• Journal of Biosystems Engineering
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• 제38권3호
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• pp.208-214
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• 2013

Purpose: Performances of a tractor diesel engine fueled by three different animal fats biodiesels were evaluated comparing with light oil tractor in terms of power, fuel consumption rate, exhaust gases, particulate matter amount and field work capacity. Methods: Animal fats based on pig biodiesel were manufactured manually and tested for its engine performance in the tractor diesel engine and fuel adoptability in the field works. Four different fuels, three different content of biodiesel (BD20, BD50, BD100) and light oil, were prepared and tested in the four strokes diesel engine. Power output, fuel consumption rate and exhaust gases of the four fuels in the diesel engine were compared and discussed. Results: Power output of light oil engine was the greatest showing 5.3% difference between light oil and BD100, but 0.37% better power than BD20 engine power. Less exhaust gases of $CO_2$, CO, $NO_X$ and THC were produced from animal fats biodiesel than light oil, which confirmed that biodiesel is environmental friendly fuel. For fuel adoptability in the tractor, biodiesel engine tractor showed its fuel competitiveness comparing with light oil for tractor works in the faddy field. Conclusions: With four different fuel types of animal-fats biodiesel, performances of a four cylinder diesel engine for tractor were evaluated in terms of power, exhaust gases, particulate matters (PM) and field work capacity. No significant differences observed in the engine performances including power output and exhaust gases emission rate. No significant power difference observed between the various fuels including light oil on the engine running, however, amounts of noxious exhaust gases including $CO_2$ and $NO_X$ decreased as biodiesel content increased in the fuels. Field performances of animal-fats biodiesel tractor were investigated by conducting plowing and rotary operation in the field. Tilling and rotary performance of light oil tractor and BD20 tractor in the field were compared, in which about 10% travelling speed difference on both operations were monitored that showed light oil tractor was superior to BD20 tractor by 10%. Animal-fats can be an alternative fuel source replacing light oil for agricultural machinery and an environmental friendly fuel to nature.

• 해양환경안전학회지
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• 제5권1호
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• pp.9-18
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• 1999

To predict the oil spill dispersion phenomena in the ocean, the oil spill response model, which can be used for strategic purpose on the oil spill site, based on Lagrangian particle-tracking method was formulated and applied to the neighboring area with Pusan port where the oil spill incident occurred when the tanker ship No.1 Youil struck on a small rock near the Namhyungjeto on September 21, 1995. The real-time tidal currents to be required as input data of the oil spill model were obtained by the two-dimensional hydrodynamic model and the tide prediction model. Evaluation of tidal currents using observation data was successful. For wind data, other input data of oil spill model, observed data on the spot were used. To verify the oil spill model, the oil spill modelling results were compared with the field data obtained from the spill site. Compared the modelling results with the observation data, there exist some discrepancies but the general pattern of modelling results was similar to that of field observation. The modelling results on 7 days after spill occurred showed that the 40% of spilled oil is in floating, 36% in evaporated, 23% at shore, and 1% in out of boundary, respectively. According to the evaluation of weighting curves of effective components to the dispersion of oil, the winds make a 37% of contribution to the dispersion of oil, turbulent diffusion 39.5%, and tidal currents 23.5%, respectively. Provided the more accurate wind data are supported, more favorable results might be obtained.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1997년도 제26회 추계학술대회
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• pp.161-166
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• 1997

Application of hot roiling oil lubrication technology was broadened to the field of RM stands of Hot Rolling Mill at Pohang works. The primary object was to improve the quality of the strip sttrface and the rolls by oil lubrication in hot rolling process. Prior to the actual field application preliminary test was conducted to evaluate the effect of hot rolling oil lubrication at RM stands. From the test, it has been found that the use of oil lubrication tends to prevent the progression of the heat cracks and thereby increases the quality of the strip surface and the wear life of the rolls. New hot rolling oil lubrication system was applied to the RM stands VSB, R1, R2, R3, R4 and edger rolls. With the introduction of a rolling lubricant, the quality of the strip surface and rolls was improved and overall roll dressing has decreased. Also there has been a improvement of productivity from the long roll life.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.772-776
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• 2001

