• Journal of Electrical Engineering and Technology
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• 제9권2호
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• pp.662-669
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• 2014

Mineral oil has been widely used as dielectric insulating fluid in transformers due to its excellent performance in-service. However, there are few issues with mineral oil such as it has poor biodegradability and could contaminate the environment if a spillage occurs. With the increasing tight regulation on safety and environment, alternative fluids for mineral oil are currently being investigated and among the suitable candidate is the vegetable oil. There are different types of vegetable oils and one of them is the palm based oil. At the moment, extensive research works are carried out to examine its feasibility to be applied in transformers. This paper will review the previous research works that were carried out to examine the suitability of palm based oil as dielectric insulating fluid in transformers. The physical and chemical properties of palm based oil are studied based on viscosity, acidity, oxidation stability and flash point. Next, the electrical characteristics of palm based oil are examined based on AC breakdown voltage, relative permittivity, dissipation factor and partial discharge.

• 자원리싸이클링
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• 제27권2호
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• pp.55-62
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• 2018

식물성 기름을 포수제로 사용하였을 때 바텀애쉬 부유선별의 특성에 대해 알아보고자 본 연구를 실시하였다. 석탄회 부유선별에서 유상 포수제로 사용되는 Kerosene의 첨가량 변화에 따른 실험에서 Kerosene을 9 kg/ton의 비율로 첨가하였을 때, 미연탄소 회수율이 80%, 부유 산물의 미연탄소 함량이 63%인 것으로 나타났다. 부유선별 효율을 향상시키기 위해 식물성 기름인 콩유를 포수제로 사용한 실험에서는 콩유를 9 kg/ton의 비율로 첨가하였을 때, 미연탄소 회수율과 부유 산물의 미연탄소 함량이 각각 95%, 68%로 증가하였다. 콩유보다 이중결합이 있는 폴리 형태의 불포화 지방산이 많이 함유된 홍화씨유를 9 kg/ton의 비율로 첨가하였을 때, 미연탄소 회수율 99%, 부유 산물의 미연탄소 함량은 78%로 나타났다. 부유 산물의 미연탄소 발열량은 5,803 cal/g으로 나타나 화력발전소 에너지 연료로 활용이 가능함을 확인하였다. 최종적으로 식물성 기름을 포수제로 사용하였을 때 광물성 기름인 Kerosene보다 미연탄소 회수율과 부유 산물의 미연탄소 함량이 높은 것으로 나타났다. 또한, 식물성 기름 중 이중 결합이 2개 이상인 폴리형태의 불포화 지방산이 많이 함유된 기름일수록 부유 산물의 미연탄소 함량이 높아 미연탄소에 대한 흡착성이 우수한 것을 알 수 있었다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XIII)
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• pp.434-437
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• 2003

A new bacterial strain, was isolated from activated sludge, identified and named P. aeruginosa EMS1. The new strain produced surface-active rhamnolipids by batch cultivation in mineral salts medium with waste flying oils. The mutant strain KH7, designated P. aeruginosa EMS1, derived by random mutagenesis with N-methyl-N-nitro-N-nitrosogoanidine treatment producing high levels of the biosurfactants was selected by an ion-pair plate assay. The mutant strain KH7 showed 4-5 times more hydrocarbon emulsification as compared to the parent when grown on waste frying oils and various hydrocarbons. Furthermore, P. aeruginosa EMS1 and mutant strain KH7 was also able to use whey as a co-substrate for growth and biosurfactant production. As results of this study, mutant strain KH7 is a very efficient biosurfactant producer, and its culture conditions are relatively inexpensive and economical. Rhamnolipid is synthesized by the rhlAB-encoded rhamnosyltransferase. To be convinced of these genes, we performed PCR based on P. aeruginosa PAO1 whole-genome database. rhl gene cluster nucleotide and amino acid sequences were compared for both parent and mutant. Comparison of nucleotide sequence of rhlAB, there were usually terminal's codons exchange.

