• 한국세라믹학회지
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• 제40권7호
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• pp.690-695
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• 2003

고순도의 세라믹분말을 합성할 수 있는 용액 화학적 합성방법의 하나로서, 폴리머를 이용한 분말합성방법이 개발되었다. 본 연구에서는 PVA(Polyvinyl Alcohol)을 이용하여 니켈 알루미네이트(NiAl$_2$O$_4$) 분말을 합성하였다. PVA 첨가에 의하여 용액내의 금속 양이온들의 분산을 극대화하며, 순수한 니켈 알루미네이트를 얻기 위한 결정화 온도를 낮출 수 있었다. PVA 폴리머를 이용함으로써 분쇄가 용이한 부드러운 팽창성 분말을 얻을 수 있었으며, 볼 밀링에 의하여 약 300 nm의 크기를 보이는 좁은 입도의 미세한 분말이 얻어졌다 1$600^{\circ}C$, 1시간 소결에 의하여 4.35 g/㎤의 밀도를 보이는 치밀한 니켈 알루미네이트를 얻을 수 있었으며, 측정된 경도, 곡강도, 파괴인성 및 열팽창계수 값은 각각 14.2 ㎬, 304 ㎫, 4.8 ㎫.m$^{1}$2/과 9.8$\times$$10^{-6}$/$^{\circ}C$를 보였다.

• 한국세라믹학회지
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• 제46권6호
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• pp.639-642
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• 2009

The research was performed to find out the optimum firing condition for the $SnO_2-TiO_2-V_2O_5$ system yellow pigment. The pigment based on $SnO_2-V_2O_5$ system showed very intense yellow color and it was used widely in ceramics industry. Synthesized pigment, with partial substitutions of $SnO_2\;by\;TiO_2$, was fired at $1300{^{\circ}C}$ soaking 1h and it showed bright yellow color. $SnO_2-TiO_2-V_2O_5$ system was very more intensive changes in yellow color by colorimetric value $b^*$ than $SnO_2-V_2O_5$ system. Synthesized yellow pigments were characterized by X-ray diffraction (XRD), FT-IR, and UV-vis spectroscopy. The best composition for yellow pigment was 93:7:0.5(mole%) for $SnO_2-V_2O_5-TiO_2$. The measurement of CIE $L^*a^*b^*$ of pigment was $L^*(78.82),\;a^*(-4.88)\;and\;b^*$(59.25).

• 한국수소및신에너지학회논문집
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• 제25권2호
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• pp.151-160
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• 2014

CL-SPEEK/Cs-TPA/$CeO_2$ composite membrane was prepared for polymer electrolyte membrane water electrolysis (PEMWE). In order to improve the electrochemical, mechanical, durabilities and electrocatalytic characteristics, engineering plastic of polyether ether ketone (PEEK) as polymer matrix was sulfonated and the organic-inorganic blend composite membranes was prepared by loading cesium-substituted tungstophosphoric acid (Cs-TPA) by titration method with cross-linking agent contents of 0.01mL. Ceria ($CeO_2$) was used to scavenge free radicals which attack the membrane in the PEMWE circumstance and to increase the duration of the membrane. CL-SPEEK/$Cs_{(1)}$-TPA/CeriaIn conclusion, 1% membrane showed the optimum results such as 0.119 S/cm at $80^{\circ}C$ of proton conductivity and 62MPa of tensile strength.

• Asian-Australasian Journal of Animal Sciences
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• 제17권5호
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• pp.648-654
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• 2004

