• 한국정밀공학회지
• /
• 제20권4호
• /
• pp.136-142
• /
• 2003

The morphological analysis of wear debris can provide early a failure diagnosis in lubricated moving system. It can be effective to analyze operating conditions of oil-lubricated tribological system with shape characteristics of wear debris in a lubricant. But, in order to predict and recognize an operating condition of lubricated machine, it is needed to analyze and to identify shape characteristics of wear debris. Therefore, If the morphological characteristics of wear debris are recognized by computer image analysis using the neural network algorithm, it is possible to recognize operating condition of hydraulic driving members. In this study, wear debris in the lubricating oil are extracted by membrane filter (0.45 ${\mu}{\textrm}{m}$), and the quantitative values of shape parameters of wear debris are calculated by the digital image processing. This shape parameters are studied and identified by the artificial neural network algorithm. The result of study could be applied to prediction and to recognition of the operating condition of hydraulic driving members in lubricated machine systems.

• Tribology and Lubricants
• /
• 제10권1호
• /
• pp.69-77
• /
• 1994

Oil flow pass of hermetic scroll compressor with back pressure chamber was described. Dynamic analysis was preceded in order to obtain the loads on the lubricating contacts. The mobility method of dynamically loaded journal bearings was applied to the crank jornal bearing and lower main bearing, and they could be designed to operate under fluid film lubrication. From the consideration of their film thicknesses and oil flow rates, optimal bearing clearances or other bearing dimensions could be assessed. The major friction loss was calculated to be from the axial force between the two scrolls. Therefore, it was suggested that the designers should be careful to reduce the over-turning moment on the orbiting scroll.

• Tribology and Lubricants
• /
• 제15권2호
• /
• pp.131-140
• /
• 1999

This study dealt with some problems occurred in spectrometric oil analysis that has been popularly used for a machine condition monitoring in various fields of industry. One of the problems is that spectrometric technique could not analyze contaminants of large particle (larger than 10 $\mu\textrm{m}$) in lubricating oils. This limitation caused a serious problem in analyzing lubricated machine conditions since wear debris of large size represents better critical machine conditions. In this work, this problem was found to be solved by using a filtration method prior to spectrometric analysis. Another problem could be that spectrometric analysis is incapable of identifying contaminants. This nay mislead the result seriously in practice. This problem was surveyed by analyzing both various types of industrial lubricants and laboratory simulation tests, and the solutions to the problem were suggested in this work.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 1997년도 추계학술대회논문집; 한국과학기술회관; 6 Nov. 1997
• /
• pp.82-87
• /
• 1997

Large dynamic loads act on the rotor in rotary compressors. There are unbalance forces due to eccentric parts and gas forces induced by the pressure difference between compression and suction gases. Rotor-journal bearing system is nonlinear since the stiffness and damping coefficients of the lubricating oil film are not constant in the bearings. The system is considered as a coupled problem of flexible rotor and the journal bearings. Bearing reaction force is calculated from pressure of oil film using Reynolds equations in journal bearings. Pressure distribution in journal bearing is analyzed by finite difference method. The dynamic response of rotor and bearing characteristic are discussed when rotary compressor has a relative misalignment.

• Tribology and Lubricants
• /
• 제28권6호
• /
• pp.315-320
• /
• 2012

For proper functioning, general machines usually need lubricant oil as a cooling, cleaning, and sealing agent at points of mechanical contact. The quality of lubricant oil can deteriorate during operation owing to various causes such as high temperature, combustion products and extraneous impurities. In this study, a heavy load stopped during operation, and the oil was analyzed to check whether any impurities were added. Extraction using acetonitrile followed by reaction with BSTFA(bistrimethylsilyl trifluoroacetamide) showed that, trimethylsilylated ethylene glycol was present in the lubricant oil. To quantify the ethylene glycol in the oil, deuterium-substituted ethylene glycol, which acted as an internal standard, was added to the sample and then extracted with the solvent. Next, the extract was reacted with the derivatizing agent(BSTFA) and then analyzed with GC/MS. The detection limit of this method was found to be $0.5{\mu}g/g$ and the recovery of oil containing $20,000{\mu}g/g$ of ethylene glycol was measured to be 94.8%. A damaged O-ring and eroded cylinder liner were found during the overhaul, which implied the leakage of coolant containing ethylene glycol into the lubricating system. The erosion of the cylinder liner was assumed to be due to cavitation of the coolant in the cooling system.

