• Title/Summary/Keyword: maximum traction

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Traction Performance Improvement Study on a Small-scale Tower Yarder Attached to a Farm Tractor (농업용 트랙터 기반 소형 타워야더의 견인 성능 개선에 관한 연구)

  • Paik, Seung Ho;Choi, Yun-Sung;Cho, Min-Jae;Mun, Ho-Seong;Han, Sang-Kyun;Kim, Dae-Hyun;Oh, Jae-Heun
    • Journal of Korean Society of Forest Science
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    • v.108 no.4
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    • pp.562-573
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    • 2019
  • In a cable yarding system, a small-scale tower yarder attached to a farm tractor wasdeveloped and used for small-diameter tree harvesting operations. Based on this design, improvement of traction performance was required for medium- and large-diameter tree harvesting operations. In this study, the mechanical transmission employed for the tower yarder was modified into ahydro-mechanical transmission system. Maximum traction forces, including tractor engine speed and hydraulic power pressure, were investigated, and comparisons were made between the mechanical and hydro-mechanical transmission systems. Six tractor engine speeds (1,200, 1,400, 1,600, 1,800, 2,000, and 2,200) and three levels of power transmission mechanism pressure (4.9, 6.9, and 8.8 MPa) were investigated in the two different transmission systems. Results showed a maximum traction force of 15,146.6 N at an engine rotation speed of 757 rpm in the current mechanical transmission system, and 36,140.0 N at anengine rotation speed of 1,575 rpm in the modified hydro-mechanical transmission system. The maximum traction forces for the hydro-mechanical transmission were 2.4 times greater than those of the mechanical transmission, and may therefore be applicable to medium and large-diameter tree harvesting operations. Thus,as a modified version of the conventional transmission system, the new hydro-mechanical transmission system may be cost-effective for use in large-scale cable yarding operations. In the future, however, it will be necessary to investigate problems that may arise from field application tests.

Calculation methods for the rail potential rise and the stray current in the ungrounded DC traction system (비접지 급전시스템에서의 레일전위상승과 누설전류 계산)

  • Chung, Sang-Gi;Park, Hyun-Joon;Kwon, Sam-Young;Bai, Chang-Han
    • Proceedings of the KSR Conference
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    • 2006.11b
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    • pp.631-635
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    • 2006
  • DC traction power system is operated ungrounded to minimize the stray current. This causes rail potential increase and makes hazardous condition to the person in touch with running rails. To prevent the hazardous condition, maximum allowable limits on rail potential rise are set by regulations in advanced foreign countries. In this paper, the simplified calculation methods for the rail potential rise and the stray currents are discussed.

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Prediction of Maneuverability and Efficiency for a Mobile Robot on Rough Terrain through the development of a Testbed for Analysis of Robot-terrain interaction (지형-로봇간의 상호작용 분석 장치의 개발을 통한 야지 주행 로봇의 기동성 및 효율성 예측)

  • Kim, Jayoung;Lee, Jihong
    • The Journal of Korea Robotics Society
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    • v.8 no.2
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    • pp.116-128
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    • 2013
  • This paper focuses on development of a testbed for analysis of robot-terrain interaction on rough terrain and also, through one wheel driving experiments using this testbed, prediction of maximum velocity and acceleration of UGV. Firstly, from the review regarding previous researches for terrain modeling, the main variables for measurement are determined. A testbed is developed to measure main variables related to robot-terrain interaction. Experiments are performed on three kinds of rough terrains (grass, gravel, and sand) and traction-slip curves are obtained using the data of the drawbar pull and slip ratio. Traction-slip curves are used to predict driving performance of UGV on rough terrain. Maximum velocity and acceleration of UGVs are predicted by the simple kinematics and dynamics model of two kinds of 4-wheel mobile robots. And also, driving efficiency of UGVs is predicted to reduce energy consumption while traversing rough terrains.

Power System Simulation in Seoul matropolitain subway Line-6 system (서울 지하철 6호선에 대한 전력계통 시뮬레이션)

  • Lee, Tae-Shik;Moon, Young-Hyun;Sung, Soo-Young;Yoon, Kap-Koo
    • Proceedings of the KIEE Conference
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    • 1993.07a
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    • pp.137-139
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    • 1993
  • This paper details methods used to verify the adquacy of a dc traction power supply for design in Seoul matropolitain subway Line-6 system. Examples of the approach are given for a major subway presently under construction. The performance of trains operating at maximum system design capacity is modelled using a train simulation program. Using a dc network analyser program, the maximum train operating timetable, and a model of the ac and dc electrical suppy system, the electrical performance of the entire system can be modelled over a 24-hour period. The results of this analysis are used to determime: train voltage at a level sufficient to ensure train schedules: adequacy of traction transformers, rectifier, and switchgear ratings; sizes of the overhead contact systern conductors, and ac and de feeder cables: and power and energy demands at the utility company's supply points for inital and final timetable operations.

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Thermoelastic Finite Element Analysis of Double horizontal Subsurface Cracks Due to Sliding Surface Traction (마찰열을 고려한 미끄럼 접촉시 내부 복수 수평균열 전파해석)

  • 이진영;김석삼;채영훈
    • Tribology and Lubricants
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    • v.18 no.3
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    • pp.219-227
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    • 2002
  • A linear elastic fracture mechanics analysis of double subsurface cracks propagation in a half-space subjected to moving thermomechanical surface traction was performed using the finite element method. The effect of frictional heat at the sliding surface on the crack growth behavior is analyzed in terms of the thermal load and peclet number. The crack propagation direction is predicted in light of the magnitudes of the maximum shear and tensile stress intensity factor ranges. When moving thermomechanical surface traction exists, subsurface horizontal cracks are propagation in-plane crack growth rate at the beginning but they are propagation out-of-plane crack growth rate by the frictional heat which is occurrence by the repeated sliding contact.

