This study investigates the seismic performance of beam-column connections using Thin-Walled Steel Composite (TSC) beams and Prestressed Reinforced Concrete (PSRC) columns. TSC beams are constructed from U-shaped thin steel plates that are filled with concrete, allowing for composite action with slabs through the use of shear connectors. They are widely applied in industrial buildings due to excellent strength, stiffness, and constructability. However, slender web plates are prone to local buckling, which may compromise their performance during seismic events. To mitigate this issue, internal supports have been introduced to enhance web stability and concrete confinement. Cyclic loading tests on three specimens—with and without internal supports—demonstrated that the supports increased moment capacity, improved energy dissipation, and effectively reduced buckling. Even slender sections demonstrated performance comparable to that of compact sections. All specimens reached peak strength at a 2.44% rotation angle, with damage localized near the supports. A practical connection detail was also proposed, taking into account constructability and structural reliability. The results provide valuable guidance for the seismic design of composite systems in large-scale structures.

본 연구에서는 고분자 점도 조절제를 첨가하여 졸-겔법 기반 알루미나 나노여과막을 단일 공정으로 제조하고, 코 팅층의 구조 및 성능을 제어하는 방법을 제시하였다. Hydroxypropyl cellulose (HPC, Mw ~80000) 고분자를 알루미나 졸에 첨가하여 점도를 10 mPa·s에서 최대 4200 mPa·s까지 조절하였으며, 이를 통해 알루미나 중공사 지지체 표면에 균일하고 결 함이 없는 선택층을 형성하였다. HPC 함량이 증가할수록 코팅층 두께가 증가하였으나, 기공 크기 증가에 따라 분리 성능이 저하되었다. 2:1 (졸:HPC 고분자 용액) 혼합비에서 제조된 나노여과막은 두께 3.20 μm의 얇은 선택층을 형성하여 높은 수투 과도(12.9 LMH/bar)와 우수한 제거 성능(PPG 1050 Da 제거율 60%, PEG 1500 Da 제거율 90%, MgCl2 제거율 80%)을 나타 냈다. 반면, 1:2 혼합비에서는 선택층 두께가 10.2 μm로 증가하였으나, 기공 크기가 증가하여 3400 Da MWCO와 64% 염 제 거율을 보였다. HPC 고분자를 활용한 점도 제어는 졸-겔 코팅층의 두께, 기공 구조 및 분리 성능을 효과적으로 조절할 수 있 음을 입증하였다.

만성 상처, 특히 다제내성 세균 감염으로 복잡한 상처는 임상적 상처 관리에서 지속적인 도전 과제이다. 자연 유 래 생체 고분자인 키토산은 고유한 항균 활성, 생체 적합성 및 필름 형성 특성으로 주목받고 있다. 그러나 단독 사용은 기계 적 강도가 낮고 약물 보유가 짧기 때문에 제한적이다. 이 총설에서는 은 나노입자(AgNPs), 폴리카프로락톤(polycaprolactone, PCL), 셀룰로오스 나노섬유(cellulose nanofibers, CNF) 및 그래핀 옥사이드(graphene oxide, GO)를 포함하는 시스템을 중심 으로 키토산 기반 복합막의 최근 발전을 살펴본다. 이러한 복합막은 항균 효능, 기계적 내구성 및 조절된 약물 방출을 향상시 켜 막 성능을 향상시킨다. 이러한 다기능 막의 물리화학적 특성, 항균 결과, 세포 적합성 및 치료 잠재력을 비판적으로 평가 하여 차세대 상처 드레싱 개발에 대한 가능성을 강조한다.

This work focuses on the development of an innovative detection platform utilizing a novel ternary composite of transition metal dichalcogenide ruthenium disulfide ( RuS2), tungsten trioxide ( WO3) and multi-walled carbon nanotubes ( RuS2/ WO3/MWCNT) for the purpose of detecting hazardous pollutant catechol. An augmented current response for catechol was acquired by the synergetic effect of ternary composite. The unique combination of these materials enhances the sensor’s electrochemical performance due to the excellent catalytic activity of RuS2, redox properties of WO3 and the high surface area and electrical conductivity provided by MWCNTs. Morphological and structural characterizations were done using different characterization methods. The increased electroactive surface area and fast electron transfer rate resulted by the adaptation of the working electrode leads to the development of a sensitive and selective sensor. The RuS2/ WO3/MWCNT modified electrode exhibited remarkable sensitivity towards catechol determination with a wide linear detection range of 1.0–1028.0 μM and a modest low detection limit of 0.61 μM. The sensor demonstrated consistent performance in assessing the reproducibility and repeatability trials. The fabricated sensor gave reliable results and satisfactory recovery range when application on real-time sample analysis.