• 공업화학
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• 제9권5호
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• pp.726-728
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• 1998

${\varepsilon}$-caprolactam의 음이온 중합반응을 미네랄 오일의 존재하에서 수행하여 오일함침 나일론 6을 합성하였다. 8 phr 미만의 오일이 첨가되었을 때에는 중합반응속도 및 생성물의 분자량에 큰 변화가 없었다. 오일의 첨가에 의해서 생성물의 신율 및 충격강도는 향상되었으며, 표면경도와 인장강도는 저하되었다. 오일함량이 6 phr인 나일론에서 마찰계수는 최소값을 나타내었으며, 이때의 마찰계수값은 오일이 첨가되지 않은 나일론의 32%에 지나지 않았다.

• Journal of Electrical Engineering and Technology
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• 제11권1호
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• pp.184-191
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• 2016

In recent years, there are a number of studies that have been carried out to explore the alternative for Mineral Oil (MO) as dielectric insulating fluid in transformers due to the increasing tight regulation on safety and environment. Vegetable oils have been identified as suitable candidate since it is biodegradable, non-toxic and high flash/fire points which ensure more in-service safety. Among the types of vegetable oils considered for transformers application are Palm Oil (PO) and Coconut Oil (CO). This paper presents an experimental study on the lightning breakdown voltages of PO and CO under non-uniform electric field based on needle-sphere electrodes configuration at 3 small gap distances. The type of PO used in this study is Refined Bleached and Deodorized Palm Oil (RBDPO) Olein. The main focus of this study is to examine the lightning breakdown performance of RBDPO and CO under different test conditions and assess its suitability as dielectric insulating fluid in transformers. The effect of voltage polarities (positive and negative) and testing methods (rising-voltage, up-and-down and multiple-voltage) were investigated. The data obtained from all tests were analysed by Weibull distribution in order to determine the withstand voltages for each type of oils. It was found that the breakdown voltages of RBDPO and CO are comparable with MO under positive lightning impulse. Under negative lightning impulse, the breakdown voltage of MO is slightly higher than RBDPO and CO. There is no significant effect of testing methods and voltage polarities on lightning breakdown voltages of RBDPO and CO. Based on the statistical analysis, it is found that the breakdown voltages of RBDPO and CO at 1% probability are slightly lower than MO.

• 미생물학회지
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• 제44권1호
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• pp.22-28
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• 2008

본 실험은 생분해가 어려운 절삭유를 단일 균주에 의해 생물학적 처리를 하는 데에 목적이 있다. 절삭유, 절삭폐유로부터 호기 균주 81개를 분리하여 이중 절삭유 분해능이 가장 높은 균주로, 48시간 내에 90.4%를 제거한(초기농도 699.1 mg/L) KS47을 선별하였다. KS47은 형태학적, 생리 화학적, 16S rDNA 염기서열, 그리고 지방산 분석을 통해 Pseudomonas aeruginosa로 동정되었다. P. aeruginosa KS47은 절삭유를 탄소원으로 사용하여 성장 할 수 있었으며, 절삭유 분해시, 최적 분해 조건은 1.5 g/L(wet weight), pH 7.0, $30^{\circ}C$이었다. 최적 조건 하에서 절삭유의 제거능을 본 결과, 1,060 mg/L의 절삭유를 12시간 내에 83.7% 제거함을 확인하였다.

• Tribology and Lubricants
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• 제38권2호
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• pp.41-52
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• 2022

Mineral electrical insulating oil, which is widely used in transformers, exhibits excellent cooling performance and transformer efficiency. However, given that it is composed of petroleum-based components, it is weak in terms of biodegradability. This causes environmental problems in case of leakage and a low flash point, which is a factor that would cause great damage in the event of a fire in a substation. In this context, the use of eco-friendly electric insulating oil composed of bio-based vegetable oil and synthetic ester, which has excellent biodegradability and flame retardancy performance, has recently been expanded to the field of electric power, and various research and development (R&D) studies are in progress. According to different research results, vegetable oil and synthetic ester manufacturing technology, thermal stability, oxidation stability, property change, and quality control, which are characteristics of eco-friendly electrical insulating oils, are major factors affecting the maintenance of insulating oil properties. In addition, power companies have established and operated quality control standards according to the use of eco-friendly electrical insulating oil as they expand the exploitatoin of renewable energy in electricity production. In particular, deterioration and oxidation characteristics were jointly identified in R&D as an important influencing factor according to the content of saturated and unsaturated fatty acids present in vegetable oils and synthetic esters in power transformer applications.

