• Proceedings of the KSR Conference
• /
• 2009.05b
• /
• pp.447-453
• /
• 2009

The interior noise of the High Speed Train(HST) is analyzed by applying the statistical energy analysis (SEA) method. The interior of each vehicle is divided lengthwise into nine cavities. Since the rolling noise and aerodynamics noise are expected to be dominant noise sources, they are treated as the noise sources in the model. To further simplify the model, curtains and seats are excluded. The simulation runs involving one-car, three-car and five-car trains are conducted. The maximum predicted noise level is 98.4dB. The results also show that the predicted noise levels are within 0.23% of each other. The results imply that it is not necessary to estimate the interior noise of the train by constructing multiple-car train models. The noise estimate based on just one-car train can be optimal with respect to the computational effort and modeling time.

• Proceedings of the KSR Conference
• /
• 2008.11b
• /
• pp.1988-1998
• /
• 2008

Performed was a survey to find the level of interest on passenger services using IT and smart sensor technology in connection with High Speed Train development in Korea. The survey respondents were sampled from the KTX passengers, KTX crews, Korail employees, IT or sensor experts, and rolling stock experts. The results of the survey were categorized as importance, urgency/necessity, importance vs urgency/necessity, improvement measure, preferable activities based on the trip length, and inconveniencies. By analyzing the results, service items that can be implemented to the High Speed Train were recognized. The results showed that a passenger tends to expect to have his/her comfort and convenience, an attendant safety and serviceability, a Korail employee information provision and serviceability, an IT/sensor expert technological implementation done, and a rolling stock expert implementation done in practical level.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.22 no.12
• /
• pp.1227-1236
• /
• 2012

The low speed machinery faults are usually caused by the bearing failure of the rolling elements. As the life time of the bearing is limited, the condition monitoring of bearing is very important to maintain the continuous operation without failures. A few monitoring techniques using time domain, frequency domain and fuzzy neural network vibration analysis are introduced to detect and diagnose the faults of the low speed machinery. This paper presents a method of fault detection for the rolling element bearing in the low speed machinery using the Wiener filtering and shock pulse counting techniques. Wiener filter is used for noise cancellation and it clearly makes the shock pulse emerge from the time signal with the high level of noise. The shock pulse counting is used to determine the various faults obviously from the shock signal with transient pulses not related with the bearing fault. Machine fault simulator is used for the experimental measurement in order to verify this technique is the powerful tool for the low speed machine compared with the frequency analysis. The test results show that the method proposed is very effective parameter even for the signal with high contaminated noise, speed variation and very low energy. The presented method shows the optimal tool for the condition monitoring purpose to detect the various bearing fault with high accuracy.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.12 no.9
• /
• pp.668-673
• /
• 2002

The sources of wayside noise for the high -speed train are the aerodynamic noise, rolling noise and power unit noise. We should know the major source to control noise radiated from train. In this paper, we present the test results on the wayside noise and the vibration of the rail/sleeper during the passing of Korean Train Express (KTX). It turns out that the major noise sources for KTX are the rolling noise and power unit noise at 300 km/h. Generally, the noise attenuation with distance is independent of train speed. However, the test results show that in the near field the noise levels decrease by about 5~6 ㏈(A) per doubling of distance at speed in the range of 50~120 km/h and about 3~4 ㏈(A)/d.d at 300 km/h.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.11a
• /
• pp.424-426
• /
• 2008

A parametric study was carried out to find the fuel lubrication performance of high speed small rolling element bearings. Both MIL-PRF-7808 turbine oil and JP-8 aircraft fuel were used as the lubricant to compare the operational characteristics. 17 mm inner diameter deep groove ball bearing and 20 mm cylindrical roller bearing were used. A high speed bearing test rig was developed and the testing was done with varying applied load, cooling air temperature, lubricant flow rate, and speed. Fuel caused more cage wear than oil for ball bearing with increasing axial load and rotational speed. The bearing temperature using fuel was lower than that using oil, and this seems to be the result of the high cooling capacity of fuel. According to various tests, the fuel lubrication is applicable for the lubrication on the main shaft bearings of expendable small gas turbines.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.2286-2291
• /
• 2011

Technology on the rolling stock is very composition and system engineering. We have to consider to many parameters on the rolling stock design. High speed train is interface between rolling stock and infra system of rail, signal, communication etc. For many years testing operation has experienced substantial growth based on various advanced new technology. Recently some problems was clearly stated on effective management, practical use and testing operation of the the rolling stock on the technology change. This paper presents some results of the study on necessary requirements of the operation testing for rolling stock technology change. We propose a general plan to suggest the operation testing and the parameters of the rolling stock on the technology change in the text.

• Tribology and Lubricants
• /
• v.16 no.6
• /
• pp.477-483
• /
• 2000

Rolling contact fatigue (RCF) tests were performed for two kinds of commercial silicon nitride balls using 4-Ball rolling contact fatigue life tester under EHL condition (Λ=8.9) and boundary lubrication condition (Λ=0.2). All the test balls were finished up to the dimensional accuracy of Grade 5 defined in KS B 2001 (Steel Balls for Ball Bearings) with a size of 8.731 mm. RCF tests were then conducted under the initial theoretical maximum contact stress 6.63 GPa and the spindle speed 10,000 rpm. All the test balls were not failed until 3.75 $\times$ 107 contact cycles and wear tracks of test balls were not conspicuous under EHL condition (Λ= 8.9). In the operations of low lambda regime (Λ= 0.2), all the test balls were surface damaged and high rolling wear resistance was achievable in fully densified using MgO 1 wt% and HIPed balls. Rolling wear of silicon nitride balls under boundary lubrication condition depend mainly on grain size and intergranular phase content of silicon nitride balls.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.06a
• /
• pp.979-980
• /
• 2008

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.4
• /
• pp.454-460
• /
• 2016

Unlike conventional visible light communications (VLC) adopting photo detectors (PD), optical camera communications (OCC) employs cameras in detecting the transmitted data. Especially, the data rate of OCC can be enhanced by using the principle of rolling-shutter, which is the operating scheme of a CMOS image sensor. In this study, we consider a novel OCC system for high-speed real time video processing to transmit high speed data from LED and to acquire image utilizing rolling-shutter effect of CMOS image sensor. Also, we demonstrate the improved performance of proposed system using a test-bed.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.158-166
• /
• 2007

After constructing the high-speed railroad, KORAIL acquired advanced maintenance techniques about Rolling-stocks. Also RCM theory is applied to maintenance field like as inspection period and method. In the meantime, the development of the maintenance methode for Rolling-stock is slow when it compares to the components and system technology. For this reason KORAIL tries to build the optimal maintenance system which can lead the Rolling-stock maintenance technique. The existing vehicle except High Speed train KTX are separated to electric motor car, electric locomotive, diesel locomotive, diesel car, passenger car and freight car. The inspection period and methode for existing vehicles which mentioned above will be examined and the optimal Rolling-stock maintenance technique will be applied.