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- 저자 : Yu-Ju Shin(Yu-Ju Shin ) (검색결과 524 건)
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층상구조 산화물 Na_(x)Ni_(x/2)Ti_(1-x/2)O₂의 합성과 구조적 특성
신유주,곽지현 가톨릭대학교 자연과학연구소 1998 자연과학논문집 Vol.19 No.-
층상구조 산화물 Na_(x)Ni_(x/2)Ti_(l-x/2)0₂(0.60≤X≤1.0)이 고상합성법에 의해 Ar 분위기하에서 950℃-1100℃로 가열하여 합성되었다. 단일상 영역은 0.75≤x≤1.0에서 rhombohedral(O3), 0.60≤x≤0.75에서는 primitive hexagonal 상(P2)으로 결정되었고, x<0.60은 층상구조와 함께 pruderite 구조상이 공존하는 혼합상 영역이었다. 격자상수 a는 x가 감소함에 따라 단순감소 하였고 c는 반대로 증가하는 것이 관측되었는데 이는 Ni^(2+)와 Ti^(4+) 이온 반경의 차, (Ni/Ti)O₂ 층간의 정전기적 반발력, (Ni/Ti)O_(6) 정팔면체의 trigonal distortion 정도와 관련지어 논의되었다. O3에서 P2로의 구조전이 과정은 (Ni/Ti)-O와 Na-O간 경쟁적인 공유-이온 결합성의 변화에 기인하는 것으로 이해되었다. Na_(0.67)Ni_(0.33)Ti_(0.67)O₂의 경우 Rietvelt 분석법을 이용하여 그 결정구조를 결정하였다. Layer-type oxides Na_(x)Ni_(x/2)Ti_(l-x/2)0₂(0.60≤x≤1) have been prepared for the first time by solid-state reaction by heating the appropriate mixtures of starting materials at 950℃-1100℃ under Ar ambience. Two consecutive single phases were observed, rhombohedral(03) phase for 0.75≤x≤1.0 and hexagonal one(p2) for 0.60≤x<0.75, and a mixed-phase appeared including pruderite phase with x<0.60. Lattice parameter a decrease with x, while c increases as x diminishes. Such behaviors have been discussed on the basis of the difference of ionie radii between Ni^(2+) and Ti^(4+), the electrostatic repulsion of (Ni/Ti)0₂ slabs and the evolution of trigonal distortion of (Ni/Ti)0_(6) octahedra. Structural transition from 03 to P2 has been understood due to the competitive iono-covalency between (Ni/Ti)-0 and Na-0 bonds. As for Na_(0.67)Ni_(0.33)Ti_(0.67)O, the crystal structure has been determined by the Rietveld profile-analysis method.
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층상구조 산화물 Na_(x)Co_(x/2)Ti_(1-x/2)O₂(0.66≤x≤1)의 합성 및 결정화학 연구
신유주,곽지현 가톨릭대학교 자연과학연구소 1997 자연과학논문집 Vol.18 No.-
층상구조 산화물 Na_(x)Co_(x/2)Ti_(1-x/2)O₂(0.66≤x≤1)이 고상합성법에 의해 Ar 분위기, 950℃에서 합성되었다. 단일상 영역은 0.75≤x≤1에서 rhombohedral, x=0.66에서는 primitive hexagnonal 상으로 결정되었고, 0.66<x<0.75에서는 두 개의 상이 공존하는 상 경계가 존재하였다. 두 구조의 결정 화학적 논의가 조성과 연관되어 공유-이온 결합성을 중심으로 이루어졌다. 또한 온도에 따른 자화율 거동을 분석한 결과, 두 구조 내에서 Co^(2+) 이온은 high-spin(S=3/2; ⁴T) 상태임을 알 수 있었고, 자기적 상호 작용에 대해서도 논의되었다. Layer-type oxides Na_(x)Co_(x/2)Ti_(1-x/2)O₂(0.66≤x≤1) have been prepared for the first time by solid-state reaction by heating the appropriate mixtures of starting materials at 950℃ under Ar ambience. They exhibit two kinds of structure according to x, respectively rhombohedral one for 0.75≤x≤1, and primitive hexagonal for x=0.66. Discussion of crystal chemistry of both structure has been made mainly focused to the iono-covalency of Na-O, and correlated to the chemical composition. Magnetic susceptibility measurements confirmed the high-spin state(S=3/2; ⁴T) of Co^(2+) ions in both structures and their magnetic interactions has been also discussed.
