• 한국해양환경ㆍ에너지학회지
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• 제15권1호
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• pp.19-21
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• 2012

내연 기관의 엔진오일은 열화작용에 의해서 수명이 짧아지고 대기오염을 유발하게 된다. 엔진오일의 상태를 정확히 측정하여 새오일로 교환함으로 엔진의 수명 연장 및 환경오염을 줄일 수 있다. 정전용량 프로브는 엔진오일과 같은 유체의 유전율을 측정하는데 사용 할 수 있다. 본 논문은 엔진 오일의 열화 정도에 따라서 달라지는 유전율 특성을 분석하였다. 오일의 상태에 따라서 달라지는 프로브의 정전용량을 각각 LCR Meter로 측정하여 엔진오일의 유전율을 계산하였다. 또한, 프로브의 크기에 따른 정전용량의 변화를 측정하여 유전율 측정의 정확도를 제시한다. 오염된 오일 일수록 유전율이 증가하며, 유전율로 오일의 오염정도를 판단하는 것이 가능하다.

• 한국응용과학기술학회지
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• 제4권2호
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• pp.19-23
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• 1987

The addition of dipeptides and 1,2-bis (aminoacyl) hydrazine derivatives a level of 250 ppm to corn oil resulted in the retardation of the oxidaitive deterioration of the oil when it was stored in the oven at $70^{\circ}C$ during 5 days. Their antioxidant activities were investigated by UV absorbance of the corn oil at the wavelength of 234nm. 1,2-bis (aminoacyl) hydrazine derivatives showed higher antioxidant activity than normal dipeptides. Dipeptides containing phenyl ring with which is conjugable a-carbon radical showed antioxidant activity.

• 한국자동차공학회논문집
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• 제13권6호
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• pp.99-104
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• 2005

The CARB in USA has demanded OBD functions that detect any deterioration of performance of OTS as well as a simple defect of OTS which can affect emission to meet the reinforced emission regulation. In this paper, OTS plausibility monitoring functions to meet the demand from CARB are discussed. The output from OTS is used for the diagnostics of the torque converter clutch stuck and the gear ratio synchronous error. It is possible to diagnose the abnormality of OTS function by considering the oil temperature characteristics which changes according to the driving status of vehicles. In result, the OBD regulations of the CARB can be satisfied obligating car manufacturer to detect any problems in OTS functions which can affect emissions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.1912-1914
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• 2005

The electrical, chemical and mechanical characteristics in transformer insulations are changed due to thermal stress. It is known that characteristics of transformer insulations is deteriorated such as decrease of dielectric strength, deterioration of dielectric constant and tensile strength of paper as transformer oil and paper are aged by thermal stress. Furthermore, chemical characteristics of them are deteriorated as like increment of moisture contents and dissolved by-products in oil, etc. In this paper we have been investigated chemical characteristics of transformer by accelerated thermal aging. For this working we have made experimental test cell and aged at a temperature up to $140^{\circ}C$ for 500 hours. The oil-paper insulation samples have been measured at intervals of 100 hours. For analysis we used Karl-Fisher titration method and high performance liquid chromatography (HPLC).

• 동력기계공학회지
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• 제22권1호
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• pp.48-55
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• 2018

It has recently been reported that methanol fuel has been used in the product carrier with established duel fuel engine, which has been greatly reducing emissions of $CO_2$, NOx and SOx from the engine. However, to use methanol alone as fuel oil in a general diesel engine, design modification of cylinder head is needed because the ignition aid device or the duel fuel injection system is needed. On the other hand, only if the mixer is installed on the fuel oil supply line, diesel oil - methanol blending oil can be used as fuel oil for the diesel engine, but there is a problem of the phase separation when two fuels are mixed. In this study, diesel oil and methanol were blended compulsorily in preventing the phase separation with installing agitators and a fuel oil boost pump on fuel line of a test engine. Also, cylinder pressure and fuel consumption quantity were measured according to engine load and methanol blending ratio, and indicated mean effective pressure, heat release rate and combustion temperature obtained from the single zone combustion model were analyzed to investigate the effects of latent heat of vaporization of methanol on combustion stability and characteristics. As a result, the combustion stability and characteristics of 10% methanol blending oil are closest to the those of diesel oil, and it could be used as fuel oil in existing diesel engines without deterioration of engine performance and combustion characteristics.

• Journal of Advanced Marine Engineering and Technology
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• 제30권6호
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• pp.662-668
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• 2006

The effects of fuel injection nozzle hole on the NOx emission and fuel oil consumption of medium speed diesel engine HYUNDAI HiMSEN 6H21/32 engine are investigated by engine performance simulation. The results of performance simulation are verified by experimental results of NOx omission fuel oil consumption, cylinder pressure, and heat release rate according to the variation of the number of fuel injection nozzle hole and engine load. The performance simulations are also carried out to optimize the fuel injection nozzle of 6H21/32 engine in respect to the NOx emission and fuel oil consumption. The engine performance measurements are performed to verify the results of performance simulation and to investigate the effects of fuel injection nozzle on engine performance. The results of measurement indicate that significant NOx reduction can be achieved with minimum deterioration in fuel oil consumption by optimizing the geometry of fuel injection nozzle on 6H21/32 engine.

