• 제목, 요약, 키워드: CWR

검색결과 133건 처리시간 0.03초

무도상 교량 특성을 고려한 장대화 방안에 관한 연구 (A study for CWR on Steel Plate Girder Railway Bridge without Ballast)

  • 민경주;남보현;반걸용
    • 한국철도학회:학술대회논문집
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    • pp.706-711
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    • 2005
  • From the using CWR (Continuously Welded Rail) on steel plate girder bridges without ballast, axial forces are occurred from a temperature on CWR and girders. Because of the additional axial forces, studies in order to CWR and developments of devices are proceeding. The track system of steel plate girder bridges is poor. When CWR is used for the system, the resistance on sleepers is increased from a temperature. So it is increasing an effect on CWR and, for solving the effect, longitudinal forces for buckle are being decreased. It is possible that opposite cases can be happened and it is also compared and studied. Therefore, we present a reasonable model for analyzing CWR within the property of steel plate girder railway bridges in Korea. Furthermore, the results analyzed for stability is compared and evaluated with tests. Finally, a reasonable method for the installation of CWR on bridges without ballast is suggested.

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효소발효 백하수오의 고지혈증 흰쥐에 대한 지질대사 개선 효능 연구 (Lipid Improvement Effect of Fermented Cynanchi wilfordii Radix in Hyperlipidemia Rats)

  • 풍수김;노성수;오당섭;서영배
    • 대한본초학회지
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    • v.30 no.6
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    • pp.83-91
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    • 2015
  • Objectives : The present study was conducted to examine whether Cynanchi wilfordii radix (CWR) with or without fermentation has an ameliorative effect on hyperlipidemia in rats.Methods : We analyzed the contents of Conduritol F on Cynanchi wilfordii radix. The experimental animals were divided into six groups; normal diet fed group (N), high cholesterol fed control group (Con), Lovastatin 20 mg/kg (L), CWR-W 300 mg/kg (CWR-W), and CWR-F 300 mg/kg on hyperlipidemia model induced by feeding 1.25% cholesterol. Rats were administrated orally every day for 8 weeks. And lipid profile of serum and weight change were observed.Results : The vehicle displayed a markedly increased body weight and significantly increased liver and epididymal fat weight, however, the administration of CWR improved the body, liver, and epididymal fat weights. All drug treatment reduced significantly the serum level of total cholesterol and LDL-cholesterol elevated by intake of high cholesterol diet. TG displayed a reducing tendency all drug treatment, however, CWR-W decreased significantly. Atherogenic index and cardiac risk factor increased high cholesterol diet fed control group, while the administration of CWR-W and CWR-F decreased significantly. The major index of liver injury such as AST and ALT improved in all drug treatment.Conclusions : These results suggest that CWR extended the effect of lipid enhanced. Therefore CWR with or without fermentation may be useful for therapeutic treatment of clinical conditions associated with hyperlipidemia. Finally, these require more investigations about the action mechanism of CWR in the future.

기존선 급곡선부의 장대화 방안에 대한 연구 (A study on constructing CWR for railroad under operation)

  • 양신추;노혁천;김은;이종득
    • 한국철도학회:학술대회논문집
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    • pp.303-310
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    • 2001
  • The railroad under operation has very sharp curves and the state of ballast is somewhat deteriorated due to the traffic loads, which put some constraints in converting the conventional rails into CWR. In making CWR, the determination whether the ballast has sufficient capacity for resisting buckling must be made, quantitatively and qualitatively, and schemes to guarantee the required lateral resistance of ballast should be proposed. In this study, using the in-situ investigated data, the probability of buckling of CWR is given for several installation temperatures for CWR. The effect of tamping, DTS, and sleeper spacing are taken into account. The buckling probability is given as a function of curvature and installation temperature of CWR and works used to increase the ballast resistance capacity after tamping, i.e., DTS and reduction of sleeper sparing.

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곡선부 장대레일 궤도의 거동 특성에 관한 연구 (The Study on the Behavior of Curved CWR Track under Thermal Load)

  • 이원경;성덕룡;김만철;박용걸
    • 한국철도학회:학술대회논문집
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    • pp.426-436
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    • 2006
  • The use of the CWR track has increased consistently in the worldwide. Because the use of CWR track not only reduces the track maintenance cost, noise and vibration, but increases the life cycle of track components. Therefore, to increase train speed, improve riding condition and secure running stability, the necessity of study on making CWR is increasing. This study includes the development of a thermal buckling theory in the evaluation of curved track stability. The lateral stability of curved CWR is studied for track buckling prevention through the parameter studies. It studied the lateral buckling of the curved CWR track on the 3-D nonlinear analysis. The parameters include rail size, cant, track curvature.

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Penman-Monteith을 이용한 토마토와 파프리카의 증발산 모델 평가 (Assessment of Water Control Model for Tomato and Paprika in the Greenhouse Using the Penman-Monteith Model)