• 공업화학
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• 제29권3호
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• pp.289-297
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• 2018

자동차용 윤활유가 국내 윤활유 시장의 35%를 차지하고 있으며, 이 중 엔진오일이 자동차용 윤활유의 77%를 차지하고 있다. 운전자와 엔진보호를 위해 유통 엔진오일의 품질이 적절하게 관리되어져야 한다. 하지만 KS제품과 합성엔진오일(합성기유가 30% 이상 포함된 제품)은 석유 및 석유대체연료 사업법상 품질검사에서 제외되어져 있다. 본 연구에서는 국내 유통되고 있는 합성엔진오일 30개 제품에 대한 품질 모니터링을 실시하였다. 품질 모니터링 결과, 2개 제품이 품질이 부적합하였는데, 이 중 1개 제품은 해외에서 수입한 합성엔진오일이며, 다른 1개 제품은 KS제품이면서 합성엔진오일이었다. 또한 고온모사증류시험(SIMDIST)을 이용해 엔진오일의 패턴을 분석한 결과, 해외 수입제품 몇 개를 제외하고는 대부분 일반 광유 엔진오일의 전형적인 넓은 탄소수 분포 패턴을 보였다. 따라서 소비자의 피해를 예방하기 위해 KS제품과 합성엔진오일에 대한 적절한 품질관리 법규가 필요한 것으로 판단된다.

• 한국유기농업학회지
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• 제23권2호
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• pp.373-390
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• 2015

This study investigated the effect of coated feed using mixed oil on rumen fermentation characteristics. Two experiments were conducted based on materials that were mixed. First, cashew nut and soybean oils were mixed with white mineral oil. And second, different plant extracts were mixed with white mineral oil. At first experiment, inclusion levels of mixed oil on diet (0.03%, 0.1%, 0.5%) were applied as variables. A coated diet was fermented with rumen inoculum according to in vitro rumen fermentation and its parameters were investigated. In the result of first experiment, no negative effects on rumen pH were found. Significantly decreased dry matter digestibility was detected at 0.5% treatment (P<0.05). Total gas productions in control and 0.03% were significantly greater than those of others (P<0.05). Significantly reduced methane productions were found in all treatments compared to the control (P<0.05). Inclusion of mixed oil did not affect on ammonia production. Total volatile fatty acid production was also not influenced by coating with mixed oils. Rumen fermentation parameters were greatly changed according to introduced plant extracts at second experiment. The significantly lowest and greatest ammonia productions were found at treatments with Ixeris dentata and Plantago asiatica, respectively (P<0.05). The significantly greatest acetate and propionate productions were detected at treatments with Crucuma longa and Zizyphus vulgaris 1, respectively (P<0.05). All treatments, except Chrysanthemum idicum, Euyale ferox seed, Moringa leaf and fruit and Zizyphus vulgaris 1, showed significantly increased total volatile fatty acid production compared to the control (P<0.05). Only Paeonia lactiflora showed significantly lesser gas production than the control (P<0.05). In methane production, Ceramium, Zizyphus, Paeonia, Agrimonia, Torilis, Mugwort, Foeniculum, Euphorbia, Taraxacum, Artemisia, Momordica, Curcuma and Moringa reduced methane significantly compared to the control (P<0.05).

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1672-1677
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• 2003

Carbon dioxide($CO_2$, R-744) has become a very popular issue in application to refrigeration and air conditioning systems as a natural refrigerant. An experimental study has been carried out to investigate the vapor pressure and miscibility of refrigerant R-744 in the presence of lubricant oil. This is of particular interest in the selection of the lubricant oil for the compressor of a refrigeration system or an air conditioning system using the refrigerant R-744. This apparatus consists of the test section, measuring devices, the vacuum pump, the constant temperature bath and relevant connecting pipes made of stainless steel. Two lubricant oils, such as mineral oil(Naphthenic) and polyol ester(POE) oil, are considered in the present study. For this purpose, test runs were conducted with the oil concentration range from 5 to 50 wt%, and the temperature range from -10 to $10^{\circ}C$ with $2^{\circ}C$ intervals. The results are correlated with the vapor pressure. and showed with the miscibility as visualization for the individual text components.