• Smart Structures and Systems
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• v.18 no.5
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• pp.1063-1085
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• 2016

Taking advantage of the high sensitivity and long-distance detection capability of acoustic emission (AE) technique, this paper focuses on the crack detection in rail head, which is one of the most vulnerable parts of rail track. The AE source location and noise cancellation were studied on the basis of practical rail profile, material and operational noise. In order to simulate the actual AE events of rail head cracks, field tests were carried out to acquire the AE waves induced by pencil lead break (PLB) and operational noise of the railway system. Wavelet transform (WT) was first utilized to investigate the time-frequency characteristics and dispersion phenomena of AE waves. Here, the optimal mother wavelet was selected by minimizing the Shannon entropy of wavelet coefficients. Regarding the obvious dispersion of AE waves propagating along the rail head and the high operational noise, the wavelet transform-based modal analysis location (WTMAL) method was then proposed to locate the AE sources (i.e. simulated cracks) respectively for the PLB-induced AE signals with and without operational noise. For those AE signals inundated with operational noise, the Hilbert transform (HT)-based noise cancellation method was employed to improve the signal-to-noise ratio (SNR). Finally, the experimental results demonstrated that the proposed crack detection strategy could locate PLB-simulated AE sources effectively in the rail head even at high operational noise level, highlighting its potential for field application.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.229-232
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• 1997

In this paper, we describe about the field test of polymeric long rod insulator for rail way. For the test, insulators were mounted at the feeder line system at Kuro base station and were exposed to environmental, electric, and mechanical stress. During the test service, the leakage current was been monitoring and stored the data by the leakage current measuring system that was specially constructed. After about 6 months, diagnostic tests for evaluation of the installed insulators were conducted. The test results developed that the developed polymeric insulator is valid to use for rail way.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.69-72
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• 2000

In this paper, the electrical properties due to epoxy resin used in transformer of rail road signal are studied. The specimen of epoxy resin was hardened as each 3[h], 4[h], 5[h] in this experiment. In order to measure the conductivity properties, the highmegohm meter is used at temperature 25 to 140[$^{\circ}C$] and applying voltage 100 to 1000[V]. As a result of this experiment, we confirmed that 3[h] specimen is better than the others.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.202-206
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• 2006

Although the urban rail vehicle is exposed to the fire disaster, most country, except only a few advanced country, is insufficient to take a measure against the fire accident. Safety regulation modification, fire safety standard of the materials. and each material's fire resistance of the rail vehicle have been upgraded until the Daegu fire disaster in Korea. For that reason, In this study, current techniques of fire safety evaluation are analyzed and fire safety degrees of rail vehicles are compared with the change of interiors which is met to the fire safety standard of urban rail vehicle.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.7
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• pp.541-549
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• 2016

Rolling contact fatigue and wear on rails are inevitable in railway operations due to excessive wheel-rail contact stress. The wear is influenced by vehicle speed, contact pressure, environmental conditions, and many other factors. Speeding on a curved track causes many problems such as wear on the gauge of the rail and rolling contact fatigue. Managing environmental conditions can reduce problems on the wheel and rail interface. In this study, the wear characteristics of wheel and rail materials were investigated by twin-disc testing using various parameters. The results of the wear test indicated that the wear rate under dry conditions was larger than that under wet conditions. We found that contact fatigue damage occurred on the rail in dry conditions, however, the surface of the specimen under water remained smooth. Also, the friction coefficient in dry conditions was larger than in wet conditions.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.332-336
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• 2008

A pulsation damper is usually mounted on the fuel rail to diminish undesirable noise in the vehicle cabin room. However, pulsation dampers are quite expensive. Therefore, several studies have focused on reducing fuel pressure pulsations by increasing the self-damping characteristics of the fuel rail. This paper is a basic study in the development of a fuel rail that can reduce pulsations via a self-damping effect. In this study, the pressure pulsation characteristics were of investigated with respect to the aspect ratio of the cross section, wall thickness, and fuel rail material through oil hammer simulations. An oil hammer simulation was performed in advance to simulate the pressure pulsations at the resonant speed, which is a time-saving way. The pressure pulsation peak of fuel rail was observed to rise as the injection period increases. Increase of the aspect ratio and decrease of the wall thickness can reduce the pressure pulsation efficiently.

• Journal of Industrial Technology
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• v.21 no.B
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• pp.287-294
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• 2001

This study is aimed to evaluate the springback characteristics of automotive steel sheets through the S-rail forming test and to find the process condition under which springback can be reduced. Die set for the S-rail test has been made according to the dimension of the NUMISHEET '96 benchmark model. Experiment and finite element analysis have been performed on two kinds of automotive steel sheets: mild steel, SPCEN and high strength steel, SPRC. The test results show that the amount of springback is larger on the high strength steel SPRC than on the mild steel SPCEN, and decreases with increasing blank holding force as the case of material flow. And the reduction of friction has the effect of lowering the blank holding force in view of punch force and material flow. It is shown that the strain distribution over the whole specimen and along the specified sections calculated from the finite element analysis coincides with the measured data except local differences.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.2
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• pp.125-130
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• 2016

In this paper, various heat dissipation designs for a rail anchoring failure detection module were investigated by a thermal flow analysis. For the detection module with the heat dissipation design on the overall housing surface, an average temperature inside the module was lowered by $25^{\circ}C$ when compared to no heat dissipation design. In addition, an internal heat-flow blocking layer and an heat conduction layer inserted between the LED module and housing case were effective in reducing the temperature in the rail anchoring failure detection, which has a limited space for installation and little air flow. Especially, the temperature near LED module decreased below $55^{\circ}C$ when the optimal heat dissipation design was applied.

• Journal of the Korea Safety Management & Science
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• v.12 no.1
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• pp.35-42
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• 2010

Due to the industrialization and urbanization, the transport of hazardous materials increases, which rises possibilities in occurring prospective accidents in terms of hazardous material transport as well. This study applied the model developed from the previous research to analyze the scale of damage areas from the accidents related to hazardous material accidents, as well as suggested a method to measure automatically the scale of accident including casualties and environmental damage based on the guideline which suggests the quantities of hazardous materials exposed from an accident and was defined in the study of standardization for hazardous material classification. A buffering analysis technique of Geographic Information System (GIS) was applied for that. To apply the model which evaluates the scale of population and exposure to environment on each link, rail network, zones, rail accident data, rail freight trips, and locations of rivers etc were complied as a database for GIS analysis. In conclusion, a method to measure damage areas by the types of hazardous materials was introduced using a Clip and a Special Join technique for overlay analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.5709-5715
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• 2012

Injection molding product is commonly used for reducing the weight of automotive vehicle, and door regulator guide rail with plastic material is also made by injection molding process. In order to improve the injection molding performance of plastic regulator guide rail, optimal molding condition is suggested by numerical simulation and DOE after obtaining the sensitivity of parameters for regulator rail manufacturing on warpage and fill time. Furthermore, multi direct gate method and optimal cooling circuit are introduced to get the uniform temperature distribution and better cooling efficiency in molding product. The effect of the proposed design on the injection molding performance is verified by the test of prototype of plastic regulator guide rail.