• Journal of the Korean Geophysical Society
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• v.3 no.4
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• pp.269-280
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• 2000

Rail vibration in city zone is becoming a serious environmental problem. In order to make a reduction plan for rail vibration, the research was conducted in which many experiments to measure actual rail vibration along the railroad through the central Deajeon area. A digital vibration level meter was used to measure rail vibration. Vibration levels of Z-axis were measured at every second for the duration of the train passing. The measuring station was placed at every 5m for the distance of 55m. A total of 353 different sets of vibration level were obtained. The signals were processed to get $L_{10}$ value and analyzed in terms of distance, train velocity, and number of trains. As a result, it has been found that rail vibration exceed the allowable vibraton limit of 60 dB, at the point of 25 m far from the railroad center, which is regulated by the las of vibration and noise. Train velocity was found to affect a little for vibration level within the zone. It was also found that a trench installed along a railroad could reduce vibration level up to approximately 10 percent. A model test was conducted to investigate the influence of the location and size of trench, on the transfer of vibration. A heavy steel ball was used to generate vibrations. On the basis obtained from this study, it could be concluded that the application of distance-attenuation and the installment of a trench along railroad could be applied as a reduction plan for rail vibration. Because limitions might exist to depend on the effect of distance attenuation, trenchs excavated along a railroad might be suggested as the most efficient solution to reduce railroad vibration.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.129-134
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• 2007

When constructing a high-speed railroad, the reduction of the distance between track centers and the width of track bed may bring about the effect of cost savings. When, however, considering the influence that the increase of wind pressure due to the change of the distance between track centers may have on the stability of train operation, extensive technical review and overall studies need to be performed before the distance between track centers is determined. Therefore, in this study, the impact that the increase in wind pressure due to the change of aerodynamic phenomena with the change of the distance between track centers may have on two trains passing by each other was predicted, and the stability of train operation was analyzed in order to review the distance between track centers suitable to Honam HSR trains. In this study, we estimated the aerodynamical effects by the results of the real train experiments.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.6
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• pp.345-352
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• 2018

It is inevitable to use the distinct element method in the analysis of structural dynamics for stacked stone pagoda system. However, the experimental verification of analytical results produced by the discrete element method is not sufficient yet, and the theory of distinct element method is not universal in Korea. This study introduces how to model the stacked stone pagoda system using the distinct element method, and draws some considerations in the seismic analysis procedures. First, the rocking mode and sliding mode are locally mixed in the seismic responses. Second, the vertical stiffness and the horizontal stiffness on the friction surface have the greatest influence on the seismic behavior. Third, the complete seismic analysis of stacked stone pagoda system requires a set of the horizontal, vertical, and rotational velocity time histories of the ground. However, earthquake data monitored in Korea are limited to acceleration and velocity signals in some areas.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.516-521
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• 2005

Recently the railway becomes principal transportation on account of the important role in mass transit and commute in urban area. However, rail noise and vibration raise a major problem for the residents living nearby railway track. At that point of view, the effective counterplan for the soundproofing and protection of vibration has to be considered in the process of railway design. Therefore, the reliable computation of load caused by running train on rail is very important to estimate vibration of structure adjacent to railway. In this study, Input identification is used for the calculation of load and vibration, induced by high speed train on rail. The influence of railroad noise and vibration on structure is evaluated using the 3-D Finite element method and the reliability of the evaluation is discussed comparing with the results of the field measurements.

• Journal of the Korean Society for Advanced Composite Structures
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• v.3 no.4
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• pp.17-26
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• 2012

This study presents a governing equations of bending behavior of anisotropic sandwich plates with multi-layered laminated composite faces. Based on zig-zag models for through thickness deformations, the shear deformation of composite faces is included. All edges of plate are assumed to be simply supported. Results of the bending analysis under lateral loads are presented for the influence of various lay up sequences of antisymmetric angle-ply laminated faces. The accuracy of the approach is ascertained by comparing solutions from the sandwich plates theory with composite faces to the laminated plates theory. Since the present analysis considers the bending stiffness of the core and also the transverse shear deformations of the laminated faces, the proposed method showed higher than that calculated according to the general laminated plates theory. The information presented might be useful to design sandwich plates structure with polymer matrix composite faces.

