• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.997-1002
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• 2009

This Letter presents a wideband ENG(Epsilon Negative) ZOR(Zeroth-Order Resonant) antenna designed on a microstrip line. It has a mushroom structure and its size is only $7.65{\times}1.31{\times}2.37\;mm$(or $0.306{\times}0.053{\times}0.095\;{\lambda}_0$ at 12 GHz) owing to zeroth-order resonance. The design procedures with closed form solutions are provided using transmission line theory considering radiation loss. The measured antenna bandwidth is about 20.0 % at 9.2 GHz and antenna gain is 7.1 dBi despite the compact size.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.226-226
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• 2012

The electronic and electrical properties of nickel oxide (NiO) thin films were investigated by reflection electron energy loss spectroscopy (REELS), x-ray photoelectron spectroscopy (XPS), and Hall Effect measurements. REELS spectra revealed that the band gap of the NiO thin film was increased from 3.50 eV to 4.02 eV after annealing the sample at $800^{\circ}C$. Our XPS spectra showed that the amount of Ni2O3 decreased after annealing. The Hall Effect results showed that the doping type of the sample changed from n type to p type after annealing. The resistivity decreased drastically from $4.6{\times}10^3$ to $3.5{\times}10^{-2}$ ${\Omega}{\cdot}cm$. The mobility of NiO thin films was changed form $3.29{\times}10^3$ to $3.09{\times}10^5cm^2/V{\cdot}s$. Our results showed that the annealing temperature plays a crucial role in increasing the carrier concentration and the mobility which leads to lowering resistivity of NiO thin films.

• Proceedings of the IEEK Conference
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• summer
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• pp.82-85
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• 2004

This paper proposes an advanced circuit for the capacitive type fingerprint sensor signal processing and an effective isolation structure for minimizing an electrostatic discharge(ESD) influence and for removing a signal coupling noise of each sensor pixel. The proposed detection circuit increases the voltage difference between a ridge and valley about $80\%$ more than old circuit. The test chip is composed of $160\;\times\;192$ array sensing cells $(9,913\times11,666\;um^2).$ The sensor plate area is $58\;\times\;58\;um^2$ and the pitch is 60um. The image resolution is 423 dpi. The chip was fabricated on a 0.35um standard CMOS process. It successfully captured a high-quality fingerprint image and performed the registration and identification processing. The sensing and authentication time is 1 sec(.) with the average power consumption of 10 mW at 3.0V. The reveal ESD tolerance is obtained at the value of 4.5 kV.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.10 s.113
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• pp.1007-1019
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• 2006

In this paper, the synthesis method of multibeam radiation pattern with multi-directional beams and nulls is proposed. Genetic algorithm is applied for the optimization of amplitude and phase of the feeding signal into each element that is structured in planar array of single patch antenna with an arbitrary field distribution. To verify the validity of the proposed method, $2{\times}2$ planar array antenna is used for the measurement and the measured far field radiation pattern is compared with the simulation result. As a result, the synthesis of multibeam radiation pattern is implemented by the optimization of amplitude and phase of the feeding signal into each element of $8{\times}8$ planar array antenna system.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.2
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• pp.305-311
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• 2003

This Paper Presents an information about the heat transfer characteristics of a separate type thermosyphon in electronic equipments. The heat removal problem of electronic equipments is regarded as an important factor and a separate type heatpipes can be utilized as a cooling device of electronic equipments (such as CPU of a Personal computer or notebook). In this study. heat source ($50\times50\times2 mm $aluminum Pseudo CPU) was used for the experiment. The device can transfer heat from the evaporator to the condenser through natural circulation (without any external driving forces) and the results indicate that the device is capable of dissipating over 60W of thermal energy and keeping the heating plate surface temperature under $50^{\circ}C$.

