• 제목/요약/키워드: high-Tc

검색결과 1,528건 처리시간 0.031초

Emulsion 건조방법에 의한 고온초전도체 분말제조 (Preparation of High Tc Superconductor Powders by Emulsion Drying Method)

  • 엄우식;김호기
    • 한국재료학회지
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    • 제1권2호
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    • pp.71-76
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    • 1991
  • The superconducting powders in $YBa_2Cu_3O_{7-x}$ and Bi-Pb-Sr-Ca-Cu-O system were easily prepared from water in oil type emulsion by loading each cation into the aqueous phase. In $YBa_2Cu_3O_{7-x}$ system, the superconducting orthorhombic phase was formed by calcining at $750^{\circ}C$ for 10h in $O_2$. The size of the superconducting phase powders was submicron. The density of the sintered specimen using this powders was about 95% of the theoretical density and the resistance sharply decreases at about 90K, In Bi-Pb-Sr-Ca-Cu-O system the low Tc phase($(Bi, Pb)_2Sr_2Ca_1Cu_2O_y$) was formed by calcining at $800^{\circ}C$ for 10h in a low oxygen partial pressure of 1/20 atm The shape of clacined powder is thin plate of which size is about $2\mu\textrm{m}$ and thickness is smaller than $\mu\textrm{m}$. It was observed that the high Tc phase ($(Bi, Pb)_2Sr_2Ca_2Cu_3O_y$) was formed by sintering at $850^{\circ}C$ for 30h in oxygen pressure of 1/20 atm without intermediary grinding. The above sintered sample exhibited superconductivity with a Tc(zero)=105K.

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Bi-2223 고온초전도 전류리드의 제조 (Fabrication of Bi-2223 high-Tc superconducting current lead)

  • 하동우;오상수;류강식;장현만
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1996년도 하계학술대회 논문집 C
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    • pp.1660-1662
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    • 1996
  • Superconducting current lead is one of the promising applications of the oxide high-Tc superconductors, because they have the advantage of decreasing heat conduction to low temperature region, comparing with a conventional cooper alloy lead. High critical current density is a key factor for the applications such as current lead. $(Bi,Pb)_{2}Sr_{2}Ca_{2}Cu_{3}O_{x}$ high Tc superconductor hase been investigated in terms of critical current density. Bi-2223 superconducting current lead made by CIP and solid state sintering process. Bi-2223 current lead that heat treated at $836\;^{\circ}C$ for 240 h in 1/13 $PO_2$ had over $500\;A/cm^2$ of critical current density at 77K. We knew that the superconducting properties of tube type current leads were better than rods type of them. And we investigated the relation of Bi-2223 formation and heat treatment condition by XRD and SEM analysis.

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홍국고구마가 고지방식이를 급여한 흰쥐의 배변량 및 지질대사에 미치는 영향 (Effect of Diets with Red Yeast Sweet Potato Powder Supplement on Fecal Amount and Lipid Metabolism in Rats Fed a High-fat Diet)

  • 박주헌;최상윤;이경원;김성수;조경동;한찬규
    • 한국식품영양과학회지
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    • 제41권4호
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    • pp.487-493
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    • 2012
  • 홍국고구마가 고지방식이를 섭취한 흰쥐의 배변량 및 지질대사 개선에 미치는 영향을 조사하고자 SD계 수컷 흰쥐를 대상으로 실험 1기(6주)에 고지방식이를 급여하고, 실험 2기(4주)에 3종의 고구마분말(일반, 홍국, 자색)을 5% 첨가한 식이를 급여했을 때, 배변량은 홍국고구마군(RYSP)이 고지방대조군(CON)에 비해 유의하게 증가하였고(p<0.05), 장 통과시간 역시 RYSP군이 가장 짧았다. 분변 중 총콜레스테롤(TC) 함량은 일반고구마군(WFSP)과 홍국고구마군(RYSP)이 유의하게 높았고(p<0.05), 그중에서도 RYSP군이 더 높은 함량을 나타내었으며, 중성지방(TG) 농도는 RYSP군이 WFSP군과 PFSP(자색고구마)군에 비해 각각 9%, 26% 더 높았으나 유의성은 없었다. 반면 1일 총 지질배설량은 TC와 TG 모두 RYSP군이 CON군과 PFSP군에 비해 유의적으로 높았다(p<0.05). 혈청 중 TC 농도는 RYSP군이 CON군에 비해 유의적 차이 없이 20% 감소하였고, LDL-C 농도는 RYSP, PFSP군이 CON군보다 통계적으로 유의하게 낮았으며(p<0.05), TG 농도는 RYSP군이 실험군중 가장 낮았고 이는 WFSP군과 유의적인 차이가 있었다(p<0.05). 이상의 결과에서 홍국고구마 식이는 배변량을 증가시키고, 분변 중 지질 배설량을 다소 증가시키며, 혈청 지질 농도의 감소 효과를 확인할 수 있었다.

