• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.613-617
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• 2001

The test items like as endurance, air leakage and oil endurance test is requested for reliability evaluation about O-ring which is a kind of core machinery accessories of semi-conduct manufacturing equipment. For verification of these, we design and manufactured a test system for endurance, air leakage and oil endurance of O-ring for semi-conduct manufacturing equipment, and also performed the test for two kinds of O-ring, as it were Viton and Kalretz. The characteristics of this test equipment consist in realization of the test conditions of semi-conduct manufacturing equipment and satisfying the test method. The test conditions are cut gas, vacuum grade, temperature and revolution numbers in the endurance test system, vacuum grade and temperature in the air leakage test system, temperature and time in the oil endurance test system. The separating test results for wearing which is an oil endurance test item, the wearing index of domestic produced Viton O-ring is higher than foreign product by 2%, wearing rate of Kalretz O-ring better than Viton O-ring by 17%, and particles existed in various place. The test result of air leakage which is measured through the RGA sensor used Helium, the vacuum grade was $10^-3$Torr. And the test result of oil endurance, the volume change rate was 7~15%. Hereafter, we intend to analysis the reliability test evaluation and to utilize for domestic manufacturing companies by establishing data base and developing reliability softwares.

• 한국자동차공학회논문집
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• 제9권3호
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• pp.42-50
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• 2001

In this paper, the effects of scale formation in engine water jacket upon the thermal durability of engine itself and its component parts were studied. To understand the effect of quality of water, a full load engine endurance test for 50 hours was carried out with not-treated underground water. The followings were found through the tested engine inspection after the endurance test; 1-2 mm thick scale formation in the engine water jacket, valve seat wear, piston top land scuffing, piston pin stick, and cylinder bore scuffing in siamese area. In order to understand the causes of above test results, the heat rejection rate to coolant, the metal surface temperature of combustion chamber, and the oil and exhaust gas temperatures were measured and analyzed. The scale formed in the engine water jacket played a role as thermal insulator. The scale formed in the engine reduced the heat rejection rate to coolant and it caused to increase the metal surface temperature. The reduced heat rejection rate to coolant increased the heat rejection rate to oil and exhaust gas and increased the oil and exhaust gas temperature. Also, the reasons of valve seat wear, piston top land scuffing and cylinder bore scuffing, and piston pin stick quantitatively analyzed in this paper.

• 수산해양기술연구
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• 제35권1호
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• pp.77-82
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• 1999

This study was conducted on the properties of exhaust emissions of diesel oil and fish oil blended with diesel oils using a direct injection diesel engine at different loads, and on the conditions of carbon deposits of diesel oil and 40% blend oil in the combustion chamber after 20 hours operation at $\frac{1]{2}$ load. The properties of exhaust emissions by fish oil blended with diesel oils showed no significant difference with diesel oil. However, soot emissions decreased, increasing the ratio of fish oil. Carbon deposits by fish oil blended with diesel oils were high level compared with diesel oil, which might be overcome by preheating of fuel oil and operating conditions.

• Tribology and Lubricants
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• 제31권6호
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• pp.281-286
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• 2015

Automotive transmission systems are assembled with a large number of gears and shafts, and rolling bearings are used to ensure their smooth operation. Gear oil in the gear box contains solid particles such as wear debris from contacting gears and metallic chips. This particle-enriched lubricating oil can cause premature failure of the rolling bearings. Research aimed at improving the service life of these rolling bearings has been confined mainly to design and lubrication of the inner/outer rings and the rolling elements. In this paper, we redesigned the shape of the cage pocket of a deep groove ball bearing to reduce the premature failure due to particle contamination. Test bearings are assembled with this new cage design containing a hole punched in the cage pocket. Endurance tests are carried out using the contaminated lubricating oil with miracle grid as hard particle. The duration and damaged bearing component shapes are compared for two different cages. The B₁₀ life of bearing with new cage is increased by about 66% compared to the conventional cage. This is because the hard particles can be easily discharged through the pocket hole without staying for a long time in the lubrication regions. This greatly decreases abrasive wear and dents on the highly stressed ball bearing surfaces. Therefore, the cage design of this study, containing a pocket hole, can significantly delay the premature failure of rolling bearings and improve the endurance life.

• Tribology and Lubricants
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• 제11권5호
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• pp.47-54
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• 1995

An advanced liquid lubricants for heat engines has been developed and tested successfully in a prototype engine. The lubricant possesses superior oxidation stability and high temperature stability and is capable of surviving for a minimum of three minutes at 425$^{\circ}$C (800$^{\circ}$C) at the ring zone and maintains stability at an oil sump temperature of 171$^{\circ}$C. The lubricant has been evaluated by the Cummins Engine Co. Out of a field of several dozens of lubricant, six lubricant was selected for a prototype 200 hours endurance testing. The NIST lubricant was one of the two lubricants that successfully finished the endurance testing. This paper describes the key lubricant considerations including oxidation and thermal stability, volatility, deposit control. The engine test conditions and the results will be presented.

• 한국자동차공학회논문집
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• 제22권7호
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• pp.48-56
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• 2014

Engine oil is an oil used for lubrication of various internal combustion engines. The main function is to reduce wear on moving parts; it also cleans, inhibits corrosion, improves sealing, and cools the engine by carrying heat away from moving parts. In engines, there are parts which move against each other. Otherwise, the friction wastes the useful power by converting the kinetic energy to heat. Those parts were worn away, which could lead to lower efficiency and degradation of the engine. It increases fuel consumption, decreases power output, and can induce the engine failure. This study was conducted to evaluate the relation between engine oil property changes and engine performance for the diesel engine. This test was performed by using 12L, 6 cylinder, heavy duty engines. Low SAPS 10W30 engine oil (two type engine oils) was used. Test procedure and method was in accordance with the modified CEC L-57-T97 (OM441LA) method. In this study, TAN, TBN, KV and metal components, engine power, blowby gas, A_F were presented to evaluate the relation with engine oil property changes and engine performance. TAN, TBN, KV and metal We found that the components were generally increased but engine performance did not change. This results mean that property changes did not affect on engine performance because those were not enough to affect engine performance.

