• 전기의세계
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• v.49 no.2
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• pp.6-11
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• 2000

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.91.2-91.2
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• 2005

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.389-394
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• 2005

Microfactory is effective method for machining micro size component. Electro-chemical machining can be more suitable to a microfactory than other machining methods in terms of maintaining high accuracy. Surface profile of EDM Machined component is predicted by micro EDM simulation using superpositioning spark crater. Planar motor and micro pump are developed to construct microfactory system.

• Polymer(Korea)
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• v.32 no.4
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• pp.334-339
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• 2008

Recently electro spinning is a widely used simple technique to prepared micro- to nanometer-sized fiber of various polymers. In general, a normal multiple-nozzle electro spinning system has been difficult to achieve high production-rate fabricating micro/nanofibers due to the interference of electric field between individual nozzles in the process. To reduce the interference effect of electric field between nozzles, we developed a multi-nozzle electrospinning system supplemented with auxiliary electrodes. Poly($\varepsilon$-carprolactone)(PCL), which has good mechanical property and biocompatibility, was electrospun by the multi-nozzle electro spinning system. Electrospinnability, product rate, and size uniformity of spun fibers for the system with and without auxiliary electrodes were characterized. As a result, the multi-nozzle electrospinning system supplemented with auxiliary electrodes provides excellently stable processability and showed high mass productivity of PCL-nanofibers relative to a normal multi-nozzle electro spinning system.

• Structural Engineering and Mechanics
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• v.72 no.1
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• pp.113-129
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• 2019

A four-variable shear deformation refined plate theory has been proposed for dynamic characteristics of smart plates made of porous magneto-electro-elastic functionally graded (MEE-FG) materials with various boundary conditions by using an analytical method. Magneto-electro-elastic properties of FGM plate are supposed to vary through the thickness direction and are estimated through the modified power-law rule in which the porosities with even and uneven type are approximated. Pores possibly occur inside functionally graded materials (FGMs) due the result of technical problems that lead to creation of micro-voids in these materials. The variation of pores along the thickness direction influences the mechanical properties. The governing differential equations and boundary conditions of embedded porous FGM plate under magneto-electrical field are derived through Hamilton's principle based on a four-variable tangential-exponential refined theory which avoids the use of shear correction factors. An analytical solution procedure is used to achieve the natural frequencies of embedded porous FG plate supposed to magneto-electrical field with various boundary condition. A parametric study is led to carry out the effects of material graduation exponent, coefficient of porosity, magnetic potential, electric voltage, elastic foundation parameters, various boundary conditions and plate side-to-thickness ratio on natural frequencies of the porous MEE-FG plate. It is concluded that these parameters play significant roles on the dynamic behavior of porous MEE-FG plates. Presented numerical results can serve as benchmarks for future analyses of MEE-FG plates with porosity phases.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.2
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• pp.153-160
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• 2019

Electro-mechanical actuator system for aircraft has advantages in compactness and its lightweight, compared to the hydraulic actuator system. Hinge line actuator has low air resistance and is suitable for special purpose such as stealth. This paper describes design contents of 10,000 lbf-in class dual redundant hinge line electro-mechanical actuator system for performance test. The control structure was designed to minimize impact of torque fighting. A mathematical model is proposed to analyze and validate the performances of actuator by comparison with experiment results.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.2
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• pp.89-96
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• 2000

This paper describes the characteristic of die finishing to obtain smooth surface using electro-chemical grinding after cutting process. Electro-chemical grinding is possible under lower load and tool wear comparing with those in the mechanical grinding. Conventionally, if the metal bonding material of the grinding wheel is directly t contacted with workpiece, the current is circulated without electrolytic phenomena. Sometimes, electrical discharge is occurred between tool and workpiece. To cope with this problem, the metal-resin bonded pellet was used in this study. This pellet is composed of optimal volume of metal and resin powders and its characteristics are changable with the each volume of powders. Finally, high efficient die finishing is realized using metal resin bonded pellet in electro-chemical grinding.

• Journal of Biosystems Engineering
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• v.17 no.3
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• pp.223-228
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• 1992

This study was conducted to develop an electro-hydraulic three-point hitch control system using an electro-hydraulic servo valve and microcomputer and to investigate the performance of the three-point hitch control system through indoor and field experiments. 1. The results from indoor experiments coincided with those from computer simulation reported in the previous paper. However, the draft control with the value 4 of Kd showed a slight sustained oscillation after it reached the draft set. 2. From the field experiments, it appeared that the RMS errors increased with the ground speed of tractor. In position control, the three-point hitch control system with electro-hydraulic servo valve showed better performance than that with on-off electro-magnetic valve in the ground speed less than 1.6 m/s. In draft control, however, there was no significant differece in performance between those two systems. 3. In depth control, the both types of electro-hydraulic three-point hitch control system showed better performance than the conventional mechanical-hydraulic three-point hitch control system.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.1
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• pp.66-71
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• 2014

In this research, a material test machine is developed which uses a small electro-magnetic actuator and a leverage mechanism. The leverage mechanism amplifies the force from the electro-magnetic actuator. The electro-magnetic part operates more silently and cleanly than a hydraulic part. In a tooth material study, a test machine does not require a large force capacity because it handles only $4mm^2$-sectioned and short-span specimens. Conventional test machines such as those by Instron and the BOSE Enduratec ELF3200 have too high aforce capacity for a tooth material study. A test machine for a tooth material study requires an acting force only on the order of tens of Newtons (N) operating at several Hertz.

• Tribology and Lubricants
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• v.34 no.2
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• pp.55-59
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• 2018

This paper proposes a new type of electro-mechanical wedge brake for commercial vehicles. The brake operates on a novel mechanism for self-boosting braking friction forces using eccentric shafts, and involves wedges that are inserted between the rampbridge and traverse; this self-boosting mechanism is explained herein. A dynamic analysis using ADAMS was conducted, and the findings are reported. The constraint and contact conditions are explained to verify the precision of the dynamic analysis. The dynamic analysis shows that in the proposed mechanism, the self-boosting effect occurs as desired. However, it is also noted that the system has a limitation in terms of the production of unlimited braking forces that can jam the roller inside the wedges. After demonstrating the self-boosting effect, dynamic analyses are performed for several values of the wedge angles and friction coefficients between the brake pads and disks. Conventionally, a lower wedge angle has been suggested owing to its provision of a larger clamping force for given friction coefficients. However, it is noted that lower wedge angles can lead to a higher probability of occurrence of undesirable high braking forces, which can jam the roller into the wedge; thus, a larger wedge angle is preferable for avoiding the undesirable jamming phenomena. These analysis results are presented and discussed herein.