• Title, Summary, Keyword: Dropper

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Considerations in the reliability improvement against Circulation Current in the Catenary System for Electirc Railway of Korea (전차선로시스템의 순환전류에 대한 안정성 향상에 관한 고찰)

  • Kim, In-Cheol;Kang, Seung-Wook
    • Proceedings of the KIEE Conference
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    • pp.24-26
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    • 2006
  • In these days, Korea Railway apply simple catenary system to general lines and high speed lines of Korea Electric Railway. Circulation Current in catenary system frequently bring undesirable consequences. Namely, the Connector wire has many problems according to a flow of excessive circulation (or traction current) and a sudden rise of temperature on catenary when electric car or locomotive is running in high speed. The occurrence of events by the load increasement do considerable damages to peoples, organizations and systems. In this paper, we proposed the improved changes on the catenary system of a improvement and change of a messenger wire protector, improvement of connector wire,s institution angle and of a replacement the connector wire with a dropper. A case of Circulation Current continually has broken out in Yongdungpo Electric Office's own bailiwick. By or through the medium of these obstacles, we have further use of many studies and considering countermeasures. Therefore, we have to deal with the question in design and execution of catenary system for High Speed Railway because we will spend a lot of time and more money for maintenance than for construction of that.

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A study on better wire protector of equipment on the Circulating Current in Catenary System (순환전류에 대한 전철설비 보호카바 개선 연구)

  • Kang, Seung-Wook;Kim, In-Chol;Kim, Hyo-Jin;Kim, Dae-Sik;Baek, Seong-Hyun;Han, Sang-Ok
    • Proceedings of the KIEE Conference
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    • pp.375-378
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    • 2007
  • In these days, Korea Railway apply simple catenary system to general lines and high speed lines of Korea Electric Railway. Circulation Current in catenary system frequently bring undesirable consequences. Namely, the Connector wire has many problems according to a flow of excessive circulation (or traction current) and a sudden rise of temperature on catenary when electric car or locomotive is running in high speed. The occurrence of events by the load increasement do considerable damages to peoples, organizations and systems. On a case by case accidents, the reeltype protective cover as part of various methods has some problems. In this project, we proposed the improved changes on the catenary system of a improvement and change of a messenger wire protector, improvement of connector wire's institution angle and of a replacement the connector wire with a dropper. Its tridimensional space limitation dictated the scale of the $32{\times}{\Phi}55$ to be as small as possible. It is easier to install than work by the existing cover on the messenger wire.

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An Adaptive Drop Marker for Edge Routers in DiffServ Networks

  • Hur, Kyeong
    • Journal of information and communication convergence engineering
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    • v.9 no.4
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    • pp.411-419
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    • 2011
  • In this paper, we propose an Adaptive Regulating Drop (ARD) marker, as a novel dropping strategy at the ingressive edge router, to improve TCP fairness in assured services (ASs) without a decrease in the link utilization. To drop packets pertinently, the ARD marker adaptively changes a Temporary Permitted Rate (TPR) for aggregate TCP flows. The TPR is set larger than the current input IN packet rate of aggregate TCP flows while inversely proportional to the measured input OUT packet rate. To reduce the excessive use of greedy TCP flows by notifying droppings of their IN packets constantly to them without a decrease in the link utilization, the ARD marker performs random early fair remarking of their excessive IN packets to OUT packets at the aggregate flow level according to the TPR. In addition, an aggregate dropper is combined to drop some excessive IN packets fairly and constantly according to the TPR. Thus, the throughput of a TCP flow no more depends on only the sporadic and unfair OUT packet droppings at the RIO buffer in the core router. Then, the ARD marker regulates the packet transmission rate of each TCP flow to the contract rate by increasing TCP fairness, without a decrease in the link utilization.

