• Nano
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• 제13권10호
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• pp.1850119.1-1850119.6
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• 2018

$Eu^{3+}/Tb^{3+}$ co-doped nanocomposite containing $CeO_2$ nanocrystals was successfully prepared by an in situ sol-gel polymerization approach. High-resolution transmission electron microscopy demonstrated the homogeneous precipitation of $CeO_2$ nanocrystals among the polymethylmethacrylate (PMMA) matrix. The thermal stability and UV-shielding capability of the obtained nanocomposite were improved with increase of $CeO_2$ content. The tuning of the emissive color from green and yellow to red can be easily achieved by varying the dopant species and concentration. These results suggested that the obtained nanocomposite could be potentially applicable in transparent solid-state luminescent devices.

• Current Applied Physics
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• 제18권12호
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• pp.1546-1552
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• 2018

The polymer nanocomposite as a gate dielectric film was prepared via sol-gel method. The formation of crosslinked structure among nanofillers and polymer matrix was proved by Fourier transform infrared spectroscopy (FT-IR). Differential thermal analysis (DTA) results showed significant increase in the thermal stability of the nanocomposite with respect to that of pure polymer. The nanocomposite films deposited on the p- and n-type Si substrates formed very smooth surface with rms roughness of 0.045 and 0.058 nm respectively. Deconvoluted $Si_{2s}$ spectra revealed the domination of the Si-OH hydrogen bonds and Si-O-Si covalence bonds in the structure of the nanocomposite film deposited on the p- and n-type Si semiconductor layers respectively. The fabricated n-channel field-effect-transistor (FET) showed the low threshold voltage and leakage currents because of the stronger connection between the nanocomposite and n-type Si substrate. Whereas, dominated hydroxyl groups in the nanocomposite dielectric film deposited on the p-type Si substrate increased trap states in the interface, led to the drop of FET operation.

• Korean Journal of Chemical Engineering
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• 제35권11호
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• pp.2191-2197
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• 2018

To remove tar and produce environment-friendly $H_2$, one of the promising routes is the sorption-enhanced steam reforming (SESR) process, in which the $CO_2$ sorbent is a key element. We prepared the $CO_2$ sorbents with $Ca_{12}Al_{14}O_{33}$ as carrier with various methods. Their characterizations were examined, and the sample prepared by solgel (SG) method showed the strongest CaO and $Ca_{12}Al_{14}O_{33}$ phases and the most excellent pore structure among all the samples. Then, a thermogravimetric experiment was conducted, and the results showed that the sample prepared by sol-gel (SG) method had the best $CO_2$ adsorption capacity and excellent long-term cyclic stability. Finally, the sorbent was used into the steam reforming experiments of tar. Under the action of the sorbent, the reforming reaction was enhanced in-situ, with the $H_2$ yield and concentration improved obviously, and especially, $H_2$ concentration can reach over 98.85%.

• 대한안전경영과학회지
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• 제26권1호
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• pp.39-44
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• 2024

In order to prevent accidents via defective ammunition, this paper analyzes recent research on ammunition life prediction methodology. This workanalyzes current shelf-life prediction approaches by comparing the pros and cons of physical modeling, accelerated testing, and statistical analysis-based prediction techniques. Physical modeling-based prediction demonstrates its usefulness in understanding the physical properties and interactions of ammunition. Accelerated testing-based prediction is useful in quickly verifying the reliability and safety of ammunition. Additionally, statistical analysis-based prediction is emphasized for its ability to make decisions based on data. This paper aims to contribute to the early detection of defective ammunition by analyzing ammunition life prediction methodology hereby reducing defective ammunition accidents. In order to prepare not only Korean domestic war situation but also the international affairs from Eastern Europe and Mid East countries, it is very important to enhance the stability of organizations using ammunition and reduce costs of potential accidents.

• Journal of Animal Science and Technology
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• 제52권5호
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• pp.413-426
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• 2010

