• 제목/요약/키워드: High-$T_{c}$

검색결과 4,289건 처리시간 0.036초

육방정 페라이트의 결정과 Block 구조 (Crystal and Block Structures of Hexagonal Ferrites)

  • 신형섭
    • 한국세라믹학회지
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    • 제49권3호
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    • pp.205-215
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    • 2012
  • It has been studied the crystal and block structures of the hexagonal ferrites with M, W, Y and Z types prepared by various coprecipitation-oxidation method. The structures have been refined with a Rietveld analysis of the powder X-ray diffraction pattern with high precision ($R_{WP}$ <0.09, $R_I$ <0.03). The density difference between the S-blocks was proportioned to the cobalt contents in hexagonal ferrites, but that between the R or T-blocks was relatively small. Compared with the blocks and cation-oxygen polyhedra in BaM ($BaFe_{12}O_{19}$), those were bulky to the normal direction for the c-axis in $Co_2W$ ($BaCo_2Fe_{16}O_{27}$) and to the parallel direction for the c-axis in $Co_2Y$ ($Ba_2Co_2Fe_{12}O_{22}$) and $Co_2Z$ ($Ba_3Co_2Fe_{24}O_{41}$). The S-blocks of $Co_2W$, $Co_2Y$, and $Co_2Z$ were unstable and distorted. Because the T-block of $Co_2Z$ was unstable, the T-block was decomposed into the Ba-rich phase and $Co_2W$ at high temperatures above $1200^{\circ}C$. A standard powder X-ray diffraction pattern for $Co_2Z$ was proposed as well.

고온초전도 마이크로스트립 안테나의 온도 종속 초고주파 특성 (Microwave Properties of High Tc Superconducting Microstrip Antenna with Temperature Dependence)

  • 정동철;최명호;강형곤;임성훈;한병성
    • 한국초전도학회:학술대회논문집
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    • 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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    • pp.124-128
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    • 1999
  • We report microwave properties of high-T$_c$ superconducting (HTS) microstrip antennas without impedance matching circuits, where the impedance mismatching is obvious under the critical temperature (T$_c$). The superconducting thin films used in this report were YBa$_2Cu_3O_{7-x}$ (YBCO) films deposited on MgO substrates produced by pulse laser deposition (PLD) technique. At around T$_c$, 86 K the reflection coefficient rapidly drops, and the standing wave ratio (SWR) becomes almost unity, and the characteristic impedance based on the Smith chart is nearly 50 ${\Omega}$. The reflection coefficient and the SWR of the HTS microstrip antenna were - 62.52 dB and 1.0015, respectively, at the resonant frequency of 11.812 CHz at 86 K.

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고온초전도 다층박막의 성장과 마이크로파 필터의 개발 (Growth of high-$T_{c}$ Superconducting Multilayer thin films and Fabrication of Microwave Filter)

  • 강광용;김철수;곽민환
    • 한국초전도저온공학회:학술대회논문집
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    • 한국초전도저온공학회 2003년도 학술대회 논문집
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    • pp.287-290
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    • 2003
  • For microwave device applications, c-axis oriented high temperature superconducting YBa$_2$Cu$_3$O$_{7-{\delta}}$ (HTS-YBCO) epitaxial thin films on the r-cut sapphire substrate(Al$_2$O$_3$) were prepared. In order to reduce the lattice mismatch with a substrate and to enhance the crystallity of HTS thin films, CeO$_2$ buffer layer on the r-cut sapphire substrate was grown by the RF-magnetron sputtering. The YBCO films on the CeO$_2$ buffer layer were deposited using the pulsed-laser deposition (PLD) method. These HTS YBCO /CeO$_2$/Al$_2$O$_3$ multilayer thin films(30 $\times$ 30 mm$^2$) routinely exhibited a critical temperature(T$_{c}$) of 89 K from the R-T measurement. Using HTS YBCO/CeO$_2$ /Al$_2$O$_3$ multilayer thin film. We fabricated and characterized the microwave passive devices (planar type filters) with cryopack-age such as the coupled -line type low-pass filter (LPF) and the open-loop meander type bandpass filter (BPF).filter (BPF).).

