• Journal of the Korean Society for Railway
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• v.3 no.2
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• pp.51-61
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• 2000

In this study, field measurements of vibration on the structures supporting railroad track were performed. The vibration data obtained were analyzed to find out any correlation between its magnitude and several factors such as type of bridges, distance from the track, type of train, frequency characteristics, etc. As a result, the magnitude of vibration turned out to be the highest in the steel bridge, the concrete bridge and steel-concrete combined bridge were the next in descending order. It was also found that the dynamic characteristics of ground were the most important factors among several affecting vibration near by the railroad track. And the empirical ground vibration estimation equation for estimating ground vibration was developed. The proposed equation with respect to distances from the railroad could be easily used for the estimation of ground vibration at the residential areas nearby the track.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.671-679
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• 2010

The construction of concrete track for the first time in Korea gives lots of meanings to civil engineering in various aspects. Settlement level needs to be kept minimal for the safety of the track. Concrete track has different structural characteristics comparing to conventional ballast track, so load distribution in concrete track is also different. Since it is the first time to build concrete track, there are very few experience and data available on the subject. Therefore it is important to evaluate how much load is transferred to the ground due to the running vehicle in concrete track and to determine the optimal thickness of layers. In this research, 9 individual earth pressure cells were installed at OOOk930 site in 2nd stage of Kyungbu high speed railway during under construction. The in-situ pressure data were measured at each layers during pump-car and locomotive were moving on the high speed railway surface.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.9
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• pp.117-122
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• 1999

Track rubber parts has heat built-up as long as dynamic loading is applied from running tracked vehicles. Durability is required for rubber part to sustain the heat accumulation and heat exchange between rubber-metal assembly and environmental air and ground. For this research, the track assembly was divided into four parts i.e., bottom track shoe, upper track pad, pin busing and metal structure. Three rubber parts and metal structure were modelled and analyzed with MARC package program to obtain time-temperature data which was induced form mechanical work of tracked vehicles. heat accumulation data was obtained from special experiments under the room temperature of 25$^{\circ}C\;and\;35^{\circ}C$ to simulate the actual environmental conditions. From this research, it is cleared that the environmental temperature does not affect to the heat accumulation speed in rubber parts. Also, the heat built-up mechanism was clarified from the thermo-mechanical work based on numerical analysis and experiments.

• Wind and Structures
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• v.35 no.5
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• pp.309-322
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• 2022

Due to the complex terrain around high-speed railways, the windbreaks were established along different landforms, resulting in irregular windbreak transition regions between different subgrade infrastructures (flat ground, cutting, embankment, etc). In this paper, the effect of a windbreak transition on the wind flow around railways subjected to crosswinds was studied. Wind tunnel testing was conducted to study the wind speed change around a windbreak transition on flat ground with a uniform wind speed inflow, and the collected data were used to validate a numerical simulation based on a detached eddy simulation method. The validated numerical method was then used to investigate the effect of the windbreak transition from the flat ground to cutting (the "cutting" is a railway subgrade type formed by digging down from the original ground) for three different wind incidence angles of 90°, 75°, and 105°. The deterioration mechanism of the flow fields and the reasons behind the occurrence of the peak wind velocities were explained in detail. The results showed that for the windbreak transition on flat ground, the impact was small. For the transition from the flat ground to the cutting, the influence was relatively large. The significant increase in the wind speeds was due to the right-angle structure of the windbreak transition, which resulted in sudden changes of the wind velocity as well as the direction. In addition, the height mismatch in the transition region worsened the protective effect of a typical windbreak.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.365-370
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• 2007

Foundation settlements(settlements at the embankment surface and ground) has been evaluating to satisfy the strict allowable residual settlement level from the start of the construction of Gyungbu high speed railway. This is because both embankment and ground settlement could be important to minimize the residual settlement after the construction of concrete track. Ground settlement is caused by the increase of effective stress resulting from embankment. The causes of embankment settlement could be come from different sources, for example, the increase of effective stress, rainfall, creep behaviors. Based on the field measured data, this paper analysed the settlement of ground and embankment settlement. The biggest settlement at the embankment surface was 9.7mm during 246days at the STA 000k922.5. The calculated settlement of embankment itself was 8.6mm at the same places. These results conclude that the compressive settlement of embankment could not negligible.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.10
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• pp.44-51
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• 2012

