• Tribology and Lubricants
• /
• 제10권1호
• /
• pp.14-26
• /
• 1994

The minimum oil film thickness(MOFT) in the connecting-rod bearing of a 1.5 liter, L-4, gasoline engine is measured up to 5500 rpm and calculated to study the dynamically loaded engine bearing. Short bearing approximation and Mobility method are used for theoretical analysis of oil film characteristics. And cylinder pressure, crank-pin surface temperature and bearing temperature are measured as the input data of theoretical analysis. The MOFT are measured by the total capacitance method(TCM). To improve the reliability of the test results, a reasonable determination method of bearing clearance is introduced and used, and the effects of cavitation and aeration on the test results are neglected. The crankshaft is grounded by means of a slip ring. A scissor type linkage system was developed to measure the MOFT and bearing temperature. The effects of engine speed, load and oil viscosity on the measured and calculated minimum oil film thicknesses are investigated at 1500 to 5500 rpm. From the comparison between the measured and calculated MOFT, it is found that a qualitative similarity exists between them, but in all cases, the measured MOFT are smaller than those calculated.

• Journal of Electrical Engineering and Technology
• /
• 제9권3호
• /
• pp.957-963
• /
• 2014

Converter transformers play important roles in high-voltage direct current transmission systems. This paper presents experimental and analysis results of the combined electrical and thermal aging of oil-impregnated paper at pulsating DC voltages. Breakdown voltages and time-to-breakdown of oil-paper specimens were measured by using short-time and constant-stress tests. The breakdown characteristics of combined electrical and thermal aging on insulation system were discussed. According to the relationship between failure time and aging temperature, the two-parameter Weibull model was improved. On the basis of the competing risk algorithm and the improved Weibull model, the two factors failure model was calculated. And the influence of temperature in the insulation system has been analyzed. This model performs better than the two-parameter Weibull model when both time and temperature are considered as variables in estimating the lifetime of oil-paper insulation.

• 전기학회논문지
• /
• 제66권12호
• /
• pp.1745-1750
• /
• 2017

Starting from the distribution transformer, the insulation oil for the oil immersed power transformer is being used to convert the vegetable oil from the existing mineral oil. Vegetable oil is better in temperature characteristics and insulation performance, is not toxic, and has better biodegradable characteristic than that of mineral oil. In order to investigate the corona inception voltage and dieclectic charateristics of the two insulating oils, three oil immersed transformers using mineral oil and vegetable oil were made and thermal cyclic aged. In this paper, the changes in the corona discharge inception voltage, chemical and electrical properties of the two sampled insulating oils from the transformers had been studied.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 1999년도 제29회 춘계학술대회
• /
• pp.359-365
• /
• 1999

We have evaluated the performance and some physical properties of 25 automotive engine oils (21 domestic and 5 imported products) which are purchased on the market to verify the API(American Petroleum Institute) or ILSAC(International Lubricant Standardization and Approval Committee) certification marks attached on the products and to determine the necessity of the quality control of the engine oils on the market. 12 test items are chosen according to API engine oil specification, which are flash point, pour point, cold cranking simulator apparent viscosity, pumping viscosity, gelation index, HTHS(High Temperature High Shear viscosity), foam, high temperature foam, filterability, volatility, high temperature deposit(TEOST), phosphorus content. We have found one product which did not meet the API specification on gelation index, one on HTHS, four on foam, and one on volatility, which implies that the quality control system is in need to check the fidelity of the certification marks attached on the engine oils being marketed. In addition, this works raises the necessity of the upgrade of the present Korean engine oil specification.

• 한국응용과학기술학회지
• /
• 제23권4호
• /
• pp.307-318
• /
• 2006

The pyrolysis of high density polyethylene(HDPE) and low density polyethylene(LDPE) was carried out at temperature between 425 and $500^{\circ}C$ from 35 to 80 minutes. The liquid products formed during pyrolysis were classified into gasoline, kerosene, gas oil and wax according to the petroleum product quality standard of Korea Petroleum Quality Inspection Institute. The conversion and yield of liquid products for HDPE pyrolysis increased continuously according to pyrolysis temperature and pyrolysis time. The influence of pyrolysis temperature was more severe than pyrolysis time for the conversion of HDPE. For example, the liquid products of HDPE pyrolysis at $450^{\circ}C$ for 65 minutes were ca. 30wt.% gas oil, 15wt.% wax, 14wt.% kerosene and 11wt.% gasoline. The increase of pyrolysis temperature up to $500^{\circ}C$ showed the increase of wax product and the decrease of kerosene. The conversion and yield of liquid products for LDPE pyrolysis continuously increased according to pyrolysis temperature and pyrolysis time, similar to HDPE pyrolysis. The liquid products of LDPE pyrolysis at $450^{\circ}C$ for 65 minutes were ca. 27wt.% gas oil, 18wt.% wax, 16wt.% kerosene and 13wt.% gasoline.

• Geomechanics and Engineering
• /
• 제19권6호
• /
• pp.523-532
• /
• 2019

Based on the formation characteristics, wellbore parameters and insulated tubing (IT) parameters of the Shengli oilfield, Shandong, China, a geomechanical model is built to predict the temperature distributions of the wellbore and formation. The effects of the IT heat conductivity coefficient (HCC), well depth and IT joint on the temperature distribution of the IT, completion casing, cement sheath, and formation are investigated. Results show the temperature of the formation around the wellbore has an exponentially decreasing relation with the distance to the wellbore. The temperature of the formation around the wellbore has an inverse relation with the IT HCC when the temperatures of the steam and the formation are given. The temperature of the casing outer wall is mainly determined by the steam temperature and IT HCC rather than by the initial formation temperature. The temperature of the casing at the IT joint is much larger than that of the other location. Due to the IT joint having a small size, the effects of the IT joint on the casing temperature distribution are limited to a small area only.

