• 한국기계가공학회지
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• 제18권1호
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• pp.109-115
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• 2019

In arc-welding applying to the present automobile part manufacturing process, a wrist-hollow type arc welding robot can shorten the welding cycle time, because feedability of a welding wire is not affected by a robot posture and thus facilitates high-quality arc welding, based on stable feeding with no entanglement. In this paper, we will propose the optimization of wrist design for a wrist-hollow type 6-Axis articulated robot. Specifically, we will perform the investigation on the optimized design of inner diameter of hollow arms (Axis 4 and Axis 6) and width of the upper arm by using the simulation of robot motion characteristics, using a Genetic Algorithm (i.e., GA). Our simulations are based on $SolidWorks^{(R)}$ for robot modeling, $MATLAB^{(R)}$ for GA optimization, and $RecurDyn^{(R)}$ for analyzing dynamic characteristics of a robot. Especially $RecurDyn^{(R)}$ is incorporated in the GA module of $MATLAB^{(R)}$ for the optimization process. The results of the simulations will be verified by using $RecurDyn^{(R)}$ to show that the driving torque of each axis of the writs-hollow 6-axis robot with the optimized wrist design should be smaller than the rated output torque of each joint servomotor. Our paper will be a guide for improving the wrist-hollow design by optimizing the wrist shape at a detail design stage when the driving torque of each joint for the wrist-hollow 6-axis robot (to being developed) is not matched with the servomotor specifications.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.524-524
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• 2000

We have been developing a method to build one-step-ahead prediction models for time series using genetic programming (GP). Our model building method consists of two stages. In the first stage, functional forms of the models are inherited from their parent models through crossover operation of GP. In the second stage, the parameters of the newborn model arc optimized based on an iterative method just like the back propagation. The proposed method has been applied to various kinds of time series problems. An application to the seismic ground motion was presented in the KACC'99, and since then the method has been improved in many aspects, for example, additions of new node functions, improvements of the node functions, and new exploitations of many kinds of mutation operators. The new ideas and trials enhance the ability to generate effective and complicated models and reduce CPU time. Today, we will present a couple of financial applications, espc:cially focusing on gold price prediction in Tokyo market.

• 제어로봇시스템학회논문지
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• 제10권1호
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• pp.22-29
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• 2004

This paper studies the coordinated trajectory control of an excavator as a kind of robotic manipulators driven by hydraulic actuators. Hydraulic robot system has many non-linearity in dynamics and kinematics, and strong coupling among joints(or hydraulic cylinders). This paper proposes a combined controller frame of the adaptive robust control(ARC) and the sliding mode control(SMC) for the trajectory tracking control of the excavator to preserve the advantages of the both methods while overcoming their drawbacks, namely, asymptotic stability of adaptive system for parametric uncertainties and guaranteed transient performance of sliding mode control for both parametric uncertainties and external disturbance. The suggested control technique is applied for the tracking of a straight-line motion of end-effector of manipulators, and through computer simulations, its trajectory tracking performances and the robustness to payload variation and uncertainties are illustrated.

• Structural Engineering and Mechanics
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• 제22권2호
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• pp.151-167
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• 2006

A p-version of the finite element method in conjunction with the modeling dynamic method using the arc-length stretch deformation is considered to determine the bending natural frequencies of a cantilever flexible plate mounted on the periphery of a rotating hub. The plate Fourier p-element is used to set up the linear equations of motion. The transverse displacements are formulated in terms of cubic polynomials functions used generally in FEM plus a variable number of trigonometric shapes functions representing the internals DOF for the plate element. Trigonometric enriched stiffness, mass and centrifugal stiffness matrices are derived using symbolic computation. The convergence properties of the rotating plate Fourier p-element proposed and the results are in good agreement with the work of other investigators. From the results of the computation, the influences of rotating speed, aspect ratio, Poisson's ratio and the hub radius on the natural frequencies are investigated.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.186-194
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• 2003

This paper proposes a combined controller frame of the adaptive robust control(ARC) and the sliding mode control(SMC) for the trajectory tracking control of the excavator to preserve the advantages of the both methods while overcoming their drawbacks, namely, asymptotic stability of adaptive system fir parametric uncertainties and guaranteed transient performance of sliding mode control for both parametric uncertainties and external disturbance. The suggested control technique is applied for the tracking of a straight-line motion of end-effector of manipulators, and through computer simulations, its trajectory tracking performances and the robustness to payload variation and uncertainties are illustrated.

