• 한국세라믹학회지
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• 제39권3호
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• pp.240-244
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• 2002

$Gd_2O_3,\;CeO_2$ 및 $NH_4Br$ 분말을 사용하여 GdOBr:Ce 형광체를 고상 반응으로 합성하였다. GdOBr:Ce 형광체는 370nm UV 여기 하에 410∼430nm의 영역에서 청색 발광스펙트럼을 보였으며, 2mol%의 Ce 농도에서 최대 발광특성을 나타냈다. FED용 형광체로의 응용 가능성을 알아보기 위해 GdOBr:Ce 형광체의 음극서 발광(CL)을 측정하였다. CL의 경우 PL과 동일한 영역인 410∼430nm에서 발광을 나타냈으며, Ce 농도가 1mol%일 때 발광의 최대치를 보였다. CL에서의 degradation 효과를 보기 위해 전자선을 10분간 조사하여 상용형광체와 비교하였다. 이로부터 GdOBr:Ce 형광체를 FED용 청색 형광체로 응용할 수 있는 가능성을 확인하였다.

• Korean Journal of Radiology
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• 제22권3호
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• pp.354-365
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• 2021

Objective: To investigate the diagnostic performance of contrast-enhanced ultrasound (CEUS) and its role as a second-line imaging modality after gadoxetate-enhanced MRI (Gd-EOB-MRI) in the diagnosis of hepatocellular carcinoma (HCC) among at risk observations. Materials and Methods: We prospectively enrolled participants at risk of HCC with treatment-naïve solid hepatic observations (≥ 1 cm) of Liver Imaging Reporting and Data System (LR)-3/4/5/M during surveillance and performed Gd-EOB-MRI. A total of one hundred and three participants with 103 hepatic observations (mean size, 28.2 ± 24.5 mm; HCCs [n = 79], non-HCC malignancies [n = 15], benign [n = 9]; diagnosed by pathology [n = 57], or noninvasive method [n = 46]) were included in this study. The participants underwent CEUS with sulfur hexafluoride. Arterial phase hyperenhancement (APHE) and washout on Gd-EOB-MRI and CEUS were evaluated. The distinctive washout in CEUS was defined as mild washout 60 seconds after contrast injection. The diagnostic ability of Gd-EOB-MRI and of CEUS as a second-line modality for HCC were determined according to the European Association for the Study of the Liver (EASL) and the Korean Liver Cancer Association and National Cancer Center (KLCA-NCC) guidelines. The diagnostic abilities of both imaging modalities were compared using the McNemar's test. Results: The sensitivity of CEUS (60.8%) was lower than that of Gd-EOB-MRI (72.2%, p = 0.06 by EASL; 86.1%, p < 0.01 by KLCA-NCC); however, the specificity was 100%. By performing CEUS on the inconclusive observations in Gd-EOB-MRI, HCCs without APHE (n = 10) or washout (n = 12) on Gd-EOB-MRI further presented APHE (80.0%, 8/10) or distinctive washout (66.7%, 8/12) on CEUS, and more HCCs were diagnosed than with Gd-EOB-MRI alone (sensitivity: 72.2% vs. 83.5% by EASL, p < 0.01; 86.1% vs. 91.1% by KCLA-NCC, p = 0.04). There were no false-positive cases for HCC on CEUS. Conclusion: The addition of CEUS to Gd-EOB-MRI as a second-line diagnostic modality increases the frequency of HCC diagnosis without changing the specificities.

• 대한화학회지
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• 제47권6호
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• pp.619-624
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• 2003

졸겔법을 사용하여 $Gd_{1.9-x}Li_{0.1}Eu_xO_3$(x=0.02, 0.05, 0.08, 0.12) 형광체 분말을 합성하였다. 형광체 입자의 표면을 나노 크기의 $SiO_2$(입자크기${\thickapprox}30 nm$)로 코팅한 후 스핀-코팅법으로 유리 기판에 형광체 막을 제작하였다. 유리의 연화온도인 $700^{\circ}C$ 부근에서 융착 되는 $SiO_2$ 나노 입자들에 의해 $Gd_{1.9-x}Li_{0.1}Eu_xO_3$ 입자들은 유리 기판 표면 위에 강하게 융착 되었다(>9H, 연필 경도계). 본 연구에서 채택한, 형광체 막을 제조하는 간단하고 비용이 저렴한 이 방법은 디스플레이장치의 응용 분야에 적용될 수 있을 것으로 생각한다.

