• Title, Summary, Keyword: Dropper

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Performance Analysis of REDP Marker with a combined Dropper for improving TCP Fairness of Assured Services

  • Kyeong Hur;Lee, Yeonwoo;Cho, Choon-Gen;Park, Hyung-Kun;Eom, Doo-Seop;Tchah, Kyun-Hyon
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.7B
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    • pp.711-721
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    • 2004
  • To provide the end-to-end service differentiation for assured services, the random early demotion and promotion (REDP) marker in the edge router at each domain boundary monitors the aggregate flow of the incoming in-profile packets and demotes in-profile packets or promotes the previously demoted in-profile packets at the aggregate flow level according to the negotiated interdomain service level agreement (SLA). The REDP marker achieves UDP fairness in demoting and promoting packets through random and early marking decisions on packets. But, TCP fairness of the REDP marker is not obvious as fur UDP sources. In this paper, to improve TCP fairness of the REDP marker, we combine a dropper with the REDP marker. To make packet transmission rates of TCP flows more fair, at the aggregate flow level the combined dropper drops incoming excessive in-profile packets randomly with a constant probability when the token level in the leaky bucket stays In demotion region without incoming demoted in-profile packets. It performs a dropping in the demotion at a domain boundary only if there is no prior demotion. The concatenate dropping at multiple domains is avoided to manifest the effect of a dropping at a domain boundary on TCP fairness. We experiment with the REDP marker with the combined dropper using ns2 simulator for TCP sources. The simulation results show that the REDP marker with the combined dropper improves TCP fairness in demoting and promoting packets by generating fair demoted in-profile traffic compared to the REDP marker. The effectiveness of the selected drop probability is also investigated with showing its impact on the performance of the REDP marker with the combined dropper.

The Improvement of Material Quality for Dropper Clamp on the Catenary System (전차선로 드로퍼 클램프 재질 향상에 관한 연구)

  • 김연근;창상훈;오기봉
    • Proceedings of the KSR Conference
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    • pp.547-552
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    • 2002
  • The research sees the catenary dropper clamp using a test equipment which is using actual sample in the field. This test helps the quality improvement of material. For raising the reliability of data, classified it by type and tests especially in the multiple sample but it was under testing in the sample of decimal at circumstance. From the accuracy side of research data it was insufficient because the dropper clamp was in small quantity but it contributes in quality of material improvement. The quality of material data which it gets with spectroscopic was not accurate so hereafter it needs to follow wet analysis and precise analysis to join in the test which is detailed comes to accomplish with the data accuracy.

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A Study on the Dynamic Characteristics of Catenary (가선계의 동특성 해석)

  • 최병두;김정수
    • Proceedings of the KSR Conference
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    • pp.525-532
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    • 1998
  • In this study, dynamic characteristics of catenary that supplies electrical power to high-speed trains is investigated. A particular emphasis is placed on the effect of droppers on the dynamic response of the contact wire, a dropper is an element that connects the contact wire with the messenger wire so as to maintain near uniform compliance, Finite element model compressing 3 spans is constructed. For the linear model, droppers are modeled as linear springs with various stiffness values. Modal analysis is performed to obtain the natural frequencies and modes and the variation in the modal density distribution for changing stiffness values are noted. Impulse response is also obtained through computer simulation. In practice, dropper is a nonlinear element with low stiffness in compression and high stiffness in tension. Hence, dropper can be modeled as a nonlinear spring with hi-directional stiffness values. Impulse and harmonic responses are obtained for the nonlinear model through simulation. The responses aye also compared with the linear cases.

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A Study on the Efficient Stabilization of Dropper Clamp for Messenger and Trolley Wire (전차선 및 조가선 접속지지용 드롭바크램프의 성능 안정화 연구)

  • Jung, Hyun-Soo;Lee, Seung-Hyuk;Ree, Cheol-Jick;Lee, Hyung-Kwon
    • Proceedings of the KIEE Conference
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    • pp.156-158
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    • 2004
  • In the ATs(Auto-Transformers)-fed AC electric railroad system, the trolley wire with high power is supported with a messenger by the dropper. As the dropper maintains the height of the trolley wire and plays a role in distributing the supply power, it should be stabilized in that an electric and mechanical character accord ins the change of the open air circumstance and constructed easily. Consequently, this paper propose C5111 Sn(3.5$\sim$4.5%) and hexagonal round bolt for the way of the efficient stabilization as a result of the test that the correlation of the Sn content and the change of temperature affect a character of product.

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Analysis of Contact and Separation between the Catenary and the Pantograph of a High-speed Electrical Train Considering the Dropper Positions (드롭퍼 위치를 고려한 고속전철 전력선과 급전기의 접촉 분리 해석)

  • Lee, Ki-Su
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.17 no.5
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    • pp.427-436
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    • 2007
  • The catenary of a high-speed electrical train is modeled by the finite elements with the upper suspension wire, lower contact wire, and droppers, and the dynamic contact between the catenary and the pantograph is numerically analyzed by solving the whole equations of motion of the pantograph and the catenary system subjected to the contact condition. For the stability of the numerical solution, with the cubic spline interpolation of the catenary displacement, the velocity and acceleration constraints as well as the displacement constraint are imposed on the contact point. Through the various numerical examples, it is shown that the dropper positions as well as the static deflection are crucial to determine the contact and separation of the pantograph of a high-speed train.

