• Journal of the Korean Applied Science and Technology
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• v.34 no.1
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• pp.12-24
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• 2017

The main purpose of this research is for the investigation on the impact of engine oil aging on PM and DPF. It is widely known that lubricant specifications and consumption from an ICE have significantly influenced on the regulated and unregulated harmful emissions as the engine operating conditions. Considering DPF clogging phenomena with lubricant-derived soot/ash components, simulated aging mode for the DPF was newly designed for engine dynamometer testing. PM/ash accumulation cycle were developed in reflecting real-world engine operating conditions for the increment of engine oil consumption and natural DPF regeneration for the ash accumulation. The test duration for DPF aging reached around 100hrs with high- and low-SAPS engine oils, respectively. Using high SAPs engine oil made more PM/ash accumulation compared with low SAPs engine oils and it could accelerate fouling of EGR in engine. Fouling of EGR made effects on more harmful exhaust gases emissions. The test results on engine lubricant under engines operating conditions will deliver for the establishment of regulated and unregulated toxic emissions policy, lubricant quality standard.

• The Journal of Dong Guk Oriental Medicine
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• v.9
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• pp.35-49
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• 2000

Purpose: This study is to investigate the alleviation effects of Daebangpoongtang in LPS induced arthritis in mice knee joint. Methods : Daebangpoongtang was chosen to treat the arthritis caused by injecting $300{\mu}g/kg$ LPS to mice knee joint. The control group had no treatment, while the LPS group was injected $300{\mu}g/kg$ LPS to mice knee joint and the DBP group was oral administrated of Daebangpoongtang. After injection of $300{\mu}g/kg$ LPS to mice knee joint, the alteration of synovial lining cell, vessel, fibrosis, distribution of collagen fiber, fibroblast, mast cell, infiltration of inflammation component cell and distribution of ICAM and VCAM was observed by light microscope(BX50). Results : In the DBP extract treatment group, the distribution of vessel, the enlargement of synovial lining cell layer, the synovial lining cells with filopodia, the fibrosis, the distribution of fibroblast in synovial membrane, the distribution of TCAM and VCAM on the knee joint was less than that of LPS group. Infiltrated lymphocyte into the apical surface had not observed in the DBP extract treatment group. The distribution of mast cell was as same as control group(no treatment group) and it showed granulated type. Conclusion: According to the above results, it might be considered that the administration of Daebangpoongtang has a curative effect on synovial membrane injury in arthritis by inhibiting increase of vessel, cell adhesion molecule(ICAM and VCAM) in LPS induced arthritis.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.5
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• pp.35-42
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• 2014

The influence of sine wave striated surface roughness on load carrying capacity of a bearing is studied for thin film effect of slider bearing. A Reynolds equation appropriate for slider bearing is used in this paper for analysis and it is discussed using finite difference method of central difference scheme. For a slider bearing with sine wave simple roughness form, several parameters such as pressure, load capacity and shear stress of the bearing can be obtained and also this results can be stored in sequential data file for latter analysis. After all, their distribution can be displayed and analyzed easily by using the matlab GUI technique. The parameters such as amplitude, number of waviness and slope of the surface are used for discussing the load carrying capacity of the rectangular bearing. The results reported in this paper should be applied to the other slider bearing such as rectangular or round embossed surface of slider bearing.

• Tribology and Lubricants
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• v.30 no.5
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• pp.284-290
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• 2014

The influence of round embossed surface on slider bearing characteristics and its load carrying capacity is discussed for thin film effect of embossed slider bearing. For the numerical computation of lubrication parameters such as pressure, load capacity and shear stress that are normalized and a Reynolds equation is used for the analysis of embossed slider bearing characteristics. For this purpose, the finite difference method of central difference scheme is used in this study. In a slider bearing with embossed form, several simulation parameters such as pressure, load capacity and shear stress of the bearing can be obtained according to independent parameters such as the slope of the slider bearing and number of embossing in the upper slider. Also this results can be summarized and be stored in sequential data file for latter analysis. After all, their distribution of the pressure and shear stress parameters can be displayed and be analyzed easily by using the developed program with matlab GUI technique. The independent parameters such as a number of embossing and a slope of the embossed surface slider are used for discussing simulation parameters of pressure distribution, shear stress and load carrying capacity of the round embossing. These study results reported in this paper should be applied to the other shaped slider bearing with a rectangular embossed surface or rectangular waved surface.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.634-643
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• 2020

