This study examines the developmental trajectory of feedback research in Korean EFL writing from the early 1990s to 2025 through a qualitative systematic synthesis of KCIindexed journal articles. Drawing on major learning theories and educational reforms, the study identifies four stages that reflect shifts in curriculum policy, assessment practices, and the gradual incorporation of digital and AI-based tools. Early work was characterized by teacher-centered and form-focused corrective feedback, followed by comparative studies of feedback types influenced by sociocultural theory and formative assessment perspectives. Recent research has increasingly addressed learners’ metacognition, self-regulation, feedback uptake, and AI-mediated practices. Despite these broader theoretical orientations, the literature remains dominated by short-term interventions and perception-based studies, with limited evidence on sustained writing development in classroom settings. The findings indicate a gap between theoretical advancement and instructional practice in Korean EFL writing. This study calls for longitudinal, classroom-based, and mixed-method research that examines how teacher-, peer-, and AI-mediated feedback can be integrated within context-sensitive instructional models.

Poor bonding occurs with resin due to surface inertness of carbon fiber (CF), so CF surfaces were often treated. In some common surface treatments, sizing was a simple and effective modification method. Polyurethane (PU) was used as the main component of sizing agents due to its similar structure to polyamide 6 (PA6). The CF/PA6 composites’ interfacial properties were improved using PU as a sizing agent. Meanwhile, in this paper, glycidol (GLD) was introduced into the PU emulsion so that the epoxy group reacted with the carboxyl group on the acidified CF. After testing, when the content of glycidyl in the sizing agent is 2%, the CF/PA6 composites showed an important improvement in tensile, impact, and flexural strengths, which increased by 49.4%, 94.6%, and 53.2%, respectively. In addition, the effect of modified WPU sizing agents with different GLD contents on the properties of CF/PA6 composites was investigated.

In this study, C.I. Pigment Blue 15:3, an organic phthalocyanine based pigment, was used as a precursor to synthesize activated carbon/copper/copper oxide composite through a carbonization and activation process. The resulting composite was investigated to evaluate the potential use as a hybrid capacitor electrode of supercapacitor and pseudo-capacitor. Precursor was pre-treated at 600 °C, followed by activation at 750 °C using alkaline activating agents (KOH and K2CO3). Neutral ZnCl2 activating agent was also used for activation at 700 °C without pre-treatment to compare the electrochemical performance. The KOH activated sample exhibited the presence of Cu, CuO, and Cu2O in XRD and XPS analysis results and it also showed a highest specific surface area of 2731 m2/ g and well-developed 0.7–2.0 nm micropores, enhancing ion adsorption in K2SO4 electrolyte. Electrochemical tests revealed that PB_KOH exhibited the highest capacitance, outperforming commercial Norit Carbon at various current densities, due to its Cu/CuO/Cu2O/activated carbon composite structure. These findings highlight its strong potential as a high-performance supercapacitor electrode material.

This paper reviews MAX phases (bulk) and their 2D derivative, MXenes, focusing on synthesis methods, properties, and applications. Traditional and advanced synthesis techniques, including solid-state synthesis and spark plasma sintering, are examined, emphasizing structural diversity. Key characteristics, such as thermal stability, electrical conductivity, and mechanical resilience, are explored alongside their mechanisms. The review also highlights advancements in energy harvesting applications, such as H 2 production, solar cells, energy storage, catalysis, spintronics, electronic devices, and environmental remediation. Additionally, future research directions are outlined to address existing gaps and enhance their role in next-generation technologies and environmental remediation.

We demonstrate a carbonate-suppressed hydrothermal route for synthesizing tetragonal BaTiO3 (BT) nanoparticles using barium acetate as the Ba source. Commercial TiO2 (P25) was converted to BT in KOH at 240 °C for 6 h without post-annealing. Relative to conventional Ba(OH)2 routes, the acetate precursor markedly reduced BaCO3 formation and narrowed the particle-size distribution. Systematic tuning of the Ba/Ti ratio (≥ 1.3) further optimized nucleation and growth, yielding uniform ~100 nm particles at Ba/Ti = 1.7 with the highest tetragonality (c/a ≈ 1.0076), as verified by XRD (002/200 splitting) and corroborated by Raman signatures of the tetragonal phase. Trace carbonate, when present, could be removed by mild weak-acid washing (e.g., acetic or citric acid) as effectively as with strong acids, but with improved process safety and practicality. The combined use of barium acetate, controlled Ba/Ti chemistry, and gentle carbonate removal yields phase-pure, highly tetragonal BT nanoparticles from low-cost precursors in a short dwell time, offering a scalable pathway to MLCC-grade powders.

