• Tribology and Lubricants
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• 제11권5호
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• pp.144-149
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• 1995

Use of high-quality basestocks is increasing to produce high-performance lubricants. However, their tribological characteristics have not been understood clearly yet. In this study, a newly developed basestock from a fuel hydrocracker and a poly-alpha-olefin are selected and investigated on the properties of lubricants formulated with them. The Lubricants are prepared by blending the basestocks with typical additives such as a zinc dialkyldithiophosphate, a dispersant, a detergent and a dispersant-inhibitor package. Frictional and wear-preventing properties are investigated using an oscillating-type wear-testing machine. The contact is a ball-on-disk mode and the testing temperature is varied from room temperature to 200$^{\circ}$C. The results show that their frictional property is varied significantly and that the non-conventional oils result in lower friction and lower wear compared with conventional lubricants, especially at the higher temperatures.

• 한국안전학회지
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• 제18권3호
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• pp.94-100
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• 2003

Gel-like compounds containing flammable solvents were prepared to use fur cleaning agents in field of innovative industries and general purposes. And experiments were conducted to improve the defects of liquified flammable solvents from the view point of safety and health hazards. Flammable solvents used in this study were several single component flammable solvents(turpentine oil, N-methyl-2-pyrrolidone(NMP), d-limonene) and multi component flammable solvent(gasoline and ethanol). For gelation of flammable solvents, commercially Known as Aerosil(equation omitted) 200 fumed silica and triethanolamine(TEA) were used as gelation agent dispersant. The analyses on properties of gel-like compounds was studied by gelation and viscosity test pH test, volatility test and differential scanning calorimetry(DSC) measurement. The experimental results indicate that gel-like compounds containing flammable solvents have pH stability, high viscosity, volatile organic compounds(VOC) control by the decrease of volatility and odor component generation, fluidity control etc. From the experimental values, it can be predicted that the safety in the working place is improved by manufacturing flammable solvents into gel-like compounds.

• 한국가시화정보학회지
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• 제20권3호
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• pp.10-18
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• 2022

We present an experimental investigation on emulsions created during the impact process between a surfactant-laden droplet and an oil layer on water. By varying the surfactant concentration and the viscosity of oil layer, we created emulsions and visualized them using multi-dimensional high-speed imaging. Our analysis shows that the emulsions are more likely to be unstable and decay within a minute if the impacting droplet contains more surfactant. We also found that there are three mechanisms of generation of emulsions depending on the concentration of surfactant and the viscosity of oil layer; the jet pinch-off, cavity pinch-off, and tearing of oil layer. Jet and cavity pinch-off turned out to be dominant mechanisms for high oil viscosities, while tearing of oil layer is dominant for low oil viscosities. Our result is potentially useful in designing optimal dispersant properties for offshore oil contamination.

• 한국안전학회지
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• 제30권6호
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• pp.148-155
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• 2015

Using dispersants is known to be an effective solution to accelerate the natural dispersion and being an appropriate oil spill response strategy. By breaking up large oil chunks into small droplets, dispersants are generally intended to help reducing further oil exposures and slicks. Collecting property data of circulating crude oil in South Korea and understanding the interaction between crude oils and dispersions need to be preceded for the effective dispersant use. This paper provides an property analysis of three selected oils which have the same composition of spilt oils from the Herbei Spirit Incident and conducts an emulsification and toxicity experiment with selected domestic and foreign dispersants. Results will present a direction of future domestic dispersants' development which aimed at eco-friendly and safety.

• 미생물학회지
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• 제33권2호
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• pp.157-162
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• 1997

최근 유류에 오염된 환경을 회복시키기 위하여 생물정화 방법이 널리 이용되고 있다. 따라서 유류오염 환경을 처리하기 위한 생물정화용 생물제제가 보편화되면서 외국으로부터 많은 제품이 국내로 유입되고 있다. 그러나 국내에는 이와 같은 제품의 규격기준이나 표준 실험방법이 체계화되어 있지 않고 또한 효용성에 대한 실제 실험결과가 없는 상태이다. 그러므로 본 실험에서는 일부 유류처리용 생물제제 5종을 대상으로 유류분해율에 대한 실험을 수행하였다. 실험결과 대부분의 제품들은 함유된 화학유분산제에 의해 유류분산능을 나타내었고 유류분해율은 매우 낮은 것으로 나타났다. 일부제품(D)의 경우에는 해수에 분포되어 있는 토착 유류분해세균의 유류분해도를 오히려 저해하는 결과를 나타내었다. 이와 같은 실험의 결과로 미루어 향후 생물정화용 제제의 규격기준 및 표준 실험방법을 국내에도 확립할 필요가 있고, 그러므로서 효율적인 생물정화 기술방법 사용이 활성화될 수 있을 것이다.

• 산업기술연구
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• 제7권
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• pp.27-47
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• 1987

Fine anthracite is very difficult to upgrade by conventional processes such as gravity concentration or froth flotation, because large quantities of fine coals are generated at the mining and preparation stages and a significant portion of these fine coals are mixed with gangue minerals. This study, therefore, was carried out for the purpose of improving recovery of low ash clean coal, effective beneficiation of low-grade coking coal and removal of sulphur from high-sulphur coals by employing the method of selective agglomeration using oil or polystrene flocculants, for coals which are generally hydrophobic in nature will be extracted by using flocculants. Studies were performed by varying solid concentration, concetration of bridging liquid, mixing speed and mixing time, balling speed and balling time, dispersant dosage, flocculant dosage, pulp pH, and particle size. The results were : when the methods of the oil agglomeration and selective flocculation were employ(in the two process the sample was ground to the size of -74 micron), 1) ash content of the agglomerated coal was 9.85, 7.83%, 2) combustibel recovery of it was 98.5%, 93.5%, respectively. It was observed in selective flocculation that polystyrene is an effective flocculant for coal, De-entrapment of shale from the concentrate flocculated by mechanical agitation was necessary for substantional reductions in final ash content.

