• Tribology and Lubricants
• /
• v.14 no.1
• /
• pp.54-63
• /
• 1998

In many practical lubricated contacts such as a rough concentrated contact on the sliding of nominally flat surfaces, the fluid may be of molecular (nanometer) scale owing to the asperity interactions on the surfaces. Under this condition, there is insufficient lubricant on the concentrated contact spot to maintain a realistic continuum. Rheological behavior for this kind of concentrated contact has been studied extensively to know whether the application of viscous fluid model is appropriate. The interaction of two rough surfaces is simplified as perfectly flat-rough surfaces contact under certain conditions by "composite topography" and for a nanometer scale fluid film, three kinds of rheological fluid behavior are analyzed in elastohydrodynamic asperity point contact.t contact.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1997.10a
• /
• pp.173-182
• /
• 1997

In many practical lubricated contacts such as a rough concentrated contact on the sliding of nominally flat surfaces, the fluid may be of molecular (nanometer) scale owing to the asperity interactions on the surfaces. Under this condition, there is insufficient lubricant on the concentrated contact spot to maintain a realistic continuum. Rheological behavior for this kind of concentrated contact was studied to know whether the application of viscous fluid model is appropriate. The interaction of two rough surfaces is simplified as perfectly flat-rough surfaces contact under certain conditions by "composite topography" and for a nanometer scale fluid film, three kinds of rheological fluid behavior are analyzed in elastohydrodynamic asperity point contact.t contact.

• Asia Marketing Journal
• /
• v.20 no.2
• /
• pp.41-63
• /
• 2018

Incidental envy influences behavior in various domains. However, no research, to date, has investigated whether incidental envy influences interpersonal behavior toward others who are unrelated to the emergence of the emotion. That is, the literature is silent on how those who experience incidental envy engage in interpersonal contact and how this may affect consumers. In this paper, we address this question by investigating the influence of incidental envy on interpersonal contact with others of higher or lower status based on the social comparison theory. We demonstrate that incidental envy (versus a neutral emotion) motivates people to contact higher status others to facilitate upward assimilation (experiments 1 and 2). We also show that when competition (a situational factor that heightens the personal relevance of the interaction with the target) is involved, individuals who feel envy (versus a neutral emotion) are more likely to contact lower status others to engage in downward contrast (experiment 3). We conclude with a discussion of the practical implications of our findings.

• Korean Journal of Human Ecology
• /
• v.3 no.1
• /
• pp.40-50
• /
• 2000

The purpose of this study is to investigate the influential variables related to the value orientation and environmental preservation behavior. This study is also to provide data for environment education. The subjects were 538 children, in June. 1998, in Kwangju. The data obtained were analyzed by Pearson's correlation. Cronbach's u coefficient. multiple regression. and Path analysis. The major findings were as follows : 1) The influential variables for childrens'egoistic value orientation were grade level of children and education level of mother The influential variables for childrens'altruistic orientation were the frequency of contact for environmental information and age of mother. The influential variables for childrens'biospheric orientation were education level of mother and the frequency of contact for environmental information. 2) The influential variables for the childrens'behavior on the environmental preservation were the frequency of contact for environmental information. biospheric orientation. grade level of children and education level of mother.

• Journal of the Korea Convergence Society
• /
• v.9 no.1
• /
• pp.283-289
• /
• 2018

In automotive disc brake systems, frictional heat is not uniformly dispersed for reasons such as heat flux and thermal deformation. The thermoelastic deformation due to the frictional heat affects the contact pressure distribution and the contact load may be concentrated on the contact portion on the the disc brake surface, resulting in thermoelastic instability. In this study, thermal analysis and thermal deformation analysis considering the contact between disk and pad occurred during braking through 3D axial symmetry model with reference to the experimental equation and Kao's analysis method of contact pressure of disk and pad. ANSYS is used to analyze the thermal and elastic instability problems occurring at the contact surface between the disk and the pad, considering both the thermal and mechanical loads. A 3D axisymmetric model with direct contact between the disk and the pad was constructed to more accurately observe the thermal behavior of the disk by observing the frictional surface temperature, thermal deformation and contact thermal stress of the disk.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.19 no.2
• /
• pp.249-263
• /
• 2017

