• Progress in Superconductivity
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• 제3권2호
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• pp.198-212
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• 2002

The effects of reacted precursors on phase evolution, microstructure, $J_{c}$ and junctional characteristic of the inter-granular contacts were investigated in Ag-sheathed T1-1223 tapes prepared using three kinds of reacted precursors, and compared to those in the tape prepared using an unreacted precursor The precursors were prepared by heat-treating a mixture of Sr-Ba-Ca-Cu-O, $Tl_2$$O_3$, PbO and $Bi_2$$O_3$ powders at $805^{\circ}C$ (precursor I ), $840^{\circ}C$ (precursor II ) and $905^{\circ}C$(precursor III) for 20 min. Tl-1223 phase content, grain size and J\ulcorner in the tapes appeared to increase in an order of precursors I, II and III Compared to tapes prepared using an unreacted precursor, the tapes prewar ed using precursors II and III revealed reduced pore and impurity densities and an enhanced texture. Also characteristic of inter -granular contacts and fraction of strong-links were improved. The improved properties are attributed to enhanced densification resulting from using the reacted precursors.s.

• 대한화학회지
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• 제37권5호
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• pp.503-512
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• 1993

역상 액체 크로마토그래피를 이용하여 페놀류를 효과적으로 분리-분석하는데 기본적으로 필요한 용리거동을 조사하고, 이를 바탕으로 머무름을 예측하는데 이 연구의 목적을 두었다. 정지상으로는 monomeric $C_{18}$ 컬럼($\mu-{Bondapak}$)과 polymeric $C_{18}$ 컬럼(201TP)을 사용하여 상호 비교하였으며, 이동상으로는 메탄올-물과 아세토니트릴-물 혼합액을 사용하고, 대상물질로는 25종의 페놀류를 선택하였다. 엔탈피-엔트로피 상쇄현상을 조사하였을 때 nitrophenols의 머무름은 이동상에 관계없이 methylphenols와 chlorophenols의 머무름과는 달랐으며, 메탄올-물 이동상에서 methylphenols와 chlorophenols는 상쇄현상이 있기 때문에 그 머무름 메카니즘은 조성과 관계없이 일정하였고, 아세토니트릴-물에서는 머무름 메카니즘이 더욱 복잡함을 알았다. Monomeric $C_{18}$ 컬럼과 polymeric $C_{18}$ 컬럼에서의 페놀류의 머무름을 비교하였을 때, polymeric $C_{18}$ 컬럼에서 정지상과 시료의 소수성 상호작용이 더 큼을 알 수 있었다. 메탄올-물 및 아세토니트릴-물 계에서 이동상의 조성 및 컬럼 온도가 변화할 때 쉽게 계산할 수 있는 $\pi$와 ${\sigma}+E_s$ 파라미터를 이용하여 페놀류의 머무름을 예측할 수 있는 관계식을 구하였다.

• 대한두경부종양학회지
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• 제22권2호
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• pp.130-136
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• 2006

Introduction : The sensitivity of tumor cells to radiotherapy is a critical determinant of local control and potential cure in advanced head and neck squamous cell carcinoma(HNSCC). The emergence of radioresistant tumor cells is an obstacle to cancer therapy. Most radioresistant cells have a higher proportion of cells in the Sphase of the cell cycle and a lower apoptotic fraction than radiosensitive cells. HSV replication is increased in cells that have higher S-phase fractions. NV1066 is an oncolytic herpes simplex virus type-1 mutant. We hypothesized that NV1066 replication and cytotoxicity are increased in radioresistant cells. The purpose of this study is to evaluate the antitumor efficacy of NV1066 to treat radioresistant HNSCC. Methods : Radioresistant cells were selected by treating five HNSCC cell lines with repeated conventional fractionated doses of radiation(2Gy/day), using a Cs-137 irradiator, up to a cumulative dose of 70Gy. Clonogenic cell survival and S-phase fractions were compared between radioresistant and parental radiosensitive cells. The two cell populations were then treated with NV1066 to examine viral replication, by the viral plaque assay and viral cytotoxicity. Results : Fractionated irradiation resulted in the selection of radioresistant cells. Radioresistant cells had a higher S-phase fraction(42.9%) compared to parental cells(26.2%). NV1066 replication in radioresistant cells was 7.4 times higher than in parental cells(p<0.01). Treatment with NV1066 resulted in increased cytotoxicity of 24.5% in radioresistant cells compared to parental cells(p<0.05). Conclusion : NV1066 showed increased viral replication and cytotoxicity in radioresistant HNSCC cell lines. These findings suggest a potential clinical application for this oncolytic viral therapy as treatment for radioresistant head and neck cancers.