A Basic Study of Catenary System Corresponding to Speed-Up of the Rail Way (전기철도 고속화에 대응한 가선구조에 대한 기초연구)

  • yang ung-chow;choi chang-kyu;chang sang-hoon
    • Proceedings of the KSR Conference
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    • pp.500-506
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    • 2003
  • Dopper should performance not only to constrain rolling and yawing system but also to develop capability of pantograph. In orde to get purpose, the survey and study that the type of dropper which convert 'I' type dropper into 'Y' type that performance to constrain rolling,yawing and jamping of catenary system simultaneously.

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A Study on Dynamic Characteristics of a Catenary System (가선계의 동특성에 관한 연구)

  • 김정수;최병두
    • Journal of KSNVE
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    • v.9 no.2
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    • pp.317-323
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    • 1999
  • Dynamic characteristics of catenary that supplies electrical power to high-speed trains are investigated. A simple catenary is composed of the contact and messenger wires connected by droppers possessing bi-directional stiffness properties. For slender, repeating structures such as catenary, both the wave propagation and vibration properties need to be understood. The influence of parameters that determine catenary dynamics are investiaged through numerical simulations involving finite element models. The effects of the tension and flexural rigidity of the contact wire is first investigated. The effects of dropper characteristics are then investigated. For linear droppers wave propagation as well as modal properties are determined. For large catenary motion, droppers can be modeled as bi-directional elements possessing low stiffness in compression and high stiffness in tension. For this case, impulse response is computed and compared with the cases of linear droppers. It is found that the catenary dynamics are primarily determined by contact wire tension and dropper properties, with large responses observed in 5∼40 Hz frequency range. In particular, the dropper stiffness and spacing are found to have dominant influence on the response frequency and the wave transmission characteristics.

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A Study on RCM Approach to Catenary System of Electric Railway (전기철도 가공전차선로의 신뢰성 기반 유지보수(RCM)에 관한 연구)

  • Youn, Eung-Kyu;Choi, Kyu-Hyoung
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.8
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    • pp.1457-1465
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    • 2016
  • A RCM approach to maintenance of the catenary system of electric railway is proposed. The proposed RCM approach provides a maintenance-oriented FMECA procedure to derive critical failure modes by analyzing failure effects and a RCM decision logic tree to suggest optimal maintenance works for the derived failure modes. By applying the proposed RCM procedures to the catenary system of high speed railway, it is suggested that strand breaks of dropper and voltage equalizing wire, and trolly wire wear-out are the critical failure modes for whom maintenance works based on condition monitoring should be applied instead of conventional time-based preventive maintenance. It is also proposed by reliability analysis that replacement time of dropper can be reduced from 18 years to 10 years. These results show that the proposed RCM approach can optimize the maintenance procedures of catenary system.

A Study on the Geometry Change for the Increased Contact Wire Tension in the Pre-sagged Existing Catenary (사전 이도가 주어진 기설 전차선로에서 전차선 장력을 증가시켰을 때 전차선 기하학적 형상 변화 연구)

  • An, Seung-Hwa;Kim, Yoon-Ho
    • Journal of the Korean Society for Railway
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    • v.15 no.5
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    • pp.447-453
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    • 2012
  • It is studied that the structure of the contact plane geometry of the contact wire would be changed when the contact wire tension is increased in the existing overhead contact lines for the purpose of improving the operation speed temporarily. In this paper, the dropper length formula which could be well applied to the pre-sagged catenary is reviewed first. Second, the changing amount of the pre-sag if the contact wire tension change from 20kN to 23kN or from 20kN to 25kN for the Gyeongbu HSL(high speed line) 49.5m catenary is evaluated by using of the self-written program in accordance with the dropper length formula. Moreover, the increasing tension and measuring the pre-sag change experiment in the Gyeongbu 2 HSL was conducted. The calculated data are compared with the measured data. As a result, it is found that the geometry change is very little and will not make the current collection performance deteriorated.

A Study on the 3D Digital Restoration Technology Using a Shard of a Joseon Dynasty White Porcelain Water Dropper (조선시대 백자 연적 편(片)을 활용한 3차원 디지털 복원 기술 연구)

  • Shin, Woocheol;Kim, Kyungjoong;Wi, Koangchul
    • Conservation Science in Museum
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    • v.22
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    • pp.85-96
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    • 2019
  • The restoration of ceramics excavated in fragments is limited by the difficulty of inferring the overall shape of the original object. However, recent innovations in digital technology can help to overcome the limits of conventional restoration using handwork. This study explored the potential of digital technology by digitally restoring a shard from a white porcelain water dropper excavated at a kiln site at Sindae-ri. In order to complete the digital restoration, 3D scanning was applied to obtain scan data, and 3D modeling and texture mapping were performed. In this way, three-dimensional data with patterns and color information was acquired and the original form of the water dropper could be ascertained based on the shard. The study found that the data acquired from digital restoration can be used for various purposes, including for obtaining data on cross-sections or missing portions of a relic.