The expansion behavior of inflatable steel pipe rockbolt shows geometric nonlinearity due to its ${\Omega}-shaped$ section. Previous studies on the anchoring behavior of inflatable steel pipe rockbolt were mainly performed using theoretical method. However, those studies oversimplified the actual behavior by assuming isotropic expansion of inflatable steel pipe rockbolt. In this study, the anchoring behavior of the inflatable steel pipe rockbolt were investigated by the numerical method considering the irregularity of pipe expansion and other influencing factors. The expansion of inflatable steel pipe rockbolt, the contact stress distribution and the change of the average contact stress and the contact area during installation were analyzed. The contact stresses were developed differently depending on the constitutive behavior of rocks. Small contact stresses occurred in steel pipes installed in elasto-plastic rock compared to steel pipes installed in elastic rock. Also, the anchoring behaviors of the inflatable steel pipe rockbolt were different according to the stiffness of the rock. The steel pipe was completely unfolded in the case of the stiffness smaller than 0.5 GPa, but it was not fully unfolded in the case of the stiffness larger than 0.5 GPa for the given analysis condition. When the steel pipe is completely unfolded, the contact stress increases as the rock stiffness increases. However, the contact stress decreases as the rock stiffness increases when the steel pipe is not fully expanded.

• Journal of the Korean Society of Visualization
• /
• v.18 no.1
• /
• pp.18-25
• /
• 2020

The droplet impact behavior is dominated by some parameters such as surface temperature, We number, surface and fluid property. Especially, Leidenfrost effect which prevents the contact between surface and droplet is very powerful phenomenon for determining droplet impact behavior. Due to this effect, the impact regime is divided into contact boiling regime and film boiling regime whether the droplet contact with the surface. Many studies have found that surface micro-structures which processed by surface processing are effective to overcome the Leidenfrost effect. In this study, droplet impact behaviors were compared using ethanol both on flat and laser-ablated Al surface. On the flat surface, impact regime was mainly divided by surface temperature. And there is key dominant parameter for each regime. On the laser-ablated surface, we could see changed impact regime and different impact behavior such as jetting and ejection of tiny droplets despite of same impact conditions.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.19 no.1
• /
• pp.125-132
• /
• 2011

The dynamic characteristics of valve train are responsible for the dynamic performances of engine. We derived the equation of motion for 6 degrees of freedom model of the valve train. Computer model is also developed with flexible multibody model considering contact between components. The simulation results with these two models are compared with experimental results. We investigated the effect of the two spring models, TSDA (Translational Spring Damper Actuator) element and flexible body model, on the valve behavior and spring force. It is found that the dynamic behavior of the two models are not very different at normal operational velocity of the engine. By modeling contact between cam and tappet, the stress distributions of the cam were found. Using stress distribution obtained, contact width and contact stresses of the cam surface were calculated with Hertz contact theory.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2002.10b
• /
• pp.121-122
• /
• 2002

This paper presents contact behavior of an Polyperfluoroalkoxyethylene(PTFE) ring seals by a non-linear finite element method using the thermomechanical analysis. PTFE elastomer was assumed as odgen model for numerical analysis in FEM commercial code because elastomer has nonlinear behaviour character. The shape effects are investigated for sealing performance of ring seal in boundary conditions which as gas pressure, groove temperature and various O-ring seal models. Also contact stress and equivalent total strain are investicated. An O-ring seals was modeled four shape which are circle, two sunflower and X. The highest contact stress occurs at sunflower-ring seal with groove deapth of 0.35mm. the equivalent total strain of sunflower-ring seal is lower than that of the others under low gas pressure condition but under gas pressure condition over 4Mpa, that of sunflower-ring seal is higher. The calculated FEM results shows that the Sunflower-ring seal with groove depth of 0.35mm has excellent performance compared with other seal models.

• Proceedings of the KSR Conference
• /
• 2009.05b
• /
• pp.225-230
• /
• 2009

From the view point of railway vehicle dynamics, the interaction between wheel and rail have an huge effect on the behavior of the vehicle. This phenomenon is an unique motion, only for railway vehicles. Furthermore, close investigation of the backgrounds of the interaction is the key to estimate the dynamic behavior of the vehicle, successfully. To evaluate the model including flexible bodies such as car body and catenary system of the next generation express train, it is necessary to develop proper dynamic solver including a wheel rail contact module. In this study, wheel-rail contact module is developed using the general purpose dynamic solver. First of all, the procedure for calculation of the wheel-rail contact force has been established. Generally, yaw angle of the wheelset is ignored. Sets of information are summarized as tables and splined for further uses. With this information, normal force and creep coefficient can be extracted and used for FASTSIM algorithm, which has been shown good reliability over years. Normal force and longitudinal, lateral force at the contact surface are also calculated. Those data are verified by commercial railway simulation program 'VAMPIRE'. This procedure and program can offer a basic process for estimation of the dynamic behavior and wear of the wheel-rail system, even while running on the curved rail. Finally, multi-dimensional inspection tool will be developed including the prediction of the derailment.