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신원철,윤주천,김갑수,최승락,이근억,유주현 江原大學校 産業科學硏究所 1981 産業技術硏究 Vol.1 No.-
In order to use as a starter after drying, optimum growth conditions of Str. thermophilus and L. bulgaricus were investigated. The results were as follows. The growth of Str. thermophilus was reached at stationary phase after 12 hours incubation and L. bulgaricus was after 6 hours. Str. thermophilus was grown well, in the medium containing 10% of skim milk, 2%5 of sucrose, 0.1% of KCl and 0.015%(v./v.) of soy-sauce. In the case of L. bulgaricus, 10% of skim milk, 2% of glucose, 0.5% of bacto-peptone, 0.1% of K₂HPO₄ and 0.02% of pyridoxine was suitable for the maximum growth.
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김기석,신유주 가톨릭대학교 자연과학연구소 2005 자연과학논문집 Vol.26 No.-
염료감응형 태양전지에 적용되는 나노결정형 ZnO 전극을 Ti(OBu)_(4)과 Si(OMe)_(4)으로 표면에 나노코팅을 하였다. 그 결과 루테늄 염료의 화학흡착 기능기인 카르복실 산에 대한 안정성이 크게 향상되었다. 단순한 ZnO 전극은 좋지 않은 광전류-전압 거동과 IPCE 거동을 보여 주는 반면, 표면처리된 전극은 에너지 변환 효율이 약 10배가 증가하였다. 이러한 성능 향상의 원인을 전자현미경, X-선 회절분석, UV-VIS 분광학 및 광전특성을 조사하여 고찰하였다. The surface nanoystalline ZnO electrode has been treated with Ti(OBu)_(4) or Si(OMe)_(4) to improve its stability to acidic anchoring group of Ruthenium dye〔N719〕. While bare ZnO electrode exhibited poor photovoltaic properties including I-V curve and IPCE values, surface-treated ZnO electrode showed a remarkable enhancement of energy conversion efficiency of about 10 times. The origin of this striking enhancement was investigated by comparing the physical and chemical properties of ZnO electrode via SEM, XRD, and UV-VIS spectroscopy, and discussed on the bases of improved surface stability of ZnO particles.
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송효경,신유주 가톨릭대학교 자연과학연구소 2003 자연과학논문집 Vol.24 No.-
새로운 비양론적 페로브스카이트(perovskite) 전이금속 산화물 Li_(0.33)Sr_(0.34+x)Sc_(x)Nb_(1-x)O₃, Li_(0.33)Sr_(0.34+x-y)Sc_(x)La_(y)Ta_(1-x)O₃을 고체 합성법으로 고온합성 하였다. 이들은 모두 정방형 구조를 갖고 있으며, 조성에 따라 단위세포와 A-자리 공극의 농도 및 공유결합성의 변화를 보여준다. 이들의 이온전도도는 300-770K 영역에서 AC-impedence 측정법으로 측정되었다. 이들이 상온 전도도는 10^(-5)Scm^(-1)정도를 나타내었고, 온도가 증가하면서 10^(-2)Scm^(-1)정도까지 증가하였다. 이러한 전도도의 변화는 화학결합 특성, 공극율 및 단위세포의 크기와 연관지어 이해할 수 있었다. New non-stoichiomtric perovskite oxides Li_(0.33)Sr_(0.34+x)Sc_(x)Nb(1-x)O₃ and Li_(0.33)Sr_(0.34+x-y)Sc_(x)La_(y)-Ta(1-x)O₃ were directly prepared by solid-state thermal reaction. As prepared samples show the simple cubic structure and a small variation of lattice parameter, the vacancy concentraticn and bond character with the composition. The ionic conductivity were determined around 10^(-5) Scm^(-1) near room temperature but increased up to 10^(-2) Scm^(-1) with temperature. The conductivity behavior has been discussed in relation with the variation of chemical bonding, the vacancy concentration and the effective volume of unit-cell of the lattice.