$^{99m}Tc-LDL$ (Low Density Lipoprotein)신티그라피를 이용한 동맥경화병소 진단 (Detection of Atherosclerotic Lesion with $^{99m}Tc-LDL$ Scintigraphy)

  • 김덕윤;고은미;우정택;김성운;양인명;김진우;김영설;김광원;최영길
    • 대한핵의학회지
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    • 제26권2호
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    • pp.257-264
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    • 1992
  • Diagnostic approaches such as angiography, ultrasound, computed tomography and nuclear magnetic resonance have limitation for contributing to the early clinical diagnosis of atherosclerosis. Recently, $^{99m}Tc-labelled$ low density lipoprotein was developed to detect early atherosclerotic lesion by external imaging with gamma camera. To determine whether $^{99m}Tc-LDL$ scintigraphy can visualize the active atherosclerotic lesion, rabbits were injected with $^{99m}Tc-LDL$, 3 months after feeding dietary fat (lanolin) and we obtained following results. 1) Labelling efficiency of $^{99m}Tc-LDL$ was $79\sim88%$. 2) Biodistribution study of normal rabbits with $^{99m}Tc-LDL$ revealed the high activities in spleen, adrenal gland, liver, kidney which are major organs of high metabolic rate of LDL. 3) Three months after feeding lanolin, serum cholesterol was markedly increased from $74{\pm}17mg/dl$ to $979{\pm}153mg/dl$ and histologic study of aorta after sacrificing the rabbit demonstrated marked atherosclerotic changes. 4) Atherosclerotic lesion of abdominal aorta which was confirmed with histologic study could be demonstrated in $^{99m}Tc-LDL$ scintigraphy after feeding lanolin for 3 months. In conclusion, the results of this preliminary investigation suggest that it may be possible to image active atheromatous lesion with $^{99m}Tc-LDL$. It is anticipated that this promising agent may allow the in vivo monitoring of preclinical atherosclerotic lesions and may be useful to evaluate the metabolic pathway of LDL in humans.

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$^{99m}Tc-MDP$를 이용한 Bone scan 시간(時間)에 관(關)한 고찰(考察) (A Study of Bone Scan Time by Use of $^{99m}Tc-MDP$)

  • 박성옥;이현배
    • 대한방사선기술학회지:방사선기술과학
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    • 제17권1호
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    • pp.77-86
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    • 1994
  • The bone scan reflects the metabolic reaction of bone to a disease process, whether neoplastic, traumatic or inflammatory. In normal bone tissue, the labeled diphosphate complexes accumulate in the perivascular fluid next to the marrow cavity at the interface between uncalcified and calcified bone matrix. HMDP has the most rapid plasma clearance among the commonly used diphosphonate followed by MDP and then HEDP. I have studied about bone scan time by use of $^{99m}Tc-MDP$, and got 336 images from 112 patients. The result obtained as follow; 1. Accumulation rate of $^{99m}Tc-MDP$ is higher than other age groups in below 30-year old group. 2. Accumulation rate, in 10year old group, is 75.85% on 120min. but other groups are most high on 180 min. 3. The density differants between bone and soft tissue increased with time. 4. Image contrast is good in younger group than old.

