• 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.

• Clean Technology
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• v.19 no.1
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• pp.8-12
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• 2013

Phase behavior of carbon dioxide + surfactant binary system and carbon dioxide + surfactant + water ternary system was investigated at the temperatures from 318 K to 348 K by using high pressure vapor liquid equilibrium apparatus containing variable-volume view cell. Sorbitan monopalmitate was used as the surfactant. The cloud point pressures for the binary mixture of carbon dioxide + sorbitan monopalmitate increased with an increasing of system temperatures and the maximum cloud point pressure was observed at the composition of 0.226 wt% of sorbitan monopalmitate. On the other hand, as the temperatures and compositions of water increased, the cloud point pressures for ternary system containing 0.1 wt% of sorbitan monopalmitate increased significantly. For the ternary system of constant 0.2 wt% of water, the cloud point pressure curves show relatively flat according to the change of compositions of surfactant. The cloud point pressures increased when the temperatures and compositions of water increased.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2B
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• pp.207-212
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• 2009

Surfactants were used as representative anionic and non ionic surfactants to investigate the effect of mass transfer on the mineral-catalyzed Fenton-like oxidation of sorbed phenanthrene. Mass transfer of phenanthrene on the oxide surface or interlayer between aqueous and solid phases was generated by surfactant addition. Apparent solubility of phenanthrene was increased as surfactant concentration increasesd. In tests using Tween 80, oxidation of phenanthrene decreased as apparent solubility increased. High apparent solubility was not responsible for oxidation of sorbed phenanthrene in the sand due to the surfactant acted as a scavenger of degradation. In tests with SDS, $H_{2}O_{2}$ decomposition rate in Fenton-like oxidation was decreased by complexation between goethite and SDS. However, in tests using 32 mM of SDS, efficiency of phenanthrene treatment increased compared to the test without SDS addition. Therefore, suitable amount of SDS addition could provide optimum condition for phenanthrene oxidation on the oxide surface or interlayer between aqueous and solid phase, and decrease $H_{2}O_{2}$ decomposition, and as a result, phenanthrene removal efficiency can be improved.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.112-117
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• 1999

The pulsed field gradient NMR method has been used to determine self-diffusion coefficients in ternary N-alkyl-N, N-dimethylamine oxide/hydrocarbon/$D_2O$ system. For n = 12, 14, 16 and n' = 8, 10, 12, 14, 16, in the micellar phase, diffusion is chiefly governed by the hydrodynamic transport of micelles, supplemented by an exchange of solubilized hydrocarbon upon micellar collisions. This investgation is performed by variations in both the surfactant alkyl chain length and in the size of the hydrocarbon molecules. In cubic phases, the solvent still exhibits values of the diffusion coefficients which are typical for motion in a continuous water phase, with the microemulsion droplets acting as obstacle. Mobilities of the surfactant in the gel state were low and have been determined only for the surfactant($C_{12}DMAO$) with the shortest alkyl chain length. Exchange of hydrocarbon between micellar entities in the gel was found to be occured by a hopping process, the associated rate decreased with alkyl chain length of the surfactant.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.35.2-35.2
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• 2009

최근 본 연구실에서 무연 솔더를 위한 새로운 Cu-Zn 합금 젖음층을 개발하였다. 전해도금을 통하여 Cu-Zn 합금층을 형성한 뒤 그 위에 Sn-4.0wt% Ag-0.5wt% Cu (SAC 405) 솔더를 리플로 솔더링을 통해 솔더접합부를 형성하였으며 계면에서 생성된 금속간 화합물의 형성 및 성장 거동을 연구하였다. SAC/Cu 시스템의 경우, $150^{\circ}C$에서 시효 처리를 실시하는 동안 솔더와 도금된 Cu 계면에서 $Cu_6Sn_5$ 상과 미세한 공공이 형성된 $Cu_3Sn$ 상이 발견되었다. 반면에 SAC/Cu-Zn 시스템에서는 계면에서 $Cu_6Sn_5$ 상만이 형성되었다. 또한 큰 판상형의 $Ag_3Sn$ 상이 SAC/Cu 시스템에 비해 현저하게 억제되었다. SAC/Cu-Zn 계면에서의 금속간 화합물의 성장 속도가 SAC/Cu 계면에서 형성된 금속간 화합물의 성장 속도보다 느리게 나타났다. Cu-Zn 젖음층의 Zn가 솔더와 Cu-Zn 층 사이에서 Cu와 Sn 원자의 상호 확산을 방해하기 때문이다. 본 연구에서는 Cu와 Cu-Zn 층을 이용한 솔더 접합부의 낙하 충격 신뢰성을 연구하였다. 낙하 충격 시험 시편은 두 개의 인쇄 회로 기판을 SAC 405 솔더볼을 이용하여 리플로를 통해 상호연결 하여 제조되었다. 이 때, 각각의 인쇄 회로 기판의 패드에는 Cu 층과 Cu-Zn층을 전해도금을 통하여 각각 $10{\mu}m$두께의 젖음층을 형성하였다. 낙하 시험 시편을 제조한 뒤, 시효 처리에 대한 낙하 저항 신뢰성의 특성을 연구하기 위해 250, 500 시간동안 시효처리를 한 후 각 조건에서 계면에 형성된 금속간 화합물의 성장 거동을 관찰하였으며, 낙하 충격 시험을 실시하였다. 낙하 시험은 daisy chain으로 연결된 시편의 저항이 100 Ohm 이상 측정되었을 때 중단되도록 하였다. Cu-Zn/SAC/Cu-Zn 시편의 경우 초기 리플로를 하였을 때 불량이 발생하는 평균 낙하 수는 350이며, Cu/SAC/Cu 시편의 평균 낙하수는 200 미만으로 나타났다. Cu/SAC/Cu 시편의 경우, 시효처리 시간이 증가함에 따라 평균 낙하수는 큰 폭으로 감소하였지만, Cu-Zn/SAC/Cu-Zn 시편은 불량이 발생하는 평균 낙하수의 감소폭이 보다 완만하게 나타났다. Cu 층에 Zn를 첨가함으로써 솔더와 젖음층 사이에서 형성된 금속간 화합물의 성장 및 미세 공공의 형성이 억제되었고, 솔더 접합부의 과냉을 감소시킴으로써 큰 판상형의 $Ag_3Sn$ 상의 형성을 억제함으로써 Cu-Zn/SAC/Cu-Zn 솔더 접합부에서 Cu/SAC/Cu 솔더 접합부보다 낙하 충격에 대한 저항성 및 신뢰성이 향상되었다. 이는 무연 솔더에 Zn를 첨가하여 낙하 충격 신뢰성을 향상시킨 것과 동일한 효과를 나타냈음을 확인하였다. 본 연구는 한국 과학 기술 재단의 전자패키지 재료 연구 센터(CEPM)와 지식 경제부의 부품 소재 기술 개발 사업의 지원을 받아 수행되었습니다.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.26 no.1
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• pp.93-106
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• 2000

