• Journal of the Korean Society for Precision Engineering
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• v.19 no.12
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• pp.134-141
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• 2002

The ER fluid can be one of efficient materials in ultraprecision polishing for optics, ceramics and semiconductors because of electrically controllable apparent viscosity. To finish small 3 dimensional structures such as the aspherical surface in optical elements, the possible arrangement of a tool, workpiece and auxiliary electrode is described. We examined the influence of the addition of a few abrasive particles on the performance of the ER fluid by measuring yield stress, and observed the behavior of abrasive particles in the ER fluid by a CCD camera, which is also theoretically predicted from the electromechanical principles of particles. On the basis of the above results, the steady flow analysis around the rotating micro tool is worked out considering the non-uniform electric field. Finally, Pyrex glass is polished using the mixture of the ER fluid and abrasive particles, and the effect of the electric field strength is evaluated.

• Transactions on Electrical and Electronic Materials
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• v.11 no.5
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• pp.216-221
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• 2010

The microstructure, electrical properties, and DC-accelerated aging behavior of the Zn-Pr-Co-Cr-Y-Er (ZPCC-YE) varistors were investigated for different amounts of erbium oxide ($Er_2O_3$). The microstructure consisted of zinc oxide grain and an intergranular layer ($Pr_6O_{11}$, $Y_2O_3$, and $Er_2O_3$-rich phase) as a secondary phase. The increase of $Er_2O_3$ amount decreased the average grain size and increased the sintered density. As the $Er_2O_3$ amount increased, the breakdown field increased from 5094 V/cm to 6966 V/cm and the nonlinear coefficient increased from 27.8 to 45.1. The ZPCC-YE varistors added with 0.5 to 1.0 mol% $Er_2O_3$ are appropriate for high voltage, with high nonlinearity and stability against DC-accelerated aging stress.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.3
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• pp.434-440
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• 2004

The electro-rheological fluids for semi-active suspension system are a class of colloidal dispersion which exhibit large reversible changes in their rheological behavior when they are subjected to external electrical fields. This paper presents Bingham properties of ER fluids subjected to temperature variations. In addition, an appropriate size of the ER damper for a passenger car is proposed to investigate the effects of Bingham characteristics on the damping performance. The filed-dependent damping forces are evaluated according to the temperature variation and sedimentation ratio.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.850-853
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• 2000

It is well-known that Electro-rheological(ER) fluid is a material(suspension) which shows the dramatic change of rheological properties under an electric field. Using these properties, the concept that variable apparent viscosity of ER fluid could be applicable to the polishing for micro parts was introduced. It was investigated that how it works for polishing and how it affects ER effect when abrasives were mixed with an ER fluid. Therefore a few structures for polishing using ER fluid was suggested and evaluated by means of experiments. In this paper, fundamental mechanism and experimental results are described.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.11-17
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• 2011

In this paper, we propose ER_Modeler, which is a logical database design tool based on entity-relationship model. ER_Modeler provides the entity-relationship diagrams to be built graphically on windows and generates the graphs into the appropriate data definition language for creating relational database tables. Furthermore, ER_Modeler provides the import/export functions using XML to guarantee the interoperability with ERwin which is one of the most popular commercial products.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.481-486
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• 2000

This paper presents vibration control performance of a passenger vehicle installed with olectro-rheological(ER) engine mounts. As a first step, a mixed-mode ER engine mount is modeled and manufactured. After verifying the controllability of the dynamic stiffness by the intensity of the electric field, ER engine mounts are incorporated with a full-car model. The governing equation of motion is then formulated by considering engine excitation force. A skyhook controller to attenuate vibration motions is designed. The controller is implemented through hardware-in-the-loop simulation and control responses are presented in the both frequency and time domains.

• BMB Reports
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• v.31 no.2
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• pp.196-200
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• 1998

Zeins, maize storage proteins, are retained in the endoplasmic reticulum (ER) during the subcellular targeting process without the ER retention signal. Circumstantial data indicate that the 27K zein is an ER transmembrane protein. The potential transmembrane domain may permit the 27K zein to remain in the ER. This study investigated the potential transmembrane feature by employing alkaline extraction, proteinase K digestion, and surface biotinylation on isolated intact protein bodies. These assays consistently support the possibility of the 27K zein as a transmembrane protein. The 27K zein polypeptide was shown to be associated with alkali-stripped membranes. The polypeptide was digested by proteinase K to a smaller fragment. According to surface biotinylation, the 27K zeins was labeled to the exclusion of other classes of zeins. This study, therefore, concludes that the 27K zein has an ER transmembrane domain, which may serve as an anchor for zeins' ER retention.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.5
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• pp.49-54
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• 2005

An experimental Investigation was performed to study the characteristics of Electro-Rheological fluid flow in a horizontal rectangular tube with or without D.C electric field control. First, the microscopic behavior of the ER suspension structure between rectangular tube brass electrodes for the stationary ER nut(i and flow of the ER fluid was investigated by flow visualization. The flow of the ER fluid between fluid rectangular tube was solved experimental using the constitutive equation for a Bingham fluid. ER fluid is made silicon oil mixed with $0.2wt\%$ starch having hydrous particles. Velocity distributions of the ER fluids were obtained by particle image velocimetry measuring those of the clusters using an image processing technique.

• Korean Journal of Materials Research
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• v.16 no.1
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• pp.58-62
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• 2006

Effects of doping concentration and annealing atmosphere on the luminescent properties of $Er^{3+}$ doped ZnO phosphor powders were investigated. Photoluminescence (PL) spectra of ZnO:Er exhibit an orange emission band at around 575 nm, while those of pure ZnO show a green emission at 520 nm. Emission difference between ZnO:Er and pure ZnO is attributed to the energy transfer of Er ions in ZnO. The highest PL intensity is obtained by doping 1 mol% Er to ZnO. Luminescent properties of ZnO:Er phosphors annealed at $N_2$+vacuum atmosphere are superior to those annealed at $N_2$ atmosphere.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.69-77
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• 1995

This paper presents performance investigation of a continuously variable ER(Electro-Rheological) damper for passenger vehicles. A dynamic model of the damper is formulated by incorporating electric field-dependent Bingham properties of the ER fluid. The Bingham properties are experimentally obtained through Couette type electroviscous measurement with respect to two different particle concentrations. The governing equation of the hydraulic model treating three components of fluid resistances;electrode duct flow, check valve flow and piston gap flow, is achieved via the bond graph method. A prototype ER damper is then designed and manufactured on the basis of parameter analysis. The damping forces of the system are experimentally evaluated by changing the intensity of the electric field, the particle concentration and the electrode gap.