• Tribology and Lubricants
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• 제15권3호
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• pp.233-239
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• 1999

Generally quantity of supply oil for piston ring lubrication in an internal combustion engine may be insufficient to fill the entire volume formed in the clearance between piston ring and cylinder liner. Thus oil starvation condition should be considered for the analysis of piston ring lubrication. In order to reasonably estimate amount of oil left on the cylinder liner, adequate boundary condition should be adapted for the analysis of ring pack lubrication. In this analysis of ring pack lubrication of an internal combustion engine, oil starvation and open-end boundary conditions are considered at inlet and outlet of piston rings. It is revealed that piston rings are operated under oil starvation in most operating cycle and the result with these conditions are quite different from that with fully-flooded assumption.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 추계학술발표회
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• pp.479-482
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• 2003

In this study, the solubilization of dense nonaqueous phase liquid (DNAPL) using oil-based emulsion was investigated for aquifer remediation. The micro-sized oil emulsion has large surface areas and buoyancy force, therefore it can be effective in treating DNAPL pool of the aquifer without downward migration of DNAPLs. The emulsion was prepared using silicone oil and mechanical homogenization. And the prepared emulsion had micro-sized similar distribution: 99 % in number and 80 % in volume were less than 10${\mu}{\textrm}{m}$. As target pollutants, trichloroethylene and 1, 2 dichlorobenzene were selected. All of used DNAPLs were solubilized successfully in oil-based emulsion. Even at low oil percentage, emulsion showed good solubility against pollutants. Therefore, the remediation using oil-based emulsion was considered as an effective alternative in dealing with DNAPLs of the aquifer.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.31-32
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• 2007

Oil-based nanofluids are prepared by dispersing spherical and fiber-shaped $Al_2O_3$ and AlN nanoparticles in transformer oil. Two hydrophobic surface modification processes are compared in this investigation. It is obvious that the combination of nanoparticle, surfactant and surface modification process is very important for the dispersity of nanofluids. For ($Al_2O_3$+AIN) particles with 1% volume fraction, the enhancement of thermal conductivity and convective heat transfer coefficient is nearly 11% and 30%, respectively, compared to pure transformer oil. The cooling effect of ($Al_2O_3$+AlN)-oil nanofluids on the heating element and oil itself is confirmed by a natural convection test using a prototype transformer.

• Applied Biological Chemistry
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• 제48권3호
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• pp.217-221
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• 2005

쇼트닝을 4% 첨가한 식빵과 올리브유를 0, 4, 6% 첨가한 식빵의 품질특성을 조사하기 위하여 수분함량, 굽기 손실, 비용적, 경도 및 탄력성 등을 측정하였다. 제품의 수분함량은 쇼트닝을 4% 첨가한 식빵이 $38.68{\pm}0.41%$, 올리브유를 4%와 6% 첨가한 식빵이 39.8% 내외로 유사한 값을 나타냈고, 굽기 손실은 쇼트닝 및 올리브유를 첨가한 식빵에서 차이를 나타내지 않았으나 유지를 첨가하지 않은 식빵은 낮은 굽기 손실을 나타냈다. 비용적은 쇼트닝을 4% 첨가한 식빵이 올리브유를 4% 첨가한 식빵보다 약간 높은 값을 나타냈고, 올리브유를 6% 첨가한 식빵은 3.90 ml/g로 유지를 첨가한 실험군 중 가장 낮은 값을 나타냈다. 경도와 탄력성은 쇼트닝을 4% 첨가한 식빵과 올리브유를 4%와 6% 첨가한 식빵에서 유의적인 차이가 없었고, 올리브유를 첨가하지 않은 식빵의 경도 값이 가장 커 조직이 단단한 것으로 나타났다.

• 한국항해항만학회지
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• 제27권2호
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• pp.239-246
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• 2003

해양에 기름이 유출되면 방제작업의 초기단계에서 기름의 이동 및 확산을 차단하기 위하여 오일 붐을 사용하는 것이 일반적이다. 그러나 오일 붐은 유속, 기름의 밀도와 점성, 수심, 기름의 양, 그리고 붐 흘수의 길이 등과 같은 여러 인자들에 의해 그 포획능력이 영향을 받는다. 본 연구에서는 이들 누유인자가 오일 붐의 포획과정에 어떠한 영향을 미치는지를 체계적으로 파악하기 위하여 컴퓨터 모델링을 수행하였다. 모델링을 위하여 CFD(computational fluid dynamics) 프로그램 중에서 가장 널리 알려진 Fluent를 이용하였으며 기존의 실험자료와 비교함으로써 모델링 결과를 검증하였다. 본 연구의 결과는 방제작업 책임자와 오일 붐 설계자에게 유용한 참고자료가 될 것으로 기대된다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2003년도 춘계공동학술대회논문집
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• pp.171-178
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• 2003