• Archives of Pharmacal Research
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• 제21권3호
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• pp.298-304
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• 1998

Retinoids are applied to not only cancer prevention but also cancer chemotherapy by stimulating differentiation of cells. We studied differentiation inducing effect of all-trans retinoic acid (ATRA) by studying proportion of high dense fractions of stem-like cells and the size of S phase fraction in cell cycle. From mammary organoids obtained from 7- to 8-week old F344 female rat mammary gland, we cultured rat mammary epithelial cells (RMEC) and treated physiological doses of $10^{-6}$, $10^{-7}$, and $10^{-8}$ M ATRA from the first day and then cultured for 4, 7, and 14 days. After that, immunostaining was performed using peanut agglutinin (PNA) and anti-Thy-1.1 monoclonal antibody (Thy-1.1) that can be used as markers of differentiation. We separated four different cell subpopulations by flow cytometry: cells negative to both reagents (B-), PNA-positive cells (PNA+), Thy-1.1-positive cells (Thy-1.1+), and cells positive to both reagents (B+). We observed continuous decreases of high dense fractions of stem-like cells (PNA+ subpopulations) for 14 days and as much decreases as high doses of ATRA, which were thought to be proportional to doses of ATRA. We labeled RMEC with bromodeoxyuridine and investigated cell cycle fractions that went through S phase. We observed a tendency of decrease of S phase fraction with time in culture, which, is thought to be related to continuous decreases of PNA+ subpopulations and inhibitory role of ATRA on cell cycle. These results suggest that physiological doses of ATRA could stimulate differentiation of RMEC and convert stem-like RMEC to differentiated cells in SFM for a relatively long period of 14 days.

• 한국지하수토양환경학회지:지하수토양환경
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• 제26권5호
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• pp.20-28
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• 2021

Perfluorinated compounds(PFCs), an emerging environmental pollutant, are environmentally persistent and bioaccumulative organic compounds that possess a toxic impact on human health and ecosystems. PFCs are distributed widely in environment media including groundwater, surface water, soil and sediment. PFCs in contaminated solid can potentially leach into groundwater. Therefore, understanding PFCs partitioning between the aqueous phase and solid phase is important for the determination of their fate and transport in the environment. In this study, the sorption equilibrium batch and kinetic experiment of PFCs were carried out to estimated the sorption coefficient(K_d) and the fraction between aqueous-solid phase partition, respectively. Sorption branches of the PFDA(Perfluoro-n-decanoic acid), PFNA(Perfluoro-n-nonanoic acid), PFOA(Perfluoro-n-octanoic acid), PFOS(Perfluoro-1-octane sulfonic acid) and PFHxS(Perfluoro-1-hexane sulfonic acid) isotherms were nearly linear, and the estimated K_d was as follow: PFDA(1.50) > PFOS(1.49) > PFNA(0.81) > PFHxS(0.45) > PFOA(0.39). The sorption kinetics of PFDA, PFNA, PFOA, PFOS and PFHxS onto soil were described by a biexponential adsorption model, suggesting that a fast transport into the surface layer of soil, followed by two-step diffusion transport into the internal water and/or organic matter of soil. Shorter times(<20hr) were required to achieve equilibrium and fraction for adsorption on solid(F₁, F₂) increased with perfluorinated carbon chain length and sulfonate compounds in this study. Overall, our results suggested that not only the perfluorocarbon chain length, but also the terminal functional groups are important contributors to electrostatic and hydrophobic interactions between PFCs and soils, and organic matter in soils significantly affects adsorption maximum capacity than kinetic rate.

