• 설비공학논문집
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• 제14권4호
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• pp.285-292
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• 2002

The vapor pressure and miscibility measurement apparatus was developed and used to obtain data for refrigerant/oil mixture. The vapor pressure and miscibility data for R-404A/32 ISO VG polyol ester (POE) oil mixture and R-404A/46 ISO VG polyol ester oil mixture are obtained over the temperature range from -20 to $60^{\circ}$ with at $10^{\circ}$ intervals and the oil concentration range from 0 to 70 wt%. Using the experimental data, an empirical model was developed to predict the temperature vapor pressure-concentration relations for R-404A/46 ISO VG polyol ester oil mixtures at equilibrium. In the R-404A/32 ISO VG polyol ester oil mixture, the average root-mean-square deviation between measured data and calculated results from the empirical model is 1.24% and in the R-404A/46 ISO VG polyol ester oil mixture, that is 1.37%. Miscibility for R-404A/32 ISO VG polyol ester oil mixture was observed all over the experimental conditions. Immiscibility for R-404A/So1est 46 oil mixture was observed at the low oil concentrations (20~30 wt%) over the high experimental temperature range (50~$60^{\circ}$).

• Tribology and Lubricants
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• 제36권3호
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• pp.139-146
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• 2020

Global warming has led to an increase in demand of eco-friendly vehicles, such as electric cars, for reducing greenhouse gas emissions, and especially, regulating carbon dioxide generation. In addition, electric vehicles are equipped with an electric drive-type hermetic scroll compressor and a refrigerant, which exhibit current and future trends of using environmentally friendly refrigerants, including R-1234yf. In this study, polyol ester-based refrigeration oils are prepared via condensation esterification of polyol and fatty acids. The oils can be combined with R-1234yf refrigerant for applications in air conditioning and cooling systems of electric vehicles. The structure of synthetic polyol esters is confirmed via ¹H-NMR and FT-IR spectrum analysis, and the composition of the polyol ester is analyzed via gas chromatogram analysis. Furthermore, kinematic viscosity, viscosity index, total acid value, pour point, and color are analyzed as fundamental physical properties of the synthetic polyol esters. The compatibility and chemical stability of the synthetic polyol ester combined with the R-1234yf refrigerant are obtained via high temperature and high pressure oil-resistant refrigerant tests. The changes in the oil color and catalyst activity are observed before and after the experiment to determine whether it is suitable as a refrigerator oil.

• KSBB Journal
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• 제20권2호
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• pp.84-87
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• 2005

바이오디젤과 바이오디젤을 기반으로 생산된 neopentyl polyol ester (NPE)계 윤활유 베이스, 디젤유 윤활유와 석유디젤을 분석대상으로 하여 지렁이 (Eisenia fetida)를 이용한 독성 시험을 수행하였다. OECD 207규격에 근거하여 독성을 분석한 결과 바이오디젤과 NPE계 윤활유 베이스의 반수치사농도 $(LC_{50})$ 값은 각각 2,450과 1,528 mg/kg dry weight of soil로서 두 물질은 독성 이 적은 경독성 (slightly toxic) 물질인 것으로 판명되었다. 디젤유 윤활유와 석유디젤의 경우 반수치사농도 $(LC_{50})$ 값이 각각 500과 603 mg/kg로서 중등독성 (moderately toxic) 물질로 판정되었다.

• KSBB Journal
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• 제20권1호
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• pp.55-59
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• 2005

바이오디젤과 바이오디젤을 기반으로 생산된 neopentyl polyol ester (NPE)계 윤활유 베이스, 디젤유 윤활유와 석유디젤을 분석대상으로 하여 독성을 평가하였다 조류를 이용하여 수용액 상에서 화학물질의 독성시험을 조사하는 OECD 201에 근거하여 Chlorella vulgaris를 96시간 동안 배양하면서 독성시험 분석한 결과, 바이오디젤과 NPE계 윤활유 베이스의 반수저해농도 $(EC_{50})$ 값은 각각 84와 69mg/L로서 두 물질이 독성 이 적은 경독성 (slightly toxic)물질인 것으로 판명되었다. 디젤유 윤활유와 석유디젤의 경우 반수저해농도 $(EC_{50})$ 값이 각각 42와 24 mg/L로서 중등독성 (moderately toxic) 물질로 판정 되었다.

• Tribology and Lubricants
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• 제17권2호
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• pp.109-115
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• 2001

The lubricating performance of 23 kinds of polyol ester base oils 〔POEs〕 having different branch shapes was investigated by using a four ball tribometer under boundary lubrication condition. All the polyol ester base oils used in this study were made up of polyhydric alcohols of two-four valence and normal or branched fatty acids of different carbon number. The wear characteristics of polyol ester base oils are different from those of mineral oil, strongly affected by the branch shapes of fatty acids in their molecles. In particular, the polyol ester base oils having normal fatty acids such as n-octanoic acid, n-nonanoic acid etc. show much better wear performance than POEs having branched fatty acids such as 2-ethylhexanoic acid, 3,5,5-trimethyl hexanoic acid, etc. As the carbon chain length of normal fatty acids, in case of POEs of normal fatty acids, is increased, their wear rate is decreased and, in case of POEs of branched fatty acids, as the degree of branch of branched fatty acids is decreased, their wear rate is decreased. All the wear results of polyol ester base oils could be reasonably explained by comparing cohesive ability among fatty acid molecules in adsorption film by fatty acids obtained as POEs were decomposed.

