• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.442-445
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• 1995

This paper presents the position tracking control of a laser scanning mirror system in which piezoelectic actuator is incorporated. Using the shear mode of the piezoelectric actuator,angular oscillation of a laser scanning mirror is derived. Torsion bar is rhen designed and attached to the piezoelctric actuator in order to magnify the amplitude generated by the actuator. Finite element modeling and analysis are essntial for designing the piezoelectic actuator. The torsional resonance mode of the piezoelectric actuator is found from the model analysis of the actuator and the mechanical shear is matched with the driving frequency. Transfer function between the electrical excitation and the mechanical shear deformation at resonance frequency is found form the response of the actuator calculated by the finite element analysis and the governing equation of the system is derived from d'Alembert's principle. Tracking control performance for desired trajectory which is, in fact, sinusoidal curve is presented in order to demonstrate the validity of the proposed system.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.763-768
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• 2002

This paper presents a mathematical model predicting the temperature distribution in rotating GMA welding. The bead width increases with rotation frequency at the same rotation diameter because the molten droplets are deflected by centrifugal force. The numerical solution is obtained by solving the transient three-dimensional heat conduction equation considering the heat input from the welding arc, cathode heating and molten droplets. Generally in GMA welding the heat input may be assumed as a normally distributed source, but the droplet deflection causes some changes in the heat input distribution. To estimate the heat flux distribution due to the molten droplet, the contact point where the droplet is transferred on the weld pool surface is calculated from the flight trajectory of the droplets under the arc plasma velocity field obtained from the arc plasma analysis. The numerical analysis shows a tendency of broadened bead width and shallow penetration depth with the increase of rotating frequency. The simulation results are in good agreement with those obtained by the experiments under various welding conditions.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1662-1667
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• 2005

In this paper, analysis, design, control and prototype construction of a wearable wire-driven haptic interface called HapticPen is discussed. This device can be considered as a wire driven parallel mechanism which three wires are attached to a pen-tip. Wire tensions are provided utilizing three DC servo motors which are attached to a solid frame on the user's body. This device is designed as input as well as output device for a wearable PC. User can write letters or figures on a virtual plate in space. Pen-tip trajectory in space is calculated using motor encoders and force feedback resulting from contact between pen and virtual plate is provided for constraining the pen-tip motion onto the virtual plane that can be easily setup by arbitrary non-collinear three points in space. In this paper kinematic model, workspace analysis, application analysis, control and prototype construction of this device are presented. Preliminary experiments on handwriting in space show feasibility of the proposed device in wearable environments.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.63.5-63
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• 2001

In this paper, moving objects tracking and dynamic characteristic analysis are studied. Kohonen´s self-organizing neural network models are used for moving objects tracking and time delay neural networks are used for dynamic characteristic analysis. Instead of objects brightness, neuron projections by Kohonen Networks are used. The motion of target objects can be analyzed by using the differential neuron image between the two projections. The differential neuron image which is made by two consecutive neuron projections is used for center detection and moving objects tracking. The two differential neuron images which are made by three consecutive neuron projections are used for the moving trajectory estimation.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1996년도 추계학술대회논문집
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• pp.160-165
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• 1996

This paper presents the development of video-based 3-dimensional tracking system. Measurement of human motion is important in the application of ergonomics. The system uses advanced direct video measurement technology. Passive retro-reflecting markers are attached to a subject and movements of markers are observed by two CCD cameras. Infrared light emitted near the CCD cameras is reflected by the markers and is detected by the cameras. The image ae captured by Samsung MVBO2 board and the center of markers is calculated by DSP program. The position of markers are transferred from MVB02 board to the computer through AT bus. The computer then tracks the position of each marker and saves the data. This system has dynamic accuracy with 1% error and the sampling rate to 6-10 Hz, and can analyse the trajectory and speed of the marker. The results of this study can be used for operators motion analysis, task analysis, and hand movement characteristic analysis.

