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        검색결과 8,456

        77.
        2024.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Pure SnO2 has proven very difficult to densify. This poor densification can be useful for the fabrication of SnO2 with a porous microstructure, which is used in electronic devices such as gas sensors. Most electronic devices based on SnO2 have a porous microstructure, with a porosity of > 40%. In pure SnO2, a high sintering temperature of approximately 1300°C is required to obtain > 40% porosity. In an attempt to reduce the required sintering temperature, the present study investigated the low-temperature sinterability of a current system. With the addition of TiO2, the compositions of the samples were Sn1-xTixO2-CoO(0.3wt%)-CuO(2wt%) in the range of x ≤ 0.04. Compared to the samples without added TiO2, densification was shown to be improved when the samples were sintered at 950°C. The dominant mass transport mechanism appears to be grain-boundary diffusion during heat treatment at 950°C.
        4,000원
        78.
        2024.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigated the effect of manufacturing variables (including heating temperature) on the physicochemical properties of nanoemulsion delivery system (NDS) prepared with WPI/Inulin Maillard conjugate and to study how the physicochemical properties of NDS affected the bioaccessibility of lycopene. The functional properties of the WPI/Inulin Maillard conjugate were determined using the OPA method, interfacial tension, and EAI. The physicochemical and morphological properties of NDS were measured using Zetasizer and TEM, respectively. The bioaccessibility of lycopene in the WPI/Inulin Maillard conjugate based NDS was measured using a spectrophotometer. As the pH and heating temperature increased, the Maillard conjugation efficiency increased significantly (p<0.0001). The emulsifying properties of the WPI/Inulin Maillard conjugate were greater than those of WPI. A WPI/Inulin Maillard conjugate based NDS with a size of ~180 nm was observed in TEM images while the droplet size of the WPI/Inulin Maillard conjugate based NDS was smaller than that of the WPI based NDS. During in vitro digestion, no significant changes in the droplet size and PDI of NDS were observed in the mouth and stomach phases, whereas in the intestinal phase, the droplet size and PDI increased significantly (p<0.0001). Moreover, the bioaccessibility of lycopene in the WPI/Inulin Maillard conjugate based NDS significantly increased (p<0.0001), compared with that of the WPI based NDS. There was a significant (p<0.05) increase in the bioaccessibility of lycopene with a decrease in the interfacial tension and droplet size of NDS. In conclusion, WPI/Inulin Maillard conjugate based NDS can be used to enhance the bioaccessibility of lycopene.
        4,200원
        79.
        2024.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the heating performance of a variable capacity A/C system was experimentally studied. A psychrometric calorimeter was used to obtain performance data of the A/C system using PWM(pluse width modulation) method and compare it with the compressor discharge temperature correlation equation. Heating capacity, COP, and compressor discharge temperature were obtained by changing indoor and outdoor temperatures, refrigerant amount, and loading duty. The following results were obtained by selecting 5 types of refrigerant amount, 3 types of outdoor temperature (fixed indoor temperature), and 2 types of loading duty. As the outdoor temperature increases, heating capacity and COP increase. Heating capacity was affected by both outdoor temperature and loading duty. However, COP was more influenced by outdoor temperature. The effect of increasing the amount of refrigerant on the performance of the A/C system was not significant. Additionally, the temperature deviation between the existing compressor discharge temperature correlation equation and the heating experiment data was about 5.1℃ at the maximum loading duty.
        4,000원
        80.
        2024.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The laser power has been continually increased since the laser was developed in the mid-20th century. Achieving higher laser power requires not only enhancing the cooling performance of laser systems but also addressing the potential degradation of optical characteristics due to thermal deformation induced by laser beam absorption in a mirror. This study delves into the thermal deformation characteristics of mirrors in high-power laser systems. To minimize thermal deformation by heat absorption, Zerodur, known for its low coefficient of thermal expansion, was employed as the mirror material. Various configurations including circular, rectangular, and spline shapes were implemented on a solid mirror structure. Furthermore, two different diameter of a mirror, 300mm and 400mm, were considered to investigate the size effect of the high-power laser beams. Also, three different transmitted beam power were adopted: 50W, 250W, and 500W. Based on the finite element analysis for the thermal deformation, the deformation characteristics of the different types of mirror structures were investigated and analyzed for high-power laser systems.
        4,000원
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