• Applied Biological Chemistry
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• v.48 no.2
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• pp.109-114
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• 2005

A bacterium capable of emulsifying hydrocarbon, n-hexadecane, and decreasing surface tension of the culture media using oil collapsing method was isolated. The bacterium was partially identified as Bacillus sp. and named BJS-51. n-Hexadecane was the most effective carbon source for production of biosurfactant. Surface tension was decreased from 76 dyne/cm to 31 dyne/cm and CMD (critical micelle dilution) had the highest value of 5.7 at 3% n-hexadecane. Ammonium phosphate was the most effective nitrogen source, when C/N ratio was 60, surface tension and CMD were 29 dyne/cm and 9.2, respectively. Optimum pH and temperature were 7.2 and $30^{\circ}C$, respectively. Produced biosurfactant was extracted and purified using organic solvent extraction method and preparative HPLC systems. After analysis by various color reaction, this biosurfactant was identified as lipopolysaccharide. Surface tension and CMC (critical micelle concentration) of purified biosurfactant were 27 dyne/cm and 0.08 g/l, repectively. CMD was 9.2, so the yield of biosurfactant was about 0.74 g/l at the optimal conditions. The biosurfactant was very stable at wide range of $pH\;2{\sim}12$ with surface tension $29{\sim}31\;dyne/cm$ and showed $29{\sim}30\;dyne/cm$ of surface tension after heat treatment at $100^{\circ}C$ for 60 min.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.516-521
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• 2014

Axial and overall heat transfer coefficients were investigated in a bubble column with relatively high viscous and low surface tension media. Effects of superficial gas velocity (0.02~0.1 m/s), liquid viscosity ($0.1{\sim}0.3Pa{\cdot}s$) and surface tension ($66.1{\sim}72.9{\times}10^{-3}N/m$) on the local and overall heat transfer coefficients were examined. The heat transfer field was composed of the immersed heater and the bubble column; a vertical heater was installed at the center of the column coaxially. The heat transfer coefficient was determined by measuring the temperature differences continuously between the heater surface and the column which was bubbling in a given operating condition, with the knowledge of heat supply to the heater. The local heat transfer coefficient increased with increasing superficial gas velocity but decreased with increasing axial distance from the gas distributor and liquid surface tension. The overall heat transfer coefficient increased with increasing superficial gas velocity but decreased with increasing liquid viscosity or surface tension. The overall heat transfer coefficient was well correlated in terms of operating variables such as superficial gas velocity, liquid surface tension and liquid viscosity with a correlation coefficient of 0.91, and in terms of dimensionless groups such as Nusselt, Reynolds, Prandtl and Weber numbers with a correlation of 0.92; $$h=2502U^{0.236}_{G}{\mu}^{-0.250}_{L}{\sigma}^{-0.028}_L$$ $$Nu=325Re^{0.180}Pr^{-0.067}We^{0.028}$$.

• Journal of the Korean Society of Visualization
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• v.3 no.1
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• pp.51-57
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• 2005

Vertices terminating at free surface have been investigated extensively. Most of investigations, however, are focused on surface parallel vortices and little has been known about surface normal vortex or columnar vortex. Visualized experimental results utilizing LIF technique are discussed fur the purpose of characterization of columnar vortex interacting with a clean and a contaminated free surfaces and a solid body interface in the present investigation. The results reveal that surface tension changes due to surface contamination although bulk viscosity remains constant and eventually the behavior of a columnar vortex interacting with a contaminated free surface and a solid body interface are totally different from the clean free surface case.

• Journal of the Korean Ceramic Society
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• v.33 no.12
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• pp.1325-1330
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• 1996

A new numerical method for determining the surface tension of a liquid drop by experimental measurement of the contour of the sessile drop is explained. in the present method a very simple and short computer program enables the calculation of surface tension in a few seconds even by a low speed personal computer. It need not the use of any other numerical tables or complex techniques. X and Z-corrdinates at one point on the contour of a sessile drop and the tangential angle at that point are all the data needed when the density of the drop is known. The results were compared with the values derived by a conventional method. This method can be used for the confirmation of measuring accuracy. Also the same concepts can be applied for the pendant drop method by changing only the sign of Z-coordinate from "+" to "-"ot; to "-"ot;-"quot.

• Journal of Life Science
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• v.14 no.5
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• pp.834-839
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• 2004

To improve and oil degrading activity, the lipase gene from Pseudomonase sp. was transformed into Klebsiella sp. KCL-l, an oil degrading bacterium. The selected trasformant was named as a KCL-1/pET-Lip. The surface tension of culture broth of KCL-1/pET-Lip was decreased to 33 dyne/cm from 55 dyne/cm using 4% (v/v) soybean oil as sole carbon source. The surface tension were 44 and 37.5 dyne/cm, to 2% (w/v) glucose and 4% (v/v) kerosene medium, respectively. The emulsification activity of the biosurfactant solution containing lipase of KCL-l/pET-Lip improved better than wild type KCL-l. The soybean oil was most efficient carbon source and substrate for surface activity and emulsification activity of KCL-1/pET-Lip. The expression of lipase was confirmed by SDS-PAGE.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.59.2-59.2
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• 2009

