• Fibers and Polymers
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• 제5권1호
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• pp.31-38
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• 2004

In the present paper, a variety of fiber reinforcements, for instance, stabilized OXI-PAN fibers, quasi-carbon fibers, commercial carbon fibers, and their woven fabric forms, have been utilized to fabricate pseudo-unidirectional (pseudo-UD) and 2-directional (2D) phenolic matrix composites using a compression molding method. Prior to fabricating quasi-carbon fiber/phenolic (QC/P) composites, stabilized OXI-PAN fibers and fabrics were heat-treated under low temperature carbonization processes to prepare quasi-carbon fibers and fabrics. The thermal conductivity and thermal expansion/contraction behavior of QC/P composites have been investigated and compared with those of carbon fiber/phenolic (C/P) and stabilized fiber/phenolic composites. Also, the chemical compositions of the fibers used have been characterized. The results suggest that use of proper quasi-carbonization process may control effectively not only the chemical compositions of resulting quasi-carbon fibers but also the thermal conductivity and thermal expansion behavior of quasi-carbon fibers/phenolic composites in the intermediate range between stabilized PAN fiber- and carbon fiber-reinforced phenolic composites.

• Carbon letters
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• 제26권
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• pp.107-111
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• 2018

• 한국고분자학회지:고분자과학과기술
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• 제20권5호
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• pp.465-471
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• 2009

• Korean Chemical Engineering Research
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• 제52권1호
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• pp.63-67
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• 2014

페놀-포름알데히드를 이용하여 레졸형 구형 페놀수지 입자를 합성함에 있어 반응물의 조성이 입도분포, 수율 및 밀도에 미치는 영향을 확인하였다. 분산매의 양을 감소시킴에 따라 현탁액의 점도가 증가하며 이로 인해 입도분포의 변화 및 응집 현상의 원인이 됨을 확인하였고, 안정제의 양을 증가시킴에 따라 현탁입자의 표면적을 증가시키기 위해 평균입도가 감소하는 것을 확인하였다. 적정량 이상의 경화제의 사용은 입도분포 및 수율에는 영향을 미치지 않으나 형성된 입자 내부의 격렬한 경화반응으로 인해 발생하는 물분자의 탈출이 원활하지 않게 되어 밀도가 감소하는 것을 SEM 사진을 통해 확인하였다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2018년도 추계학술대회
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• pp.42-42
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• 2018

Anthocyanins has a strong antioxidant capacity but exhibit poor stability in water. Therefore, stability of anthocyanin from purple potato (Solanum tuberosum L.) was encapsulated by the application of food polymers. Solid formulation of purple potato was prepared using whey protein, tapioca and lecithin by capillary rheometer at $80^{\circ}C$. The ratio of the polymer and potato powder was 2:8. Total phenolic compound, total flavonoid, total anthocyanin and antioxidant activity was investigated by the spectrophotometer. Result revealed that total phenolic compound (TP) ($5321{\mu}g/100g$), total flavonoid (TF) ($1352{\mu}g/100g$) total anthocyanin (TA) ($764{\mu}g/100g$) and free radical antioxidant activity (DPPH) (86%) was higher in 0.01 M acetic acid mediated lecithin based formulation compared to control (Potato powder) (TP: $1357{\mu}g/100g$; TF) ($634{\mu}g/100g$, TA) ($264{\mu}g/100g\;DPPH$) (64%). Lecithin is a strong emulsifier having capacity to extract bioactive compound and encapsulate extracted compound by nonpolar tail and negatively charged head. Therefore, it would be concluded that lecithin might be used as an encapsulating agent for the bioactive compound from purple potato.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2018년도 추계학술대회
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• pp.274-274
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• 2018