• 한국식품과학회지
• /
• 제23권1호
• /
• pp.76-80
• /
• 1991

미강유 정제 부산물로부터 오리자놀을 분리하기위해, dark oil과 dark oil의 증류잔류물인 pitch로부터 용매분리법 이용하여 오리자놀을 분리하였다. 분리과정 중 방해물질인 왁스분은 dark oil과 acetone을 1 : 1(w/v)로 혼합하여, $0^{\circ}C$에서 침전시켜 제거하였고, 여기에서 얻어진 dewaxed dark oil에 8 part의 hexane을 섞어 저온분리하여 오리자놀함량이 51.3%인 농축물을 얻었다. 이 농축물에 methanol 20 part를 가하고 재결성하여 98.3%의 오리자놀결정물을 얻었다. Dark oil로부터 pitch를 제조하는 적정조건은$180^{\circ}C$와 $0.2{\sim}0.4torr$의 진공상태에서 2%(w/w)의 steam을 가하는 증류조건이 오리자놀의 파괴를 최소화 하였다. 이로부터 얻어진 pitch의 오리자놀순도와 회수율은 27.3%와 82.3%였다. Pitch에 hexane을 가하고 저온분리하여 오리자놀순도가 75.4%인 오리자놀결정물을 얻었으며 이 농축물에 methanol을 가한 후 재결정하여 순도가 99%인 결정물을 얻었다. 이상과 같은 저온윤리법을 이용하였을 때 오리자놀의 회수율은 dark oil 9.5%, pitch 28.5%로 나타났다.

• 한국식품영양학회지
• /
• 제11권3호
• /
• pp.272-277
• /
• 1998

탈취온도를 상이하게 처리한 옥수수기름들로부터 정유성분을 추출하여 이의 favor 성분을 GC로 분리 정량하였다. Flavor성분으로는 8종의 aldehydes를 포함하여 총 16종이 검출되었으며, 주요 flavor성분은 propane, pentane, hexanal 등으로 이는 전체의 70~75%를 차지하였다. 탈취온도가 상승할수록 ethane 및 8종의 propane, pentane, hexane, octane, pentyl furna 함량은 뚜렷한 감소현상을 나타내었다. 한편, 총 flavor 성분함량은 245$^{\circ}C$ 처리군에서 가장 낮아 특이성을 나타내었으며, 탈취온도의 상승에 따라 aldehydes 함량이 비례적으로 증가하였는데, 이는 탈취과정 중 stripping steam, 진공도 등의 영향으로 인한 부분인 자동산화, 분해, 중합, 가수분해 등의 부반응에 기인하는 것으로 사료된다. 따라서, 이취물질의 극소화를 위하여는 지나친 고온탈취를 억제하는 것이 바람직하다는 결론을 얻었다.

• 센서학회지
• /
• 제25권5호
• /
• pp.344-348
• /
• 2016

We developed a 2-channel fiber-optic temperature sensor (FOTS) using a temperature sensing probe, a fiber-optic coupler, transmitting optical fiber, and an optical time domain reflectometer (OTDR). The temperature sensing probe is divided into a sensing probe and a reference probe for accurate thermometry. A sensing probe is composed of a silicon oil, a FC terminator, a brass pipe, and a singlemode optical fiber and the structure of a reference probe is identical with that of the sensing probe excluding a silicon oil. In this study, we measured the modified optical powers of the light signals reflected from the temperature sensing probe placed inside of the water with a thermal variation from 5 to $70^{\circ}C$. Although the optical power of the reference probe was constant regardless of the temperature change, the optical power of the sensing probe decreased linearly as the temperature increased. As experimental results, the FOTS using a subtraction method showed a small difference (i.e., hysteresis) in its response due to heating and cooling. The reversibility and reproducibility of the FOTS were also evaluated.

• 한국자원리싸이클링학회:학술대회논문집
• /
• 한국자원리싸이클링학회 2005년도 추계정기총회 및 제26회 학술발표대회 고분자리싸이클링기술 특별심포지엄
• /
• pp.47-58
• /
• 2005

온도변화에 따른 볏짚의 열분해 생성물의 분포와 생성물의 화학적 구성을 알아보기 위하여 볏짚의 열분해 실험을 진행하였다. 열분해 온도는 약 466, 504, $579^{\circ}C$사이에서 진행하였다. 유동화 가스로는 생성가스를 사용하였으며 유량은 30L/min을 사용하였다. 볏짚의 열분해 결과 기체, 액체, 고체 물질을 얻을 수 있었다. 기체물질은 GC(TCD, FID)를 이용하여 성분 조성을 분석하였다. 액체물질은 상등액과 tar로 분리하여 발열량, 원소분석, 수분, GC/MS를 통해 화학구성성분을 분석하였다. 고체물질은 원소분석, 발열량을 측정하였다. 액체물질의 화학특성 분석결과 연료뿐만 아니라 화학 원료물질로서의 사용가능성을 볼 수 있었다.