• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.178-181
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• 2005

토양세척 공정 시 오염물질을 제거하기 위해 사용한 계면활성제를 재사용하기 위해 활성탄을 사용하였으며 이때 계면활성제와 HOC (Hydrophobic Organic Chemical)의 분배를 예측 할 수 있는 모델을 개발하였다. 계면활성제로는 Triton X-100, HOC는 phenanthrene을 활성탄으로는 Darco 20-40 mesh를 사용하였다. 개발된 모델로 계면활성제 주입량, 활성탄 주입량에 따른 계면활성제와 HOC의 분배결과를 각각 전산 모사를 통하여 얻었다. 그 결과 활성탄이 포함된 계 내에서의 계면활성제와 HOC의 분배가 미셀이 형성되는 농도를 전후로 서로 다른 분배 양상을 보였다. 또한 전산모사 결과는 실제 실험결과를 비교적 정확하게 반영함을 알 수 있다.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.326-329
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• 2016

2차원 metal monochalchogenides(MMC) 물질들 중 lattice mismatch가 가장 적은 GaSe와 InS의 $8{\times}1$ lateral heterostructure의 계면 원자 구조와 전자 구조를 Linear combination of atomic orbital 제일원리계산을 이용하여 연구하였다. Arm-chair 와 zigzag 계면에 대해 각각 두 가지 원자 구조를 고려하여 총 네 가지 계면 구조 모델을 정립하고, 각각의 계면에 대해 GaSe-InS의 비율을 다섯 단계(2:6, 3:5, 4:4, 5:3, 6:2)로 바꾸어 가며 relax된 원자구조의 특성과 계면 형성 에너지를 구하였다. 또한, 계면 전자구조 분석을 위하여, 계면으로부터의 위치에 따른 projected density of states의 변화를 규명하였다.

• The Korean Journal of Rheology
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• v.10 no.1
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• pp.14-23
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• 1998

비상용성 고분자 브렌드계인 PS/PP와 EPDM/PP의 유변학적 거동에 미치는 계면의 영향을 알아보았고 그실험 결과를 Park & Lee 모델과 비교하였다. PS/PP와 EPDM/PP 블 렌드계에서의 계면에 의한 전단응력과 법선 응력차에의 기여도는 $textsc{k}$와λ(1-$\mu$), 두 개의 변 수에 의해 잘설명되었다. 특히 계면의 탄성적인 효과와 관련있는 법선응력차 항이 전단 응 력 항보다 더 뚜렷하게 나타났다. 30PS/70PP 블렌드 조성에서는 블렌드의 유변학적 특성이 주로 연속상을 이루는 고분자의 의해 좌우된 반면에 50PS/50PP 블렌드조성에서는 계면에 의한 영향이 더두드러지게 나타났다. 이것은 50/50 블렌드 조성에서 계면의 넓이가 증가한 것과 관계 있다. 그러나 EPDM/PP 블렌드계에서 계면에 의한 응력 항들이 모두 PS/PP 블 렌드계의 그것보다 매우 큰 값을 가졌지만, 그 상대적인 비를 나타내는 $textsc{k}$값은 작았다. 이것 은 블렌드를 구성하고 있는 순수한 성분의 법선응력차 값의 차이가 크기 때문이다. 또한 PS/PP 블렌드계에 대한 동적 계면장력을 Park & Lee 모델을 이용하여 예측해 보았다.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.11
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• pp.735-742
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• 2012

