• Title, Summary, Keyword: Dropper

Search Result 53, Processing Time 0.03 seconds

The Performance Analysis of TRC Dropper to improve fairness on DiffServ Networks (DiffServ 네트워크에서 공평성 향상을 위한 TRC Dropper의 성능 분석)

  • Kim, Hoon-Ki;Hong, Sung-Hwa
    • Journal of the Korea Society for Simulation
    • /
    • v.18 no.3
    • /
    • pp.91-102
    • /
    • 2009
  • The average window size is most closely related to average throughput. In order to improve fairness, the proposed dropper tries to control the window size of each flow to equal level by intentional packet drop. Intentional packet drop is performed only to the flows that have been occupied bandwidth in a large amount. Because of intentional packet drop, this flow cut down its transmission rate to a half. Accordingly, somewhat capacity of core link comes into existence. And other flow can use this new capacity of this link. Hence other flows have more throughput than before. In this paper, we propose the TRC (Transmission Rate Control) Dropper improving the fairness between individual flows of aggregated sources on DiffServ network. It has the fairness improvement mechanism mentioned above paragraph.

  • PDF

A Study on Fatigue Analysis of Dropper for High Speed Electric Railway (고속선용 드롭퍼 피로분석 연구)

  • Lee, Tae-Hoon;Park, Ki-Bum;Jeon, Yong-Joo;Ryu, Young-Tae;Cho, Yong-Hyeon;Lee, Ki-Won;Park, Young
    • Proceedings of the KSR Conference
    • /
    • /
    • pp.1445-1453
    • /
    • 2009
  • The dropper supports the contact wire and is attached using thimbles and various types of dropper clips on the catenary. Consequently droppers are subject to mechanical loads from friction and buckling during the passage of pantographs. If such mechanical loads occur repeatedly with every passing pantograph, it is possible that the dropper wire will break due to fatigue. In order to investigate failure causes for the high speed line dropper, theoretical analyses and experiments have been carried out. In this paper, mathematical formulas are derived for the prediction of the dropper static load. The measured values in the experiment agree well with the theoretical predictions. And, we performed measurement for the variation of forces on the dropper. To analyze the cause analysis on fracture of dropper wire, we have conducted experiment such as fatigue test of new products, SEM(Scanning Electron Microscope) and EDX(Energy Dispersive X-ray) of fractured specimens in the field. Finally, we also measured the vertical displacements when a pantograph moved at 300km/h under the Korean high speed overhead line.

  • PDF

Mechanical Loads of Dropper for High Speed Electric Railway (고속 전차선로 드로퍼에 대한 기계적 하중에 관한 연구)

  • Lee, Gi-Chun;Lee, Tae-Hoon;Lee, Jong-Woo
    • Journal of the Korean Society for Railway
    • /
    • v.14 no.3
    • /
    • pp.222-227
    • /
    • 2011
  • The dropper supports the contact wire and is attached using various types of dropper clips on the catenary. Droppers are subject to mechanical stress from buckling during the passage of pantographs. In order to investigate failure causes for the high speed line dropper, theoretical analyses and experiments have been carried out. In this paper, mathematical formulas are derived for the pre-sag of the dropper static load. The measured values in the experiment were similar to the theoretical predictions. To analyze the cause on fracture of dropper wire, we have conducted analysis such as SEM(Scanning Electron Microscope) of fractured specimens in the field and new specimens. Finally, we performed measurement for the variation of dynamic load on the dropper when a pantograph moved at 300km/h under the Korean high speed overhead line. If such mechanical load occur repeatedly with every passing pantograph, it is possible that the dropper wire will break due to fatigue. This results will be used for special management of high speed catenary system maintenance and life estimation of dropper.

Safety Assurance of Dropper Clamp in Overhead Catenary System(I) (전차선로 드롭바 클램프 안전성 확보(I))

  • Lee, Ki-Won;Cho, Yong-Hyeon;Park, Young;Min, Byung-Il;Kwon, Sam-Young;Seok, Chang-Sung
    • Proceedings of the KSR Conference
    • /
    • /
    • pp.223-226
    • /
    • 2007
  • In the electrical railway, for the improvement of a train speed, it is necessary to study not only the dynamic behaviors of overhead catenary system but the fatigue behaviors of components for a safety assurance according to the increase of vibration level. One of the critical components in the system is a dropper. Therefore, the dynamic force acting on a dropper was measured in the Chungbuk Line and analyzed to figure out the dynamic characteristics the dropper. And in order to assure the safety of dropper clamp and cable, we proposed a test facility as well as test method based on the test results For the further study, we will measure the dynamic forces in the conventional line and high-speed line and make up the test condition, so that the safety of dropper clamps can be assured.