본 연구는 반추가축에 급여되는 사료원 중 종류별, 수준별 lignosulfonate 처리 대두박의 반추위 내 undegradable protein (UDP) 효율을 알아보기 위하여 실험 I 에서 전체 4종의 lignosulfonate (Desulfonated, Na, Ca, Solution)를 각각 수준별 (2, 4, 8%)로 처리하여 전체 12종의 lignosulfoanted soybeanmeal (LSBM)에 대한 반추위 내 미생물 발효 특성의 미치는 영향을 알아보기 위해 in vitro 시험이 실시되었다. 실험 H에서는 실험 I 에서 대두박의 단백질 보호 효과가 가장 높은 LSBM Na 2% 처리구와 LSBM Solution (LSBM Sol) 2% 처리구 그리고 열처리 LSBM (LSBM Heat) 2%를 이용하여 rumen simulation continuous culture (RSCC) system을 이용한 반추위 내 미생물 발효 특성에 대한 연구가 실시되었다. 시험 I in vitro 시험에서 모든 LSBM 처리구에서 전체 배양시간 평균 pH수준, gas 생성량, $NH_3$-N 농도, 건물소화율, VFA 생성량 그리고 ADF 소화율은 배양시간이 지남에 따라 대조구에 비해 낮은 결과를 나타내었다(p<0.05). 반추위 내 미생물단백질 합성량은 대조구가 LSMB 처리구 보다 통계적으로 높은 결과를 나타내었으며 (p<0.05), LSBM 수준이 증가할수록 반추위 내 미생물 단백질 합성량은 감소하는 경향을 나타내었다. UDP 함량은 대조구보다 LSBM 처리구에서 높은 결과를 나타내었으며(p<0.05), 특히 LSBM Sol 처리구는 대조구에 비해 각각 2%, 4% 그리고 8% 처리군에서 11.18%, 11.54% 그리고 29.11%의 UDP 함량이 증가 하였다. 시험 II는 RSCC system을 이용하여 반추위 내 미생물 발효특성에 대한 시험이 실시되었다. 시험사료는 대조구와 In vitro 시험 중 대조구와 UDP 효과가 높은 LSBM Na 2%, LSBM Sol 2% 그리고 LSBM Heat 2% 처리한 사료 4처리 4반복($4{\times}4$ Latin squire)에 의해 15일간 시험이 실시되었으며, 배양 마지막 3일 동안의 sample을 이용하여 분석을 실시하였다. 전체 배양 기간 중 모든 처리구에서 적응기간 동안 불규칙적인 반추위 미생물 발효 특성을 보였으나 배양 12일 이후 안정된 발효특성을 나타내었다. Sampling 기간 동안의 각 처리간의 평균 pH는 모든 LSBM 처리구에서 대조구보다 높았다(p<0.05). $NH_3$-N 함량, VFA 함량 그리고 반추위 내 미생물 단백질 합성량은 LSBM 처리구가 대조구에 비해 낮은 결과를 나타내었다(p<0.05). UDP 함량은 대조구, LSBM Heat 2%, LSBM Na 2% 그리고 LSBM Sol 2%에서 각 41.55, 43.49, 45.28 그리고 43.52%로 모든 LSBM 처리구가 대조구에 비해 유의하게 높은 경향을 나타내였다(p<0.05). 시험 I과 시험II에서 UDP 함량은 LSBM 처리구에서 lignosulfonate 처리 수준이 증가할수록 증가하는 경향을 나타내었고, 모든 LSBM 처리구는 대조구에 비해 높은 UDP 함량을 나타내었다. 이와 같은 결과는 사료원으로써 대두박에 대한 lignosulfonate 처리가 coating 작용과 열처리에 의한 물리 화학적 효과로 인하여 대두박의 단백질 분해율을 저해 시킨 것으로 사료된다. 그러나 LSBM 처리군 중 건물소화율과 반추위 내 미생물단백질 합성량은 LSBM 2% 처리구에서 가장 높은 결과를 나타내였다. 따라서, 반추가축 사료내 LSBM 첨가가 In vitro와 RSCC system을 이용한 반추위내 미생물발효 특성 시험에서 반추위 내에서 by-pass protein 함량을 증가시키는 결과를 나타내었으며, 추후 착유우를 이용한 LSBM 급여를 시험을 통하여 유단백질 증진효과에 대하여 추가적인 평가가 이루어져야 할 것으로 사료된다.

• Journal of Acupuncture Research
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• 제32권3호
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• pp.127-133
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• 2015

Objectives : Previous studies have shown that the amount of melittin, the main active ingredient in bee venom pharmacopuncture, tends to decrease substantially with time during pharmacopuncture manufacture. This study aimed to assess whether the stability of bee venom pharmacopuncture improved with pharmacopuncture additives. Methods : Components were measured using high performance liquid chromatography. Acute toxicity and antigenicity tests by subcutaneous and venous routes were conducted at Korea Pharmaceutical Test & Research Institute and mortality, adverse reactions, and body weight changes were assessed. Results : Stability tests using additives revealed that bee venom without additives was most stable. Bee venom pharmacopuncture without additives was further tested for toxicity in subcutaneous and venous administration in mice and no changes pertaining to toxicity were found over the testing period. Conclusions : Bee venom pharmacopuncture without additives was found to be most stable, and further, it did not show toxicity or antigenicity in subcutaneous and venous administration in mice.

• 멤브레인
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• 제20권4호
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• pp.278-289
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• 2010