• 한국대기환경학회지
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• 제27권2호
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• pp.152-167
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• 2011

MODIS/Terra level 3 and NCEP/NCAR Reanalysis data from 2001 to 2008 have been analyzed to understand long-term aerosol and cloud optical properties, and their relationships around Korea. Interestingly, cloud fraction(CF) has the similar annual variation to aerosol optical depth (${\tau}_a$) without any temporal significant trend. Horizontal distributions of ${\tau}_a$ showed the substantial horizontal gradient from China to Korea, especially with the strong difference over the Yellow Sea, which could represent the evidence of the anthropogenic influence from China in the perspective of long-term average. Specifically the negative correlations between ${\tau}_a$ and liquid-phase cloud effective radius ($r_e$) were shown on the monthly-average basis, only in summer with significant associations over the Yellow Sea, but not in the other seasons and/or specific regions. Relationship between ${\tau}_a$ and CF for the low-level liquid-phase clouds exhibited the overall positive correlation, being consistent with cloud lifetime effect. Meanwhile static stability showed no deterministic relationships with ${\tau}_a$ as well as CF. The dependence of aerosol-cloud relationship on the meteorological conditions should be examined more in detail with the satellite remote sensing and reanalysis data.

• Clinical and Experimental Reproductive Medicine
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• 제9권1_2호
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• pp.43-53
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• 1982

여성의 난소기능은 뇨중 Oestrone-3-glucuronide를 간편한 solid-phase 의 화학발광성 면역학적 측정법 (Chemiluminescence Imrnunoassay(CIA) 에 의하여 그 기능이 탐지될 수 있다. Oestrone-3-g1ucuronyl-6-bovine serum albumine에 대한 antiserum의 IgG fraction은 polystyrene 실험관벽에 흡착시켰으며, 항원으로서는 est r one-3- gl ucuronyI-6-aminoethyl-ethyl-isoluminol 을 항원 (antigen) 에 labeI 시킨 것이다. 시험 대상물인 뇨는 매일아침뇨(early morning urine) 을 희석 (1:1000 V/V)한 후 100mcl 를 취하여 이를 각기 이중분석액으로 택하였다. 시험관 내에서 결합반응 (1 hour at $4^{\circ}C)이 일어난 후에는 시험관내의 액체를 전부 흡입 폐기시켰으며, 항체반응이 일어난 후 ( antibody-bound fraction )에는 완충액 (400mcl)으로 한번 세척시켰다. 그후 염화수산화물(2N , 200mcl)을 가지고 $22^{\circ}C$에 60 분간 방치 혼합케 한 후 효소(microperoxidase) 와 과산화수소를 가하면서 산화작용에서 발생되는 발광양을 10초동안 측정하여 그 결과를 분석하였다. 위에 기술한 분석방법을 평가하면 다음과 같은 결론을 얻었다. Calibration curve sensitivity$3.12{\pm}0.75$ PG/tube ($mean{\pm}SD$)였고, lntra-assay precision(CV%) 9.52 (20 replicates;$38.4{\pm}3.66$nmol/1) 와 8.81 (15 replicates; $102.4{\pm}8.82$nmol/1)였다. Inter-assay precision(CV%) 은 11.9 (mean of 4 pools-7.03, 23.16, 52.11 과 117.53 nmol/1)로 2개월 동안에 걸쳐 시행되었고, 평균 비이어스(mean bias)는 -0.78 로 28에서 448 nmol 범위로서 매일아침 "뇨"의 차이분(different aliquots)은 좋은 결과를 얻었다. 건강한 여성으로부터 채취된 뇨중 Oestrone-3-glucuronide 의 농도(nmol/1)를 보면 월경주기의 여포기와 배난기 및 황체기에 있어서 각기 $40.2{\pm}9.9$ , $102.3{\pm}39.4$와 $84.3{\pm}13.3$nmol/1였다. 이와같은 결과는 동일한 검사뇨를 방사면역학적 방법(RIA)으로 측정 (6 menstrual cycle)한 결과와 유사한 측정치를 얻으므로서 간편하고 진보된 좋은 방법중의 하나라고 사료되는바이다.

