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).

본 연구는 프로판탈수소(PDH) 공정의 배가스내에 포함되어 있는 탄화수소(HC)를 이용하여 질 소산화물(NOx)을 저감하는 Metal Corrugated HC-SCR 촉매 개발을 목적으로 하였다. 산성도(Si/Al 비) 가 다른 제올라이트계 Chabazite 3종을 Metal Corrugated에 워시코팅하였고, 가장 우수한 NOx 저감 성 능을 나타낸 Chabazite에 구리 함량을 1.5%, 3.0%, 4.5%, 6.0%로 함침하여 촉매를 제조하였다. 제조된 촉 매의 NOx 저감 성능은 실험실 규모의 마이크로 상압반응기상에서 측정하였으며, 촉매 특성분석은 BET, XRF, ICP를 이용하여 분석하였다. 측정 결과, 산성도가 가장 낮은 A-Chabazite가 가장 높은 NOx 저감 성능을 보였고, 구리 함량이 높을수록 Total NOx 저감 성능은 증가되었지만 NO2 저감 성능은 감소되는 것으로 확인되었다. 3.0-A-CHA 촉매는 NO2가 완전 저감되었고, Total NOx 저감에도 큰 효과를 나타내 상용 PDH 공정에서 NO2를 중점적으로 저감하고자 한다면 충분히 적용 가능할 것으로 보인다.

Lithium (Li) metal is a promising anode for next-generation batteries due to its high capacity, low redox potential, and low density. However, dendrite growth and interfacial instability limit its use. In this study, an artificial solid electrolyte interphase layer of LiF and Li-Sn (LiF@Li-Sn) was fabricated by spray-coating SnF2 onto Li. The LiF@Li-Sn anode exhibited improved air stability and electrochemical performance. Electrochemical impedance spectroscopy indicated a charge transfer resistance of 25.2 Ω after the first cycle. In symmetric cells, it maintained a low overpotential of 27 mV after 250 cycles at 2 mA/cm2, outperforming bare Li. In situ microscopy confirmed dendrite suppression during plating. Full cells with NMC622 cathodes and LiF@Li-Sn anodes delivered 130.8 mAh/g with 79.4% retention after 300 cycles at 1 C and 98.8% coulombic efficiency. This coating effectively stabilized the interface and suppressed dendrites, with promising implications for practical lithium metal batteries.

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 습도센서에서 Zn-MOF (금속-유기구조)의 개발과 응용에 대해 다루며, 친환경적 합성과 우수한 전기적 특성을 보고한다. 그린 화학의 원리를 이용하여 제작된 Zn-MOF를 유연한 폴리에 틸렌테레프탈레이트 기판 상에 형성된 깍지낀 구조의 전극과 통합하였다. 상대습도가 10%부터 90%까지 증가할 때, 전기적 특성은 42.49 pF에서 370 nF까지 정전용량의 급격한 상승(약 939,322%)을 나타냈다. 또한, 임피던스는 47 MΩ에서 0.072 MΩ까지 약 99.81% 감소하였다. 제작된 습도센서는 반응시간 5초, 복구시간 약 0.7에서 0.9초로 동적으로 반응하였다. 이러한 결과는 Zn-MOF가 고도로 민감하고 반응성이 뛰어난 습도 모니터링할 수 있는 가능성과, 특히 다양한 환경 조건에서 센서의 정전용량성 반응성을 강조 하고자 한다.

Zinc tin oxide (ZTO) thin films were deposited using atomic layer deposition (ALD) to ensure precise thickness control and uniformity. However, the low-temperature processing of ZTO often results in increased defect states, leading to degraded electrical performance. To address this issue, metal capping layers (Al or Au) were added to the ZTO active layer. The capping layers modulate electron energy levels at the interface, increase carrier density, and reduce interface traps, thereby improving electrical properties. Aluminum (Al) and gold (Au) were evaluated for their impact on key performance metrics, including electron mobility (μsat), threshold voltage (VT), subthreshold swing (SS), and on/off current ratio (ION/OFF). Results show that Al-capped ZTO thin-film transistors (TFTs) exhibited enhanced performance due to the lower work function of Al (4.0 eV), which facilitates electron injection and reduces contact resistance. In contrast, Au-capped ZTO TFTs showed decreased performance due to electron depletion caused by the higher work function of Au (5.1 eV). Optical analyses, including UPS and UV-Vis, revealed the band structure and work function of the ZTO thin films. This study concludes that the choice of capping material and its design parameters play a critical role in optimizing TFT performance, offering valuable insights for the development of next-generation high performance TFT devices.

