• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.4
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• pp.357-364
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• 2015

In this paper, we designed and implemented a PIFA(Planar Inverted F Antenna) + IFA(Inverted F Antenna) hybrid MIMO(Multi Input Multi Output) antenna for the hexa mobile communication service band. By the simultaneous operation both PIFA and IFA using the coupled feeding structure, we tried for application to modern mobile phones that have large ground size. A PIFA is applied to the ground area, and an IFA is applied to no ground small space on top of the phone. A diagonal fed MIMO antenna is implemented PCB embedded type without antenna carrier component. Implemented antenna on the bare board measured within 3 : 1 for VSWR under hexa mobile communication band as CDMA, GSM900, DCS, KPCS, USPCS, and WCDMA. Measured average gains and efficiencies were -5.19~-3.16 dBi and 30.27~48.26 % for the CDMA, GSM900 band, and -9.50~-5.19 dBi and 11.23~30.28 % for the DCS, KPCS, USPCS, WCDMA band. It's shown that studied antenna can be applied to the antenna for the modern mobile phone.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.2
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• pp.214-219
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• 2011

This paper presents a multi-band low noise amplifier(LNA) with switching operation for 2.4, 3.5 and 5.2 GHz bands using CMOS 0.18 um technology. The proposed circuit uses switching transistors to achieve the input and output matching for multi-band. By using the switching transistors, we can adjust the transconductance, gate inductance and gatesource capacitance at input stage and total output capacitance at output stage. The proposed LNA exhibits gain of 14.2, 12 and 11 dB and noise figure(NF) of 3, 2.9 and 2.8 dB for 2.4, 3.5 and 5.2 GHz, respectively.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.6
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• pp.1222-1236
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• 2010

In this paper, we propose an improved distributed multi-view video coding method that is robust to illumination changes among different views. The use of view dependency is not effective for multi-view video because each view has different intrinsic and extrinsic camera parameters. In this paper, a modified distributed multi-view coding method is presented that applies illumination compensation when generating side information. The proposed encoder codes DC values of discrete cosine transform (DCT) coefficients separately by entropy coding. The proposed decoder can generate more accurate side information by using the transmitted DC coefficients to compensate for illumination changes. Furthermore, AC coefficients are coded with conventional entropy or channel coders depending on the frequency band. We found that the proposed algorithm is about 0.1~0.5 dB better than conventional algorithms.

• Journal of Sensor Science and Technology
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• v.9 no.4
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• pp.307-315
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• 2000

To set up the arrays system of FBG(Fiber Bragg Grating) Hydrophone sensor and realize the multi-point signal detection for the wide scope underwater, using WDM(Wavelength Division Multiplexing) method and Passive band-pass filter system, underwater acoustic signal detection of the newly designed two FBG Transducers is successfully experimented. As a result of the experiment, it was possible each signal with different frequent signals is detected for the multi-point up to 1.3KHz in underwater. We can, therefore, prove the possibility on the system design of Hydrophone sensor arrays, using the newly made FBG Transducers.

• ETRI Journal
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• v.30 no.5
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• pp.735-737
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• 2008

We propose a novel spatial multi-band-stop filter using modified multiple loop array elements to block electromagnetic waves or signals of mobile phones in public facilities. It operates at the following frequency bands: Korean cellular (824 MHz to 894 MHz), Personal Communication Service (PCS) (1.75 GHz to 1.87 GHz), and IMT-2000 (1.92 GHz to 2.17 GHz). Two frequency selective surfaces with modified multiple-loop elements are printed on the top and bottom of a pair-glass pane, which is a pair of glass panes with an air gap between them. A modified multiple-loop element with a meander line is used to make the size of the filter compact. The simulated and measured results show good agreement, which confirms the usefulness of the proposed tri-band spatial filter.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3A
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• pp.232-239
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• 2006

In this paper, we analyze the preamble model for Wireless PAN(WPAN) in proposed Ultra WideBand(UWB) Multi-Band OFDM(MB-OFDM) system of IEEE 802.15.3a standard. Besides, we propose effective Carrier Frequency Offset and Symbol Timing Offset Estimation algorithm which offers enhanced performance, and analyze its performance using Detection Probability, False Alarm Probability, Missing Probability, Mean Acquisition Time and MSE(Mean Square Error) through simulation in AWGN and UWB channel environments.