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뒤꿈치 인솔착용과 시각통제 유무가 하이힐 착용 시 균형관련 지수에 미치는 영향 (Influence of Heel Insole and Visual Control on Body Sway Index with High-heeled Shoes)

  • 윤정규
    • 대한물리의학회지
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    • 제9권4호
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    • pp.407-413
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    • 2014
  • PURPOSE: We investigated the influence of heel insole and visual control on body sway index with high-heeled shoes. METHODS: The subjects of this study were 61 healthy students. None of the participants had any orthopedic or neurologic alterations. C90 area, C90 angle, trace length, sway average velocity were measured using a force plate by BT4. The variables were measured both with insole and without insole when wearing high-heeled shoes under the conditions of eyes open and eyes closed. The collected data were analyzed using the Kolmogorov-Smirnov test and paired t-test. RESULTS: When wearing high-heeled shoes with insole under the conditions of eyes open, trace length, C90 area, velocity were significantly more decreased than without insole (p<.01). When wearing high-heeled shoes with insole under the conditions of eyes closed, only C90 area was significantly more decreased than without insole (p<.05). When wearing high-heeled shoes with insole under the conditions of eyes open, trace length, C90 area, velocity were significantly more decreased than under the conditions of eyes closed (p<.01). CONCLUSION: The present study demonstrates that the use of high-heeled shoes with insole supported from heel to midfoot more increased static balance than without insole under the conditions of eyes open.

마쇄보리 사료 급여가 비육후기 거세 한우의 도체 및 식육 특성에 미치는 효과 (Effect of Dietary Cracked Whole Barley on the Carcass Characteristics and Meat Composition in Hanwoo Steers)

  • 이상무
    • Journal of Animal Science and Technology
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    • 제53권4호
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    • pp.367-375
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    • 2011
  • 본 연구는 마쇄보리 사료의 급여 수준이 비육 후기 한우 거세우의 사료섭취량, 일당증체량, 육량, 육질, 일반성분, 무기물 및 색도에 미치는 영향을 검토하고자 급여 기준(배합사료 기준으로 0%, 10%, 20%, 30%, 40% 마쇄보리 첨가)을 5처리 하여 실시하였다. 본 실험에서 얻어진 결과를 요약해 보면 다음과 같다. 평균 사료섭취량은 T2 > T3 > T4 > T1 > C구 순으로, 일당 증체량은 T2 > T3 > T4 > T1 > C구 순으로 높게 나타났다. 등지방 두께, 육량 지수 및 등심단면적은 각각 C, T4 및 T1구에서 높게 나타났다. 특히 등지방두께는 마쇄 통보리 첨가구(T1, T2, T3 및 T4)가 C구보다 낮게 나타났다. 근내지방도, 조직감 및 육질등급은 T1구가 가장 높았던 반면(P<0.01, 0.05) 성숙도, 지방색 및 육색은 상호 처리간 유의적인 차이가 없었다. 조지방 함량은 T1구가 17.59%로 가장 높았던 반면 T4구가 7.47%로 가장 낮게 나타났다(P<0.05). 조단백질, 조회분 및 가용무질소물 함량은 처리간 유의적인 차이를 보이지 않았다. 에너지가에 있어서는 마쇄보리 첨가구(T1, T2, T3, T4)구가 C구에 비하여 모두 높게 나타났다(P<0.01). Ca, Cu, K, Mg, Mo, Na 및 Zn 함량은 모두 C구에서 높게 나타났으며(P<0.05), Co 함량은 T2구에서 높게 나타났다(P<0.01). 명도($L^*$)는 C구에 비하여 마쇄보리 첨가구(T1, T2, T3, T4)에서 모두 높게 나타났지만 유의적인 차이는 없었다. 적색도($a^*$)는 T1구가 20.96으로 다른 구에 비하여 높게 나타났으며(P<0.05), 황색도 ($b^*$)는 C구에 비하여 마쇄보리 첨가구가 모두 낮게 나타났다. 그리고 모두 마쇄보리 첨가량이 증가할수록 떨어지는 것으로 나타났다. 이상 결과를 종합해 보면 마쇄 보리 첨가량이 10%인 T1구는 다른 구에 비하여 등심단면적, Marble score, 육질등급 및 명도가 다른 구에 비하여 높은 것으로 나타났다.