• 대한방사선기술학회지:방사선기술과학
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• 제45권2호
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• pp.151-158
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• 2022

The Cardiac Gated Blood Pool (GBP) scintigram, a nuclear medicine imaging, calculates the left ventricular Ejection Fraction (EF) by segmenting the left ventricle from the heart. However, in order to accurately segment the substructure of the heart, specialized knowledge of cardiac anatomy is required, and depending on the expert's processing, there may be a problem in which the left ventricular EF is calculated differently. In this study, using the DeepLabV3 architecture, GBP images were trained on 93 training data with a ResNet-50 backbone. Afterwards, the trained model was applied to 23 separate test sets of GBP to evaluate the reproducibility of the region of interest and left ventricular EF. Pixel accuracy, dice coefficient, and IoU for the region of interest were 99.32±0.20, 94.65±1.45, 89.89±2.62(%) at the diastolic phase, and 99.26±0.34, 90.16±4.19, and 82.33±6.69(%) at the systolic phase, respectively. Left ventricular EF was calculated to be an average of 60.37±7.32% in the ROI set by humans and 58.68±7.22% in the ROI set by the deep learning segmentation model. (p<0.05) The automated segmentation method using deep learning presented in this study similarly predicts the average human-set ROI and left ventricular EF when a random GBP image is an input. If the automatic segmentation method is developed and applied to the functional examination method that needs to set ROI in the field of cardiac scintigram in nuclear medicine in the future, it is expected to greatly contribute to improving the efficiency and accuracy of processing and analysis by nuclear medicine specialists.

• 생약학회지
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• 제17권4호
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• pp.286-291
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• 1986

Forty herbal drugs which are described to have potential antitumor activity were solvent-fractionated with petroleum ether, ether and ethyl acetate in sequence. The cytotoxic activity was mostly shown in the ether fraction(40.54%) and petroleum ether fraction (35.15%), but scarcely in the water phase (10.8%), meaning that most of the active components had less polar property. Twenty-seven percent of the drugs tested were active, which is higher value than 10.4% of the random sampled drugs The drugs possessing the $ED_{50}$ values less than $10{mu}g/ml$ were the roots of Lithospermum erythrorhizon, Curcuma domestica, Salvia miltiorrhiza, Astragalus membraneceus and Scutellaria indica, the leaves of Panax ginseng, S. indica and Liriodendron tulipifera, the barks of Picrasma ailanthoides and Rhus vernifera, the herbs of Agrimonia pilosa and Siegesbeckia pubescens the seeds of Tricosanthes kirilowii, P. ailanthoides, and the stem of P. ginseng.

• 한국전산유체공학회지
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• 제20권4호
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• pp.1-6
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• 2015

Centrifugal pumps consume considerable amount of energy in various industrial applications. Therefore, improvement of the efficiency of these machines has become a major challenge. Cavitation is a phenomenon which decreases the pump efficiency and even causes structural demage. Hence, the goal of this paper is to investigate the cavitation problem in the single-stage and double-stage centrifugal pumps. The Volume of Fraction (VOF) method has been used for the numerical simulations together with Rayliegh-Plesset model for the gas-liquid two-phase flow inside the pump. In order to capture the turbulent phenomena, the standard k-${\varepsilon}$ turbulence model has been adopted, and the simulations have been done as unsteady cases. In addition, the motion of the rotating parts has been simulated using Multi Reference Frame(MRF) method. The results are presented and compared in terms of hydraulic head and NPSH for both the single-stage and double-stage pumps. The H-Q curves show the effects of cavitation on decreasing the pumps performances.