• Title, Summary, Keyword: 궤도틀림

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Characteristic Analysis of Permanent Deformation in Railway Track Soil Subgrade Using Cyclic Triaxial Compression Tests (국내 철도 노반 흙재료의 반복재하에 따른 영구변형 발생 특성 및 상관성 분석)

  • Park, Jae Beom;Choi, Chan Yong;Kim, Dae Sung;Cho, Ho Jin;Lim, Yu Jin
    • Journal of the Korean Society for Railway
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    • v.20 no.1
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    • pp.64-75
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    • 2017
  • The role of a track subgrade is to provide bearing capacity and distribute load transferred to lower foundation soils. Track subgrade soils are usually compacted by heavy mechanical machines in the field, such that sometimes they are attributed to progressive residual settlement during the service after construction completion of the railway track. The progressive residual settlement generated in the upper part of a track subgrade is mostly non-recoverable plastic deformation, which causes unstable conditions such as track irregularity. Nonetheless, up to now no design code for allowable residual settlement of subgrade in a railway trackbed has been proposed based on mechanical testing, such as repetitive triaxial testing. At this time, to check the DOC or stiffness of the soil, field test criteria for compacted track subgrade are composed of data from RPBT and field compaction testing. However, the field test criteria do not provide critical design values obtained from mechanical test results that can offer correct information about allowable permanent deformation. In this study, a test procedure is proposed for permanent deformation of compacted subgrade soil that is used usually in railway trackbed in the laboratory using repetitive triaxial testing. To develop the test procedure, an FEA was performed to obtain the shear stress ratio (${\tau}/{\tau}_f$) and the confining stress (${\sigma}_3$) on the top of the subgrade. Comprehensive repetitive triaxial tests were performed using the proposed test procedure on several field subgrade soils obtained in construction sites of railway trackbeds. A permanent deformation model was proposed using the test results for the railway track.

Dynamic Performance Evaluation of New Type PSC Railroad Bridges (신형식 PSC 철도교량의 동적성능 평가)

  • Choi, Sanghyun
    • Journal of the Society of Disaster Information
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    • v.7 no.4
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    • pp.259-265
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    • 2011
  • After the commercial opening of the KTX in 2005, the high speed railroad has been rapidly emerged as the major transportation means due to its high energy efficiency. Recently, the government has announced its plan to build the future transportation system around the high speed railroad. Based on this policy, the existing lines as well as the lines under construction or design are planning to increase design speed. In this paper, the suitability of the mid-span PSC girder bridges for the high speed railroad is evaluated via dynamic analysis. IT, Precom, and WPC girder bridges are considered for the purpose of this study and, for comparison, the identical modeling method and the analysis technique are utilized. The performance indices used for dynamic performance evaluation are the natural frequency, the vertical displacement, the end axial displacement, track irregularity, etc. The KTX train is utilized as a dynamic load, and the dynamic analysis is performed up to the train speed of 420km/hr with the increment of 10km/hr.

Development of models for measuring track irregularities using accelerometers (가속도계를 이용한 궤도틀림 측정용 모델의 개발)

  • Lee, Jun-Seok;Choi, Sung-Hoon;Kim, Sang-Soo;Kim, Seog-Won
    • Proceedings of the KSR Conference
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    • pp.303-310
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    • 2011
  • This paper is focused on development of models for measuring lateral and vertical track irregularities from corresponding accelerometers of an in-service high-speed train. Generally, the track irregularity was measured by a special railway inspection vehicle or system with contact or non-contact sensors. However, the sensors are very expensive and vulnerable to a harsh environment. Displacement estimation from an inertial measurement unit and its wave-band filtering was already developed in the previous study, and it was found that their results included not only the track irregularities but also other information such as phase delay of the applied filters, and suspension and conicity of the wheel. To identify the track irregularities from those results, a compensation filtering method was proposed. Each directional compensation filter was derived by using a system identification method with the estimated directional displacement as input and the corresponding track irregularities as output. In this paper, they are integrated into a model for each direction and applied to the measured lateral and vertical acceleration data from the axle-box and bogie of an in-service high-speed train. Their results are compared with the data from the track geometry measurement system. From the comparison, the proposed models are a useful tool for the measurement of the track irregularities using accelerometers of in-service high-speed trains.