  • PDF

Prediction of the force on the dropper according to the pre-sag (사전이도 적용에 따른 드로퍼에 작용하는 하중 예측)

  • Lee, Ki-Won;Cho, Hyeon-Young;Chang, Sang-Hoon;Kim, Hyung-Chul
    • Proceedings of the KSR Conference
    • /
    • /
    • pp.972-977
    • /
    • 2009
  • For the improvement of a train speed in the conventional line from overhead system point of view, it is necessary to approach not only in the aspect of the increasement of tension for catenary but the application of a pre-sag. A certain tension acting on a dropper is removed when it is slack by the pantograph passing. Right after the pantograph passes, the dynamic force caused by the mass of contact wire acts on the dropper. If the pre-sag is applied to the catenary, the static force on the dropper is increased. For the assurance of the safety for the dropper, it is necessary to predict the dynamic force. The purpose of this study is to predict and analyze the force on the dropper according to the applied pre-sag.

  • PDF

Development of Calcutation Software for Dropper Length (전차선로 드롭바 길이 계산프로그램 개발)

  • Lee Kiwon;Kwon Sanmyoung;Kim Joorak;Jang Donguk
    • Proceedings of the KSR Conference
    • /
    • /
    • pp.421-426
    • /
    • 2003
  • Dropper which can get to suspend contact wire should be installed with a uniform distribution, so that electric locomotive can have good characteristics of current collection. Because dropper distribution is changed according to a circumstances in the construction field, it is hard to calculate and construct a overhead line. Therefore, in this study, a program was developed to calculate the dropper length in the normal and elevation section. Through the program, it is possible to perform a accurate construction of overhead line and contribute to a improvement of current collection as well.

  • PDF

The Cause Analysis on Fracture of Dropper Clamp in Catenary System (전차선로 드로퍼 클램프 파단 원인 분석)

  • Kim Jung-Nam;Kwon Sung-Tae;Kang Kae-Myung
    • Proceedings of the KSR Conference
    • /
    • /
    • pp.909-914
    • /
    • 2004
  • This study investigate the cause analysis on fracture of dropper clamp in catenary system. Dropper clamp is using as a holder between messenger wire and contact wire in catenary system. To analyze the cause analysis on fracture of dropper clamp, we have conducted experiment such as tension withstand strength test, holding strength test of a new products, SEM and EDX of field fractured specimens.

  • PDF

A dropper length calculation method of the elevating span in overlap area (무효 인상 경간에서 드로퍼 길이 계산 기법)

  • Kwon, Sam-Young;Lee, Ki-Won;Cho, Yong-Hyeon
    • Proceedings of the KSR Conference
    • /
    • /
    • pp.1503-1510
    • /
    • 2011
  • The dropper length calculation method about the normal same encumbrance spans is well known independent to whether the pre-sag is given or not. But, the dropper length calculation method for the elevating span which consists in the end area of a tensioning section and normally consists with overlaps is not well known. In this study, firstly, we investigate the dropper length calculation method about the elevating span whether the insulator is contained in or not, we also recognize the effect of dropper length due to the change of the take-off point. Secondly, we very this calculation method with a catenary sample data and check again with Gyeongbu HSL design data.

  • PDF

Study of Current Collection Performance according to Dropper Spacing for Catenary (전차선 드로퍼 간격에 따른 집전성능 분석)

  • 권삼영;이기원;창상훈
    • Proceedings of the KSR Conference
    • /
    • /
    • pp.310-317
    • /
    • 1999
  • This paper presents study of collection performance according to dropper spacing for catenary Static characteristics analysis, dynamic simulation, stress and wear analysis for different 5 catenary configurations according to dropper spacing are performed. And collection performance for TGV-Nord catenary system is also analyzed in order to compare and evaluate.

  • PDF

A Study on Durability Standard Specification of the Dropper Clamp of Catenary for High Speed Railway (고속철도 전차선로 드로퍼 클램프 내구성 기준 정립에 관한 연구)

  • Oh, Wan-Shik;Yang, In-Dong;Park, Byung-Gon;Hong, Seok-Jin;Kim, Seong-Cheol
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.66 no.9
    • /
    • pp.1431-1436
    • /
    • 2017
  • The high-speed railway of catenary system, supplies a stable electric power supply to the train by satisfying the special conditions between pantograph and trolley wire, which operates more than 250km/h mutually sliding and feeding electric lines. According to Korean Railway Standard KRS PW 0026-13 (R), the standard for the grip strength of the dropper clamp in conventional line is established, but the high-speed railway line is not yet. When the grip strength of the dropper clamp is detached from the catenary line of the high-speed railway line, various problems may occur, such as damage to the pantograph due to the collision and arcing. In this paper, it is expected to be used as a basic data for establishing the durability criteria of the high-speed railway dropper clamp by verifying the dropper clamp on the Gyeong-bu and Honam high-speed line.