• 한국응용과학기술학회지
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• 제26권2호
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• pp.213-223
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• 2009

Conventional additives were added to a newly synthesized base oil to create synthetic lubricants. Commercial polyol ester prepared in this laboratory were obtained as esterification of 1,1,1-trimethylol propane and respectively. This newly synthesized base oil had a variable chemical structure that could achieved the following properties; oxidation or thermal stability, low temperature fluidity, and higher flash points. When compared with commercial mineral lubricants, the synthetic lubricants show superior thermal and oxidation stability, and anti-wear properties.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.149-155
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• 2001

New semi-fluorinated polyol esters were synthesized by condensation reaction of polyols (NPG and TMP) and carboxylic acids such as 2-ethylhexanoic acid, stearic acid and perfluorooctanoic acid. The structures of polyol esters were confirmed by FT-IR and H-NMR etc. And, the fluorinated polyol esters were insoluble in several oils, however, the semi-fluorinated polyol esters were soluble in several oils depended on the structure of polyol esters. The physical properties such as 4-ball wear property and extreme-pressure (EP) properties were characterized by measuring wear scar diameter through ASTM D2266 and by determining the load-carrying through ASTM D2783 method, respectively. As the results, wear scar diameters of oils in which the semi-fluorinated polyol esters were added were not changed compared to those of not added oils. While extreme-pressure properties remarkably Increased with fluorine contents of the esters depended on the structure of acid moiety and polyol moiety. Also, the extreme-pressure property of semi-fluorinated NPG polyol ester in gasoline engine oil was better than that of commercial Teflon coating additive.

• 설비공학논문집
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• 제8권4호
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• pp.473-483
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• 1996

To protect the ozone layer, R22 will be replaced with HFCs. R407C is a leading candidate as alternative refrigerant for air conditioner due to its similar thermodynamic characteristics with R22. In replacing R22 with R407C, the compatibility with lubricating oil is of major concern. Polyol ester (POE) oil among the synthetic oils is considered to be the best lubricant for use with R407C because of good electrical properties and miscibility. However, lubricating ability of mixture of R407C/POE oil is lower than that of R22/mineral oil due to the production of acid by hydrolysis which causes corrosive wear. Therefore, to minimize water content, it is needed to develop a molecular sieve desiccant which is compatible with R407C and ester oil. This paper discusses (1) the change of properties of POE oil when current molecular seive is used, (2) the effects of POE oils and additives on durability of compressor. Through compressor life test and bench wear test, it was found that inadequate use of POE oils and additives may promote the deteriation of molecular sieve, resulting in decrease of durability of compressor.

• 대한화장품학회지
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• 제18권1호
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• pp.132-149
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• 1992

이 논문은 외관, 안정도, 얇고 균일하게 끈적이지 않는 Film 형성 등의 우수한 특징을 갖고 있기 때문에 Cosmetic preparations의 여러 방면에 응용하고 있는 Microemulsion gel에 관한 것이다. 우리의 연구는 Microemulsion의 Clarifying agent 또는 Coupling agent로 이용되고 있는 Polyol류가 Microemulsion에 미치는 영향을 해명함으로써, Consistency, Stability, Clarity, Pick-up from a container등이 우수한 최적의 Microemulsion gel의 형성 조건을 확립하여 Cosmetic preparations에 응용할 수 있도록 하는 것이다. 연구한 System은 De-ionized water, Oil로는 Polar한 Ester oil, Emulsifying agent는 Nonionic syrfactant, Coupling agent는 Polyol로 구성하였으며, Three component phase diagram과 Tetrahedral phase diagram을 이용하여, Polyol의 비율에 따라 Microemulsion gel의 투명 영역, Consistency, 충격에 의한 Resonance 효과, Pick-up from a container등의 변화를 고찰하였다. 연구결과 구성 성분 중 De-ionized water의 Coupling agent의 비율변화에 의한 영향이 가장 크게 나타났으며, Coupling agent로 사용된 Glycerine의 물에 대한 비율이 63-75%일 때 최적 Microemulsion gel 형성 영역이 가장 넓게 나타났다. 특히 Polyol의 비율을 적절히 선택함으로써, 최근 관심이 모아지고 있는 최소의 유화제량으로 최대의 유상량을 함유한 Microemulsion gel을 얻는데 기여할 수 있을 것으로 생각된다.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.309-310
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• 2002

A minimal quantity lubrication (MQL) machining is able to achieve both functions of cooling and lubrication with an extremely low quantity of a cutting fluid and a large amount of air blow. Using a biodegradable ester oil, turning tests were carried out to evaluate the effectiveness of the MQL system. It was found that the performance of MQL cutting was equivalent to, or better than, that of conventional cutting, because the MQL system tends to prevent the heat damage of the tool tip and, if an effective lubricant such as a particular polyol ester is applied to the system, it can avoid the extensive transfer of workpiece materials on to the tool surface.