• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.5
• /
• pp.657-666
• /
• 2017

In this study, factor analysis was performed to reduce the friction in the elevation motion of a stand for a 50-inchtelevision. Pipe type cross-section control was used for accurate positioning control of the piston rod. The pipe type was also compared with a labyrinth-type crosssection for the orifice. The frictional force was then reduced using gas seal lip technology. Specifications were chosen, and a volume compensation experiment was carried out using an apparatus for compensating the volume of the cylinder, which is compressed by the volume of the piston rod. Based on CAE and experimental considerations, the labyrinth-type orifice is preferred for reducing friction. For the gas seal lip technology, outer and inner diameters of ${\Phi}20$ and ${\Phi}8$ for the hollow rod were more appropriate when assuming the weight of a 50-inch television to be 30kgf. The third is that the result of total consideration in stability problem and performance of volume compensation for specification decision and volume compensation experiment is determined the final speculation of hollow rod ?8x?4 and riveting system. The last is that the labyrinth orifice is not founded that of the ${\O}0.4{\sim}0.6$ orifice both tests on 300 mm intervals.

• The Journal of Engineering Geology
• /
• v.31 no.3
• /
• pp.357-366
• /
• 2021

Shear behavior dependent on the shape and roughness of rock joints can greatly influence the stability of the ground and rock structures. The efficient design of rock structures requires understanding of the shear behavior due to joints and accurate calculation of the shear strength. This work reports numerical shear tests using PFC2D on No. 1 (JCR-1), with smooth joints, and No. 7 (JRC-7) and No. 9 (JRC-9), with relatively rough joints, for the 10 shapes of standard joint profiles proposed by Barton and Choubey (1977). The aim was to investigate the shear behavior of rock joints with respect to their roughness. The results show the maximum shear stress to be about 3.2 to 5.0 times greater in the rougher JRC-7 and JRC-9 joints than in smoother JRC-1. The maximum shear displacement was approximately 4.1 to 5.8 times greater at the first normal stress than at the second. The rougher joints showed friction angles of the rock joints that were approximately 1.8 to 3.9 times greater than that in the smooth joint. Overall, increasing the rock joint roughness increased the maximum shear stress and friction angle.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.12
• /
• pp.1035-1042
• /
• 2014

Reducing the friction of engine parts is an important issue in engine design. The loss of energy in the piston assembly due to mechanical friction ranges from 40 to 55%, and there is an increase in the total energy of about 5% if the friction of the piston can be removed. In order to reduce the friction loss at the level of each engine part, it is necessary to perform a comparative analysis with other engines to determine the important factors affecting the energy loss. Several studies have been performed to analyze the lubrication based on hydrodynamic modeling, since a piston lubrication system has dimensions in the nanoscale to microscale domain. Therefore, it is necessary to determine the correlations between the molecular and continuum systems. In this study, we investigated the friction changes due to the various interactions between molecules in the wall/fluid interface, where a microscopic movement of the oil film occurs along the cylinder liner of the engine.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.12 no.2
• /
• pp.113-119
• /
• 2019

We have developed the multi-functioned friction measuring instrument for the previous research. In here, we improved the performance of friction measuring instrument by applying the adaptive smoothing method and analyzed the friction of plate and monitoring function of friction surface through scratch tests. We substituted lubricant steel plate to lubricant oil used for reducing the friction when fabricating steel plate because lubricant oil was regarded as one of the major causes for the environmental pollution. In particular, the functions of various plate such as galvannealed steel sheets were analyzed because friction coefficient could be changed depending on the type of organic/inorganic plate or state of coating layer. Therefore, we demonstrated that adaptive smoothing method could enhance the accuracy of measuring instrument which eliminate the noise. As a result of using the method, it showed the reduction rate 0.0417% for the friction coefficient 0.16.