• 한국화재소방학회논문지
• /
• 제27권6호
• /
• pp.89-96
• /
• 2013

본 연구의 목적은 연소 실험을 통하여 에어컨 실내기의 화염확산에 관한 형상을 관찰하여 화재원인 및 발화지점을 확인하기 위함이다. 본 실험은 화염이 주변으로부터 에어컨 상단에 옮겨 붙는다는 것을 가정하여 실내기 상단을 n-햅탄을 적신 천으로 착화시켰으며, 동일한 조건으로 2회의 반복실험을 하였다. 착화 후 559 s와 734 s 사이에 실내기와 연결된 냉매관이 파열되면서 내부에 충입되어 있던 냉매와 함께 윤활유가 커다란 폭음을 내며 고온 고압의 화염이 급격히 분출되었으며 연소 잔류물을 확인한 결과, 증발기 일부와 모터, 금속함 등을 제외한 대부분은 소실되었다. 에어컨 자체에서 발화되었을 경우와 외부 화염에 의해 소훼되었을 경우 배선의 합선흔적 위치는 유사하였다. 따라서 연소 잔류물의 형상만으로 발화원인과 지점을 특정 짖는 것은 불확실하다는 것을 확인하였다.

• Korean Chemical Engineering Research
• /
• 제54권3호
• /
• pp.332-339
• /
• 2016

본 연구에서는 윤활유 제조기술에 관한 국내외 특허 활동 분석을 통하여 윤활유 제조산업에서의 한국의 기술 경쟁력 분석 및 향후 대응 전략을 제시한다. 이를 위하여 본 연구에서는 한국을 비롯하여 미국, 일본 및 유럽연합 등 윤활유 제조산업에서의 주요 선진국들의 9가지 주요 윤활유 제조기술에 관한 최근 특허 동향을 통계적으로 분석한다. 또한 특허 수, 특허 인용수, 시장확보지수, 특허영향지수, 기술력지수 등 주요 특허 활동 평가 지표 분석을 통하여 한국의 윤활유 제조산업에서의 기술력, 경쟁력 등을 정량적으로 평가한다. 주요 결과로 한국은 뒤늦은 기술개발 등으로 윤활유 제조산업 진입은 상대적으로 늦으나 빠른 국내기술 확보를 통하여 높은 수준의 국내 기술을 보유하고 있다. 반면 상대적으로 낮은 국외 특허 활동으로 인하여 국내 기술의 국외 시장 진출이 용이치 않음을 분석하였다. 이 결과를 바탕으로 친환경 윤활유 시장 및 선진 기술 등 미래 유망 기술 전망 및 한국의 특허 전략을 제시한다.