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Bi_(2-x)Pb_(x)Sr₂CaCu₂O_(8) 고온 초전도체의 자속 격자 구조
윤석원,신유주 가톨릭대학교 자연과학연구소 1996 자연과학논문집 Vol.17 No.-
Bi_(2-x)Pb_(x)Sr₂CaCu₂O_(8) 고온 초전도체 단결정을 온도 gradient 방법으로 성장하였다. 4-probe 방법을 이용하여 단결정의 온도에 따른 저항 변화를 측정함으로써 시료의 초전도성을 확인하였다. Bitter 장식법을 이용하여 Pb 농도에 따른 자속 격자 구조의 변화를 정성적으로 관측하고 이를 Pb 불순물의 자속 pinning 효과와 관련지어 논의하였다. Single crystals of Bi_(2-x)Pb_(x)Sr₂CaCu₂O_(8) high temperature superconductors have been grown by the temperature gradient method. Measurements of the temperature dependence of the resistance by 4-probe method have confirmed the superconductivity of the crystals. Bitter decoration technique has been used to observe the changes in the flux-line lattice structures as a function of Pb concentration and the results are discussed in conjunction with the flux-line pinning effects of Pb impurities.
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Plasmid DNA pBR 322의 증폭과 Hydroxyapatite Chromatography에 의한 분리
오두환,유주현,신원철,정건섭,유승구 연세대학교 산업기술연구소 1984 논문집 Vol.16 No.1
The amplification and the isolation conditions of pBR322 plasmid DNA were investigated. For the amplification of pBR322 plasmid DNA, cells from logarithmic growth phase were most effective. The optimal conditions for the amplification of pBR322 plasmid DNA in Escherichia coli GM4 were obtained as follows; 50-150 ㎍/ml of chloramphenicol concentration, 6-8 hours of incubation time in the presence of chloramphenicol. Ampicillin and tetracycline had no effect on the amplification of pBR322 plasmid DNA. Approximately 1 mg of pBR322 plasmid DNA was purified from 3.5 ℓof Escherichia coli GM4 culture broth by hydroxyapatite chromatography. The purified pBR322 plasmid DNA was expressed in Escherichia coli C600.
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홍나영,유혜경,이주현,석혜정,신혜성,김찬주 服飾文化學會 2003 服飾文化硏究 Vol.11 No.3
The main purpose of this exploratory research was to examine the characteristics of consumers who patronize natural-dyed clothes and their perceptions regarding natural-dyed clothes. Thirty three participants who have worn natural-dyed clothes were interviewed for the study. They were asked about styles and price of natural-dyed clothes they owned, their evaluation on them, and the lifestyles of themselves. Existence of subculture among the interviewes and its characteristics were also probed. The results indicated that natural-dyed clothes are relatively high-priced, mostly of modified hanbok style, and became popular in recent years. Interviewees frequently mentioned uniqueness and comfort as the main benefits of natural-dyed clothes, and expressed dissatisfaction regarding color fastness, easy care and problem of coordination. The consumers of natural-dyed clothes appeared to have strong preferences for environment conservation and Korean traditional culture. They also seemed to form a subcultural group who have commonality in their involvement in Korean cultural activities, mainly tea ceremony.
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