• Title/Summary/Keyword: $J_c$ (B)

Search Result 5,396, Processing Time 0.037 seconds

Effects of Nano FexC Addition on Superconducting Properties of MgB2 (MgB2 초전도 특성에 대한 나노 FexC 첨가 효과)

  • Lee, Dong-Gun;Lee, Ji-Hyun;Jun, Byung-Hyuk;Park, Soon-Dong;Uhm, Young-Rang;Park, Hai-Woong;Kim, Chan-Joong
    • Journal of Powder Materials
    • /
    • v.19 no.2
    • /
    • pp.146-150
    • /
    • 2012

  • The effects of nano $Fe_xC$ addition to superconducting properties of $in$ $situ$ processed $MgB_2$ superconductors was examined. 0.1 wt.% and 1 wt.% nano $Fe_xC$ powders were mixed with boron and magnesium powders by ball milling. The powder mixtures were made into pellets by uniaxial pressing. The pellets were heat-treated at $700^{\circ}C-900^{\circ}C$ in argon atmosphere for $MgB_2$ formation. It was found by powder X-ray diffraction that the raw powders were completely converted into $MgB_2$ after the heat treatment. The superconducting transition temperature ($T_c$) and critical current density ($J_c$), estimated from susceptibility-temperature and $M-H$ curves, were decreased by nano $Fe_xC$ addition. The $T_c$ and $J_c$ decrease by nano $Fe_xC$ addition are attributed to the incorporation of iron and carbon with $MgB_2$ lattices (Fe substitution for Mg and C substitution for B) due to the high reactivity of the nano $Fe_xC$ powder.

  • https://doi.org/10.4150/KPMI.2012.19.2.146 인용 PDF KSCI

Study of $MgB_2$ Films Grown on Various Impurity Layers by using HPCVD Method (혼성물리화학기상 증착법으로 여러가지 불순물층 위에 제조한 $MgB_2$ 박막에 대한 연구)

  • Park, S.W.;Seong, W.K.;Jung, Soon-Gil;Kang, W.N.
    • Progress in Superconductivity
    • /
    • v.10 no.1
    • /
    • pp.35-39
    • /
    • 2008

  • By using the hybrid physical-chemical vapor deposition (HPCVD) technique, we have fabricated $MgB_2$ thick films on $Al_{2}O_3$ substrates with various impurity layers of Ni, Ti, and SiC. We have found a significant enhancement of the critical current density ($J_c$) for $MgB_2$ films grown on impurity layered substrates, indicating that additional impurity layers were provided as possible pinning sites by chemical doping in $MgB_2$ films. All samples doped by Ni, Ti, and SiC were observed to have high superconducting transition temperatures of 39 - 41 K. The $J_c$ of $MgB_2$ films grown on SiC impurity layered substrates showed three times higher than that of undoped films at high magnetic fields above 1 T.

  • PDF

An experimental study on the performance of a window system air-conditioner using R407C and R410B (R407C 및 R410B 적용 창문형 에어컨의 성능에 관한 실험적 연구)

  • Kim, M.H.;Shin, J.S.;Kim, K.J.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.9 no.4
    • /
    • pp.536-544
    • /
    • 1997

  • This study presents test results of a residential window system air-conditioner using R22 and two potential alternative refrigerants, R407C and R410B. A series of performance tests was performed for the basic and liquid-suction heat exchange cycle in a psychrometric calorimeter test facility. For R407C, the same rotary compressor was used as in the R22 system. However, compressor for the R410B system was modified to provide the similar cooling capacity. The evaporator circuit was changed to get a counter-cross flow heat exchanger to take advantage of zeotropic mixture's temperature glide, and liquid-line suction-line heat exchange cycle was also considered to improve the performance of the system. Test results were compared to those for the basic R22 system.

  • PDF

Accuracy analysis of artificial respiration and chest compressions when performing CPR using a mannequin by college students (대학생의 마네킹을 이용한 심폐소생술 시행 시 인공호흡과 흉부압박의 정확도 분석)

  • Jeon Jai-In
    • The Journal of the Convergence on Culture Technology
    • /
    • v.9 no.5
    • /
    • pp.167-173
    • /
    • 2023

  • The purpose of this study was to analyze the accuracy of artificial respiration and chest compressions using CPR mannequins for university students. First, in the number of chest compressions, subjects A, F, H, I, and J showed similar numbers from 60 to 63, respectively, which were much lower than the standard. Subjects B, D, E, and G showed 90 to 91 times, maintaining the normal range. However, C was rather high with 119 times. Second, the depth of chest compression was 58.60mm, and most of them were deeply compressed. Subject C was close to normal at 51mm, and subjects A to J were significantly higher at 55mm to 62mm. The reason seems to be the result of an unstable psychological state with no experience of chest compressions and a lack of self-confidence. Third, in terms of accuracy, subject E showed the lowest accuracy at 12%, and A~J showed 33%~80%. Experiment subject B showed 95% accuracy, which seems to be the result of D accurately recognizing the chest compression point through theoretical training during military service.

  • https://doi.org/10.17703/JCCT.2023.9.5.167 인용 PDF