• 보존과학회지
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• 제33권2호
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• pp.121-130
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• 2017

현재 야외 철제 조형물 보존용 코팅제로 사용되고 있는 wax는 장점도 있지만 낮은 내구성 및 안정성 등의 단점으로 인한 사용상의 문제점이 노출되고 있다. 손상원인으로는 대기오염에 의한 대기가스와 산성비, 공기 중의 수분, 미세먼지, 황사 등에 의해 wax가 노화되어 코팅력이 저하되고, 이로 인해 보존처리 후 짧은 시간 내에 재 부식이 발생한다. 또한 wax의 노화로 색상변화 및 광택변화가 일어나 표면 이질감을 주기도 한다. 이러한 문제점들은 장기간 지속되어 왔으며 이를 개선하기 위한 재료의 개발이 필요한 실정이다. 이에 본 연구에서는 기존에 사용되어지고 있는 wax 코팅제들을 분석하여 각각의 특성과 용도별로 부족한 점들을 파악하여 보다 개선된 wax 코팅제를 개발하였으며, 야외 폭로실험과 인공 산성비 실험을 통해 환경 변화에 따른 표면 코팅 변화양상을 확인해본 결과 기존 재료들 보다 야외 폭로실험결과 약 4배, 인공 산성비 실험 결과 약 1.5배 이상의 우수한 부식방지 및 차단 효과를 나타내었다. 또한 색도 및 광택도, 접촉각, 박막두께 등의 물성 측정을 통해 기존에 사용되어온 wax보다 박막두께는 약 1.3 ~ 1.8배 두껍지만 고른 피막을 형성해 외부 환경으로 부터의 차단성 및 내구성이 우수하고 색도 및 광택도도 기존의 재료와 유사한 물성을 보여주어 기존에 사용되어온 wax 코팅제를 대체할 수 있는 재료로 판단된다.

• 한국산업보건학회지
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• 제15권3호
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• pp.166-175
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• 2005

Health effects associated with metal working fluid (MWF) exposures include dermatitis, respiratory disease, hypersensitive pneumonitis, and asthma. Frequently, occupational exposures to MWFs are controlled by ventilating an enclosure with an air cleaning unit that includes a fan preceded by various kinds of filtration. There are several kinds of air cleaning units used in machining centers. But the associated troubles have hindered from efficiently using these devices. The main problem is the relatively short period of filter replacement. The reason is that the air cleaning units usually do not have the de-oiling systems, thus leading the earlier clogging of filters and reducing the flow rate of hood. Thus, the first stage of study was conducted to overcome this problem by developing the new oil mist collector equipped with the easy de-oiling system. The principle of de-oiling is that the centrifugal force generated by spinning the drum covered by filter fabric separates oils from the filter fabric. It would be very similar to the spin-dry laundry. By adopting this de-oiling technique, the problems associated with the conventional oil mist collectors could be solved. Several tests/analyses were performed to make the lab-scale oil mist collector. The collection efficiencies and the de-oiling efficiencies of commercially available filter fabrics were tested. Subsequently, the endurance test were conducted by observing SEM photos of filter fabrics and measuring tensile strength/expansion coefficient after spinning the filter drum for 20 minutes at the different rotation speeds. By doing these experiments, the most appropriate filter fabric and rotation speed/duration were selected. Finally, the new oil mist collector was designed. In the near future, this device must be tested in the real machining center.

• 한국자동차공학회논문집
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• 제16권5호
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• pp.37-43
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• 2008

The durability test of turbo-blower for PEM fuel cell is very important process of BOP development. It is a major barrier to the commercialization of these systems for stationary and transportation power applications. Commercial viability depends on improving the durability of the air supply system to increase the reliability and to reduce the lifetime cost. In this study, turbo-blower supported by oil-free bearing is introduced as the air supply system used by 80kW proton exchange membrane fuel systems. The turbo-blower is a turbo machine which operates at high speed, so air foil bearings suit their purpose as bearing elements. The impeller of blower was adopted mixed type of centrifugal and axial. So, it has several advantages for variable operating condition. The turbo-blower test results show maximum parasitic power levels below 1.67kW with the 30,000 rpm rotating speed, the flow rate of air has maximum 163SCFM(@PR1.1). For proper application of FCV, these have to durability test. This paper describes the experiment for confirming endurance and stability of the turbo-blower for 500 hours.

• 대한조선학회지
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• 제9권2호
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• pp.33-42
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• 1972

This paper was studied on the behavior, crack formation and propagation of slip bands on low carbon steel which was heat-treated in three conditions in order to change metallic structure. The specimens were tested by rotating bending fatigue testing machine and also observed the variations of grains by microscope. From the test results it was clear that fatigue endurance limit and life of low carbon steel were more increased in contrast with the case that the grain size of specimen was more decreased. Slip bands developed at oil-quenched specimen and furnace-cooled specimen. Formed cracks in the first one or two grains below the surface were approximately "planar" type, there after they followed "wavy" type. It was also found that cracks at 30% higher stress than fatigue limit were usually developed inter-granular, and cracks at 12% higher stress than fatigue limit were propagated meandering path, partly trans- and partly inter-grandular.