The Public Procurement Service was established to ensure efficient supply of necessary goods for public institutions and their quality stability. The Public Procurement Service operates the Excellent Product Designation System for quality improvement. Due to the convenience of sole-source contracts and pricing advantages, suppliers prefer to obtain excellent product certification. However, despite these advantages, the designation does not guarantee customer satisfaction, as consumers pay higher prices without assured quality improvements. The goal of this study is to propose a new evaluation system better reflecting customer satisfaction and repurchase intention. Metal window products were selected as the study subject. Candidate factors were derived through literature review, and surveys were conducted to identify significant items for the new evaluation system. Item weights were then calculated using AHP analysis. The proposed system was validated through case analysis comparing two excellent products with two general products.

It is addressed that the challenges of poor cyclic stability and low conductivity in metal–organic frameworks (MOFs) hinder their application in energy storage. Here, we synthesized binary metal MOFs through a one-step hydrothermal process, subsequently calcined to produce Co–Mn/reduced graphene oxide (rGO). This approach not only carbonized the organic framework but also enhanced its electrical conductivity and stability. Our findings demonstrated that the synergistic effects of Co and Mn within the assembled electrode resulted in remarkable performance, achieving a specific capacitance of 3558.65 F g− 1 at 1 A g− 1 and a rate capability of 1000 F g− 1 at 30 A g− 1. The Co–Mn/rGO anode in the asymmetric supercapattery exhibited a broadened operating potential window of 1.5 V, delivering an energy density of 54.65 W h kg− 1 at a power density of 125 W kg− 1, and maintaining 11.375 W h kg− 1 at a high power density of 12,500 W kg− 1. Notably, the capacitance retention rate reached 99.99% after 10,000 cycles at a current density of 10 A g− 1. These results suggest that the developed Co–Mn/rGO composite represents a promising candidate for advanced energy storage systems, offering both high performance and stability.

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).

This study incorporates the formation of carbon quantum dots (CQDs) via a hydrothermal approach, recording the first-time use of castor leaves as a natural precursor. The used precursor offers various benefits including novelty, abundance, elemental composition, and biocompatibility. CQDs were further characterized with multiple techniques including high-resolution transmission electron microscope (HR-TEM), X-ray photoelectron microscopy (XPS), X-ray diffraction (XRD), Fouriertransform infrared spectroscopy (FTIR), Raman spectroscopy, UV–visible spectroscopy, Zeta analysis, and optical spectroscopy. They are fundamentally composed of carbon (71.37%), nitrogen (3.91%), and oxygen (24.73%) and are nearly spherical, and uniformly distributed with an average diameter of 2.7 nm. They possess numerous interesting characteristics like broad excitation/emission bands, excitation-sensitive emission, marvelous photostability, reactivity, thermo-sensitivity, etc. A temperature sensor (thermal sensitivity of 0.58% C− 1) with repeatability and reversibility of results is also demonstrated. Additionally, they were found selective and sensitive to ions in aqueous solutions. So, they are also utilized as a fluorescent probe for metal ion ( Fe3+) sensing. The lowest limit of detection (LOD) value for the current metal ion sensor is 19.1 μM/L.

As the demand for sustainable hydrogen (H₂) production grows, catalytic decomposition of methane (CDM) has emerged as a CO2- free pathway for H2 generation, producing valuable multi-walled carbon nanotubes (MWCNTs) as byproducts. This study examines the role of fuel type in shaping the properties and performance of NiOx/AlOx catalysts synthesized via solution combustion synthesis (SCS). Catalysts prepared with citric acid, urea, hexamethylenetetramine (HMTA), and glycine exhibited varying NiO nanoparticle (NP) sizes and dispersions. Among them, the HMTA catalyst achieved the highest Ni dispersion (~ 3.2%) and specific surface area (21.6 m2/ gcat), attributed to vigorous combustion facilitated by its high pH and amino-group-based fuel. Catalytic tests showed comparable activation energy (55.7–59.7 kJ/mol) across all catalysts, indicating similar active site formation mechanisms. However, the HMTA catalyst demonstrated superior CH4 conversion (~ 68%) and stability, maintaining performance for over 160 min under undiluted CH₄, while others deactivated rapidly. MWCNT characterization revealed consistent structural properties, such as graphitization degree and electrical conductivity, across all catalysts, emphasizing that fuel type influenced stability rather than MWCNT quality. H2 temperature-programmed reduction ( H2-TPR) analysis identified moderate metal-support interaction (MSI) in the HMTA catalyst as a key factor for optimizing stability and active site utilization. These findings underscore the importance of fuel selection in SCS to control MSIs and dispersion, offering a strategy to enhance catalytic performance in CDM and other thermocatalytic applications.

