• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.748-753
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• 2000

Nowadays, many studies and researches in data storage have been carried out and storage capacity is increased. But the limitation of storage capacity is happened for several problems. One of them is spot & pit size in optical and magnetic data storage and another is the resolution of actuators. The problems in spot & pit size is covered by new data storage methods- for example, NFR{Near-Field Recoding) system. But the resolution limit of an actuator doesn't follow up the development of spot & pit size. Because of them, we should improve a resolution of an actuator. Especially, in this paper an actuator is studied and designed for NFR(in using SIL(Solid Immersion Lens) system. It is a dual stage actuator, which consists of a Fine actuator and a Coarse actuator, and should desire 100nm accuracy. But, our actuator system only includes tracking mechanism execpt focusing mechanism which is controlled by slider mechanism used in HDD. Its actuating force generation method is VCM(Voice Coil Motor). The Fine actuator is composed of 4-leaf springs and a bobbin wrapped by coil. The Coarse actuator has Coils and 3-Roller bearings.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.4
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• pp.3-9
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• 2007

Existing long range piezoelectric motors with friction based transmission mechanisms are limited by the axial load capacity. To overcome this problem, a new linear piezoelectric motor using one piezoelectric actuator combined with a novel stepping mechanism is reported in this paper. To obtain both long range and fine accuracy, dual positioning control strategy consisting of coarse positioning and fine positioning is used. Coarse positioning is used for long travel range by accumulating motion steps obtained by piezoelectric actuator. This is followed by fine positioning where required accuracy is obtained by fine motion displacement of piezoelectric actuator. This prototype is able to provide resolution of 20 nanometers and withstand a maximum axial load of 300N. At maximum load condition, the positioner can move forward to a travel distance of 5mm at a maximum speed of 0.4 mm/sec. This design of nanopositioner can be used in applications for ultra precision positioning and grinding operations where high axial force capacity is required.

• Animal cells and systems
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• v.6 no.4
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• pp.327-333
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• 2002

Among the silk glands in the black widow spider Latrodectus mactans, the ampullate one is the most predominant gland in both sexes, and is com-posed of three functional parts - excretory duct, storage ampulla and convoluted tail regions. This experiment was performed using mechanical pulling stimulation with electric motor equipment to reveal a correlation between silk usage and silk producing system in this poisonous spider. The mature secretory products in glandular epithelium are closely packed and appear as electron-opaque spherical vesicles. A part of the vesicles with fine fibrillar paracrystalline texture seems to store some proteins which will function at the time of final assembly into fibrils. Most of the secretory silk products which originated from the rough endoplasmic reticula of the glandular epithelial cells are grown by fusion with surrounding small vesi-cles. However, the Golgi complex does not seem to play an important role in this process of secretion. According to progressive maturation of secre-tory silk product, these granules are progressively filled with a fine fibrillar material, and thus appear much more electron-dense than those of earlier states. When the secretory product is extruded from the glandular cavity, the epithelium is rapidly changed to a thinner layer of tall columnar cells with less definitive cell membranes. After extruding there ave a few secre-tory droplets within these cells, thus causing this region to stain much lighter.

• Journal of Families and Better Life
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• v.31 no.1
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• pp.11-27
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• 2013

The purpose of this study was to investigate the overall developmental characteristics of Korean children ages 0 to 8, and then explore specifically how children's social and emotional developmental levels are related to mothers' psychological states. This study was part of newly launched Boryung Baby Panel Study using web-based survey in 2011. The subjects were all mothers of 940 infants(0-2 years), 654 toddlers(3-5 years), and 484 school-age children(6-8 years) The mothers were asked to administer the web-based standardized developmental checklist for their child and fill out the questionnaires of psychological variables(life satisfaction, depression, parenting attitude, parenting efficacy, and parenting stress). The data was analyzed using descriptive analysis, t-test, and logistic regression for SPSS 20.0 windows. Major findings were as follows: 1. Infants(0 to 2) showed higher developmental level in cognition and fine motor skill domain compared to other domains. 2. Most toddlers(3 to 5) showed normal development in the most domain such as gross motor skill, fine motor skill, language, letter, number, self-help behavior. 3. In socio-emotional development domain, the ratio of risk or delay group were highest at both infant and toddler. 4. The 6-8 years old children that belong to risk group by the result of SDQ(emotion and behavior assessment) were also relatively high. 5. The relation of the children's socio-emotional developmental level and the mother's psychological variables were reciprocal. Based on these findings, the implications and the limitations of current study were discussed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.10
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• pp.997-1005
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• 2008