The Development of the Observation Assessment Criteria concerning the Manipulative skills in Elementary School Science (초등학교 과학실험 기구 조작 기능에 대한 관찰 평가 준거 개발 - 초등학교 화학 단원을 중심으로 -)

  • 최행숙;백성혜
    • Journal of Korean Elementary Science Education
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    • v.18 no.1
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    • pp.65-73
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    • 1999
  • The purpose of this study is tile development of tile observation Assessment criteria that is used to assess manipulative skills in elementary science. The procedures of developing observation Assessment criteria are as follows. First, we investigated the actual condition about science process skills assessment with tile questionnaire. Second, we selected 7 experimental apparatus through the analysis of the science textbooks. The selected experimental apparatus are dropper, alcohol lamp, thermometer, test tube, filtering device, able balance, graduated cylinder Third, the observation Assessment criteria arc developed through tile analysis of the related experimental textbooks, the demonstrations, and the questionnaire, Forth, tile validity is verified by science education specialists and graduate students who major in science education. Fifth, the first jilter-rater agreement is investigated in the result of the field with observation criteria of which the validity was verified. The second inter-rater agreement is investigated through the revision and the addition of the criteria with the low agreement. In result, the jilter-rater agreement ranged from 0.86 to 0.98. One of the major problems in observation assessment is the rater's subjective viewpoint. So, this research shows a more specified scale and criteria for the assessment. This suggests that the observation Assessment criteria developed in tile study satisfies the high reliability and validity requirements. Considering the results, this criteria call be used effectively for assessing manipulative skills of elementary school students.

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A Study on Reliability Analysis of Electric Railway Catenary System using FMECA (FMECA를 통한 전차선로 가선시스템의 신뢰도 분석에 관한 연구)

  • Youn, Eung-Kyu;Choi, Kyu-Hyoung
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.11
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    • pp.1618-1625
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    • 2015
  • The reliability of catenary system is very important for uninterrupted train operation as it supplies electric power to train without redundant facilities. This paper provides a systematic approach to the reliability analysis of the catenary system based on FMECA procedures defined by global standards such as MIL Std 1692a and IEC 60812. Field failure data collected from the operation and maintenance of high-speed railway catenary system for 9 years are used to derive critical failure modes and to evaluate the criticality of the failure modes. Evaluation of the criticality are carried out by quantitative procedures defined by MIL Std 1692a and by criticality matrix defined by IEC 60812. FMECA results suggests that three critical failure modes should be checked carefully during maintenance work, which include strand break of dropper and voltage equalizing wire, power supply failure of feeder. Maintenance procedure of catenary system in order of importance is suggested too. These results can be applied to maintenance planning and design of catenary system to improve the reliability of electric railway system.

Development of a Steady Arm for the Maximum Speed of 400 km/h (400 km/h급 전차선로 곡선당김금구 개발)

  • Lee, Kiwon;Park, Young;Kwon, Sam-Young;Cho, Yong Hyeon;Jeong, Heonsoo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.12
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    • pp.1742-1746
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    • 2014
  • In order to develop a overhead catenary system for the maximum speed of 400 km/h on Honam high-speed line, increasing tension of contact wire, changing dropper distributions, reducing a hard point and etc. should be considered. And it is also essential to develop core components taking account of the increased tension. Therefore we developed a new steady arm for the max. speed of 400 km/h in this study. FEM (Finite Elements Method) analysis was performed to ensure the strength of the arm. An oval shape was applied to the arm, so that 25 % of strength was increased and 9 % of weight was decreased. And a type test according to the code KRSA-3012 was performed to ensure the performance. Fatigue test in KRRI (Korea Railroad Research Institute)'s test-bed was also performed to evaluate its performance. Some section of the Honam High-speed line was constructed with the developed steady arm.

Study on Power Line Coupler for Auxiliary Power to Overhead Line (철도 전차선의 보조전원을 위한 전력선 커플러 연구)

  • Lee, Gunbok;Yi, Kyung-Pyo;Kim, Myung Yong;Lee, Su Gil;Chang, Sang Hoon
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.29 no.7
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    • pp.566-569
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    • 2018
  • A power line coupler that can apply high-frequency power to a railway overhead line structure was analyzed. It is difficult to supply auxiliary power to an overhead line in a high-voltage environment, and doing so requires a long-distance transfer. A method is proposed that utilizes the resonance on the Rogowski coil, which does not use a magnetic core. A simple overhead line structure was fabricated that consisted of a contact wire, messenger wire, and dropper. Couplers of various sizes were fabricated and deployed on the messenger wire, and the transfer characteristics of the two couplers were compared at a distance. As a result of applying the matching circuit to the coupler, the transmission efficiency was 53% at a distance of 2.5 m. The proposed method shows that it is possible to apply the auxiliary power by using the existing conductor in a special structure, such as the overhead line.