Frame Design Considering Exciting Frequency and Driving Characteristic of a Traction Motor for Electric Locomotive (전기기관차 견인전동기 운전점 특성과 가진주파수를 고려한 프레임 설계)

  • Kim, Chul-Su;Kim, Jae-Moon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.12
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    • pp.1759-1763
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    • 2014
  • In this paper, we were performed a structural analysis and durability analysis for an integral frame with an axle according to development of the electric locomotive traction motor. In terms of the structural stability, as a result of the analysis modeling with coupling conditions of beam element and an alternative element of three-dimensional, the maximum von-Mises stress of the locking screw mounting frame were similar as 50MPa and 51MPa. Also A comparison of the natural frequency and the exciting frequency while driving of the electric locomotive No. 8200, the natural frequency is 627.05Hz~856.9Hz while the exciting frequency is not more than most 30Hz or 553Hz, 1110Hz. Therefore, it is possible to avoid the resonance.

Analysis of Insulation Condition in Traction Motor Stator Windings (견인전동기 고정자 권선의 절연상태 분석)

  • Kim, Hee-Dong;Park, Young
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.20 no.7
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    • pp.631-635
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    • 2007
  • Diagnostic, surge and ac breakdown tests are widely used to evaluate the insulation condition of stator winding in traction motor. Diagnostic test included ac current, tan delta and maximum partial discharge. The result of diagnostic test indicates that five kinds of stator windings are good condition. Surge test was peformed to confirm the healthy of turn insulation in stator windings. This test is very easy to detect the turn insulation failure between normal and defect stator windings. After completing the diagnostic test, ac breakdown test has conducted gradually increasing ac voltage, until the stator winding punctured. No. 5 stator windings failed near rated voltage of 18.9 kV The breakdown voltage of No. 1 stator windings was 13.0 kV The ac breakdown voltage of normal winding is about 1.45 times higher than that of defect windings. The failure was located in a line-end coil at the exit from the core slot.

Thermoelastic Finite Element Analysis of Multiple horizontal Subsurface Cracks Due to Sliding Surface Traction (마찰열을 고려한 미끄럼 접촉시 내부 복수 수평균열 전파해석)

  • 이진영;김석삼
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2000.11a
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    • pp.50-58
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    • 2000
  • A linear elastic fracture mechanics analysis of multiful subsurface cracks propagation in a half-space subjected to moving thermomechanical surface traction was peformed using the finite element method. The effect of frictional heat at the sliding surface on the crack growth behavior is analyzed in terms of the thermal load and peclet number. The crack propagation direction is predicted in light of the magnitudes of the maximum shear and tensile stress intensity factor ranges. When moving thermomechanical surface traction exists, subsurface horizontal cracks are propagation in-plane crack growth rate at the beginning but they are propagation out-of-plane crack growth rate by the frictional heat which is occurrence by the repeated sliding contact.

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A New Overmodulation Strategy for Traction Dirve. (견인용 인버터를 위한 새로운 과변조 기법)

  • 배본호;설승기;김상훈;이인석;한성수
    • Proceedings of the KSR Conference
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    • 1998.11a
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    • pp.171-178
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    • 1998
  • This paper proposes a new overmodulation strategy to give a better voltage utilization by tracking voltage vector along hexagon sides. This strategy enables the inverter to control both magnitude and angle of current. Therefore, the vector control using this strategy can lead to better output torque dynamics compared to the conventional slip frequency control with six-step voltage, which is widely used in the traction drive. In this strategy, the d-axis output voltage of a current controller to control the flux is conserved and the q-axis output voltage to control the torque is controlled to place the voltage vector on the hexagon boundary In case of overmodulation. The limited q-axis voltage is used for anti-windup of q-axis current controller. This paper also presents a new field weakening scheme which incorporate the proposed overmodulation strategy. In this scheme, the flux level is selected by both required current limit and the available maximum voltage along hexagon sides. The validity of the proposed overall scheme is confirmed by the computer simulations for a typical traction drive with a 210[㎾] induction motor.

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Behavior of Composite Structure by Nonlinearity of Steel-concrete Interface(II) -Behavior of Steel-Concrete Interface- (강·콘크리트 경계면의 비선형성에 따른 합성구조체 거동 (II) -강·콘크리트 경계면의 거동 특성-)

  • Jeong, Youn Ju;Jung, Kwang Hoe;Kim, Byung Suk
    • Journal of Korean Society of Steel Construction
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    • v.15 no.5 s.66
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    • pp.509-518
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    • 2003
  • In this study, we carried out nonlinear analysis according to various interface nonlinear models by interaction magnitude, and analyzed interface behavior such as distribution of tangential traction and relative slip in steel-concrete composite structure. As a result of this study, tangential traction and relative slip of interface is rapidly increased at the steel plate-concrete interface, especially at the neutral region, rather than tensile, as opposed to the T beam-concrete interface. In transverse direction, it has gradually reduced to go outside from loading position. In longitudinal direction, it was minimum at the central region near the loading point, maximum at 0.6-0.7L from support and gradually reduced as it nears support. Moreover, as the load is increased, the failure of interface gradually expands from the maximum tangential traction position to the entire region. It is expected to provide fundamentality for interface behavior and load-carrying mechanism, and for the design of bending and shear connection of steel-concrete composite structure.