• International Journal of Advanced Culture Technology
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• v.10 no.4
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• pp.555-560
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• 2022

In this study, the insertion loss and phase delay according to the multi-layer structure radome parameters were analyzed using the boundary value solution approach, and the multi-layer structure and hexa mesh structures with low-loss electrical characteristics for the Ku-band transmission/reception frequency of 10.7 ~ 14.5 GHz were designed and manufactured. A hexa mesh was applied to minimize radio wave transmission and scattering, which lowered the transmittance refractive index according to the radio incident angle and minimized dielectric loss through high-density foam. Similar to the simulation result, the transmission loss obtained the gain in a specific receiving frequency band, and in the transmission frequency band, an excellent low loss characteristic was obtained with an insertion loss of 0.8dB or less. The results of this study can be used in radio transmission radomes of low-weight, low-cost end-system protection devices.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.11
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• pp.1072-1081
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• 2012

For Ka-band satellite communication system, a new flexible payload technologies which can compensate rain attenuation have to be developed. The Ka-band satellite output power control technology enables to adjust downlink output power of satellite payload in Ka-band (19.8 ~ 22.2 GHz). In this paper, we introduce multi-beam antenna with multi-port amplifiers for Ka-band flexible output power allocation system. We have designed multi-beam antenna with array-fed reflector to form 8 beams on the Korean Peninsula. The target EIRP per beam is more than 59 dBW. The system is designed to present 6 dB boost beams for rainfall areas. Individual beams were optimized by the excited amplitude and phase of feed elements of the feed cluster. The multi-port amplifier(MPA) is one of effective approaches for flexible power allocation in combination with multi-beam antenna. In case of using MPA in multi-beam system, the inter-port isolation characteristic of MPA is important parameter to avoid interference among the output ports. In this paper, we propose a new MPA structure that consists of two $4{\times}4$ Buttler matrixes and phase/amplitude controllable power amplifier modules.

• ETRI Journal
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• v.39 no.3
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• pp.398-405
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• 2017

In this paper, an artificial stereo extension method that creates stereophonic sound from a mono sound source is proposed. The proposed method first trains deep neural networks (DNNs) that model the nonlinear relationship between the dominant and residual signals of the stereo channel. In the training stage, the band-wise log spectral magnitude and unwrapped phase of both the dominant and residual signals are utilized to model the nonlinearities of each sub-band through deep architecture. From that point, stereo extension is conducted by estimating the residual signal that corresponds to the input mono channel signal with the trained DNN model in a sub-band domain. The performance of the proposed method was evaluated using a log spectral distortion (LSD) measure and multiple stimuli with a hidden reference and anchor (MUSHRA) test. The results showed that the proposed method provided a lower LSD and higher MUSHRA score than conventional methods that use hidden Markov models and DNN with full-band processing.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.1
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• pp.39-44
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• 2008

In this paper, fully embedded 2.4GHz WLAN band pass filter (BPF) was investigated into a multi-layered organic packaging substrate using high Q spiral stacked inductors and high Dk MIM capacitors for low cost RF System on Package (SOP) applications. The proposed 2.4GHz WLAN BPF was designed by modifying chebyshev second order filter circuit topology. It was comprised of two parallel LC resonators for obtaining two transmission zeros. It was designed by using 2D circuit and 3D EM simulators for finding out optimal geometries and verifying their applicability. It exhibited an insertion loss of max -1.7dB and return loss of min -l7dB. The two transmission zeros were observed at 1.85 and 6.7GHz, respectively. In the low frequency band of $1.8GHz{\sim}1.9GHz$, the stop band suppression of min -23dB was achieved. In the high frequency band of $4.1GHz{\sim}5.4GHz$, the stop band suppression of min -l8dB was obtained. It was the first embedded and the smallest one of the filters formed into the organic packaging substrate. It has a size of $2.2{\times}1.8{\times}0.77mm^3$.