This study tried to find a suitable method for enhancing the foam stability of cationic surfactants that normally generate less foam or no foam. Several trials were made to enhance the foam stability: addition of anionic surfactant, colloids and polymer. Cationic starch (CA-ST) did not form foam at all, while the foam stability of two other cationic surfactant also showed low levels; methyl triethanol ammonium methyl sulfate distearyl ester (CEQ90) for 46 sec. and Cetyl trimethyl ammonium chloride (CM29) for 31 seconds. Foam stability of cationic surfactants were significantly affected by addition of anionic surfactant, sodium dodecyl sulfate (SDS). Foam stability of CA-ST was significantly enhanced by addition of SDS, while those of CEQ90 and CM29 were decreased. Addition of colloids ($SiO_2$, kaolin) and polyvinyl alcohol (PVA) enhanced foam stabilities of CEQ90 and CM29. However, CA-ST did not form foam even in the presence of colloids or PVA. Effect of simultaneous addition of colloids and anionic surfactant on foam stability of cationic surfactant showed that foam stability of cationic surfactant was more influenced by addition of anionic surfactant than colloids. Effect of simultaneous addition of PVA and anionic surfactant on the foam stability of cationic surfactant also showed that presence of anionic surfactant significantly affect the foam stability of cationic surfactant. Foam stability of CA-ST was greatly increased to 8,780 seconds by addition of SDS 0.14% and PVA 2.5%. The foam stability of CA-ST was 8 times higher than CEQ 90. This study suggested that cationic surfactants not forming foam can generate foam by addition of anionic surfactant and its stability can be additionally increased by addition of colloids and PVA. The study results showed that enhancement in foam stability of cationic surfactant was prominently affected by the concentration of anionic surfactant added.

• KSBB Journal
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• v.22 no.1
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• pp.43-47
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• 2007

The effect of surfactant on the hydrolysis of used newspaper was investigated. The most suitable surfactant for the pretreatment stage was found to be NP-series surfactants among 9 kinds of non ionic surfactants. Process parameters such as surfactant concentration, mixing speed, pretreatment temperature and time were tested to optimize for maximum digestibility and 0.5%, 100rpm, 30$^{\circ}C$, and 1 h were found to be optimum, respectively. In order to maximize digestibility, substrate was pretreated with NP-20 and then the pretreated substrate was hydrolyzed by adding TW-80. The effect of surfactant on the hydrolysis of previously surfactant-pretreated newspaper was marginal. Therefore, the digestibility with the addition order of enzyme and surfactant was investigated by using surfactant only in hydrolysis stage. The results show that digestibility was more lowered as the surfactant addition after adding enzyme to substrate was more delayed.

• Korean Chemical Engineering Research
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• v.47 no.1
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• pp.38-45
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• 2009

In this study, interfacial properties were measured for imidazoline type cationic surfactant system which has been widely used as a fabric softener, a dispersant, an anti-static agent, a bleach activator, and an emulsifier. The CMC of imidazoline surfactant was near $6{\times}10^{-5}mol/L$ and the surface tension at CMC was about 32 mN/m. It was found that surface tension was not affected by surfactant concentration but decreased with an increase in pH. The interfacial tension between 1 wt% aqueous solution and n-dodecane was shown to be about 0.01 mN/m and equilibration time was not affected by pH. Phase behavior experiment in a binary aqueous surfactant system showed that only micellar solution of $L_1$ phase was found under conditions of temperature and pH investigated during this study. Only a two-phase region consisting of lower-phase microemulsion in equilibrium with excess oil phase existed under the same conditions, when oil was added to the binary surfactant system. The foam stability measured with 1 wt% surfactant solution increased with pH, which is consistent with surface tension measurement result. QCM(quartz crystal microbalance) measurement showed that surfactant adsorption increased with surfactant concentration but decreased with pH. According to the friction measurement, best fabric softening effect by imidazoline surfactant system was found under alkali conditions.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.799-805
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• 2008