술폰화 폴리아릴렌에테르술폰(SPAES) 고분자 전해질막은 상온($25^{\circ}C$, 100%RH)에서 우수한 수소이온전도도를 나타내는 반면 고온-저가습($120^{\circ}C$, 48%RH) 조건에서 나피온212 보다 낮은 수소이온전도도 값을 나타낸다. 이러한 단점을 극복하기 위해 수분 보유능력이 뛰어난 tetraethyl orthosilicate (TEOS)를 50, 100, 150, 200% 포함하는 SPAES 복합막을 제조하고 각각의 특성을 고찰하였다. FT-IR 및 TEM을 이용한 분석 결과 복합막 내에서 TEOS가 축합반응을 통하여 Si-O-Si 형태로 연결되었음을 확인하였으나, 입자 형태가 성장되지 않고 oligomer 형태로 이루어져 있음을 확인하였다. 또한 이러한 silicon dioxide 화합물이 복합막 내에서 균일하게 잘 분산되어 있음을 EDS 분석을 통해 확인하였다. TEOS를 함유한 복합막의 경우, TEOS의 수분 유지능력에 의해 높은 온도까지 휘발되지 않는 bound water의 함량이 증가함에 따라 고온에서도 높은 전도도를 유지 할 수 있었다. 이에 따라 TEOS 200% 함유된 복합막(ST200)은 $120^{\circ}C$, 48%RH에서 나피온보다 높은 수소이온 전도도(0.015 S/cm)를 나타내었다. 또한 순수 SPAES (ST0) 단일막 보다 무기물 첨가로 인해 열 안정성이 증가하였음을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제29권6호
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• pp.1217-1223
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• 2008

A series of Zr,S co-doped $TiO_2$ were synthesized by a modified sol-gel method and characterized by various spectroscopic and analytical techniques. The presence of sulfur caused a red-shift in the absorption band of $TiO_2$. Co-doping of sulfur and zirconium (Zr-$TiO_2$-S) improves the surface properties such as surface area, pore volume, and pore diameter and also enhances the thermal stability of the anatase phase. The Zr-$TiO_2$-S systems are very effective visible-light active catalysts for the degradation of toluene. All reactions follow pseudo firstorder kinetics with the decomposition rate reaching as high as 77% within 4 h. The catalytic activity decreases in the following order: Zr-$TiO_2$-S >$TiO_2$-S >Zr-$TiO_2$>$TiO_2$$\approx$ P-25, demonstrating the synergic effect of codoping with zirconium and sulfur. When the comparison is made within the series of Zr-$TiO_2$-S, the catalytic performance is found to be a function of Zr-contents as follows: 3 wt % Zr-TiO2-S >0.5 wt % Zr-$TiO_2$-S> 5 wt % Zr-$TiO_2$-S >1 wt % Zr-$TiO_2$-S. Higher calcination temperature decreases the reactivity of Zr-$TiO_2$-S.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.254-254
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• 2016

Tin dioxide (SnO2) thin film is one of the most important n-type semiconducting materials having a high transparency and chemical stability. Due to their favorable properties, it has been widely used as a base materials in the transparent conducting substrates, gas sensors, and other various electronic applications. Up to now, SnO2 thin film has been extensively studied by a various deposition techniques such as RF magnetron sputtering, sol-gel process, a solution process, pulsed laser deposition (PLD), chemical vapor deposition (CVD), and atomic layer deposition (ALD) [1-6]. Among them, ALD or plasma-enhanced ALD (PEALD) has recently been focused in diverse applications due to its inherent capability for nanotechnologies. SnO2 thin films can be prepared by ALD or PEALD using halide precursors or using various metal-organic (MO) precursors. In the literature, there are many reports on the ALD and PEALD processes for depositing SnO2 thin films using MO precursors [7-8]. However, only ALD-SnO2 processes has been reported for halide precursors and PEALD-SnO2 process has not been reported yet. Herein, therefore, we report the first PEALD process of SnO2 thin films using SnCl4 and oxygen plasma. In this work, the growth kinetics of PEALD-SnO2 as well as their physical and chemical properties were systemically investigated. Moreover, some promising applications of this process will be shown at the end of presentation.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 추계학술발표대회
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• pp.29.1-29.1
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• 2011

The selective catalytic reduction (SCR) of $MnO_x$ with $NH_3$ is an effective method for the removal of $MnO_x$ from stationary system. The typical catalyst for this method is $V_2O_5-WO_3(MoO_3)/TiO_2$, caused by the high activity and stability. However, This catalyst is active within $300{\sim}400^{\circ}C$ and occurs the pore plugging from the deposition of ammonium sulfate salts on the catalysts surface. It needs to locate the SCR unit after the desulfurizer and electrostatic precipitator without reheating of the flue gas as well as deposition of dust on the catalyst. The manganese oxides supported on titania catalysts have attracted interest because of its high SCR activity at low temperature. The catalytic activity of $MnO_x/TiO_2$ SCR catalyst with different manganese precursors have investigated for low-temperature SCR in terms of structural, morphological, and physico-chemical analyses. The $MnO_x/TiO_2$ were prepared from three different precursors such as manganese nitrate, manganese acetate (II), and manganese acetate (III) by the sol-gel method and then it calcinated at $500^{\circ}C$ for 2 hr. The structural analysis was carried out to identify the phase transition and the change intensity of catalytic activity by various manganese precursors was analyzed by FT-IR and Raman spectroscopy. These different precursors also led to various surface Mn concentrations indicated by SEM. The Mn acetate (III) tends to be more suppressive the crystalline phase (rutile), and it has not only smaller particle size, but also better distributed than the others. It was confirmed that the catalytic activity of MA (III)-$MnO_x/TiO_2$ was the highest among them.