Biochar is considered as key anode material for alkali metal (lithium, sodium, and potassium) ion batteries (AIBs) owing to its rich microstructural features, high specific surface area, active sites, excellent conductivity, and mechanical strength. The multidimensional structures and diverse functional groups of biochar make it enable easy modification to improve ion transport, interface deposition behavior, and electrolyte stability. In addition, biochar-based derivatives, such as silicon/biochar composite anode materials, combine the advantages of high-energy density and low lithiation potential of silicon materials, as well as the superior conductive ability and outstanding mechanical qualities of biochar. In this review, the microstructure, properties, and synthesis methods of biochar materials are systematically clarified, and then, their applications in AIBs are presented followed by summarizing the energy storage mechanism and advanced physicochemical characterizations. Common structural configurations and preparative technique for biochar/silicon-based composites are summarized, such as core–shell, yolk–shell, and embedded coating structures with improved electrochemical and mechanical stability. Finally, toward practical application of biochar and biochar-based derivatives in future AIBs, the issues and challenges are outlined.

In recent years, there has been growing interest in the potential applications of carbon-based non-metallic catalysts in various fields, such as electrochemical energy storage, electrocatalysis, thermal catalysis, and photocatalysis, owing to their unique physical and chemical properties. Modifying carbon catalyst surfaces or incorporating non-metallic heteroatoms, such as nitrogen (N), phosphorus (P), boron (B), and sulfur (S), into the carbon structure has emerged as a promising approach to improve the catalytic performance. This method enables the adjustment of the electronic structure of the carbon catalyst's surface, leading to the formation of new active sites or the reduction of side reactions, ultimately enhancing the catalyst's performance. Here, the preparation methods for doped non-metallic heteroatom carbon catalysts have been systematically explored, encompassing techniques, such as impregnation, pyrolysis, chemical vapor deposition (CVD), and templating. Finally, the existing challenges in the application of non-metallic atomic catalysts have been discussed, insights into potential future development opportunities and new preparation methods of carbon catalysts in the future have been offered.

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.

This study analyzed the methods and characteristics of hydrogen production, storage, transportation, charging, and use of hydrogen presented as an energy supply and demand system for hydrogen. Hydrogen produced by reforming hydrogen, which exists in the form of compounds, is essential to use metal materials exposed to the hydrogen atmosphere in storage and transportation. The mechanism of hydrogen embrittlement and damage cases, which are phenomena in which hydrogen atoms penetrate into the crystal lattice of metal and cause crack failure, were investigated. In addition, it is intended to present a research direction related to the evaluation of physical properties such as thermal conductivity, thermal expansion coefficient, and heat capacity, which are the criteria for selecting materials for hydrogen in a cryogenic environment.

Food contamination with heavy-metal ions and nitrites poses a serious threat to human health. Consequently, the development of fast and sensitive platforms for detecting these contaminants is urgently needed. In this study, a novel sensing platform was developed by integrating carbon nanotubes generated by the pyrolysis of waste masks (WMCNTs) with ZIF-8 for the simultaneous detection of Cd2+, Pb2+, and nitrite. Specifically, the electronic structure of the WMCNT backbone was modulated by doping with B and N atoms. Nanoporous ZIF-8 was then grown in-situ on its surface to produce composites with enhanced electrical conductivities and large specific surface areas. This modification provided more active sites for the attachment of heavy-metal ions and nitrites. Under optimized conditions, the sensing platform exhibited a wide linear range with the Pb2+, Cd2+, and NO2 − limits of detection of 2.68, 12.12, and 5.94 μM, respectively. Notably, the sensing platform demonstrated excellent anti-interference capabilities and effectively detected nitrites and heavy-metal ions in pickled foods.