• 제어로봇시스템학회:학술대회논문집
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• 1990.10a
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• pp.382-387
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• 1990

In this paper, the dynamic modeling and tip position of rotating Timoshenko beam analyzed by means of FEM (finite element method) and Hyperstability MRAC(model referenced adaptive control) technique of each other. The governing equations of the rotating beams are drived from Hamilton's principle. The dynamic model of this multi-link is drived by Lagrange approach. The shear deformation and rotary inertia are incorporated into a finite element model for determining the bending frequencies of the rotating beam. Simulation results for uniform cantilever beams by using the MRAC are compared with the available results. It will be shown that the proposed method offers an accurate and effective one to solve the free vibration problems of rotating beams' stability.

• The korean journal of orthodontics
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• v.17 no.1
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• pp.119-134
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• 1987

This study was undertaken to find out oropharyngeal movement of the class III malocclusion patients during swallowing by using the cinefluoroscopic method. The experimental group was composed of fifteen male adults with class III malocclusion whose mean age was 24.4 yrs. The control group was composed of fifteen male adults with normal occlusion whose mean age was 24.8 yrs. The results were as follows: 1. The horizontal position of the tongue tip was more anterior in the class III malocclusion group than in the normal group through all stages. 2. The tongue level was lower in the class III malocclusion group than in the normal group during stage 1, stage 3, and stage 4. 3. The horizontal position of the hyoid bone was more anterior in the class III malocclusion group than in the normal group during stage 1 only. 4. The tip of the soft palate was lower in the class III malocclusion group than in the normal group during stage 1 only, and there was no significant difference in the velar movement between the class III malocclusion group and the normal group during swallowing. 5. There was a significant difference in the interincisal distance, but no significant difference in the intermolar distance between the class III malocclusion group and the normal group through all stages. 6. Among 4 stages of each group, there was a significant difference in the movements of the dorsum of the tongue, the hyoid bone, and the soft palates And there was a significant difference in the movement .of the tongue tip of the normal group, but no significant difference in the movement of the tongue tip of the class III malocclusion group.

• Journal of Welding and Joining
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• v.16 no.3
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• pp.55-63
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• 1998

Among the position sensing methods available, the arc sensor which utilizes the electrical signal obtained from the welding arc itself is one of the most prevalently used methods, because it has an advantage that no particular sensing device is necessary and real-time sensing of a groove position is possible directly under the arc. The authors have already developed a seam tracking system that contains a new arc sensor algorithm, which uses the relative welding current variation according to the tip-to-workpiece distance in GMA welding. In this study a torch height control algorithm for automatic weld seam tracking was proposed for completing the previous system, which uses an on-off control technique. To implement the torch height control algorithm during weld seam tracking the system parameters which include 2nd averaging range, weighting factor for 2nd moving averaging, and Z-directional basic compensation distance were determined by experimental analysis. Finally the two different height control methods, one is simple on-off control and the other on-off control using a reference current value , were compared in their tracking abilities.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.3
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• pp.218-224
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• 2007

Although piezoelectric materials such as PZT have been widely used as actuators in the field of active vibration suppression, the use of bare PZT as an actuator may cause some drawbacks such as critical breaks in the installation process, short circuits in the host material and low fatigue performance. The LIPCA-C2 (lightweight piezocomposite actuator) was developed to alleviate these problems. We implemented the LIPCA as an actuator to suppress the vibration of an aluminum cantilever beam with a tip mass. In our test, we used positive position feedback control algorithm. The filter frequency for this type of feedback should be tuned to the natural frequency of the target mode. The first three experimental natural frequencies of the aluminum cantilever beam agree well with the results of finite element analysis. The effectiveness of using the LIPCA as an actuator in active vibration suppression was investigated with respect to the time and frequency domains, and the experimental results show that LIPCAs with PPF control can significantly reduce the amplitude of forced vibrations and the settling time of free vibrations. For a case study, the forced vibration control of several beams with different thicknesses were performed.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.890-895
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• 1990

A theoretical and experimental study of a single link flexible arm a tip mass is presented for the translational end-point positioning. The problem of shifting the end-point from its initial position to the commanded position by the amount of W $_{d}$ is considered for the open loop control such that the base follows up the given path function. The theoretical results are obtained by applying the method of the Laplace transform to the governing equation, and the solution is calculated by the method of numerical inversion. Experimental results are obtained and compared with the theoretical ones.s.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.229-232
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• 1996

The position control accuracy of the robot arm is decreased significantly when a long arm robot is operated at high speed. In this case, the robot arm must be modeled as a flexible structure, not a rigid one, and its control system will be necessarily designed with its elastic modes taken into account. In this paper, the vibration control of a one-link flexible robot arm is presented. The robot system consists of a flexible arm manufactured with thin aluminium plate, AC servomotor with a harmonic drive for speed reduction, optical encoder and accelerometer. The system is modeled with limited number of elastic modes, and its parameters are determined from the results of the experiments. The implemented control schemes are LQ control and sliding mode control. The experiments and digital simulations are carried out to test the validity of the system modeling, controller design, and active control implementation.