This study was carried out to assess whether feeding of alcohol-fermented feeds (AFF) affects the nutritional metabolism and growth characteristics of Korean native steers. Ten steers were randomly assigned to one of two treatment groups. The dietary treatments were AFF (50% commercial beef cattle feed+30% alcohol-fermented soybean curd dregs+20% rice straw) and control (80% commercial beef cattle feed+20% rice straw). The change of serum metabolites and growth characteristics were measured every two months during the whole twelve months experimental period and the relationships between serum metabolites and growth characteristics were simultaneously analyzed. Four hours after feeding AFF, serum alcohol concentration reached its peak with a significantly higher value than that after control feeding (11.9 and 4.9 mg/dl, respectively). Serum glucose and inorganic phosphorus (IP) concentrations (63.1 and 8.4 mg/dl, respectively) of steers fed AFF were higher than those (56.6 and 7.0 mg/dl) fed the control diet. In both treatments, the serum glucose concentration rapidly increased when body weight (BW) of the steer reached about 600kg, while IP concentrations were rapidly diminished at that BW. Lower concentrations of both blood urea nitrogen (BUN) and cholesterol were observed in steers fed AFF up to 450 kg of BW. The IP concentration was correlated with concentrations of BUN, cholesterol and glucose in AFF fed cattle but not in the cattle fed control diets. Average daily gain was higher in steers fed AFF than steers fed control, particularly during the growing stage of cattle. These findings indicated a capability of AFF to improve BW gain of Korean native steers by decreased protein degradation as well as increased fat synthesis.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.5.1-5.1
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• 2010

One of the most important environmental problems is global warming. Global warming is caused by increase in the amounts of water vapor, methane, carbon dioxide and other gases being released into the atmosphere as a result of the burning of fossil fuels. It has thus become important to reduce fossil fuel use. Environmentally friendly preparation of functional materials has, therefore, attracted much interest for environmental problems. Furthermore, nature mimetic processes are recently been of great interest as environmentally friendly one. There have been many studies on fabrication of various functional nanocrystals. Among various nanocrystal fabrication techniques, flux growth is an environmentally friendly, very convenient process and can produce functional nanocrystals at temperatures below the melting points of the solutes. Furthermore, this technique is suitable for the synthesis of crystals having an enhedral habit. In flux growth, the constituents of the materials to be crystallized are dissolved in a suitable flux (solvent) and crystal growth occurs as the solution becomes critically supersaturated. The supersaturation is attained by cooling the solution, by evaporation of the solvent or by a transport process in which the solute is made to flow from a hotter to a cooler region. Many kinds of oxide nanocrystals have been grown in our laboratory. For example, zero- (e.g., particle), one- (e.g., whisker and tube) and two-dimensional (e.g., sheet) nanocrystals were successfully grown by flux method. Our flux-growth technique has some industrial and ecological merits because the nanocrystal fabrication temperatures are far below their melting points and because the used reagents are less harmless to human being and the environment.

• Korean Chemical Engineering Research
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• 제54권4호
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• pp.459-464
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• 2016

본 연구에서는 리튬이온 전지용 실리콘 음극소재의 사이클 안정성 및 율속 특성 향상을 위해 다공성 실리콘/탄소 복합소재의 전기화학적 특성을 조사하였다. 나노 실리카 제조는 스토버 방법을 사용하고 교반 속도, 교반 온도 및 $NH_3$/TEOS 비율을 조절 하여 100~500 nm 크기의 구형 실리카를 합성하였다. 구형 나노 실리카의 마그네슘 열환원과 산처리 과정을 통해 다공성 실리콘을 얻고, 제조된 다공성 실리콘에 Phenolic resin을 탄소전구체로 사용하여 최종적으로 다공성 실리콘/탄소 활물질을 합성하였다. 또한 $LiPF_6$ (EC:DMC:EMC=1:1:1 vol%) 전해액에서 다공성 실리콘/탄소 음극소재의 충 방전, 순환전압 전류, 임피던스 테스트 등의 전기화학적 특성을 조사 하였다. 다공성 실리콘/탄소 복합소재의 음극활물질로서 코인 전지의 성능을 조사한 결과 초기용량 및 40사이클 용량 보존율은 각각 2,006 mAh/g, 55.4%를 나타내었다.