  • 솜늑 시리락;홍영신;김민영;이상규;백정현;곽강수;이현동;이재수
    • 시설원예ㆍ식물공장
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    • v.29 no.3
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    • pp.209-218
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    • 2020
  • ETc 손실을 보상하는데 필요한 물의 양을 작물 용수 요구량(Crop water requirement, CWR)로 정의되며, ETc 평가는 작물 필요 요구량을 정확하게 정량화하는 데 필요하며, 물 균형 계산에서 중요한 역할을 한다. 토마토와 파프리카의 실제 관수 요구량(Actual crop water, ACW)이 적절한 CWR인지 평가하였다. 토마토와 파프리카 재배에 적정한 AWC 예측 및 추정을 위하여 온실 내부 환경데이터를 Penman-Monteith을 이용하여 기준 작물 증발산(ET)을 계산한 후, 기준 증발산은 작물 상수(Kc;토마토-1.15, 파프리카-1.05)계수로 조정하였다. 토마토와 파프리카의 CWR과 ACW를 계산하여 비교 평가한 결과 ACW가 CWR을 대체할 수 있지만 파프리카의 ACW는 필요 이상으로 높게 나타났다. 또한, 토마토의 ACW는 1일 100 ~ 1,200 ml이고, 파프리카의 ACW는 1일 100 ~ 500 ml가 적절한 것으로 나타났다. 그러나, 스마트 온실에서 ETc의 정밀도를 높이려면, ETc가 CWR로 변환되고 ACW와 비교하기 위해서 클래스 A팬 설정이 필요하다. 향후 실시간으로 CWR을 측정하기 위한 시뮬레이션 프로그램 연구가 필요하다.

기존선 교량구간의 장대레일화 방안 연구 (A study on constructing CWR for railroad on bridges)

  • 양신추;김은;노혁천
    • 한국철도학회:학술대회논문집
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    • pp.311-318
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    • 2001
  • The CWR, when installed on the bridge, may introduce extra responses in displacement, stress etc. due to the expansion of bridge girders. To release these responses, a special concern must be put on the CWR on bridges, especially for the long span bridges. Since the risk of derailment of vehicle due to buckling or breakout of the rails on bridges is of importance, the establishment of appropriate guidelines to check the performance of CWR on bridges is crucial for safe operation of train. In this study, using the program CWRAP, specialized for response of rails on bridges, several schemes for constructing CWR on bridges are suggested. In audition, a special concern is given to the bridge with sharp curve which is vulnerable to buckling due to temperature loads.

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열차하중에 따른 교량 신축부 장대레인 축력 연구 (A study on the axial force on the CWR of the suport rotation)

  • 박준오;김종민;김우진
    • 한국철도학회:학술대회논문집
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    • pp.460-469
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    • 2006
  • It is widely known that the temperature variation introduces the axial force along a CWR(Continuous Welded Rail) in the railway bridges. Additional axial forces are generated due to many other reasons. These includes the interaction between the bridge girder and the CWR; acceleration or deceleration of the vehicles; support rotation (or deflection) of the girder. Among aforementioned reasons, this study investigates the influence of the support rotation on additional axial forces throughout the numerical study and the field test. Several strains gauges are installed along the CWR and the strains are measured under passing trains. It is expected that the elaborated estimation of the axial force on CWR will be beneficial for future railway maintenance.

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도상횡저항력의 확률분포 특성에 따른 CWR 궤도의 좌굴 민감도 (Buckling Sensitivity of CWR Tracks according to the Characteristics of the Probability Distribution of the Lateral Ballast Resistance)

  • 윤경민;배현웅;강태구;김명수;임남형
    • 한국철도학회:학술대회논문집
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    • pp.423-426
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    • 2011
  • The excessive axial load occurred in an immovable zone of continuous welded rail(CWR) tracks threatens the security of running trains due to the track buckling in extreme hot summer. The influence factors, such as rail temperature for compressive stress, ballast resistance for track stiffness and initial imperfection of track for tracks irregularity are uncertain track parameters that are randomly varied by climate conditions, operating conditions and maintenance of track etc. So, buckling of CWR tracks has very high uncertainties. Therefore, applying the probabilistic approach method is essential in order to rationally consider the uncertainty and randomness of the various parameters. In this study, buckling sensitivity analysis was carried out with respect to the characteristics of probability distribution of lateral ballast resistance using the buckling probability evaluation system of CWR tracks developed by our research team.

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CWR 궤도의 좌굴 안정성에 대한 결정론적 해석과 확률론적 해석 비교 (A Comparative Study between the Deterministic and Probabilistic Approach Analysis on Buckling Stability of CWR Tracks)

  • 배현웅;최진유;신정상;김종중;임남형
    • 한국철도학회:학술대회논문집
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    • pp.988-992
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    • 2011
  • The buckling characteristics of the continuous welded rail track(CWR) is uncertainly varied by many influence factors, such as rail temperature, operating conditions of a train and maintenance of the track etc. Therefore, applying the probabilistic approach method is essential to rationally consider uncertainty and randomness of the various parameters that affect the track buckling. In this study, the probabilistic approach analysis was carried out and the results were compared with the deterministic approach using the buckling probability evaluation system of CWR tracks developed by our research team. From the comparison, it was identified that a probabilistic approach can quantitatively assess the reliability of the CWR tracks based on failure probability and can be used as a tool for decision making in track design, maintenance and operating etc.

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장대레일 좌굴 변수 : 채결재, 칠목들림 (Buckling Parameters of CWR Track: Fastner, Uplift of Tie)

  • 한상윤;임남형;한택희;강영종
    • 한국철도학회:학술대회논문집
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    • pp.763-768
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    • 2004
  • CWR(Continuous Welded Rail) has many advantage over the conventional jointed rail track. The use of CWR track not only reduces the track maintenance cost, but increase the life cycle of track components. As the use of CWR increases in track structures, derailing disasters associating with track buckling also increase in great numbers due to high compressive thermal stress. Despite the importance, the number of studies relevant to the instability is quite limited. In this paper, It considers the contribution of rail-pad-fastener resistance, uplift of tie and nonlinear analysis. Influence of various track components on CWR track temperature and mode shape were characterized.

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