• 제목, 요약, 키워드: CWR

검색결과 133건 처리시간 0.041초

판형교 장대레일 부설에 따른 계측 및 평가 (Test and Evaluation of the CWR on Steel Plate Girder Railway Bridge)

  • 민경주;심현우;안용득
    • 한국철도학회:학술대회논문집
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    • pp.568-573
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    • 2005
  • To the installed CWR (Continuously Welded Rail) on steel plate girder bridges without ballast, shoes were replaced by the shoe for reduced axial force. During 9 months, from summer to winter, expansion by a temperature on girders, axial forces by a temperature on CWR, etc. are tested and the results are evaluated. Also, with the numerical analysis, the results - axial forces by a temperature on CWR, deformations of girders, etc. are compared and evaluated. From the longitudinal displacement on girders, occurred by run of trains, because of looking for the stability, the bearings for reducing axial forces are applied to the railway bridges. It is verified that the bearings for reducing axial forces disperse the axial forces by a temperature from the measurement of the forces on CWR of plate girder bridges,.

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장대레일과 교량의 상호작용 해석을 통한 교량제원 매개변수 분석 (Parametric Study on Properties of bridge by CWR(Continuous Welded Rail) and Bridge Interaction Analysis)

  • 김종민;한상윤;임남형;강영종
    • 한국철도학회:학술대회논문집
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    • pp.1460-1465
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    • 2007
  • CWR(Continuous Welded Rail) and bridge interaction produce rail force, bridge displacement and rail/bridge relative displacement. Each of these has limitation by many codes. In this paper, analysis of interaction has been carried out by using foreign codes(UIC 774-3 R code of Europe etc.) because there is no code about interaction between rail and bridge in Korea. Recently, railway bridges with CWR has been constructed for structural and economical reasons. When designer plans railway bridges, design a bridge model first and then investigate railway forces and displacement by interaction analysis. If these results go out bounds from limitation, designer plans railway bridges again and again. In this paper, using the parametric study on CWR and railway bridge interaction, railway bridge parameters such as length of bridge span, area of bridge, moment of inertia, stiffness of pier, etc. are presented. It helps preliminary design of railway bridges.

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가동단 마찰계수가 장대레일 축력 안정성에 미치는 영향 검토 (Review of effects of friction coefficient of moving bearing on Stability of CWR)

  • 유제남;최영준;양신추
    • 한국철도학회:학술대회논문집
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    • pp.812-817
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    • 2004
  • Recently drastic improvement of railway technology has been accompanied by the construction of very high-speed tracks. It should be noticed that Continuously Welded Rail(CWR) has played significant role in technical development of railway and that installation of CWR is now being scheduled on existing lines as well as newly-built lines. In general, interaction between CWR and bridge deck takes place on bridge section and additional axial force and displacement is to be developed owing to temperature and braking/acceleration forces. This interaction is known to be mainly governed by span organizations and arrangements of foot bearings. In common practice, movable bearing is stationed and designed on the assumption that it is not able to transfer the horizontal force of upper decks. However, it is well known that horizontal resistance is developed in movable bearings due to friction and that friction coefficient of movable bearing is ranged from 0.03 to 0.20 depending on the material of bearings and magnitude of reactions. Therefore, it is easily reasoned out that friction of movable bearing can influence the mutual behavior of CWR and bridge decks. Suggested in this study is to investigate the validity and efficiency of friction effect of movable bearings in controlling the axial force and displacement of CWR on continuous railway bridges.

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교량신축과 분기기의 이격거리에 따른 교량상 분기기 축력특성 연구 (A Study on the axial force in CWR with Turnout according to Distance between Bridge Expansion Joint and Turnout)

  • 최진유;이현정;양신추;정장용;유진영
    • 한국철도학회:학술대회논문집
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    • pp.1050-1055
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    • 2008
  • The demand on a turnout layed on a bridge is rising owing to the increasing number of stations on the viaduct. And also the demand on a turnout with CWR is rising to upgrade running speed of the passing train. A CWR with turnout is subjected to additional axial force induced by the thermal expansion of bridge as well as lead rail of turnout. The additional axial force is closely related with the distance between bridge expansion joint and turnout when it is located near the movable bearing of bridge, and it is required to keep some distance to prevent excessive axial stress in CWR. But, there is no guideline in specification for the proper distance from E.J. to turnout, and it caused problem in planning turnout or bridge. So, it this study, the parametric study to investigate the effect on axial stress in CWR with turnout according to span length and distance between bridge expansion joint and turnout was performed. From the results of numerical analysis, it was found out that $5{\sim}30m$ distance is required to prevent excessive axial in CWR for span length less 90m.

