• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.2
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• pp.64-69
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• 2010

We investigated the variation in contact angle of a nano-sized water droplet on a nano stripe-patterned surface using molecular dynamics simulation. By changing the height and width of the stripe pillar, and the gap width of the stripes, we observed the contact angle of water droplet in equilibrium. When the surface energies were 0.1 and 0.3 kcal/mol, the calculated contact angles were in good agreement with the Cassie and Baxter equation. However, when the surface energy is 0.5 kcal/mol, the contact angles are observed to be perturbed along the Cassie and Baxter equation.

• Tribology and Lubricants
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• v.25 no.1
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• pp.38-42
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• 2009

Gear is an essential component of an automotive. Crowning is used for tooth modification of a gear. The basic concept of gear tooth crowning is to reduce the stress concentration in edge of contact area and appropriate profile modifications can help gears to resist scoring, pitting, and tooth breakage. In this study, a method to determinate spur gear tooth crowning amount to make smooth surface stress and subsurface stress distribution is proposed. This method is based on the contact analysis.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.499-502
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• 2006

This paper presents computed results of FEM analysis on the tribological contact behaviors of a primary sealing components of mechanical face seals for a small hydro-power turbine. The FEM computed results present that the contact area between seal rings and seal seats is very important for a good tribological performance such as low friction heating, low wear, high contact normal stress in a primary seal ing components. Based on the FEM computation, model III in which has a small sealing contact area shows low dilatation of primary sealing components, and high contact stress between a seal ring and a 1)seal seat.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.6
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• pp.435-440
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• 2014

Contact-guided-wave tests are impractical for investigating specimens with limited accessibility and rough surfaces or complex geometric features. A non-contact setup with a laser-ultrasonic transmitter and receiver is quite attractive for guided-wave inspection. In the present work, we developed a non-contact guided-wave tomography technique using the laser-ultrasonic technique in a plate. A method for Lamb-wave generation and detection in an aluminum plate with a pulsed laser-ultrasonic transmitter and Michelson-interferometer receiver was developed. The defect shape and area in the images obtained using laser scanning, showed good agreement with the actual defect. The proposed approach can be used as a non-contact online inspection and monitoring technique.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.989-998
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• 2023

Under nuclear reactor severe accidents, the resuspension of radioactive aerosol may occur in the containment due to the disturbing airflow generated by hydrogen combustion, hydrogen explosion and containment depressurization resulting in the increase of radioactive source term in the containment. In this paper, for containment conditions, by considering the contact between particle and rough deposition surface, the distribution of the distance between two contact points of particle and deposition surface, rolling and lifting separation mechanism, resuspension model based on random contact with rough surface (RRCR) is established. Subsequently, the detailed torque and force analysis is carried out, which indicates that particles are more easily resuspended by rolling under low disturbing airflow velocity. The simulation result is compared with the experimental result and the prediction of different simulation methods, the RRCR model shows equivalent and better predictive ability, which can be applicable for simulation of aerosol resuspension in containment during severe accident.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.7
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• pp.1581-1589
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• 1995

The feasibility of using AE for detecting contact and slip between a workpiece and an end effector has been tested. Specifically, the relationship between the contact and slip motion and the characteristics of the AE signal is theoretically and experimentally investigated. The experimental results manifest that the high sensitivity of AE signal to the contact and slip makes it a good alternative as a robot tactile sensor.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.3
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• pp.345-352
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• 2013

In this research, a study on stress shape functions was conducted to analyze the contact stress problem by using a hybrid photoelasticity. Because the contact stress problem is generally solved as a half-plane problem, the relationship between two analytical stress functions, which are compositions of the Airy stress function, was similar to one of the crack problem. However, this relationship in itself could not be used to solve the contact stress problem (especially one with singular points). Therefore, to analyze the contact stress problem more correctly, stress shape functions based on the condition of two contact end points had to be considered in the form of these two analytical stress functions. The four types of stress shape functions were related to the stress singularities at the two contact end points. Among them, the primary two types used for the analysis of an O-ring were selected, and their validities were verified in this work.

• 한국가스학회:학술대회논문집
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• 2005.10a
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• pp.226-232
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• 2005

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.12
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• pp.2261-2267
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• 1992

The equations are derived for the evaluation of the axial contact force. The contact forces for rubber seals are analyzed as a function of the ratio of real contact length, the thickness of seal lip, the inclined angle of seal lip, and the interference between the edge of seal lip and the rotating inner ring. The design data for rubber seals are presented in terms of the ratio of real contact length, initial inclined lip angle, lip thickness and the interference. The calculated results show that the deflected interference and the circumferential stress cause considerable change of contcat forces for the low sealed pressure.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.339-349
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• 2004

The method for fatigue life prediction of ball bearing is proposed applying the algorithm of contact fatigue prediction based on stress analysis. In order to do this, a series of simulation such as initial surface stress analysis, EHL analysis, subsurface stress analysis and fatigue analysis are conducted from the loading at each ball location calculated for a bearing subjected to external bearing load and contact shape function. And uniaxial fatigue tests are performed to obtain fatigue parameter of AISI 52100 steel. It was found that since stress is usually higher at the inner raceway contact than at the outer raceway contact, fatigue failure occurs on the inner raceway first. When the fatigue life calculated in the stress-based method are compared with $L_{50}$ life of L-P model, Crossland criterion for the radial load increment is similar to $L_{50}$ life and Dang Van criterion for the axial load increment is similar. In the case of EHL contact. there is no difference of fatigue life between dry contact and EHL contact, when maximum Hertz pressure exceeds 2.5GPa.