Linear motor stage is a useful device in precision engineering field because of its simple power transmission mechanism and accurate positioning. Even though linear motor stage shows fine positioning accuracy along travel axis, geometric dependent errors which relay on machining and assembling accuracy should be addressed to increase total positioning performances. In this paper, we suggests a cost effective yaw error compensation servo-system which is mounted on platform of the stage and nullify travel position dependent yaw error. This paper also provides a method of designing a sliding mode control which is robust to existing friction disturbance and model uncertainties. The reachability condition of slinding mode control for the yaw error compensating servo-system has been established. From some experimental results by using an experimental set-up, the sliding mode control showed its effective in disturbance rejection and its performance was superior to conventional linear controls.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.3
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• pp.240-248
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• 1999

This paper presents the application of fuzzy algorithm for speed control of Switched Reluctance Motor. SRM has a h highly nonlinear control characteristic and operates in saturation to maximize the motor torque. A systematic approach t to the modeling of highly nonlinear SRM drive system which includes the fuzzy controller with coarse control and fine C control is presented. PelfOlmance analysis of SRM dJive is reported for a wide range of operating conditions through s speed variation and load perturbation dynamics. The pelfOlmance indices of SRM drive system operating with fuzzy 1 logic controller are compared with the conventional controller to highlight the merits. The expel1mental results are p presented to confilm the validity of proposed fuzzy 10밍c controller.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.754-758
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• 2000

In recent years, the LDM(Linear DC Motor) is widely used, because it has more merits than other rotary motors. First, if system requires linear motion, LDM realizes direct linear motion as rotary motor does not. Second, system is simple and easy to control, and so on. In optical disc drive, a tracking system consists of two parts. One is fine actuating and the other is coarse actuating. For coarse actuating VCM(Voice Coil Motor) actuator is used as a basic drive mechanism. In this paper, MC(Moving Coil) type LDM is designed, manufactured and controlled. System is composed of mechanical-electromagnetic component, therefore mechanical loss and electromagnetic loss exist. The dominent mechanical loss is friction which results from sliding between guide shaft and hole. Therefore, this paper shows the friction compensation control. High speed and accurate position is not gained only PID control, therefore other control method is applied to the system.

• Journal of the Korean Society for Precision Engineering
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• v.2 no.1
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• pp.72-81
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• 1985

This paper deals with the Z-8000 microprocessor based optimal controller problem of large rotating system. Control algorithm consists of Global Mode and Fine Mode. In Global Mode, motor is driven with maximum torque, while, in Fine Mode, the speed of response and overshoot improved by multi-gains. Friction term of the plant was measured in the 1-st test, jerking effect by the nonlinearity of friction was compensated in the 2-nd test and the 3-rd test was carried out to finalize the control system model. Test results show that the speed of response and overshoot are highly improved.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.90-94
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• 1992

A portable multichannel functional electrical stimulation(FES) system for the fine control of the paralyzed extremities in spinal cord injury patients is described. This system is composed of a stimulation data creating system, a serial communication device, a 16-bit microprocessor, D/A converter of 32 channels and a display device. Stimulation patterns are created from analytical results of integrated EMGs during motion in normal subjects and are stored in the stimulation data creating system as data files. And then the stimulation patterns are sent to the memory in the portable multichannel FES system through serial communication interfacing device. Sophisticated fine control of paralyzed extrimities was realized by transmitting multichannel stimulation patterns to percutaneous intramuscular electrodes, which stimulate the motor function of paralyzed muscle simultaneously. Advantages of this system are as follws: 1) It is possible to modify stimulation patterns in accordance with the patient's situation. 2) This system is small and light.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.220-225
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• 2003

Recent issue of optical actuator is applying to mobile device. It leads actuator to become smaller than conventional type. This paper proposes the design of micro actuator plate spring and analysis of its vibration characteristic. Considering natural frequency of spindle motor, 1st and 2nd eigenfrequency of micro actuator must avoid its natural frequency. First, magnetic circuit is designed by using fine pattern coil and magnetic force is acquired by simulation program. Then, concept design is achieved by topology optimization. From concept design, micro actuator plate spring is embodied through DOE(design of experiment). Finally, considering vibration characteristic simultaneously, optimal plate spring design is determined by RSM(response surface method).