• Journal of Institute of Convergence Technology
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• v.1 no.2
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• pp.6-15
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• 2011

This paper reports the design and fabrication of a micro-electro-mechanical-system(MEMS)-based electrostatic angular microactuator for a dual-stage servo. The proposed actuator employs a novel electrode pattern named "skewed electrode array(SEA)" scheme. It is shown that SEA has better linearity than a parallel plate type actuator and stronger force than a comb-drive based actuator. The moving and the fixed electrodes are arranged to make the driving force perpendicular to the rotating moment of arm. By changing the electrode overlap length, the magnitude of electrostatic force and stable displacement will be changed. In order to optimize the design, an electrostatic FE analysis was carried out and an empirical force model was established for SEA. A new assembly method which will allow the active electrodes to be located beneath the slider was developed. The active electrodes are connected by inner and outer rings lifted on the base substrate, and the inner and outer rings are connected to platform on which the slider locates. Electrostatic force between active electrodes and platform can be used for exiting out of plane modes, so this provides the possibility of the flying height control. A microactuator that can position the pico-slider over ${\pm}0.5{\mu}m$ using under 20 volts for a 2 kHz fine-tracking servo was designed and fabricated using SoG process.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.3
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• pp.215-223
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• 2007

When the propulsion shafting system of marine diesel engine is designed. the vibratory stresses on shafts should be reviewed and be satisfied with limits which are laid down by classification societies In addition. the torsional vibration aspects for crankshaft of main engine are requested to be checked by engine designers. Especially. for the 4, 5, and 6-cylinder engines. the 2nd order moment compensator(s) may be installed to compensate the external moments of engine and not to excite the hull girder vibration. This moment compensator which is mounted on fore and/or after-end of engine is driven by the roller chain drive for some of MAN 2-stroke diesel engines. While the engine is running, the roller chain Is worn down, which causes the extension of roller chain. The chain therefore should be checked and tightened by periods in order to keep its functionality. However. when the torsional angular acceleration of chain drive exceeds the certain limit. the chain will suffer the excessive slack and transverse vibration. This may cause fatigue, wear or damage on the chain and the chain ultimately may be broken. The research object of this thesis is to review factors which affect the angular acceleration of chain drive and to find out how to decrease the angular acceleration of driving chain by checking factors which have a major contribution to acceleration reduction using the statistical method of DOE(design of experiment), correlation analysis and regression analysis methods.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.4
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• pp.44-49
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• 2011

The crawler crane, which consists of a lattice boom, a driving system, and movable vehicle, is widely used in a construction site. It needs to be installed an overload limiter to prevent the overturning accident and the fracture of structure. This research is undertaken to provide the relation formula for designing the overload limiter as follows: First the relation formulas between the wire-rope tension and the hoisting load or the overturning ratio according to the luffing angle and length of a lattice boom are established. Secondly the derived formulas are corrected by using the compensated angle considering the deflection of boom through the finite element analysis. The stiffness analysis is carried out for 30-kinds of models as a combination of 6-kinds of luffing angle and 5-kinds of length of boom. Finally the shape design of a stick type load cell, which is the device to measure the wire-rope tension, is performed. 5-kinds of notch radius and 5-kinds of center hole radius are adopted as the design parameter for the strength analysis of the load cell.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.6
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• pp.521-525
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• 2011

Lane marking detection is one of important issues in the field of autonomous mobile robot. Especially, in urban environment, like pavement roads of downtown or tour tracks of Science Park, which have continuous patterns on the surface of the road, the lane marking detection becomes more important ability. Although there were many researches about lane detection and lane tracing, many of them used vision sensors mainly to detect lane marking. In this paper, we obtain 2 dimensional library data of 'Intensity' and 'Distance' using one laser rangefinder only. We design a simple classifier and filtering algorithm for the lane detection which uses only one LRF (Laser Range Finder). Allowing extended usage of LRF, this research provides more functionality not only in range finding but also in lane detecting to mobile robots. This work will be technically helpful for robot developers to design more simple and efficient autonomous driving system using LRF.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.10
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• pp.866-872
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• 2008

