• Transactions of the Korean Society of Mechanical Engineers
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• 제7권1호
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• pp.36-45
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• 1983

In order to characterize the machine tool feed-drive dynamics, thread cutting experiments are performed with cutting conditions and slide-way lubrication varied. During the experiments, the carriage, tool post and tail stock accelerations in the feed direction are measured, and analyzed by employing the spectral analysis method. It is found that the tool post vibration in the feed direction during thread cutting operation is mainly due to those of the carriage and the workpiece. Other structure-related vibrations show little effects on the tool post vibration. The characteristics of the carriage vibration is shown to be fairly consistent, except the vibration amplitude, regardless the variations in cutting condition and lubrication within the experimental range. The experimental results suggest that the feeddrive system can be modelled as a 2 DOF damped oscillatory system.

• Korean Journal of Computational Design and Engineering
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• 제12권2호
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• pp.126-136
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• 2007

Teleconferences have been used in business sectors to reduce traveling costs. Traditionally, specialized telephones that enabled multiparty conversations were used. With the introduction of high speed networks, we now have high definition videos that add more realism in the presence of counterparts who could be thousands of miles away. This paper presents a new technology that adds even more realism by telecommunicating with hand gestures. This technology is part of a teleconference system named SMS (Smart Meeting Space). In SMS, a person can use hand gestures to manipulate meeting data that could be in the form of text, audio, video or 3D shapes. Fer detecting hand gestures, a machine learning algorithm called SVM (Support Vector Machine) has been used. For the prototype system, a 3D interaction environment has been implemented with $OpenGL^{TM}$, where a 3D human skull model can be grasped and moved in 6-DOF during a remote conversation between distant persons.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 1995년도 춘계학술대회논문집; 전남대학교, 19 May 1995
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• pp.121-128
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• 1995

The results are summarized as what follows: 1) The modeling of thin beams, which is a continuous system, into a two DOF system yields satisfactory results for the chaotic vibrations. 2) The concept of "natural forcing function" derived from the eigenfunction of the bifurcation mode is very useful for the natural responses of the system. 3) Among the perturbation techniques, HBM is a good estimate for the response when the geometry of motion is known. 4) It is known that there exist periodic solutions of coupled mode response for somewhat large damping and forcing amplitude, as well as weak damping and forcing. 5) The route-to-chaos related with lateral instability in thin beams is composed of period-doubling and quasiperiodic process and finally follows discontinuous period-doubling process. 6) The chaotic vibrations are verified by using Poincare maps, FFT's, time responses, trajectories in the configuration space, and the very powerful technique Lyapunov characteristics exponents.exponents.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
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• pp.481-487
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• 1997

The development of transportation and construction equipment has required higher engine power and lower operation cost. The sound which the engine emits often degrade the performance of the whole system which adopts that engine. Specially the marine engine requires high restriction on the noise level for the customer's comfort and safety. The noise and vibration of Diesel engine must be carefully considered in the early design step. The double antivibration system is effective to increase the efficiency of antivibration, and the acoustic enclosure for reducing the noise level. 2 DOF model was effective to estimate the antivibration performance, which allows to determine the mass of the engine bed and the specification of the engine mount. The mass distribution of the enclosure system can be considered effectively by using the FEM model. The design contains structurally rigid engine bed by FEM, which is for reducing the influence of the flexible vibration, rubber mount selection as well as the acoustic enclosure design.

• International Journal of Automotive Technology
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• 제7권2호
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• pp.167-172
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• 2006

A design of controller for vehicle dynamic control(VDC) and its implementation on the real vehicle were introduced. The controller has been designed using a three-degrees-of-freedom(3DOF) yaw plane vehicle, and the control algorithm was implemented on the vehicle by control prototyping system dSPACE. A hybrid control algorithm, which makes full use of the advantages of robust and fuzzy control, was adopted in the control system. Field test results show that the performance of the vehicle handling dynamics with hybrid controller is improved obviously compared to that without VDC and with simple robust controller on skiddy roads(friction coefficients lower than 0.3).

• Proceedings of the KSME Conference
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• 대한기계학회 2004년도 춘계학술대회
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• pp.846-851
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• 2004

In this paper, a sliding mode control based on disturbance observer is proposed to attenuate disturbance responses in an active magnetic bearing system, which is subject to base motion. An algorithm for exactly decoupling the disturbance estimation dynamics from the sliding mode dynamics is developed. It is also shown that the proposed method preserves the robustness of the sliding mode and asymtotically achieves zero regulation error, in the presence of external disturbances and parametric uncertainties. The proposed control is applied to a 2-DOF active magnetic bearing system subject to base motion. The feasibility of the proposed technique is illustrated, and the results of an experimental demonstration are shown.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 한국신호처리시스템학회 2003년도 하계학술대회 논문집
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• pp.177-182
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• 2003

The robust output tracking control problem of general nonlinear MIMO systems is discussed. The robustness against parameter uncertainties is considered. In this paper, we proposed the robust output tracking control scheme for a class of MIMO nonlinear dynamical systems using output feedback linearization method. The presented control scheme is based on the VSS. We assume that the nonlinear dynamical system is minimum phase, the relative degree of the system is r$_{1}$＋r$_{2}$＋…r$_{m}$$\leq$ n and zero dynamics is stable. It is shown that the outputs of the closed-loop system asymptotically track given output trajectories despite the uncertainties while maintaining the boundedness of all signals inside the loop. And we verified that the proposed control scheme is then applied to the control of a two degree of freedom (DOF) robotic manipulator with payload.d.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.64.2-64
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• 2001

In this paper, fabricated is a motion capture and attitude detection system for Head Mounted Display HMD composed of three low-price and low-grade micro gyroscopes and a micro-controller, To calculate attitude of a body, modified INS algorithm is used. Because the micro gyroscope has much bias drift error, scale factor error, and run-to-run bias error, the motion of a body can not be measured exactly if the general INS algorithm and micro gyroscopes are used. To reduce the errors, three accelerometers can be used. In this case, however, the size and power consumption become too large to use in HMD system. The modified INS algorithm use the grid map and the characteristics of the human motions.

• International Journal of Control, Automation, and Systems
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• 제2권1호
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• pp.83-91
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• 2004

The purpose of this paper is to obtain an accurate nonlinear system model to test various control schemes for a motion control system that requires high speed, robustness and accuracy. An industrial sewing machine equipped with a Brushless DC motor is considered. It is modeled by a neural network that is configured as an output-error dynamical system. The identified model is essentially a one step ahead prediction structure in which past inputs and outputs are used to calculate the current output. Using the model, a 2 degree-of-freedom PID controller to compensate the effects of disturbance without degrading tracking performance has been de-signed. In this experiment, it is not preferable for safety reasons to tune the controller online on the actual machinery. Experimental results confirm that the model is a good approximation of sewing machine dynamics and that the proposed control methodology is effective.

• Journal of the Institute of Electronics Engineers of Korea SC
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• 제49권4호
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• pp.55-60
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• 2012

When operating a surveillance system in the maritime environment, its stabilization performance is degraded due to undesirable disturbance motions. For accurate target pointing of a 2-axes surveillance system on shipboard, the kinematic stabilization is first applied, which compensates a deviated motion via coordinate transformations of attitude information. Resultantly, the stabilization error is no longer reduced due to less accuracy of a MEMS sensor and kinematic constraint, leading to introduction of the image stabilization as a complementary function. And for real-time execution of the present dual stabilization scheme, a HILS (Hardware In the Loop Simulation) test bed including 6-dof motion simulator has been constructed, and through the obtained HILS data, it has been confirmed that the stabilization is successfully.