A Study on the quantitative Evaluation of Spasticity Implementing Pendulum Test (진자실험을 통한 경직의 정량적 평가에 관한 연구)

  • Lim H.K.;Cho K.H.;Kim B.O.;Chae J.M.;Lee Y.S.
    • Journal of Biomedical Engineering Research
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    • v.21 no.3
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    • pp.303-309
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    • 2000
  • An accurate quantitative biomechanical evaluation for the spasticity caused by the disorder of central nervous system was made in this study. A sudden leg dropper was designed to generate objective testing environment at every trial. 3-dimensional motion analysis system(Elite. B.T.S. Italy) was used to measure kinematic data which were angle. and angular velocity of a lower limb. A program was developed to analyze the kinematic data of lower limb motion. and dynamic EMG data at the same time. To evaluate spasticity quantitatively. total 26 parameters including 14 parameters newly driven were analyzed, and statistical analysis were made for bilateral correlations. Results showed possibility to make accurate quantitative and objective evaluation for spasticity with various new parameters using new devices and program.

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Adaptive Rate Control for Guaranteeing the Delay Bounds of Streaming Service (스트리밍 서비스의 지연한계 보장을 위한 적응적 전송률 제어기법)

  • Koo, Ja-Hon;Chung, Kwang-Sue
    • Journal of KIISE:Information Networking
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    • v.37 no.6
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    • pp.483-488
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    • 2010
  • Due to the prevalence of various mobile devices and wireless broadband networks, there has been a significant increase in interest and demand for multimedia streaming services. Moreover, the user can service the participatory video broadcasting service in the mobile device and it can be used to deliver the real-time news and more variety information in the user side. Live multimedia service of user participation should consider not only the video quality but also the delay bounds and continuity of video playback for improving the user perceived QoS (Quality of Service) of streaming service. In this paper, we propose an adaptive rate control scheme, called DeBuG (Delay Bounds Guaranteed), to guarantee the delay bounds and continuity of video playback for the real-time streaming in mobile devices. In order to provide those, the proposed scheme has a quality adaptation function based on the transmission buffer status and network status awareness. It also has a selective frame dropper, which is based on the media priority, before the transmission video frames. The simulation results demonstrate the effectiveness of our proposed scheme.

Elementary Students사, and Pre-service and In-service Elementary School Teachers사 Understanding on the Name and use. of Labware (초등학교 학생ㆍ예비 교사ㆍ현직 교사의 실험 기구 명칭과 용도에 대한 이해)

  • 여상인;이병문
    • Journal of Korean Elementary Science Education
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    • v.23 no.1
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    • pp.44-49
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    • 2004
  • This study was based upon the survey on the name of 13 basic experimental instruments used in elementary science class: Schale, evaporating dish, mortar & pestle, beaker, erlenmeyer flask, spuit(medicine dropper), graduated cylinder, balance, spatula, dropping bottle, gas collecting bottle, funnel, alcohol burner, and their uses. To implement this study, an open-ended, written questionnaire was administered to the subjects of in-service elementary school teachers, future elementary teachers who have attended at the Gyeongin national university of education, and elementary students in Korea. The findings of this study were as follows: The rates of in-service and pre-service elementary school teachers that knew correct name of experimental instruments were not high, the elementary school student's rates were especially very low. In this study, we found several reasons which they wrote inaccurately: the name to be represented at the textbook that they had studied, the confusion of the name about a fortis pronunciation, the recognition as the vocabulary like flask and cylinder to be meaningless, the habit to say in an everyday life, wrong expression in the internet and general book. All respondents had a wide range of perceptions of uses for the experimental instruments. Their understanding of uses for evaporating dish, erlenmeyer flask, balance, gas collecting bottle were very poor. And then most of them understood that graduated cylinder, beaker, and erlenmeyer flask were tools to measure the volume of solution or liquid, so they did not exactly distinguish the difference of their uses.

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