본 연구는 기능성 화장품 소재 개발을 목표로 효모 유래 MPC의 세포 생리활성을 조사하였 다. 피부 세포주에 처리된 Cu와 Zn 이온 모두 세포 독성이 확인되었지만, 정제된 MPC는 결합된 금속 이온의 세포 독성을 획기적으로 제거하였다. 게다가 특정 농도의 MPC는 대조군과 비교하여 세포 생존 율을 오히려 약 20% 증가시켰다. MPC 중 효모 펩타이드-Cu(YP-Cu)는 UVB 자극으로 유도되는 세포 내 활성산소의 양을 약 30% 정도 유의하게 감소시켰지만, YP-Zn은 영향을 미치지 못했다. 또한, YP-Cu 처리는 피부 세포에서 콜라겐 유전자의 발현량을 2배 증가시켰고, 프로콜라겐 분비량은 1.7배 증 가시켰으며, UVB 자극에 의한 콜라겐 유전자의 발현 저해에도 효과적으로 대응했다. 결론적으로, 유리 금속 이온 자체는 세포독성 효과로 인해 화장품 소재에 적합하지 않지만, 정제된 MPC, 특히 YP-Cu는 이러한 금속 이온의 독성을 효과적으로 상쇄하고 세포 생존율을 향상시킬 뿐만 아니라, UVB 자극에 따 른 유해 효과를 완화하기 때문에 잠재적 기능성 화장품 소재로 사용될 수 있다.

Crystalline heptazine carbon nitride (HCN) is an ideal photocatalyst for photocatalytic ammonia synthesis. However, the limited response to visible light has hindered its further development. As a noble metal, Au nanoparticles (NPs) can enhance the light absorption capability of photocatalysts by the surface plasmon resonance (SPR) effect. Therefore, a series of Au NPs-loaded crystalline carbon nitride materials (AH) were prepared for photocatalytic nitrogen fixation. The results showed that the AH displayed significantly improved light absorption and decreased recombination rate of photo-generated carriers owing to the introduction of Au NPs. The optimal 2AH (loaded with 2 wt% Au) sample demonstrated the best photocatalytic performance for ammonia production with a yield of 70.3 μmol g− 1 h− 1, which outperformed that of HCN. This can be attributed to the SPR effect of Au NPs and alkali metal of HCN structure. These findings provide a theoretical basis for studying noble metal-enhanced photocatalytic activity for nitrogen fixation and offer new insights into advances in efficient photocatalysts.

In recent years, the search on fabrication of highly efficient, stable, and cost-effective alternative to Pt for the hydrogen evolution reaction (HER) has led to the development of new catalysts. In this study, we investigated the electrocatalytic HER activity of the Toray carbon substrate by creating defect sites in its graphitic layer through ultrasonication and anodization process. A series of Toray carbon substrates with active sites are prepared by modifying its surface through ultrasonication, anodization, and ultrasonication followed by anodization procedures at different time periods. The anodization process significantly enhances the surface wettability, consequently resulting in a substantial increase in proton flux at the reaction sites. As an implication, the overpotential for HER is notably reduced for the Toray carbon (TC-3U-10A), subjected to 3 min of ultrasonification followed by 10 min of anodization, which exhibits a significantly lower Tafel slope value of 60 mV/dec. Furthermore, the reactivity of the anodized surface for HER is significantly elevated, especially at higher concentrations of sulfuric acid, owing to the enhanced wettability of the substrate. The lowest Tafel slope value recorded in this study stands at 60 mV/dec underscoring the substantial improvements achieved in catalytic efficiency of the defect-rich carbon materials. These findings hold promise for the advancement of electrocatalytic applications of carbon materials and may have significant implications for various technological and industrial processes.

Carbon quantum dots (CQDs) are novel nanocarbon materials and widely used nanoparticles. They have gradually gained popularity in various fields due to their abundance, inexpensive cost, small size, ease of engineering, and distinct properties. To determine the antibacterial activity of metal-doped CQDs (metal-CQDs) containing Fe, Zn, Mn, Ni, and Co, we chose Staphylococcus aureus as a representative Gram-positive strain and Escherichia coli as a representative Gram-negative bacterial strain. Paper disc diffusion tests were conducted for the qualitative results, and a cell growth curve was drawn for quantitative results. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and IC50 were measured from cell growth curves. As a result, all of the metal-CQDs showed toxicity against both Gram-positive and Gram-negative bacteria. Furthermore, Gram-negative bacteria was vulnerable to metal-CQDs than Gram-positive bacteria. The toxicity differed concerning the type of metal-CQDs; Mn-CQDs exhibited the highest efficacy. Hence, this study suggested that CQDs can be used as new nanoparticles for antibiotics.