• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.425-431
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• 1999

Nowadays development of electric and optical devices needs precision more and more. This study focuses on hydrostatic journal bearing of grinding wheel spindle. It presents theoretical analysis about cylinder type self-controlled restrictor to control flux of oil flowing into pockets around the hydrostatic journal bearing. As a result of this analysis, optimal properties to maximize bearing stiffness such as initial cross distance, supply pressure, diameter of two supply holes, pre-load of spring and clearance between spindle and housing can be obtained. Therefore, by using them it is possible to estimate bearing stiffness and the performance of grinding wheel spindle can be improved.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.10
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• pp.875-882
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• 2011

In this paper, the finite element analysis model of the mult-axial wheel durability test configuration is created using SAMCEF. Mooney-Rivlin 2nd model is applied to the tire model, and the variation of the air pressure inside the tire is considered. Vertical load, lateral load and camber angle are applied to the simulation model. The tire rotates because of the friction contact with a drum, and reaches its maximum speed of 60 km/h. The dynamics stress results of the simulation and experiment are compared, and the reliability of the simulation model is verified.

• Transactions of Materials Processing
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• v.8 no.5
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• pp.498-506
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• 1999

The metal forming processes of aluminum alloy wheel forging at elevated temperature are analyzed by the finite element method. A coupled thermo-mechanical model for analysis of plastic deformation and geat transfer is adapted in the finite element formulation. In order to consider the strain-rate effects on material properties and the flow stress dependence on temperatures, rigid-viscoplasticity is introduced in this formation. In this paper, several process conditions were applied to the dimulation such as die speed, rib thickness, and depth of die cavity. Simulation results are compared, and discussed with each case. Metal flow, die pressure distributions, temperature distributions, velocity fields and forging loads are summarized as basic data for process design and selection of a proper press equipment.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.88-93
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• 2005

Frictional heat generates when the brake shoes are in contact with wheel tread under high pressure for EMU's speed control, stopping, and deceleration. Such a frictional heat has a significant effect on the wheel tread. In order to analyze the characteristics of frictional heat and measure the amount of the generated heat, tests by using a brake dynamometer and for running vehicles are carried out. In addition, finite element analysis is performed to simulate the temperature distribution and thermal analysis of the brake shoes. Through the tests and the simulations, it is found that the problems by temperature increase at tread braking are verified.

• Proceedings of the KAIS Fall Conference
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• 2001.05a
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• pp.224-228
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• 2001

자동차용 Al Wheel의 반복 금형 주조 공정에 있어서의 적정 냉각조건 확립 및 수축공 등의 주조결함을 제어하기 위하여 3차원 응고, 유동, 응력 해석 프로그램 연동 기술과 자동 금형온도 조절장치를 실제 현장에 적용하여 생산되는 Al Wheel 제품의 최적 주조조건 및 냉각조건을 확립하였다. 주조과정 중의 금형의 온도 변화 및 주물의 응고, 유동 거동은 수치해석 결과와 잘 일치하는 경향을 나타내었다. 또한 금형온도 자동 조절 장치를 사용함으로서 금형 작업온도의 가열 및 유지가 정량적으로 제어 가능하며, 제품 품질의 유지 및 Cycle Time 최적화를 이룰 수 있으며 궁극적으로는 금형 수명 연장 및 생산성 향상 등을 이룰 수 있었다.

• Structural Engineering and Mechanics
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• v.53 no.5
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• pp.1051-1066
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• 2015

The study aims on the effect of material dependency in elastic- plastic contact models by contact analysis of sphere and flat contact model and wheel rail contact model by considering the material properties without friction. The various materials are selected for the analysis based on Young's modulus and yield strength ratio (E/Y). The simulation software 'ANSYS' is employed for this study. The sphere and flat contact model is considered as a flattening model, the stress and strain for different materials are estimated. The simulation of wheel-rail contact model is also performed and the results are compared with the flattening model. The comparative study has also been extended for finding out the mean contact pressure for different materials the E/Y values between 150 and 660. The results show that the elastic-plastic contact analysis for materials up to E/Y=296.6 is depend on the nature of material properties and also for this material the mean contact pressure to yield strength reaches 2.65.

• Journal of Korea Foundry Society
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• v.30 no.1
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• pp.46-51
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• 2010

Recently, automotive industry is attempting to replace steels for automotive parts with light-weight alloys such as aluminum alloy, because of the growing environmental regulations governing exhaust gas and the engine effectiveness of a vehicle. The low cycle fatigue (LCF) and high cycle fatigue (HCF) properties as well as the microstructure and tensile property were investigated on the low pressure cast A356 aluminum alloy wheel, which was followed by T6 heat treatment. The cast microstructure of the alloy influenced significantly on the low cycle and high cycle fatigue behaviors. The rim part of cast aluminum alloy wheel showed higher low cycle and high cycle fatigue strength compared with the spoke part, which should be caused by higher cooling rate of rim part. The spoke part of the wheel showed coarser dendrite arm spacing (DAS) and wide eutectic zone in the microstructure, which resulted in the partial brittle fracture and lower fatigue life time.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.4
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• pp.30-37
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• 2017

Weight reduction of the wheel is exerts a great influence on the running performance of the vehicle, a lot of research for a lightweight aluminum wheels progress. In order to select the molding conditions through the experiment on the carbon fiber prepreg molding process based on the design of the mold for manufacturing the carbon wheel using the carbon fiber pressure forming method, the carbon wheel molding process using the Taguchi method And to produce prototypes based on the results.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.5
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• pp.572-577
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• 2011

Curve squealing of inter-city railway vehicle is a noise with high acoustic pressure and rather narrow frequency spectra. This noise turns out to be very annoying for the people living in the neighborhood of locations and the passenger in railway vehicle where this phenomenon occurs. Squealing is caused by a self-exited stick-slip oscillation in the wheel-rail contact. Curve squeal noise of railway vehicles that passed by a factor of the speed limit, so to overcome in order to improve running performance is one of the largest technology. In the present paper, characteristic of squeal noise behavior at the Hanvit-200 tilting train test-site. Curve squealing of railway wheels/rail contact occurs in R400~ R800 curves with a frequency range of about 4~11 kHz. If the curve is less than the radius of wheel frail contact due to |left-right| noise level difference (dBA) shows a significant effect of squeal noise were more likely.

• Journal of the Korean Society for Railway
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• v.14 no.3
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• pp.234-239
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• 2011

Installing the temporary bridge after excavating the railway requires installing movable cross beam, but as it doesn't requires isolating the catenary or cutting the rail, it's applicable to double-track with frequent operation. In this study, a displacement meter was placed on temporary bridge to monitor the displacement pattern in curve section (R400) completed using temporary bridge method, and wheel load, lateral pressure and derailment coefficient were measured to evaluate the load imposed on track and the stability in curve section (R400) for quantitative evaluation of training running safety. As a result of the measurement, when trains passing over a temporary bridge, the maximum value of Wheel load and Lateral Force is analyzed as the 51% and 81% of standard level according to foreign country's performance tests, There is no trouble with stability analysis in Wheel load and Lateral Force occurring. Additionally, Wheel load and Lateral Force considered as the safety standard are tested 49% of limiting value regardless of trains, which the norm value quite well, there is no problem with train running.