• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2011년도 추계학술발표대회
• /
• pp.19.2-19.2
• /
• 2011

The $(Sr_{0.75},\;La_{0.25})TiO_3$ (SLTO) ultra-thin films with various thicknesses have been grown on Ti-O terminated $SrTiO_3$(100) substrate using Laser-Molecular Beam Epitaxy (Laser MBE). By monitoring the in-situ specular spot intensity oscillation of reflection high energy electron diffraction (RHEED), we controlled the layer-by-layer film growth. The film structure and topography were verified by atomic force microscopy (AFM) and high resolution thin film x-ray diffraction by the synchrotron x-ray radiation. We have also investigated the electronic band structure using x-ray absorption spectroscopy (XAS). The ultra thin SLTO film exhibits thickness driven metal-insulator transition around 8 unit cell thickness when the film thickness progressively reduced to 2 unit cell. The SLTO thin films with an insulating character showed band splitting in Ti $L_3-L_2$ edge XAS spectrum which is attributed to Ti 3d band splitting. This narrow d band splitting could drive the metal-insulator transition along with Anderson Localization. In optical conductivity, we have found the spectral weight transfer from coherent part to incoherent part when the film thickness was reduced. This result indicates the possibility of enhanced electron correlation in ultra thin films.

• 통합자연과학논문집
• /
• 제8권3호
• /
• pp.192-203
• /
• 2015

In view of the growing medicinal importance of pyrazole and its derivatives, the single crystal X-ray diffraction study was carried out for the potential active 2-Benzyl-3-[3-(4-bromo-phenyl)-1-phenyl-1H-pyrazol-4yl]-4,6-dioxo-5-phenyl-octahydro-pyrrolo[3,4-C]pyrrole-1-carboxylic acid ethyl ester ($C_{37}H_{31}BrN_4O_4$, H2O). In the title compound are two molecules exist in the asymmetric unit. It crystallizes in the monoclinic space group $P{\hat{i}}$ with unit cell dimension $a=13.361(18){\AA}$, $b=13.424(17){\AA}$ and $c=21.649(2){\AA}$ [${\alpha}=80.745(9)^{\circ}$, ${\beta}=79.770(10)^{\circ}$ and ${\gamma}=60.788(6)^{\circ}$]. The pyrazole ring adopts planar conformation. The sum of the bond angles at nitrogen atom of the pyrazole ring indicates the $Sp^2$ hybridized state. The crystal structure is stabilized by intramolecular C-H...O hydrogen bond interaction.

• Radiation Oncology Journal
• /
• 제2권2호
• /
• pp.271-280
• /
• 1984

The peripheral dose, defined as the dose outside therapeutic photon fields, which is responsible for the functional damage of the critical organs, fetus, and radiation. induced carcinogenesis, has been investigated for $^{60}Co\;\gamma$ ray and 10 MV Xray. It was measured by silicon diode controlled by semiautomated water phantom without any shielding or with lead plate of HVL thickness put horizontally or vertically to shield stray radiations. Authors could obtain following results. 1. The peripheral dose was larger than $0.7\%$ of central axis maximum dose even at 20cm distance from field margin. That is clinically significant, so it should be reduced. 2. Even for square fields of 10 MV Xray, radial peripheral dose distribution did not coincide with transverse distribution, because of the position of collimator jaws. 3. Between surface and $d_m$, the peripheral dose distributions show a pattern of the dose distribution of electron beams and the maximum doss was approximately proportional to the length of a side of square field. 4. The peripheral doses depended on radiation quality, field size, distance from field margin and depth in water. Distance from field margin was the most important factor. 5. Except for near surface, the peripheral dose from phantom was approximately equal to that from therapy unit. 6. To reduce the surface dose outside fields, therapist should shield stray radiations from therapy unit by lead plate of at least one HVL for 10 MV X-ray and by bolus equivalent to tissue of 0.5cm thickness for $^{60}Co$. 7. To reduce the dose at depth deeper than $d_m$, it is desirable to shield stray radiations from therapy unit by lead.

• 한국결정학회지
• /
• 제11권4호
• /
• pp.238-240
• /
• 2000

A helminth glutathione S-transfease, 26 kDa isozyme from Clonorchis sinensis was cocrystallized with inhibitors by the hanging-drop method with monomethylether 550 as a precipitant. The crystals, grown in the presence of S-methylglutathione or trans-4-phenyl-3-buten-2-one, suitable for X-ray analysis, belong to the hexagonal space group P6₂(or P6₄), with unit cell parameters a= b= 97.6Å, c=117.4Å. X-ray diffraction data were collected with 2.5Å resolution.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2012년도 추계학술대회 논문집
• /
• pp.965-966
• /
• 2012

• 한국세라믹학회지
• /
• 제25권6호
• /
• pp.577-584
• /
• 1988

Gd1Ba2Cu3O9-x has been found to be a high Tc superconductor with a transitiion onset at 91K and zero resistance achieved at 87K. The structure as determined from x-ray diffraction is orthorhombic, with lattice constants b=3.842$\pm$0.002$\AA$, b=3.895$\pm$0.003$\AA$, and c=11.684$\pm$0.007$\AA$. The structural similarities between the Gd1Ba2Cu3O9-x compound and the well-studied single phase perovskite, Y1Ba2Cu3O9-x are discussed. A correlation between the observed x-ray spectrum and the effect of oxygen deficiencies in several of the unit cell planes is also discussed.

