• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.1024-1029
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• 2022

Composite scintillation screens on a base of Gd_1.2Y_1.8Ga_2.5Al_2.5O₁₂:Ce (GYAGG) scintillator have been evaluated for neutron detection. Besides the powdered scintillator, the composite includes ⁶LiF particles; both are merged with a binder and deposited onto the light-reflecting aluminum substrate. Results obtained demonstrates that screens are suitable for use with a silicon photomultiplier readout to create a prospective solution for a compact and low-cost thermal neutron sensor. Composite GYAGG/⁶LiF scintillation screen shows a pretty matched sensitivity and γ-background rejection with a widely used ZnS/⁶LiF screens however, possesses forty times faster response.

• Journal of the Korean Ceramic Society
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• v.44 no.12
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• pp.710-714
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• 2007

LSGM$(La_{0.8}Sr_{0.2}Ga_{0.8}Mg_{0.2}O_{3-{\delta}})$ is the very promising electrolyte material for lower-temperature operation of SOFCs, especially when realized in anode-supported cells. But it is notorious for reacting with other cell components and resulting in the highly resistive reaction phases detrimental to cell performance. LDC$(La_{0.4}Ce_{0.6}O_{1.8})$, which is known to keep the interfacial stability between LSGM electrolyte and anode, was adopted in the anode-supported cell, and its effect on the interfacial reactivity and electrochemical performance of the cell was investigated. No severe interfacial reaction and corresponding resistive secondary phase was found in the cell with LDC buffer layer, and this is due to its ability to sustain the La chemical potential in LSGM. The cell exhibited the open circuit voltage of 0.64V, the maximum power density of 223 $mW/cm^2$, and the ohmic resistance of $0.17{\Omega}cm^2$ at $700^{\circ}C$. These values were much improved compared with those from the cell without any buffer layer, which implies that formation of the resistive reaction phases in LSGM and then deterioration of the cell performance is resulted mainly from the La diffusion from LSGM electrolyte to anode.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.1841-1843
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• 2005

냉간 압연과 열처리 공정을 통해 2축 배향성을 가지는 금속 기판 위에 산화물 박막을 중착 시켜 같은 정도의 2축 배향성을 갖도록 제조된 RABiTS template 위에 YBCO 초전도체를 PLD 방법으로 증착하여 YBCO coated conductor 선재를 제조하였다. RABiTS template은 $NiW/Y_2O_3/YSZ/CeO_2$ 구조로 DC reactive sputtering와 PLD 방법에 의해 증착되었다. 모든 공정은 reel-to-reel 방식의 연속 공정으로 이루어졌다. 1m와 10m급의 장선 고온초전도선재를 제조하고, 이에 대한 전기적 특성과 초전도 및 다층 산화물 완충층에 대한 결정성, 표면 특성에 대한 분석을 수행하였다. 그 결과 1m 길이에서 end-to-end 107A와 10.6m 길이에서 end-to-end 51A의 임계 전류를 획득하였다. 제조된 박막형 선재의 초전도 층과 다층의 산화물 완충층 모두 금속 기판의 결정성을 그대로 유지하면서, epitaxial하게 성장하였으며, 최종 YBCO의 in-plane FWHM 값은 > $9^{\circ}$를 유지하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.50-51
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• 2005

냉간 압연과 열처리 공정을 통해 2축 배향성을 가지는 금속 기판 위에 산화물 박막을 증착 시켜 같은 정도의 2축 배향성을 갖도록 제조된 RABiTS template 위에 YBCO 초전도체를 PLD 방법으로 증착하여 YBCO coated conductor 선재를 제조하였다. RABiTS template은 NiW/$Y_2O_3$/NSZ/$CeO_2$ 구조로 DC reactive sputtering와 PLD 방법에 의해 증착되었다. 모든 공정은 reel-to-reel 방식의 연속 공정으로 이루어졌다. 1m와 10m급의 장선 고온초전도선재를 제조하고, 이에 대한 전기적 특성과 초전도 및 다층 산화물 완충층에 대한 결정성, 표면 특성에 대한 분석을 수행하였다. 그 결과 1m 길이에서 end-to-end 107 A와 10.6m 길이에서 end-to-end 51A의 임계 전류를 획득하였다. 제조된 박막형 선재의 초전도 층과 다층의 산화물 완충층 모두 금속 기판의 결정성을 그대로 유지하면서, epitaxial하게 성장하였으며, 최종 YBCO의 in-plane FWHM 값은 > $9^{\circ}$를 유지 하였다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.11
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• pp.1487-1492
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• 2012