The flow structures of turbulent shear layer behind oil fences with different tip configurations were investigated experimentally using flow visualization and PIV velocity field measurement. An oil fence was installed in a circulating water channel and the flow structure around the fence tip was mainly analyzed in this experiment. The four tip configurations tested in this experiment are knife edge; semi-circle edge, circular edge and rectangular edge. The 300 instantaneous velocity fields were measured using the single-frame PIV system and they were ensemble averaged to give the mean velocity field and spatial distribution of turbulent statistics. Free stream velocity was fixed at 10ms/sec and the corresponding Reynolds number based on the fence height was Re=4000. As a result, for the oil fence with rectangular edge, the streamwise velocity component was decreased. On the other hand it was increased for the oil fence with circular edge. For all four fences tested in this study, general flow pattern of the lower shear layer is analogous but the upper layer shows difference depending on the tip configurations. The oil fence with circular edge has more diffusive upper shear layer than that of the others. The shear layer of the oil fence with rectangular edge has relatively thin thickness. The oil fence with circular edge was found to be proper shape for tandem fence.

• Environmental Analysis Health and Toxicology
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• 제21권2호
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• pp.103-113
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• 2006

This study examined effects of crude oil on the phase II drug-metabolizing enzymes UDP-glucuronosyl transferase (UDPGT) and glutathione S-transferase (GST) in mussel Mytilus edulis and rockfish Sebastes schlegeli, a representative bivalve and a culture fish, respectively. This work also intended indirectly to evaluate the post impact recovery from the massive oil tanker spillage accidents occurred during the summer of 1995 in the sea area off Yosu City, Chonnam. For these, enzyme activities of UDPGT and GST were examined in the fish and mussel following laboratory exposure to fresh crude oil, weathered oil, field-obtained oil residues, or in the field biota samples. Decreased GST activity was observed in rock fish following exposure to oil-soluble fraction (OSF) of fresh oil. A similar diminished GST activity was also observed after OSF of artificially weathered oil. OSF of field oil residues retrieved from the spillage area approximately 1 year later also exerted a slight inhibition of GST to rockfish. There was neither a change in UDPGT in rockfish, nor were there changes in mussel in both enzymes to any oil fractions. We could not observe any difference in the two enzymes either in rockfish or mussel sampled from the field during $1.5{\sim}2.0$ years post spillage, indicating that their enzyme systems might had been recovered by the sampling time. In conclusion, it seems that the inhibition of GST activity in rockfish is a biomarker response to crude oil exposure. The results, however, must be interpreted with care, as the inhibition nay reflect various factors such as oil concentration, duration and water temperature.

• 한국전기전자재료학회논문지
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• 제36권4호
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• pp.408-412
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• 2023

In this paper, in order to analyze high electrical insulation and cooling performance using mineral oil, the liquid insulating oil was changed in electrode shape and distance between electrodes to compare and analyze electrical characteristics according to equal electric field, quasi-equivalent electric field, and unequal electric field. As a result, the breakdown voltages were 36,875 V and 36,875 V in the form of sphere-sphere and plate-plate electrodes with equal electric fields. The breakdown voltage was 31,475 V in the sphere-plate electrode type, which is a quasi-equilibrium field, and the breakdown voltage was 28,592 V, 27,050 V, and 22,750 V in the needle-needle, sphere-needle, and needle-plate electrode types, which are unequal fields. Through this, it is possible to know the difference in breakdown voltage according to the type of electric field. The more equal the field, the higher the breakdown voltage, and the more unequal field, the lower the breakdown voltage. The difference in insulation breakdown voltage could be seen depending on the type of electric field, the insulation breakdown voltage was higher for the more equal electric field, and the insulation breakdown voltage was lower for the more unequal electric field. Also, it was confirmed that the closer the distance between the electrodes, the higher the insulation breakdown voltage, the higher the insulation breakdown current, and the insulation breakdown voltage and the insulation breakdown current were proportional.