In this study, the rheological and tribological properties of urea grease were studied according to the type and amount of polytetrafluoroethylene (PTFE) powders added to the urea grease, which is the most widely used among solid lubricants, to develop an optimal lubrication system. Urea grease was synthesized using 4,4'-methylenebis(phenyl isocyanate)(MDI), oleylamine, and cyclohexylamine, and PTFE powders prepared by dispersion or suspension polymerization process were then added. The basic rheological and tribological properties of the prepared greases were compared. The worked penetration numbers of urea grease decreased with increasing amount of PTFE powders, but both PTFE powders caused no significant changes in heat resistance and copper corrosion resistance. The shear viscosity increased with increasing PTFE powder content, and the dispersion-type PTFE powder was more effective in increasing the viscosity. In the value of the loss coefficient = 1, the shear stress was higher for the grease containing PTFE powders than the non-PTFE added grease, and the dispersion-type PTFE-added grease showed higher viscosity than the suspension-type PTFE-added grease. Finally, urea grease was found to have a low-performance improvement in terms of wear reduction effects by adding PTFE powders, but the load-bearing performance was up to 2.5 times higher for the dispersion-type PTFE and five times higher for the suspension-type PTFE.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.108-110
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• 2008

다이아몬드마이크로블레이드의 윤활제첨가에 따른 절삭 성능과 수명향상을 위해 절삭에 따른 블레이드의 마모량을 측정시험을 행하였고 블레이드의 절삭성능을 평가할 수 있는 지표인 일정속도로 절삭 중 블레이드의 전력소모량을 측정하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.5
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• pp.625-630
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• 2013

The friction behavior of a 60-${\mu}m$-thick anodic aluminum oxide (AAO) film having cylindrical nanopores of 45-nm diameter was investigated as a function of impregnated oil viscosity ranging from 3.4 to 392.6 cSt. Reciprocating ball-on-flat sliding friction tests using a 1-mm-diameter steel ball as the counterpart were carried out with normal load ranging from 0.1 to 1 N in an ambient environment. The friction coefficient significantly decreased with an increase in the oil viscosity. The boundary lubrication film remained effectively under all test conditions when high-viscosity oil was impregnated, whereas it was easily destroyed when low-viscosity oil was impregnated. Thin plastic deformed layer patches were formed on the worn surface with high-viscosity oil without evidence of tribochemical reaction and transfer of counterpart material.

• Journal of Navigation and Port Research
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• v.44 no.6
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• pp.453-459
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• 2020

A sea trial of the speed performance test is the one of the most important means of verifying a ship's performance, and the International Organization for Standardization established a standard for this test in 2015. Environmental disturbances such as wind and waves are always present under real sea conditions, however, so it is impossible to accurately estimate delivered horsepower under ideal conditions. These disruptive influences also make it difficult to evaluate the positive effect of recently developed energy-saving devices. In this study, uncertainty analysis of improved speed performance was carried out using Monte Carlo simulation to confirm the energy-saving efficiency of a ship equipped with an air-lubrication system. The findings showed the average power saving to be 3.2%, with the expanded uncertainty of ± 2.7% at a 95% confidence level (k=2).

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.129-134
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• 1997

현재 외부 가압 공기베어링이 사용되어지는 분야는 PCB 기판, 엔진의 연료분사노즐 등의 고속가공용 스핀들, 전자 기기, 광학 기기 등에 사용되는 초정밀 부품가공용 스핀들, 정밀 측정 기기, 의료 기기, 저온 팽창기등 상대운동을 하는 많은 분야에서 이용되고 있으며, 이들 분야의 고속화 및 고정밀화 추세에 따라 고속에서의 안정성과 높은 운전정밀도가 보장된 외부 가압 공기 베어링이 요구되고 있다. 정밀 스핀들 시스템에 공기베어링이 사용되는 이유는 윤활제인 공기의 압축성에 기인된 평균화효과로 인하여 어느 정도 형상오차가 존재하더라도 축의 회전 시 떨림 진폭이 흡수되어 높은 운전정밀도를 유지하며 운전이 가능하기 때문이다. 그러나, 공기의 압축성에 의한 평균화효과로 어느 정도의 떨림 진폭은 흡수되나 형상오차에 의한 떨림 진폭은 작은 크기라도 여전히 남아있게 된다. 따라서, 초정밀 가공 기기나 정밀 측정 기기 등 높은 운전정밀도가 요구되는 곳에 공기베어링이 사용될 경우에 있어서 형상오차는 운전정밀도에 영향을 미치는 중요한 인자가 된다. 본 연구에서는 각각 두 개의 오비 가압 공기 저널 및 스러스트 베어링으로 구성된 스핀들 시스템에 대한 축과 베어링의 직각도 오차가 운전정밀도에 미치는 영향에 대해 해석하고 결과를 고찰하여 스핀들 시스템에 있어서 형상 공차에 대한 기초 설계자료를 제시하고자 한다.

• Journal of Industrial Technology
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• v.28 no.A
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• pp.195-198
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• 2008

Graphite and $MoS_2$ were added respectively to the Cu/Sn bond materials of the same composition as a lubricant in order to find out the effect of lubricants on the mechanical properties and the increase in density of the sintered products for microblades. The addition of $MoS_2$ as a lubricant was more beneficial to strength, fracture toughness, and hardness as well as densification than graphite. $MoS_2$ seemed to be more effective in reducing the friction between the metallic powders and die wall during hot pressing process. Due to the better wettability of MoS2 with bond metal alloy, less amount of interfacial defects which is detrimental to mechanical properties use observed.