• Title/Summary/Keyword: 부상량

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Study on Optimal Design of Traverse Switch System for Maglev Train (자기부상열차용 트레버스 분기기 최적설계 연구)

  • Lee, Younghak;Kim, Chang-Hyun;Lee, Jong-Min
    • Journal of the Korean Society for Railway
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    • v.19 no.6
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    • pp.717-726
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    • 2016
  • Emergency tracks are necessary in case a broken down train evacuates, a train needs to make way for a faster train behind it, or a train suddenly stops and following trains must avoid colliding with it. Magnetic Levitated (maglev) Trains can change track to enter an emergency track using a segmented switch or a traverse switch. On a traverse switch, a train can change its track when the part of the track that the train is on moves to the other track. Currently manufactured Maglev trains have two bodies and the total length is 25 meters. If a traverse switch is used, it will only require 30 meters of track to move the train to the other track, so, when it comes to efficiency of costs and space, the traverse switch surpasses the articulated switch. Therefore, in this paper, an optimized design to secure structural safety and weight lightening is suggested. To achieve these results, the heights of the piled concrete and girders which are both placed on the top of the traverse switch, are set as design variables. The Finite Element Method (FEM), in application of kriging and in the design of the experiments (DOE), is used. Maximum stress, deformation, and structural weight are compared with the results, and through this process structural safety and weight lightening is proven.

Study on Running Safety of EMS-Type Maglev Vehicle Traveling over a Switching System (상전도흡인식 도시형 자기부상열차의 분기기 주행안전성 연구)

  • Han, Jong-Boo;Lee, Jong Min;Han, Hyung-Suk;Kim, Sung-Soo;Yang, Seok-Jo;Kim, Ki-Jung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.11
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    • pp.1309-1315
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    • 2014
  • The switch for a maglev vehicle should be designed such that the vehicle safely changes its track without touching the guiderail. In particular, a medium-to-low-speed EMS -type maglev train relies heavily on a U-type electromagnet where it generates levitation force and guidance force simultaneously. Therefore, it is necessary to evaluate the safety of the vehicle whenever it passes the switch, as it lacks active control of the guidance force. Furthermore, when the vehicle passes a segmented switch, which is a group of curves made up of connected lines with a small radius of curvature, it may come into mechanical contact with the guiderail owing to the excessive lateral displacement of the electromagnet. The goal of this study is to analyze the influence of a segmented switch on the safety of major design-related variables for achieving improved running safety. We propose a three-dimensional multibody dynamics model composed of two cars with one body. Using the proposed model, we perform a simulation of the lateral air gap, which is one of the measurements of the running safety of the vehicle when it passes the switch. The analyzed design variables are the length between short span girder, the articulation angle, the length between two centers of a fixed girder at its ends, and the number of girders. On the basis of the effects of the considered design variables, we establish an optimized design of a switch with improved safety.

Development of the Small Scale Testbed for Running Dynamic Characteristics Analysis of the Capsule Train (캡슐트레인 주행 동특성 분석을 위한 축소 시험장치의 개발)

  • Lee, Jin-Ho;You, Won-Hee;Lee, Kwansup
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.9
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    • pp.643-651
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    • 2020
  • A capsule train runs inside a sub-vacuum tube and can reach very high speed due to the low air resistance. A capsule train uses a superconducting electrodynamic suspension (SC-EDS) method for levitation, which allows for a large levitation gap and does not require gap control. However, SC-EDS has inherent characteristics such as the large gap variation and a small damping effect in the levitation force, which can degrade the running stability and ride comfort. To overcome this, a stability improvement device should be designed and applied based on dynamic analysis. In this study, a 1/10 small-scale testbed was developed to replicate the dynamic characteristics of a capsule train and investigate the performance of stability improvement devices. The testbed is composed of a 6-degree-of-freedom Stewart platform for the realization of bogie motion, a secondary suspension with a running stabilization device, and a carbody. Based on the dynamic similarity law proposed by Jaschinski, the small-scale testbed was manufactured, and a bogie motion algorithm was applied with the consideration of guideway irregularity and levitation stiffness. The experimental results from the testbed were compared with simulation results to investigate the performance of the testbed.

