• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.102-102
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• 2003

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.11
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• pp.1033-1038
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• 2000

The unbalanced heavy-loaded elevation-drive system is composed of a hydraulic cylinder, a driving link-mechanism and an equilibrating-mechanism which compensate the static unbalanced moment of the elevation load. The Compensator for the unbalanced moment is composed of a hydrau-pneumatic accumulator and a hydraulic cylinder which act with the elevation cylinder together. Compensation of the variable static-unbalanced moment for the elevation-drive system is very difficult because these mechanisms imply highly nonlinear properties due to air conditioning characteristics and mechanical rotation of the link-mechanism. In this study, through the analysis of the already designed equilibrating-mechanism, the optimal design parameters of the equilibrating-mechanism is suggested.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1033-1036
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• 2007

The optical disc drive has used a high NA objective lens and a shorter wavelength laser diode for high recording density. But high NA and shorter wavelength cause several margins to become short. Focusing and tracking servo has to be more accurate and active tilt compensation mechanism is also needed for coma aberration compensation. In this paper, we proposed 3-axis moving magnet type actuator. For 3-DOF motion, moving coil actuator has to equip 6 wires for supplying 3 independent signals. However, moving magnet type actuator doesn't need to change the configuration of wires because coils are in stator. So, we added tilting mechanism to 2-axis moving magnet actuator which is designed in previous research. Addition of the tilting mechanism cuts down the focusing sensitivity. So, maximization the tilting sensitivity and securing the focusing sensitivity are objectivities of this research. DOE (design of experiments) procedures of electromagnetic circuit are performed for parameter study and the optimization is also performed to maximize the tilt sensitivity. And then the final design is suggested and its performance is verified by FE simulation.

• Transactions of the Society of Information Storage Systems
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• v.3 no.4
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• pp.191-195
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• 2007

The optical disc drive has used a high NA objective lens and a shorter wavelength laser diode for high recording density. But high NA and shorter wavelength cause several margins to become short. Focusing and tracking servo has to be more accurate and active tilt compensation mechanism is also needed for coma aberration compensation. In this paper, we proposed 3-axis moving magnet type actuator. For 3-DOF motion, moving coil actuator has to be equipped with 6 wires for supplying 3 independent signals. However, moving magnet type actuator doesn't need to change the configuration of wires because coils are in stator. So, we added a tilt mechanism to the 2-axis moving magnet actuator which is designed in previous research. Addition of the tilt mechanism cuts down the focus sensitivity. So, maximization the tilting sensitivity and securing the focusing sensitivity are objectivities of this research. DOE (design of experiments) procedures of electromagnetic circuit are performed for parameter study and the optimization is also performed to maximize the tilt sensitivity. And then the final design is suggested and its performance is verified by FE simulation.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.6
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• pp.1-5
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• 2008

As bare Fiber Bragg Grating (FBG) sensors are very fragile, bare FBG without encapsulation is not properly applied in practical infrastructures directly due to the harsh environment in practical engineering. Steel sleeve packaged FBG strain sensor is widely used in civil engineering. Since FBG senses both strain and temperature simultaneously, for accurate measurement of strain, temperature compensation for FBG strain sensors is indispensable. In this paper, based on the FBG's strain and temperature sensing principles, the temperature compensation techniques for steel sleeve packaged FBG sensors are brought forward. And the experiment of concrete early-age shrinkage monitoring by dual FBG sensors is carried out to test the feasibility of the temperature compensation technique.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.12
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• pp.1202-1209
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• 2004

