• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.685-686
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• 2009

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.6
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• pp.3-9
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• 2013

Aluminum Oxide($Al_2O_3$) ceramics are excellent candidates for such applications due to their outstanding mechanical, thermal, and tribological properties. However, they are difficult to machine using conventional mechanical methods. Carbon fillers, such as carbon nanotubes(CNT) and graphene nanoplatelets(GNP)can be dispersed in a ceramic matrix to improve the mechanical and electrical properties. In this study, CNT and Graphene reinforced hybrid ceramic composites were fabricated using the spark plasma sintering method at a temperature of $1,500^{\circ}C$, pressure of 40 MPa, and soaking time of 10min. Besides this, the material properties such as microstructure, crystal structure, hardness, and electrical conductivity were analyzed using FE-SEM, XRD, Vickers, and the 4-point probe method. A micro machining test was carried out to compare the effects of the material properties and the machining performance for CNT and Graphene reinforced ceramic composites.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.9
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• pp.967-972
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• 2014

The good light permeability and hardness of glass allow it to be used in various fields. Non-conventional machining methods have been used for glass machining because of its brittle properties. As one non-contact machining method, a laser has advantages that include a high machining speed and the fact that no tool making is required. However, glass has light permeability. Thus, the use of a laser to machine glass has limitations. A nanosecond pulse laser can be used at low power for laser-induced backside wet etching, which is an indirect method. In previous studies, a short-wave laser that had good light absorption but a high price was used. In this study, a near-infrared laser was used to test the possibility of glass micro-machining. In particular, when deeper machining was conducted on a glass structure, more problems could result. To solve these problems, microstructure manufacturing was conducted using ultrasonic vibration.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.313-317
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• 2003

Micro-Channel ultra-precision polishing is a new technology used in magnetic field-assisted relishing. In this paper, an electromagnet or the i18 of test system was designed and manufactured. A size of magnetic abrasive is used on 25~75${\mu}{\textrm}{m}$ and for the polish a micro-channel upper part. A surface of channel which is not even is manufactured using magnetic abrasive finishing at upper surface of micro-channel. As a result, the surface roughness rose by 80％ after upper surface of micro- channel was polished up 8 minutes by polishing.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1482-1483
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• 2008

This report describes the design, fabrication and experimental results of an implantable micro pressure regulator. It consists of three silicon substrates, a glass substrate, and a PDMS layer. Silicon and glass substrates are fabricated by using bulk micro machining and sandblasting. The PDMS layer is used as a intermediate layer for Si-Si and Si-glass bonding processes. This micro regulator is a key component of the portable drug delivery systems for low power consumption. The device has some advantages, such as a passive type device, no power consumption, and simple structure.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.8 s.185
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• pp.163-170
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• 2006

By removing sacrificial layer through ashing process, movable MEMS structure on substrate can be fabricated in surface micromachining. However, MEMS structure includes, during the ashing process, the warping or buckling effects due to stress gradient along the vertical direction of thin film. In this study, we presented method for counteracting the unwanted deflection of MEMS structure and designed using character of deposit process to overcome limited design conditions. Unit cell patterns were designed with character of deposit shape, and their final shapes were adopted using Finite Element Method. Finally, RF MEMS switch was fabricated by surface micro machining as test vehicles. We checked out that alleviation effect for deformation of switch improved by 35%.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.282-285
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• 2009

Ignition Safe-Arm-Unit using micro-electromechanical systems(MEMS) for propulsion system was designed and manufactured. MEMS was designed according to the design schemes for conventional mechanical elements. By comparing the design results and the test data of the prototype, small discrepancy was found, which is due to the nonlinear characteristic of the structure and the machining accuracy. The applicability of MEMS for Safe-Arm-Unit was proved by testing MEMS which is assembled into SAU.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.3 s.192
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• pp.108-116
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• 2007

To overcome many defects such as the high product cost, large energy consumption, and big space capacity in conventional mechanical machining, the miniaturization of machine tool and micro factory systems has been envisioned recently. The object of this paper is to research the effect of dynamic characteristic parameters in bolted-joint beams, which is widely applied to the joining of mechanical structures in order to identify structural system characteristics and to predict dynamic behavior according to scale-down from macro to micro system as the development of micro/meso-scale machine tool and micro factories. Modal parameters such as the natural frequency, damping ratio, and mode shape from modal testing and dynamic characteristics from finite element analysis are extracted with all 12 test beam models by materials, by size, and by joining condition, and then the results obtained by both methods are compared.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.820-823
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• 2002

MEMS structures Generally have been fabricated using surface-machining, but the interface failure between silicon substrate and evaporated thin film frequently takes place due to difference of linear coefficient of thermal expansion. Therefore this paper studied the effect of the residual stress caused by variable external loads. This study did not analyzed accurate quantity of the residual stress but trend for the effect of residual stress. Several specimens were fabricated using other material(Al, Au and Cu) and thermal load was applied. The residual stress was measured by nano-indentation using AFM. The results showed the existence of the residual stress due to thermal load. The indentation area of the thermal loaded thin film reduced about 3.5% comparing with the virgin thin film caused by residual stress. The finite element analysis results are similar to indentation test.