• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.135-138
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• 2001

폴리프로필렌(PP)은 염료와 반응할 수 있는 염착 좌석이 없기 때문에 염색이 불가능하고 열 안정성 및 광 안정성이 부족한 섬유로써 1970년대까지 의류용 섬유로 그다지 주목을 받지 못하였다. 하지만, 좋은 성능을 가진 각종 첨가제가 개발되었고, 상용성이 좋은 안료가 개발이 되면서 그런 단점들이 더 이상 문제가 되지 않을 뿐만 아니라, 안료를 사용함으로써 염색을 하는 다른 섬유들보다 일광 견뢰도 측면에서 매우 유리하고 폴리에스테르나 나일론 등에 비해 값이 싸다는 장점이 있기 때문에 적당한 용도로 전개하면 새로운 소재로의 가치가 있다. (중략)

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.04a
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• pp.29-29
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• 1998

고체 추진제 연소불안정에 관한 해석은 준-정상 1차원 해석인 QSHOD(Quasi-Steady Homogcneous One-Dimension)에 의하여 단순화된 지배방정식을 이용하여 응축영역을 해석하는 것이 일반적이다. 이때 외부교란에 대한 기체영역과 표면반응 영역의 응답은 화학반응이 발생하지 않는 고체영역의 응답에 비하여 매우 빠르므로 준-정상적인 거동을 한다. 본 연구에서는 복사열전달에 의한 열속(heat flux)이 고체 추진제의 표면에 존재하며 이 중의 일부가 고체영역에서 흡수될 때 표면에서의 선형교란을 고려한 ZN(Zeldovich-Novozhilov) 방법을 이용하여 연소불안정 현상을 이론적으로 해석하여 연소불안정 현상을 설명할 수 있는 연소 응답함수를 구하였다. 본 연구에서 얻어진 응답함수를 해석함으로써, Zebrowski등$^{(5)}$ 에 의하여 얻어진 복사열 교란에 대한 응답함수가 과소 평가된 응답특성을 나타내고 있음을 알았다. 또한 응답함수의 고유불안정성을 판별하는 민감계수 r과 k의 영역의 해석으로부터 SOn등$^{(6)}$ 에 의하여 밝혀진 안정 경계선의 안정한 영역보다 본 연구에서 구한 안정 경계영역이 줄어드는 경향을 보여주고 있다. 이것은 (6)에서 과소 평가된 복사열전달의 영향을 수정한 결과 때문이다.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.09a
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• pp.23-38
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• 1995

고분자막에 의한 기체분리는 심냉분리법, 흡수법, 흡착법등에 비하여 에너지가 절약되며 장치가 간결하고 운전비용이 낮은 이점 때문에 여러가지 기체혼합물에 대하여 여러가지 목적으로 응용되기에 이르렀다. O$_{2}$/N$_{2}$ 분리막으로 요구되는 기본특성은 1) 높은 O$_{2}$ 투과성 2) 높은 O$_{2}$ 선택성 3) 막 형성에 충분한 기계적 강도 4) 열, 화학적으로 안정성이 있어야 한다. 그런데 투과계수 P$_{O_(2)}$와 투과선택도 P$_{O_(2)}$/P$_{N_(2)}$ 관계 Fig.2 에서 보는 바와 샅이 대체로 투과선택성은 상반관계에 있어서 polyimide는 높은 선택성을 나타내고 기계적 강도가 좋고 높은 열에 대하여 안정하기 때문에 일단 막재료로 양호한 조건을 갖추고 있으나 투과계수가 크지 않아 선택도를 크게 감소시키지 않으면서 투과계수를 향성시키려는 노력이 경주되고 있다. 따라서 polyimide의 화학구조와 투과계수, 투과선택도의 관계를 고찰하는 것은 대단히 중요하다. 특히 최근에는 polyimide의 화학구조를 계통적으로 변화 시켜가면서 구조와 투과특성을 고찰한 연구가 많으며, 이러한 연구를 총망라하여 화학구조와 투과특성을 고찰한 훌륭한 총설들이 발표되어왔다. Fig.3에는 지금까지 연구된 중요한 polyimide를 형성하는 dianhydride와 diamine의 구조식을 표시하였으며 이들 구조의 변화에 의하여 기체투과계수와 투과선택도가 어떤 영향을 받는지 고찰하고자 한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.442-450
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• 2016

