• Research Paper

    Effects of Crystalline Admixtures on Mechanical Properties and Durability of Concrete at Different Ambient Temperatures
    Hao Li, Qian Wang, Yi Ding, Zilong Wu, Qinglin Huang, Haixia Ji, Wei Xu, Yanyan Wang, Kai Huang, Qifang Ren, Won-Chun Oh
    Sodium sulfate, as a commonly used early strengthening agent, has been widely used in different areas. Because of its sulfonic acid group, … + READ MORE
    Sodium sulfate, as a commonly used early strengthening agent, has been widely used in different areas. Because of its sulfonic acid group, sodium sulfate is also used as a cement capillary crystal waterproof material. However, temperature has a significant effect on concrete mixed with sodium sulfate. The effect of sodium sulfate on the early hydration rate at different temperatures was studied by conducting a time and hydration thermal analysis. The effects of sodium sulfate on the mechanical properties of concrete at different temperatures were studied through compressive strength experiments. Impermeability at different temperatures was studied by testing resistance to chloride ion penetration and resistance to water penetration. The effect of resistance to sulfate attack was also experimentally. The hydration products were analyzed by electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The experimental results showed that at low temperature, sodium sulfate can accelerate the early hydration reaction rate, and the effect becomes weaker with increasing temperature. At low temperature, the addition of sodium sulfate can effectively improve the degree of hydration, and enhance the permeability resistance and ion erosion resistance of the matrix. - COLLAPSE
    PDFXMLCitation
    ReferencesInformation
    27 March 2025

  • Research Paper

    Development of Gas Sensors for Measuring Gas Emission and Diffusion Coefficient in Gas Charged EPDM Polymer Using Volumetric and Manometric Analysis
    Ji Hun Lee, Sang Koo Jeon
    Gas sensors are crucial devices in various fields including industrial safety, environmental monitoring, gas infrastructure and medical diagnosis. These sensors measure specific … + READ MORE
    Gas sensors are crucial devices in various fields including industrial safety, environmental monitoring, gas infrastructure and medical diagnosis. These sensors measure specific gases in different environments, guaranteeing operational safety and efficiency through precise on-site measurements. Designed for high sensitivity, stability and reliability, gas sensors must also be cost-effective, quickly responsive and compact. To address these diverse requirements, we have developed two types of gas sensors based on the volumetric and the manometric method. These sensors operate by measuring the gas volume and the pressure changes, respectively, of the emitted gas. These sensors are capable of determining gas transport parameters such as gas uptake, solubility and diffusion coefficient for gas-charged polymers in high pressure environment. The sensors provide rapid responses within one second and can measure gas concentrations ranging from 0.01 wt ppm to 1500 wt ppm with adjustable sensitivity and measurement ranges. Performance evaluations demonstrate the sensors' reliability, adaptability to varying measurement ranges and stability under temperature and pressure fluctuations. As a result, this sensor system facilitates the real time detection and analysis of gas transport properties in pure gases including H₂, He, N₂, O₂ and Ar, making it suitable for pure gas sensing. - COLLAPSE
    PDFXMLCitation
    ReferencesInformation
    27 March 2025

  • Research Paper

    Designing Synthesis Processes to Enhance the Luminescence Properties of SrAl2O4:Eu

    SrAl2O4:Eu 소재의 발광 특성 향상을 위한 합성 공정 설계

    Youngseung Choi, Chaeyoun Kim, Seongju Park, Jinu Park, Sung-Jin Yang, Ji-Seong Go, Byungha Shin

    최영승, 김채연, 박성주, 박진우, 양성진, 고지성, 신병하

    Eu-doped SrAl2O4 is a promising thermoluminescent and mechanoluminescent material with high brightness and stability, making it suitable for various … + READ MORE
    Eu-doped SrAl2O4 is a promising thermoluminescent and mechanoluminescent material with high brightness and stability, making it suitable for various luminescent devices. In this study, SrAl2O4:Eu was synthesized using a solid-state reaction method, and the effects of reducing atmosphere and high-temperature synthesis conditions on its luminescence properties were systematically analyzed. The luminescence characteristics of SrAl2O4:Eu were found to be highly sensitive to synthesis temperature, atmosphere, and Eu doping concentration, and optimal conditions were determined. A comparison of SrAl2O4:Eu synthesized at 1,300 °C under air and reducing atmospheres revealed that the reducing atmosphere plays a critical role in stabilizing Eu2+ ions, forming a single-phase SrAl2O4, and establishing luminescence centers. Notably, SrAl2O4:Eu synthesized at 1,600 °C in a reducing atmosphere achieved a photoluminescence quantum yield (PLQY) of 43 % and a maximum luminance of 2,030 Cd/m2, showing significant improvement in luminescence efficiency compared to samples synthesized at 1,300 °C. When Eu doping concentrations were adjusted from 1 % to 20 %, the highest luminescence performance was observed at 10 % doping, while excessive doping (20 %) increased non-radiative recombination pathways, and no further improvement in luminescence efficiency was observed. X-ray Diffraction (XRD) and Photoluminescence (PL) analyses elucidated the effects of synthesis conditions on the structural stability and luminescence properties of SrAl2O4:Eu, and the optimal reducing atmosphere and high-temperature synthesis conditions are proposed. This study provides a synthesis strategy for enhancing the luminescence properties of Eu-doped SrAl2O4 and lays the groundwork for the development of high-performance thermoluminescent and mechanoluminescent materials. - COLLAPSE
    PDFXMLCitation
    ReferencesInformation
    27 March 2025
리스트형 보기썸네일형 보기
Journal Informaiton Korean Journal of Materials Research Korean Journal of Materials Research
Online Submission
  • scopus
  • NRF
  • KOFST
  • crossref crossmark
  • crossref cited-by
  • crosscheck
  • open access
  • ccl
Journal Informaiton Journal Informaiton - close