• Research Paper

    Surface Modified PCL/PLGA Scaffold Using Binary Drug-Incorporated Calcium Phosphate for Bone Regeneration
    Seunghwan Choy
    We prepared porous poly(ε-caprolactone)/poly(lactic-co-glycolic acid) (PCL/PLGA) 3D scaffolds with surfaces that were modified through the co-precipitation of calcium phosphate (CAP) with binary … + READ MORE
    We prepared porous poly(ε-caprolactone)/poly(lactic-co-glycolic acid) (PCL/PLGA) 3D scaffolds with surfaces that were modified through the co-precipitation of calcium phosphate (CAP) with binary drug components, including risedronate (RSD) and hyaluronic acid (HyA). The 3D porous biodegradable PCL/PLGA scaffolds were fabricated by sintering microspheres prepared with a 30/70 PCL/PLGA blend. The co-precipitation of the CAP coating with binary drug components significantly enhanced the proliferation and differentiation of rat mesenchymal stem cells (rMSCs) on the scaffolds. Although the presence of both HyA and RSD positively improved proliferation and differentiation, HyA and RSD were more effective on osteoblastic proliferation and differentiation, respectively. These results strongly demonstrate that the drug effects on osteoblastic responses were closely interconnected. The two drugs affect rMSCs behavior in a concentration-dependent manner, requiring a balance between proliferation and differentiation for optimal bone regeneration. We expect this surface modification technique could potentially be utilized for the fabrication of functionalized biodegradable scaffolds and delivery of drug mixtures. - COLLAPSE
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    27 January 2025

  • Research Paper

    Synthesis of Bimetallic Cu-Au Nanotubes and Cu@Au Core-Shell Nanowires for Anti-Oxidative Electrodes
    Seokhwan Kim, Geumseong Lee, Chanyeong Lee, Gyeongbok Yang, Seonhwa Park, Yuho Min
    We report the synthesis of bimetallic Cu-Au nanotubes (NTs) and Cu@Au core-shell nanowires (NWs) for use as anti-oxidative electrodes. The fabrication involved … + READ MORE
    We report the synthesis of bimetallic Cu-Au nanotubes (NTs) and Cu@Au core-shell nanowires (NWs) for use as anti-oxidative electrodes. The fabrication involved two key approaches: galvanic replacement to produce Cu-Au NTs and the physical deposition of Au to form Cu@Au core-shell NWs. The galvanic replacement process generated hollow NTs through the Kirkendall effect, driven by the unequal diffusion rates of Cu and Au during the redox reaction. In contrast, the physical deposition of Au, facilitated by fast reduction kinetics using L-ascorbic acid, enabled the formation of a Au shell encapsulating the Cu NWs, preserving their structural integrity. Morphological and structural analyses confirmed the successful formation of both nanostructures. While the Cu-Au NTs exhibited hollow interiors and increased dimensions, the Cu@Au NWs displayed a solid core-shell morphology with minimal diameter increase. Electrical conductivity and thermal stability tests revealed the superior performance of the Cu@Au NWs. The sheet resistance of Cu@Au NWs remained as low as 4 Ω sq-1 and showed exceptional thermal stability, with minimal resistance variation (R/Ro ~1.36) even after 36 h at 120 °C under ambient conditions. In contrast, the Cu-Au NTs suffered rapid oxidation and structural instability. The physical deposition approach holds significant promise for the development of robust, low-resistance electrodes for long-term applications in harsh environments. - COLLAPSE
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    27 January 2025

  • Research Paper

    Design of Nitrogen-Based Solid-State Lithium Conductor through High-Throughput Screening
    Jiyoon Yoon, Seonhye Park, Yewon Yang, Un Hwan Lee, Joonhee Kang
    The demand for secondary batteries is increasing rapidly with the popularization of electric vehicles and the expansion of wireless electronic devices. However, … + READ MORE
    The demand for secondary batteries is increasing rapidly with the popularization of electric vehicles and the expansion of wireless electronic devices. However, the most widely used lithium-ion batteries are subject to frequent fire incidents, limiting market growth. To avoid flammability, solid electrolyte-based systems are gaining attention for next-generation lithium-ion batteries. However, challenges such as limitations in ionic conductivity and high manufacturing costs require further research and development. In this study, we aim to identify a new nitrogen-based solid electrolyte material that has not yet been widely explored. We propose a methodology for selecting the final material through high-throughput screening (HTS), detailing the methods used for material selection and performance evaluation. In addition, we present ab initio molecular dynamics (AIMD) calculations and results for nitrogen-substituted materials with carbon and oxygen replacements, including Arrhenius plots, activation energy, and the predicted conductivity at 300K for the material with the highest Li-ion conductivity. While the performance does not yet surpass the ionic conductivity and activity of conventional solid-state electrolytes, our results provide a systematic framework for exploring and screening new solid electrolyte materials. This methodology can also be applied to the exploration of different battery materials and is expected to contribute significantly to the innovation of next-generation energy storage technologies. - COLLAPSE
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    27 January 2025