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A Study on the Behaviour of the Station Structure due to Adjacent Construction (근접시공에 따른 정거장구조물 거동특성에 관한 연구)

  • Chung, Jeeseung;Kim, Manhwa;Lee, Sungil;Kim, Hongjoo;Shin, Youngwan
    • Journal of the Korean Geoenvironmental Society
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    • v.17 no.11
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    • pp.55-64
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    • 2016
  • Recently, it has been made many adjacent construction of inter-facility by the expansion of urban infrastructure facilities using the underground space. The complaints relating to the stability of the facility by adjacent construction is common. In this study, it was conducted for the subway line 5 Gimpo airport station structure in the upper Gimpo urban railway to determine the behavior characteristics of station structure according to adjacent construction. It was performed evaluation of the safety zone and excavation method for station structure. And after a review of damage evaluation, track irregularities and structural calculation by using a numerical analysis, stability of the station structure according to adjacent construction was evaluated to be secured. This study is expected to be used as basic data in advance if you need to review the effects of nearby structure according to adjacent construction.

Measurement of Track geometry with HSR350X (한국형고속열차를 이용한 궤도 틀림 측정결과 비교분석)

  • Im, Yong-Chan;Kim, Sang-Soo;Park, Choon-Soo;Kim, Ki-Hwan
    • Proceedings of the KSR Conference
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    • pp.278-282
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    • 2007
  • The riding comfort and the durability of train are effected by the rail irregularities such as track gauge, superelevation, alignment, longitudinal level, twist, cant and cross level. Inspection and estimation of irregularities are very important to maintain the rail condition. Generally, the EM120 has been utilized to measure the rail irregularities once a month in Korea. However, the EM120 can be operated at night time only, because the inspection speed of EM120 is much slower than the speed of high-speed trains. Also, the EM120 is too slow to inspect effectively for the whole commercial line. Therefore, we have mounted the track inspection system on the High-Speed Rolling Stock 350 eXperimental (HSR350X) and measured the rail irregularities to confirm the condition of a rail while running 300km/h. In this paper, the track inspection system mounted on HSR350X is mainly considered, and the measured results through test run are introduced.

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Track Longitudinal Irregularities at Bridge Deck Expansion Joint with ZLR(Zero Longitudinal Restraint) (활동체결장치가 설치된 교량상판 신축이음부에서의 궤도고저틀림에 미치는 영향)

  • Eom, Jong-Woo;Kim, Si-Chul;Kim, In-Jae
    • Proceedings of the KSR Conference
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    • pp.1093-1098
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    • 2007
  • In designing the high-speed railroad track, it is important to utilize appropriate track components to maintain uniform stiffness and ensure track alignment within the tolerance set for that system. In this regard, continuous welded rails (CWRs) were introduced to the Korean railways. Yet the installation of CWRs can result in an adverse impact due to the track/structure interaction on bridge sections yielding variations in the stiffness at the expansion joints. It may also impose additional axial force, generate excessive stress or deflection on track, and loosen the ballast at the ends as a bridge deck contracts or expands owing to a thermally-induced dynamic response. The risk is even greater in a long bridge deck, resulting in track longitudinal irregularities, deteriorating passenger's comfort, and increasing maintenance efforts. This study evaluates the performance of ZLR and their impact on track longitudinal irregularities through the track measuring results on a test section installed the ZLR in order to minimize the thermally-induced responses and the maintenance efforts for the high speed railway bridges.