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장대레일 궤도의 안정성에 미치는 체결장치의 실험적 연구 (An Experimental Study of Fastening System on CWR(Continuous Welded Rail) Track Stability)

  • 김정훈;한상윤;임남형;강영종
    • 한국철도학회:학술대회논문집
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    • pp.317-324
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    • 2007
  • Until now, the railway has been constructed using track with jointed rails of relatively short lengths to allow thermal expansion in hot summer months. These joints weaken the track structurally and increase track maintenance cost and power consumption of the running train. The CWR(Continuous Welded Rail) Track is the solution of these drawbacks. Although the CWR track not only reduces the track maintenance cost but also increases the life cycle of track components, the stability of the track is highly affected by change of temperatures and vehicle load. A three dimensional nonlinear analysis which considers rail, fastening system and tie has been performed to understand structural behavior of the CWR track. In this case, the translational and rotational stiffness values of fastening system have not been studied. The fastening system makes ties and rails connect. In this study, the stiffness values of various types of fastening systems which consist of clips, rail-pads and insulators are determined by the experiment. The experimental results of the fastening system are compared with the results of parametric study that is performed to investigate the sensitivity of fastening system on stability of CWR track.

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백수오(白首烏)의 항산화 효능 및 모유두 세포의 5α-reductase mRNA 발현 억제 효능 (Investigation of Antioxidant Activity of Cynanchi Wilfordii Radix and Inhibitory Effect of 5α-reductase mRNA in Human Dermal Papilla Cells)

  • 조남준;최영호;전해리;이웅희;김기광;한효상
    • 동의생리병리학회지
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    • v.31 no.6
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    • pp.374-379
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    • 2017
  • Hair loss affects interpersonal relationships and causes psychological stress. In this study, we investigated the antioxidant activity of Cynanchi Wilfordii Radix (CWR) and its effects on dermal papilla (DP) cells. Antioxidant efficacy was examined by ABTS assay. To confirm the effect on cell activity, MTS assay was performed and cell count was directly measured by hemocytometer. The mRNA expression of genes involved in hair formation and hair loss formation was confirmed by quantitative RT-PCR. CWR has a strong antioxidant activity. Cell viability of DP cells was increased to 118.5% by treatment of 0.5 mg/ml CWR for 24 hours, but the effect on the cell number was insignificant. These results suggest that CWR increases mitochondrial activity without promoting cell proliferation. Treatment of DP cells with 0.5 mg/ml CWR resulted in 48.5% reduction of mRNA expression of type 2 $5{\alpha}$-reductase, a major cause of male hair loss. In addition, mRNA expression of bone morphogenetic pretein (BMP), fibroblast growth factor (FGF)7, and FGF10, which are closely related to hair growth, was also decreased. Reactive oxygen species (ROS) acts as a cause of hair loss. The excellent antioxidant efficacy of CWR is thought to be able to effectively remove ROS. The dihydrotestosterone produced by type 2 $5{\alpha}$-reductase in DP cells is a potent inducer of male pattern hair loss. The inhibitory effect of type 2 $5{\alpha}$-reductase mRNA on DP cells induced by CWR may induce a positive therapeutic effect of male pattern hair loss.

온도하중을 고려한 장대레일 궤도의 안정성 해석 (Stability of Continuous Welded Rail Track under Thermal Load)