Antioxidant activity and neuroprotective effects of extracts from Cichorium endivia L. (CEL) on hydrogen peroxide-induced oxidative damage in neuronal cells were investigated. The total polyphenol and flavonoid contents of the water and ethanolic extracts from CEL were $36.2{\pm}0.99$, $37.2{\pm}3.76$ mg gallic acid equivalent/g extract, and $46.9{\pm}5.22$, $53.86{\pm}5.09$ mg catechin equivalent/g extract, respectively. In addition, antioxidant activities of the extracts were also determined by ferric reducing antioxidant power (FRAP), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and reducing power. In an MTT assay on the neuronal cells, the extracts showed a protective effect by increasing cell viability on hydrogen peroxide-induced oxidative damage in neuronal cells. Antioxidative enzyme (superoxide dismutase: SOD, catalase: CAT) levels in cultured neuronal cells were increased in the presence of extracts from CEL. It was found that CEL extracts inhibited hydrogen peroxide-induced Bcl-2 and Bax expression in neuronal cells. These results indicate that the CEL extracts possess an antioxidant activity.

• Clinical and Experimental Reproductive Medicine
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• v.16 no.2
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• pp.139-146
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• 1989

The purpose of this study was to examine the qualitative variation of human fetal-cord sera (HCS) and to accept the sera in human lVF-ET program. One hundred and sixteenth RCS were tested with 1772 2-cell embryos of F1 (C57BL x CBA) virgin mice, Ten to sixteenth embryos were cultured in m-KRB medium with a aliquot of each serum (10%, v/v) or with bovine serum albumin(O.4%, w/v) as a control medium. Embryonic development were recorded at every 24hr for 4 days by such events as cellular compaction, cavitation, and hatching. In the control groups of eight assays, 98.1%(106/ 108) of 2-ce1l embryos developed above expanded blastocyst and the embryonic development was unified through the tests. But the developmental pattern in medium with each serum was various. Namely, the sera that supported development of 100% 2-cell embryos to above morula, early blastocyst, expanded blastocyst and hatching blastocyst was 45,7%(53/116) , 35.3%(41/116), 15.5%08/116.) and 6.9-%(8/116), respectively. And the sera that supported development of above 80% 2-cell embryos to the each embryonic stage was 92.2% (107/116), 83.6%(97/116), 63.8%(74/116) and 36.2%(42/116), respectively. Meanwhile two kinds of toxic pattern to the embryonic development were observed in some sera. The first pattern is that some sera arrested development of most embryos in pre- or post-stage of morula or blastocyst. The second pattern is that some sera promoted or arrested a part of embryos in the same dish. The ability of serum was depended on the batch of serum. Finally we could accept 69%(80/116) of the tested sera for human IVF-ET program. The base line for acceptance was the ability that supported above 80% 2-ce1l embryos to blastocyst. But some deterious sera were contained in this range. We cut off about 10% of the sera (83.6% , 97/116) that passed the baseline. This final percent of sera was similar to that of grade N of this study.

• Journal of the Korean Vacuum Society
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• v.5 no.4
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• pp.315-326
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• 1996

The electronic structures of 3d and 4d core-levels of rare-earth atoms in the insulating rare-earth (Sm, Eu, Gd, and Tb) compounds were studied with x-ray photoelectron spectroscopy(XPS). It is shown that the intrinsic satellite structure due to the hybridization disappears for chemically stable-earth trivalent heavy rare-earth insulating compounds as the hybridization between f electrons of rare-earth atoms and p electrons of anion atoms decreases due to the lanthanide contraction. Eu atoms at the surface of the stable insulating trivalent Eu compounds are found to be divalent. The satellite peak of Eu 3d core-level spectra at about 10eV higher binding energy side relative the main peak comes from the multiplet structures of $\underline{3d}4f^6$ configuration. The satellite structure appearing at about 15 eV higher binding energy side relative to the main peak in all insulating rare-earth compounds is due to an energy loss process of creating a plasmon.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.6
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• pp.701-717
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• 2003