• 대한기계학회논문집B
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• 제20권12호
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• pp.3960-3969
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• 1996

A fluid flow inside a circular cylinder subject to horizontal and circular oscillation is analyzed theoretically. Under the assumption of small-amplitude oscillation, the governing equations take linear forms. The velocity field is obtained in terms of the first kind of Bessel function of order 1. It was found that a particle describes an orbit close to a circle in the central region and an arc near the side wall. We also obtained the Stokes' drift velocity induced by the traveling wave along the circumferential direction. The Eulerian streaming velocities at the edge of the bottom and side boundary layers were also obtained. It was shown that the vertical component of the steady streaming velocity on the side wall is almost proportional to the amplitude of the free surface motion.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.165-169
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• 2001

Carbon nitride films were grown on Si (100) substrate by a laser-electric discharge method with and without a magnetic field assistance. The magnetic field leads to vapor plume plasma expending upon the ambient arc discharge plasma area. Influence of the magnetic field has resulted in increase of a crystallite size in the films due to bombardment (heating) of Si substrates by energetic carbon and nitrogen species generated during cyclotron motion of electrons in the discharge zone. Many crystalline grains were observed in the morphology of the deposited films by scanning electron microscopy. In order to determine the structural crystalline parameters, X-ray diffraction (XRD) was used to analysis the grown films.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.494-497
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• 2003

A rotating device driven by an Inchworm motor was designed and fabricated to be used as an angie standard system. 1. PZT was adopted as a driving source, while the movement of PZT was guided by the leaf spring employing the elastic transformation of metals. 2. The device could rotate in a 360-degree arc. continuously Performance test of the device showed about 0.02 sec. of the minimum revolution angle and 1/15 rpm of the maimum revolution speed. 3. To improve its performance requires further studies on realizing a shifting device with faster response time, on increasing the output current (capacity) of the power amplifier used to drive PZT, on the dynamic motion of clamping. and on determining the optimum clamping condition

• 한국전기전자재료학회논문지
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• 제15권2호
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• pp.184-189
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• 2002

Carbon nitride films were grown on Si (100) substrate by a laser-electric discharge method with/without a magnetic field assistance. The magnetic field leads to vapor plume plasma expending upon the ambient arc discharge plasma area. Influence of the magnetic field has resulted in increased of a crystallite size int he films due to bombardment (heating) of Si substrates by energetic carbon and nitrogen species generated during cyclotron motion of electrons in the discharge zone. The surface morphology of the films with a deposition time of 2 hours was studied using a scanning electron microscopy (SEM). In order to determine the structural crystalline parameters, X-ray diffraction (XRD) was used to analysis the grown films.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1999년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.223-230
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• 1999

The seismic damage assessment to the postulated earthquake is attempted for the buildings in the model district of Seoul City. The capacity spectrum method is employed in which the vulnerability functions are expressed as functions of the spectral displacement. the database of the building stock is constructed and managed using Geographic Information System software. The model district is selected to represent the typical structural and residential characteristics of Seoul City The structural properties were collected from the design documents. The field inspections were carried out to find out the current status of the building. They are classified into 11 structural types. The fragility curves in HazUS are employed, The ground motions from the postulated earthquakes are simulated using the Boor's methods, The surface soil in the district is classified into 3 profiles using the depth as the parameter. The one-dimensional wave propagation method is used to calculate he filtered ground motion through surface soil layer. The average spectrum of this sample time histories is used as the demand curves. The calculated results are expressed in maps using GIS software ArcView 3.0a