• Journal of the Korean Society for Precision Engineering
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• v.27 no.8
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• pp.20-27
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• 2010

A precise evaluation of the contact position and the distribution of contact pressure in a wheel-rail interface analysis is one of the most important procedures to predict fatigue life and wear of wheel and rail. This paper presents the analysis result of finite element method(FEM) to investigate how the deformation of a wheelset, which is the assembly of wheel and axle of a railroad vehicle, affect the contact analysis of wheel and rail. 3D-FEM was used to analyze three contact models; a model with only wheel, a model with wheelset, and a model with simplified wheel and rail geometry. The analysis result of the contact position and the distribution of contact pressure are discussed. It is shown that the analysis results of a model with wheelset represent largest value with respect to contact pressure and contact stress. Furthermore, it is found that the distribution of contact pressure and the contact position is highly affected by the deformation of wheel and axle. It is concluded that the deformation of axle should be considered to evaluate the exact contact parameters in a wheel-rail contact analysis.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.4
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• pp.59-65
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• 2010

This paper presents the study on the contact stress analysis of a pair of mating spur gears during rotation. Contact stress analysis is performed between two spur gear teeth at different contact positions during rotation. An example is presented to investigate the variation of contact stress on a pair of mating gears with contact positions. The variation of contact stress during rotation is compared with the contact stress at lowest point of single tooth contact(LPSTC) and AGMA Equation for contact stress. The results show that contact stress varies along the contact position and gets maximum values in the beginning and end of the contact. In this study, the gear design considering the contact stress on a pair of mating gears is more severe than that of AGMA standard.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.6
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• pp.152-159
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• 2001

In multibody dynamic analysis including contact and impact, there are two major analysis methods, i.e., piecewise analysis and continuous analysis. Modeling of contact phenomena is mainly classified with a Kelvin-Voigt model or a model of Hertz contact model. In this paper, a contact module fur AutoDyn7 program was developed and implemented. Both the Kelvin-Voigt model and a model of Hertz contact law were developed. The process of this module is composed of contact distinction and the contact force calculation. Two examples were verified and compared to the commercial program DADS.

• Structural Engineering and Mechanics
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• v.53 no.5
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• pp.1051-1066
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• 2015

The study aims on the effect of material dependency in elastic- plastic contact models by contact analysis of sphere and flat contact model and wheel rail contact model by considering the material properties without friction. The various materials are selected for the analysis based on Young's modulus and yield strength ratio (E/Y). The simulation software 'ANSYS' is employed for this study. The sphere and flat contact model is considered as a flattening model, the stress and strain for different materials are estimated. The simulation of wheel-rail contact model is also performed and the results are compared with the flattening model. The comparative study has also been extended for finding out the mean contact pressure for different materials the E/Y values between 150 and 660. The results show that the elastic-plastic contact analysis for materials up to E/Y=296.6 is depend on the nature of material properties and also for this material the mean contact pressure to yield strength reaches 2.65.

• Journal of Information Processing Systems
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• v.18 no.3
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• pp.359-373
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• 2022

The new crown pneumonia (COVID-19) has become a global epidemic. The disease has spread to most countries and poses a challenge to the healthcare system. Contact tracing technology is an effective way for public health to deal with diseases. Many experts have studied traditional contact tracing and developed digital contact tracking. In order to better understand the field of contact tracking, it is necessary to analyze the development of contact tracking in the field of computer science by bibliometrics. The purpose of this research is to use literature statistics and topic analysis to characterize the research literature of contact tracking in the field of computer science, to gain an in-depth understanding of the literature development status of contact tracking and the trend of hot topics over the past decade. In order to achieve the aforementioned goals, we conducted a bibliometric study in this paper. The study uses data collected from the Scopus database. Which contains more than 10,000 articles, including more than 2,000 in the field of computer science. For popular trends, we use VOSviewer for visual analysis. The number of contact tracking documents published annually in the computer field is increasing. At present, there are 200 to 300 papers published in the field of computer science each year, and the number of uncited papers is relatively small. Through the visual analysis of the paper, we found that the hot topic of contact tracking has changed from the past "mathematical model," "biological model," and "algorithm" to the current "digital contact tracking," "privacy," and "mobile application" and other topics. Contact tracking is currently a hot research topic. By selecting the most cited papers, we can display high-quality literature in contact tracking and characterize the development trend of the entire field through topic analysis. This is useful for students and researchers new to field of contact tracking ai well as for presenting our results to other subjects. Especially when comprehensive research cannot be conducted due to time constraints or lack of precise research questions, our research analysis can provide value for it.

