• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.1
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• pp.88-95
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• 2004

Micro stepping method is adopted in order to eliminate effectively the resonant phenomena and to increase the positional resolution. Exist micro-step method by using Sinusoidal waveform, drive circuit is complex by using micro controller and ROM, it have fault on cost Increase. This paper proposed trapezoidal current wave form for simple control circuit and micro stepping method by using a low cost controller. This paper proposed method verify by using CPLD(EPM9320RC208-15) of low cost. This paper make experiment that comparison of exist method and proposed method. This paper obstruct a escape of motor by using high speed detect.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.250-253
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• 2002

The operation of surface and edge finishing is the last and essential process of parts machining, because a product is completed as an assembly. Therefore, the quality of the finished parts has a direct effect upon the performance of the product. Especially, the edge quality depending on the burr control process is very important. A number of deburring processes have been developed for macro burrs such as barreling, brushing, chemical methods, etc. However, micro burr removal when piercing a very thin plate is very difficult, because this badly deteriorates the surface quality of the processed part. When ultrasonic wave is propagated in liquids, it forms an infinitude of micro bubbles. These bubbles generate extremely strong force, which removes micro burrs. In ultrasonic micro deburring, the problem is that burrs are not removed completely, because only components of the explosive force directly act on the burrs, which is not enough. An attempt was made to remove the burrs using ultrasonic vibration in water with SiC as an abrasive agent. Because of the abrasive, smoother edges have been achieved. There are many control parameters in ultrasonic deburring such as abrasive size, ultrasonic frequency and amplitude, distance between tool and workpiece, tilt angle of workpiece etc. This study focuses on how distance and tilt angle influence deburring effect. A number of experiments for these parameters have been carried out, and then the effect of each parameter analyzed.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.2
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• pp.225-231
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• 2013

Low voltage ride through capability augmentation of a hybrid micro-grid system is presented in this paper which reflects enhanced reliability in the system. The control scheme involves parallel connected multiple ac-dc bidirectional converters. When the micro-grid system is subjected to a severe voltage dip by any transient fault single power converter may not be able to provide necessary reactive power to overcome the severe voltage dip. This paper discusses the control strategy of additional power converter connected in parallel with main converter to support extra reactive power to withstand the severe voltage dip. During transient fault, when the terminal voltage crosses 90% of its pre-fault value, additional converter comes into operation. With the help of additional power converter, the micro-grid system withstands the severe voltage fulfilling the grid code requirements. This multiple converter scheme provides the micro-grid system the capability of low voltage ride through which makes the system more reliable and stable.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.5
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• pp.494-499
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• 2023

In this paper, in order to apply the CF (color filter) type of the micro light emitting device (Micro LED) display method, a study on the manufacturing process of red and green phosphor inks for the inkjet process was conducted. The blue light-emitting KSF and LuAG phosphors were respectively used to control the phosphor particle size to about 1㎛, and a phosphor ink was prepared by synthesizing with a low-viscosity solution (IPA/Eg). A chemical dispersion method was applied to selectively control the dispersion characteristics in the manufacture of phosphor inks, and in particular, phosphor inks with a dispersant applied a dispersant secured stable dispersion characteristic compared to phosphor inks without a dispersion process. Therefore, it seems possible to manufacture CF for Micro LED through an inkjet process capable of controlling the dispersion characteristics of phosphor ink.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.4
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• pp.52-59
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• 2005

When a micro hole is machined by EDM with a cylindrical electrode, the hole diameter is different at the inlet and the outlet of the micro hole. The taper shape of the micro hole is caused by not only wear of the electrode but the eroded particles. The eroded particles cause secondary discharge during machining the micro hole. As a result, the diameter of the inlet becomes larger than that of the outlet. In this paper, a new method is proposed to reduce the difference in diameter between the inlet and the outlet of the hole. Observed was that the feed depth and machining time affect the formation of taper shape On this experimental basis, ultrasonic vibration was applied to reduce machining time, and capacitance was changed during machining to use the difference in discharging energy of different capacitances. Using the proposed method, a straight micro-hole was fabricated.

• Journal of Dental Rehabilitation and Applied Science
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• v.20 no.2
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• pp.143-150
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• 2004

Endosseous implants have been used to provide anchorage control in orthodontic treatment without the need for special patient cooperation. However these implants have limitation like space requirement, cost, equipments. Recently titanium micro-implant for orthodontic anchorage was introduced. Micro-implants are small enough to place in any area of the alveolar bone, easy to implant and remove, and inexpensive. In addition, orthodontic force application can begin almost immediately after implantation. The mandibular first, maxillary first, mandibula second, and maxillary second molars were the four most commonly missing teeth in adult sample. In case of posterior molar teeth missing, deflective contacts in any position, over time, has produced pathologic change of occlusal scheme because of extrusion of opposing teeth. This case had interocclusal space deficiency by mandibular right molars missing over time. The micro-implants had been used for intrusion of maxillary right molars for interocclusal space. The micro-implant would be absolute anchorage for orthodontic movement. Therefore, the micro-implant would be effective method for correction of occlusal plane.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.9
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• pp.47-56
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• 1994

In this paper, we demonstrate how to design a redundant robot which is suitable for the multiple task execution without any constraints on the work space. The implementation is possible by the rigid connection of a cacro-robot and a micro-robot. A 5 d.o.f. articulated robor designed for commercial purpose is utilized as a micro-robot which can perform a general task with the appropriate adjustment of its base location. The base of a micro-robot is located at a suitable position by the macro-robot designed and implemented through this research. A task assigned to this redundant robot is performed mainly by the micro-robot. However, when the micro-robot cannot perform the task by itself or when the micro-robot has difficulties in performing the task, the coordination of the macro-robot is requited. To monitor the task execution efficiency of the micro-robot, we used the 'Manipulability Measure' as a cost function. The coordination between the two robots are verified both by the simulation and the experiment.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.4
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• pp.77-84
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• 2006

With the development of micro/nano spacecraft, concepts of micro propulsion are introduced for orbit transfer and drag compensation as well as attitude control. Micro solid propellant thruster has been attention as one of possible solution for micro thruster. In this paper, micro solid propellant thruster is introduced and research on basic components of a micro solid propellant thruster is reported. Micro Pt igniter was fabricated through negative patterning and quantitative effect of geometry was estimated. The characteristic of HTPB/AP solid propellant was investigated to measure the homing velocity. A combustion chamber was fabricated by means of anisotropic etching of photosensitive glass. Finally, micro solid propellant thrusters having various geometries were fabricated and tested.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.3
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• pp.12-19
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• 2006

Micro-source units having power ratings in thousands of watts can provide power quality with higher reliability and efficiency than the conventional large scale units. This paper develops switching level model of micro-source and studies the characteristics of the micro-grid consisting of multiple micro-sources and interfaced with electric power system. The developed model adopts the space vector PWM to fully utilize the capacity of inverter. The interaction of the grid connected micro-sources and the characteristics of the control system parameters are investigated. Micro-sources and micro-grid are implemented using PSCAD/EMTDC. Simulation results show that the proposed model is efficient for studying micro-grid system.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.165-168
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• 2000

This paper describes the guideline of design and tuning of practical Micro 5KVA machine's digital AVR/PSS control parameters by using the computer models and testing on-line AVR step test of laboratory simulator under the no-load or load conditions. The suggested procedures can be also applied to the large scaled machine's AVR/PSS control parameter tuning in KEPCO system.