• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.108.4-108
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• 2002

This paper aims to derive a mathematical model of the dynamics of handling tasks in robot fingers which stably grasps and manipulates a rigid object with some dexterity. Firstly, a set of differential equation describing dynamics of the manipulators and object together with geometric constraint of tight area-contacts is formulated by Lagrange's equation. Secondly, problems of controlling both the internal force and the rotation angle of the grasped object under the constraints of tight area-contacts are discussed. The effect of geometric constraints of area-contacts on motion of the overall system is analyzed and a method of computer simulation for differential-algebraic equations of overall...

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.9-12
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• 2000

InP/lnGaAs heterojunciton phototransistors (HPTs) with transparent emitter contacts were fabricated and characterized. Indium Tin Oxide was RF sputtered for the emitter contacts. By comparison with InP/InGaAs HBTs, the dc characteristics of InP/lnGaAs HPTs demonstrated offset voltage due to ITO emitter contacts and similar common emitter current gain. The model parameters were extracted and a simple SPICE simulations were performed.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.12
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• pp.115-121
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• 1994

Aluminum films were chemically vapor deposited for the metallization of the integrated circuits and the spiking characteristics of the direct CVD Al/Si contacts were investigated. When the aluminum was formed by CVD uniform consumption of the substrate silicon was observed, which is quite different from the phenomena observed in sprttered Al. Silicon consumption occured during the deposition of CVD Al and the erosion depth of the silicon was several hundred $\AA$ when the continuous films were formed on the substrate while much less erosion of the silicon occured when the Al were formed in islands. When the submicron contacts were selectively plugged, contact resistances were very low and the erosion depth of the silicon was trivial.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.10
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• pp.887-898
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• 2004

In this paper a mathematical framework fur deriving acceleration bounds from given joint torque limits of multiple cooperating robots are described. Especially when the different frictional contacts for every contact are assumed and the torque limits are given in 2-norm sense, we show that the resultant geometrical configuration for the acceleration is composed of corresponding parts of ellipsoids. Since the frictional forces at the contacts are proportional to the normal squeezing forces, the key points of the work includes how to determine internal forces exerted by each robot in order not to cause slip at the contacts while the object is carried by external forces. A set of examples composed of two robot systems are shown with point-contact-with-friction model and insufficient or proper degree of freedom robots.

• Tribology and Lubricants
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• v.23 no.2
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• pp.49-55
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• 2007

A numerical analysis of elastohydrodynamic lubrication of elliptical contacts with both rolling and spinning has been carried out. A finite difference method with non-uniform grid systems and the Newton-Raphson method are applied to solve the problems. The velocity vectors resulting from combined spinning and rolling/sliding motion lead to asymmetric pressure distributions and film shapes. Pressure distributions, film contours and variations of the minimum and central film thicknesses are compared with various spin-roll ratios. Reduction of the minimum film thickness under spinning is remarkable whereas the central film thickness is relatively less. The spin motion have large effect on variations of the minimum film thickness with load parameter which are small in pure rolling/sliding cases. Therefore present numerical scheme can be used in the analysis of general elliptical contact EHL problems and further studies are required.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.593-596
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• 2001

It is necessary for calculation of repulsion forces acting on the closed electric contacts flowing over-current. e.g. inrush current and overload currents, to do optimum design of switching devices. In this paper. the forces and flux densities generated by currents at the contact point when circuit breakers are in closed state are obtained by using 3D finite element methode. To be convinced of the results, we measure electrogmanetic repulsion forces on contacts by measuring voltage between opened contacts in MCCB

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.05a
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• pp.43-45
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• 1988

Four W/Cu system(60wt%W-40wt%Cu, -0.lwt%Ni, -0.5wt%Ni, -0.lwt%C) and four WC/Cu system(60wt%WC-40wt%Cu, -0.lwt%Ni, -0.5wt%Ni, 0.lwt%C) electrical contacts were prepared by a press-sinter-infiltration process to compare with their properties. Hardness and electrical conductivity are proportional to the refractory metal(W or WC) properties and showed the effect of additives. Arc erosion trend of switch test is changed by current level. High currant test at 1kA showed a different crack formation pattern and erosion mode between W/Cu system and WC/Cu system contacts.

• Tribology and Lubricants
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• v.24 no.6
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• pp.355-361
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• 2008

In highly stressed machine elements such as angular contact ball bearings and toroidal type traction drives, the elastohydrodynamic lubrication of elliptical contacts with both rolling and spinning motion are occur. In this paper, a finite difference method with non-uniform grid systems and the Newton-Raphson method are applied to solve the problems. Pressure distributions, film contours and variations of the minimum and central film thicknesses are compared with various ellipticity parameter, dimensionless speed and load parameter. The results showed that the spinning motion has significant influence especially on the film shapes. Reduction of the minimum film thickness under spinning is remarkable whereas the central film thickness is relatively less. Especially variations of the minimum film thicknesses with rolling velocity, load and ellipticity ratio are a great different from those of pure rolling. Therefore present numerical scheme can be used in the analysis of general elliptical contact EHL problems and further studies are required.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.261-264
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• 1990

The specific contact resistance(SCR) of metal-semiconductor interface is an important design parameter for VLSI interconnecting technology. As the critical feature size of the integrated structures decrease, the physical size of ohmic contacts will also decrease and the series contact resistance will increase. Al-Si contacts on the annealing condition are studied. The propreties of the contacts depend considerably on the annealing procedures. Barrier height is measured from Capacitance-Voltage characteristics. The specific contact resistance are analyzed using a modified four point method.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.12
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• pp.1956-1964
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• 1989

In this paper, a new method of Hangul recognition is proposed to solve the problems of misrecognition owing to the contacts of FCEs (Fundamental Character Elements) in a Hangul pattern. Structures of FCFs are represented with PAG(Programmed Array Grammar) to recognize an input pattern on 2-D. array of pels., and the unnecessary deformation of the conventional approach can be eliminated by using PEACE parsing which extracts primitives and computes attributes in the course of analyzing the structure of an input pattern. Also, primitive transformation at contacts can afford to confirm all the possible structures of an input pattern and solve the problem of misrecognition owing to the contacts of FCEs. The recognition rate of proposed method for printed Hangul characters shows 96.2% for 1978 Gothic-letters and 92.0% for 1920 Myng-style-letters, respectively.