The purpose of this study is development of the diagnosis system to preventative maintenance in the on-board measuring systems for in-cab electric inspection systems of high speed railway. The on-board measuring systems can inspect precisely whether ground signal system operate stably. In this paper, we recognize characteristics of the track circuits and confirm whether the wave of current matches the on-board measuring data through the electric modeling method for high speed railway. it is necessary to develop GUI visual programs that can simulate abnormalities of the on-board measuring data in many ways, and the visual program is designed to diagnosis in the case of track circuit equipment's function decreased in advance.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.203-210
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• 2000

Recently, environmental vibration by train operation has been getting such an attention that the ISO puts it into the environmental vibration regulation. However, the reasonable and efficient countermeasures against such a kind of vibration is not well established, especially in residential areas near the railroad. Therefore, it is very important to estimate the ground vibration induced by the train operation for the design and construction of track supporting structures as well as structures near the track. In this study a model estimating dynamic load on track due to train operation and analysis technique of propagation of ground vibration were developed. Futhermore, the estimated vibration from this model was compared with the actual measurement data in the field and found to be reasonably acceptable.

• Korean Journal of Applied Biomechanics
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• v.17 no.3
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• pp.69-80
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• 2007

The purpose of this study was to investigate the difference of ground reaction forces of swimming athletes during their starting motion and to find out the most effective starting motions which were used in swimming athletes. The subjects were 9 male and 8 female high school swimming athletes who were athletic career over 7 years and used three starting motions in competition. The ground reaction forces were measured from each athletes performing three starting motion each of the open grap starting motion, closed grap starting motion and track starting motion. For the measurement, the force platform of AMTI company was utilized, and the analysis on measured ground reaction forces were used of Biosoft(Ver. 1.0). The items measured were stance time, Fz max deceleration force and Fz max deceleration force time, Fz mid stance force and Fz mid stance force time, Fz max acceleration force and Fz max acceleration force time, Torque maximum and Torque maximum time, Torque average, Excursion along Y axis of center of pressure of foot, Excursion along X axis of center of pressure of foot, Length of center of pressure of foot, Average velocity of center of pressure of foot. The data measured by the closed grap starting motion, open grap starting motion and track starting motion were analyzed by one-way repeated ANOVA. The results were as follows ; 1. The Fz max deceleration force time, Fz mid stance force, Fz max acceleration force, Torque maximum and Torque maximum time, Excursion along Y axis of center of pressure of foot, Average velocity of center of pressure of foot were significantly fast and large in the closed grap starting motion then open grap starting motion and track starting motion. 2. The Excursion along Y axis of center of pressure of foot was significantly long in the closed grap starting motion then open grap starting motion and track starting motion.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.6
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• pp.572-580
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• 2015

RF skin tracking of instrumentation RADAR cannot acquire stable track data, because of effect of multipath interference especially elevation direction. In this paper, low altitude target tracking method using laser tracking system is suggested to overcome this restriction. The effect of multipath can be reduced by increasing angle resolution with laser characteristics of very short pulse and narrow beamwidth. RF skin track, beacon track and laser track data for the integrated calibration target on the ground and target ship on the sea are gathered. And they are compared and analyzed to confirm the performance of laser tracking system. As a result, it shows that the suggested laser track method has better performance than RF skin track under multipath conditions.

• Journal of Aerospace System Engineering
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• v.6 no.4
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• pp.34-39
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• 2012

CubeSats classified as pico-class satellite require a ground station to track the satellite, transmit a command, and receive an on-orbit data such as SOH (State-of-Health) and mission data according to the operation plan. For this, ground station system has to be properly designed to perform a communication to with the satellite with enough up- and down-link budgets. In this study, a conceptual design of the ground station has been performed for the CubeSat named as STEP Cube Lab. (Cube Laboratory for Space Technology Experimental Project). The paper includes a ground station hardware interface design, link budget analysis and a ground station software realization. In addition, the operation plan of the ground station has been established considering the STEP Cube Lab. mission requirements.