Torsional oscillations of the mechanical drivetrain in electric vehicles are generated under rapid driving conditions. These lead to an uncomfortable jerking of the vehicle and to an increased stress of the mechanical components. To analyze this phenomenon, a drivetrain model is constructed with lumped parameters. The model parameters are identified by geometrical design data and experimental tests. The proposed model is validated by simulation and experimental tests in the time and the frequency domains. As a result, the torsional oscillations are observed at 7Hz of a low damped natural frequency. Also, the analysis of the effect of the parameter variations on the oscillations shows that the oscillation characteristic is mainly dependent on the rotor inertia, and the stiffness of the mounting of the drive aggregate and the driveshaft. The results will be utilized on the basis of the design of an electric drivetrain and an active control of drivetrain oscillations.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.1
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• pp.33-42
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• 1997

The reciprocating compressors are widely used in industrial fields for its simplicity in principle and high efficiency. But the design of it requires rigorous experiments due to its high dependence on many design parameters. In this work, a mathematical model is developed so that we can analyze the gas-solid interaction during the whole working processes of a reciprocating compressor. The governing equations, which represent the fluid-solid interaction, was derived from the unsteady Bernoulli's equation with the assumption of quasi-steady working process. The valve itself was assumed to be a one degree of freedom spring-mass-damper system. A simple thermodynamic relation, the ideal gas state equation, was used to give it an external force term assuming that the refrigerant behaves like an ideal gas. It was suggested to use a motor of higher driving frequency to enhance the performance of the reciprocating compressor without causing a faster failure of the valve.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1593-1598
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• 1994

Recently rotary-arc, thermal expansion and their composite interrupters are widely used in the distribution power system because they have lots of advantages in making the larger interrupting capacity, the smaller size, the lighter weight and the less surge. A model interrupter of rotary-arc type, which has constant stroke and thermal expansion volume, was studied by varying the design parameters, i.e. the number of turns of the driving coil, the inner diameter of the moving contact, the gas pressure and the shape of the fixed contact for this project. Short cicuit current interrupting tests were conducted to the model interrupters by varying the requirements from 42% to 175% of the test voltage, interrupting current and transient recovery voltage for the test duty No.4 of 7.2kV 12.5kA single phase test. The pressure rise, minimum and maximum arcing times were analyzed for each model interrupter. All types of model interrupters showed good interrupting performances and sufficient design margins for the ratings.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.51-53
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• 2018

This paper describes the design and implementation of a circuit consisting of a simmer power supply unit and a series trigger unit that can be applicable to xenon lamp driving. An LCC resonant converter based on the continuous conduction mode (CCM) is applied to the simmer circuit and by using the current output control it is possible to maintain the ionization of the lamp which has the negative resistance load characteristic. At the same time, in order to generate a high voltage, a series trigger circuit which has a number of capacitors and diodes is designed. The generated high trigger output voltage could ionize the xenon gas. This paper explains the configuration and features of the integrated circuit system, and verifies the proposed design and stable operation of the xenon lamp. The experimental and simulation results show the not only rationality but also stability of the proposed circuit.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.421-426
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• 2003

Recently, mixers are being widely used in the water purification plant in order to increase the filtration efficiency. The mixer normally consists of impeller, shaft, hub, reduction gear, and the driving motor. It is one of the key design issues to confirm that the vibration caused by the rotation of the shaft should not coincide with the natural vibration frequency of the shaft itself. The vibration characteristics of the hydrofoil type mixer, which is the most widely used in real plants are evaluated through the finite element modeling and verified by experiment using the mock-up facility. The fundamental natural frequency of the mixer's shaft is found to be around 1.8 Hz which showed in good agreement with the experiment. The higher natural frequencies to the 2nd, 3rd, and 4th modes are also verified by the experiment. Thus the developed model is to be utilized for the structural design of the real mixer system.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1623-1624
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• 2006

It is a paper for design, manufacture and estimation of industry inkjet head. Simulations for Actuator, Ink flow and Ejection are executed for securing design ability. Relations between droplet and properties of ink are explained closely through simulation for nozzle. Actually, two silicon plates are made by dry and wet etching and directly bonded. PZT materials is attached on the bended ink flow part and cut to $540{\mu}m$ interval by dicing saw. Actuator was seen variation within 10% between simulation and actual head. Through the ejection estimation, it is shown that stabilized driving voltages change according to viscosity and surface tension of metal ink. Using the metal ink of viscosity of 4.8 cps and surface tension of 0.025 N/m, it is possible to eject the stable droplets with 5m/s, 20 pl, 5 kHz.