• 보존과학회지
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• 제37권5호
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• pp.426-439
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• 2021

유화 색맞춤에 사용되는 복원용 물감과 아크릴과슈에 대하여 물감별 특성을 파악하고 자외선 및 흡습건조 열화실험을 통하여 복원재료로서의 내구성을 확인하였다. 4개 제조사에서 제작된 총 20종의 물감을 사용하였으며 분석 결과 동일한 색명의 물감일지라도 제조사별 성분 및 발색 특성 차이가 존재했다. 이는 제조 시 체질, 착색 안료로 사용된 안료의 차이에서 기인한 것으로 판단된다. 열화 후 대부분의 시료에서 𝚫E^* 12.0 이상의 변색이 일어났으며, C사의 Viridian에서는 광택 변화도 관찰되었다. Lemon Yellow에서는 변색과 균열이 모두 관찰되었다. 균열은 복원용 물감인 B사의 것에서 가장 많이 발생했다. 이는 제조 시 사용된 수지의 영향인 것으로 추측되나 향후 정확한 원인 규명을 위해 변수를 통제하여 추가적인 연구가 진행되어야 할 것이다. 연구를 통해 색맞춤용 재료의 색 및 제조사에 따른 물리적 특성 차이가 확인되었으므로, 유화 보존처리자는 색맞춤 시 재료별 변색, 균열, 광택 변화와 같은 물리적 특성을 고려하여 복원재료의 선정 및 사용에 신중해야 할 것이다.

• 드라이브 ㆍ 컨트롤
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• 제19권1호
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• pp.69-75
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• 2022

This study aimed to develop solutions for the intermittent performance deterioration of self-propelled spinach harvesters through analysis model. The study was conducted in the following manner. First, changes in performance deterioration and surplus flow, which result from oil temperature changes, were analyzed by simulating actual sequential harvesting movements, which involve driving with actuators operated simultaneously, by analysis model developed in a previous study. Second, fundamental solutions for surplus flow problems were presented. Third, the solutions were applied to a virtual environment to present their practicality and quantitative effects. The two solutions based on the study results were as follows. First, a closed center-type directional control valve was applied to the hydraulic circuit. Second, an unloading system was set up through an on-off solenoid valve.

• 한국조명전기설비학회지:조명전기설비
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• 제10권5호
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• pp.94-100
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• 1996

자외- 가시선 흡수분광광도법을 적용하여 주상변압기 절연유의 판정기준을 제시하였다. 절연유가 열화하면 절연유의 전기적 특성치가 저하할 뿐만 아니라 흡광도값도 변하게 된다. tan$\delta$와 절연파괴전압과 같은 전기적 특성치를 흡광도값과 비교하여 흡광도값에 의한 절연유의 판정기분을 설정하였다. 흡광도값이 0.580 이하는 양호, 요주의는 0.580~0.900, 불량은 0.900이상이다. 자외-가시건 흡수분광광도법은 절연유의 열화분석에 적용할 수 있으며, 기존의 육안에 의한 절연유 검사 방법을 대체할 수 있을 것으로 기대된다. 그러나 분광광도법을 현장에 적용하려면 저렴하고 경량화된 휴대용 분광광도계의 개발이 필요하다.

• Journal of Biosystems Engineering
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• 제43권3호
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• pp.219-228
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• 2018

Purpose: This study evaluated the feasibility of a near-infrared spectroscopy technique for the rancidity prediction of soybean oil. Methods: A near-infrared spectroscopy technique was used to evaluate the rancidity of soybean oils which were artificially deteriorated. A soybean oil sample was collected, and the acid values were measured using titrimetric analysis. In addition, the transmission spectra of the samples were obtained for whole test periods. The prediction model for the acid value was constructed by using a partial least-squares regression (PLSR) technique and the appropriate spectrum preprocessing methods. Furthermore, optimal wavelength selection methods such as variable importance in projection (VIP) and bootstrap of beta coefficients were applied to select the most appropriate variables from the preprocessed spectra. Results: There were significantly different increases in the acid values from the sixth days onwards during the 14-day test period. In addition, it was observed that the NIR spectra that exhibited intense absorption at 1,195 nm and 1,410 nm could indicate the degradation of soybean oil. The PLSR model developed using the Savitzky-Golay $2^{nd}$ order derivative method for preprocessing exhibited the highest performance in predicting the acid value of soybean oil samples. onclusions: The study helped establish the feasibility of predicting the rancidity of the soybean oil (using its acid value) by means of a NIR spectroscopy together with optimal variable selection methods successfully. The experimental results suggested that the wavelengths of 1,150 nm and 1,450 nm, which were highly correlated with the largest absorption by the second and first overtone of the C-H, O-H stretch vibrational transition, were caused by the deterioration of soybean oil.