This paper presents a design methodology of a Digital Servo Signal Processor for high speed CD-RW drive systems. The proposed Digital Servo Signal Processor enables us to develop CD-related systems for the very high speed applications and is one of the key components of the CD-RW systems. The proposed center compensation servo control is newly built for an actuator shaking due to the fast response of a step motor when it jumps to a long distance. A control method compensating for eccentricity of a disc is implemented for operating robustly at a higher rotational speed. This servo mechanism is more size efficient and less power consumed because it is implemented using a ARM7 embedded processor and hardware digital filters. Furthermore, it is convenient to upgrade firmware for the future required functions. From experimental results, we can see that the performance of the control system is improved greatly. The proposed servo algorithm shows a shorter setting time including a pull-in time and a faster access time. It can be applied easily to the DVD-ROM and the DVD-RAM which have the same optical structure.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.3
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• pp.275-282
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• 2013

Applications such as vibration isolation, gravity compensation, pick-and-place machines, etc., would benefit from (long-stroke) cylindrical/tubular permanent magnet (PM) actuators with integrated passive gravity compensation to minimize the power consumption. As an example, in component placing (pick-and-place) machines on printed circuit boards, passive devices allow the powerless counteraction of translator including nozzles or tooling bits. In these applications, an increasing demand is arising for high-speed actuation with high precision and bandwidth capability mainly due to the placement head being at the foundation of the motion chain, hence, a large mass of this device will result in high force/power requirements for the driving mechanism (i.e. an H-bridge with three linear permanent magnet motors placed in an H-configuration). This paper investigates a tubular actuator topology combined with passive gravity compensation. These two functionalities are separately introduced, where the combination is verified using comprehensive three dimensional (3D) finite element analyses.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.6
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• pp.7-13
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• 1999

The unbalanced heavy-loaded elevation-driving system is composed of link-mechanism, hydraulic cylinder and compensator for the static unbalanced moment of the load. Control and compensation of elevation-driving system is very difficult because these mechanisms imply highly nonlinear properties due to hydraulic fluid characteristics and mechanical rotation of link-mechanism. In this study, through the analysis of the link-mechanism, the optimal design of the link-mechanism is suggested. Also to estimate the control performance of the unbalanced, heavy-loaded servo-controlled system, modeling and simulation of nonlinear system are carried out. To prove the validity of performance estimation program, simulation results are compared with the experimental results. Both results are similar, therefore this program will be helpful to study the improvement of the system control performance.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.11
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• pp.76-82
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• 1998

In this study, the Ball screw and Servo motor Mechanism is considered as a High Speed Tool Feed System for the machining of a piston of a reciprocating engine. For the machining of a piston, that shapes oval, high speed servo mechanism is needed as a positioning of a cutting tool, and the stroke of tool is 0.1 mm ~ 1 mm. Ball screw and servo motor Mechanism is available very much because this mechanism is used widely in general machine. This Mechanism has been designed with the use of the decrease in mass and partial wear of the ball screw for high speed positioning of tool. Also the periodic learning control method with the inverse transfer function compensation has been applied to the positioning control for the high accuracy positioning of tool. These applications lead the achievement of the machining of a piston with an accuracy of 5${\mu}{\textrm}{m}$ at 2500 rpm in CNC turning.

• Management & Information Systems Review
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• v.35 no.1
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• pp.173-188
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• 2016

The introduction and operation of compensation committee can affect managers' incentive-compensation system. In this context, The purpose of this paper examines whether managers' pay-performance sensitivity is affected by the quality of the compensation committee(compensation committee size, the proportion of outside directors on the compensation committee, the proportion of directors with 2 or more non additional board seats on the compensation committee) To test this hypothesis, we use a sample of 260 firm-year observations between 2001-2013. The results are as follows. Firstly, we find that no significant relevance between the compensation committee size and pay-performance sensitivity. But the proportion of outside directors on the compensation committee and the proportion of directors with 2 or more non additional board seats on the compensation committee is positively associated with both pay-earnings based performance sensitivity and pay-stock based performance sensitivity. Secondly, we find that the integration quality of the compensation committee is positively associated with both pay-earnings based performance sensitivity and pay-stock based performance sensitivity. Overall, our analysis suggests that compensation committee are important mechanism in the design of efficient incentive-compensation system.