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Development of Magnetic Torquer for Satellite Attitude Control (인공위성 자세제어용 Magnetic Torquer 개발)

  • Son, D.
    • Journal of the Korean Magnetics Society
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    • v.18 no.2
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    • pp.54-57
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    • 2008
  • Magnetic torquer, which uses torque between magnetic dipole moment and earth magnetic field, has been used to control attitude of satellites. In this work, we developed a magnetic torquer for small scientific satellite and test under environmental conditions of the satellite launching and orbital motion have been carried out. The developed magnetic torquer shows saturation magnetic dipole moment of $15Am^2$, linearity of 0.3 % in the range of ${\pm}12Am^2$, mass of 0.46 kg, and power consumption of 1 Watt at magnetic dipole moment of $10Am^2$.

Track Deterioration Prediction and Scheduling for Preventive Maintenance of Railroad (궤도 유지보수를 위한 틀림진전 예측 및 일정최적화)

  • Kim, Dae-Young;Lee, Seong-Geun;Lee, Ki-Woo;Woo, Byoung-Koo;Lee, Sung-Uk;Kim, Ki-Dong
    • Proceedings of the KSR Conference
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    • pp.1359-1370
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    • 2008
  • In the track geometry such as rails, sleepers, ballasts and fastener, track deterioration occurs by repetitive train weight and the high-speed railway takes a trend faster than normal. Track deterioration of over threshold value harms ride comfort and furthermore affect in trains safety seriously. An organic and systematic track maintenance system is very important because a trend of the track deterioration effects on track life-cycle and running safety. Also costs of the railway track permanent way and its maintenance are extremely large, forming a significant part of the total infrastructure expenditure. Therefor reasonable and efficient track maintenance has to be planed on a budget. It is required to carry out not only corrective maintenance but preventive maintenance for the track maintenance. In order to perform maintenance jobs in the boundary of the machines and resources given regarding the type and amount jobs, it is necessary to determine feasible or optimal scheduling considering the priority. In this study, the system organization and required functions for the development of track maintenance system supported track deterioration prediction and optimal scheduling are proposed.

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Status of a launching state in international law (발사국의 국제법상 지위)

  • Lee, Joon
    • Current Industrial and Technological Trends in Aerospace
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    • v.7 no.2
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    • pp.3-11
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    • 2009
  • On August 25th, Korea launched KSLV-1(Naro), the first Korean launch vehicle with the payload of a small satellite. The launch itself was successful in that the first and second stage of the launch vehicle functioned properly but unfortunately the satellite was unable to be put into earth orbit due to the failure of a nose faring detachment. As the history of human space activities shows, it is recognized as a difficult task to be a launching state requiring efforts to obtain enough technical ability. But along with the technical ability, there has to be an understanding on international legal systems on space launch vehicle. It is because the launch may cause cross-border losses and because the launcher is regarded as a strategic technology resulting in international control. This paper aims to study the international status of launching state and to consider legal regimes necessary for launcher development.

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Study on The Modification of The Transition Curve to Increase Operating Speed of Existing Line (기존선 속도 향상을 위한 완화곡선 변경 방안 연구)

  • Kim, Jae-Bok
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.10
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    • pp.26-32
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    • 2019
  • The purpose of this study is to improve the running speed on a small-radius curved section on an existing train line. When the transition curve was extended, and the amount of movement in the horizontal direction tended to increase as the curve radius increased. The amount of increase in the transition curve extension was lowest when extending the curve radius, and the amount of horizontal movement was the lowest when changing the curve radius to a cosinusoidal curve. As a result of applying the pass rate after improvement to the Kyeongbu line, there was a time-shortening effect of 9.4 to 11.6% and a facial expression speed increasing effect when the curve radius was fixed and the transition curve was changed to a sinusoidal curve. In conclusion, the most effective way to improve the running speed on an existing train route is to change the image to concrete and to change the relaxation curve to a cosinusoidal curve. The amount of horizontal movement of the track is small, and the speed improvement effect is excellent.