferences in the green pod market. It proved to be a highly stable and high-yielding genotype. As a result, CCA-323 was released as ‘Koka-1’ for green pod production in the tested sites and similar agro-ecologies of Ethiopia. This variety is expected to enhance both the economic and nutritional value for hot pepper farmers and consumers and can serve as a parental line for future breeding programs.

This study investigates the dynamic characteristics of telescopic booms for special-purpose vehicles fabricated with giga-grade ultra-high strength steel (UHSS) plates that have been increasingly adopted in industrial applications. In thin-walled structures such as telescopic booms, dynamic properties – particularly natural frequencies – are critical factors directly related to structural safety. Accordingly, the dynamic characteristics were experimentally measured and analyzed for identically designed booms fabricated using either imported giga-grade steel (Strenx 960) or domestic giga-grade steel (ATOS 980), both of which are widely available in the domestic market. The natural frequencies were identified based on frequency response functions (FRFs), and the corresponding mode shapes were obtained through experimental modal analysis. The results show that the nominal yield and tensile strengths provided by the manufacturers and the measured natural frequencies and mode shapes exhibit highly similar characteristics. These experimental findings confirm that the domestic UHSS exhibits a level of dynamic performance comparable to that of the imported steel of the same grade. Consequently, the results support the feasibility of applying domestic giga-grade UHSS to telescopic boom structures and highlight its potential contribution to material localization and enhanced design competitiveness in the domestic special-purpose vehicle industry.

Small VTOL platforms envisioned for Urban Air Mobility (UAM) require compact and high–disk-loading propulsion systems, for which coaxial propellers are a suitable option. While counter-rotating coaxial propellers have been widely studied due to their torque-cancellation advantages, combined experimental and CFD-based research on coaxial co-rotating systems remains limited. This study investigates the aerodynamic performance of such a system using RANS-based CFD simulations, complemented by parallel experiments for validation. A pair of 18-inch, two-bladed propellers was arranged in a stacked layout, with mounting angle and inter-rotor spacing treated as key design variables. Results indicate that rotor–rotor interference leads to a maximum Figure of Merit (FoM) of 0.51 when the upper rotor leads at H/D = 0.07 and index angle of +15°. Increasing axial spacing generally improves the performance of both the upper and lower rotors, with the maximum thrust of 17.5N obtained at H/D = 0.07 and +45°. These performance trends were confirmed experimentally, and differences between CFD predictions and measurements remained within 5% for thrust and 6% for torque, demonstrating strong agreement. This study identifies influential design parameters for coaxial co-rotating propeller systems and provides a validated numerical methodology, offering a useful foundation for future high-efficiency Electric Distributed Propulsion System (EDPS) development.