해양에 기름이 유출되면 방제작업의 초기단계에서 기름의 이동 및 확산을 차단하기 위하여 오일 붐을 사용하는 것이 일반적이다. 그러나 오일 붐은 유속, 기름의 밀도와 점성, 수심, 기름의 양, 그리고 붐 홀수의 길이 등과 같은 여러 인자들에 의해 그 포획능력이 영향을 받는다. 본 연구에서는 이들 누유인자가 오일 붐의 포획과정에서 어떠한 영향을 미치는지를 체계적으로 파악하기 위하여 컴퓨터 모델링을 수행하였다. 모델링을 위하여 CFD(computational fluid dynamics) 프로그램 중에서 가장 널리 알려진 Fluent를 이용하였으며 기존의 실험자료와 비교함으로써 모델링 결과를 검증하였다. 본 연구의 결과는 방제작업 책임자와 오일 붐 설계자에게 유용한 참고자료가 될 것으로 기대된다.

• 수산경영론집
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• 제40권1호
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• pp.153-172
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• 2009

Developing foreign fishing ground executed in various uncertainty such as fishing price, oil price, exchange rate. But traditional economic evaluation method, CVP(Cost-Volume-Profit) analysis doesn't consider uncertainty of foreign fishing ground. So we need new approach about economic evaluation that can take into account uncertainty. This study focus on the economic evaluation about experimental survey of tuna fishing grounds in the north pacific ocean by sensitive analysis and simulation. The results of the economic evaluation can be summarized as follows. First, when we take it for granted that the other uncertainty factors except for each fishing price, oil price, and exchange rate are constant. CVP gross sales has positive relation to the increasing rate of oil price, exchange rate(W/$) and negative relation to the increasing rate of fishing price and exchange rate(W/${\yen}$). Second, when we are supposing that fishing price, oil price, and exchange rate are followed. the probability of less than CVP gross sales is A ship(48.87%), B ship(49.64%), C ship(50.55%). Consequently, the economic evaluation by sensitive analysis and simulation is more useful tool than CVP(Cost-Volume-Profit) analysis under uncertainty.

• 한국가시화정보학회지
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• 제9권2호
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• pp.54-60
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• 2011

This paper is a basic study on volatile organic compounds(VOC) recovery system in a crude oil carrier. VOC is easily evaporated in cargo tankers during loading and transportation of crude oil, causes serious environmental contamination and a huge economic loss. An ejector system is designed to mix VOC gas into crude oil flow to reduce VOC concentration. Detail two-phase flow inside the ejector is simulated using a commercial CFD code. To verify the numerical prediction, a scale-down experiment is conducted. Instead of crude oil and VOC, water and air are used as the working fluids. Flow characteristics and main parameters are obtained by two-phase flow visualization and PIV measurements. Air volume flow rate induced by the ejector is compared with respect to the volume flow rate of water using experimental and numerical results. Overall performance of the two-phase ejector predicted by the CFD simulation agrees well with that of the experiment.

• Tribology and Lubricants
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• 제35권4호
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• pp.244-266
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• 2019

The purpose of this study is to estimate the wear volumes of engine journal bearings operating at variable angular velocity of a shaft in the beginning of firing start-up cycle. To do this, first we find the potential region of wear scar on engine journal bearings where the applied bearing load and crank shaft velocity are variable. The potential wear regions are discovered by finding minimum oil film thickness at every crank angle existing below most oil film thickness scaring wear (MOFTSW) obtained based on the concept of the centerline average surface roughness. Then we calculate the wear volume from the wear depth and two wear angles decided by the magnitude of each film thickness lower than MOFTSW at every crank angle. The results show that the expected wear region is located at a few bearing angles after and/or behind the upper center of a big-end bearing and the lower center of a main bearing. And the real wear region is similar to the estimated wear region. Further we find that the wear scar on an engine journal bearing may occur at re-starting time after switch-off of a start motor especially under the condition of high oil temperature.

• 한국해양환경ㆍ에너지학회지
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• 제1권2호
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• pp.40-51
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• 1998

유벽에 의하여 가두어진 오일의 조류중 거동을 회류수조에서 2차원적인 실험설비를 이용하여 살펴보았다. 유벽을 적정 깊이의 수직판으로 대치하고 레이저 광원을 이용하여 오일과 물과의 경계면 변형을 2 종류의 오일 (콩기름과 경유)에 대하여 관찰하였다. 적용된 조건으로 조류의 속도는 10 cm/s - 35 cm/s, 유벽의 깊이는 4 cm 와 8 cm, 그리고 유량은 2 liter - 8 liter 의 변화를 주었다. 다양한 경계면의 거동과 조건에 따른 누유의 손실 방식을 차원해석을 통하여 정리하고 유적누유와 연속누유의 발생 메카니즘을 설명하였다.