The medicinal fungus Cordyceps militaris is recognized for producing cordycepin, a bioactive nucleoside with anticancer, immunomodulatory, and antioxidant properties. However, conventional culture media often entail high production costs and limited sustainability, prompting the search for alternative nutrient sources. This study evaluated onion, green onion, and garlic peel extracts—agricultural by-products rich in flavonoids, phenolics, and sulfur-containing antioxidants—as sustainable substrates for enhancing mycelial biomass and cordycepin biosynthesis in C. militaris. Liquid cultures supplemented with peel extracts (1–5%) were assessed for growth, cordycepin production (HPLC), and antioxidant activity (DPPH assay). Onion peel extract (OPE) showed the strongest growth-promoting effect, yielding 8.2 g/L of biomass at 5% and achieving a 19% increase in cordycepin concentration at 3% compared with the control. Antioxidant activity strongly correlated with cordycepin accumulation (R = 0.96, p < 0.001), indicating that secondary metabolite production contributed significantly to radicalscavenging capacity. Response surface methodology using a Box–Behnken design revealed that extract concentration, pH, and incubation period significantly influenced cordycepin production (p < 0.05), with the quadratic model showing excellent fit (R² = 0.9924). Optimal conditions were identified as 3% extract concentration, pH 6.0, and 12 days of incubation, under which cordycepin reached 0.995 mg/L, substantially higher than the control (0.693 mg/L). These findings demonstrate that agricultural by-product extracts, particularly onion peel, can serve as effective and economical substrates for enhancing cordycepin biosynthesis while supporting sustainable bioprocessing strategies in C. militaris cultivation.

Ultra-high temperature ceramics (UHTCs) exhibit extremely high melting points (> 2,500 °C) and maintain structural stability under severe conditions. However, their intrinsic brittleness and oxidation vulnerability limit their direct application in aerospace components exposed to extreme environments. To overcome these limitations, UHTC-based composites reinforced with secondary phases such as ZrO2 are required to improve fracture toughness and oxidation resistance. The polymer infiltration and pyrolysis (PIP) process provides a promising fabrication route for such composites, offering densification of porous matrices with liquid precursors while maintaining uniform microstructures. Here, we report a novel zirconia precursor (PZC-12) synthesized through a sol-gel reaction of zirconium propoxide with acrylic acid (1:2 molar ratio). The liquid precursor exhibited a suitable viscosity (~518 cP) and enabled dual crosslinking via hydroxyl condensation combined with radical polymerization of vinyl groups. Consequently, effective thermal curing was accomplished upon heating at 80 °C for 12 h. This strategy minimized premature decomposition and achieved a high ceramic yield of 52.7 %. Pyrolysis at 600 °C in air produced nanosized t-ZrO2, which transformed into m-ZrO2 with grain growth at higher temperatures. Applied in PIP, a ZrB2-ZrO2 composite was successfully fabricated, demonstrating that dual crosslinking is critical for high-yield, reliable PIP-based UHTC composites.

This study presents the synthesis of molybdenum disulfide (MoS₂) using flashlamp annealing and provides a comprehensive investigation of its structural and physical properties. The proposed flash-induced approach enables rapid production of high-quality MoS₂, offering superior process efficiency compared to conventional synthesis techniques. The structural, electronic, and thermal characteristics of the synthesized MoS₂ were systematically examined using multiple analytical methods, with particular attention to how synthesis conditions influence layer structure, crystallinity, and defect density. The results indicate that MoS₂ produced through this method exhibits material properties suitable for high-performance electronic devices and energy storage applications. Moreover, this work demonstrates the potential of flash-induced synthesis for scalable and practical fabrication of MoS₂-based nanomaterials, thereby contributing to the broader advancement of transition metal dichalcogenide technologies across diverse nanotechnology applications.

