• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.5
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• pp.496-501
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• 2009

In micro electrochemical machining(micro-ECM), it is important to measure and control the potential of a tool electrode and a workpiece electrode because electrochemical reaction rate depends on the potential of the electrodes. When the electrode potential was measured against a reference electrode, the error of measured electrode potential could be minimized by proper tool electrode design. In this paper, multi-function electrodes consisting of a tool electrode and a reference electrode was fabricated by micro fabrication techniques. The machining conditions in micro-ECM using multi-function electrodes, such as pulse voltage parameters and electrode potential, were investigated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1893-1896
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• 2003

This research aimed to fabricate a micro structure using micro electrochemical machining (${\mu}$-ECM). with a view to that the theory of ${\mu}$-ECM is established accurately in a different way of conventional electrochemical machining. In details, if the impedance is existed in the system, it is difficult to analyze the micro electrochemical reaction efficiently in polarization curve using a potentiodynamic test. Hence, this research investigates the relationships between impedance and electric current measuring with a potentiostatic test applying to a pair or electrode as a constant potential. And this paper examines the influence of temperature of electrolyte on polarization curve for the quantitative analysis of electrochemical reactions.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.3
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• pp.308-314
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• 2011

In micro electrochemical machining (micro ECM), machining conditions have been determined to maintain a small side gap and to machine a workpiece stably However, machining speed is slow. To improve machining speed while maintaining the form accuracy, the paper investigates machining parameters such as pulse amplitude, duty ratio, pulse on-time, and the electrolyte's temperature and concentration. The experiment in this study shows that the electrolyte's concentration is the key factor that can reduce machining time while maintaining the form accuracy Micro square columns were fabricated to confirm the machining parameters' effects.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.5 s.170
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• pp.37-44
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• 2005

In this paper, wire electrochemical machining (Wire ECM) with ultra short pulses is presented. Platinum wire with $10{\mu}m$ diameter was used as a tool and 304 stainless steel was locally dissolved by electrochemical machining in 0.1M $H_{2}SO_4$ electrolyte. Wire ECM can be easily applied to the fabrication of arbitrarily shaped micro-grooves without tool wear. The change of machining gap according to applied pulse voltage, pulse on-time and pulse period was investigated and the optimal pulse condition for stable machining was obtained. Using this method, various micro-grooves with less than $20{\mu}m$ width were fabricated.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.9
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• pp.1100-1106
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• 2012

This paper has presented the analysis of the micro-Doppler signatures scattered from the blades of the rotating propeller using the modified HHT method, one of the joint time-frequency analysis methods. The field scattered from the blade edge of the propeller was calculated using equivalent current method(ECM). After the acquisition of the scattered field data in the time domain, the modified HHT method was applied to analyze the micro-Doppler signature. The analysis results showed not only a good agreement with the realistic dynamic characteristic of the blade but also sinusoidally varing characteristics of the micro-Doppler signatures generated from rotating objects. It could be concluded that the joint time-frequency analysis via the modified HHT provided the discriminative characteristics for recognizing a small aircraft target with small RCS value.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.2.2-2.2
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• 2011

The central strategy in tissue engineering involves a biomaterial scaffold as a delivery carrier of cells and a depot to deliver bioactive molecules. The ability of scaffolds to control cellular response to direct particular repair and regeneration processes is essential to obtain functional tissue engineering constructs. Therefore, many efforts have been made to understand local interactions of cells with their extracellular matrix (ECM) microenvironment and exploit these interactions for designing an ideal scaffold mimicking the chemical, physiological, and structural features of native ECM. ECM is composed of a number of biomacromolecules including proteins, glycosaminoglycans, and proteoglycans, which are assembled together to form complex 3-dimensional network. Electrospinning is a process to generate highly porous 3-dimensional fibrous structure with nano to micro scaled-diameter, which can closely mimic the structure of ECM. In this presentation, our approaches to develop biomimetic electrospun fibers for modulation of cell function will be discussed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1093-1096
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• 2001

Eletrochemical phenomenon are employed in the manufacturing of micro-electrochemical machining(micro-ECM). The application of controlled electrochemical metal removal in the fabrication of microstructures and microcomponents is refer to as micro-electrochemical machining. In this paper, we introduce a new method named $\ulcorner$point-electrode electro chemical machining method$\lrcorner$ was proposed to establish micro fabrication technology by use of electrochemical machining. And we find effect of the electrochemical phenomenon in several conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.379-380
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.107-108
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.918-921
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• 2002

Some investigators who have tried to achieve the highly smooth surface finish using electrochemical processes have reported that high current density produced lustrous surfaces while the opposite conditions produced a passive layer and had a tendency to produce a black surface. However, processing at a low current density may produce a non-lustrous surface but the improvement of dimensional accuracy of the surface is significant. The surface with pulse process was a bit more lustrous than with continuous current but the black passive layer still could be found at grooved surface. There are two ways to achieve highly smooth surface finish. One is brushing it with a brush the other is electrochemical machining (ECM) with high current. The former method is the most common polishing practice, but not only may the surface obtained differ from operator to operator, but precision smooth surface on micro grooves are difficult to obtain. The latter one recently has been used to produce a highly smooth surface after EDM process. However, the material removal rate in ECM with high current is relatively high. Hence the original shape of the micro grooves, which was formed by electrochemical micro-machining (EMM) process, may be destroyed. In this study, an electrochemical polishing process using pulse current is adopted as a possible alternative process when micro grooves formed by EMM process should be polished. Mirror-like micro grooves with lustrous and smooth surface can be produced electrochemically with pulse current because the voltage and current used can be lower than the case of continuous current. This study will discuss the accurate control of physical and electrical conditions so as to achieve mirror-like micro grooves with lustrous and smooth surface without destroying the original shape of micro grooves.