In general, anionic and cationic surfactants are incompatible because their mixtures form insoluble complexes and precipitate in the water. There are, however, some equimolar complexes of anionic and cationic surfactant that are soluble and behave like regular surfactants, specifically like nonionic surfactants, thus named pseudo-nonionic surfactant complexes. Pseudo-nonionic complexes are more effective and efficient in surface activities than their ionic surfactant components as shown by their equilibrium and dynamic surface tensions. They pack at the interface more than their ionic components. When a novel cationic surfactant, diglyceryl dodecyl dimethyl ammonium chloride(DGDAC), having the polyhydroxyl group at the hydrophilic head group, was mixed with a conventional anionic surfactant (sodium dodecyl sulfate; SDS) at equimolar ratio, we found that the aqueous equimolar mixture showed strong positive synergism in which molecular interaction parameter ${\beta}^M$ was very low, -17.2. According to the studies of equilibrium phase behavior and microscopy, this mixed system could form homogenous solutions containing vesicles.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.103.1-103.1
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• 2011

실리콘 이종접합 태양전지에서 계면 결함 밀도는 효율을 결정하는데 가장 중요한 요인으로 작용한다. 계면 결함은 캐리어의 재결합 위치로 작용하여, 계면 결함 밀도가 증가하면 재결합 속도가 증가하게 된다. 흡수층으로 사용되는 실리콘 웨이퍼 (결정질 실리콘)를 가능한 깨끗하게 세정함으로써, 또한 emitter로 쓰이는 비정질 실리콘을 낮은 데미지로 증착하여 계면 결함 밀도를 감소 시킬 수 있다. 이러한 계면 결함 밀도의 감소가 어떠한 변화로 인해 태양전지 특성에 영향을 주는지 시물레이션을 통해 알아보았다. n-type 웨이퍼에 p-type 비정질 실리콘을 emitter로 하여 TCO/p/i/n-type wafer/i/n/TCO/metal의 구조를 적용했고, wafer 전면과 i로 쓰인 무첨가된 비정질 실리콘 간의 계면 결함 밀도를 변수로 적용했다. 그 결과, 계면 결함 밀도가 감소함에 따라 재결합이 감소하여 태양전지 특성이 증가하는 측면도 있지만, 흡수층의 장벽 (barrier height)이 높아져 재결합을 더욱 감소시킴으로 인해 태양전지 특성이 증가함을 알 수 있었다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.1
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• pp.116-122
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• 1988

Interfacial shear stresses have been determined for countercurrent stratified flow of air and water in a nearly-horizontal rectangular channel, based upon measurements of pressure drop, gas velocity profiles and mean film thickness. A dimensionless correlation for the interfacial friction factor has been developed as a function of the gas and liquid Reynolds numbers. Equivalent surface roughnesses for the interfacial friction factor have been calculated using the Nikuradse correlation and have been compared with the intensity of the wave height fluctuation on the interface. The results show that the interfacial shear stress is mainly affected by turbulent mixing near the interface due to the wave motion rather than by the roughened surface.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.217-219
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• 2006

본 논문은 초고압용 XLPE 케이블의 절연/단도전의 계면특성 향상을 위해 계면활성제 부가를 통한 절연파괴전압 향상에 관한 것으로, 계면구조의 변화와 이에 따른 절연파괴전압의 상관성을 밝히고자 하였다. 이를 위해, 계면확성제의 함량에 따른 절연/반도전 계면에서의 결정 미세구조(라멜라 밀도와 분자배향)를 스침각 X-ray와 TEM분석을 통해 밝히고, 이를 절연파괴 특성과의 상관성을 밝혔다. 연구결과, 사용되는 기저고분자와 첨가제 간의 정합성과 최적의 첨가제 함량이 절연재료의 파괴강도에 큰 영향이 있음을 알 수 있었다. 즉, 과도한 첨가제의 부가로 인하여 계면으로 이동한 계면활성제 간에 인력으로 뭉치게 되고(aggregation), 결국 국부적인 도메인을 형성하여 절연파괴 개시부로 작용할 수 있게 된다. 이를 스침각 X-ray (Gl-SAXS)를 통하여 라멜라 밀도 및 배향을 정량화 할 수 있으며, 이는 XLPE 전력케이블의 반도전 재료의 처방 및 계면특성 정량화 기법으로 유효하게 사용될 수 있을 것이다.