• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.1 s.20
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• pp.49-55
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• 2005

Due to small and light mission payloads, subsystems and propulsion system, small sized UAVs come to be available for reconnaissance that have been performed by aircraft and huge UAVs. The objective of this study is to develop an efficient propulsion system for small reconnaissance UAVs. A glow engine was modified for an efficient and robust 4-stroke gasoline engine with carburetor, new electronic control unit and lubrication system. Engine modification technique and small engine performance test stand are capable of economical method for military UAVs.

• Journal of the korean Society of Automotive Engineers
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• v.4 no.3
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• pp.1-9
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• 1982

자동차에서 윤활을 필요로 하는 부분으로서는 엔진과, 차체 그리고 변속 및 주형장치로 대별되며 엔진만의 윤활을 위해서는 엔진유가 필요하고 차체나 변속 주형장치는 그리이스 및 기어유가 사용된다. 특히 자동차윤활에서 가장 가혹한 조건으로 윤활되고 또한윤활문제로 고심하는 엔진 윤활은 엔진의 구조나 윤활방식 또는 사용연료등엥 따라 윤활상태가 크게 달라질 수도 있으나 윤활이 기본원리와 목적은 대동소이하다. 자동차엔진, 특히 가솔린엔진에서 윤활을 필요로 하는 부분은 베어링, 실린더 및 캠부분등으로 나눌 수가 있으며 이런 부분의 윤활은 극히 가혹한 상태에 놓이게 된다. 따라서 이와 같은 문제들을 고려하면서 가솔린엔진윤활의 제문제점과 엔 진유에 요구되는 성능에 대하여 고찰하여 보고자 한다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1993.12a
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• pp.57-62
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• 1993

To increase the fuel economy, a reduction of friction loss is important in engines. Experimental investigations have been required for reducing the friction loss of crankshaft bearings. Hydraulic cylinder, and servo control ler system which modified the applied load, and test rig for the observation of the characteristics of engine crankshaft bearings were designed and fabricated. Experiment is performed. Friction torque, journal locus and circumferential temperature variations of crankshaft bearings were measured with appling load, revolution speed, and oil inlet temperature, etc.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1987.11a
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• pp.1-27
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• 1987

1. Gasoline engine sludge is a major worldwide problem 2. U.S. and European sludge have similarities 3. Stop-go driving and longer oil drains make the problem worse 4. Fuel is a major influencing factor 5. Increased use of cracked components may be cause 6. Sludge can be peproduced in controlled field tests 7. Daimler benz M102E and ford PV-2 (VE) tests have been developed to overcome problem by higher oil quality 8. The M102E and PV-2 respond in a similar way to increased dispersancy 9. High dispersant ocp viscosity modifiers appear to have unique adbantage in both tests

• Tribology and Lubricants
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• v.28 no.2
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• pp.93-98
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• 2012

The engine oil is an oil 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. In this case, it is possible to cause 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, total acid number, and four-ball test for fresh engine oil and used engine oil after vehicle driving (5000 km, 10000 km). The test result showed that the total acid number and wear scar by four-ball test of used engine oil had increased than fresh engine oil, but 2 kind of used oil (5000 km and 10000 km) had similar physical properties.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.5
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• pp.99-105
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• 2005

Development of an engine with good fuel economy is very important for successful implementation of long endurance miniature UAVs (unmanned aerial vehicles). In the study, a 4-stroke glow-plug engine was modified to a gasoline-fueled spark-ignition engine. Engine tests measuring performance and friction losses were conducted to tune a simulation program for performance prediction. It has been found that excessive friction losses are caused by insufficient lubrication at high speeds. The simulation program predicts that engine power and fuel economy get worse with high altitude due to increasing portion of friction losses. The simulation results suggest quantitative guidelines for further development of a practical engine.

• Tribology and Lubricants
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• v.25 no.1
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• pp.56-60
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• 2009

A journal bearing is used in a hydrodynamic lubrication state, but it becomes a boundary lubrication state that asperity of a contact part touch each other when pressure is too high and an enough oil film is not formed by viscosity change due to lubricating oil temperature. At this time, abrasion due to contact between a journal and a bearing is unavoidable, and scuffing damage that the journal adheres to the bearing occurs if the process is repeated. Damage of the journal bearing is an important problem because it gives huge damage to a machine and can generate large accidents such as economic loss and human life damage. In this study, method for using the pull-up resistor concept was introduced as the monitoring technology. This monitoring system is important to enhance reliability of the engine.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.359-365
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• 1999

We have evaluated the performance and some physical properties of 25 automotive engine oils (21 domestic and 5 imported products) which are purchased on the market to verify the API(American Petroleum Institute) or ILSAC(International Lubricant Standardization and Approval Committee) certification marks attached on the products and to determine the necessity of the quality control of the engine oils on the market. 12 test items are chosen according to API engine oil specification, which are flash point, pour point, cold cranking simulator apparent viscosity, pumping viscosity, gelation index, HTHS(High Temperature High Shear viscosity), foam, high temperature foam, filterability, volatility, high temperature deposit(TEOST), phosphorus content. We have found one product which did not meet the API specification on gelation index, one on HTHS, four on foam, and one on volatility, which implies that the quality control system is in need to check the fidelity of the certification marks attached on the engine oils being marketed. In addition, this works raises the necessity of the upgrade of the present Korean engine oil specification.

• Journal of Applied Reliability
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• v.9 no.1
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• pp.29-35
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• 2009

Due to the excellent durability of Timing Chain, it has been widely used for vehicle engine system. Unlike the timing belt, since the timing chain is operated with the metallic sprocket, the lubrication system is absolutely needed to get this system start. As frequently met at the field, the lubricant has a strong tendency to leak out from the engine due to its severe operating environment. In this paper, results of investigation for thermal movement of aluminum chain cover were described to maximize the sealing ability which is desperately needed at the development stage of engine. Based on these results, some ideas for reproducing the leakage phenomenon and solving methods were proposed.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.04a
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• pp.183-189
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• 1997

This paper presents the motion of dynamically loaded journal in the connecting rod bearing of reciprocating internal combustion engine. Journal motions in engine bearings have been composed of two components, which was rotational and translational motion. Early study of journal locus in engine bearing had been performed on each motion. This paper has been considered two motions simultaneously. Reynolds equation including the squeeze effect has been analyzed using the ADI method, and real engine bearing and crankshaft system has been considered to calculate the cyclic external force. The equations of journal motion have been derived and then the numerical integration of these equations performed by 4th order Runge-Kutta method. This paper gives various journal orbits in connecting rod bearing depending on cyclic external forces, rotating speeds, and bearing parameters.