• 한국자동차공학회논문집
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• 제9권3호
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• pp.221-229
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• 2001

The mechanical stress due to the wheel-rail contact and thermal stress due to the drag braking increase the incidence of wheel failure. So, firstly, stress analyses(mechanical, thermal and combined stress) of wheel plate are performed using 3-dimensional finite element method(FEM). Secondly, the optimum design of wheel plate ;s investigated in order to reduce weight of the wheel based on results of stress analysis. The optimum design is peformed using 2-dimensional axisymmetric F.E. model and its results are verified by 3-dimensional F. E. model.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.351-356
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• 2000

The mechanical stress due to the wheel-rail contact and thermal stress due to the drag braking increase the incidence of wheel failure. So, firstly, stress analyses(mechanical, thermal and combined stress) of wheel plate are performed using 3-dimensional finite element method(FEM). Secondly, the optimum design of wheel plate is investigated in order to reduce weight of the wheel based on results of stress analysis. The optimum design is peformed using 2-dimensional axisymmetric F.E. model and its results are verified by 3-dimensional F. E. model.

• Journal of Biosystems Engineering
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• 제9권2호
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• pp.19-26
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• 1984

This study intended to develop the prediction models of the traction and field performance of two-wheel tractors by using the principles which were applied for predicting those of the four-wheel tractors. The traction model developed in this study consists of the net traction coefficient, rolling resistance coefficient and traction efficiency, Which are expressed as functions of both wheel numeric and slip. A computer program on the field performance of two-wheel tractors is also developed to predict the drawbar horsepower, traction force, traction efficiency, rotational speed of engine and engine horsepower if the characteristics of the engine performance and operational condition of the two-wheel tractor are known. Based on the developed models, the conditions of basic variables to maximize the field performance were analyzed so as to assess the existing two-wheel tractor.

• 대한기계학회논문집A
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• 제33권10호
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• pp.1099-1107
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• 2009

Numerical simulation and experimental study to evaluate the critical speed of the railway bogie according to the tread inclination of wheel profile were conducted using 1/5 scale model. It has been shown that the results of the critical speed analysis for the scale bogie model is very close to the test results using scale bogie model and the critical speed is decreased in proportion to the increase of equivalent conicity of wheel profile. Results of this study show that the scale model could be applied to research area relating to vehicle stability as an alternative to overcome the experimental problems caused by full scale test on the roller rig.

• 한국철도학회논문집
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• 제5권2호
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• pp.118-124
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• 2002

The failure probability of wheel beyond 10$\^$7/ cycles is achieved by the strengths-stress interference model for the evaluation of fatigue strength and reliability in the wheel, From plane bending fatigue test results, the fatigue life (N$\_$f/) for the smooth and 200㎛ holed specimens can be represented as $\sigma$$\_$a/ = 1326N$\_$f/$\^$-0.10/ and $\sigma$$\_$a/ = 2894N$\_$f/$\^$-0.18/. Respectively, fatigue strength of the wheel at beyond 10$\^$7/cycles was about 332 MPa. And, the fatigue strength for the specimen with a micro hole (d=200㎛) which simulated an inclusion on the wheel surface was about 235 MPa. Thus, a micro hole (d=200㎛) caused about 30% reduction of fatigue strength of the specimen. The failure probabilities for the smooth and micro-holed specimens, derived from the strength-stress interference model, are 0.0148% and 13.05%, respectively. The current finding suggests that at least 200 ㎛ sized inclusion, which might be produced during manufacturing process, will cause a critical effect on integrity of the railway vehicle.

• Tribology and Lubricants
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• 제19권4호
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• pp.187-194
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• 2003

This paper describes the characteristics of wheel wear of high speed train running on the conventional line. Conventional line has many curved tracks that cause severe wheel flange wear. The influences of lubrication, cant deficiency, curve radius on wheel wear are also described considering the operation performance of the highspeed trainset. A method of calculation using contact patch work model is presented for determination of the evolution by wear of railway wheels.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.56.5-56
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• 2001

In the three axis control of satellite by using reaction wheel and gyro, a reaction wheel produces the control torque by the wheel speed or momentum, and a gyro carries out measuring of the attitude angle and the attitude angular velocity In this study, dynamic modelling of the Low Earth Orbit (LEO) is consisted of the one from the rotational motion of the satellite with the basic rigid body and a flexible body model, and the gyro in addition to the reaction wheel model. The results obtained by the robust controller are compared with those of the PI (Proportional and Integration) controller which is commonly used for the stabilizing satellite.

• 대한기계학회논문집A
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• 제37권2호
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• pp.177-185
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• 2013

본 논문에서는 윤중감소를 고려한 이론적 새로운 탈선계수 모델을 제시한다. 본 탈선계수 모델은 열차 충돌 원인 탈선현상을 예측할 수 있는 단일 윤축의 이론적 탈선모델을 바탕으로 도출한다. 현재 국내 탈선규정에서는 플랜지 각이 $60^{\circ}$ 이고 마찰계수가 0.3인 조건을 나달식에 적용하여 탈선계수를 구한 후 안전율을 적용하여 0.8을 규정하고 있으나, 플랜지 각이 변경되면 이론적 설명이 부족하게 된다. 따라서 제시한 탈선계수 이론모델을 이용하여 탈선계수 규정 값 0.8을 이론적으로 접근해본다. 또한 국내탈선규정에서 윤중 감소율을 50%까지 허용하고 있으나 명확한 규정근거를 제시하고 있지 않다. 따라서 윤중 규정 50%감소와 탈선계수 규정 값 0.8과의 상관 관계를 앞서 제시한 탈선계수 이론모델을 이용하여 이론적으로 규명한다. 마지막으로 동역학 시뮬레이션을 이용하여 탈선계수 이론모델의 타당성을 입증한다.

• Journal of Biosystems Engineering
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• 제13권4호
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• pp.1-8
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• 1988

A series of soil bin experiments was carried out on land to evaluate the soil physical properties whether they are pertinent to soil-wheel system and to investigate if true model theory u applicable to powered rigid wheel-soil system. Four different sized wheels having diameter of 45, 60, 75 and 90 em were wed for the experiment. The following conclusion was derived from the study. (1) True model theory can be sufficiently utilized to study the wheel traction and linkage on lands. (2) For both dry and wet sands, Cone Index(CI) and soil shear parameters (c, ${\phi}$) with bulk density (${\gamma}$) were found to be good measures of soil physical properties which are pertinent to predict the performance of the powered rigid wheel-soil system.

• International Journal of Automotive Technology
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• 제5권2호
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• pp.69-76
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• 2004

This paper evaluates the effectiveness of four-wheel-steering system from the viewpoint of lane-keeping control theory. In this paper, the lane-keeping control system is designed on the basis of the four-wheel-steering automobiles whose desired steering response is realized with the application of model matching control. Two types of desired steering responses are presented in this paper. One is zero-sideslip response, the other one is steering response which realizes zero-phase-delay of lateral acceleration. Using simplified linear two degree-of-freedom bicycle model, simulation study and theoretical analysis are conducted to evaluate the lane-keeping control performance of active four-wheel-steering automobiles which have different desired steering responses. Finally, the evaluation is conducted on straight and curved roadway tracking maneuvers.