• Progress in Superconductivity
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• 제1권2호
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• pp.135-140
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• 2000

Distribution of Pr ions between Y- and Ba-site of the $Y(Ba_{1-Xn}Pr_{Xn})_2Cu_3O_y$ ($0{\leq}Xn{\leq}{0.3}$, Xn : nominal composition) material prepared by the solid state reaction method was studied. Although the samples have narrow superconducting transition, tiny peaks of $Y_2BaCuO_5$ impurity phase are included in the x-ray diffraction patterns suggesting that some of the Pr ions are entered into the Y-site. The distribution of Pr ions between Y- and Ba-site was determined by measuring the mass fraction of YBCO and $Y_2BaCuO_5$ phase for each sample through the Rietveld analysis of the x-ray diffraction data. About 60 % of Pr ions occupy the Y-site regardless of the Pr content. Various superconducting parameters such as the oxygen content and the hole concentration etc. are compared before and after the impurity correction.

• 대한전자공학회논문지
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• 제22권4호
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• pp.51-58
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• 1985

Ion-implanted E-IGFET의 도핑 profile을 임의로 가정하여 threshold 전압을 구하였고. short-channoel에 적용할 때 correction factor K의 개념을 사용하였다. Threshold전압의 이론치는 실험치와 잘 일치하였고, 또한 I-V특성도 실험치와 잘 일치하였다. 아울러 이 program을 package화 하여 실용화시켰다.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
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• pp.171-174
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• 1999

We have characterized solid solution Y$_{l-x}Ca_xBa_2Cu_3O_y$ (0${\le}$x${\le}$0.3) materials by measuring the XRD pattern, resistivity and hole concentrations, etc. As Ca concentration increases, T$_c$, is decreased monotonically because the hole concentration on the superconducting plane increases beyond the optimum region in the electronic phase diagram due to the hole transfer from the Cu-O chain to the CuO$_2$ plane. A very small amount of secondary phase have large effects on the analysis of oxygen content and hole concentration etc. The results before the correction of impurity phase are compared with those after the correction.

• Nuclear Engineering and Technology
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• 제21권1호
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• pp.12-17
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• 1989

용액 순환형 황산망간 용액조 장치를 이용한 중성자 방출류의 절대측정을 위해서 황산망간 용액이 채워진 용액조 안에서 $^{55}$Mn에 의해 흡수되는 중성자 분율에 대한 보정인자를 결정하였다. 이 보정인자, 1/f은 망간, 유황 및 용액에 함유된 불순물 원소들의 원자수 밀도와 유효중성자 포획단면적을 이용하여 결정되었다. 각 원소들의 원자수 밀도의 결정을 위한 용액의 농도는 EDTA 적정에 의한 용량법과 중량법에 의해 분석하였고 불순물 함량은 ICP 방법을 이용하였다. 한편, 유효 중성자 포획 단면적은 자체 작성한 FORTRAN Program EASCAL, Westcotte의 매개변수 및 Axton의 실험식을 사용하여 계산하였다.

• 분석과학
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• 제23권5호
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• pp.498-504
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• 2010

열 이온화 질량분석을 이용한 루테늄(Ru) 동위원소 비 측정은 루테늄의 이온화 포텐셜이 높고 산화상태로 휘발이 일어나 시료가 쉽게 소모되어 안정된 이온피크를 얻기가 어렵다. 따라서 이온화 효율을 높이고 안정적 이온생성을 위한 실험과 질량분석에 사용되는 레늄(Re) 필라멘트에 함유된 불순물들에 의한 동중원소 영향을 검토하였다. 질량분석에서 double filament를 사용하는 것 보다는 single filament를 사용하는 것이 더 안정적 이온 피크를 얻을 수 있었을 뿐만 아니라 몰리브데넘(Mo)에 의한 동중원소 영향도 작았다. 또한 필라멘트 온도를 필요이상 높이면 높일수록 동중원소 영향이 큼을 알 수 있었다. 즉, 불순물로 함유된 Mo이 Ru 동위원소 비 측정에 큰 영향을 주었다. 특히 필라멘트 온도를 일정한 시간 간격을 두고 서서히 올려주는 것이 안정된 피크를 얻는데 매우 중요함을 알 수 있었다. Mo으로부터 오는 동중원소 영향을 $^{94}Mo/^{99}Ru$ 비를 측정하여 보정함으로써 Ru 동위원소 비를 정확히 측정할 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.185.2-185.2
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• 2014

We have studied the atomic and electronic structure of graphene nanoribbons (GNRs) on a hexagonal boron nitride (h-BN) sheet with intercalated atoms using first-principles calculations. The h-BN sheet is an insulator with the band gap about 6 eV and then it may a good candidate as a supporting dielectric substrate for graphene-based nanodevices. Especially, the h-BN sheet has the similar bond structure as graphene with a slightly longer lattice constant. For the computation, we use the Vienna ab initio simulation package (VASP). The generalized gradient approximation (GGA) in the form of the PBE-type parameterization is employed. The ions are described via the projector augmented wave potentials, and the cutoff energy for the plane-wave basis is set to 400 eV. To include weak van der Waals (vdW) interactions, we adopt the Grimme's DFT-D2 vdW correction based on a semi-empirical GGA-type theory. Our calculations reveal that the localized states appear at the zigzag edge of the GNR on the h-BN sheet due to the flat band of the zigzag edge at the Fermi level and the localized states rapidly decay into the bulk. The open-edged graphene with a large corrugation allows some space between graphene and h-BN sheet. Therefore, atoms or molecules can be intercalated between them. We have considered various types of atoms for intercalation. The atoms are initially placed at the edge of the GNR or inserted in between GNR and h-BN sheet to find the effect of intercalated atoms on the atomic and electronic structure of graphene. We find that the impurity atoms at the edge of GNR are more stable than in between GNR and h-BN sheet for all cases considered. The nickel atom has the lowest energy difference of ~0.2 eV, which means that it is relatively easy to intercalate the Ni atom in this structure. Finally, the magnetic properties of intercalated atoms between GNR and h-BN sheet are investigated.

• 대한방사성의약품학회지
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• 제7권2호
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• pp.119-125
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• 2021

⁸²Sr for ⁸²Rb generator was produced through the irradiation of the proton beam on the ^nat.RbCI target at the target irradiation facility installed at the end of the Rl-dedicated beamline of the 100 MeV proton linear accelerator of KOMAC (Korea Multi-purpose Accelerator Complex). The average current of the proton beam was 1.2 µA for irradiation time of 150 min. For the separation and purification of the ⁸²Sr from ^nat.RbCI irradiated, Chelex-100 resin was used. The activities of ⁸²Sr in the irradiated ^nat.RbCI target solution and after purification were 45.29 µCi and 43.4 µCi, respectively. The separation and purification yield was 95.8%. As an adsorbent to be filled in the generator for ⁸²Sr adsorption hydrous tin oxide was selected. The adsorption yield of ⁸²Sr into the generator adsorbent was > 99 %, and the total amount of ⁸²Sr adsorbed to the generator was 21.6 µCi as of the day of the ⁸²Rb elution experiment. When the elution amount was 22 mL, the maximum⁸²Rb elution yield was 93.3%, and the elution yield increased as the flow rate increased. After the eluted ⁸²Rb was filled in the correction phantom of the small PET for animals, a PET image was taken. The image scan time was set to 5 min, and the phantom PET image was successfully obtained. As results of impurity analysis on eluted ⁸²Rb using ICP-MS, ^nat.Rb stable isotopes that compete in vivo of ⁸²Rb were identified as undetected levels and were determined to be No-Carrier-Added (NCA).