전기화학적 탄소 포집은 에너지 집약적인 열역학적 공정에 대한 유망한 대안으로, 등온 운전 및 재생 에너지원과 의 통합을 가능하게 한다. 그러나 주로 드롭 캐스팅 기술에 의존하는 현재의 전극 제조 방식은 확장성을 제한하고 활물질과 전도성 물질 사이의 불균일한 계면으로 인해 전도 경로의 효율을 저해한다. 본 연구에서는 확장 가능한 전기화학적 탄소 포집 응용 분야를 위해 전기화학적 CO2 반응 특성을 가짐과 동시에 용액 공정이 가능하고 산화-환원 활성을 가지는 폴리이미드 (redox-active polyimides, RAP)의 첫 번째 사례를 보고한다. 합성된 RAP는 N-메틸-2-피롤리돈(N-methyl-2-pyrrolidone, NMP) 및 N,N-디메틸포름아미드(N,N-dimethylformamide, DMF)와 같은 유기 용매에서 우수한 용액 가공성을 보였으며, 용해도는 산화-환원 활성 유닛을 가지는 단량체의 조성에 따라 달랐다. 질소 및 이산화탄소 포화 조건에서 수행된 순환 전압전류법 실 험을 통해 CO2 대기 조건에서 반파 전위의 뚜렷한 변화를 관찰하였으며, 이는 RAP의 CO2 분자와의 반응성을 입증해주는 결 과이다. 용액 가공성, 산화-환원 활성, CO2 반응성의 조합은 RAP를 대규모 전기화학적 탄소 포집 시스템에서 활용 가능한 유 망한 후보로 자리매김하여 효과적인 CO2 제거 성능을 유지하면서 전극 호환성과 제조 확장성 측면에서 중요한 과제를 해결 할 수 있다.

Bisphenol F (BPF) is a substitute agent for bisphenol A and is widely used in the production of materials such as epoxy resins and plastics. BPF accumulates in surface water because of its nonbiodegradable and recalcitrant nature, making it difficult to remove. In this study, the removal of BPF through a photocatalytic process was evaluated using zinc oxide (ZnO)/reduced graphene oxide (RGO) microspheres. A spray drying method was used to prepare the ZnO/RGO microspheres, which combine the photocatalytic efficiency of ZnO with the high electron mobility and large surface area of RGO, achieving a bandgap of 2.53 eV. Structural and morphological analyses confirmed the successful hybridization of the ZnO/RGO microsphere composite. The photocatalytic activity of the ZnO/RGO microspheres was evaluated under various light sources, with the highest degradation efficiency achieved under ultraviolet C irradiation. The optimal catalyst dosage of the ZnO/RGO microspheres was determined to be 0.1 g/L for BPF removal (BPF initial concentration = 5 mg/L). Scavenger tests revealed the dominance of superoxide radicals ( O2 ·−) in the degradation process. The effects of pH (3.52–9.59), ions ( Cl−, NO3 −, and SO4 2−), and natural organic matter were also examined to assess the practical applicability of the ZnO/RGO microsphere photocatalytic system. High pH levels and the presence of NO3 − (> 10 mM) were found to enhance BPF removal. This research highlights the potential of the ZnO/RGO microspheres as efficient photocatalysts for the removal of BPF in aqueous solutions.

Carbon nanotube (CNT) has promising applications in several fields due to their excellent thermal, electrical, mechanical, and biocompatible properties. However, the complexity of its structure leads to the problems of computationally intensive and inefficient synthetic characterization optimization and prediction by traditional research methods, which seriously restricts the development process. Machine learning (ML), as an emerging technology, has been widely used in CNT research due to its ability to reduce computational cost, shorten the development cycle, and improve the accuracy. ML not only optimizes the synthetic control parameters for precise structural control, but also combines various imaging and spectroscopic techniques to significantly improve the accuracy and efficiency of characterization. In addition, ML helps to improve the performance of CNT devices at the optimization and prediction levels, and achieve accurate performance prediction. However, ML in CNT research still faces challenges such as algorithmic processing of complex data situations, insufficient space for algorithmic combined optimization, and lack of model interpretability. Future research can focus on developing more efficient ML algorithms and unified standardized databases, exploring the deep integration of different algorithms, further improving the performance of ML in CNT research, and promoting its application in more fields.

Single-walled carbon nanotubes (SWCNTs) are a promising material for advancing the field of materials. However, controlling the controlled growth of SWCNTs by conventional chemical vapor deposition or other growth processes remains challenging. Recent studies have shown that some progress has been made in the synthesis mechanism, catalysts and growth processes of SWCNTs, which makes the controlled growth of SWCNTs possible. This paper reviews the common SWCNTs, the synthesis process, and the applications. The paper firstly discusses the differences in the structure and properties of different types of SWCNTs and the related studies on these properties. Next, the paper discusses the mechanisms, catalysts, and growth processes used to synthesize SWCNTs, from experimental characterization to simulation analysis. Subsequently, the paper describes some applications of SWCNTs in popular fields such as functionalization, transistors, electrochemistry, and so on. Finally, a brief outlook on the challenges and future development of these SWCNTs in the research field is presented.