Effect of lime types on growth and yield of soybean at newly reclaimed soil (신개간지토양(新開墾地土壤)에서 석회비종(石灰肥種)이 대두(大豆)의 생육(生育) 및 수량(收量)에 미치는 영향(影響))

  • Kim, Hee-Kweon;Jeon, Jang-Hyeob;Chung, Chi-Ho;Park, Keon-Ho
    • Korean Journal of Soil Science and Fertilizer
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    • v.22 no.1
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    • pp.39-44
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    • 1989
  • This experiment was conducted to mature newly reclaimed upland and to increase soybean yield at this upland, Kim Jae, Jeon Buk, Koera from 1987 to 1988. Lime, lime-magnesium and calcium sulfate were applied with two, levels, amount of lime requirement, and 1.5 times of lime requirement. The results were summarized as follows: 1. The yields of soybean among treaments were in order of lime-magnesium 1.5 times, lime 1.5 times, lime-magnesium, calcium sulfate, lime and control with significancy at 1% level. 2. Correlations between yield components and inorganic element contents (T-N, $P_2O_5$, CaO and MgO) in plant at flowering stage were positive, but manganese in plant was negative at 5%, respectively. 3. Correlations, between yields and MgO and CaO contents in plant at flowering stage were positive, but Mn in plant was negative at 5% respectively. 4. Inorganic element contents of the soils at flowering stage were higher than those of before experiment. Correlation between yield and base saturation degree in soil at flowering stage was positive at 5%.

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감소율 적용 방안 놓고 논란 '후끈'

  • Korea Electric Association
    • JOURNAL OF ELECTRICAL WORLD
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    • s.352
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    • pp.56-59
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    • 2006
  • 석탄, 석유 값의 지속적인 상승과 기후변화협약 발효 등 환경규제의 강화로 신 · 재생에너지에 대한 관심과 인기가 연일 올라가고 있다. 국내에서도 관련 업계의 신 · 재생에너지 사업에 대한 참여도가 매년 급증하고 있는 상황이다. 지난 2002년 신 · 재생에너지분야에서 생산한 총 발전량이 156.731MW에서 지난해에는 389.954MW로 2.4배나 늘었다. 이러한 급증세는 정부의 신 · 재생에너지 확대 정책에 따른 것이기도 하다. 정부는 여러 가지 지원제도를 통해 신 · 재생에너지의 활성화를 위해 노력하고 있다. 그 중 가장 효과가 큰 제도가 바로 2002년부터 시행 중인 '발전차액 지원 제도'이다. 사실 신 · 재생에너지는 초기 투자비가 높고 원가가 원자력 및 화석연료에 비해 2~10배가량 높다. 이러한 상황에서 발전차액을 지원해 주는 제도는 가히 매력적이라고 볼 수 있다. 그런데 최근 정부에서 이러한 '발전차액 지원제도'를 개선하겠다고 발표하면서 신 · 재생에너지 관련 시장을 후근 달아오르게 하고 있다. 그 이유는 바로 정부가 발전차액 지원 금액을 줄이겠다고 발표했기 때문. 따라서 관련업계에서는 당연히 반발할 수 밖에 없다. 그러나 정부 측 주장대로 그동안 기술적인 발전과 발전량의 증가 등으로 인해 이 시점에서 한 번 제도를 개선할 필요성도 있다. 최근 '뜨거운 감자'로 부상한 '발전차액 지원제도 개선안'의 내용과 논란 내용을 소개한다.

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Plasma and Liver Cholesterol Lowering Substances in Gyrophora Esculenta (Sogi) I. Effects of Gyrophora esculenta (Sogi) on the plasma and liver cholesterol in rats (석이(石茸)버섯 (Gyrophora eseulanta) 중(中)에 함유(含有)되여있는 간장(肝臟) 및 혈장(血漿)콜레스테롤의 저하(低下) 생리활성물질(生理活性物質)에 관(關)한 연구(硏究) -제(第) 1 보(報)- 식이버섯이 흰쥐의 헐장과 간 콜레스테롤에 미치는 효과)

  • Kim, Chon-Ho;Fukuba, Hiroyasu
    • Journal of Nutrition and Health
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    • v.16 no.1
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    • pp.27-33
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    • 1983
  • Sprague-Dawley계(系) 숫놈 흰쥐에게 석이버섯 분말을 사료에 첨가 (0.5%, 1.0%, 3.0%, 5.0%, (群)) 하여 6주간 사육한후 혈장 및 간장중에 콜레스테롤의 변화(變化)를 측정(測定)한 결과 다음과 같다. 1) 석이버섯 분말 첨가군에 있어 기본식이군이나 대조군에 비하여 체중증가나 사료섭취량에 특별한 차이나 영향을 나타내지 않았다. 2) 그러나 혈장 및 간장지질량, 혈장 및 간장콜레스테롤치에 있어서는 현저하게 저하했음을 보였다. 3) 이러한 저하(低下)는 첨가량 증가에 따라 저하율이 뚜렸했으나 간지질량 측정에서 3.0% 첨가군이 가장 효과를 나타냈다.