• Geotechnical Engineering
• /
• v.12 no.3
• /
• pp.5-16
• /
• 1996

Based on many experimental results on fine silica sands, the strength relation between triaxial and plane strain tests is expressed as a function of both density and mean effective principal stress at failure. Stress ratio of mean normal stress to deviatoric stress at failure is a well defined function of shear angle of friction, This ratio decreases with increasing shear angle of friction. Intermediate principal stress is also expressed in terms of major and minor principal stresses and a relatively good agreement between theoretical and observed angles of failure plane in plane strain test is confirmed.

• Journal of Ocean Engineering and Technology
• /
• v.6 no.1
• /
• pp.19-28
• /
• 1992

The motion of a cylindrical object resting on shallow seabed due to wave forces and soil friction is studied. Given environmental conditions such as wave characteristics and seabed soil properties, the equations of motion are derived and the corresponding reponses of the cylinder in two dimensional plane, i.e., translational and rotational displacements, accelerations, are calculated. The motion is substantially restrained by the penetration of a cylinder into seabed and the parametric study focuses on finding out a minimum penetration depth which makes the cylinder motionless.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.6 no.3
• /
• pp.38-46
• /
• 2007

Weight reduction for an automobile component has been sought to achieve fuel efficiency and energy conservation. In response to this trend, a new disc-brake called the circumferential friction disc-brake is suggested. This paper compares the mechanical performances of a conventional disc-brake and a suggested disc-brake, under the dynamic braking condition. The thermoelastic instability is considered to simulate the test condition. Furthermore, the metamodel using kriging interpolation method is introduced to obtain the optimum design of a suggested circumferential friction disc-brake. The design results obtained by the kriging method are compared with those obtained by the ANSYS.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2015.11a
• /
• pp.283-283
• /
• 2015

현재 LAC 베어링에 적용되는 표면 처리는 일반적으로 하드터닝+슈퍼피니싱 가공이 적용되고 있고, 장수명을 위한 표면 처리 기술이 보다 더 요구되는 추세이다. Burnishing 기술은 매끄럽고 단단한 공구를 베어링 궤도면에 충분한 압력을 가하여 서로 문질러(rubbing) 마찰면을 소성 변형시켜 표면 거칠기 및 압축 잔류 응력 등을 향상 시키는 기술이며, 베어링과 같은 금속의 경우 버니싱 가공 적용 시 광택을 띠는 특성을 가지므로 외관 품질 향상에 기여하므로 슈퍼 피니싱 공정을 대신할 수 있다. 또한 표면 finishing, 표면 경도, 내마모성 및 피로/부식 저항성을 향상시킨다. 이에 본 연구에서는 슈퍼 피니싱 가공을 대신하기 위한 버니싱 가공의 물성을 검토하였고, 다른 공정과의 비교를 통한 버니싱 기술의 효과 확인하였다.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2000.11a
• /
• pp.289-297
• /
• 2000

The determination of surface topography is believed to be extremely important in the areas of contact mechanics, adhesion and friction. In order to describe topography of various frictional surface, the harding test was carried out under different experimental conditions in try friction. And fractal descriptors was applied to frictional surface of laser modified steel with image processing system These descriptors to analyze surface structure are fractal dimension. Surface fractal dimension can be determined by sum of intensity difference of surface pixel. Topography of frictional surface can be effectively obtained by fractal dimensions.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.05a
• /
• pp.140-140
• /
• 2004

마이크로 기술을 대변하는 Micro-Electro-Mechanical-Systems (MEMS)와 반도체, 각종 micro-sensor 및 actuator 등은 실리콘 위에 박막 코팅한 재료를 주로 사용하고 있다. 따라서 1 Um 이하의 박막코팅에 의해 원하는 성능을 얻으려는 시도가 널리 진행되고 있다 Hard Disk Drive (HDD)의 Head-Disk Interface (HDI)와 MEMS 접촉면에서는 발생하는 마찰 및 마멸에 대한 문제 등은 중요한 고려대상이다. 특히 코팅 층의 표면 파손 현상은 코팅 층의 파손 특성과 코팅 층과 기판 사이의 결합상태가 큰 영향을 미친다.(중략)