• Bulletin of the Korean Mathematical Society
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• v.53 no.6
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• pp.1823-1830
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• 2016

Let H and K be two Hilbert spaces, and let A and B be two bounded linear operators from H to K. We are interested in $RangeB^*{\supseteq}RangeA^*$. It is well known that this is equivalent to the inequality $A^*A{\geq}{\varepsilon}B^*B$ for a positive constant ${\varepsilon}$. We study conditions in terms of symbols when A and B are singular integral operators, Hankel operators or Toeplitz operators, etc.

• Bulletin of the Korean Mathematical Society
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• v.55 no.4
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• pp.1137-1147
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• 2018

In this paper, we discovered a sufficient condition ensuring the weighted composition operators $C_{{\omega}_1,{\varphi}_1},{\cdots},C_{{\omega}_N,{\varphi}_N}$ were disjoint supercyclic on $H({\Omega})$ endowed with the compact open topology. Besides, we provided a condition on inducing symbols to guarantee the disjoint supercyclicity of non-constant adjoint multipliers $M^*_{{\varphi}_1},M^*_{{\varphi}_2},{\cdots},M^*_{{\varphi}_N}$ on a Hilbert space ${\mathcal{H}}$.

• Bulletin of the Korean Mathematical Society
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• v.53 no.3
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• pp.711-722
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• 2016

We study Toeplitz operators $T_{\nu}$ on generalized Fock spaces $F^2_{\phi}$ with a locally finite positive Borel measures ${\nu}$ as symbols. We characterize operator-theoretic properties (boundedness and compactness) of $T_{\nu}$ in terms of the Fock-Carleson measure and the Berezin transform ${\tilde{\nu}}$.

• Bulletin of the Korean Mathematical Society
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• v.47 no.4
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• pp.839-857
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• 2010

We give a set of continuous characterizations for the homogeneous Triebel-Lizorkin spaces and use them to study boundedness properties of Fourier multiplier operators whose symbols satisfy a generalization of H$\ddot{o}$rmander's condition. As an application, we give new direct proofs of the imbedding theorems of the Sobolev type.

• Journal of information and communication convergence engineering
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• v.9 no.2
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• pp.183-186
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• 2011

In this work, we consider imperfectness of feedback channels in the adaptive transmission scheme which was previously studied with an assumption of error-free feedback channels. New method of mapping the modulation index into the feedback channel symbols and quantifying feedback error over fading channels are proposed. The presented method and results are expected to offer valuable tools for the system designer to efficiently implement adaptive diversity schemes to compensate for the performance degradation due to feedback error.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.199-200
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• 2008

In this paper, efficient time synchronization scheme for OFDM based WLAN system and its performance simulation results are presented. Assuming AGC and packet detection is done within 7 short training symbols. This scheme consists of coarse and fine estimation, and exhibits robustness over fading and AWGN channel. The presented synchronization scheme achieves the success rate of about 96% over the SNR of 5 dB.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.1102-1107
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• 1992

Existing CAD systems do nto provide the advanced function for systematic checking of design and drafting errors in mechanical drawings. This paper describes a method for sytematic checking of global parts in mechanical drawings. The checking items are deficiency and redundancy of dimensions, input-errors in dimension figures and symbols, etc. Checking for deficiency and redundancy of global dimensions has been performed applying Graph Theory. This system has been applied to several examples and we have confirmed the feasibility of this checing method.

• Journal of Institute of Control, Robotics and Systems
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• v.2 no.3
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• pp.229-235
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• 1996

CAD diagrams generally consists of many basic components: symbols, character, and connection lines. Thus, to recognize the diagrams, it is necessary to extract each components, and understand their meanings and relation among them. This paper describes a method for linking basic components extracted efficiently from hand-down diagrams to OrCAD data format. Experimental results with a hand-drawn diagrams of electronic and logic circuit show utility of the proposed method.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.938-941
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• 1999

In this paper, we designed a pipeline (15,9) Reed-solomon decoder. To compute the error locator polynomials, we used the Euclidean algorithm. This algorithm includes computation of inverse element. We avoided the inverse element calculation in this RS decoder by using ROMs. We designed this decoder using VHDL. Simulation results show that the designed decoder corrects three error symbols. We implemented this design through an Altera FPGA chip.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.81-85
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• 1999

DWMT VDSL system needs A/D converter clock, bit clock, symbol clock, frame clock, etc. DMT ADSL system utilizes a correlation method which makes use of cyclic prefix or preamble pattern for clock recovery. But the correlation method is difficult to apply to the DWMT system because modulated symbols are overlapped in the time domain. This paper proposes a novel clock recovery method which can be used for the DWMT system due to its inherent independence of the modulation method. This new method is verified by SPICE simulations.