One phase liquid crystal formula was developed by using of nonionic surfactants, polyols, water and oils and its physical property was investigated. At the system oft to 1 ratio of POE octyldodecyl ether series, which have Y type (branch type) hydrophobic group, and POE glyceryl monostearate series, Y type hydrophilic group, it was examined that the formula at 7:3, 6:4, and 5:5 ratio of nonionic surfactant : polyols, shows L$\alpha$ , a pattern which is a typical characteristic of liquid crystal structure under the cross microscope polarized film. As results of L$\alpha$ phase diagram study, the formula which had high hydrophilic nonionic surfactant and the 7:3 ratio of nonionic surfactant : polyol appeared to increase the amount of oil containment and to be capable of the lamella formation. Besides it was examined that lamellar liquid crystal formula could contain about 25-40% water between lamella layers and it was transformed into w/o emulsion following as water content increased. When the lamella gel was applied into a human skin, it was investigated that it had effectiveness in increasing transepidermal water content of the skin.

• Korean Journal of Materials Research
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• v.7 no.7
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• pp.582-586
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• 1997

본 연구에서는 플라즈마 화학 증착법으로 기판에 따른 DLC 박막의 접착력 변화를 조사하였다. 박막의 분리가 발생하기 시작하는 경우의 두께를 임계두께로 정하여 스크래치 테스터로 측정된 임계하중과 더불어 박막의 잡착강도값으로 사용하였다. 다이아몬드상 탄소박막은 실리콘 기판에서 가장 우수한 접착력을 가지는 것으로 나타났으며, 크롬>티타늄>철>세라믹 기판의 순으로 접착력이 감소하였다. XPS, AES 분석을 사용하여 계면에서 결합구조와 결합형태 등을 관찰하여 접착력과의 관계를 조사하였다. 그 결과 다이아몬드상 탄소박막의 접착강도는 막/기판의 계면에서의 탄화물 형성에 영향을 받으며, 계면에서의 초기산화물층에 큰 영향을 받는것을 확인하였다.

• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.330-333
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• 2001

일반적으로 하나 또는 그 이상의 입자상 충전재 흑은 섬유상 강화재와 연속상인 고분자 기재로 이루어진 고분자 복합재료는 물성이나 기능이 더욱 더 우수한 고성능/고기능성 고분자 재료에 대한 수요가 급격히 증대됨에 따라 이에 대한 많은 연구가 행해지고 있다[1,2]. 그러나 고분자 복합재료의 응력전달은 강화재와 고분자 기재의 계면을 통하여 일어나게 되므로 복합재료의 기계적 물성 등은 충전재의 양, 입자의 크기, 표면성질 뿐만 아니라 강화재와 고분자 기재 사이의 계면 접착력 또는 계면 성질에 크게 좌우된다. (중략)

• Proceedings of the Korean Fiber Society Conference
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• 2001.10a
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• pp.448-451
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• 2001

각각 소수성과 친수성을 나타내는 올레핀계 고분자인 PE 와 granule starch의 blend는 서로 다른 특성에 기인하여 거시적인 상분리 현상이 발현되며 두 물질간에 계면을 형성한다. 이와 같이 낮은 interfacial adhesion을 갖는 내부 구조는 외력에 대한 저항력이 급격히 저하되어 낮은 물성 특성을 나타낸다. (중략)

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.620-625
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• 2018

Liquid detergent based on sodium lauryl ethoxy sulfate (SLES) as main ingredient sometimes met gelling film on the surface when it is opened in the air. It was assumed because of the change of phase diagram of micelle by concentration change of surfactant, major ingredient of detergent when the water of detergent is evaporated. SLES showed strong hexagonal liquid crystal (LC) in 30~60 wt%, and lamellar LC over 60 wt%. In this research surface gelling formation of liquid detergent which is based on SLES as main ingredient was because of water evaporation. As water of detergent was evaporated, concentration of surfactant became higher. It was checked that surface gelling was LC of mixed surfactant system. Conclusionally we applied alpha olefin sulfonate (AOS) having good solubility, Sodium secondary alkane sulfonate (SAS) preventing hexagonal LC and hydrotrope sodium xylene sulfonate (SXS) and PEG1500 in order to prevent gelling film in SLES based liquid detergent. Like this, improved formula 4 and 5 can prevent the formation of gelling film on the surface of liquid detergent when it is opened in the air.