• 자원리싸이클링
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• 제17권1호
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• pp.12-19
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• 2008

Gd와 Nd이 혼합된 염산용액에서 PC88A와 비누화 PC88A에 의한 용매추출실험을 하였다. 본 연구에서 수행한 실험조건에서 H88A에 의해 Gd이 Nd보다 추출이 잘 되었으며, 40% 비누화된 H88A를 사용하여 Gd와 Nd의 분배계수가 증가하였다. PC88A와 비누화 PC88A에 의한 추출시 초기추출조건으로부터 Gd와 Nd의 분배계수를 예측할 수 있는 모델을 개발하였다. 본 연구에서 개발된 모델을 초기추출조건에 적용하여 예측한 Gd와 Nd의 분배계수는 실험으로 측정한 값과 서로 잘 일치하였다

• Current Applied Physics
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• 제18권12호
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• pp.1523-1527
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• 2018

The thermal stability, magnetic and magnetocaloric properties of $Gd_{55}Co_{35}M_{10}$ (M = Si, Zr and Nb) melts-pun ribbons were studied. The relatively high reduced glass transition temperature ($T_{x1}/T_m$ > 0.60) and low melting point ($T_m$) resulted in excellent glass forming ability (GFA). The Curie temperatures ($T_C$) of melt-spun amorphous ribbons $Gd_{55}Co_{35}M_{10}$ for M = Si, Zr and Nb were 166, 148 and 173 K, respectively. For a magnetic field change of 2 T, the values of maximum magnetic entropy change $(-{\Delta}S_M)^{max}$ for $Gd_{55}Co_{35}Si_{10}$, $Gd_{55}Co_{35}Zr_{10}$ and $Gd_{55}Co_{35}Nb_{10}$ were found to be 2.86, 4.28 and $4.05J\;kg^{-1}K^{-1}$, while the refrigeration capacity (RC) values were 154, 274 and $174J\;kg^{-1}$, respectively. The $RC_{FWHM}$ values of amorphous alloys $Gd_{55}Co_{35}M_{10}$ (M = Si, Zr and Nb) are comparable to or larger than that of $LaFe_{11.6}Si_{1.4}$ crystalline alloy. Large values of $(-{\Delta}S_M)^{max}$ and RC along with good thermal stability make $Gd_{55}Co_{35}M_{10}$ (M = Si, Zr and Nb) amorphous alloys be potential materials for magnetic cooling operating in a wide temperature range from 150 to 175 K, e.g., as part of a gas liquefaction process.

• BMB Reports
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• 제44권7호
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• pp.458-461
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• 2011

Enteropeptidase is a serine protease secreted by the pancreas and converts inactive trypsinogen to active trypsin. Enteropeptidase cleaves the C-terminal end of the substrate recognition sequence Asp-Asp-Asp-Asp-Lys ($D_4K$). The assay for enteropeptidase has utilized $GD_4K$-conjugated 2-naphthylamine ($GD_4K$-NA) as a fluorogenic probe over the last 30 years. However, no other $D_4K$-conjugated fluorogenic substrates of enteropeptidase have been reported. Furthermore, naphthalene is known as carcinogenic to humans. In this study, we used shift in the emission spectrum of $GD_4K$-conjugated 7-amino-4-methylcoumarin ($GD_4K$-AMC) as a fluorogenic method to measure enteropeptidase activity. The kinetic analysis revealed that enteropeptidase has a $K_M$ of 0.025 mM and a $k_{cat}$ of 65 $sec^{-1}$ for $GD_4K$-AMC, whereas it has a $K_M$ of 0.5 to 0.6 mM and a $k_{cat}$ of 25 $sec^{-1}$ for $GD_4K$-NA. The optimum pH of $GD_4K$-AMC hydrolysis was pH 8.0. Our data indicate that $GD_4K$-AMC is more suitable as a substrate for enteropeptidase than $GD_4K$-NA.

• Progress in Superconductivity
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• 제14권1호
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• pp.39-44
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• 2012

The fabrications condition and superconducting properties of top-seeded melt growth (TSMG) processed $GdBa_2Cu_3O_{7-y}$ (Gd123) bulk superconductors were studied. Processing parameters (a maximum temperature ($T_{max}$), a temperature for crystal growth ($T_G$) and a cooling rate ($R_G$) through a peritectic temperature ($T_P$) for the fabrication of single grain Gd123 superconductors were optimized. The magnetic levitation forces, trapped magnetic fields, superconducting transition temperature ($T_c$) and critical current density ($J_c$) of the Gd123 bulks superconductors were estimated. Single grain Gd123 bulk superconductors were successfully fabricated at the optimized processing condition. The $T_c$ of a TSMG processed Gd123 sample was 92.5 K and the $J_c$ at 77 K and 0 T was approximately $50kA/cm^2$. The trapped magnetic field contour and magnetic levitation forces were dependent on the top surface morphology of TSMG processed Gd123 samples. The single grain Gd123 samples, field-cooled at 77 K using a Nd-B-Fe permanent magnet with 5.27 kG and 30 mm dia., showed the trapped magnetic field contour of a single grain with a maximum of 4 kG at the sample center. The maximum magnetic levitation forces of the single grain Gd123 sample, field-cooled or zero field-cooled, were 40 N and 107 N, respectively.