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음성지구 물관리자동화시스템의 용수공급 특성 (The Irrigation Characteristics of The Eumsung TM/TC system)

  • 고광돈;권순국
    • 한국농공학회:학술대회논문집
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    • 한국농공학회 2005년도 학술발표논문집
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    • pp.1-6
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    • 2005
  • Eumsung TM/TC system is composed of one control center, four reservoirs and twenty irrigation canal systems. In this paper we analyzed operation frequencies of the irrigation system to verify the effect of TM/TC system. Large facilities's operation frequency were more low then small thing and irrigation type was continuous irrigation. operation frequency was most high in may and june. usually water gate was operated once per 5-10 day. With these analysis we concluded that operators should operate irrigation facilities based on scientific technique and designer should make a proper choice in TM/TC system selection fit to the field.

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유역특성(流域特性)과 홍수도달시간(洪水到達時間)과의 상관해석(相關解析) (Analysis on Relations between Travel time and Watershed Characteristics)

  • 서승덕;임규동
    • Current Research on Agriculture and Life Sciences
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    • 제5권
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    • pp.158-167
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    • 1987
  • The purpose of this study is to inquire and analyse the relation between traveltime (Tc) and watetshed physical characteristics surveyed such as river length (L), Lea, river main slope (s), base length of time area diagram, and storage constant (k). The results obtained in this study are as follows. The average widths of watersheds were with the range from 4.6 kilometers to 16.7 kilometers. The shape factors of main stream ranged from 0.08 to 0.37. The average slopes to main 8tream were within the range of 1.7-5.5 meter per kilometer. The relation between the base length and traveltime from S. C. S. method, Rational method, and RZIHA+KRAVEN method were derived $Tc=0.524{\times}1.35^c$ (r=0.98), $Tc=0.628{\times}1.339^c$, (r=0.98), $Tc=0.667{\times}1.342^c$ (r=0.97). The base length of the time-area diagram (c) for the IUH was derived as $c=0.9(\frac{L.L_{ca}}{\sqrt{s}})^{0.35}$ and correlation coefficient was 0.98 which defined a high significance. The storage constant K, derived in this study was $K=8.32+0.0213{\frac{L}{\sqrt{s}}}$ with correlation coefficient (0.96). The relation between storage Constant and conventional formula were figured out $Tc=0.0003{\times}3.323^k$ (r=0.97). $Tc=0.00045{\times}3.268^k$ (r=0.99) and $Tc=0.0004{\times}3.26^k$ (r=0.963). The base length (c) and storage constant (k) of time-Area Diagram were very important parts that determined traveltime for flood events. In the estimate of travel time for predicting flood volume, the formula of $Tc=0.524{\times}1.35^c$ that would be available to apply the Nak - Dong river watershed area and homogeneous watershed characteristics was found.

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방사성동위원소표지 Liposome의 분포에 대한 실험적 연구 (Distribution of Radionuclide Labeled Liposome in Experimental Study)

  • 이범우;정재민;김상은;이동수;정준기;이명철;고창순;하성환
    • 대한핵의학회지
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    • 제24권2호
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    • pp.317-324
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    • 1990
  • Liposome was labelled with $^{99m}Tc$ after negative charged liposome was formed with combination of a few lipid components. $^{99m}Tc$ liposome was injected through the tail vein of C3H mice bearing fibrosarcoma and biodistribution of $^{99m}Tc$ liposome was evaluated. The results were as follows: 1) We confirmed formation of liposome which was small unillamellar and multilamellar vesicles. 2) In this experiment the optimal concentration of $SnCl_2$ was $156{\mu}g/ml$ to label liposome with $^{99m}Tc$ and labelling efficiency was 95%. 3) The labelled liposome was stable when it was incubated with human serum for 24 hours. Mean labelling efficiency was 94% at 24 hour. 4) The main uptake sites of Tc-99m liposome were liver and spleen. It showed significantly higher uptake than $^{99m}Tc$ HSA (p < 0.001). 5) $^{99m}Tc$ liposome uptake in tumor tissue was not significantly higher than $^{99m}Tc$ HSA uptake. In conclusion, $^{99m}Tc$ liposome disclosed high labelling efficiency and was highly stable. Liver and spleen were main uptake sites of $^{99m}Tc$ liposome. The uptake mechanism of $^{99m}Tc$ liposome also seemed to be different from that of $^{99m}Tc$ HSA. We conclude that $^{99m}Tc$ liposome would be a promising agents for the imaging of some tumor.

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