• 윤활유협회보
• /
• 18호
• /
• pp.12-22
• /
• 1986

국내정유산업의 후방부문인 윤활유사업은 산업의 발전과 함께 국내 진출, 다국적석유기업에 의하여 원료 및 첨가제의 공급에 의한 단순생산과 마아케팅을 하여 국내시장을 지배하여 왔다. 또한 중화학공업의 발달과 함께 산업기계에 요구되는 윤활유제품도 다양화와 품질고급화로 시장구조가 점점 변화되고 있다. 국내윤활유총생산량중 65$\%$의 시장을 가지고 있는 고급윤활유시장은 4개 제조회사에 의하여 96$\%$의 시장을 유지하고 있다. 각 제조회사의 시장확대정책에 의하여 각대리점에 대한 유통경로의 관리가 중요 마아케팅전략음 되고 있는 실정이다. 제조회사의 대형 소비자에 대한 직매, 직영대리점, 일반대리점에 대한 유통기구중 많은 판매비중을 차지하고 있는 일반대리점에 대하여 4P를 기준하여 대리점측 입장에서 마아케팅 믹스를 분석하였다. 제조회사가 판매대리점에 취하는 마아케팅 전략중 직접적인 방법과 간접적인 방법이 시장관리에 나타나는 갈등정도를 가설로 설문지를 작성하여 6월 10일부터 6월 19일까지 경인지역은 조사원에 의한 직접방문과 지방은 등기우편에 의하여 50개 일반대리점에 송부하여 60$\%$의 회수율을 보였다. 응답자료를 통하여 제조회사의 직접적인 시장관리방법과 간접적인 시장관리방법을 사용시 일반대리점에 대한 갈등해소 정도를 상관분석을 통한 통계처리를 하였다. 본 연구결과는 다음과 같은 사실을 얻을수 있었다. 제조회사가 일반대리점에 실시하는 직접적 또는 간접적인 시장관리는 일반대리점에 대하여 갈등해소에 커다란 작용을 하지 못한다. 따라서 제조회사는 유통경로에 대한 전략을 첫째, 일반대리점과 직영대리점과의 시장에 대한 마찰해소 둘때, 대리점에 대한 안정적인 판매이윤제공 셋째, 계획적인 판매대리점간 시장경쟁조정 넷째, R & D 투자강화로 제조회사 차원에서 공동으로 산학협동하여 첨가제 및 상표의 국내개발을 이루어 제품가격인하로 장기적인 시장개발이 요청된다는 결론을 얻었다.

• Tribology and Lubricants
• /
• 제34권6호
• /
• pp.247-253
• /
• 2018

Temperature rise due to viscous shear of the lubricating oil generates hydrodynamic pressure, even if the lubricating surfaces are parallel. This effect, known as the thermal wedge effect, varies significantly with film-temperature boundary conditions. The bearing conducts a part of the heat generated; hence, the oil temperature varies with the thermal conductivity of the bearing. In this study, we analyze the effect of thermal conductivity on the thermohydrodynamic (THD) lubrication of parallel slider bearings. We numerically analyze the continuity equation, Navier-Stokes equation, energy equation including the temperature-viscosity and temperature-density relations for lubricants, and the heat conduction equation for bearing by creating a 2D model of the micro-bearing using the commercial computational fluid dynamics (CFD) code FLUENT. We then compare the variation in temperature, viscosity, and pressure distributions with the thermal conductivity. The results demonstrate that the thermal conductivity has a significant influence on THD lubrication characteristics of parallel slider bearings. The lower the thermal conductivity, the greater the pressure generation due to the thermal wedge effect resulting in a higher load-carrying capacity and smaller frictional force. The present results can function as the basic data for optimum bearing design; however, the applicability requires further studies on various operating conditions.

• 한국산업융합학회 논문집
• /
• 제23권5호
• /
• pp.765-771
• /
• 2020

Automatic lubrication devices are applied in various fields, such as huge machinery, construction machinery or commercial vehicles, to lower maintenance costs and protect the devices. In addition, the automatic lubrication device reduces frequent component failures cause by friction and allows the machine to replace the lubricating oil replenishment work carried out by the manager. However, the automatic lubricating device used in large machinery or commercial vehicles is relatively large, containing a large amount of lubricant in the space to be lubricated. On the other hand, a smart factory, such as a home appliance or cosmetics factory, lacks space to install large automatic lubrication devices, and it is difficult to distribute electricity. Therefore, there is a need for an automatic lubrication device that can be used in various environments that require lubrication. In this paper, a small automatic lubrication device is proposed for smart factories that have changed parts of existing factories, such as electronics factories, to minimize friction arising from mechanical parts, etc. In particular, the structure of lubricating pumps and component parts that are the core of automatic lubrication devices was described so that they could be utilized in various fields. Finally, a test bed environment is established for the proposed automatic lubrication device to evaluate its performance and verify its applicability.