• Proceedings of the KSR Conference
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• 2003.10b
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• pp.591-595
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• 2003

Field measurements were conducted to analysis lateral dynamic characteristics of existing steel plate girder railway bridges without ballast. Three bridges which have 9m, 12m, 18m span length in Kyoung-Bu Line were selected for test. According to the each bridge, dynamic lateral deflections and accelerations were measured. From the present study, it was observed that dynamic lateral amplification phenomena caused by a fluctuation of lateral force were occurred under the current running circumstances. Lateral deflections were occurred below than that specified in Korean railway bridge specification, but lateral accelerations is a match for vertical accelerations. From now on, it is in need a plan to reduce lateral accelerations for the conventional railway Line speed up.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.596-601
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• 2003

After the development of practical technology for tilting system, tilting trains are operated on conventional lines of KORAIL. As the running speed of trains is increased, it is very important to investigate the dynamic characteristics of plate girder bridges with direct track fixation. Therefore, this paper reviews the dynamic interactions between tilting train and welded plate girder bridges designed by L-22, a standard load type of KORAIL. The span lengths of plate girder analyzed here are 6.6m, 9.7m, 12.9m, 16.0m, 19.2m, 22.3m, 25.4m and 31.1m. Using 2-D dynamic analysis, the critical velocity of tilting train, vertical deflection ratios of plate girder and maximum accelerations of car body are calculated. And the analytical results are compared with those of design criteria.

• Journal of the Korean Society for Railway
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• v.10 no.2 s.39
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• pp.243-250
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• 2007

In general the Maglev vehicle is run over the elevated track called guideway. Since the guideway is elevated, the flexibility of the guideway has an effect on the dynamic responses of a vehicle such as its stability and ride quality. To improve the running performance of the Maglev vehicle and design a cost effective guideway using the dynamic analysis, the dynamic analysis of the system requires the coupling model of the Maglev vehicle and guideway. A coupling model based on multibody dynamics is proposed and programmed. With the program, the UTM01, a low speed Maglev vehicle, is analyzed and discussed.

• Wind and Structures
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• v.20 no.2
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• pp.117-142
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• 2015

The performance of bridges under strong wind and traffic is of great importance to set the traveling speed limit or to make operational decisions for severe weather, such as controlling traffic or even closing the bridge. Meanwhile, the vehicle's safety is highly concerned when it is running on bridges or highways under strong wind. During the past two decades, researchers have made significant contributions to the simulation of the wind-vehicle-bridge system and their interactive effects. This paper aims to provide a comprehensive review of the overall performance of the bridge and traffic system under strong wind, including bridge structures and vehicles, and the associated mitigation efforts.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.77.2-77.2
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• 2014

Questions of how our Milky Way evolves through the interaction with its environment have been constantly raised. One particularly interesting question is how the metallicity would change as our Milky Way goes through collision with HVCs. Because of the possibility of HVCs providing fuel for star formation in the Galactic disk, we simulate the collision between HVCs and the Galactic disk. More specifically, we trace how the Galactic metallicity changes throughout the process of HVCs colliding with our Milky Way based upon a specific scenario that HVCs are primordial gas left-overs from an ancient galaxy formation. Such mixing between metal-rich gas (disk) and metal-poor HVC can be traced by running numerical simulations with the FLASH code due to its capability of tracking down the abundance change of a specific element such as carbon at each time step of the hydrodynamic evolution. As for now, we give how this mixing depends on model parameters that we choose such as collision speed, initial metallicities, temperature and so on.

• 전기의세계
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• v.24 no.1
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• pp.55-62
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• 1975

A single-phase induction motor with it's stator winding splitted into two series windings, of which the terminals of one winding is switched pulsationally by a thyristor type ON-OFF device so that the motor may operate as a pulsational shaded-pole motor, can modulate current waveforms of it's two series windings. In view of current waveform modulation method, a single-phase single-winding motor operates as a two-phase induction motor with asymmetrical axis windings where the starting torque can be obtained effectively without an auxiliary capacitor attached and it's running speed controlled by shifting phase between current waveforms differently. Equivalent circuit for analysis is modified from a double revolving field equivalent circuit of a single-phase induction motor with asymmetrical windings whose angle is 45.deg.C elet. degrees. Analysis and test results show that ON-OFF action of the pulsational shaded-pole winding has the same effect of a series capacitor, and then at heavy loads this motor operates with a small amonut of the input current than that having the fixed shaded-pole winding.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.776-778
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• 1999

In this paper, identifier for thermal storage system using multi-layer feedforward neural network (MFNN) is designed. It is very difficult to control thermal storage system, since thermal storage system is nonlinear and its time constant is very large. Thus, in the MFNN, delta-bar-delta algorithm for high running speed and 2-bit status input are used. Also hardware using microprocessor for identifier is developed. The experimental results indicate that the proposed method can predict temperature more accurately.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.1159-1160
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• 2008

For safety railway vehicle movement, analysis and recoding of railway vehicle speed and driving information has written by law. nowadays, base in europe, these system is spread of various advanced country. In this paper, We implement an event recorder which record the driving and breaking information of running railway vehicle. For the event recorder, We designed the data structures with data analysis tools and a protocol between Event recorder and data analysis tool. The verification of Analysis tool was tested by to made data by Event Recorder's emulator and information of real railway driving recording.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.214-215
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• 2005

Naval equipments are installed and used for naval vessel with different environmental conditions comparing to the commercial vessel, for example, high engine power per ship displacement size, severe vibration and shock due to high running speed and explosion from naval gun's bombardment and underwater weapons. Therefore, those equipments must be installed on shipboard with small spaces, high ambient temperature around engine room and which are required be fabricated with high resistances of vibration, shock and heat resources. But in case of commercial vessel, the performances of their recent equipments naval have been improved continuously due to the technology development of domestic shipbuilding and shipboard equipment industries, together with the related fundamental industries i.e, metal, steel and electronic industries, to an international level since 1970. With these results, it became possible to unify the specifications of shipboard equipments for the commercial and military vessels(Dual-Use). In this study, vibration and shock test standards for the commercial and military vessels will be compared and reviewed technically.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.46-52
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• 2001

One of the important technical issues is how to decrease thermal expansion of ballscrew in proportion to the increase of machining speed. when measuring force of stretch of ballscrew, since not only actual expansion and the value of bending have to be considered, it's impossible to definite the exact value of expansion. In addition, support bearings of ballscrew gain considerable force in axial direction. It also generates thermal expansion on the ballscrew, and deteriorates the bearings. In conclusion, it's impossible to give the pretension enough to absorb the all elongation due to thermal expansion generated during machine running. If gave, bed, column and saddle are all bent to change machine accuracy, and the support bearings of ballscrew are damaged. The purpose of this paper is to study the pretension of support bearing of ballscrew in machine tool.