This study aims to determine the antimicrobial activity of fermented Cheonggukjang extract using the new Strain, Bacillus amyloliquefaciens NBF11-1, which was first found on the surface of the node part of bamboo stems, but has been studied very little so far. Bacillus subtilis NG24, which is the traditional fermented strain of Cheonggukjang, was selected as the control group and a comparative analysis was performed. The experimental method included measurements of the antimicrobial activity, minimum inhibitory concentration (MIC) and heat and pH stability. B. amyloliquefaciens NBF11-1 had stronger antimicrobial activity than B. subtilis NG24 against the gram-positive bacteria, C. perfringens and S. aureus and the gram-negative bacteria, A. faecalis and E. coli among the six species of pathogenic bacteria studied. When the minimum inhibitory concentration was measured, B. amyloliquefaciens NBF11-1 in C. perfringens, S. aureus, A. faecalis, and E. coli had an inhibitory effect at concentrations of 0.01 %, 0.21 %, 0.45 % and 0.29 %, respectively, compared to B. subtilis NG24. When the heat and pH stability was measured, B. subtilis NG24 and B. amyloliquefaciens NBF11-1 Cheonggukjang extract did not show any decrease in activity when held at a temperature of $121^{\circ}C$ for 15 minutes and at pH values ranging from 2 to 10 and were therefore considered to be relatively stable against heat and pH changes.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.7
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• pp.969-974
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• 2011

This study was performed to investigate the inhibitory activity of Ecklonia cava (EC) against lipase and the stability of this activity under various heat and pH conditions. As a result, EC ethanol extract showed lipase inhibitory activity of 59, 34 and 19% at concentrations of 5, 2.5 and 1 mg/mL, whereas the water extract showed low inhibitory activity at all concentrations compared to that of the ethanol extracts. In a heat and pH stability test, the inhibitory activity of the EC ethanol extract increased with heat treatment at $121^{\circ}C$ for 15 min compared with the control and was stable in the pH range of 2~10. Therefore, the EC ethanol extract could be useful as a natural anti-obesity agent.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2012.05a
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• pp.293-294
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• 2012

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2011.10a
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• pp.449-450
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• 2011

• KSBB Journal
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• v.23 no.1
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• pp.48-53
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• 2008

Lectin was isolated from locular fluid of tomato by affinity chromatography using Sephadex G-200, and studied its some biochemical properties. SDS-PAGE of the isolated lectin revealed a tetramer composed of two identical subunits with molecular weights of 39 and 23 kDa. The isolated lectin was agglutinated by trypsin-treated human ABO type blood erythrocytes with similar potency, and the most activity of agglutination was found at B type blood erythrocyte. This lectin showed maximum thermal stability at $70^{\circ}C$, and was relatively stable to heat with the higher activity at $40-80^{\circ}C$. The optimal temperature and pH of this lectin were $50^{\circ}C$ and pH 7.0, respectively.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.1
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• pp.42-49
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• 2021

As a measure of susceptibility on the combustion instability, thermo-acoustic instabilities in rocket combustion system was considered for the estimation of the operational stability margin. Growth rate, which governs the asymptotic stability behavior of the system, was determined from the dynamic data measured during combustion tests in order to understand the dynamic characteristics of combustor system. Frequency transform technique was first applied to determine the system parameters such as growth rate and/or damping coefficient for an interested mode from the time series pressure data, and the PDFs of pressure amplitude were extracted from the amplitude envelope of pressure oscillation for the stochastic analysis.

• Korean Journal of Food Science and Technology
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• v.27 no.2
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• pp.170-175
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• 1995

Physical and physiological properties of isomaltooligosaccaride (IMO), fructooligosaccharide (FO) and sucrose were investigated. The viscosity and moisture retention power of IMO were similar to those of FO. IMO had an excellent heat and pH stability compared with FO and sucrose. To investigate the effect of oligosaccharides on the growth of mice, each sample was administered orally to mice for 2 weeks. Weight change, moisture content of feces, weight of appendix and the ratio of Bifidobacterium to total microorganisms in the feces were examined. There were no significant differences in the weight increases and the efficiency of feeds. Moisture content of feces was highest in the IMO feeding group, and IMO promoted selectively the growth of Bifidobacterium. On the other hand, FO group showed bigger cecum than other groups.