• Journal of Sensor Science and Technology
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• v.5 no.4
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• pp.1-7
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• 1996

Optical intensity-type pressure sensor was fabricated by coupling optical fiber with a micromachined thin dielectric diaphragm, which consists of a 300 nm thick $SiO_{2}$ layer sandwiched between 150 nm thick top and bottom $Si_{3}N_{4}$ layers. At the wavelength of the sensor light source near $1.3\;{\mu}m$, the optical transmittance of the diaphragm was about 50 %, but it was decreased to a few percents by depositing $1,000\;{\AA}$ thick gold(Au) layer on the diaphragm, which is sufficient enough to be used as a light reflection layer of the sensor. From the optical output power-pressure characteristics of the sensors, it was found that the output power linearly decreased with increasing applied pressure from 0 to 77 torr regardless of the diaphragm size. The respective sensitivities were 0.52, 0.65, and 0.77 nW/torr for the diaphragm sizes of $3{\times}3$, $4{\times}4$, and $5{\times}5\;mm^{2}$, indicating that the sensitivity increases as diaphragm size decreases.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.197-200
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• 2004

In this paper, a novel triple-band planar inverted F antenna(PIFA) is proposed. The goal of this paper is to design a small antenna which is operated in triple band. Using T-shape slit and stacked U-shape parasitic patch, good impedance matching is achieved in three band. T-shape slit is inserted on the main patch in order to effectively control the excited patch surface current distributions. The proposed antenna occupies a small volume of $26{\times}9.5{\times}6mm^3$, and the obtained impedance bandwidths cover the required operating bandwidths of the GPS(1565-1585MHz), IMT-2000(1885-2200MHz) and Bluetooth (2400-2484MHz) bands.

• Journal of Sensor Science and Technology
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• v.11 no.4
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• pp.247-253
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• 2002

For fabrication of the pyroelectric IR sensor $(Pb,La)TiO_3(PLT)$/$LiTaO_3$/(LTO)/PLT ferroelectric thin films was deposited by rf magnetron sputtering followed by rapid thermal annealing and the crystallinity as a function of annealing temperature and time was investigated. Permittivity and dielectric loss factor of ferroelectric thin films as a function of c-axis preffered orientation was measured. Also pyroelectric coefficient of ferroelectric thin films with largest c-axis preffered orientation was measured and obtain figure of merit of voltage response($F_V$) and detectivity($F_D$). In this case $F_V$, $F_D$ was $5.63{\times}10^{-10}\;C{\cdot}cm/J$, $1.98{\times}10^{-8}\;C{\cdot}cm/J$, respectively.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1488-1490
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• 1997

$(Pb_{1-x}La_x)Ti_{1-x/4}O_3$ (x=0, 0.02, 0.04, 0.06, 0.08) ceramic thin films were fabricated by Sol-Gel method. A stock solution of (Pb,La)$TiO_3$ with excess Pb 10mol% was made and spin-coated on the Pt/Ti/$SiO_2$/Si substrate at 4000rpm for 30 seconds. Coated specimens were dried on the hot-plate at $350^{\circ}C$ for 10 min and sintered at $500{\sim}750^{\circ}C$ for 1 hour. The dielectric constant, remanent polarization and coercive field of the PLT(6 at.%) thin films sintered at $650^{\circ}C$ were 884, $13.95{\mu}C/cm^2$ and 8.7kV/cm, respectively. Pyroelectric coefficient, figure of merit of pyroelectric current, voltage responsivity and detectivity of PLT(6at.%) thin films were $3.2{\times}10^{-8}\;C/cm^2K$, $1.02{\times}10^{-8}\;C{\cdot}cm/J$, $2.9{\times}10^{-11}\;C{\cdot}cm/J$, $0.29{\times}10^{-8}\;C{\cdot}cm/J$, respectively.

• Journal of Broadcast Engineering
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• v.13 no.3
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• pp.310-318
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• 2008

The H.264/AVC standard achieves higher coding efficiency than previous video coding standards with the rate-distortion optimization (RDO) technique which selects the best coding mode and reference frame for each macroblock. As a result, the complexity of the encoder have been significantly increased. In this paper, a fast intra-mode decision algorithm is proposed to reduce the computational load of intra-mode search, which is based on the inverse tree-structure edge prediction algorithm. First, we obtained the dominant edge for each $4{\times}4$ block from local edge information, then the RDO process is only performed by the mode which corresponds to dominant edge direction. Then, for the $8{\times}8$ (or $16{\times}16$) block stage, the dominant edge is calculated from its four $4{\times}4$ (or $16{\times}16$) blocks' dominant edges without additional calculation and the RDO process is also performed by the mode which is related to dominant edge direction. Experimental results show that proposed scheme can significantly improve the speed of the intra prediction with a negligible loss in the peak signal to noise ratio (PSNR) and a little increase of bits.