• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.53-56
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• 2003

A linear power amplifier is particularly emphasized on the CDMA system using a linear modulation scheme, because IMD which cause adjacent channel interference and co channel Interference is mostly generated in a nonlinear power amplifier. In this paper, a new type of linearization technique proposed. It is presented that balanced MESFET predistortion linearizer added. Experimental result are present for Korea PCS frequency band. The implemented linearizer is applied to a 30dBm class. A power amplifier for simulation performance. Two-tone signals at 1850 MHz and 1851.23 MHz are injected into the main power amplifier. The main power amplifier with a 12.1dB gain and a P1dB of 30 dBm(two-tone) was utlized. The reduction of IMD is around 22dB.

• Communications of the Korean Mathematical Society
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• v.35 no.2
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• pp.499-516
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• 2020

In this paper, we denote by L the block matrix linear relation, acting on the Banach space X ⊕ Y, of the form ${\mathcal{L}}=\(\array{A&B\\C&D}\)$, where A, B, C and D are four linear relations with dense domains. We first try to determine the conditions under which a block matrix linear relation becomes a demicompact block matrix linear relation (see Theorems 4.1 and 4.2). Second we study Shechter spectra using demicompact linear relations and relatively demicompact linear relations (see Theorem 5.1).

• ETRI Journal
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• v.33 no.3
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• pp.462-465
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• 2011

A millimeter-wave (mm-wave) high-linear low-noise amplifier (LNA) is presented using a 0.18 ${\mu}m$ standard CMOS process. To improve the linearity of mm-wave LNAs, we adopted the multiple-gate transistor (MGTR) topology used in the low frequency range. By using an MGTR having a different gate-source bias at the last stage of LNAs, third-order input intercept point (IIP3) and 1-dB gain compression point ($P_{1dB}$) increase by 4.85 dBm and 4 dBm, respectively, without noise figure (NF) degradation. At 33 GHz, the proposed LNAs represent 9.5 dB gain, 7.13 dB NF, and 6.25 dBm IIP3.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.10
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• pp.59-64
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• 2008

In this paper an adjustable linear gain equalizer which is operated from 6GHz to 18GHz in order to apply wideband RF circuit System is proposed and fabricated on $Al_2O_3$ substrate using thin film process. An adjustable linear gain equalizer is proposed to T type circuit and designed to aim on variable slope $-7dB{\sim}-13dB$ using the PIN Diode

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.2 s.117
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• pp.105-110
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• 2007

In this paper, a microstripline-type linear amplitude equalizer is implemented to achieve the linearity of the slope of the amplitude over $6{\sim}18$ GHz with resistors inserted between their immediate pairs of a TX-line and a stub. The values of resistors and stubs are explored to have the optimal linear slope and return loss performance. Experiments reveal the slope of around 9 dB variation and return loss of less than 10 dB desired over $6{\sim}18$ GHz and validate the design methodology.

• Journal of Navigation and Port Research
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• v.26 no.3
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• pp.295-302
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• 2002

Currently digital communication system adapt various digital modulation schemes. All these communication systems are required to cause the minimum interference to adjacent channels, they must therefore employ the linear power amplifiers. In respect to linear power amplifiers, there are many linearization techniques. Feedforward power amplifier represent very wide bandwidth and high linearization capability. In the feedforward systems overall efficiency is reduced due to the loss of delay line. In this paper, delay filter instead of transmission delay line adapted to get more high efficiency. Experimental results showed that ACLR has improved 17.04dB which is added 2.54dB by using the delay filter.

• Proceedings of the IEEK Conference
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• summer
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• pp.221-224
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• 2004

This paper proposed an ultra low-power CMOS exponential voltage-mode circuit using the Pseudo-exponential function for realizing the exponential characteristics. The proposed circuit provides high dB-linear output voltage range at low-voltage applications. In a $0.25\;\mu m$ CMOS process, the simulations show more than 35 dB output voltage range and 26 dB with the linearity error less than $\pm0.5\;dB.$ The average current consumption is less than 80 uA. The proposed circuit can be used for the design of an extremely low-power variable gain amplifier (VGA) and automatic gain control (AGC).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.7
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• pp.1383-1388
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• 2016

Although image signal processing is used in many fields, degradation takes place in the process of transmitting image data by several causes. CWMF, A-TMF, and AWMF are the typical methods to eliminate noises from image data damaged under salt and pepper noise environment. However, those filters are not effective for noise rejection under highly dense noise environment. In this respect, the present study proposed an algorithm to remove in salt and pepper noise. In case the center pixel is determined to be non-noise, it is replaced with original pixel. In case the center pixel is noise, it segments local mask into 4 directions and uses linear interpolation to estimate original pixel. And then it applies spatial weight to the estimated pixel. The proposed algorithm shows a high PSNR of 24.56[dB] for House images that had been damaged of salt and pepper noise(P = 50%), compared to the existing CWMF, A-TMF and AWMF there were improvements by 16.46[dB], 12.28[dB], and 12.32[dB], respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.10
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• pp.613-615
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• 2014

The design and implementation of a broadband and linear HPA(High Power Amplifier) for TVWS are presented in this paper. The spectrum mask and transmitted power of HPA for TVWS must be controlled and meet the regulations to minimize interference effects on present broadcasting systems. The implemented HPA has the operating frequency of 460 ~ 698MHz with $24.7{\pm}1dB$ gain, input reflection coefficient of below -25dB, output reflection coefficient of below -7.28dB and the linearity of -57.7dBc at 22.2dBm output power.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.1
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• pp.13-22
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• 2022

In this paper, we propose single and array antenna with dual linear polarization characteristics for 28 GHz band. The proposed antenna is designed two microstirp feeding structure and Taconic TLY-5 substrate, which is thickness 0.5 mm, and the dielectric constant is 2.2. The size of single patch antenna is 3.4 mm×3.4 mm, and total size of single antenna is 15.11 mm×15.11 mm. Also, the size of array antenna is 3.15 mm×3.15 mm, and total size of array antenna is 21.5 mm×13.97 mm. From the fabrication and measurement results, for 1×2 array antenna, in case of vertical polarization, cross polarization ratios are obtained from 14.23 dB to 20.79 dB and in case of horizontal polarization, cross polarization ratios are obtained from 14.31 dB to 22.74 dB for input port 1. in case of vertical polarization, cross polarization ratios are obtained from 15.75 dB to 25.88 dB and in case of horizontal polarization, cross polarization ratios are obtained from 14.70 dB to 22.82 dB for input port 2.