• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2008.03a
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• pp.169-184
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• 2008

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1544-1545
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• 2007

본 논문은 피에조방식으로 구동하는 MEMS 구조의 산업용 잉크젯 헤드를 제작하여 잉크를 충진하여 토출하는 과정에서 토출이 되지 않는 원인 중 하나인 기포에 대해서 연구하였다. 기포를 직접 관찰하기 위한 방법으로 투명한 유리로 Membrane을 제작하여 기포가 발생하여 거동하는 모습을 관찰하였으며 Actuator가 구동하는 헤드내 기포를 구동 중에 관찰하기 위한 방법으로 LDV(Laser Doffler Vibrometer)를 이용하였다. 그 결과, 구동하면서 발생하는 변위의 미세한 차이를 관찰할 수 있었으며 주파수 data의 차이를 관찰함으로써 기포의 크기에 따른 토출의 양태를 구별할 수 있었다.

• Journal of Drive and Control
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• v.10 no.1
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• pp.29-36
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• 2013

Excavation is an important work in mining, earth removal and general earthworks. Nowadays, automation in excavator has been studied by several researchers. In the excavator research methods, simulation is one of the low cost methods for applied to test safely. In this paper, designed a virtual hydraulic excavator that with the control and the dynamic. At first, the simulation of hydraulic system for excavator's attachment such as boom, arm and bucket using Matlab/Simhydraulic is presented. Second, the dynamic model of excavator is distributed to combine with the hydraulic system. For controlling this system, electric joysticks are used to operate the orifice open areas in Main Control Valve. The simulation result is described to analysis the performance of this virtual excavator.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1550-1551
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• 2007

노즐 직경 $30\;{\mu}$인 MEMS 압전 잉크젯 헤드를 이용하여 Ag 나노 잉크를 PDMS 처리된 PI(Polyimide) 기판 위에 토출하였다. 구동주파수 5 KHz에서 액적부피 1.5 pl, 속도가 약 4.5 m/s인 액적이 토출 되었다. 인쇄된 액적의 크기는 직경 약 $12\;{\mu}m$이었다. 메니스커스의 거동에 맞춘 구동파형의 입력에 의해 새틀라이트 없는 매우 작은 액적을 토출할 수 있었다.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2372-2373
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• 2005

The design of a piezoelectric actuator for micro droplet ejecting system has bee studied. The actuator has been evaluated by using commercial FEM package and its displacement are measured by LDV(Laser Doppler Vibrometer). The characteristics of the actuator are evaluated with varation in a ratio of width of PZT to that of membrane and thickness ratio of PZT to membrane.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1623-1624
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• 2006

It is a paper for design, manufacture and estimation of industry inkjet head. Simulations for Actuator, Ink flow and Ejection are executed for securing design ability. Relations between droplet and properties of ink are explained closely through simulation for nozzle. Actually, two silicon plates are made by dry and wet etching and directly bonded. PZT materials is attached on the bended ink flow part and cut to $540{\mu}m$ interval by dicing saw. Actuator was seen variation within 10% between simulation and actual head. Through the ejection estimation, it is shown that stabilized driving voltages change according to viscosity and surface tension of metal ink. Using the metal ink of viscosity of 4.8 cps and surface tension of 0.025 N/m, it is possible to eject the stable droplets with 5m/s, 20 pl, 5 kHz.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.340-341
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• 2005

Three different composition 130um thickness PZT were fabricated by extrusion method and burned out at $550^{\circ}C$ and sintered at $1260^{\circ}C$/2.5hrs. Actuator was fabricated using glass and Si(100) wafer by MEMS process. From XRD data, in case of DECH, perovskite phase peak strength is higher than others. We were able to obtain the information of grain growth and porosity by SEM images. Also DECH PZT on glass membrane(100um thickness) have larger displacement than others.

• Korean Journal of Optics and Photonics
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• v.17 no.4
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• pp.371-380
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• 2006

We design and fabricate a novel tunable wavelength filter, which utilizes long-range surface plasmon-polaritons excited along nm-thick-metal strips. A gold metal strip, with $\sim$ cm length, 20 nm thickness, and $\sim$ 5$\mu$m width, is embedded in thick thermo-optic Polymer films supported by a silicon wafer. A dielectric Bragg grating structure is Placed on the metal strip, so that transmission signals at telecom wavelength are selected by thermal effect of the thermo-optic polymer. High extinction ratio of 25 dB and total insertion loss of $\sim$25 dB/cm can be measured by single-mode coupling of optical fibers. We also verify that wavelength tuning of the long-range surface plasmon-polariton filters can be achieved by electric current directly applied to the metal-strip waveguides.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1542-1543
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• 2007

This paper presents the effect of driving waveform for piezoelectric bend mode inkjet printhead with optimized mechanical design. Experimental and theoretical studies on the applied driving waveform versus jetting characteristics were performed. The inkjet head has been designed to maximize the droplet velocity, minimize voltage response of the actuator and optimize the firing frequency to eject ink droplet. The head design was carried out by using mechanical simulation. The printhead has been fabricated with Si(100) and SOI wafers by MEMS process and silicon direct bonding method. To investigate how performance of the piezoelectric ceramic actuator influences on droplet diameter and droplet velocity, the method of stroboscopy was used. Using the water based ink of viscosity of 11.8 cps and surface tension of 0.025N/m, it is possible to eject stable droplets through 64 nozzles average velocity of 4.05 m/s with standard deviation of 0.06 m/s and average diameter of $29.2\;{\mu}m$ with standard variation of $0.5\;{\mu}m$.

• Journal of the Korean Ceramic Society
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• v.46 no.2
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• pp.137-145
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• 2009

A remarkable improvement of the productivity in barium titanate by slurry spray pyrolysis process was realized by supplying solid source slurry into the rector. The produced barium titanate powders showed uniform powder properties, and reproducibility with higher tetragonality in the range of 80$\sim$200 nm, case by case. The secondary calcination experiments of the as-prepared powders by spray pyrolysis revealed that the powders as-prepared over 700$^{\circ}C$ showed perfectly different behavior with the lower temperature's ones and the solid state reaction’s case. The result was discussed in terms of the reaction mechanism based on the activation energy analysis.