• 한국식품조리과학회지
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• 제23권5호
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• pp.685-695
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• 2007

The purpose of this study was to develop an excellent salad dressing using grape seed oil, which contains high levels of unsaturated fatty acids. First, a vinaigrette was made with grape seed oil and vinegar and divided into five portions. Then, five types of mirepoix au maigre ($M_1,M_2,M_3,M_4,M_5$) were made with apple, onion, carrot, garlic, tomato puree, and tomato ketchup by mixing in a main material vessel. The samples were then allowed to ripen for three days. The control group $M_1$ was named $GD_1$, and the experimental groups $M_2,\;M_3,\;M_4,\;and\;M_5$ were named $GD_2,\;GD_3,\;GD_4,\;and\;GD_5$. respectively. To measure receptiveness, a sensory test was conducted using a 7 point category scale. The test concentrated on flavor, taste, color, agreeability, aftertaste, and overall acceptability: the panel consisted of 15 subjects According to the results, $GD_4$ had the best flavor, color and agreeability. The samples with the most preferred taste and aftertaste were $GD_4\;and\;GD_5$. Between $GD_4\;and\;GD_5$, there were no noticeable differences in taste, aftertaste, or overall acceptability, but differences in color and agreeability did exist. Thus, $GD_4$ proved to be the most favorable product. To determine the best complementing vegetables for $GD_4$ yam($VE_1$), broccoli sprouts($VE_2$), mustard leaves($VE_3$), beet leaves($VE_4$), cucumber($VE_5$), and lettuce(VE6) were selected as samples, and a sensory test was conducted. Each vegetable has its own peculiarities. According to the results, $VE_2$ had the nicest vegetable fragrance recording the highest mean value. The vegetable with the most preferred taste, aftertaste, and agreeability were $VE_2\;and\;VE_6$. $VE_1\;and\;VE_6$ had the nicest color and contained the brightest color as well. The highest overall acceptability was awarded to $VE_2\;and\;VE_6$ and there was no remarkable difference between thorn at a level of 0.05. In conclusion, $VE_2\;and\;VE_6$ were the best complementing vegetables with grape seed oil dressing. However, to commercialize such a dressing, many follow-up studies must be conducted.

• 한국수소및신에너지학회논문집
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• 제30권3호
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• pp.209-219
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• 2019

Methanol is a liquid fuel which could also be produced from renewable energy sources and has appreciably high energy density. In this work, we investigated the application of $Ce_{0.9}Gd_{0.1}O_{2-x}$ supported Cu and Ni catalysts for hydrogen production via methanol steam reforming. Catalysts were synthesized by solution combustion synthesis. The prepared catalysts with various active materials and Cu loading amounts were tested in a reactor at $200-300^{\circ}C$, 0-5 barg range and steam to methanol molar ratio was 1.5. The catalytic properties of Cu and Ni were compared, and the catalytic performance was shown to depend on the amounts of metal loading and operating conditions such as reaction temperature and pressure.

• 한국수소및신에너지학회논문집
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• 제22권2호
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• pp.161-167
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• 2011

Proton conductors have attracted considerable attention for solid oxide fuel cell (SOFC), hydrogen pump, gas sensor, and membrane separators. Doped $SrCeO_3$ exhibits appreciable proton conductivity in hydrogen-containing atmosphere at high temperature. However commercial realization has been hampered due to the reactivity of $SrCeO_3$ with $CO_2$. The chemical stability and proton conductivity are dependent on dopant type. The purpose of this work is to investigate chemical stability of $SrCe_{0.95}Gd_{0.05}O_{3-\alpha}-Ce_{0.9}Gd_{0.1}O_{2-\beta}$ composites in $CO_2$ and $H_2$ gases. Thermogravimetric analysis (TGA) was performed in gaseous $CO_2$ and electrical conductivity of the composites were also measured between 500 and $900^{\circ}C$ in air and $H_2$ atmosphere. $SrCe_{0.95}Gd_{0.05}O_{3-\alpha}-Ce_{0.9}Gd_{0.1}O_{2-\beta}$ composite membranes showed good chemical stability of in $CO_2$ atmosphere and high conductivity at hydrogen condition. The hydrogen permeation of $SrCe_{0.95}Gd_{0.05}O_{3-\alpha}-Ce_{0.9}Gd_{0.1}O_{2-\beta}$ composite membranes was investigated as a function of volumetric content of $SrCe_{0.95}Gd_{0.05}O_{3-\alpha}$. The $SrCe_{0.95}Gd_{0.05}O_{3-\alpha}-Ce_{0.9}Gd_{0.1}O_{2-\beta}$(6:4) membrane with a thickness of 1.0 mm showed the highest hydrogen permeability with the flux reaching of 0.12 $ml/min{\cdot}cm^2$ at $800^{\circ}C$ in 100%$H_2/N_2$ as feed gas.