• 한국환경과학회지
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• 제9권1호
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• pp.57-64
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• 2000

The sensitivity analysis of two short-term models (ISCST3, INPUFF2.5) is performed to improve the model accuracy. It appears that the sensitivities on the changes of wind speed, stack height and stack inner diameter in the near distance from source, stability and mixing height in the remote distance form source, are significant. Also the gas exit velocity, stack inner diameter, gas temperature and air temperature which affect the plume rise have some effects on the concentration values of each model within the downwind distance where final plume rise is determined. And in modeling for the atmospheric dispersion of point pollutant source INPUFF2.5 can calculate amount, trajectory of puff and concentration versus time at each receptors. So, it is compatible to analyze distribution of point pollutants concentration at modeling area.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1996년도 춘계 학술대회논문집
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• pp.125-130
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• 1996

A numerical analysis is conducted on heat transfer and fluid flow of a plasma spraying process under the DC-RE hybrid electromagnetic field. Plasma flow is analyzed by using Eulerian approach and the equation of particle motion is simultaneously solved using a trajectory analysis with a lumped-heat-capacity model. Axisymmetric two dimensional electromagnetic fields governed by Maxwell's equations are solved based on a vector potential concept. The effects of the RF electromagnetic field on the temperature and velocity fields of the turbulent plasma flow are clarified. Control characteristics of phase changes and dispersed features of particles by applying the RF electromagnetic field are also clarified in an attempt to improve the plasma spraying process

• 한국대기환경학회지
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• 제31권6호
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• pp.520-529
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• 2015

The ambient $PM_{2.5}$ samples were collected by $PM_{2.5}$ sampler from September 2010 to December 2012 at Daegu University, Gyeongsan. A total of 260 samples were collected and 27 species were analyzed by inductively coupled plasma, ion chromatography, and thermal optical reflectance methods. Factor analysis identified four sources such as biomass burning source/secondary aerosol source, soil source, industry source, and incinerator source/mobile source. Also, backward trajectories were calculated using HYSPLIT 4 (Hybrid single-particle lagrangian integrated trajectory) model and PSCF (Potential source contribution function) model was applied to identify the possible source locations of carbonaceous species and water soluble ions species. PSCF results showed that the possible source locations of most chemical constituents measured in Gyeongsan were the industrial areas in the eastern coast of China, northeast regions of China, the Gobi Desert, and east sea of Korea.

• 자동차안전학회지
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• 제6권2호
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• pp.61-66
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• 2014

This paper described on the motion of hybrid tractor trajectory for powertrain system. The dynamics behavior used to the tractor according to the characteristics of the road surface using $Daful^@$ analysis. The tractor industry is facing to a big problem about rising gas price and exhaust gas environment. Because it was possible overcoming the past drawback, hybrid vehicle had been decided as the best technical way since it has started operating the internal combustion engine with the electric power as the motive power. The vehicle structures have designed the model of a major power transmission factor. The simulation realized in this paper that motion of tractor being turned by torque and force of each joints. Driving characteristics, especially in recent years, IVHS (Intelligent Vehicle Tractor / System) technology, while receiving a lot of attention because of the tractor and the need to pursue high function is emerging as a more and more.

• Journal of Welding and Joining
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• 제28권1호
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• pp.100-106
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• 2010

In this paper crack propagation analyses in the dissimilar metal weldment of a nozzle were performed using a finite element alternating method (FEAM). A two-dimensional axisymmetric finite element nozzle model was prepared and welding simulation including the thermal heat transfer analysis and the thermal stress analysis was performed. Initial cracks were inserted at weld and heat affected zone in the finite element model which has welding residual stress distribution obtained from the welding simulation. To calculate crack propagation trajectories of these cracks, a new fatigue crack evaluation module was developed in addition to the previous FEAM program. With the new FEAM fatigue crack evaluation module, crack propagation trajectory and crack growth time were calculated automatically and effectively.