• Journal of the Korean Society for Precision Engineering
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• v.12 no.2
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• pp.59-68
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• 1995

In this study, the effects of the power transmission units on the rotational accuracy are investigated experimentally in a hydrostatic spindle. The effects of warm up time, unbalancing and the position of measuring sensor are pre-examined for the determination of measuring conditions. The misalignment of the power transmission units and the vibration excited by the fluctuation of belt are considered as the dominant parameters of error motion. The variation and scatter of run out at the range of 0 to 3,000rpm in rotational speed are appropriated for the camparison of availabilities of the transmission units to precision spin- dles.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.962-963
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• 2008

본 논문에서는 상하방향의 추진력을 필요로 하는 클린룸용 리프트 시스템의 구동원으로 고출력 선형전동기 적용에 관한 연구를 진행하였다. 기존의 리프트 시스템은 회전형 전동기와 부가적인 동력전달장치를 이용하여 동력을 전달하는 간접구동방식으로, 선형전동기를 적용한 직접구동방식에 비해 구조적으로 복잡하며, 클린룸내에서 청정도에 영향을 주는 분진발생이 상대적으로 많아진다. 선형전동기를 리프트 시스템에 적용함으로써 시스템의 컴팩트화, 구동속도 향상, 그리고 신뢰성 향상을 통한 성능개선이 가능하다. 본 연구에서는 실제 제작한 리프트 실험장치를 통하여 선형전동기의 구동성능을 분석하고, 제안한 리프트 시스템의 타당성을 검증한다.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.696-701
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• 2000

In this study, a mathematical model fur analyzing the shift characteristics is proposed. The proposed model comprises power transmission system and vehicle system, which are coupled. And On-road car test is carried out in order to extract model parameters. Tile model is composed of a detailed powertrain, an engine/AT housing, a simplified suspension system. tires and a vehicle body model. On the test, the vehicle accelerations and pitch ratio are measured by using accelerometers and gyro sensor. The other data, for example speeds, a throttle position and a brake signal, are taken from sensors which already exist in the vehicle. Using natural frequency and characteristic equation, vehicle model parameters are extracted from experimental data.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.684-689
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• 2000

In this paper, the equations of motion about vehicle, powertrain and brake system were derived. The vehicle has eight degrees of freedom with nonlinear tire model and the powertrain has two degrees of freedom containing engine, torque converter and four speed automatic transmission. The brake system has two states about front and rear brake line pressures. The transient tire model with first order time lag is also subjoined for low speed or stop-and-go simulation. The modeling was derived considering two points - the fidelity and the simplicity. The simulation using this model is similar with real vehicle dynamic behavior and the model is made as simple as possible far fast simulation. It is validated that the derived vehicle model can be applicable to the real time simulation.

• Journal of Power System Engineering
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• v.9 no.4
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• pp.58-64
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• 2005

주파수 영역 민감도 해석법은 동적 시스템의 전달함수에 대한 설계 파라미터의 변화에 의한 효과를 파악하기 위해 사용되어 왔으며, 이때의 민감도 함수는 시스템 설계 파라미터에 대한 시스템 전달 함수의 편미분 값이다. 일반적으로 종래의 주파수 영역 민감도 해석은 직접 미분법이나 라플라스 변환이 사용되어 왔다. 라플라스 변환을 사용하는 경우에 시스템의 차수가 증가할수록 역행렬 조작은 매우 많은 시간을 필요로 하며 또한 어려운 작업이다. 본논문에서는 이러한 다점을 보완하기 위하여 푸리에변환을 이용한 민감도 기법을 제시하였다. 파라미터의 변화에 대한 진폭-주파수 특성의 민감도 해석을 간단한 2자유도 모델과 로터 다이나믹 시스템에 적용하였다.

• Journal of Power System Engineering
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• v.9 no.1
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• pp.42-49
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• 2005

The vibration analysis of a rectangular plate with stiffeners is formulated by using the transfer stiffness coefficient method (TSCM). This method is based on the concept of the successive transmission of stiffness coefficients which are defined as the relationship between the force vector and the displacement vector at an arbitrary nodal line. In order to confirm the validity of the present method, bending vibration analysis for a rectangular plate with stiffener is carried out on a personal computer by using the present method and the finite element method (FEM). Through comparing computational results of the TSCM and the FEM, the effectivness of the TSCM from the viewpoint of computational cost, that is, computational time and storage is demonstrated.

• Journal of Power System Engineering
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• v.9 no.4
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• pp.202-208
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• 2005

The genetic algorithm (GA) which is one of the popular optimum algorithm has been used to solve a variety of optimum problems. Because it need not require the gradient of objective function and is easier to find global solution than gradient-based optimum algorithm using the gradient of objective function. However optimum method using the GA and the finite element method (FEM) takes many computational time to solve the optimum structural design problem which has a great number of design variables, constraints, and system with many degrees of freedom. In order to overcome the drawback of the optimum structural design using the GA and the FEM, the author developed a computer program which can optimize frame structures by using the GA and the generalized transfer stiffness coefficient method. In order to confirm the effectiveness of the developed program, it is applied to optimum design of plane frame structures. The computational results by the developed program were compared with those of iterative design.

• Journal of KSNVE
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• v.7 no.5
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• pp.853-860
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• 1997

For this study, the multi-degree of freedom analysis model of torsional vibration was developed. This model is combined with mass moment of inertia and torsional spring in two wheel drive and four wheel drive vehicle. We compared and analyzed torsional vibration characteristics by natural frequencies and mode shapes which are obtained by free vibration analysis of this model. And we studied torsional vibration contribution of driveline elements by performing the forced vibration analysis of engine excitation torque. The validity of this model is demonstrated by the field test. The reduction effect of the torsional vibration along the driveline design factor is presented by the analytical results.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.2
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• pp.185-191
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• 2001

In many papers, the powertrain system generally has been madeled as one-dimensional torque model. One-dimensional powertrain model may calculate the torque correctly but it does not consider the non-rotational degrees-of-freedom of the powertrain components and the interaction of these degrees-of-freedom with the vehicle body frame and suspension. To consider the non-rotational degrees of freedom, the differential is modeled as a three-dimensional rigid body in this paper. A constant velocity joint is newly formulated and a relative constraint is also formulated to model the motion transfer due to gear ratio of the differential. Implementing the proposed powertrain system in the multibody model, more detail dynamic responses can be obtained. Obtained outputs such as reaction torques on the constant velocity joint and reaction forces on the rack can be useful data in the design of a powertrain.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.1
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• pp.63-74
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• 1996

Automatic transmission for heavy duty vehicles is a part of the power pack which includes steering and braking systems. This transmission in different from the one for passenger car. Therefore, in order to understand the trend of the important design parameters, maneuverability, acceleration performance and maximum speed, we need to analyze the total performance characteristics of the power transmission systems. In this study, modeling of the automatic transmission in heavy duty vehicle is carried out and the performance analysis method is presented. Results can be used for performance estimation data in the analysis for several combination method which determines the optimal parameters on the basis of penalty functions and weightings. And the estimation method of the important performance parameters such as engine inertia or power loss of engine by experiments is presented.