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Design Criteria of the Median Barrier Considering Impulse Measurement (충격량을 고려한 중앙분리대 설계기준에 관한 연구)

  • Park, Je-Jin
    • Journal of Korean Society of Transportation
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    • v.26 no.2
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    • pp.167-176
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    • 2008
  • Although a rate of car accident death is on the decrease, internal rate of median encroachment accident is still high. In order to reduce the median encroachment accident, government use median barriers but there are no exact criteria of them. Particularly, current impulse measurement method has adopted the uniformly operating speed and encroachment angle. At reality, however, there are various conditions depends on driver's characters. In that reason, this study calculates reasonable impulse quantity through encroachment angle and operating speed. It will be necessary to prevent overuse treasury and car accidents.

Study of the Capsule Train Ride Comfort Improvement by using the Damping Control in Suspension System (현가장치 내 감쇠 제어를 이용한 캡슐트레인 승차감 향상 연구)

  • Lee, Jin-Ho;Lim, Jungyoul;You, Won-Hee;Lee, Kwansup
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.10
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    • pp.547-557
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    • 2020
  • In this study, damping control devices were applied to the suspension system of a capsule train, and the effects were investigated to improve the ride comfort. The superconductor electrodynamic suspension (SC-EDS) method is used for the capsule train levitation. This method has advantages such as no gap control and a large gap. However, the SC-EDS method has disadvantages such as large gap variation and small damping characteristics against outer vibration, which causes degradation of the ride comfort. In this study, the damping control devices in the primary and secondary suspension were considered to improve the ride comfort in the capsule train. Damping control devices in the primary and secondary suspension can reduce the vibration transmission from outer disturbances to the bogie and from the bogie to the car body, respectively. Simulations for dynamic characteristics analyses were conducted based on the capsule train dynamic model to investigate the effects of the damping control devices on the ride comfort. As a result, it was confirmed that the ride comfort requirements according to the ISO standard can be satisfied by applying the damping control in the capsule train suspension.

Parameter Analysis for Design of Pretension Girder Bridge for Urban Maglev Transit (도시형 자기부상열차 프리텐션 거더교의 설계변수 분석)

  • Lee, Jae-Ho;Kim, Do-Hak;Kim, Seung-Hyun;Kim, Sung-Il
    • Journal of the Korean Society for Railway
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    • v.19 no.4
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    • pp.515-525
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    • 2016
  • Parameter analysis of a pretension girder bridge for urban maglev transit was performed to identify the main design parameters and their effect. Girder deflection at mid-span is the most important design criteria of urban maglev transit. Therefore, concrete compressive strength, girder height, girder length, and unbonded tendon length were selected as the design parameters that relate to girder deflection. In addition, tendon layout and unbonded tendon ratios were also considered as design parameters to control the top stress of the pretension girder section at the support. The analysis results show that both the girder height and length are dominant design parameters governing girder deflection, more important than compressive strength and unbounded tendon length. And, sensitivity analysis makes this study suggest design weight value. In terms of stress, a tendon layout that can satisfy the unbounded tendon rule requires an additional tendon or rebar at the upper section to control the tensile stress on top of the section. Therefore, to improve feasibility and constructability in the future, an enhanced unbonded tendon rule considering the load characteristics of the urban maglev system should be studied.

Application of Lumley's Drag Reduction Model to Two-Phase Gas-Particle Flow in a Pipe(I) - Mechanism of Momentum Transfer- (고체분말이 부상하는 2상 난류 수직관 유동에 대한 Lumley의 저항감소 모델의 적용(I) - 운동량 전달 기구)

  • 한기수;정명균;성형진
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.13 no.6
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    • pp.1301-1309
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    • 1989
  • 본 연구의 목적은 Lumley의 저항감소 모델을 사용하여 여러 부하도하에서 부유유동의 유동 특성을 관찰하는 것으로, 특히 저항감소가 일어날 때와 일어나지 않을 때의 유동특성을 알아 보고자 한다.