• Title/Summary/Keyword: High-speed growth

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Reliability Growth Analysis for Next-Generation High-speed Train (차세대 고속열차의 신뢰성 성장 분석)

  • Noh, Hee-Min;Kim, Seog-Won
    • Journal of the Korean Society for Railway
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    • v.18 no.3
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    • pp.186-193
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    • 2015
  • In this paper, a reliability growth analysis for a next-generation high-speed train was conducted. First, the high-speed train was decomposed into 6 sub-systems and main equipment of the high-speed train was derived from functional diagrams. Next, failure rates were calculated for each sub-system from the failure data obtained during commissioning tests. Then, reliability growth analysis was conducted for the high-speed train using the Duane model. The results show that activities to increase reliability were carried out throughout the test runs from the reliability growth results.

Fatigue Crack Growth and Fracture behavior of Rail Steels

  • Seo, Jung Won;Kwon, Seok Jin;Lee, Dong Hyeong;Kwon, Sung Tae;Choi, Ha Yong
    • International Journal of Railway
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    • v.5 no.3
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    • pp.129-134
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    • 2012
  • Contact fatigue damages on the rail surface, such as head checks and squats are a growing problem. The fatigue cracks forming on the contact surface grow according to load and lubricating conditions and may end up breaking the rail. Rail fracture can be avoided by preventing the cracks from reaching the critical length. Therefore, the crack growth rate needs to be estimated precisely according to the conditions of the track and load to develop a maintenance plan against rail damages. Therefore, it is important to understand the mechanism of cracks initiation and growth on a rail due to repetitive rolling contact. In this study, we have investigated the crack growth behavior on the rail surface by using the twin-disc tests and the finite element analysis.

Effects of Swirl on Flame Development and Late Combustion Characteristic in a High Speed Single-Shot Visualized SI Engine (고속 단발 가시화 스파크 점화 엔진에서의 연소 특성에 대한 선회효과 연구)

  • Kim, S.S.;Kim, S.S.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.3 no.1
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    • pp.54-64
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    • 1995
  • The effects of swirl on early flame development and late combustion characteristic were investigated using a high speed single-shot visualized 51 engine. LDV measurements were performed to get better understanding of the flow field in this combustion chamber. Spark plugs were located at half radius (R/2) and central location of bore. High speed schlieren photographs at 20,000 frames/sec were taken to visualize the detailed formation and development of the flame kernel with cylinder pressure measurements. This study showed that high swirl gave favorable effects on combustion-related performances in terms of the maximum cylinder pressure and flame growth rate regardless of spark position. However, at R/2 ignition the low swirl shown desirable effects at low engine speed gave worse performances as engine speed increased than without swirl. There were distinct signs of slow-down in flame growth during the period when the flame front expanded from 2.5mm in radius until it reached 5.0mm apparently due to the presence of ground electrode. There seemed to be heat transfer effect on the flame expansion speed which was evidenced in high swirl case by the slowdown of the late flame front presumably caused by relatively large heat loss from burned gas to wall compared with low- or no-swirl cases.

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A Suggestion of New R&D Strategy based on an Analysis on a Trend of Evolution of World Wide High-Speed Rail Technology (최근 세계 고속철도 기술의 진화경향 분석을 통한 한국 고속철도의 향후 기술개발 전략)

  • Kim, Ki-Hwan;Mok, On-Yong
    • Proceedings of the KSR Conference
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    • 2009.05b
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    • pp.165-170
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    • 2009
  • The Korean high-speed rail network has been made a remarkable growth recording the world's 4th rank passenger transportation scale during last 5 years after opening the revenue service of Kyoung-bu high-speed line in 2004. However, in spite of it's outstanding growth, Korean Rail technology should meet a demand of intensive technology development in order to prepare a severe competition with an advance parties of worldwide high-speed rail technology. In this paper, the characteristics and new trend of world's rail industry was reviewed based on the most recent statistics and papers of worldwide rail network from UIC and WCR32008. In conclusion, new R&D strategy with choice an concentration for the Korean high-speed rail industry was suggested based on an analysis on the trend of evolution of the state of the art technologies in worldwide high-speed rail system.