All-vanadium redox flow battery (VRFB) has been considered as a promising candidate for the construction of renewable energy storage system. Expanded graphite possesses immense potential for use as typical bipolar plates in VRFB stacks. Nevertheless, the pure expanded graphite bipolar plates suffer from severe swelling in electrolyte, resulting in the losses of mechanical stability and electrical conductivity, thus leading to the efficiency decay within several cycles. Herein, we present a “nanoglue” strategy for tuning the structure/surface properties of expanded graphite by employing polyvinylidene fluoride (PVDF) polymer as structural sealant. Such PVDF “nanoglue” on expanded graphite results in the fine-repairment toward the surface microcracks and cross-section edges, which is beneficial to suppress the electrolyte permeation and improve the anti-swelling capacity. Moreover, it has been found that the PVDF “nanoglue” can improve the flexibility, allowing for the fabrication of ultrathin bipolar plates (0.67 mm) with low electrical resistivity. Benefiting from these integrated characteristics, the VRFB employing the as-fabricated composite bipolar plates delivers excellent cyclic efficiencies (voltage efficiency, coulombic efficiency, and energy efficiency) and ultralow ohmic voltage loss of less than 1.1 mV (< 0.1% of the VRFB rated voltage of 1.25 V) at a high current density of 200 mA cm− 2.

본 연구에서는 온대산재 및 남양재 원목을 표층재로하고, 금속, 유리섬유, 탄소섬유로 보강한 코르크 보드를 중층에 배열한 코르크 복합 원목마루판 의 치수안정성을 평가하였다. 표층재에 따른 코르크 복합 원목마루판의 평균 흡수율은 백합나무(Tu)가 6.1%로 가장 높은 값을 나타내었고, 티크와 멀바우가 4.7%로 가장 낮은 값을 나타내었으며, 밀도가 낮은 온대산재를 배열한 원목마루판보다 남양재에서 낮은 값을 나타내는 것이 확인되었다. 중층보강재는 CM (cork board-metal) 타입이 CG (cork board-glass fiber) 및 CC (cork board-carbon fiber)타입에 비하여 높은 흡수율을 나타내어 밀도에 따른 흡수량의 차이가 확인되었다. 표층 수종에 따른 흡수두께팽창률은 백합나무가 7.2%로 가장 높은 값을, 티크(T)가 3.9%로 가장 낮은 값을 나타내었다. 전반적으로 금속 보강 원목마루판(CM)의 흡수두께팽창률은 유리섬유(CG)와 탄소섬유(CC)에 비하여 금속이 2–3배 높은 값을 나타내었다. 금속 보강 원목마루판을 제외한 모든 원목마루판은 목질 마루판에 관한 KS 규격 기준을 충족하는 우수한 치수안정성을 나타내는 것이 확인되었다.

The use of aluminum-based hybrid metal matrix composite (HMMC) materials, especially in engine components like pistons, is intended to improve wear resistance and overall performance. Crucial tribological indicators, such as wear and friction coefficients, underscore the significance of these materials. However, present aluminum alloys have limited wear because of clustered reinforced particles and relatively high coefficients of thermal expansion (CTE), resulting in inadequate anti-seizure properties during dry sliding conditions. This research introduces a novel “Hybrid Metal Matrix Composite of Al7068 Reinforced with Fly Ash-SiC-Al2O3”. Al7068 is employed for its superior strength-to-weight ratio and specific modulus, which is ideal for components exposed to cyclic loads and varying temperatures. The integration of fly Ash (FA), silicon carbide (SiC), and alumina (Al2O3) as reinforcements enhances wear resistance, diminishes particle clustering, improves stiffness, mitigates CTE discrepancies, and fortifies the composite against strain and corrosion, thereby enhancing its overall performance. The Stir-casting method was used with optimized reinforcement percentages (10 % total), and comprehensive evaluations through wear tests and mechanical property analyses determined the composite's optimal composition. The proposed HMMC variant with the most suitable reinforcement percentage exhibited enhanced engine piston functionality, reduced wear, low deformation of 0.20 mm, and a comparatively higher ultimate tensile strength of 190 megapascals (Mpa).

Transition metal/porous carbon composite is good electrode candidate since porous carbon provides high surface porosity which promotes the access of electrolyte ions, and transition metal enables redox reactions to improve specific capacitance and energy density. In this study, iron/carbon nanofiber (CNF) composite electrodes were prepared by grafting ferrocenecarboxaldehyde to the CNFs which were fabricated by electrospinning and thermal treatment of polyacrylonitrile (PAN). The presence of iron on the CNF surface was confirmed by SEM/EDS, ICP-MS and XPS. Electrochemical performance was evaluated using a three-electrode cell with 1 M Na2SO4 as an electrolyte. Iron-grafted CNFs exhibited a high specific capacitance of 358 F g− 1 and an energy density of 49.7 Wh kg− 1 at 0.5 A g− 1, which is significantly higher than those for untreated CNFs (68 F g− 1 and 9.4 Wh kg− 1). This demonstrates that this iron/CNF composite is promising candidate for supercapacitor electrode with outstanding energy storage performance.