• 한국재료학회지
• /
• 제4권3호
• /
• pp.268-279
• /
• 1994

단일상을 갖는 $Bi_2S_2CaCu_2O_{8+x}$ (2212)의 x-ray 분말 pattern을 a=5.408, c=30.83 $\AA$의 격자상수 및 역격자 벡터 $q^*=0.211b^*-c^*$을 갖는 pseudo tetragonal subcell을 이용하여 모두 index하였다. 임계온도 110K를 갖는 $Bi_2S_2CaCu_2O_{10+x}$ 상은 incommensurate supercell에 속하는 매우 많은 x-ray분말선들을 가지고 있다. Indixing guide로 전자회절사진(electron diffraction photographs)을 이용 x-ray분말 pattern에 대한 지수결정방법을 얻었다.$Bi_2S_2CaCu_2O_{10+x}$(2223)의 단위세표(unit cell)는 기하학적으로 격자상수 a=5.411, b=5.420, c=37.29(2) A을 갖는 orthorhombic subcell이다. Supercell반사 지수들은 subcell의 파 벡터 $\pm q^*=0.211b^*-0.78c^*$을 갖는 k,1지수로부터 영향을 받은 것이다. b 방향으로의 inconnensurate성분 $\delta$는 두 상에 대해 다 같으나, 2212에서 2223 상으로의 변환에 따라 c 방향으로의 초격자성분(superlattic component)은 connensurate($\varepsilon$=1)로부터 incommensurate($\varepsilon$=0.78)로 변한다.

• 한국방사선학회논문지
• /
• 제12권7호
• /
• pp.879-886
• /
• 2018

3-dimensional(D) 프린터는 컴퓨터로 모델링 한 데이터를 바탕으로 3차원의 입체 물체를 출력할 수 있는 장비이다. 이러한 특징을 방사선과학 분야와 융합하여, CT 데이터를 이용한 뼈 모형 X선 팬텀제작 등에 활용되고 있다. 본 연구는 기존의 Pelvis팬텀을 CT 스캔하고 얻어진 데이터로 Fused Filament Fabrication(FFF) 3D 프린터의 소재인 PLA, Wood, XT-CF20, Glow fill, Steel 필라멘트를 이용하여, 뼈 모형 팬텀을 제작하였다. 기존의 Pelvis 팬텀과 3D 프린터로 제작된 5가지 재질의 팬텀을 동일한 조건으로 CT 스캔 하고 얻어진 영상에서 Hounsfield Unit(HU)을 측정하였으며, 진단용X선 발생장치를 이용하여 SI, SNR을 측정하여 각 팬텀을 비교 분석하였다. 그 결과 사지 X선 검사 조건 내에서 X선 팬텀은 glow fill 필라멘트가 가장 적합하다는 것을 알 수 있었다. 본 연구의 기반으로 필라멘트의 특성들을 알 수 있었으며, X선 팬텀 제작에 대한 실용성을 확인하였다.

• 한국진공학회지
• /
• 제11권3호
• /
• pp.166-170
• /
• 2002

$BaTiO_3$(BTO)/$SrTiO_3$(STO) 산화물 인공 초격자가 MgO(100) 단결정 기판위에 Pulsed laser deposition(PLD)법으로 증착되었다. 다층구조에서 BTO/STO 층의 적층 주기는 $BTO_{1\;unit\; cell}/STO_{1\;unit\; cell}$에서 $BTO_{125\;unit\; cell}/STO_{125 \;unit \;cell}$ 두께로 변화시켰고 초격자 전체 두께는 100 m으로 고정시켰다. X-ray 회절 결과는 다양한 주기의 BTO/STO 산화물 박막에서 초격자의 특성을 보였고 투과형 전자 현미경을 통해서 BTO와 STO의 두 층간의 계면에서 상호확산이 일어나지 않고 초격자가 잘 성장된 것을 확인하였다. 초격자의 유전율은 임계 두께 내에서 적층주기가 감소함에 따라 증가하였다. 이러한 초격자의 유전율은 낮은 주기 즉 $BTO_{2\;unit\; cell}/STO_{2\;unit\; cell}$ 주기에서 1230으로 높게 나왔으며 이러한 원인은 격자 변형(c/a ratio)에 기여된 것으로 분석되었다.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제9권2호
• /
• pp.117-123
• /
• 2009

$Pb_{x}Cd_{1-x}S$ films are prepared in the composition range of 0.05${\leq}x{\leq}$0.25, using a chemical bath deposition growth technique under optimum conditions amide at realizing good photo response. The x-ray diffraction results show that the films are of PbS-CdS composite with individual CdS and PbS planes. The films exhibit two direct band gaps, 2.4 eV attributed to CdS, while the other varies continuously from 2.4 eV to 1.3 eV. The films surface morphology is smooth with crystallite, whose grain size increases with increasing mole fraction (x). The decrease in band gap with increase in lead concentration suggests inter-metallic compound of PbS (Eg=0.41 eV) with CdS (Eg=2.4 eV)