• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.4
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• pp.524-530
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• 2002

Micro electric spark discharge device was fabricated on a FOTURAN glass wafer using MEMS processing technique and its performance of electron discharge and subsequent formation of ignition kernel were tested. Micro electric spark device is an essential subsystem of a power MEMS that has been under development in this laboratories. In a combustion chamber of sub millimeter scale depth, spark electrodes are formed by electroplating Ni on a base plate of FOTURAN glass wafer. Optimization of spark voltage and spark gap is crucial for stable ignition and endurance of the electrodes. Namely, wider spark gaps insures stable ignition but requires higher ignition voltage to overcome the spark barrier. Also, electron discharge across larger voltage tends to erode the electrodes limiting the endurance of the overall system. In the present study, the discharge characteristics of the proptotype ignition device was measured in terms of electric quantities such as voltage and currant with spark gap and end shape as parameters. Discharge voltage shows a little decrease in width of less than 50㎛ and increases with electrode gap size. Reliability test shows no severe damage over 10$\^$6/ times of discharge test resulting in satisfactory performance for application to proposed power MEMS devices.

• Journal of Sensor Science and Technology
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• v.12 no.6
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• pp.265-272
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• 2003

This paper describes anodic bonding characteristics of MLCA (Multi Layer Ceramic Actuator) to Si-wafer using evaporated Pyrex #7740 glass thin-films for MEMS applications. Pyrex #7740 glass thin-films with same properties were deposited on MLCA under optimum RF magneto conditions(Ar 100%, input power $1\;W/cm^2$). After annealing in $450^{\circ}C$ for 1 hr, the anodic bonding of MLCA and Si-wafer was successfully performed at 600 V, $400^{\circ}C$ in - 760 mmHg. Then, the MLCA/Si bonded interface and fabricated Si diaphragm deflection characteristics were analyzed through the actuation test. It is possible to control with accurate deflection of Si diaphragm according to its geometries and its maximum non-linearity is 0.05-0.08 %FS. Moreover, any damages or separation of MLCA/Si bonded interfaces do not occur during actuation test. Therefore, it is expected that anodic bonding technology of MLCA/Si wafers could be usefully applied for the fabrication process of high-performance piezoelectric MEMS devices.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.12
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• pp.1292-1299
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• 2003

In this paper, we fabricated new GaAs-based dielectric-supported air gapped microstriplines(DAMLs) using the surface MEMS and the LPF for Ka-band using the fabricated DAMLs. We elevated the signal lines from the substrate, in order to reduce the substrate dielectric loss and obtain low losses at millimeter-wave frequency band with wide impedance range. We fabricated LPF with DAMLs for Ka-band. Due to reducing the dielectric loss of DAMLs, the insertion loss of LPF can be reduced. Miniature is essential to integrate LPF with active devices, so that we fabricated LPF with the slot on the ground to reduce the size of the LPF. We compared a characteristic to LPF with the slot and LPF without the slot.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.551-552
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• 2006

The miniature fuel cells have emerged as a promising power source for applications such as cellular phones, small digital devices, and autonomous sensors to embedded monitors or to micro-electro mechanical system (MEMS) devices. Several chemicals run candidate at a fuel in those systems, such as hydrogen. methanol, ethanol, acetic acid, and di-methyl ether (DME). Among them, hydrogen shows most efficient fuel performance. However, there are some difficulties in practical application for portable power sources. Therefore, more recently, there have been many efforts for development of micro-reformer to operate highly efficient micro fuel cells with liquid fuels such as methanol, ethanol, and DME In our experiments, we have integrated a micro-fuel processor system using low temperature co-fired ceramics (LTCC) materials. Our integrated micro-fuel processor system is containing embedded heaters, cavities, and 3D structures of micro- channels within LTCC layers for embedding catalysts (cf. Figs. 1 and 2). In the micro-channels of LTCC, we have loaded $CuO/ZnO/Al_2O_3$ catalysts using several different coating methods such as powder packing or spraying, dipping, and washing of catalyst slurry.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.528-531
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• 2000

