• Polymer(Korea)
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• v.29 no.6
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• pp.571-574
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• 2005

The aromatic hyperbranched polyamide was synthesized from 5-aminoisophthalic acid by direct polycondensation with triphenylphosphite (TPP) catalyst as a condensing agent. The modification of end-groups in the resulting hyperbranched polymer (HBP) with various alkyl alcohols were conducted. The modification of end-groups of HBP by alkyl groups resulted in an improved solubility in the THF comparing to that of the carboxylic acid-terminated aromatic HBP, Also, 10 wt$\%$ weight loss temperature decreased by increasing the length of alkyl group.

• The Korean Journal of Food And Nutrition
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• v.14 no.3
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• pp.263-268
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• 2001

NaIO$_4$-산화 전분당을 Bacillus licheniformis의 $\alpha$-아밀라아제의 반응시켜서 시프염기 형성으로 당단백질로 변형시켜서 안정성을 확인하였다. 10$0^{\circ}C$에서의 열안정성은 10분 뒤에, pH 9.7에서 변형한 효소 비변형 효소의 순으로 높았다. 그러나 변형 및 안정성에 $\alpha$-cyclodextrin($\alpha$-CD)을 사용한 결과 큰 차이는 나지 않았다. pH 8.0에서 $\alpha$-CD 존재하에 변형한 효소는 pH 8~11dml 알칼리쪽에서 가장 높은 안정성을 나타냈으나, pH 5~7사이에는 다른 효소보다 낮았다. pH 9.7에서 변형하지 않은 효소는 pH 5부터 pH 13까지 서서히 증가하였고 pH 9.7에서 $\alpha$-CD존재 하의 효소는 pH 5부터 7까지 증가하다가 그 후 pH13까지 서서히 감소하였다. $\alpha$-CD존재하의 비변형 효소는 pH 7과 10에서 피크를나타낸 다음 pH12이후에는 급격히 낮아졌다. 변형한 효소는 HPLC 의 유출시간이 빨라wu서 변형하지 않은 효소보다 분자량이 큰 것으로 나타났다. 분자량 크기는 비변형 효소

• Korean Journal of Agricultural Science
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• v.41 no.2
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• pp.141-147
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• 2014

Diacylglycerol-oil (DAG oil) and four kinds of fatty acids [C16:0, C18:0, perillar oil-hydrolyzate(C18:3, 59.7%) and docosahexaenoic acid(DHA, C22:6, 63.7%)] were enzymatically esterified with 1:0.5, 1:1 and 1:1.5 molar ratio (DAG oil: fatty acids) to produce structured DAG. The reaction mixture were catalyzed by addition of sn-1,3 specific Lipozyme RMIM with 10 wt% of total substrates, and reacted for 1, 3, 6 and 24 hr at $62^{\circ}C$ with 220 rpm on the shaking water bath. The produced DAG were analyzed by TLC. In the result, the proportion of each fatty acid [(C16:0, C18:0, perilla oil-hydrolysate(C18:3, 59.7%) and DHA(C22:6, 63.7%)] on DAG products were increased as molar ratios of substrate increased. Among them, DHA showed the least reaction rate in which 24.2 % of DHA was found in the structured DAG molecules after 24 hr reaction with 1:1.5 molar substrate amount ratio.

• Journal of the Korean Ceramic Society
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• v.43 no.1 s.284
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• pp.38-41
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• 2006

Surface of PC (Polycarbonate) and PES (Polyethersulphone) treated by plasma modification with rf power from 50 W to 200 W substrates in Ar (3 sccm), $O_2$ (12 sccm) atmosphere. From the results of modified substrates in XPS (X-ray Photoelectron Spectroscopy), the ratio of oxide containing bond increased with rf power. As the rf power was 200 W, the contact angle was the lowest value of 14.09 degree. And the datum from AFM (Atomic Force Microscopy), rms roughness value of PES and PC substrates increased with rf power. We could deposit $Ta_2O_5$ with good adhesion on plasma treated PES and PC substrates using by in-situ rf magnetron sputter.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.182-190
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• 1997

Recently to develope an automobile with better properties, much researches and investments are executed in many countries. In this paper, it is intended to minimize the weight of an engine block without changing the dynamic characteristics. The weight minimization is executed by the sensitivity of the natural frequency of the engine block. To decrease the engine weight, much less thickness than the original thickness of the engine is selected to initial value and the structure modification is performed to recover the dynamic characteristics of the engine. Here, the original thickness of the engine is 8mm and the initial thickness is selected to 5mm, 6mm and the number if the natural frequencies fitted are 2, 6, 7, respectively. As the results, it is found that; (1) the weight of each case could be reduced without changing the objective natural frequencies. Specially, in the case of fitting 2 natural frequencies with 5mm initial thickness the weight could be reduced to 4.21kg(23.3% for engine weight). (2) according to the driving frequency range of engine, the weight minimization could be performed choicely, (3) improving a vibration characteristics of a orignal structure, the weight minimization could be performed.

• Bulletin of the Korean Chemical Society
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• v.29 no.3
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• pp.585-589
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• 2008

Second-order rate constants (kN) have been measured for reactions of Y-substituted phenyl 2-thiophenecarboxylates (6a-h) with morpholine and piperidine in 80 mol % H2O/20 mol % DMSO at 25.0 0.1 oC. The Brnsted-type plot for the reactions of 6a-h with morpholine is linear with b lg = 1.29, indicating that the reactions proceed through a tetrahedral zwitterionic intermediate (T?). On the other hand, the Brnsted-type plot for the reactions of 6a-h with piperidine exhibits a downward curvature, implying that a change in the rate-determining step occurs on changing the substituent Y in the leaving group. Dissection of kN into microscopic rate constants (i.e., k1 and k2/k1 ratio) has revealed that k1 is smaller for the reactions of 6a-h than for those of Y-substituted phenyl 2-furoates (5a-h), while the k2/k1 ratio is almost the same for the reactions of 5a-h and 6a-h. It is also reported that modification of the nonleaving group from the furoyl (5a-h) to the thiophenecarbonyl (6a-h) does not influence pKao (defined as the pKa at the center of the Brnsted curvature) as well as the k2/k1 ratio.

• Communications for Statistical Applications and Methods
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• v.10 no.3
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• pp.627-635
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• 2003

In this short communication we discuss the bias problem of C4.5 in split variable selection and suggest a method to reduce the variable selection bias among categorical predictor variables. A penalty proportional to the number of categories is applied to the splitting criterion gain of C4.5. The results of empirical comparisons show that the proposed modification of C4.5 reduces the size of classification trees.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.84.2-84
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• 2003

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3861-3863
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• 2012

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.148.2-148
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• 2002