• Journal of KSNVE
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• v.6 no.2
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• pp.187-196
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• 1996

A new control strategy to actively control the vibration of a very flexible single link manipulator is proposed and experimentally realized. The control scheme consists of two actuators; a motor mounted at the beam hub and a piezoceramic bonded to the surface of the flexible link. The control torque of the motor to produce a desired angular motion is firstly determined by employing a sliding mode control theory on the equivalent rigid dynamics. The torque is then applied to the flexible manipulator in order to activate the commanded motion. During the motion, underirable oscillation is actively suppressed by applying a feedback control voltage to the piezoceramic actuator. Consequently, the desired tip position is favorably accomplished without vibration. Measured control responses are presented in order to demonstrate the efficiency of the proposed control methodology.

• Korean Journal of Acupuncture
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• v.21 no.4
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• pp.43-51
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• 2004

Objectives : In order to ensure safe acupuncture treatment, the quality of the needle tip is essential. But, there have not been so many studies about the quality of the acupuncture needle tip. For this reason we have been already reported about the quality of acupuncture needle tip in Korea using scanning electron microscope(SEM) in 2002, 2003. In order to compare than other society, we investigated the current condition of the tips of the acupuncture needles sold in Europe. Methods : We obtained the needles made by 7 companies, which are sold currently in Europe, and selected 50 pieces out of 100 pieces from each company by randomized methods. And then we observed the tip of each needle using a scanning electron microscope at ${\times}800$ magnification. Results and Discussion : We found that needles had several defects such as scratch marks on the surface, metallic scuff, lumps and irregularities of the needle tips, stubbed or malformed tips, tips of point off-center, peeled off coated tips, same as Korean needles. There was much difference on the quality of needles among the manufacturers, and some needles seem to need thorough quality control. Allowing for the high price, the quality of some needle in Europe generally are better than that of Korean needles. But some Korean needles hold a top position than European ones in quality. We want a good industrial standard to be made in acupuncture manufacturing fields in the near future, because the safety is not less valuable than the efficacy in medicine.

• The Journal of Korea Robotics Society
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• v.6 no.3
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• pp.220-229
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• 2011

This paper focuses on a development of an anthropomorphic robot hand. Human hand is able to dexterously grasp and manipulate various objects with not accurate and sufficient, but inaccurate and scarce information of target objects. In order to realize the ability of human hand, we develop a robot hand and introduce a control scheme for stable grasping by using only kinematic information. The developed anthropomorphic robot hand, KITECH Hand, has one thumb and three fingers. Each of them has 4 DOF and a soft hemispherical finger tip for flexible opposition and rolling on object surfaces. In addition to a thumb and finger, it has a palm module composed the non-slip pad to prevent slip phenomena between the object and palm. The introduced control scheme is a quitely simple based on the principle of virtual work, which consists of transposed Jacobian, joint angular position, and velocity obtained by joint angle measurements. During interaction between the robot hand and an object, the developed robot hand shows compliant grasping motions by the back-drivable characteristics of equipped actuator modules. To validate the feasibility of the developed robot hand and introduced control scheme, collective experiments are carried out with the developed robot hand, KITECH Hand.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.546-551
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• 1993

A new robust sliding mode controller is formulated for the tip position control of a single-link flexible manipulator with parameter variations. After establishing the plant model characterized by a noncollocated uncertain control system, a sliding surface which guarantees stable sliding mode motion is synthesized in an optimal manner. The surface is then modified to adapt arbitrarily given initial conditions. A discontinuous control law associated with the modified surface is designed by restricting that velocity state variables are not available from direct sensor measurements. Using the proposed control law favorable system responses are accomplished through shortening the reaching phase of state trajectory without increasing maximum control torque as well as undesirable chattering. Furthermore, a low sensitiveness to uncertainties is obtained from inherent salient properties of the proposed control system. Computer simulations are undertaken in order to demonstrate these superior control performance characteristics to be accrued from the proposed methodology.