In this study, quantum dots with Au/CdSe complex cores composed of Au as a metal base were synthesized, syrup was prepared, and coated on natural simulated LED unit modules, and the optical properties of traffic signs using them were investigated, and the following conclusions were obtained. The nanoparticles synthesized at 260°C and 280°C grew into irregular shapes with PL wavelengths of 624-627㎛, half-widths of 35㎛, PL-QY ratios of 55-61%, and grain diameters of 5-7㎛. The quantum dot syrup was applied to the LED unit module to produce a traffic sign composed of 4CL unit modules, and the luminance of 179 ㏅/㎡, insulation resistance of 10,000㏁, and insulation withstand of 500V were achieved, meeting the performance and specifications of the standard guidelines for luminescent traffic safety signs. The surface temperature of the unit module laminated with 4CL resin is 24~25℃, which shows a stable heat distribution, confirming that it can be applied as a sign using unit modules.

513 magnesium hydroxide sulfate hydrate (MHSH) and Mg(OH)₂ were synthesized by controlling the pH and concentration using a domestic resource, dolomite (CaMg(CO3)2), as the raw material. The MgSO₄ was extracted by treating dolomite with sulfuric acid under various conditions. Hexagonal plate-shaped Mg(OH)₂ and needle-like 513 MHSH were synthesized under the hydrothermal condition. The morphology of the synthesized materials was controlled by adjusting the pH (SO42-/OH- ratio) and hydrothermal reaction time. As the pH of the solution increased, the formation of plate-like structures became dominant, whereas lower pH values (higher SO42- concentration) led to needle-like forms. The results of the 513 MHSH, which was synthesized using reagents and sea bittern, are consistent with the synthesis conditions, and we observed changes in the length and aspect ratio of the needle-shaped structure in response to adjusting the hydrothermal reaction time.

부피가 큰 테트라페닐보레이트를 대응 음이온으로 갖는 이온성 공액구조 고분자 전해질을 소듐 테트라페닐 보레이트를 이용한 폴리(2-에티닐-N-퍼플루오로헥실피리디늄 아이오다이드)의 이온교환반응을 통해 합성하였다. 여 러 가지 분석장비를 사용하여 고분자 구조를 분석한 결과, 합성한 고분자는 N-퍼플루오로헥실피리디늄 테트라페닐 보레이트 치환기를 갖는 폴리아세틸렌 주쇄 구조임을 알 수 있었다. 폴리(2-에티닐-N-플로로헥실피리디늄 테트라페 닐보레이트)의 전기-광학적 및 전기화학적 특성을 측정하고 분석하였다. 고분자의 흡수 스펙트럼에서 최대 흡수 피 크는 330nm와 466nm에서 관찰되었다. 전기화학적 특성 시험의 50 주기의 연속 스캔 실험을 통하여 본 고분자의 산화 및 환원 안정성을 확인하였다. 이 고분자는 도핑과 탈도핑 피크 사이에서 비가역적인 전기화학 거동을 보였 으며 동역학적 확산 거동을 보였다.

염화동 에칭 공정에서 발생한 철염 폐수를 전구체로 활용하여 마그네타이트(Fe3O4)를 합성하고, 이를 인산염 흡착 및 회수에 적용하였다. 합성 조건 최적화를 위하여 Box–Behnken Design를 적용한 반응표면분석법(Response Surface Methodology, RSM)을 활용하여 회귀모델을 구축하였다. 모델을 통해서 도출한 최적 합성 조건은 Fe3+/Fe2+ 비율 1.7, NaOH 농도 0.7 N, 숙성 시간 86.3분으로 확인되었다. 해당 조건에서 합성된 마그네타이트는 10.9 mg-P g-1 마그네타이트의 인산염 흡착 용량을 나타내었다. 기기 분석 결과, 최적화된 마그네타이트는 고순도 결정 구조와 초상자성 특성을 나타냈으며, 비표면적과 반응성이 향상된 것이 확인되었다. 또한 연속 회분식 반응조(Sequencing Batch Reactor, SBR)에 적용한 결과, 5회 반복 흡착–탈착 동안 평균 인산염 회수율은 46.6%로 나타났다. 유입 인산염 농도가 200 mg-P L-1의 고농도 조건에서도 회수율이 안정적으로 유지되어, 마그네타이트가 인산염 흡착제로서의 활용 가능성과 안정성을 입증하였다.