In this study, we developed electrochemical sensors based on the composite of hydroxylated multiwalled carbon nanotubes (MWCNT-OH) and graphene for paraoxon-ethyl detection as pesticide residues in agricultural products. Chemical treatment was employed to produce MWCNT-OH from pristine MWCNT and its composite with graphene was subsequently characterized using FTIR, Raman spectroscopy, FESEM-EDX, TEM, and XPS techniques. The MWCNT-OH/graphene composite was employed as an electrode modifier on the glassy carbon electrode (GCE) surface, and its electroanalytical performances were studied using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. It was revealed the optimum composition ratio between MWCNT-OH and graphene was 2:8, for paraoxon-ethyl detection at pH 7. This could be attributed to the enhanced electrocatalytic activity in the MWCNT-OH/graphene composite which displayed a linear range of paraoxon-ethyl concentration as 0.1–100 μM with a lower detection limit of 10 nM and a good sensitivity of 1.60 μA μM cm− 2. In addition, the proposed sensor shows good reproducibility, stability, and selectivity in the presence of 10 different interfering compounds including other pesticides. Ultimately, this proposed sensor was tested to determine the paraoxon-ethyl concentrations in green apples and cabbage as samples of agricultural products. The obtained concentrations of paraoxon-ethyl from this proposed sensor show no significant difference with standard spectrophotometric techniques suggesting this sensing platform might be further developed as a rapid detection of pesticide residue in agricultural products.

Many recent research efforts have focused on developing high-performance wearable health monitoring systems. This work presents a mechanically stretchable and skin-mountable sensor system based on a conductive polymer composite-based elastic printed circuit board (EPCB) in which a resistive-type composite strain sensor is monolithically integrated. The composite-based EPCB is simply prepared by patterning a silver nanowire (AgNW)/dragon skin (AgNW/DS) composite film in a programmable manner using a direct cut patterning technique. The proposed sensor system was successfully fabricated by directly mounting various components (e.g., microcontroller, circuit elements, light emitting device chips, temperature sensor, Bluetooth module) on the prepared AgNW/DS-based EPCB. The fabricated sensor system was found to be highly stretchable and rollable enough to maintain tight adhesion to the wrist region without significant physical deterioration, even when the wrist was in motion. The wireless sensor system attached to the wrist part enabled us to monitor the wrist motion and surrounding temperature in real time, opening the possible application as a wearable health monitoring platform.

The purpose of this study is to evaluate by experiments and 3-D finite element predictions of strain-hardening cementitious composite(SHCC) structural walls. The specimen of concrete wall used shear reinforcements to satisfy with design shear strength, while the specimen of a SHCC wall used minimum shear reinforcement. The finite element prediction is based on the total strain crack model, and appropriate tensile models were applied according to the material characteristics of concrete and SHCC. The accuracy of the finite element prediction was verified by comparison with experimental results, and the SHCC wall showed superior structural performances in overall load-carrying capacity as well as in reductions of damages caused by crack localizations, even with minimum use of shear reinforcements.

최근 지구온난화로 인한 피해가 심각해짐에 따라 화석연료 사용을 줄이고자 친환경 수소 에너지의 활용이 증가하고 있다. 이에 따라 수소의 저장 및 운송을 위한 수소 저장 용기의 수요가 확대되고 있으나, 현재 널리 사용되고 있는 강재 기반 저장 용기는 부식과 같은 내구성 저하 현상에 취약하다. 따라서 선행 연구는 지지부 부식에 따른 내진 성능 저하 문제를 해결하기 위해 부식 저항성 이 뛰어난 CFRP를 지지부 기둥을 적용하여 설계 하중에서 적용성을 검토하였다. 이때 본 연구는 CFRP의 강도-중량비가 높음을 고려 하여 기존 강재 구조물 지지부 ㄱ 단면 대비 높은 강성을 가진 H 단면과 ㅁ 단면을 지지부 기둥에 적용하여 연구를 수행하였다. 이때 실제와 가까운 해석 결과를 도출하기 위해 고유진동수 추출해석을 진행하여 감쇠 계수를 적용 시켰고, AC 156 인공 지진을 설계 하중 으로 적용한 결과, ㅁ 단면을 적용한 강재 기둥의 접합부 응력은 222.34 MPa로 기존 ㄱ 형강 대비 78.93%로 설계 하중에 만족함을 보였다. ㅁ 단면 적용 CFRP 기둥은 파손 지수(DI)를 통해 평가하였고, 이때 최대 DI는 수지 인장에서 발생하였으며, 그 값은 0.708로 파괴 기준 대비 29.2% 낮아 설계 하중에 만족함을 보였다. 또한, 기초 슬래브에서 쪼갬 인장 응력과 휨 인장 응력을 통한 평가를 진행 하였고, 현장 실험 결과와 마찬가지로 설계 하중에 휨 인장 파괴가 발생하는 것으로 확인하였다. 하지만 파단 시점은 CFRP에서 1.54배 오래 설계 하중에 견디는 것을 확인하여, 그 적용성을 확인하였다. 결론적으로 지진의 발생 빈도가 높아짐에 따라 수소 저장 용기의 안전성 확보가 시급하다. 따라서 기존 강재 대상 구조물의 부식으로 인한 강성 저하 문제를 해결하기 위해, 높은 내구성 및 부식 저항성 재료의 적용은 필수적이다. 동시에 기초 슬래브의 안전성 확보에 대한 연구가 추가적으로 수행되어야 한다.