• Journal of Energy Engineering
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• v.24 no.2
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• pp.1-8
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• 2015

Wax deposition hinders oil flow assurance. Huge amount of money and time were required for mitigation of wax deposition in the oil field. For prediction and mitigation of wax deposition problem, Wax Appearance Temperature(WAT), which is the temperature at which the first wax crystals start to form, needs to be measured in advance. There is a standard method which is optical way to measure the WAT of transparent oil. However, standard method cannot be applied to opaque oil which is common produced oil in the field. In this study, WAT of three transparent oil samples were measured using heat flux variation analysis, viscosity variation analysis and density variation analysis, and compared with WAT measured by standard method. As a result, WAT measured by density variation analysis is the more reliable than heat flux variation analysis and viscosity variation analysis. WAT of two opaque oils were measured using density variation analysis.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.6-10
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• 2012

The main objective of this work was studying the influence of paraffin oil(PO) on the adhesion properties at low temperature in styrene-butadiene-styrene(SBS) copolymer and crumb rubber(CR) modified asphalt. The temperature susceptibility of SBS/CR asphalt and PO/SBS/CR/asphalt blends were measured by penetration and softening point. Adhesion properties at low temperature and dispersion of modifiers in PO/SBS/CR/asphalt blends were evaluated by universal test machine and florescence microscopy, respectively. The adhesion properties of PO/SBS/CR/asphalt blends at low temperature increased in the proportion of SBS contents with both 5 and 10 wt % of paraffin oil. Results showed that the maximum tensile adhesion strength and toughness energy at $-20^{\circ}C$ were obtained when PO and SBS contents were 10 wt % and 6 wt %, respectively. The addition of PO is effective for enhancing the flexibility of SBS/CR/asphalt blends and leads to the increase of toughness at low temperature.

• KDI Journal of Economic Policy
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• v.9 no.4
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• pp.25-58
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• 1987

본(本) 연구(硏究)는 해외여건 변화에 따른 우리나라 국제수지조정과정(國際收支調整過程)의 특징을 밝히며 아울러 이미 발표된 분기모형(分期模型) 추정기간(推定期間)을 1985년 제4분기까지 연장해 재추정한 결과를 보고하고 이를 이용해 해외여건 변화의 효과를 분석하고자 함에 그 목적이 있다. 국제수지(國際收支)의 변동(變動)을 요인별로 분화(分化)하여 보면 제1,2차 오일 쇼크 초기의 경상수지 악화는 유가급등(油價急騰)에 의한 교역조건 악화에 그 주인(主因)이 있다. 이후 경상수지 적자는 서로 다른 과정을 밟아 줄어들게 되는데 1976~77년의 경우 수출촉진(輸出促進)으로, 1981~82년의 경우 총수요조정(總需要調整)으로 국제수지 개선을 도모하였다. 이와 같이 양기간중 상이한 방법으로 적응한 것은 양기간중 해외여건이 서로 달랐기 때문이며 이 점에서 우리나라 국제수지의 조정도 여타 수출지향적(輸出指向的) 성장국(成長國)과 유사한 과정을 밟았다. 분기계량모형(分期計量模型)을 이용하면 제2차 오일 쇼크 기간에는 제1차 오일 쇼크 기간에 비해 유가(油價)가 상대적으로 덜 상승하였으나 해외수요(海外需要) 부진(不振), 달러강세(强勢) 및 고금리(高金利)로 해외여건은 전반적으로 우리 경제에 보다 불리하게 작용하였다. 1986년중 경상수지 흑자는 대부분 해외여건의 호전으로 설명되고 있다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.9
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• pp.967-972
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• 2009

To investigate the vibration characteristics of compact disc player(CDP) due to excited vibration and disturbances, it is necessary to consider the transmissibility of the CDP. The disturbances as well as the temperature in the vehicle are the one of the important factors when CDP is designed. In this study, the effect on the temperature of the oil damper, which is applied to anti-vibration system of the CDP, was investigated. When the temperature was changed from $-30^{\circ}C$ to $90^{\circ}C$ and the properties of the oil damper (hardness of rubber, viscosity of oil) were changed, the transmissibility was measured. When the damper rubber has the large hardness, the difference of the transmissibility and natural frequency due to temperature showed the remarkable change as compared with the those of damper viscosity.

• Journal of Energy Engineering
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• v.22 no.2
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• pp.237-244
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• 2013

The engine oil is used for lubrication of various internal combustion engines. Recently, the vehicle and engine oil manufacture usually guarantee for oil change over 15000~20000 km mileage, but the most of driver usually change engine oil every 5000 km driving in korea. It can cause to raise environmental contamination by used engine oil and increase the cost of driving by frequently oil change. In this study, we investigate the various physical properties such as flash point, pour point, kinematic viscosity, cold cranking simulator characteristics, total acid number, four-ball test and concentration of metal component for fresh engine oil and used engine oil after real vehicle driving (5000 km, 10000 km). The result showed that the total acid number, wear scar diameter by four-ball test, Fe and Cu had increased than fresh engine oil, but 2 kind of used oil (5000 km and 10000km) had similar physical values and concentration of metal component.

• Communications of the Korean Mathematical Society
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• v.12 no.4
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• pp.1015-1021
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• 1997

타원형 미분작용소의 이론을 이용하여 옹골 다양체에서 정의된 벡터장의 특이점에 관한 푸앵카레-호프의 이론과 평다발의 오일러-푸앵카레 특성수를 연관시키는 법을 살펴보았다.