  • Research Paper

    Material Perception Data: Reliability Test and Perceptual Qualities Analysis of Material Classes Using Clustering Analysis

    재료지각 데이터: 군집분석을 이용한 신뢰성 검정과 재료의 지각성질 분석

    Jaeho Choi

    최재호

    Humans have the ability to perceive an object’s material and properties instantaneously, and use this information to prepare for future actions. Material … + READ MORE
    Humans have the ability to perceive an object’s material and properties instantaneously, and use this information to prepare for future actions. Material perception is not only an important factor for humans but also for artificial intelligence robots that are being developed. In addition, material perception is one of the important design requirements in selecting materials suitable for the products desired by consumers and pursued by designers. Because it is impossible to perform material perception using an exact formula, it is determined from tendencies that are identified in surveys. In this study, surveys with a binary selection were conducted, presenting participants with pairs of bipolar adjectives and asking them to choose one of two. After multiple surveys were conducted all the data were merged. Before merging the data, to ensure the reliability of the data homogeneity and correlation were tested using hierarchical clustering, correlation coefficient, and k-means cluster analysis. Afterwards, the merged data was used to analyze universal and comparable perceptual qualities of various material classes using relative frequency and hierarchical cluster analysis. - COLLAPSE
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    27 January 2025

  • Research Paper

    Improving the Electrochemical Performance of High-Nickel Cobalt-Free Cathode Coated with N-Doped Carbon Quantum Dots

    질소 도핑 탄소 양자점이 코팅된 하이니켈 무코발트 양극재의 전기화학 성능 향상

    Yun-Jae Song, Hyo-Jin Ahn

    송윤재, 안효진

    Lithium-ion batteries (LIBs) are widely used as essential power sources for electric vehicles and energy storage systems. Among various cathode materials, Li[Ni … + READ MORE
    Lithium-ion batteries (LIBs) are widely used as essential power sources for electric vehicles and energy storage systems. Among various cathode materials, Li[Ni0.9Mn0.1]O2 (NM90) has gained significant attention for enhancing the performance of LIBs due to its high energy density and nontoxicity. However, increasing the nickel content introduces challenges, including structural instability and cation mixing. To address these issues, we propose a surface coating strategy using nitrogen-doped carbon quantum dots (NCQDs). NCQDs provide high electrical conductivity and electrochemically active sites, so the NCQDs coating effectively enhanced both structural stability and electrical/ionic conductivity. The NCQDs were synthesized via a hydrothermal method, and NM90 were synthesized by co-precipitation. The fabricated NCQD/NM_5 electrode exhibited superior electrochemical properties, including a high initial capacity of 189.6 mAh/g, excellent rate performance, and an outstanding capacity retention of 81.5 % after 200 cycles in 1C. These superior results demonstrate that surface modification using the NCQDs strategy for Li[Ni0.9Mn0.1]O2 cathode materials will contribute to the further development of cycle stability and ultrafast performance in energy storage systems. - COLLAPSE
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    27 January 2025

  • Research Paper

    Microstructure and Mechanical Properties of AA1050/AA5052 Layered Sheet by Cold Roll-Bonding Process

    냉간압연접합공정에 의해 제조된 AA1050/AA5052 층상 판재의 미세조직 및 기계적 성질

    Hyeon-Jun Heo, Seong-Hee Lee

    허현준, 이성희

    A cold roll-bonding (CRB) process is applied to fabricate an AA1050/AA5052 layered sheet. In the process, commercial AA1050 and AA5052 sheets of … + READ MORE
    A cold roll-bonding (CRB) process is applied to fabricate an AA1050/AA5052 layered sheet. In the process, commercial AA1050 and AA5052 sheets of 1 mm thickness, 40 mm width and 300 mm length are stacked onto each other, and then reduced to a thickness of 0.5 mm through a 2-pass cold rolling process without lubricant. The roll-bonded AA1050/AA5052 layered sheet is then annealed for 1 h at various temperatures from 200 to 400 °C. The specimens annealed at temperatures below 250 °C showed a typical deformation structure in which the grains were elongated along the rolling direction. However, the specimens annealed at temperatures higher than 300 °C exhibited recrystallization structures in both the AA1050 and AA5052 regions. All the roll-bonded and subsequently annealed specimens showed an inhomogeneous distribution of hardness in the thickness direction, in which the hardness in the AA5052 regions was higher than that in the AA1050 regions. As the annealing temperature increased, the tensile and yield strengths decreased and the elongation increased gradually. The mechanical properties were compared to those of commercial AA1050 and AA5052 materials and CRBed AA5052-2L materials from a previous study. - COLLAPSE
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    27 January 2025
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Journal Informaiton Korean Journal of Materials Research Korean Journal of Materials Research
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