  • 강영종;임남형;신정렬;양재성
    • 한국강구조학회 논문집
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    • v.11 no.3
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    • pp.281-290
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    • 1999
  • 수십 년 동안, 철도는 차량의 운영과 조작 기술에 맞추어 짧은 길이의 레일을 서로 신축 이음을 두고 연결한 궤도를 이용하여 건설되었다. 그러나 이러한 신축이음들은 궤도 손상과 유지비 증가 등의 많은 단점들을 유발시켰다. 그래서, 철도 기술자들은 차량, 용접, 체결의 기술이 발전함에 따라 열차 하중, 속도의 증가를 위해 레일 사이의 신축 이음을 제거하는 데 많은 관심을 가지게 되었다. 그래서 최근 등장한 것이 기존 레일의 단점들을 해소할 수 있는 CWR궤도이다. 그러나 이러한 CWR궤도는 기존 레일의 단점을 극복할 수 있었으나 레일의 장대화에 따른 온도 하중으로 인한 레일의 좌굴 문제를 야기시켰다. 본 논문에서는 유한 요소 해석을 이용하여 선형 좌굴 해석을 위한 CWR 궤도의 모델과 해석 프로그램인 CWRB를 개발하였다. 레일의 해석 모델은 레일요소 당딤을 고려한 14개의 자유도로 나타내었으며, 체결재, 침목, 도상 저항력을 스프링 요소를 사용하였다. 장대레일의 온도하중에 의한 좌굴 온도 및 모드의 분석으로 장대레일의 온도 좌굴 특성을 고찰하였다.

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도상이 장대 레일의 선형 온도 좌굴에 미치는 영향 (Effect of Track Resistance on Linear Thermal Buckling Characteristics of CWR)

  • 강영종;임남형;신정렬;양재성
    • 한국철도학회:학술대회논문집
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    • pp.580-587
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    • 1998
  • For many decades, the railway was constructed using tracks with jointed rails of relatively short lengths in accordance with rolling and handling technology. The joints cause many drawbacks in the track and lead to significant maintenance cost. So, railroad engineers became interested in eliminating joints to increase service loads and speeds by improving rolling, welding, and fastening technology, Continuous welded rail(CWR) track has many advantages over the conventional jointed-rail track. But in the case of the elimination of rail joints, it may cause the track to be suddenly buckled laterally by thermal and vehicle loads. Thermal loads are caused by an increase in the temperature of railway track. In this paper, CWR track model and CWRB program are developed for linear buckling analysis using finite element method(FEM). The finite element discretization is used with a total of 14 degrees of freedom for each rail element. The stiffness of the fastener, tie, and ballast bed are included by a set of spring elements. The investigation on the buckling modes and temperature of CWR track is presented in the paper.

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궤도 안정성에 대한 장대레일과 체결구의 민감도 (Sensitivity of the Continuous Welded Rail and the Fastener on the Track Stability)

  • 한상윤;박남회;임남형;강영종
    • 대한토목학회논문집
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    • v.26 no.4A
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    • pp.719-726
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    • 2006
  • 전세계적으로 널리 사용되고 있는 장대레일 궤도는 유지 보수 비용을 절감시키고, 궤도구성요소들의 수명이 길어진다는 장점을 가지고 있다. 그러나, 혹서기에 레일의 높은 온도 상승으로 인해 장대레일 궤도에는 매우 큰 압축력이 작용하게 되고, 이는 장대레일 궤도의 장출(좌굴)을 발생시켜 열차의 탈선으로 인한 사고로 이어진다. 본 연구에서는 장대레일 궤도의 좌굴에 많은 영향을 주는 궤도의 구성요소들 중에서 레일의 단면적과 단면2차모멘트 그리고 체결구의 파손과 병진 및 회전방향의 강성이 장대레일 궤도의 좌굴에 미치는 민감도를 파악하였다.

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장대레일궤도의 온도좌굴에 영향을 미치는 매개변수 연구 (Parametric Study on Thermal Buckling of CWR Tracks)

  • 최동호;김호배
    • 한국철도학회:학술대회논문집
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    • pp.295-302
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    • 2001
  • The lateral stability of curved continuous welded rail (CWR) is studied fur buckling prevention. This study includes the influences of vehicle induced loads on the thermal buckling behavior of straight and curved CWR tracks. quasi-static loads model is assumed to determine the uplift region, which occurs due to the vertical track deformation induced by wheel loads of vehicle. Parametric numerical analyses are performed to calculate the upper and lower critical buckling temperatures of CWR tracks. The parameters include track lateral resistance, track curvature, longitudinal stiffness, tie-ballast friction coefficient, axle load, truck center spacing, and the ratio of lateral to vertical vehicle load. This study provides a guideline for the improvement or stability for dynamic buckling in on tracks.

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