The objective of this study was to extensively estimate the air quality trends of the study area by surveying con-centration trends in months or seasons, after analyzing the mass concentration of PM-10 samples and the inorganic lements, ion, and total carbon in PM-10. Also, the study introduced to apply the PMF (Positive Matrix Factoriza-tion) model that is useful when absence of the source profile. Thus the model was thought to be suitable in Korea that often has few information about pollution sources. After obtaining results from the PMF modeling, the existing sources at the study area were qualitatively identified The PM-10 particles collected on quartz fiber filters by a PM-10 high-vol air sampler for 3 years (Mar. 1999∼Dec.2001) in Kyung Hee University. The 25 chemical species (Al, Mn, Ti, V, Cr, Fe, Ni, Cu, Zn, As, Se, Cd, Ba, Ce, Pb, Si, N $a^{#}$, N $H_4$$^{+}$, $K^{+}$, $Mg^{2+}$, $Ca^{2+}$, C $l^{[-10]}$ , N $O_3$$^{[-10]}$ , S $O_4$$^{2-}$, TC) were analyzed by ICP-AES, IC, and EA after executing proper pre - treatments of each sample filter. The PMF model was intensively applied to estimate the quantitative contribution of air pollution sources based on the chemical information (128 samples and 25 chemical species). Through a case study of the PMF modeling for the PM-10 aerosols. the total of 11 factors were determined. The multiple linear regression analysis between the observed PM-10 mass concentration and the estimated G matrix had been performed following the FPEAK test. Finally the regression analysis provided source profiles (scaled F matrix). So, 11 sources were qualitatively identified, such as secondary aerosol related source, soil related source, waste incineration source, field burning source, fossil fuel combustion source, industry related source, motor vehicle source, oil/coal combustion source, non-ferrous metal source, and aged sea- salt source, respectively.ively.y.

• Korean Chemical Engineering Research
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• v.60 no.1
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• pp.70-79
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• 2022

Biodiesel production has attracted attention as a sustainable source of fuel and is a competitive alternate to diesel engines. The glycerol that is produced as a by-product is generally discarded as waste and can be converted to green chemicals such as acetins to increase bio-diesel profitability. Acetins find application in fuel, food, pharmaceutical and leather industries. Batch experiments and analysis have been previously conducted for synthesis of acetins using glycerol esterification reaction aided by sulfated metal oxide catalysts (SO₄^2-/CeO₂-ZrO₂). The aim of this study was to optimize process parameters: effects of mole ratio of reactants (glycerol and acetic acid), catalyst concentration and reaction temperature to maximize glycerol conversion/acetin selectivity. The optimum conditions for this reaction were determined using response surface methodology (RSM) designed as per a five-level-three-factor central composite design (CCD). Statistica software 10 was used to analyze the experimental data obtained. The optimized conditions obtained were molar ratio - 1:12, catalyst concentration - 6 wt.% and temperature -90 ℃. A packed bed reactor was fabricated and column studies were performed using the optimized conditions. The breakthrough curve was analyzed.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.135-137
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• 2002

In the favor of adjusting microwave signal, Hairpin type Filter, which delay microwave signal enough to several nanosecond, is a key component. One of the main advantage in using Hairpin type Filter is a conveniency for equipping with Delay Module, and because of having a wide bandwidth, Hairpin type Filter can be designed to satisfy the most applications. In this work, we attempted to estimate the delay time in a superconductive hairpin type filter A software to synthesize even and odd order equiripple hairpin type filter has been developed. This software arbitrarily locate its transfer zeros making symmetric of asymmetric amplitude response and equalizing group delay. Borland C++ compiler has been used. The program was designed to run under MS-DOS, Window 98, Window 2000. The program optimizes the position of the transfer function zeros in order to fulfill the group delay specification masks. We designed and fabricated a hairpin type HTS 2-pole microstrip bandpass filter to operate at 5.8Ghz. The fabrication method was pulsed laser deposition and YBCO films were deposited on sapphire substrates with a Ce$O_{2}$ thin layer as a buffer layer. We also developed a new style hairpin type filter by using interdigitide inner-pole. Compared to the same size regular hairpin type filters, our filters had a lower center frequency.