• Journal of the Korean Dietetic Association
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• v.21 no.1
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• pp.72-82
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• 2015

The purpose of this study was to provide preliminary data for competitive dominance in an institutional foodservice environment. Data were collected from 85 experts and practitioners on customer-oriented service contact elements and contact fields in the foodservice industry. PASW Statistics ver.18 and MS Excel were used for data analysis. From the pilot study, 67 service contact-elements were derived. Contribution rate analysis and frequency analysis in each contact field were performed in order to categorize four factors, including environment-oriented contact, product-oriented contact, service-oriented contact, and image-oriented contact fields. Thirty three contact elements were derived, and environment-oriented contact consisted of eight contact-elements (cleanliness of restaurant/kitchen, etc.), product-oriented contact consisted of twelve contact-elements (food taste, etc.), service-oriented contact consisted of seven contact-elements (service quality, etc.), and image-oriented contact consisted of six contact-elements (image/reputation, etc.). The results of study will be useful to develop an effective marketing program for competitive dominance in an competitive foodservice industry environment.

• Tribology and Lubricants
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• v.28 no.6
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• pp.297-302
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• 2012

We conducted 3D elastic contact analysis of a sharkskin surface pattern for the characteristic assessment of biomimetic shark skin structure pattern for engineering applications. Rough sharkskin surfaces of similar size with real shark skin scales are generated numerically. Under the assumption of the contact of a plate on the generated sharkskin surface, contact performances such as contact pressure, real contact area, and surface separation are evaluated.

• Tribology and Lubricants
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• v.36 no.5
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• pp.262-266
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• 2020

Herein, we present a numerical investigation of wear analysis of sliding systems with a constant speed subjected to Archard's wear law. For this investigation, we compared two methods: eigen-wear analysis and adaptive meshing technique. The eigen-wear analysis is advantageous to predict the evolution of contact pressure due to wear using the initial contact pressure and contact stiffness. The adaptive meshing technique in finite element analysis is employed to obtain transient wear behavior, which needs significant computational resources. From the eigen-wear analysis, we can determine the appropriate element size required for finite element analysis and the time increment required for wear evolution by a dimensionless variable above a certain value. Since the prediction of wear depends on the maximum contact pressure, the finite element model should have a reasonable representation of the maximum contact pressure. The maximum contact pressure and wear amount according to this dimensionless variable shows that the number of fine meshes in the contact area contributes more to the accuracy of the wear analysis, and the time increment is less sensitive when the number of contact nodes is significantly larger. The results derived from a two-dimensional wear model can be applied to a three-dimensional wear model.

• Transactions of Materials Processing
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• v.15 no.3 s.84
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• pp.183-188
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• 2006

Heat transfer coefficients have great influence on finite element analysis results in elevated temperature forging processes. Experimentally calculated contact heat transfer coefficient is not suitable for one-time finite element analysis because analyzed temperature will be appeared to be too low. To get contact heat transfer coefficient for one-time finite element analysis, tool temperature in operation was measured with thermocouple and repeated finite element analysis was performed with experimentally calculated contact and cooling heat transfer coefficient. Surface temperature of active tool was obtained comparing measurement and analysis results. Contact heat transfer coefficient for one-time finite element analysis was achieved analyzing surface temperature between repeated finite element analysis and one-time finite element analysis results.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.5
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• pp.478-484
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• 2014

Ultrasonic atomic force microscopy(Ultrasonic-AFM) can be used to obtain images of the elastic properties of a subsurface and to evaluate the elastic properties by measuring the contact resonance frequency. When a tip is in contact with the sample, it is necessary to understand the cantilever behavior and the tip-sample interaction for the quantitative and reliable analysis. Therefore, precise analysis models that can accurately simulate the tip-sample contact are required; these can serve as good references for predicting the contact resonance frequency. In this study, modal analyses of the first four modes were performed to calculate the contact resonance frequency by using a spring model, and the deformed shapes of the cantilever were visualized at each mode. We presented the contact characteristics of the cantilever with a variety of contact conditions by applying the contact area, contact material thickness, and material properties as the parameters for the FEM analysis.