• Composites Research
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• 제33권1호
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• pp.7-12
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• 2020

지난 10년간 효율적인 방열 재료 개발을 위해 유망한 매트릭스로서 액정 에폭시 수지(Liquid crystalline epoxy, LCER)는 많은 주목을 받아 왔다. 본 연구에서는 LECR중에서 대표적인 4,4-diglycidyloxybiphenyl (DP) 에폭시를 이용한 고분자/SWCNT 복합체의 합성과 제조 및 특성 분석을 포함한 포괄적인 연구를 제시한다. 복합 재료의 열전도 특성을 확인해보기 위해 에폭시 수지와 충전제인 단일벽 탄소나노튜브(Single-wall carbon nanotube, SWCNT)로 구성된 복합체 샘플이 준비되었다. 특히 DP 복합체는, LCER의 고도로 정렬 된 미세 구조로 인해 동일한 필러를 사용하는 상업용 에폭시의 복합체에 비해 높은 열 전도성을 보였다. 또한, DP 복합체의 열전도도는 충전제의 양을 조절하여 제어할 수 있으며, 특히 SWCNT의 함량이 50 wt%인 DP 복합체는 열전도도는 2.008 W/mK로 가장 높은 열전도도를 나타내었다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2009년도 춘계학술발표회 논문집
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• pp.23-28
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• 2009

The purpose of this study was to improve not only wet-end performances but also paper characteristics by the modification of various factors like molecular design and ionic characteristics of polyacrylamides First of all physical characteristics were observed after modify molecular design of the cationic polyacrylamides to linear, branched and cross-linked. In addition it was found analysis method to confirm branch degree of cationic polyacrylamides to combine ionic titration characteristics and spectroscopic behavior, After application of these structure modified polyacrylamides to the multiple retention systems with inorganic microparticles, it was found adjusting of branch degree of polyacrylamides was very important to optimize wet-end improvement. Second, After polymerization of amphoteric polyacrylamide to have both of cationic and anionic functional group in the polymer, we observed not only physical characteristics but also wet-end improvement to apply recycled pulp and found that the improvement of solution stability to prevent hydrolysis and increase of ash retention dramatically to compare traditional cationic polyacrylamide retention aid, Finally, After polymerization of anionic polyacrylamide, we observed not only wet-end improvement but also paper characteristics to apply preflocculation of PCC and it was found the improvements of flocculation efficiency, retention, ash retention, optical properties of the paper and bursting strength to compare traditional preflocculant of cationic polyacrylamide.

• 공업화학
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• 제23권3호
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• pp.271-278
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• 2012

본 연구에서는 마이카와 산화 아연을 이용하여 복합 재료를 제조하고, 이를 자외선 차단 크림에 응용하는 연구를 수행하였다. 먼저 마이카와 산화 아연을 각각 3-aminopropyltrimethoxysilane (APTMS)으로 처리하여 표면에 아민기를 생성시켰다. 아민기가 붙은 마이카를 1,4-phenylenediisothiocyanate (PDC)와 반응시켜 표면에 -N=C=S 작용기를 활성화시킨 후, 아민기가 붙어있는 산화 아연과 결합시켜 산화 아연으로 덮인 마이카 복합 재료를 합성하였다. 원소 분석, EDS 분석, 열 중량 분석, SEM 이미지 분석, 형광 이미지 분석, 제타 전위 측정, X-선 회절 분석, DRS UV/Vis 분석을 통하여 고체 생성물의 특성을 규명하였다. 최종적으로 표준 프로토콜로 제조된 자외선 차단 크림의 파장에 따른 투과도를 280~400 nm 범위에서 측정하여 자외선 차단 효과를 확인하였다.

• 자원리싸이클링
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• 제10권6호
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• pp.29-34
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• 2001

석탄회 분말을 다중자연낙하법에 의한 공기분급에 의하여 미립 및 조립의 분말로 정제 및 분급한 후 각각의 분말을 사용하여 뮬라이트 및 제올라이트를 합성하였다 평균 입경이 $6.5mu$m인 미립 석탄회에$ A12$ $O_3$를 첨가한 후 145$0^{\circ}C$ 이상의 온도에서 소성하여 뮬라이트 상의 소결체를 얻었다. 평균 입경 $56.3\mu$m인 조립 석탄회를 사용하여 3.5 M NaOH수용액과 $120^{\circ}C$에서 수열 반응시켜 phillipsite형 제올라이트를 합성하였다. 이와 같은 방법으로 모든 입도의 석탄회 분말을 무기재료의 합성에 이용할 수 있었다.