• Journal of the Korean Applied Science and Technology
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• v.32 no.1
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• pp.148-156
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• 2015

In this study the differences in the sample size and sample input changes as characteristics of bio-oil oak(Quercus variabilis), the oak 0.5~2.0 mm of the oak weighing 300~900g was processed into bio-oil via fast pyrolysis for 1.64 seconds. In this study, the physico-chemical properties of biooil using oak were investigated. Fast pyrolysis was adopted to increase the bio-oil yield from raw material. Although the differences in sample size and sample input changes in the yield of pyrolysis products were not significantly noticeable, increases in the yield of bio-oil accounted for approximately 60.3 to 62.1%, in the order of non-condensed gas, and biochar. When the primary bio-oil obtained by the condensation of the cooling tube and the seconary bio-oil obtained from the electric dust collector were measured separately, the yield of primary bio-oil was twice as higher than that of the secondary bio-oil. However, HHV (Higher Heating Value) of the secondary bio-oil was approximately twice as higher than that of the primary bio-oil by up to 5,602 kcal/kg. The water content of the primary bio-oil was more than 20% of the moisture content of the secondary bio-oil, which was 10% or less. In addition, the result of the elemental analysis regarding the secondary bio-oil, its primary carbon content was higher than that of the primary bio-oil, and since the oxygen content is low, the water content as well as elemental composition are believed to have an effect on the calorific value. The higher the storage temperature or the longer the storage period, the degree of the viscosity of the secondary bio-oil was higher than that of the primary bio-oil. This can be the attributed to the chemical bond between the polymeric bio-oil that forms during the storage period.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.579-584
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• 2017

The damper oil seal of a high-speed railway vehicle is made from nitrile butadiene rubber (NBR) in order to prevent lubricant from leaking into the damper and to stop harmful contaminants from entering the external environment while in service. Oil leakage through the seal primarily occurs from fatigue failure of the damper. Cumulative damage of the seal occurs due to the contact force between the rod and the rubber during movement due to track irregularities and cants, among other factors. Thus, the design of the oil seal should minimize the maximum principal strain at weak points. In this study, the optimal cross section of the damper oil seal was found using the multi-island genetic algorithm method to improve the durability of the damper. The optimal shape of the oil seal was derived using process automation and design optimization software. Nonlinear material properties for finite element analysis (FEA) of the rubber were determined by Marlow's model. The nonlinear FEA confirmed that the maximum principal strain at the oil leakage point was decreased 24% between the initial design and the optimum design.

• Review of KIISC
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• v.21 no.5
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• pp.55-64
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• 2011

제어 시스템은 수도, 오일 등 국가기반시설을 감시 및 제어하는 시스템이다. 최근 이러한 제어 시스템을 공격 목적으로 하는 사이버 공격이 발생하고 있어 제어 시스템에 대한 보안 필요성이 대두되고 있다. 이러한 제어 시스템은 일반적인 IT 시스템과는 달리 상이한 구조적 특성을 갖고 있어 제어 시스템의 특성에 맞는 보안정책을 마련해야 한다. 이를 위해 각 국가에서는 제어 시스템의 보안정책을 재정립하고 있으며 연구기관을 설립하고 프로젝트를 진행하는 등 보안 취약점을 해결하기 위한 노력을 하고 있다. 따라서 본 고에서는 국내 외 제어 시스템에 대한 보안정책 동향 및 보안 취약점을 분석하고자 한다.

• Journal of Energy Engineering
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• v.8 no.1
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• pp.189-201
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• 1999

범용 열가소성 플라스틱(polyethylene(PE), polypropylene(PP), polystyrene(PS), polyethylene-terephthalate(PET), acrylonitrile-butandiene-styrene(ABS))과 폐윤활유의 동시처리 열분해반응 실험을 수행하였다. 반응실험은 40$m\ell$ 용량의 회분식 미분반응기(microreactor)를 이용한 실험과 1리터 용량의 autoclave를 이용한 실험의 두 가지로 구분하여 행하였다. 전자의 경우는 통계적 실험적계획법(statistical experimental design)의 하나인 회전계획실험(rotatable design experiments)으로서 오각형 실험계획(pentagonal experimental design)에 의거한 반응변수 실험을 수행한 후 반응표면(response surface)을 회기분석법에 의하여 분석함으로써 최대의 오일 수율을 얻을 수 있는 최적 반응조건을 추적, 결정하였다. Autoclave 반응실험의 기본적인 목적은 실제 연속공정에 있어서 열분해 반응기 거동을 모사하기 위한 전초단계로서 충분한 시료의 확보를 통하여 이 때 생성된 연로유의 체계적인 분석(비등점분포특성, 진공증류, 기체분석, 원소분석, 발열량, 비중 등)을 행함으로써 연료유 수율 및 품질을 모사하고자 하였다. 미분반응기 실험에 있어서 주 범용열가소성수지인 PE, PP 그리고 PS는 각각의 최적반응조건하에서 거의 100%에 가깝게 오일로 전환되었지만 응축수지인 PET와 그래프트공중합수지인 ABS의 오일수율은 각기 78% 및 90%로서 상대적으로 낮게 나타났다. Autoclave를 이용한 실험의 경우 혼합플라스틱을 폐유에 대하여 40wt% 혼합하여 열분해하였을 때, 80wt% 오일, 15wt% 코우크, 그리고 나머지 5wt%는 탄화수소기체(C1-C6)로 전환되었다. 진공증류(252$^{\circ}C$,2 torr) 결과, 기/액-분리도는 3으로서 이는 생성오일의 75wt%가 경질연료유(가솔린, 등유, 경유)로 회수 가능하였다.