• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1583-1584
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• 2013

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.381-382
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• 2007

• International Journal of Highway Engineering
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• v.8 no.3 s.29
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• pp.21-28
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• 2006

Field or laboratory wheel tracking tests have been employed for the evaluation of the rutting potential of asphalt paving mixtures. Compared to field tests, laboratory wheel tracking tests are much less expensive and more manageable for most road projects. However, most test laboratories are not equipped to perform such tests because there does not exist any standard test procedure, and the required equipment is rather expensive. Futhermore, the size of test specimens and the relatively large quantity of test mixture required present difficulties for laboratory specimen mixing and compaction. This paper describes a project conducted to study the feasibility of replacing wheel tracking testsby a repeated-load creep test for rutting potential evaluation. Comparisons were made between the results of the two tests for different test temperatures, loading speeds and applied pressures. Three types of asphalt mixtures were studied in the test program. Favorable conclusions concerning the use of the repeated-load test for rutting potential evaluation were drawn based on the findings of the experimental test results. The correlation between the two types of tests was found to be good for all threeasphalt mixtures. Adopting the repeated-load creep test would lead to cost savings since it employs standard test equipment already available in most laboratories. It would also result in substantial time savings due to the much smaller quantity of mix needed, and the ease in specimen preparation.

• Journal of Korean Academy of Nursing
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• v.45 no.3
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• pp.459-468
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• 2015

Purpose: The purpose of this study was to investigate the effects of Wheel of Wellness counseling on wellness lifestyle, depression, and health-related quality of life in community dwelling elderly people. Methods: A parallel, randomized controlled, open label, trial was conducted. Ninety-three elderly people in a senior welfare center were randomly assigned to two groups: 1) A Wheel of Wellness counseling intervention group (n=49) and 2) a no-treatment control group (n=44). Wheel of Wellness counseling consisted of structured, individual counseling based on the Wheel of Wellness model and provided once a week for four weeks. Wellness lifestyle, depression, and health-related quality of life were assessed pre-and post-test in both groups. Results: Data from 89 participants were analyzed. For participants in the experimental group, there was a significant improvement on all of the wellness-lifestyle subtasks except realistic beliefs. Perceived wellness and depression significantly improved after the in the experimental group (n=43) compared to the control group (n=46) from pre- to post-test in the areas of sense of control (p =.033), nutrition (p =.017), exercise (p =.039), self-care (p <.001), stress management (p =.017), work (p =.011), perceived wellness (p =.019), and depression (p =.031). One participant in the intervention group discontinued the intervention due to hospitalization and three in the control group discontinued the sessions. Conclusions: Wheel of Wellness counseling was beneficial in enhancing wellness for the community-dwelling elderly people. Research into long-term effects of the intervention and health outcomes is recommended.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1011-1016
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• 2010

The noise emitted during train operation is generated with various reasons. It is known that the major noise generation is classified according to the ranges of train speed; that is, engine noise at lower speed range, rolling noise at medium speed range, and air-borne noise at higher speed range. These noises are transmitted in combined form with the noises generated from track components and under-carriage, etc. The rolling noise as a major noise at medium speed range is caused by the vibration occurred at wheel/rail interface. The vibration occurred at wheel/rail interface is transmitted to wheel and rail, and this vibration is emitted from wheel and rail as a noise. The object of this study is to investigate the effect of wheel damper of low noise wheel. In this study theoretical and experimental analysis is performed by numerical model calculations and impact test.

• Smart Structures and Systems
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• v.23 no.4
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• pp.347-357
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• 2019

A new methodology for mitigation of the wheel squealing is proposed and investigated based on the dithering control. The idea can be applied in railway lines particularly in urban areas. The idea is clearly presented, and applied to a validated model. A full-scale model including the vehicle, curved track and wheel/rail contact is developed in the time domain to analyze the possibility and level of wheel squeal noise. Comparing the numerical results with a field test, the model is validated in different levels namely i) occurrence, ii) squealing frequency and iii) noise level. Two different approaches are proposed a) dithering of the wheel with piezoelectric patches and b) dithering of the rail with piezoelectric stacks. The noise level as well as the wheel responses is compared after applying the control strategy. A parametric study is carried out and effect of the dithering voltage and frequency on the squealing noise is investigated. It is found that both the strategies perform quite effectively within the saturating threshold of piezoelectric actuators.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.8
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• pp.35-41
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• 2010

White Etching Layer(WEL) is a phenomenon that occurs on the surface of rail due to wheel/rail interactions such as excessive braking and acceleration. Rolling Contact Fatigue(RCF) cracks on the surface of rail have been found to be associated with WEL. In this study, we have investigated RCF damages of white etching layer using twin disc testing and fatigue analysis. These tests consist of wheel flat tests and rolling contact fatigue tests. WEL has been simulated by wheel flat test. It has been founded that the WEL with a bright featureless contrast is formed on the surface of specimen by etching. Rolling contact fatigue test was conducted by using flat specimens with the WEL generated by the wheel flat test. It has been observed that two types of cracks occur within the specimen. The contact fatigue test was simulated in 2D elastic-plastic FE simulations. Based on loading cycles obtained from the finite element analysis, the fatigue life analysis according to the thickness variation of WEL was carried out. The longest fatigue life was observed from the thickness of 20um.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.5
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• pp.559-564
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• 2011

For the safety of railway, it should be evaluated for the running safety by measuring the derailment coefficient. Although railway has run the fixed and maintained rail, some of railway is derailed. This report shows the results that performed the static load test, main line running test on the basis of the derailment theory and experience. It is executed main line test into more than 90km/h for estimating the curving performance and running safety of depressed center flat car of 3-axle bogie. As the test results, could confirm the curving performance and running safety of depressed center fiat car of 3-axle bogie from the results of the wheel unloading, lateral force, derailment coefficient etc. Derailment coefficient was less than 0.6, and lateral force allowance limit and wheel load reduction ratio were enough safe.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.188-192
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• 2002

In this study, Curve dependent wheel flange lubricator with grease spray type is introduced and checked and estimated a point of view reducing wheel flange wear and noise in the curve. Advantage of curve dependent wheel flange lubricators with grease spray type is found on the basis of the result of field test applied to KNR No. 1 Line(reconstruction car).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.836-839
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• 2003

In this paper, we briefly introduce the test bench and test method of RWA micro-vibration. TAMAM RWA (Reaction Wheel Assembly) micro-vibration was measured on a KISTLER dynamic plate which can measure time signals of three orthogonal forces and torques simultaneously up to 400Hz, and test data was analyzed. Measured data were evaluated with respect to the wheel spin rate and the static/dynamic unbalances were estimated from the extracted first harmonic component. The estimated static and dynamic unbalances were 0.79gㆍcm and 17.4gㆍ$\textrm{cm}^2$ respectively. The resonance mode and two rocking modes were observed as a results of its frequency analysis. Several higher order harmonic components were observed, which comes from its rotor shape as well as the wheel bearing.