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A progressive course of the Next Generation High-Speed Rail Development Project (차세대 고속철도기술개발사업 추진방향)

  • Kim, Ki-Hwan;Park, Chan-Kyoung;Kim, Suk-Won
    • Proceedings of the KSR Conference
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    • 2006.11b
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    • pp.1228-1233
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    • 2006
  • Since 1996, the G7 R&D and High-Speed Rail development project have been accomplished and it will be completed in 2007. During that time, we have achieved the origin design technique based on technique development experience. However, in order to magnify and to promote the growth of the origin design technique for railway industry to be a growth motive industry in future from intensive speed elevation and new technique competition of advanced nations, we need to prepare the next generation high-speed rail technique and to sustain expansion of the technique with getting hold of new technique tendency of the world. Therefore, this paper make research into necessity of the next generation high-speed rail development project, making an analysis of foreign countries cases and forward plan.

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Single Crystal Growth of $LiNbO_3$ ($LiNbO_3$의 단결정 성장)

  • 최종건;오근호
    • Journal of the Korean Ceramic Society
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    • v.22 no.5
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    • pp.43-46
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    • 1985
  • Constitutional supercooling due to concentration gradient at solid-liquid interface in the melt can be avioded by increasing rotational speed for growing $LiNbO_3$ single crystals from the stoichiometric melt. Growth conditions for high quality crystals were determined by rotational speed by which other growth parameters were adjusted.

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Experimental evaluation technique for condition monitoring of high speed machining (고속가공의 상태 감시를 위한 실험적 평가 기술)

  • 김전하;강명창;김정석;김기태
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.84-87
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    • 2001
  • The high speed machining which cam improve the production and quality has been remarkable in die/mold industry with the growth of parts and materials industries. The speed of machine tool increases, but on the other hand, the response of sensors I not being improved. Therefore, the condition monitoring techniques for the machine too, tool and workpiece in high speed machining are incomplete. In this study, characteristics of the tool edge roughness were verified from the high frequency components of cutting force signals acquired by the high speed dynamometer. Also, the experimental evaluation technique for the machinability and condition monitoring in high speed machining was established by analyzing the cutting force, acceleration and surface roughness.

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Signal Characteristics of Measuring System for Condition Monitoring in High Speed Machining (고속가공에서 상태 감시를 위한 계측시스템의 신호특성)

  • Kim, Jeong-Suk;Kang, Myung-Chang;Kim, Jeon-Ha;Jung, Youn-Shick;Lee, Jong-Hwan
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.2 no.3
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    • pp.13-19
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    • 2003
  • The high speed machining technology has been improved remarkably in die/mold industry with the growth of parts and materials industries. Though the spindle speed of machine tool increases, the condition monitoring techniques of the machine tool, tool and workpiece in high speed machining ate incomplete. In tins study, efficient sensing technology in high speed machining is suggested by observing the characteristics of cutting force, gap sensor and accelerometer signal also, machinability of high-speed machining is experimentally evaluated sensing technique to monitor the machine tool and machining conditions was performed.

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An Experimental Study on Bubbles Growth on Microheater (마이크로 히터에서의 기포 생성에 관한 실험적 연구)

  • Ko, Seung-Hyun;Kim, Shin-Kyu;Kim, Ho-Young;Jang, Young-Soo;Lee, Yoon-Pyo
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.1909-1914
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    • 2003
  • Bubble growth on microheater has been experimentally investigated in this study. The experiment was performed using platinum micro heaters having dimensions of $100{\times}10{\times}0.2{\mu}m^3$ with constant heat flux. A high speed video camera was used to observe bubble growth at 250 frames per second. Microheater temperature was measured at the rate of 300Hz with a data acquisition system. When heater temperature was $139^{\circ}C$ a bubble was nucleated in the liquid FC-72. The temperature profiles and the high speed camera images were combined to explain heat transfer and bubble growth on microheater.

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A Study of Pseudomonas putida Fed-batch Culture (Pseudomonas putida의 유가배양연구)

  • 김인호;김희정;송재양
    • KSBB Journal
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    • v.17 no.3
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    • pp.307-310
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    • 2002
  • In order to obtain high density seed cells for biofiltration, we studied batch and fed-batch culture of P. putida. Studies were carried out to find optimum fermentation conditions such as pH, concentration of glucose and agitation speed. Specific growth rate of P. putida was dependent on agitation speed and a high rpm of 300 was necessary to carry out the efficient aerobic growth of P. putida. Specific growth rate was highest at pH 7. Feeding glucose and yeast extract continuously at the initial growth phase was the most effective way to get high cell density of P. putida.