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.73-80
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• 1999

Belief revision involves integrating new information with the current belief. It is a ubiquitous human activity. A critical feature of belief revision lies in its sequential nature. Railroad system can be described as organic. Engine drivers take a great role in this system. Recently, Hogarth and Einhorn(1992) have Posited a belief-adjustment model for updating beliefs. Based on a sequential anchoring and adjustment strategy, the model is important fro decision makers. The sequential nature of information processing is affected by some task variables. This will be mainly explained in this paper. The purpose of this study is to examine the engine drivers' belief revision process and factors which influence on the belief revision process. The factors are the order and the experience. Thereby, this will contribute to the study of engine drivers' behavior. The result of this study is summarized as follows. The order effect due to the order of presentation of the evidence exist. The difference of belief revision is due to The experience level.

• Journal of IKEEE
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• v.15 no.2
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• pp.143-148
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• 2011

MOS (Metal-Oxide Semconductor) devices among the most sensistive of all semiconductors to radiation, in particular ionizing radiation, showing much change even after a relatively low dose. The necessity of a radiation dosimeter robust enough for the working environment has increased in the fields of aerospace, radio-therapy, atomic power plant facilities, and other places where radiation exists. The power MOSFET (Metal-Oxide Semiconductor Field-Effect Transistor) has been tested for use as a gamma radiation dosimeter by measuring the variation of threshold voltage based on the quantity of dose, and a maximum total dose of 30 krad exposed to a $^{60}Co$ ${\gamma}$-radiation source, which is sensitive to environment parameters such as temperature. The gate oxide structures give the main influence on the changes in the electrical characteristics affected by irradiation. The variation of threshold voltage on the operating temperature has caused errors, and needs calibration. These effects can be overcome by adjusting gate oxide thickness and implanting impurity at the surface of well region in MOSFET.

• International Journal of Railway
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• v.6 no.2
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• pp.59-63
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• 2013

The purpose of this paper was to evaluate the effectiveness of geogrid for conventional ballasted track and asphalt concrete underlayment track using PLAXIS finite element program. Geogrid element was modeled at various locations that include subballast/subgrade, subballast/ballast interfaces, middle of the ballast, and one-third depth of the ballast. The results revealed that the effectiveness of geogrid reinforcement appeared to be larger for ballasted track structure compared to asphalt concrete underlayment track. Particularly, in case of installing geogrid at one-third depth of ballast layer in a conventional ballasted track, the most effectiveness of geogrid reinforcement was achieved. The influence of geogrid axial stiffness on track substructure response was not clear to conclude. Further validations using a discrete element method along with experimental investigation are considered as a future study. The effect of asphalt concrete layer modulus was evaluated. The results exhibited that higher layer modulus seems to be effective in controlling displacement and strain of track substructure. However it also yields slightly higher stresses within track substructure. It infers that further validations are required to come up with optimum asphalt concrete mixture design to meet economical and functional criteria.

• Journal of Applied Reliability
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• v.15 no.4
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• pp.276-281
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• 2015

Purpose : The purpose of this study is to propose that domestic rail must the work to be done in the RCM system and railway operators are to present a direction to establish the efficient and systematic system based on this. Methods : In recent years, domestic railway accidents has decreased year rapidly every year. In particular, suicidal ideation was greater than 50% of the accidents is showing a larger decrease in the influence of the screen-door construction. However, the train delay has been maintained without major changes since 2010. The most important cause of the delay operation is a vehicle breakdown. This fact demonstrates that effective maintenance of the most important activities in the railway accident prevention activities. So we have to build a RCM system in which the characteristics of the domestic railway accident. Conclusion : We proposed what is necessary functionality and the function requires a railway operators in RCM railway systeml.

• Membrane and Water Treatment
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• v.10 no.1
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• pp.83-89
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• 2019

The most common way of reducing non-point source pollutants from agricultural areas is the installation of reservoirs. However, this method is only effective for surface runoff of settleable pollutants. This study was conducted to estimate the effect of interflow, baseflow, and surface runoff on pollutant runoff in a small agricultural catchment. Runoff of organic matters, SS, and T-P were directly proportional to the rainfall variation, while ammonia and nitrate were inversely proportional to the amount of rainfall. The interflow and baseflow was only 46% of the total stream flow, but the nitrate load reached 78%. The interflow as a nutrient transport pathway should be considered for managing a stream water quality. It requires careful attention and appropriate control methodology such as vegetation to consider the influence by interflow. The reservoir as a dry extended detention pond (DEDP) has function of nutrient captor.