• 한국재료학회지
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• 제19권3호
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• pp.156-162
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• 2009

Lubricant-based nanofluids were prepared by dispersing carbon nanoparticles in gear oil. In this study, the effects of the particle size, shape and dispersity of the particles on the tribological properties of nanofluids were investigated. Dispersion experiments were conducted with a high-speed bead mill and an ultrasonic homogenizer, and the surfaces of the nanoparticles were simultaneously modified with several dispersants. The effective thermal conductivity of the nanofluids was measured by the transient hot-wire method, and the tribological behaviors of the nanofluids were also investigated with a disk-on-disk tribo-tester. The results of this study clearly showed that the combination of the nanoparticles, the deagglomeration process, the dispersant and the dispersion solvent is very important for the dispersity and tribological properties of nanofluids. Lubricant-based nanofluids showed relatively low thermal conductivity enhancement, but they were highly effective in decreasing the frictional heat that was generated. For nanofluids containing 0.1vol.% graphite particles in an oil lubricant, The friction coefficient in the boundary and fluid lubrication range was reduced to approximately 70% of the original value of pure lubricant.

• KSBB Journal
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• 제7권2호
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• pp.107-111
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• 1992

Candida bombiocola에서 생성된 sophorolipid의 응용성을 조사하기위하여 유류분산능력 및 세제, 분산제로서의 특성을 살펴보았다. 1%미만의 sophorolipid용액이 높은 온도($70^{\circ}C$)에서 유류분산 및 제거에 좋은 효과를 보였다. Sophorolipid용액은 낮은 표면장력에서도 거품이 형성되지않는 특성을 가졌으나, 옷감에 대한 세척력 및 보습력은 낮은 것으로 밝혀졌다. 기존의 다른 화학분산제에 비해 분산력 및 안정성이 특히 높은 것으로 관찰되었다.

• Composites Research
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• 제30권1호
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• pp.41-45
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• 2017

Magnetite nanoparticles were synthesized by adding an ammonium hydroxide to a mixed solution of iron (II) and (III) chlorides. A silicon surfactant of ${\alpha},{\omega}$-(3-aminopropyl)polydimethylsiloxane was adsorbed on the particles as dispersant and a polydimethylsiloxane polymer was used to prepare ferrofluids of silicone oil base. Fluorinated surfactants of anionic ammoniated perfluoroalkyl sulfonamide and nonionic fluoroaliphatic polymeric esters were applied to the particles and a perfluoropolyether was used to prepare ferrofluids of fluorine oil base. The experimental conditions were used for preparing the ferrofluids with concentrations of 200, 300 and 400 mg/mL, and density, magnetization and viscosity of the products were characterized. The density values increased in proportion to the concentration, indicating 1.11-1.27 g/mL for silicone-oil-based fluids and 1.95-2.10 g/mL for fluorine-oil-based fluids in the range of 200-400 mg/mL. The saturation magnetization of the silicone-oil-based and fluorine-oil-based fluids indicated 14.7, 24.4, and 30.7 mT and 15.8, 23.3, and 33.7 mT for 200, 300, and 400 mg/mL, respectively, depending on the content of magnetic particles in the fluid. The viscosity of the silicone-oil-based ferrofluids was highly stable compared to that of the fluorine-oil-based with increasing temperatures. The ferrofluids are usually applied to seals and speakers with the silicone base and to seals with the fluorine base.

• 대한환경공학회지
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• 제22권4호
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• pp.679-688
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• 2000

최근 해상유류오염사고시 사용되는 유화제는 해안으로 이동하여 또 다른 수질오염의 원인으로 문제가 되고 있다. 이 연구에서는 자성을 띠고 있는 흡착제를 이용하여 해수 속에 잔류하는 유화제를 제거하는 기술에 대해서 논의하였다. 본 실험에서는 자성을 띠는 흡착제로서 마그네타이트와 마그헤마이트를 이용하였고, 대표적인 유화제 성분으로는 음이온성 계면활성제인 SDDBS (Sodium dodecylbenzene sulfonic acid)와 비이온성 계면활성제인 Triton X-100 (t-octylphenoxypoly-ethoxyethanol)을 사용하였다. 실험은 두 흡착제의 유화제에 대한 흡착 평형시간과 흡착능에 대한 회분식 실험과 모의 실제 상황에서 흡착제가 영구자석이나 전자석에 의해 수거되는 양상을 알아보기 위한 수조실험으로 나누어 이루어졌다. 마그헤마이트는 계면활성제의 종류와 사용된 물의 종류에 상관없이 제거효율이 일정하게 나타나는데 비해 마그네타이트는 음이온성 계면활성제에 대해 선택적으로 고효율을 보이고 있고, 이온이 존재하는 해수보다는 증류수의 경우가 높은 효율을 보이고 있다. 미그네타이트의 흡착메커니즘은 정전기적 인력에 의한 것으로 판단되고, 마그헤마이트의 경우는 정전기적 인력과 함께 흡착능을 향상시키는 구조적 특정과 표면상태의 특성으로 설명되어진다. 수조실험에서는 흡착이 이루어진 후 자석에 의한 회수는 100%에 가까운 것으로 나타났다. 이와 같은 결과는 두 흡착제와 사석에 의한 유화제 제거방법이 실제 해상에서 적용되었을 때 유화제를 짧은 시간 내에 고효율로 처리할 수 있는 효과적인 방법임을 시사한다.