Deposition of PZT with UV laser ablatio was applied for realization of thin film sensors and actuators. Deposition rate of more than 20nm/min was attained by pulsed KrF excimer laser deposition, which is fairly better than those obtained by the other methods. Perovskite phase was obtained at room temperature deposition with Fast Atom Beam(FAB) treatment and annealing. Smart MEMS(Micro electro-mechanical system) is now a suject of interest in the field of micro optical devices, micro pumps, AFM cantilever devices etc. It can be fabricated by deposition of PZT thin films and micromachining. PZT films of more than 1 micron thickness is difficult to obtain by conventional methods. This is the reason why we applied excimer laser ablation for thin film deposition. The remanent polarization Pr of 700nm PZT thin film was measured, and the relative dielectric constant was determined to about 900 and the dielectric loss tangent was also measured to be about 0.04. XRD analysis shows that, after annealing at 650 degrees C in 1 hour, the perovskite structure would be formed with some amount of pyrochlore phase, as is the case of the annealing at 750 degrees C in 1 hour.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.582-587
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• 2002

Current information storage devices, such as HDD, CD/DVD-ROM/RW, probe-based memory and hologram memory, are compared with biological information storage mechanisms in DNA and brain memory. Newly developed approaches to overcome the limit of storage capacity are introduced in both magnetic and optical recording devices. Linear and areal density of information stored in the biological and mechanical storages are compared for the applications and developments of new storage devices.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.630-633
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• 2021

Microphones can convert received voice signals to electric signals. They have been widely used in various industries such as radios, smart devices and vehicles. Recently, the demands for small size and high sensitive microphones are increased according to the minimization of wireless earphone with the development of smart phone. A MEMS system is a good candidate for an ultra-small size microphone of a next generation and a read out IC for high sensitive MEMS sensor is researched from many industries and academies. Since the microphone system has a high sensitivity from environment noise and electric system noise, the system requires a low noise power supply and some low noise design techniques. In this paper, a low noise LDO is presented for small size MEMS microphone systems. The input supply voltage of the LDO is 1.5-3.6V, and the output voltage is 1.3V. Then, it can support to 5mA in the light load condition. The integrated output noise of proposed LDO form 20Hz to 20kHz is about 1.9uV. These post layout simulation results are performed with TSMC 0.18um CMOS technology and the size of layout is 325㎛ × 165㎛.

• Transactions on Electrical and Electronic Materials
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• v.17 no.3
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• pp.150-154
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• 2016

Contact electrodes pose threats like inflammation, metal poisoning, and allergic reaction to the user during long term ECG procedure. Therefore, we present a novel noncontact electrocardiographic electrode designed through microelectromechanical systems (MEMS) process. The proposed ECG electrode consists of small inner and large outer circular copper plates separated by thin insulator. The inner plate enables capacitive transduction of bio-potential variations on a subject’s chest into a voltage that can be processed by a signal processing board, whereas the outer plate shields the inner plate from environmental electromagnetic noise. The electrode lead wires are also coaxially designed to prevent cables from coupling to ground or electronic devices. A prototype ECG electrode has an area of about 2.324 cm², is very flexible and does not require power to operate. The prototype ECG electrode could measure ECG at about 500 um distance from the subject’s chest.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.1
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• pp.11-15
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• 2001

We present the design and strength evaluation of an anodically bonded pressurized cavity array, based on the energy release rate measured from the anodically bonded plates of two dissimilar materials. From a theoretical analysis, a simple fracture mechanics model of the pressurized cavity array has been developed. The energy release rate (ERR) of the bonded cavity with an infinite bonding length has been derived in terms of cavity pressure, cavity size, bonding length, plate size and material properties. The ERR with a finite bonding length has been evaluated from the finite element analysis performed for varying cavity and plate sizes. It is found that, for an inter-cavity bonding length greater than the half of the cavity length, the bonding strength of cavity array approaches to that of the infinite plate. For a shorter bonding length, however, the bonding strength of the cavity array is monotonically decreased with the ratio of the bonding length to the cavity length. The critical ERR of 6.21J/㎡ has been measured from anodically bonded silicon-glass plates. A set of critical pressure curves has been generated for varying cavity array sizes, and a design method of the pressurized cavity array has been developed for the failure-free wafer-level packaging of MEMS devices.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.1
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• pp.1-6
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• 2011

We have developed the process of forming one body S-type cantilever probe in the recessed trench for fine-pitched MEMS probe card. The probe (cantilever beam and pyramid tip) was formed using Deep RIE etching and wet etching. The pyramid tip was formed by the wet etching using KOH and TMAH. The process of forming the curved probe was also developed by the wet etching. Therefore, the fabricated probe is applicable for the probe card for DRAM, Flash memory and RF devices tests and probe tip for IC test socket.