화학보호복은 독성이 있는 화학물질 및 미세분진등에 대해 공기를 차단하며 완전 밀폐형으로 공기호흡기 및 에어라인 같은 호흡보호장치와 함께 착용하여 신체부위를 보호한다. 그 예로 생물/화학보호복은 유독하고 해로운 생물/화학물질로 부터 인체를 보호해준다. 이들 보호복은 다양한 환경이 노출되어 장시간 작업을 위해서 오랜시간 보호성능을 유지해야한다. 특히, 이런 원단의 구성은 플라스틱과 고무류의 다층구조로 구성되어있다. 플라스틱류(폴리에틸렌, PTFE 등)는 표면장력이 너무 낮아 접착하는데 어려운 점이 많이 대두된다. 일반적인 표면처리방법은 크게 물리화학적 방법으로 4가지로 분류한다. 화학적산화, 불꽃처리, 플라즈마처리, UV 방사법 등이 있다. 이들 중에서 가장 간단한 산화처리는 플라즈마처리다. 이처리는 상온/상압하에서 대기 중 또는 가스내에 방전에 의해 플라즈마를 형성하고 이 플라즈마가 대상물의 표면분자와 격렬히 반응하게 하여 표면의 분자구조를 변화시킴에 따라 소수성의 표면에 Carboxyl, hydroxyl과 carbonyl과 같은 친수성으로 변하여 결합능력을 증가 시켜 표면장력을 높여주는 가장 효과적인 방법이다. 플라즈마 표면처리를 하고 나면 육안으로 표면의 변화를 감지할 수 없지만 접착, 잉크, 코팅을 잘 받아들이는 결과를 가져온다. 플라즈마 표면처리의 효과는 주로 부도체의 필름이나 합성수지 계열의 인쇄성과 접착성을 향상시키고자 많이 활용되고 있는 실정이다. 특히, 화학보호복과 같은 플라스틱류인 다양한 고분자 합성수지(Polyethylene, polypropylene, nylon, vinyl, PVC, PET 등)에 적용가능하다. 본 연구에서는 플라즈마처리조건에 영향을 주는 변수들을 고려하여 실험계획법(DOE, RSM)을 이용하여 최적화된 플라즈마 공정을 향상시키고자한다.

• Korean Chemical Engineering Research
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• v.48 no.4
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• pp.444-449
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• 2010

In this study, the petroleum sulfonate(PS) was synthesized from pyolyzed fuel oil by sulfonation reaction with sulfuric acid. The PS synthesized had surfactant behaviors relating to the interfacial properties such as surface tension, surface adsorption, and wetting, etc. These interfacial properties were affected by the sulfonation ratio in the synthesis. As the sulfonation ratio increased, the surface tension of the PS aqueous solution decreased. However, when the ratio was too high, the surface tension was increased due to the extremely higher value of hydrophilicity of PS. At the optimum sulfonation ratio, the PS had a good wettability on the cement particles and a good fluidity of the cement mortar with a high adsorption.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1996.10b
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• pp.190-192
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• 1996

본 연구는 기존의 Water-Lithium Bromide(H2O/LiBr) 용액에 비해 부식성이 낮은 Water-Lithium bromide-Lithium Nitrate계(H2O/LiBr-LiNO3)용액의 용해도, 증기압, 점도, 표면장력 등의 물리적 성질을 조사하였다. 또한 용해도가 가장 큰 최적의 혼합 몰비를 구하여 증기압 및 점도, 표면장력등의 물성을 구함으로써 흡수식 냉온수기용 홉수제 개발의 기본 자료를 확보하였다. 이러한 연구 결과로부터 다성분 Lithium 염 혼합물계로 이루어진 흡수용액 개발의 기초자료로 이용하고자 한다.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2001.11a
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• pp.168-170
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• 2001

생물 계면활성제의 개발을 위해 MNNG(N-Methyl-N-Nitro- Nitrosoguanidine), EMS, UV radiator random mutation을 통해 가장 우수한 biosurfactant 생산 균주를 선별하였는데 MNNG를 처리한 균주가 유화활성 1.950, 표면장력 29.0dyne/cm으로 공시균주인 Pseudomonas aeruginosa EL-MS 유화활성 0.456과 표면장력 33.0dyne/cm에 비해 우수하였다.

• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.231-233
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• 2001

최근 나노섬유기술 (NT)과 더불어 전기방사의 중요성이 날로 증가하고 있는데, 전기방사란 고분자 용액 및 용융된 고분자에 고전압을 걸어주어 부직포를 받아주는 collector와 방사되는 tip사이에 전기장을 형성시켜 부직포를 제조하는 방법이다. 전기장의 세기가 고분자 용액의 표면 장력과 같을 경우 전하를 띤 고분자 용액은 tip부분에 맺히게 되며, 고분자가 가지고 있는 표면장력 이상의 전압을 걸어주면 하전된 고분자 방울은 안정되지 못하고 접지 방향으로 분산 (jet form) 하게 된다. (중략)