• 해양환경안전학회지
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• 제3권1호
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• pp.73-83
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• 1997

To predict the oil-spill dispersion in marine waters, the oil-spill dispersion model based on Lagrangian particle-tracking method was developed and applied to Kwangyang and Jinju Bay. The tidal current movements to be required as input data of the oil-spill dispersion model were obtained by a two-dimensional numerical tidal model. Evaluation of tidal current movements using mean tide was successful. Modelling results were compared with the field data obtained at spill site. There were some descrepancies between modeling results and field data. However, the general pattern of modelling results was similar to that of field data. Provided the real-time tidal currents and more accurate wind data are supported, more favorable results can be obtained.

• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.865-873
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• 2017

Converter transformer is the key equipment of high voltage direct current transmission system. The solid suspending particles originating from the process of installation and operation of converter transformer have significant influence on the insulation performance of transformer oil, especially in presence of DC component in applied voltage. Under high electric field, the particles easily lead to partial discharge and breakdown of insulating oil. This paper investigated copper particle effect on the breakdown voltage of transformer oil at combined AC and DC voltage. A simulation model with single copper particle was established to interpret the particle effect on the breakdown strength of insulating oil. The experimental and simulation results showed that the particles distort the electric field. The breakdown voltage of insulating oil contaminated with copper particle decreases with the increase of particle number, and the breakdown voltage and the logarithm of particle number approximately satisfy the linear relationship. With the increase of the DC component in applied voltage, the breakdown voltage of contaminated insulating oil decreases. The simulation results show that the particle collides with the electrode more frequently with more DC component contained in the applied voltage, which will trigger more discharge and decrease the breakdown voltage of insulating oil.

• Korean Chemical Engineering Research
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• 제45권6호
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• pp.638-647
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• 2007

본 연구에서는 회수증진기법 중 하나인 $CO_2$ 공법을 생산유전에 적용할 경우, 적용성 여부를 간단하고 정량적으로 평가할 수 있도록 하기 위한 평가차트를 개발하였다. 이 평가차트는 소스의 이용성, $CO_2$-오일의 혼합도, 저류층 및 오일 특성의 적정성, 주입기법의 평가항목으로 구성되어 있다. 저류층 및 오일의 특성에서 오일 비중, 오일 점성도, 오일 포화도, 저류층 온도 및 투과도의 기본평가항목에 대해서는 점수로 평가되며, $CO_2$ 순도, 저류층 두께 및 경사도 등의 추가평가항목에 대해서는 상 중 하로 구분하여 정량적으로 평가된다. 또한 미서블공법의 주입기법 평가에서는 지층경사, 수직투과성 및 저류층 두께 등에 따라 연속주입공법과 WAG($CO_2$) 공법의 여부가 정성적으로 평가된다. 이와 같이 구성된 평가차트에 대해 $CO_2$ 공법이 성공적으로 수행된 51개 유전의 적용사례를 분석하여 이를 토대로 $CO_2$ 공법이 가능한 추천점수를 설정하였다. 본 연구에서 개발한 평가차트를 국내 기업이 참여중인 스코틀랜드의 캡틴 생산유전과 베네수엘라의 오나도 생산유전에 적용하여 $CO_2$ 공법의 적용 가능성 여부를 평가하였다. 여기서 캡틴 유전은 저류층의 공극률과 투과도가 매우 양호하나, $C_{21+}$ 이상의 무거운 탄화수소 함유량이 54%를 넘는 중질유이다. 따라서 이러한 중질오일은 $CO_2$와 비미서블공법으로 진행되므로 비미서블공법 기준하의 기본평가항목에 대해서만 평가한 결과 비미서블 $CO_2$ 공법이 적정한 것으로 평가되었다. 한편, 베네수엘라의 오나도 유전에 대해서는 최소 미서블압력이 저류층 압력보다 낮게 산출되어 미서블 $CO_2$ 공법이 적용 가능할 것으로 평가되었다.

• 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.