Adiponectin gene SNP 276G${\rightarrow}$T, nutrient intakes, and cardiovascular disease risk in Korean type 2 DM patients

  • Yu, So-Young;Ryu, Han-Kyoung;Park, Hee-Jung;Choi, Young-Ju;Huh, Kap-Bum;Kim, Wha-Young
    • Nutrition Research and Practice
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    • 제1권4호
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    • pp.363-370
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    • 2007
  • Single nucleotide polymorphism (SNP) in adiponectin gene has been associated with insulin resistance, diabetes, and cardiovascular disease (CVD). This study was performed to investigate the association of SNP 276G${\rightarrow}$T at adiponectin gene with CVD risk factors in Korean type 2 diabetes mellitus (DM) patients. The subjects were 351 type 2 DM patients visited a DM clinic in Seoul, and the patients with known CVD were excluded. The adiponectin SNP 276G${\rightarrow}$T was analyzed and dietary intakes were assessed by a Food Frequency Questionnaire. The prevalence of G/G, G/T, and T/T genotype was 47.6%, 43.3%, and 9.1%, respectively. Male subjects with T/T genotype showed significantly lower level of adiponectin and HDL-cholesterol and significantly higher C-reactive protein (CRP) level compared to G/G and G/T genotypes. In G/G genotype, protein intake was negatively correlated to body weight, BMI, and waist circumference, and there were positive correlation between carbohydrate intake and BMI, waist-hip ratio, and ApoB/apoA-1 ratio in G/T genotype. However, in T/T genotype, there was no significant association between macronutrient intakes and anthropometric and hematological values. In conclusion, CVD risk would be high in type 2 DM patients with T/T genotype, and the association of macronutrient intakes with anthropometric and hematologic factors was different among the three adiponectin genotypes. These results may imply the need for different dietary management regime according to adiponectin genotype to lower CVD complications in Korean type 2 DM patients.

AZ31 Mg 합금의 가공 조건에 따른 고온 성형성 연구 (Effect of Processing Variables on the High Temperature Formability of AZ31 Mg alloy)

  • 이병호;신광선;이종수
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2004년도 춘계학술대회 논문집
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    • pp.80-83
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    • 2004
  • High temperature deformation behavior of AZ31 Mg alloy was investigated in this study on the basis of a processing map $(\varepsilon\approx0.6)$. To construct a processing map, compression tests were carried out at wide range of temperatures and strain rates $(T=250\~500^{\circ}C,\;\varepsilon=10^{-4}\~100/s)$. Two regions of high deformation efficiency $(\eta)$ were identified as: (1) a dynamic recrystalization (DRX) domain at $250^{\circ}C$ and 1/s and (2) a superplasticity domain at $450^{\circ}C$ and $10^{-4}/s$. Possible deformation mechanisms operating at high temperature were discussed in relation to the activation energy. A two-stage deformation method was found to be effective in enhancing the superplasticity of AZ31 Mg alloy. From the two-stage deformation method, tensile elongation of $1200\%$ was obtained at the superplastic domain.

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터빈 디스크용 스테인리스강의 고온 인장 및 저주기 피로 물성 측정 (Evaluation of high temperature tensile behavior and LCF properties of stainless steel for turbine disks)

  • 임형대;박철규;이광주;임성한;김춘택
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2007년도 추계학술대회 논문집
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    • pp.334-337
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    • 2007
  • Austenitic stainless steel is used as high temperature components such as gas turbine blade and disk because of its good thermal resistance. In the present investigation, tensile and low cycle fatigue(LCF) behavior of stainless steel for turbine disks was studied at wide temperature range $20^{\circ}C\;{\sim}\;750^{\circ}C$. In the tensile tests, it was shown that elastic modulus, yield strength, ultimate tensile strength decreased when temperature increased. The effect on fatigue failure of the parameters such as plastic strain amplitude, stress amplitude and plastic strain energy density was also investigated. Coffin-Manson and Morrow models were used to adjust experimental data and predict the fatigue life behavior at different mean strain values during cyclic loading of high temperature components.

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