• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.12
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• pp.1176-1179
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• 2011

In this paper, design of series-fed microstrip antennas with sum and difference patterns is presented for millimeter-wave applications. The antenna was designed to exhibit high-gain and low side-lobe level(SLL) below -20 dB. A conventional transmission-line model, Taylor and Bayliss distributions were employed to determine current distribution for sum and difference patterns. Moreover, connecting lines between microstrip patches were tuned to achieve an optimized design. The measurement was also performed to validate the designed antennas.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.4 no.2
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• pp.34-40
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• 1993

A microstrip antenna for mobile system are designed at the resont frequency 0.88 GHz. The microstrip array antenna are designed to depend on the size of rectanular microstrip path for the relative current distribution to be 1:4.69:1 using Tchebyscheff polynominals. Gain difference between the main lobe and sidelobe is calculated for theoritical values of 20 dB. The designed microstrip array antenna are mesureed various characteristics, such as return loss, radiation pattern, V.S.W.R, bandwidth, and agreed with each other and theoretical value. Also it is presented a process of phase variation of patch array antenna depend on relative current distribution for beam scanning.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1194-1197
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• 2005

Micro nozzle is employed as a dynamic passive valve in micro fluidic devices. Micro nozzle array is used in micro droplet generation in bio-medical applications and propulsion device for actuating satellite and aerospace ship in vacuum environments. Aperture angle and the channel length of the micro nozzle affect its retification efficiency, and thus it is needed to produce micro nozzle precisely. MEMS process has a limit on making a micro nozzle with high-aspect ratio. Reactive ion etching process can make high-aspect ratio structure, but it is difficult to make the complex shape. Focused ion beam deposition has advantage in machining of three-dimensional complex structures of sub-micron size. Moreover, it is possible to monitor machining process and to correct defected part at simultaneously. In this study, focused ion beam deposition was applied to micro nozzle production.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1116-1120
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• 2010

Low cost patch array antenna for high sensitivity electromagnetic(EM) sensor is presented. The operating frequency band of the antenna is 24.05~24.25 GHz. Array structure is the symmetrical pattern by Chebyshev polynomial and the feed point is located in the middle of the array. Also, the gain of the array antenna can be increased by the side wings which are connected with the ground plane. It is proved through simulation and the measurement results that the operating frequency and the side-lobe level(SLL) are rarely changed when the inclined angle of the side wings is varied.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.8
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• pp.966-974
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• 2011

The use of ion beams in the micro/nano scale is greatly increased by technology development. Especially, focused ion beams (FIBs) have a great potential to fabricate the device in sub micro scale. Nevertheless, FIB has several limitations, surface swelling in low ion dose regime, precipitation of incident ions, and the redeposition effect due to the sputtered atoms. In this research, we demonstrate a way which can be used to fabricate mold structures on a silicon substrate using FIBs. For the purpose of the demonstration, two essential subjects are necessary. One is that focused ion beam diameter as well as shape has to be measured and verified. The other one is that the accurate rotational symmetric model of ion-solid interaction has to be mathematically developed. We apply those two, measured beam diameter and mathematical model, to fabricate optical lenses mold on silicon. The characteristics of silicon mold fabrication will be discussed as well as simulation results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.5
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• pp.795-801
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• 2001

A method of miniaturizing branch line coupler is presented. The method utilizes the microstrip line with overlay(or superstrate). The frequency dependent characteristics, dispersion and characteristic impedance, of this line are obtained by Immitance method in spectral domain and Method of Line. The relevant spectral domain Green's function is given and used to obtain numerical results. The branch line couplers with overlays are designed and fabricated at 2 GHz. The experimental results show that the size of coupler with overlay(${epsilon}_r$=10.2) is 31.4 precent smaller than conventional coupler. This minimized coupler is suitable for Butler Matrix as feeder for mobile communication beam forming antenna.

• Journal of Sensor Science and Technology
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• v.6 no.6
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• pp.430-436
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• 1997

A piezoresistive acceleration sensor for 30 G has been fabricated by silicon micromachining method using SDB(silicon direct bonding) wafer. The structure of the piezoresistive acceleration sensor consists of a seismic square pillar type mass and four beams. This structure was fabricated by reactive ion etching and chemical etching using KOH-etchant. The rectangular square structure is used in order to compensate the deformation of the edges due to underetching. The fabricated sensor showed a linear output voltage-acceleration characteristics and its sensitivity was about $88{\mu}V/V{\cdot}g$ from 0 to 10 G.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.6
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• pp.574-581
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• 2002

Microstrip $8{ imes}2$ sub-array antennas for a extension to active phased array antennas are designed, fabricated and measured for TX/RX dual operation in satellite communication and a reception of satellite broadcasting. For the frequency range from 11.7 to 12.75 GHz for RX and from 14 to 14.5 GHz for TX, two orthogonal linear polarizations of ${pm}45^{\circ}$ are used to transmit and receive simultaneously with one radiator. They adopt dual resonance between two patches for wideband characteristics in RX band and show isolation characteristics over 20 dB. An electrical beam tilt of $30^{\circ}$ is achieved and a tapered power distribution, narrow element spacing are used for the purpose of low side-lobe characteristics.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.6
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• pp.598-604
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• 2011

A method of miniaturizing branch line coupler with connected coupled lines is presented. The quarter-wavelength transmission lines in the typical microstrip branch line coupler are replaced with the connected coupled lines with same characteristics of ones for compact size. The connected coupled line is analyzed by T-equivalent circuit and Z parameters based on the even-odd mode analysis. The proposed branch line couplers with connected coupled line are designed and fabricated on FR4 substrate at 2.4 GHz. The measured results show good agreement with theoretical prediction. And the experimental results show that the size of coupler is 37 precent smaller than conventional coupler. This minimized coupler is suitable for Butler Matrix as feeder for mobile communication beam forming antenna.

• Journal of the Microelectronics and Packaging Society
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• v.20 no.1
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• pp.7-13
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• 2013

3D stacked IC is one of the promising candidates which can keep Moore's law valid for next decades. IC can be stacked through various bonding technologies and they were reviewed in this report, for example, wafer direct bonding and atomic diffusion bonding, etc. As an effort to reduce the high temperature and pressure which were required for high bonding strength in conventional Cu-Cu thermo-compression bonding, surface activated bonding, solid liquid inter-diffusion and direct bonding interface technologies are actively being developed.