Anthocyanins has a strong antioxidant capacity but exhibit poor stability in water. Therefore, stability of anthocyanin from purple potato (Solanum tuberosum L.) was encapsulated by the application of food polymers. Solid formulation of purple potato was prepared using whey protein, tapioca and lecithin by capillary rheometer at $80^{\circ}C$. The ratio of the polymer and potato powder was 2:8. Total phenolic compound, total flavonoid, total anthocyanin and antioxidant activity was investigated by the spectrophotometer. Result revealed that total phenolic compound (TP) ($5321{\mu}g/100g$), total flavonoid (TF) ($1352{\mu}g/100g$) total anthocyanin (TA) ($764{\mu}g/100g$) and free radical antioxidant activity (DPPH) (86%) was higher in 0.01 M acetic acid mediated lecithin based formulation compared to control (Potato powder) (TP: $1357{\mu}g/100g$; TF) ($634{\mu}g/100g$, TA) ($264{\mu}g/100g\;DPPH$) (64%). Lecithin is a strong emulsifier having capacity to extract bioactive compound and encapsulate extracted compound by nonpolar tail and negatively charged head. Therefore, it would be concluded that lecithin might be used as an encapsulating agent for the bioactive compound from purple potato.

• Carbon letters
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• 제17권1호
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• pp.33-38
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• 2016

In the present study, exfoliated graphite nanoplatelets (xGnP) with different particle sizes were coated onto polyacrylonitrile-based carbon fibers by a direct coating method. The flexural properties, interlaminar shear strength, and the morphology of the xGnP-coated carbon fiber/phenolic matrix composites were investigated in terms of their longitudinal flexural strength and modulus, interlaminar shear strength, and by optical and scanning electron microscopic observations. The results were compared with a phenolic matrix composite counterpart prepared without xGnP. The flexural properties and interlaminar shear strength of the xGnP-coated carbon fiber/phenolic matrix composites were found to be higher than those of the uncoated composite. The flexural and interlaminar shear strengths were affected by the particle size of the xGnP, while the particle size had no significant effect on the flexural modulus. It seems that the interfacial contacts between the xGnP-coated carbon fibers and the phenolic matrix play a role in enhancing the flexural strength as well as the interlaminar shear strength of the composites.

• 생약학회지
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• 제11권3_4호통권43호
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• pp.153-162
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• 1980

1) The hydroxy-substitution in the simple phenolic compounds follows an additivity rule in the chemical shifts of their aromatic carbon atoms. In para-and ortho-effects is a good agreement between calculated and measured values, but the meta-effect is not certain. 2) The additivity rule was applied to assign the chemical shifts of catechins. 3) The nuclear overhauser effect was applied to assign the chemical shifts of C-8 and C-6 atoms of catechins and their polymer. The signal of C-8 is lower in intensity and appear in lower field than C-6. 4) The results of the NOE were applied to determine the bonding positions of catechin units in the catechin dimer and trimer. The bonding positions are C-8a and C-8b atoms of the second and third catechin units. 5) It was tried to determine the conformation of the catechin dimer and trimer by analysing the signal shapes of C-3' and C-4' atoms in the catechol moieties. The catechol moieties lie in opposite side in the dimer and trimer structure. A combined analysis of $^{13}C-and\;^1H-NMR$ results lead to the suggestion that such a catechin polymer is a zigzag planar form.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.146-149
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• 1999

Langmur-Blodgett (LB) method has a unique characteristic of making molecularly mutilayered aggregation structures. LB method makes the thickness of organic insulation layer controllable at molecular scale in various electronic devices. In this study, the organic materials applicable to crosslinked LB insulation layers of electronic devices have developed and the electrical properties of their LB films have examined such as Brewster angle microscopy(BAM), Scanning Maxwell-stress microscopy(SMM), and Current-voltage(1-V) properties.

• Macromolecular Research
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• 제17권2호
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• pp.121-127
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• 2009

The cure kinetics of the epoxy-layered, silicate nanocomposites were studied by differential scanning calorimetry under isothermal and dynamic conditions. The materials used in this study were o-cresol novolac epoxy resin and phenol novolac hardener, with organically modified layered silicates. Various kinetic parameters, including the reaction order, activation energy, and kinetic rate constants, were investigated, and the storage stability of the epoxy-layered silicate nanocomposites was measured. To synthesize the epoxy-layered silicate nanocomposites, the phenolic hardener underwent pre-intercalation by layered silicate. From the cure kinetics analyses, the organically modified layered silicate decreased the activation energy during cure reaction in the epoxy/phenolic hardener system. In addition, the storage stability of the nanocomposite with the pre-intercalated phenolic hardener was significantly increased compared to that of the nanocomposite with direct mixing of epoxy, phenolic hardener, and layered silicate. This was due to the protective effect of the reaction between onium ions and epoxide groups.